Current issue: 53(3)

Under compilation: 53(4)

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Silva Fennica 1926-1997
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Acta Forestalia Fennica
1953-1968
1933-1952
1913-1932

Articles containing the keyword 'Pinus sylvestris'.

Category: Research article

article id 10179, category Research article
Lauri Korhonen, Jaakko Repola, Tomi Karjalainen, Petteri Packalen, Matti Maltamo. (2019). Transferability and calibration of airborne laser scanning based mixed-effects models to estimate the attributes of sawlog-sized Scots pines. Silva Fennica vol. 53 no. 3 article id 10179. https://doi.org/10.14214/sf.10179
Highlights: Attributes of individual sawlog-sized pines estimated by transferring ALS-based models between sites; Mixed effects models were more accurate than k-NN imputation tested earlier; Calibration with a small number of field measured trees improved the accuracy.

Airborne laser scanning (ALS) data is nowadays often available for forest inventory purposes, but adequate field data for constructing new forest attribute models for each area may be lacking. Thus there is a need to study the transferability of existing ALS-based models among different inventory areas. The objective of our study was to apply ALS-based mixed models to estimate the diameter, height and crown base height of individual sawlog sized Scots pines (Pinus sylvestris L.) at three different inventory sites in eastern Finland. Different ALS sensors and acquisition parameters were used at each site. Multivariate mixed-effects models were fitted at one site and the models were validated at two independent test sites. Validation was carried out by applying the fixed parts of the mixed models as such, and by calibrating them using 1–3 sample trees per plot. The results showed that the relative RMSEs of the predictions were 1.2–6.5 percent points larger at the test sites compared to the training site. Systematic errors of 2.4–6.2 percent points also emerged at the test sites. However, both the RMSEs and the systematic errors decreased with calibration. The results showed that mixed-effects models of individual tree attributes can be successfully transferred and calibrated to other ALS inventory areas in a level of accuracy that appears suitable for practical applications.

  • Korhonen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID: http://orcid.org/0000-0002-9352-0114 E-mail: lauri.korhonen@uef.fi (email)
  • Repola, Natural Resources Institute of Finland (Luke), Natural resources, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: jaakko.repola@luke.fi
  • Karjalainen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: tomikar@uef.fi
  • Packalen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: petteri.packalen@uef.fi
  • Maltamo, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: matti.maltamo@uef.fi
article id 10055, category Research article
Jaakko Repola, Hannu Hökkä, Hannu Salminen. (2018). Models for diameter and height growth of Scots pine, Norway spruce and pubescent birch in drained peatland sites in Finland. Silva Fennica vol. 52 no. 5 article id 10055. https://doi.org/10.14214/sf.10055
Highlights: Tree growth strongly correlated with site drainage status; Between-tree competition had a higher impact on tree diameter growth than on height growth; Growth predicted by the constructed models were calibrated using NFI11 data to ensure generally applicable growth predictions level in whole country.

The aim of this study was to develop individual-tree diameter and height growth models for Scots pine, Norway spruce, and pubescent birch growing in drained peatlands in Finland. Trees growing in peatland sites have growth patterns that deviate from that of trees growing in mineral soil sites. Five-year growth was explained by tree diameter, different tree and stand level competition measures, management operations and site characteristics. The drainage status of the site was influencing growth directly or in interaction with other variables. Site quality had a direct impact but was also commonly related to current site drainage status (need for ditch maintenance). Recent thinning increased growth of all species and former PK fertilization increased growth of pine and birch. Temperature sum was a significant predictor in all models and altitude for spruce and birch. The data were a subsample of the 7th National Forest Inventory (NFI) sample plots representing northern and southern Finland and followed by repeated measurements for 15–20 yrs. Growth levels predicted by the models were calibrated using NFI11 data to remove bias originating from the sample of the modelling data. The mixed linear models technique was used in model estimation. The models will be incorporated into the MOTTI stand simulator to replace the current peatlands growth models.

  • Repola, Natural Resources Institute Finland (Luke), Natural resources, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: jaakko.repola@luke.fi (email)
  • Hökkä, Natural Resources Institute Finland (Luke), Natural resources, Paavo Havaksen tie 3, FI-90014 University OF Oulu, Finland ORCID ID:E-mail: hannu.hokka@luke.fi
  • Salminen, Natural Resources Institute Finland (Luke), Natural resources, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: hannu.salminen@luke.fi
article id 10040, category Research article
Bengt Andersson Gull, Torgny Persson, Aleksey Fedorkov, Tim J. Mullin. (2018). Longitudinal differences in Scots pine shoot elongation. Silva Fennica vol. 52 no. 5 article id 10040. https://doi.org/10.14214/sf.10040
Highlights: More northerly Scots pine origins exhibit earlier onset and cessation of shoot growth; Continental origins show more northern phenological behaviour; Heat accumulation requirements for onset are not fixed and may be lower when accumulating slower; Scots pine may suffer from spring frost due to earlier growth onset in a warming climate; Phenological traits show potential to adapt to new climate conditions by breeding.

Phenology can have a profound effect on growth and climatic adaptability of long-lived, northern tree species such as Scots pine (Pinus sylvestris L.), where the onset of growth in the spring is triggered mainly by accumulated heat, while cessation of growth is related to the joint effect of photoperiod and temperature. In this study, the objectives were: (1) to compare shoot phenology of genetic material from Scandinavia (maritime climate origin) and northern Russia (continental climate origin) sources, under field conditions in both Scandinavia and Russia (maritime and continental growth conditions); and (2) to estimate the heritabilities of phenological parameters. The material used was part of a larger provenance test series involving Scots pine populations and open-pollinated plus-tree families from Russia, Sweden and Finland. Terminal shoot elongation was measured on multiple occasions during the seventh growing season from seed at a trial near Bäcksjön (Sweden) and Syktyvkar (northern Russia). We calculated the regression of relative shoot elongation over accumulated heat sum above +5 °C using an exponential expression. Seedlings of Swedish and Russian provenance had similar heat-sum requirements for growth onset and cessation in both trials. More northern provenances started onset and cessation at a lower temperature sum, but heat accumulation requirements for onset were not fixed. Scots pine may suffer from spring frost due to earlier growth onset in a warming climate. Variation and heritability of phenological traits show potential to adapt Scots pine to new climate conditions by breeding.

  • Andersson Gull, The Swedish Forestry Research Institute (Skogforsk), Box 3, SE-918 21 Sävar, Sweden ORCID ID: https://orcid.org/0000-0003-3556-3172 E-mail: bengt.anderssongull@skogforsk.se
  • Persson, The Swedish Forestry Research Institute (Skogforsk), Box 3, SE-918 21 Sävar, Sweden ORCID ID:E-mail: torgny.persson@skogforsk.se
  • Fedorkov, The Institute of Biology of Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences (IB Komi SC UB RAS), Kommunisticheskaya St., 28, Syktyvkar, 167982, Russia ORCID ID: https://orcid.org/0000-0001-7800-7534 E-mail: fedorkov@ib.komisc.ru
  • Mullin, The Swedish Forestry Research Institute (Skogforsk), Box 3, SE-918 21 Sävar, Sweden ORCID ID: https://orcid.org/0000-0003-4924-1836 E-mail: tim.mullin@skogforsk.se (email)
article id 10013, category Research article
Hardo Becker, Jürgen Aosaar, Mats Varik, Gunnar Morozov, Kristiina Aun, Ülo Mander, Kaido Soosaar, Veiko Uri. (2018). Annual net nitrogen mineralization and litter flux in well-drained downy birch, Norway spruce and Scots pine forest ecosystems. Silva Fennica vol. 52 no. 4 article id 10013. https://doi.org/10.14214/sf.10013
Highlights: The net nitrogen mineralization (NNM) flux in drained peat soils depends largely on the C/N ratio and tree species; The soil NNM process is affected by trees through organic litter input into soil; Pine stand in low-fertility drained transitional bog is dominated by net ammonification; Birch and spruce stands on the fertile drained peat soil with higher pH and N content are dominated by net nitrification.

The main aim of the current study was to estimate the annual net nitrogen mineralization (NNM) flux in stands of different tree species growing on drained peatlands, as well as to clarify the effect of tree species, soil properties and litter on annual NNM dynamics. Three study sites were set up in May 2014: a downy birch (Betula pubescens Ehrh.) stand and a Norway spruce (Picea abies (L.) Karst.) stand in Oxalis full-drained swamp (ODS) and a Scots pine (Pinus sylvestris L.) stand in Myrtillus full-drained swamp (MDS). The NNM flux was estimated using the in situ method with incubated polyethylene bags. The highest value of NNM was found in stands that were growing on fertile ODS: 127.5 kg N ha–1 yr–1 and 87.7 kg N ha–1 yr–1, in the downy birch stand and in the Norway spruce stand, respectively. A significantly lower annual NNM flux (11.8 kg N ha–1 yr–1) occurred in the Scots pine stand growing in MDS. Nitrification was highest at fertile ODS sites and ammonification was the highest at the low fertility MDS site. For all study sites, positive correlation was found between soil temperature and NNM intensity. The difference in annual NNM between the downy birch stand and the Norway spruce stand growing on similar drained fertile peatlands was due to litter quality. The annual N input into the soil through leaf litter was the highest at the downy birch site where also the C/N ratio of litter was the lowest. The second highest N input into the soil was found in the spruce stand and the lowest in the pine stand.

  • Becker, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: hardo.becker@emu.ee (email)
  • Aosaar, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: jyrgen.aosaar@emu.ee
  • Varik, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: mats.varik@emu.ee
  • Morozov, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: gunnar.morozov@emu.ee
  • Aun, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: kristiina.aun@emu.ee
  • Mander, Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, Ülikooli 18, 50090 Tartu, Estonia ORCID ID:E-mail: ulo.mander@ut.ee
  • Soosaar, Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, Ülikooli 18, 50090 Tartu, Estonia ORCID ID:E-mail: kaido.soosaar@ut.ee
  • Uri, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: veiko.uri@emu.ee
article id 9946, category Research article
Frauke Fedderwitz, Niklas Björklund, Velemir Ninkovic, Göran Nordlander. (2018). Does the pine weevil (Hylobius abietis) prefer conifer seedlings over other main food sources? Silva Fennica vol. 52 no. 3 article id 9946. https://doi.org/10.14214/sf.9946
Highlights: Adult pine weevils feed on seedlings and mature conifers, but cause economic damage only on seedlings; Their feeding preferences for branches and roots over seedlings were tested in a laboratory experiment; The only clear preference was for Norway spruce roots; Results support new approaches of seedling protection attempting to redirect pine weevils from planted seedlings to other food sources.

Adult pine weevils (Hylobius abietis (L.)) feed on the tender bark of branches and roots of mature conifer trees and on the stem bark of conifer seedlings. Their feeding on mature trees does not cause any economic damage, but their feeding on planted seedlings is so devastating that the pine weevil is considered one of the most important forest pest insects in Europe. We asked whether the pine weevil prefers seedlings over other regularly utilized food sources. This question is of particular interest because new approaches to seedling protection are based on decreasing any preference for seedlings by using less palatable plants or by enhancing their defence (by genetic selection or by methyl jasmonate treatment). In a laboratory choice experiment we tested pine weevil feeding preferences for seedlings compared with branches and roots from mature trees (separately for Norway spruce and Scots pine). Pine weevils preferred roots, but not branches, of Norway spruce over seedlings of the same species. With Scots pine there were no clear preferences, but the weevils showed a tendency to prefer roots over seedlings. These results provide support for seedling protection approaches that attempt to redirect pine feeding from planted seedlings to other food sources.

  • Fedderwitz, Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: frauke.fedderwitz@slu.se (email)
  • Björklund, Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: niklas.bjorklund@slu.se
  • Ninkovic, Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: velemir.ninkovic@slu.se
  • Nordlander, Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: goran.nordlander@slu.se
article id 7738, category Research article
Samuel Egbäck, Bo Karlsson, Karl-Anders Högberg, Kenneth Nyström, Mateusz Liziniewicz, Urban Nilsson. (2018). Effects of phenotypic selection on height-diameter ratio of Norway spruce and Scots pine in Sweden. Silva Fennica vol. 52 no. 2 article id 7738. https://doi.org/10.14214/sf.7738
Highlights: Swedish plus-tree selection promoted less slender Norway spruce trees and more slender Scots pine trees compared to neighboring trees; Similar results were also found for progeny trials which indicated that genetics played a prominent role in phenotypic appearance.

Genetically improved Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) are extensively used in operational Swedish forestry plantations. However, relatively little is known about the stem slenderness (height-diameter ratio) of genetically improved material. Thus, in this study we investigated effects of plus-tree selection on stem slenderness of Norway spruce and Scots pine in Sweden by evaluating both the plus-tree selection and a large number of progeny trials. Species-specific models for predicting the height-diameter ratio were estimated using regression and mixed model approach. Our results show that phenotypic plus-tree selection promoted less slender Norway spruce trees and more slender Scots pine trees compared to neighboring trees. Similar results were also found for the progeny trials which indicated that genetics played a prominent role in the phenotypic appearance. Compared to the progeny of neighboring trees, Norway spruce plus-tree progenies had a 5.3% lower height-diameter ratio, while Scots pine plus-tree progenies had a 1.5% greater height-diameter ratio. The narrow sense heritability for height-diameter ratio was 0.19 for Norway spruce and 0.11 for Scots pine, indicating that it is possible to modify the height-diameter ratio by breeding. Correlation coefficients between breeding values for height-diameter ratio and diameter were negative for Scots pine (–0.71) and Norway spruce (–0.85), indicating that selection for diameter only would result in less slender stems of both species. Similar correlations were also found between breeding values for height-diameter ratio and height of Scots pine (–0.34) and Norway spruce (–0.74).

  • Egbäck, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, 230 53 Alnarp, Sweden ORCID ID:E-mail: samuel.egback@slu.se (email)
  • Karlsson, Skogforsk, Ekebo, 268 90 Svalöv, Sweden ORCID ID:E-mail: bo.karlsson@skogforsk.se
  • Högberg, Skogforsk, Ekebo, 268 90 Svalöv, Sweden ORCID ID:E-mail: karl-anders.hogberg@skogforsk.se
  • Nyström, Swedish University of Agricultural Sciences, Department of Forest Resource Management, Skogsmarksgränd, 901 83 Umeå, Sweden ORCID ID:E-mail: kenneth.nystrom@slu.se
  • Liziniewicz, Skogforsk, Ekebo, 268 90 Svalöv, Sweden ORCID ID:E-mail: Mateusz.Liziniewicz@skogforsk.se
  • Nilsson, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, 230 53 Alnarp, Sweden ORCID ID:E-mail: urban.nilsson@slu.se
article id 7783, category Research article
Markku T. Lehtinen, Pertti Pulkkinen. (2017). Effects of Scots pine paternal genotypes of two contiguous seed orchards on the budset and frost hardening of first-year progeny. Silva Fennica vol. 51 no. 5 article id 7783. https://doi.org/10.14214/sf.7783
Highlights: This environmentally controlled study on Scots pine demonstrated the effect of the paternal genotype on the budset and frost hardening of the progeny; With the applied study design, no significant indication of an environmental influence on the effect of the Scots pine paternal genotype was obtained.

In Scots pine (Pinus sylvestris L.), it has been shown that the parental conditions have a role in the phenological variation among first-year seedlings. For this reason, it is argued that they should be comprehensively controlled before estimating the parental genotype effects. This controlled-cross study examined the effects of a set of fathers of Scots pines on the timing of budset and autumn frost hardening of first-year seedlings. The paternal genotypes had either a northern or southern provenance, but had spent a period of over 25 years as grafts in a shared climatic environment in two closely located southern orchards. Pollen applied in the crosses was collected from these orchards in one year and all the maternal genotypes were pollinated in only one seed orchard. The results of freeze tests and budset observations of the consequent progeny were analysed and additionally compared with results obtained using seedlings from seed lots of natural forests in order to estimate the ability of northern paternal genotypes to maintain a northern effect under southern conditions. This environmentally controlled study demonstrated a significant effect of the paternal genotype on the budset and autumn frost hardening of first-year seedling of Scots pine. With the applied study design, no significant indication of an environmental influence on the effect of the paternal genotype was obtained. The accuracy of the observations is discussed. It is concluded that the results suggest a minor role of mutability in the effects of Scots pine paternal genotypes.

  • Lehtinen, University of Helsinki, Department of Agricultural Sciences, Latokartanonkaari 5 and 7, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: markku.t.lehtinen@helsinki.fi (email)
  • Pulkkinen, Natural Resources Institute Finland (Luke), Green Technology, Haapastensyrjäntie 34, FI-12600 Läyliäinen, Finland ORCID ID:E-mail: pertti.pulkkinen@luke.fi
article id 1760, category Research article
Marek Fajstavr, Kyriaki Giagli, Hanuš Vavrčík, Vladimír Gryc, Josef Urban. (2017). The effect of stem girdling on xylem and phloem formation in Scots pine. Silva Fennica vol. 51 no. 4 article id 1760. https://doi.org/10.14214/sf.1760
Highlights: Stem girdling ceased the cambial activity, below the girdled area, immediately after the removal of the bark strip; Pinus sylvestris survived for up to two years after stem girdling; The girdled trees formed phloem cells above the girdled area but failed to form latewood cells in the next growing season.

Scots pine (Pinus sylvestris L.) is a resilient, wide spread species. This paper reports on the xylem and phloem cell formation process, before and after, the species was put under artificial stress by stem girdling. Microcore method was applied to a healthy control group and a standing group of girdled trees within an 80-year-old pine forest for two consecutive growing seasons (2013 and 2014). The stem girdling was applied in the middle of the first growing season (July 2013). Cambial activity timings (onset and cessation of cell division), cell formation intensity, cell differentiation, and the dynamics of the annual radial increment in the stem were analyzed. Cambial activity was inhibited and eventually ceased below the stem girdling immediately after the removal of the strip. Therefore, no latewood tracheids were formed. However, above the stem girdling and in the control trees, cell formation and tissue differentiation continued until the end of the growing season, with the girdled trees moving at a less intensive pace but for a longer period of time. During the following growing season (2014), the cambial zone was reactivated only above the stem girdling, not below, and eventually the girdled trees died. In 2014, the onset of the cambial activity was delayed and the division rate of the cells was slower in the girdled trees. Furthermore, the girdled trees formed less phloem cells than the control trees.

  • Fajstavr, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: fajstavr.marek@seznam.cz (email)
  • Giagli, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: kyriaki.giagli@mendelu.cz
  • Vavrčík, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: vavrcik@mendelu.cz
  • Gryc, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: gryc@mendelu.cz
  • Urban, Department of Forest Botany, Dendrology and Geobiocenology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic;  Siberian Federal University, Svobodnyj Prospect 79, Krasnoyarsk, 660041 Krasnoyarsk, Russia ORCID ID:E-mail: josef.urban@email.cz
article id 5662, category Research article
Samuel Egbäck, Urban Nilsson, Kenneth Nyström, Karl-Anders Högberg, Nils Fahlvik. (2017). Modeling early height growth in trials of genetically improved Norway spruce and Scots pine in southern Sweden. Silva Fennica vol. 51 no. 3 article id 5662. https://doi.org/10.14214/sf.5662
Highlights: The developed height growth model based on unimproved material predicted the development relatively well for genetically improved Norway spruce; For genetically improved Scots pine, however, the model needed to be modified; By incorporating a genetic component into the Scots pine model, the prediction errors were reduced.

Genetically improved Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) are used extensively in operational Swedish forestry plantations to increase production. Depending on the genetic status of the plant material, the current estimated genetic gain in growth is in the range 10–20% for these species and this is expected to increase further in the near future. However, growth models derived solely from data relating to genetically improved material in Sweden are still lacking. In this study we investigated whether an individual tree growth model based on data from unimproved material could be used to predict the height increment in young trials of genetically improved Norway spruce and Scots pine. Data from 11 genetic experiments with large genetic variation, ranging from offspring of plus-trees selected in the late 1940s to highly improved clonal materials selected from well performing provenances were used. The data set included initial heights at the age of 7–15 years and 5-year increments for almost 2000 genetic entries and more than 20 000 trees. The evaluation indicated that the model based on unimproved trees predicted height development relatively well for genetically improved Norway spruce and there was no need to incorporate a genetic component. However, for Scots pine, the model needed to be modified. A genetic component was developed based on the genetic difference recorded within each trial, using mixed linear models and methods from quantitative genetics. By incorporating the genetic component, the prediction errors were significantly reduced for Scots pine. This study provides the first step to incorporate genetic gains into Swedish growth models and forest management planning systems.

  • Egbäck, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, 230 53 Alnarp, Sweden ORCID ID:E-mail: samuel.egback@slu.se (email)
  • Nilsson, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, 230 53 Alnarp, Sweden ORCID ID:E-mail: urban.nilsson@slu.se
  • Nyström, Swedish University of Agricultural Sciences, Department of Forest Resource Management, Skogsmarksgränd, 901 83 Umeå, Sweden ORCID ID:E-mail: kenneth.nystrom@slu.se
  • Högberg, Skogforsk, Ekebo, 268 90 Svalöv, Sweden ORCID ID:E-mail: karl-anders.hogberg@skogforsk.se
  • Fahlvik, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, 230 53 Alnarp, Sweden ORCID ID:E-mail: nils.fahlvik@slu.se
article id 1734, category Research article
Jyrki Hytönen, Paula Jylhä, Keith Little. (2017). Positive effects of wood ash fertilization and weed control on the growth of Scots pine on former peat-based agricultural land – a 21-year study. Silva Fennica vol. 51 no. 3 article id 1734. https://doi.org/10.14214/sf.1734
Highlights: Weed control decreased and fertilization increased vegetation height and shading of seedlings; Weed control decreased mortality, but fertilization had no effect; Despite improved foliar K concentration though ash fertilization, all trees in the trial had severe K deficiency after 21 years; Weed control increased growth by 20 m3 ha–1 and fertilization by 35 m3 ha–1 in 21 years.

The impacts of weed control, ash fertilization and their interaction were tested for the afforestation of former agricultural peat-based soil with Scots pine (Pinus sylvestris L.) in northern Finland in a factorial arrangement of four treatments. Weed control with herbicides was carried out in July 1 and 2 years from planting, and wood ash (5 Mg ha–1) was applied in the spring of the 2nd year. Various vegetation, tree growth and nutrient assessments were made over the 21-year study period. Weed control decreased the weed cover by 36–56 percentage points, vegetation height by 4–26 cm and thus shading of seedlings by vegetation for at least 4 years after planting. For the same period, ash fertilization increased vegetation height by 6–15 cm and shading of seedlings. Weed control reduced seedling mortality by 27 percentage points in 21 years, but ash fertilization had no significant effect. Ash fertilization increased foliar potassium and boron concentrations, but its effect declined, and severe K-deficiency was recorded 21 years after planting. Up to the 9th year, weed control had a greater influence on growth than fertilization. Later the significance of fertilization increased due to an aggravated K-deficiency. Stand volume at year 21 for the untreated control plots was 8 m3 ha–1. Weed control and fertilization increased stand volume by 20 and 35 m3 ha–1, with a combined effect of 55 m3 ha–1. The effects of weed control and fertilization were additive and no significant interactions were found. Due to severe K-deficiencies, re-fertilization of all treatments would be necessary for the continued survival and growth of Scots pine.

  • Hytönen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Teknologiakatu 7, FI-67100 Kokkola, Finland ORCID ID: http://orcid.org/0000-0001-8475-3568 E-mail: jyrki.hytonen@luke.fi (email)
  • Jylhä, Natural Resources Institute Finland (Luke), Green technology, Teknologiakatu 7, FI-67100 Kokkola, Finland ORCID ID:E-mail: paula.jylha@luke.fi
  • Little, Nelson Mandela Metropolitan University, George Campus, Western Cape, South Africa ORCID ID:E-mail: keith.little@nmmu.ac.za
article id 1721, category Research article
Anna Hebda, Błażej Wójkiewicz, Witold Wachowiak. (2017). Genetic characteristics of Scots pine in Poland and reference populations based on nuclear and chloroplast microsatellite markers. Silva Fennica vol. 51 no. 2 article id 1721. https://doi.org/10.14214/sf.1721
Highlights: Similar genetic variation was found between Polish Scots pine populations from a wide variety of habitats based on nSSR and cpSSR markers; Homogeneity was observed in the genetic structures of Polish and Finnish populations from the continuous pine range; Genetic differentiation in microsatellite markers was identified only when populations from the central pine distribution were compared to the marginal stands.

Polymorphisms at a set of eighteen nuclear (nSSR) and chloroplast (cpSSR) microsatellite loci were investigated in sixteen populations of Scots pine (Pinus sylvestris L.) derived from the provenance trial experiment and representative of the species distribution range and climatic zones in Poland. The patterns of genetic variation were compared to the reference samples from the species distribution in Europe and Asia. A similar level of genetic variation and no evidence of population structure was found among the Polish stands. They showed genetic similarity and homogenous patterns of allelic frequency spectra compared to the Northern European populations. Those populations were genetically divergent compared to the marginal populations from Turkey, Spain and Scotland. The population structure patterns reflect the phylogeography of the species and the divergence of populations that most likely do not share recent history. As the analysed provenance trial populations from Poland are diverged in phenotypic traits but are genetically similar, they could be used to test for selection at genomic regions that influence variation in quantitative traits.

  • Hebda, University of Agriculture in Krakow, Faculty of Forestry, Institute of Forest Ecology and Silviculture, Department of Genetics and Forest Tree Breeding, 29 Listopada 46, 31-425 Kraków, Poland ORCID ID: http://orcid.org/0000-0002-3149-8644 E-mail: ana.hebda@gmail.com (email)
  • Wójkiewicz, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland ORCID ID:E-mail: bwojkiew@man.poznan.pl
  • Wachowiak, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland; Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland ORCID ID:E-mail: witoldw@man.poznan.pl
article id 1692, category Research article
Aleksey Fedorkov, Ludmila Gutiy. (2017). Performance of lodgepole pine and Scots pine in field trials located in north-west Russia. Silva Fennica vol. 51 no. 1 article id 1692. https://doi.org/10.14214/sf.1692
Highlights: Stem volume was bigger for lodgepole pine in comparison to local Scots pine except for the southernmost origin; The proportion of stems with no defects was lower for all lodgepole pine seed sources than for local Scots pine; Lodgepole pine stem growth traits were significantly related to latitude of seed origin.

Mortality, stem growth and quality of lodgepole pine (Pinus contorta var. latifolia) originating from the six Swedish seed orchards and local Scots pine (Pinus sylvestris L.) were estimated in four field trials established in the Komi Republic (north-west Russia). A randomized row-plot design with 6–12 replicates of each entry was used. The tree mortality was slightly higher for Scots pine than that for lodgepole pine, except for the lodgepole pine seed sources of the southern origins with lower survival. Scots pine stem quality was better than that of lodgepole pine, but the lodgepole pine stem growth was faster except the seed source of the southernmost origin. The lodgepole pine seed sources of northern origins had better stem growth (height, diameter at breast height and volume), while the effect of latitude on the quality traits was insignificant.

  • Fedorkov, Institute of Biology, Komi Science Center, Russian Academy of Sciences, 28 Kommunisticheskaya st., Syktyvkar 167982, Russia ORCID ID: http://orcid.org/0000-0001-7800-7534 E-mail: fedorkov@ib.komisc.ru (email)
  • Gutiy, Syktyvkar Forest Institute (branch), Saint-Petersburg State Forest Technical University, 39 Lenin st., Syktyvkar 167000, Russia ORCID ID:E-mail: lguti@mail.ru
article id 1564, category Research article
Stanislav Vacek, Zdeněk Vacek, Lukáš Bílek, Jaroslav Simon, Jiří Remeš, Iva Hůnová, Jan Král, Tereza Putalová, Miroslav Mikeska. (2016). Structure, regeneration and growth of Scots pine (Pinus sylvestris L.) stands with respect to changing climate and environmental pollution. Silva Fennica vol. 50 no. 4 article id 1564. https://doi.org/10.14214/sf.1564
Highlights: Pine forest stands showed positive development of stand structural characteristics related to their diversity, number of regeneration individuals and growth characteristics; Tree-ring width was positively correlated with precipitation, while it was negatively correlated with temperature in growing seasons; Mean NOx concentrations showed positive effect on radial growth of pine; Serious defoliation was caused by SO2 concentrations and N deposition in combination with extreme climate events.

Changes in the structure and development of managed Scots pine (Pinus sylvestris L.) stands with respect to changing environmental conditions were set for the period 1979–2015. The study was conducted in conditions of natural pinewoods and pine-oak sites on five permanent research plots (0.25 ha) in Eastern Bohemia, Czech Republic (CR). Studied forest stands showed positive development of stand structural characteristics related to their diversity, number of regeneration individuals and growth characteristics. The standing volume of regularly distributed tree layer in 2015 was in the range of 320–434 m3 ha–1, which indicates an increase by 5.9–20.0% over 10 years. Correlation between pine radial increment and the amount of precipitation was generally the strongest one. Positive statistically significant correlation between diameter increment and temperature was demonstrated only for the average March temperature of the current year. Within the CR, study site can be characterised as a medium polluted area both for sulphur and nitrogen, despite this SO2 concentrations and N deposition in combination with extreme climate events caused severe defoliation in pine stands. Conversely, radial growth was positively significantly correlated with mean NOx concentrations. Drought mainly in combination with even medium environmental pollution can further worsen the health status of pine stands in lowland areas of Central Europe. Thus, formulation of silvicultural techniques able to mitigate the impact of these stress factors is needed.

  • Vacek, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic ORCID ID:E-mail: vacekstanislav@fld.czu.cz
  • Vacek, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic ORCID ID:E-mail: vacekz@fld.czu.cz
  • Bílek, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic ORCID ID:E-mail: bilek@fld.czu.cz
  • Simon, Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: jaroslav.simon@mendelu.cz
  • Remeš, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic ORCID ID:E-mail: remesj@email.cz (email)
  • Hůnová, Czech Hydrometeorological Institute, Na Šabatce 17 143 06 Prague, Czech Republic ORCID ID:E-mail: hunova@chmi.cz
  • Král, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic ORCID ID:E-mail: kraljan@fld.czu.cz
  • Putalová, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic ORCID ID:E-mail: putalova@fld.czu.cz
  • Mikeska, University of Hradec Králové, Faculty of Science, Rokitanského 62, 500 03 Hradec Králové, Czech Republic ORCID ID:E-mail: Mikeska.Miroslav@uhul.cz
article id 1565, category Research article
Teija Ruuhola, Ari Nikula, Nivala Vesa, Seppo Nevalainen, Juho Matala. (2016). Effects of bedrock and surficial deposit composition on moose damage in young forest stands in Finnish Lapland. Silva Fennica vol. 50 no. 3 article id 1565. https://doi.org/10.14214/sf.1565
Highlights: The effect of bedrock and soil on moose damage in forest plantations were examined; Moose damage were concentrated in nutrient rich bedrock areas; Bedrock of damaged stands contained a higher proportion of mafic and alkaline rocks; Pine-dominated stands on fine grained fertile forest sites had the highest damage risk.

There is evidence that moose are attracted to fertile growth habitats apparently due to better quality and larger quantities of food. The nutrients in mineral soils originate from the weathering of bedrock and the composition of parental bedrock affects the fertility of produced mineral soil, thus affecting also the import of nutrients into the whole food web. We surveyed the connection between moose damage in forest plantations and the composition of bedrock and surficial deposits in Finnish Lapland. We used a database of compensated moose damage in private forests in years 1997−2010. Undamaged stands in National Forest Inventories (NFI) from years 1986–2008 served as a control data and moose-damaged NFI-stands as a reference data. Bedrock and surficial depositions and the location of studied stands in relation to ancient shorelines were explored by using the digital databases of the Geological Survey of Finland. Moose-damaged stands were concentrated in southwestern and east Lapland in the areas of the Peräpohja Schist Belt and Lapland’s Greenstone Belt that are both composed of nutrient-rich rocks. The bedrock of damaged stands contained a higher proportion of mafic and alkaline rocks than did the control stands. Moose-damaged stands were pine-dominated and grew in more fertile forest sites than did control stands. Part of pine stands probably located in soils formerly occupied by spruce, which may increase the stands’ vulnerability to biotic threats. Especially, there were relatively more moose damage in pine plantations regenerated on fine-grained mineral soils derived from nutrient rich rocks than in less fertile soils.

  • Ruuhola, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Yliopistokatu 6, FI-80101 Joensuu, Finland; University of Eastern Finland, Faculty of Science and Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: teija.ruuhola@uef.fi
  • Nikula, Natural Resources Institute Finland (Luke), Economics and Society, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: ari.nikula@luke.fi (email)
  • Vesa, Natural Resources Institute Finland (Luke), Economics and Society, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: vesa.nivala@luke.fi
  • Nevalainen, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Yliopistokatu 6, FI-80101 Joensuu, Finland ORCID ID:E-mail: seppo.nevalainen@luke.fi
  • Matala, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Yliopistokatu 6, FI-80101 Joensuu, Finland ORCID ID:E-mail: juho.matala@luke.fi
article id 1562, category Research article
Mats Erik Berlin, Torgny Persson, Gunnar Jansson, Matti Haapanen, Seppo Ruotsalainen, Lars Bärring, Bengt Andersson Gull. (2016). Scots pine transfer effect models for growth and survival in Sweden and Finland. Silva Fennica vol. 50 no. 3 article id 1562. https://doi.org/10.14214/sf.1562
Highlights: Scots pine transfer effect models for growth and survival, valid in both Sweden and Finland have been developed; The models use high-resolution gridded climate data and can predict performance in future climatic conditions; The models perform well both for unimproved and genetically improved material and can be used to develop deployment recommendations of contemporary forest regeneration material in Sweden and Finland.

In this study, we developed models of transfer effects for growth and survival of Scots pine (Pinus sylvestris L.) in Sweden and Finland using a general linear mixed-model approach. For model development, we used 378 provenance and progeny trials with a total of 276 unimproved genetic entries (provenances and stand seed check-lots) distributed over a wide variety of climatic conditions in both countries. In addition, we used 119 progeny trials with 3921 selected genetic entries (open- and control pollinated plus-tree families) for testing model performance. As explanatory variables, both climatic indices derived from high-resolution gridded climate datasets and geographical variables were used. For transfer, latitude (photoperiod) and, for describing the site, temperature sum were found to be main drivers for both survival and growth. In addition, interaction terms (between transfer in latitude and site altitude for survival, and transfer in latitude and temperature sum for growth) entail changed reaction patterns of the models depending on climatic conditions of the growing site. The new models behave in a way that corresponds well to previous studies and recommendations for both countries. The model performance was tested using selected plus-trees from open and control pollinated progeny tests. Results imply that the models are valid for both countries and perform well also for genetically improved material. These models are the first step in developing common deployment recommendations for genetically improved forest regeneration material in both Sweden and Finland.

  • Berlin, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail: mats.berlin@skogforsk.se (email)
  • Persson, Skogforsk, Box 3, SE-91821 Sävar, Sweden ORCID ID:E-mail: torgny.persson@skogforsk.se
  • Jansson, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail: gunnar.jansson@skogforsk.se
  • Haapanen, Natural Resources Institute Finland (Luke), Green Technology, Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: matti.haapanen@luke.fi
  • Ruotsalainen, Natural Resources Institute Finland (Luke), Green Technology, Finlandiantie 18, FI-58450 Punkaharju, Finland ORCID ID:E-mail: seppo.ruotsalainen@luke.fi
  • Bärring, Rossby Centre, Swedish Meteorological and Hydrological Institute, Folkborgsvägen 17, SE-60176 Norrköping, Sweden ORCID ID:E-mail: lars.barring@smhi.se
  • Andersson Gull, Skogforsk, Box 3, SE-91821 Sävar, Sweden ORCID ID:E-mail: bengt.andersson@skogforsk.se
article id 1514, category Research article
Heidi Hallongren, Ville Kankaanhuhta, Mikael Kukkonen. (2016). Cleaning Scots pine seedling stands with mechanical uprooters – a work quality comparison of two related devices. Silva Fennica vol. 50 no. 3 article id 1514. https://doi.org/10.14214/sf.1514
Highlights: The productivity of the narrower modified device was significantly better than the wider original device; Work quality did not differ significantly between devices when stand characteristics, regeneration success and pre-existing damage were taken into account; Results indicate that mechanical uprooting devices may be further developed to a cost-effective alternative to motor-manual techniques for the early cleaning of direct seeded commercial Scots pine stands.

Commercial forests require early cleaning to ensure the unhindered and uniform growth of crop trees. In order to be cost effective, non-crop vegetation should be uprooted to prevent their recovery. Performing this work manually is a labour-intensive task but it can be done mechanically. We evaluated the efficiency of two uprooting devices in direct seeded Scots pine (Pinus sylvestris L.) stands ca. 1 m tall. Productivity and quality of the uprooting work was investigated across eight stands and ca. 160 sample plots in northern Karelia, eastern Finland. Time consumption of the uprooters was analyzed through a linear regression model and the work quality through a multilevel multivariate model in terms of the number of individual Scots pine seedlings, processing units (i.e., a bunch of seedlings to be harvested in the future) and broadleaves. The productivity of the narrower modified device was significantly better in terms of time consumption than the wider original device. Work quality did not differ significantly between devices when stand characteristics, regeneration success and pre-existing damage were taken into account. Results indicate that mechanical uprooting devices may be further developed to a cost-effective alternative to motor-manual techniques for the early cleaning of direct seeded commercial Scots pine stands.

  • Hallongren, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: heidi.hallongren@luke.fi (email)
  • Kankaanhuhta, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: ville.kankaanhuhta@luke.fi
  • Kukkonen, University of Eastern Finland, School of Forest Sciences. P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: mikaelkukkonen@hotmail.com
article id 1441, category Research article
Dorota Zawadzka, Stanisław Drozdowski, Grzegorz Zawadzki, Jerzy Zawadzki. (2016). The availability of cavity trees along an age gradient in fresh pine forests. Silva Fennica vol. 50 no. 3 article id 1441. https://doi.org/10.14214/sf.1441
Highlights: The density of cavity trees in pine-dominated, managed forests varied in relation to stand age and was highest in stands older than 130 years of age; Cavities excavated by woodpeckers dominated among all cavities; The number of trees with cavities appears insufficient to ensure the effective protection of bird diversity in managed stands of Augustów Forest.

Given their importance as a resource for many forest organisms, tree cavities were inventoried in the managed pine forests of north-east Poland, in relation to the: 70–100, 101–130 and >130 year age-classes within the clear-cutting system. The densities at which cavities were present was found to depend on forest age, given that stands 70–100 years old were characterised by an average density of 0.62 trees ha–1, while forests older than 130 years reported 3.28 trees ha–1. Stands aged 70–100 years differed from those aged 130+ in having just 0.27 trees ha–1 of cavity trees, as compared with 2.91 trees ha–1. The total volume of cavity trees in stands up to 100 years old was 0.37 m3 ha–1 on average, as compared with 5.42 m3 ha–1 in stands over 130 years old. The cavities created by woodpeckers constituted 76% of all of those found, and included 53% excavated by great spotted woodpeckers (Dendrocopos major L.) and 23% by black woodpeckers (Dryocopus martius L.) The proportion of cavities excavated by D. major was highest in the youngest age class of stands. There, cavities made by D. martius constituted only 8% of the total, as compared with 31% in the oldest stands. The abundance of cavity trees thus differed along an age gradient, though in any event the availability of cavity trees appears to be too limited to provide for the needs of hole-nesting birds. Forest managers must thus take more account than hitherto of the need to protect cavity trees.

  • Zawadzka, Institute of Forest Science, University of Łódź, Branch in Tomaszów Mazowiecki, Konstytucji 3 Maja 65/67, 97-200 Tomaszów Mazowiecki, Poland ORCID ID:E-mail: dorota_zaw@wp.pl
  • Drozdowski, Department of Silviculture, Warsaw University of Life Sciences - SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland ORCID ID:E-mail: stanislaw_drozdowski@sggw.pl (email)
  • Zawadzki, Eagle Conservation Committee, Okółek 14, 16-506 Giby, Poland ORCID ID:E-mail: grzesiekgfz@op.pl
  • Zawadzki, Eagle Conservation Committee, Okółek 14, 16-506 Giby, Poland ORCID ID:E-mail: jerzy_zaw@wp.pl
article id 1410, category Research article
Seppo Nevalainen, Juho Matala, Kari T. Korhonen, Antti Ihalainen, Ari Nikula. (2016). Moose damage in National Forest Inventories (1986–2008) in Finland. Silva Fennica vol. 50 no. 2 article id 1410. https://doi.org/10.14214/sf.1410
Highlights: Almost 100 000 stands were studied; The proportion of damage doubled during the study period; Tree species mixture had a clear effect on the damage frequency; The damage was more common in mineral soils than in peatlands, in artificially than in naturally regenerated stands and in stands that needed thinning or clearing or in which soil preparation was used.

The occurrence of moose damage was studied using data from three National Forest Inventories (NFIs) accomplished between 1986 and 2008 in Finland. The combined data included a total of 97 390 young stands. The proportion of moose damage increased from 3.6% to 8.6% between the 8th NFI (1986–1994) and the 10th NFI (2004–2008). The majority (75%) of the damage occurred in Scots pine-dominated stands. The proportion of damage was higher in aspen-dominated stands than in stands dominated by any other tree species. The tree species mixture also had a clear effect on the occurrence of damage. Pure Scots pine stands had less damage than mixed Scots pine stands, and moose damage decreased linearly with the increasing proportion of Scots pine. Stands on mineral soil had more frequent moose damage than stands on peatlands. The fertility class of the site had no straightforward effect on the damage frequency. Artificially regenerated stands had more damage than naturally regenerated stands. Accomplished soil preparation measures and the need for thinning or clearing operations increased moose damage. High proportions of moose damage in young stands were found around the country. In the 10th NFI, the largest concentration of damage was found in southwestern Finland. Our study shows the temporal and spatial changes in the occurrence of moose damage and pinpoints some important silvicultural factors affecting the relative risk of young stands over a large geographical area.

  • Nevalainen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: seppo.nevalainen@luke.fi (email)
  • Matala, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: juho.matala@luke.fi
  • Korhonen, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: kari.t.korhonen@luke.fi
  • Ihalainen, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: antti.ihalainen@luke.fi
  • Nikula, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: ari.nikula@luke.fi
article id 1408, category Research article
Anna Katharina Franke, Pasi Aatsinki, Ville Hallikainen, Esa Huhta, Mikko Hyppönen, Vesa Juntunen, Kari Mikkola, Seppo Neuvonen, Pasi Rautio. (2015). Quantifying changes of the coniferous forest line in Finnish Lapland during 1983–2009. Silva Fennica vol. 49 no. 4 article id 1408. https://doi.org/10.14214/sf.1408
Highlights: Volume of the growing stock of spruce and pine has increased in forests and in timber lines during the past 26 years; Spruce stem numbers increased on average, while pine stem numbers remained stable and location-specific variation was observed; Presuming that the ongoing trend of increasing temperature will remain, the enhanced forest regeneration and growth may result in extension of forests in the future.

The boreal timber- and tree-line forests grow in harsh environmental conditions in their outermost distribution limit. Here even small environmental changes may cause dramatic changes in the distribution of tree species. We examined changes of the forest lines of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) in Finnish Lapland five times during 1983–2009. We monitored the number of stems and the volume of the growing stock in thirteen different locations in forest-line areas. The linear temporal trends and the variations of these response variables were used as indicators of a possible change during the study period. Spruce showed a significant increase both in the volume of the growing stock (up to 40% increase) and in the total stem number (up to 100% increase). A significant increase in the volume of the growing stock was observed in the pine data as well (up to 70% increase), whereas the stem number stagnated or even decreased. The results suggest that spruce needs favourable conditions to have an abundant regeneration, but after the establishment the seedlings seem to be more resistant against biotic and abiotic disturbances than pine seedlings. The increasing stand volume might result in a climate-related northward and upward extension of forests in the future. However, our results show that responses in the boreal forest line are species and location specific and a more favourable climate does not necessarily lead to an advance of the coniferous forest line.

  • Franke, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: anna.franke@fau.de (email)
  • Aatsinki, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: pasi.aatsinki@luke.fi
  • Hallikainen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: ville.hallikainen@luke.fi
  • Huhta, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: esa.huhta@luke.fi
  • Hyppönen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: mikko.hypponen@luke.fi
  • Juntunen, The Sámi Education Institute, Menesjärventie 4, P.O. Box 50, FI-99871 Inari, Finland ORCID ID:E-mail: vesa.juntunen@sogsakk.fi
  • Mikkola, Natural Resources Institute Finland (Luke), Economics and society, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: kari.mikkola@luke.fi
  • Neuvonen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 68, FI-80101, Joensuu, Finland ORCID ID:E-mail: seppo.neuvonen@luke.fi
  • Rautio, Natural Resources Institute Finland (Luke), Bio-based business and industry, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: pasi.rautio@luke.fi
article id 1354, category Research article
Johannes Edvardsson, Anton Hansson. (2015). Multiannual hydrological responses in Scots pine radial growth within raised bogs in southern Sweden. Silva Fennica vol. 49 no. 4 article id 1354. https://doi.org/10.14214/sf.1354
Highlights: Annual growth of Scots pine (Pinus sylvestris L.) at Boreal raised bogs was found to reflect a synthesis of climate controlled moisture variability over the preceding one to four year period; Excessive soil moisture is a growth limiting factor for trees at raised bogs; River discharge data reflect hydrological conditions in peat bogs better than precipitation data.

To explore interactions between climate and peatland hydrology, Scots pine (Pinus sylvestris L.) growing at four raised bogs in southern Sweden were subject to a dendroclimatological study. Radial tree growth reflecting climate and water table fluctuations over multiannual periods was detected as significant negative correlations between tree-ring width (TRW) chronologies and the preceding one to four years total precipitation or river discharge. Systematically stronger negative correlations were obtained when river discharge instead of precipitation was compared to radial tree growth. This indicates that river discharge reflect moisture variability of peat bogs better than what precipitation data does. Meanwhile, monthly precipitation and radial tree growth did not show any clear correlation, whereas spring and early summer temperatures had a positive influence on the tree growth. Our study shows that growth variability of bog pines in the Boreal zone reflect hydrological responses related to a synthesis of climate controlled moisture variability over several year periods.

  • Edvardsson, Dendrolab.ch, Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, CH-3012 Bern, Switzerland & Quaternary Sciences, Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden ORCID ID: http://orcid.org/0000-0001-5163-1599 E-mail: johannes.edvardsson@dendrolab.ch (email)
  • Hansson, Quaternary Sciences, Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden ORCID ID:E-mail: anton.hansson@geol.lu.se
article id 1301, category Research article
Mikko Moilanen, Jyrki Hytönen, Hannu Hökkä, Anssi Ahtikoski. (2015). Fertilization increased growth of Scots pine and financial performance of forest management in a drained peatland in Finland. Silva Fennica vol. 49 no. 3 article id 1301. https://doi.org/10.14214/sf.1301
Highlights: All fertilizers containing phosphorus and potassium improved the P and K status and the stem growth of Scots pine still 26 years from application; Wood ash, containing more nutrients than other fertilizers, gave the strongest stand growth response and the highest net present value; Ash fertilizer treatment outperformed other fertilizer treatments and control in net present value, regardless of the applied discount rate, 3%, 4% or 5%.

The long-term effects of fertilization on the needle nutrient concentrations, growth and financial performance of a Scots pine (Pinus sylvestris L.) stand was examined in a thick-peated drained peatland forest located in Central Finland. At the trial establishment in 1985, the trees were suffering from P and K deficiencies, but their N status was good. The fertilizer treatments were Control, PK (rock phosphate + potassium chloride), ApaBio (apatite phosphorus + biotite) and wood ash, applied both with and without N and replicated six times. All treatments containing phosphorus and potassium increased foliar P and K concentrations above the deficiency limits up to the end of the study period of 26 years. The effect of the fertilization on stand volume growth of Scots pine was strong and continued still at the end of the study period. The trees on ApaBio and PK plots grew nearly two-fold and those on Ash plots over two-fold compared with the control plots. In a thinning made at the end of the study period the total logging removal on fertilized plots was 1.5–2.2 times greater and included more saw logs than on the control plots. Ash fertilizer treatment outperformed other fertilizer treatments as well as the control. With a 5% discounted equivalent annual income (EAI) of Ash fertilizer treatment was statistically significantly (p=0.009) almost three times higher than that of control. As a conclusion, fertilization (either using PK fertilizers or Ash) in N-rich drained peatlands is a financially feasible method of management.

  • Moilanen, Natural Resources Institute Finland, Natural resources and bioproduction, Paavo Havaksen tie 3, FI-90014 Oulu, Finland ORCID ID:E-mail: mikko.moilanen@luke.fi (email)
  • Hytönen, Natural Resources Institute Finland, Natural resources and bioproduction, Silmäjärventie 2, FI-69100 Kannus, Finland ORCID ID:E-mail: jyrki.hytonen@luke.fi
  • Hökkä, Natural Resources Institute Finland, Natural resources and bioproduction, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: hannu.hokka@luke.fi
  • Ahtikoski, Natural Resources Institute Finland, Natural resources and bioproduction, Paavo Havaksen tie 3, FI-90014 Oulu, Finland ORCID ID:E-mail: anssi.ahtikoski@luke.fi
article id 1262, category Research article
Āris Jansons, Roberts Matisons, Māra Zadiņa, Linards Sisenis, Jānis Jansons. (2015). The effect of climatic factors on height increment of Scots pine in sites differing by continentality in Latvia. Silva Fennica vol. 49 no. 3 article id 1262. https://doi.org/10.14214/sf.1262
Highlights: Height increment-climate relationships of Scots pine were assessed using dendrochronological techniques; Annual height increment was significantly affected by climatic factors; In western Latvia, temperature in preceding summer mainly affected height increment; In eastern Latvia height increment was affected by previous autumn temperature; During the 20th century, the effect of climatic factors has altered likely dues to climate change.
Height growth of trees is a crucial parameter that influences the composition and productivity of forest stands and quality of timber; however, the relationships between annual height increment (HI) and climatic factors have been poorly studied. In this study, the effect of monthly mean temperature and precipitation sums on the HI of Scots pine in two sites in Latvia have been determined using dendrochronological techniques. Correlation and response function analyses were conducted for entire chronologies of HI and for 50-year intervals within them. Climatic factors significantly affected the HI of Scots pine; however, not only did the suite of significant factors differ between the sites, but the influence of these factors changed during the 20th century. In the site in western Latvia where climate is milder, temperature in the preceding summer was the main climatic determinant of HI. The effect of temperature in the dormant period and spring was significant during the first part of the 20th century, while the effect of temperature in the previous September and November has become significant since the second half of the 20th century. In the site in eastern Latvia where summers are hotter, HI has been affected by both temperature and water deficit related factors in the summer. However, since the later part of the 20th century, the effect of temperature in the previous October has intensified and become the main climatic determinant of HI.
  • Jansons,  LSFRI “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: aris.jansons@silava.lv
  • Matisons,  LSFRI “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: robism@inbox.lv (email)
  • Zadiņa,  LSFRI “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: mara.zadina@silava.lv
  • Sisenis, LUA Forestry Faculty, Akadēmijas str. 11, Jelgava, Latvia ORCID ID:E-mail: linards.sisenis@llu.lv
  • Jansons, Forest Competence Centre, Dzērbenes str. 27, Riga, Latvia, LV1006 ORCID ID:E-mail: janis.jansons@silava.lv
article id 1220, category Research article
Elisabeth Düthorn, Lea Schneider, Oliver Konter, Philipp Schön, Mauri Timonen, Jan Esper. (2015). On the hidden significance of differing micro-sites on tree-ring based climate reconstructions. Silva Fennica vol. 49 no. 1 article id 1220. https://doi.org/10.14214/sf.1220
Highlights: Pines and spruces show growth level differences in wet and dry micro-sites with higher growth rates in the dry sites; Spruces show a robust climate-growth relationship with June-July temperatures; Application of collective detrending methods can bias long-term trends in climate reconstructions, if relict and recent samples originate from different micro-sites.
Tree-ring chronologies are commonly extended back in time by combining samples from living trees with relict material preserved in man-made structures or natural archives (e.g. lakes). Although spatially close, these natural archives and living-tree-sites often comprise different micro-climates. Inhomogeneous growth conditions among these habitats, which may yield offsets in growth-rates, require caution in data processing. Here we assess species-specific growth dynamics in two micro-habitats and their potential effects on long chronologies by combining tree-ring data from different living-tree-sites with an “artificial” subfossil dataset. Well replicated (n > 80) Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) chronologies from northern Fennoscandia, sampled directly at the lakeshore (wet) and several meters beyond the lakeshore (dry) reveal high coherence of the variance between micro-sites (rspruce = 0.59, rpine = 0.68). Significant differences of the Regional Curves (RC) indicate faster growth of both species at the drier site though. Growth differences are more pronounced between the spruce micro-sites. The combination of recent dry and wet spruce data with artificial relict data results in two long chronologies covering the last 800 years with substantially different trends, although they consist of the same relict material and the micro-site chronologies correlate significantly over the past two centuries. The combination of spruce samples from dry inland micro-sites with subfossil samples originating from the wet lake shore can result in an underestimation of past temperatures prior to the 19th century. Such effects, hidden in the composition of long chronologies (living trees + subfossil samples) can bias long-term trends in climate reconstructions.
  • Düthorn, Department of Geography, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany ORCID ID:E-mail: duethorn@uni-mainz.de (email)
  • Schneider, Department of Geography, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany ORCID ID:E-mail: l.schneider@geo.uni-mainz.de
  • Konter, Department of Geography, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany ORCID ID:E-mail: O.Konter@geo.uni-mainz.de
  • Schön, Department of Geography, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany ORCID ID:E-mail: philipp.schoen@gmx.de
  • Timonen, Natural Resources Institute Finland (Luke), Natural resources and bioproduction, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: mauri.timonen@metla.fi
  • Esper, Department of Geography, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany ORCID ID:E-mail: J.Esper@geo.uni-mainz.de
article id 1119, category Research article
Beata Woziwoda, Agnieszka Parzych, Dominik Kopeć. (2014). Species diversity, biomass accumulation and carbon sequestration in the understorey of post-agricultural Scots pine forests. Silva Fennica vol. 48 no. 4 article id 1119. https://doi.org/10.14214/sf.1119
Highlights: Understorey plant species diversity significantly increases with the age of a Scots pine stand; Biomass of mosses decreases by a quarter, while biomass of herbs increases several times; Total understorey’s carbon stock increases over three times. The highest amount of carbon is accumulated in understorey species like Vaccinium myrtillus and Dicranum polysetum; The growing proportion of vascular plants in the understorey biomass results in an increase in the understorey C/N ratio.
The purpose of this study was to examine how the age of a stand of post-agricultural Scots pine forests affects the species composition, biomass and the carbon stock of the forest understorey. The community structure and species composition were studied in 75 plots (100 m2 in size), the amount of biomass, organic carbon and total nitrogen were analysed in 75 subplots (1/16 m2 in size). The plots were located in 21 plantations with the stand age of 41–60, 61–80 and over 80-years. Results show that the understorey species diversity increased with the increasing age of Scots pine stands, and the structure and species composition of secondary forests (although managed for timber production) became similar to the fresh pine forest of the European temperate region (Leucobryo-Pinetum community). Despite the increasing species diversity, however, only six understorey vascular and moss species played an important role in the biomass accumulation and C sequestration. Due to the differences in the dominant species composition, the total amount of understorey biomass significantly differed among the forest stands. The mean moss biomass ranged from 3046 kg ha–1 in 41–60-year-old stands, trough 2686 kg ha–1 in 61–80-year-old stands to 2273 kg ha–1 in over 80-year-old stands, and the mean understorey vascular plant biomass amounted to 2 kg ha–1, 1924 kg ha–1 and 3508 kg ha–1, respectively. The concentration of organic C varied considerably between species; it was the highest in Vaccinium myrtillus (50.6%) and in Dicranum polysetum (49.5%). The total mass of C was nearly 800 kg ha–1 in the youngest forests, in the subsequent age series it was two times higher and 3.5 times higher in the oldest ones. Differences in the species composition and in the C/N ratio in different species (generally higher for vascular plants and lower for mosses) were expressed in an increase in the understorey C/N ratio, which was 39.5, 46.6 and 48.6, respectively.
  • Woziwoda, Department of Geobotany and Plant Ecology, Faculty of Biology and Environmental Protection, University of Lodz, Banacha 12/16, 90-237 Lodz, Poland ORCID ID:E-mail: woziwoda@biol.uni.lodz.pl (email)
  • Parzych, Environmental Chemistry Research Unit, Institute of Biology and Environmental Protection, Pomeranian University in Słupsk, Arciszewskiego 22b, 76-200 Słupsk, Poland ORCID ID:E-mail: parzycha1@op.pl
  • Kopeć, Department of Geobotany and Plant Ecology, Faculty of Biology and Environmental Protection, University of Lodz, Banacha 12/16, 90-237 Lodz, Poland ORCID ID:E-mail: domin@biol.uni.lodz.pl
article id 989, category Research article
Anna Saarsalmi, Pekka Tamminen, Mikko Kukkola. (2014). Effects of long-term fertilisation on soil properties in Scots pine and Norway spruce stands. Silva Fennica vol. 48 no. 1 article id 989. https://doi.org/10.14214/sf.989
Highlights: N fertilisation increased the amount of carbon in the organic layer; N fertilisation decreased the C/N ratio in the surface soil; N addition increased the amount of most nutrients in the organic layer; N fertilisation tended to lower pH, although only slightly.
The response of surface soil after 45- to 52-years to repeated nitrogen and phosphorus fertilisation was studied. This study included 30 factorial experiments established in young (5- to 30-year-old) stands using plots of 900 m2, on average, and by randomising treatments within each experiment. Total amount of N added varied from 534 to 1908 kg ha–1 and that of P from 69 to 193 kg ha–1, repeated at every second N fertilisation. Liming was performed twice; in total, 6000 kg ha–1 of dolomite was applied. Nitrogen fertilisation increased the mass of the organic layer and the amount of carbon and consequently the amounts of most of the elements in the organic layer. In both the organic layer and the 0–10 cm layer of mineral soil, nitrogen fertilisation decreased the C/N ratio and tended to lower pH, although only slightly. Phosphorus fertilisation increased the amounts of P and Ca. Liming increased the total amounts of most elements in the organic layer, except for C and N. We were able to derive models to describe how changes in the chemical properties of the surface soil depended on doses of elements and on site and stand properties.
  • Saarsalmi, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: anna.saarsalmi@metla.fi (email)
  • Tamminen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: pekka.tamminen@metla.fi
  • Kukkola, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: mikko.kukkola@metla.fi
article id 441, category Research article
Ane Zubizarreta-Gerendiain, Petri Pellikka, Jordi Garcia-Gonzalo, Veli-Pekka Ikonen, Heli Peltola. (2012). Factors affecting wind and snow damage of individual trees in a small management unit in Finland: assessment based on inventoried damage and mechanistic modelling. Silva Fennica vol. 46 no. 2 article id 441. https://doi.org/10.14214/sf.441
In this work, we assessed the factors affecting wind and snow damage of individual trees in a small management unit in western Finland. This was done based on inventoried damage and observed wind speeds and snow loading in storms Pyry and Janika in 2001 and Mielikki in 2002 together with mechanistic model. First, we studied which factors explain the observed damage in individual trees. Secondly, we studied how well the mechanistic model (HWIND) could predict the wind speed needed to uproot individual trees at the margins of permanent upwind edges. We found that Pyry storm caused 70% and Janika and Mielikki 18 and 12% of observed damage. In Janika storm, all trees uprooted. In other storms, both uprooting and stem breakage occurred. Scots pine suffered the most damage. Recently thinned stands on the upwind edges of open areas suffered the most damage. But, damage occurred also on soils with relatively shallow anchorage. HWIND predicted correctly damage for 69% of all uprooted trees. No-uprooting was correctly predicted for 45 and 19% of standing trees (all Scots pines), which were measured within and at the immediate upwind edge of same stands. HWIND model needs further validation at the permanent edges and/or on soils with shallow rooting to improve its prediction accuracy in such conditions.
  • Zubizarreta-Gerendiain, Technical University of Lisbon, School of Agriculture, Forest Research Centre, Lisbon, Portugal ORCID ID:E-mail:
  • Pellikka, University of Helsinki, Dept. of Geosciences and Geography, Helsinki, Finland ORCID ID:E-mail:
  • Garcia-Gonzalo, Technical University of Lisbon, School of Agriculture, Forest Research Centre, Lisbon, Portugal ORCID ID:E-mail:
  • Ikonen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
  • Peltola, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail: heli.peltola@uef.fi (email)
article id 54, category Research article
Urban Nilsson, Björn Elfving, Kjell Karlsson. (2012). Productivity of Norway spruce compared to Scots pine in the interior of northern Sweden. Silva Fennica vol. 46 no. 2 article id 54. https://doi.org/10.14214/sf.54
Productivity of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) was studied in 12 paired plots in the interior of northern Sweden. Stands were established between 1928 and 1959; yield plots were established between 1974 and 1983 during pre-commercial thinning of the stands. Gross stem-wood production was significantly higher for Scots pine than for Norway spruce, stem-wood production by Norway spruce being 29.4% that of Scots pine. The site index for Norway spruce was lower than for Scots pine at all sites except one; the average difference in site index was 4.8 m. The simulated maximum mean annual increment (MAImax) during the rotation was 19% higher than the MAImax estimated with the site index for Scots pine, whereas simulated MAImax and MAImax estimated from the site index was about the same for Norway spruce. The simulations also indicated that MAI peaked about 50 years later for Norway spruce than for Scots pine. More small trees were included in the diameter distribution of Norway spruce than of Scots pine resulting in a lower stem-wood volume for Norway spruce when stands with the same dominant height were compared. This study shows that the difference in growth and rotation length between Scots pine and Norway spruce has implications when choosing which species to grow in the interior of northern Sweden.
  • Nilsson, Swedish University of Agricultural Sciences (SLU), Southern Swedish Forest Research Centre, Alnarp, Sweden ORCID ID:E-mail: urban.nilsson@slu.se (email)
  • Elfving, SLU, Forest Ecology and Management, Umeå, Sweden ORCID ID:E-mail:
  • Karlsson, SLU, Unit of Field Based Research, Asa, Sweden ORCID ID:E-mail:
article id 99, category Research article
Jouni Siipilehto. (2011). Local prediction of stand structure using linear prediction theory in Scots pine-dominated stands in Finland. Silva Fennica vol. 45 no. 4 article id 99. https://doi.org/10.14214/sf.99
This study produced a family of models for eight standard stand characteristics, frequency and basal area-based diameter distributions, and a height curve for stands in Finland dominated by Scots pine (Pinus sylvestris L.). The data consisted of 752 National Forest Inventory-based sample plots, measured three times between 1976 and 2001. Of the data, 75% were randomly selected for modelling and 25% left out for model evaluation. Base prediction models were constructed as functions of stand age, location and site providing strongly average expectations. These expectations were then calibrated with the known stand variables using linear prediction theory when estimating the best linear unbiased predictor (BLUP). Three stand variables, typically assessed in Finnish forest management planning fieldwork, were quite effective for calibrating the expectation for the unknown variable. In the case of optional distributions, it was essential to choose the weighting of the diameter distribution model such that the available input variables and the model applied were based on the same scale (e.g. arithmetic stand variables for frequency distribution). Additional input variables generally improved the accuracy of the validated characteristics, but the improvements in the predicted distributions were most noteworthy when the arithmetic mean and basal area-weighted median were simultaneously included in the BLUP estimation. The BLUP method provided a flexible approach for characterising relationships among stand variables, alternative size distributions and the height–diameter curve. Models are intended for practical use in the MOTTI simulator.
  • Siipilehto, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: jouni.siipilehto@metla.fi (email)
article id 93, category Research article
Pertti Pulkkinen, Saila Varis, Raimo Jaatinen, Aulis Leppänen, Anne Pakkanen. (2011). Increasing survival and growth of Scots pine seedlings with selection based on autumn coloration. Silva Fennica vol. 45 no. 4 article id 93. https://doi.org/10.14214/sf.93
This study evaluates the possibility of using autumn coloration of young Scots pine (Pinus sylvestris L.) seedlings as an indicator of adaptation to harsh climate conditions. One-year old seedlings from natural stands with different origins and seed orchards were classified as “red/reddish” and “green” based on the needle color after artificially increased night length in nursery and then measured after 14 years in field trials. In almost all the studied groups seedlings classified as “red/reddish” had significantly higher survival rate than seedlings classified as “green”. The survival of “red/reddish” was 14.2% higher than “green” among natural stand seed material and 56.2% among seed orchard material. During the study period the survival difference between “red/reddish” and “green” seedlings tended to increase. The seedling color had limited connection with the height growth, even though the trees classified as “red/reddish” were slightly taller than those classified as “green”. However, the total productivity over all field trials, described here as a heightsum, of “red/reddish” trees was 15% higher than productivity of “green” trees from natural stand material, and 61% higher than those from seed orchard material. It seems that controlled selection based on autumn color can be utilized within seed crops of different types with the aim to increase the adaptability of seed material to different environmental conditions.
  • Pulkkinen, Metla, Haapastensyrjä, Läyliäinen, Finland ORCID ID:E-mail: pertti.pulkkinen@metla.fi (email)
  • Varis, Metla, Haapastensyrjä, Läyliäinen, Finland ORCID ID:E-mail:
  • Jaatinen, Metla, Haapastensyrjä, Läyliäinen, Finland ORCID ID:E-mail:
  • Leppänen, Metla, Haapastensyrjä, Läyliäinen, Finland ORCID ID:E-mail:
  • Pakkanen, Metla, Haapastensyrjä, Läyliäinen, Finland ORCID ID:E-mail:
article id 104, category Research article
Eeva Terhonen, Teresa Marco, Hui Sun, Risto Jalkanen, Risto Kasanen, Martti Vuorinen, Fred Asiegbu. (2011). The effect of latitude, season and needle-age on the mycota of Scots pine (Pinus sylvestris) in Finland. Silva Fennica vol. 45 no. 3 article id 104. https://doi.org/10.14214/sf.104
The seasonal and latitudinal influences on the diversity and abundance of mycota of Pinus sylvestris needles were investigated. A sample of 1620 needles resulted in a total of 3868 fungal isolates, which were assigned to 68 operational taxonomic units (OTUs). The majority of these OTUs (65%) belong to Ascomycota and only 0.03% was grouped as Basidiomycota. The dominant and most frequently isolated OTU was Hormonema dematioides. Other well-known species with a saprotrophic nutritional mode such as Lophodermium spp. were also observed. The abundance of fungi increased from fall to spring. Frequencies varied significantly in Northern and Southern Finland suggesting that factors associated with latitudinal differences have an impact on the abundance of fungi.
  • Terhonen, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Marco, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Sun, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, Rovaniemi, Finland ORCID ID:E-mail:
  • Kasanen, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Vuorinen, Finnish Forest Research Institute, Suonenjoki Research Unit, Suonenjoki, Finland ORCID ID:E-mail:
  • Asiegbu, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
article id 29, category Research article
Piotr Androsiuk, Roman Zielinski, Kornelia Polok. (2011). B-SAP markers derived from the bacterial KatG gene differentiate populations of Pinus sylvestris and provide new insights into their postglacial history. Silva Fennica vol. 45 no. 1 article id 29. https://doi.org/10.14214/sf.29
The aim of the studies was to evaluate the efficiency of the KatG gene based B-SAP markers as a tool to distinguish morphologically diversified and geographically distant Scots pine populations and to track the routes of migrations. The 19 populations growing in the IUFRO 1982 provenance experiment and representing the natural distribution of the species in Europe were scored using 103 B-SAP loci. Among them 26% loci were polymorphic. The level of polymorphism was associated with the location of primers on the KatG template. The diversity was low, He = 0.086, and deposited mostly among populations. Seven unique markers were found that identified populations and likely they were associated with morphology. The overall genetic identity was relatively low, I = 0.933 (D = 0.069). The block of six B-SAP markers discriminated populations into two groups in agreement with their geographic origin and thereby further described as the North and the South. The North group was uniform with genetic diversity, He = 0.026 and the overall genetic distance D = 0.022. Presumably, it migrated from refugia in the Alps via France, northern Germany and Denmark, to Scandinavia and Russia. The South group was heterogeneous with He = 0.063 and D = 0.047. This group migrated from the Carpathians via Slovakia to Germany and Poland. The Balkans and Asian refugia did not take part in recolonization of Europe. The block of six B-SAP/KatG markers can be recommended for tracking postglacial history of Scots pine.
  • Androsiuk, University of Warmia and Mazury in Olsztyn, Department of Genetics, Plac Lodzki 3, 10-967 Olsztyn, Poland ORCID ID:E-mail:
  • Zielinski, University of Warmia and Mazury in Olsztyn, Department of Genetics, Plac Lodzki 3, 10-967 Olsztyn, Poland ORCID ID:E-mail:
  • Polok, University of Warmia and Mazury in Olsztyn, Department of Genetics, Plac Lodzki 3, 10-967 Olsztyn, Poland ORCID ID:E-mail: kpolok@moskit.uwm.edu.pl (email)
article id 123, category Research article
Staffan Jacobson, Folke Pettersson. (2010). An assessment of different fertilization regimes in three boreal coniferous stands. Silva Fennica vol. 44 no. 5 article id 123. https://doi.org/10.14214/sf.123
In 1981–82 three field experiments were established with the aim of elucidating (i) the growth response of middle-aged coniferous stands at different fertilization intensities and, hence, the economic outcomes; and (ii) the need to add nutrients other than nitrogen (N). Nutrient additions were performed at intervals of two, four, six and eight years. The experiments were established on typical podzolized and N-limited mor-humus sites, two in Scots pine (Pinus sylvestris L.) stands and one in a Norway spruce (Picea abies (L.) Karst.) stand, at three different locations in Sweden. The ages of the stands were 65–70 years at the time of establishment. Growth responses were calculated after a 22-year study period. The growth responses were significant in all treatments. The addition of nutrients other than N did not affect stem growth at any of the sites. The growth response tended to increase with decreasing application interval. The results also revealed that the efficiency of fertilization is reduced as the interval between fertilizations is shortened. Accordingly, the growth effect per kg of added N was negatively correlated to fertilization intensity. The least intensive fertilization regime (an eight-year interval) resulted in an average net increase in C sequestration of 35 kg per kg N added. The profitability, in terms of internal rate of return, the present net value at different interest rates and the cost of production, i.e. the cost to produce one extra m3 under the different N regimes, are presented and discussed.
  • Jacobson, Skogforsk, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail: staffan.jacobson@skogforsk.se (email)
  • Pettersson, Skogforsk, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail:
article id 132, category Research article
Mats Berlin, Lars Lönnstedt, Gunnar Jansson, Öje Danell, Tore Ericsson. (2010). Developing a Scots pine breeding objective: a case study involving a Swedish sawmill. Silva Fennica vol. 44 no. 4 article id 132. https://doi.org/10.14214/sf.132
The aim of this study was to develop a Scots pine (Pinus sylvestris L.) breeding objective for a vertically integrated sawmill in northern Sweden. The production system was defined as comprising the sawmill and the forests supplying it. Volume per hectare, wood density, survival and straightness were used as objective traits and the related selection criteria were measurements, collected at young tree age, of height, diameter, pilodyn penetration, vitality and straightness. A bio-economic model was used to calculate economic weights for the objective traits identified. We also investigated the efficiency of different selection indices based on these economic weights, in combination with available data on genetic parameters. Furthermore, we studied the effect of different discount rates on the calculated economic weights. The results showed that, compared to the full index (which included all selection criteria), omitting either vitality or straightness had a negligible effect, reducing predicted profit gain per hectare by less than one per cent. Height or diameter each had a greater effect, with a loss of predicted profit gain per hectare of up to 6%. Excluding pilodyn penetration from the selection index caused the largest reduction in predicted profit gain per hectare, amounting to over 10%. However, when both height and diameter were removed the predicted profit gain per hectare dropped to one-third of that based on the full index. Finally, ranking and genetic selection for the developed breeding objective was insensitive to changes in the discount rate.
  • Berlin, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail: mats.berlin@skogsforsk.se (email)
  • Lönnstedt, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail:
  • Jansson, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail:
  • Danell, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail:
  • Ericsson, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail:
article id 154, category Research article
Henrik R. Hallingbäck, Gunnar Jansson, Björn Hannrup, Anders Fries. (2010). Which annual rings to assess grain angles in breeding of Scots pine for improved shape stability of sawn timber? Silva Fennica vol. 44 no. 2 article id 154. https://doi.org/10.14214/sf.154
The shape stability properties of sawn timber could be improved by breeding or grading Scots pine (Pinus sylvestris L.) for reduced grain angles. Currently, only grain angle assessments performed in single annual rings can be considered feasible in forest breeding programmes. The relevance of such methods in assessing shape stability traits was evaluated by taking grain angle measurements beneath the bark in a 36-year-old Scots pine progeny trial. Several grain angle measurements from stem discs were also taken from a sample of 162 trees. Phenotypic correlations were estimated between grain angle and the bow, crook and twist developed in 316 sawn and dried boards. All single annual ring assessments, including measurements taken directly under the bark, were significantly correlated with twist. The highest correlations (0.60–0.70) were observed in annual rings numbered 8–20 and at distances of 30–70 mm from the pith, indicating those parts of logs where grain angles have the largest impact on twist. These results suggests, that grain angles measured beneath the bark are relevant to the twist of sawn small timber, and that any single annual ring could be chosen for the assessment, provided that the tree diameter is within the 60–140 mm range. No appreciable correlations were observed between grain angles and either crook or bow.
  • Hallingbäck, Dept of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden ORCID ID:E-mail: henrik.hallingback@vbsg.slu.se (email)
  • Jansson, The Forestry Research Institute of Sweden, Uppsala, Sweden ORCID ID:E-mail:
  • Hannrup, The Forestry Research Institute of Sweden, Uppsala, Sweden ORCID ID:E-mail:
  • Fries, Dept of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden ORCID ID:E-mail:
article id 172, category Research article
Guntis Brumelis, Maris Strazds, Zanna Eglava. (2009). Stand structure and spatial pattern of regeneration of Pinus sylvestris in a natural treed mire in Latvia. Silva Fennica vol. 43 no. 5 article id 172. https://doi.org/10.14214/sf.172
We examined the regeneration patterns of Pinus sylvestris L. in a natural treed mire in the hemiboreal zone in Latvia. Data on tree stem age and size was collected in 207 fine-scale plots (10 m2) and 4 medium-scale plots (400 m2). Size structure of living and dead trees was also estimated on transects 180-m and 250-m length and 10-m width. In addition, the vegetation was described in 1-m2 plots to determine preferred microsites for P. sylvestris establishment. Pinus sylvestris showed continuous regeneration by an inverse J-shaped age and size structure. Pulses of mortality induced by fire were also evident. Regeneration of P. sylvestris was mostly on Sphagnum magellanicam Brid. hummocks free of competition from Ledum palustre L. and graminoids, which were found in small interspersed patches throughout the mire. The spatial pattern of tree cohorts differed, probably due to changing moisture conditions altering seedbed conditions and by fire-induced mortality in specific areas. Recent rapid invasion by Betula pubescens Ehrh. and Picea abies (L.) Karst. in a post-fire period since 1971 is probably associated with drier conditions.
  • Brumelis, Faculty of Biology, University of Latvia, Kronvalda bulv. 4, Riga LV1586, Latvia ORCID ID:E-mail: guntis.brumelis@lu.lv (email)
  • Strazds, Faculty of Biology, University of Latvia, Kronvalda bulv. 4, Riga LV1586, Latvia ORCID ID:E-mail:
  • Eglava, Faculty of Biology, University of Latvia, Kronvalda bulv. 4, Riga LV1586, Latvia ORCID ID:E-mail:
article id 168, category Research article
Saila Varis, Anne Pakkanen, Aina Galofré, Pertti Pulkkinen. (2009). The extent of south-north pollen transfer in Finnish Scots pine. Silva Fennica vol. 43 no. 5 article id 168. https://doi.org/10.14214/sf.168
In order to evaluate the possibility of long distance gene flow in Scots pine (Pinus sylvestris L.), we measured the amount and germinability of airborne pollen and flowering phenology in central, northern, and northernmost Finland during 1997–2000. Totally 2.3% of the detected germinable pollen grains were in the air prior to local pollen shedding. The mean number of germinable pollen grains m–3 air per day was lower prior to local pollen shedding, but in the year 2000 there were more germinable pollen grains in the air of central study site prior to local pollen shedding. Prior to the onset of pollen shedding, 7.5% of female strobili which we observed were receptive. On average female strobili became receptive three days earlier than local pollen shedding started. During the period of pollen shedding in the central study site, we detected germinable airborne pollen in the northern site in years 1997, 1999 and 2000. At the northermost site, we detected germinable airborne pollen during the pollen-shedding period of the northern site in 2000. Our detection of germinable airborne pollen and synchrony of strobili maturation from south to north suggest that populations of Scots pine in central and northern Finland may provide genetic material to populations in northern and northernmost Finland, respectively.
  • Varis, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: saila.varis@metla.fi (email)
  • Pakkanen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
  • Galofré, Passeig de l’estació 21, 5-1, 43800 Valls, Tarragona, Spain ORCID ID:E-mail:
  • Pulkkinen, Finnish Forest Research Institute, Haapastensyrjä Breeding Station, Karkkilantie 247, FI-12600 Läyliäinen, Finland ORCID ID:E-mail:
article id 197, category Research article
Veli-Pekka Ikonen, Seppo Kellomäki, Heli Peltola. (2009). Sawn timber properties of Scots pine as affected by initial stand density, thinning and pruning: a simulation based approach. Silva Fennica vol. 43 no. 3 article id 197. https://doi.org/10.14214/sf.197
The aim of this work was to analyze how different management schedules with varying initial stand density, thinning and artificial pruning of branches affect the quality, quantity and value of sawing yield in Scots pine (Pinus sylvestris L.). For this purpose, an integrated model system was employed and further developed to simulate: i) the three dimensional structure of the crown and stem of an average tree grown in a stand related to the changes in the within-stand light conditions as caused by the stand management, and ii) the sawing of logs into pieces and their quality grading based on the size and number of living and dead knots on the surfaces of sawn pieces. To maximize the quality of sawn timber, relatively dense stand is desired in the early phase of the rotation to reduce, especially in the lower part of stem, the growth of branches, and to increase the rate of dying and pruning-off of branches. In the later phase, a relatively sparse stand is desired to increase the self-pruning of branches and the occlusion of knots. However, in any case, artificial pruning is needed to maximize the knot-free zone of the stem. Also the value optimization of individual sawn pieces affects the quality and value of sawn timber. Because, only average tree was simulated, the differences between scenarios for stem volume were small. In the future, further model development is needed to analyze the development of crown and stem properties of trees with different status in a stand.
  • Ikonen, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: veli-pekka.ikonen@joensuu.fi (email)
  • Kellomäki, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Peltola, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
article id 217, category Research article
Ville Kankaanhuhta, Timo Saksa, Heikki Smolander. (2009). Variation in the results of Norway spruce planting and Scots pine direct seeding in privately-owned forests in southern Finland. Silva Fennica vol. 43 no. 1 article id 217. https://doi.org/10.14214/sf.217
This study describes the variation in the planting results for 3-year-old Norway spruce (Picea abies (L.) Karst.) and 4-year-old Scots pine (Pinus sylvestris L.) using direct seeding in privately-owned regeneration areas in southern Finland. The study material consists of operative forest regeneration quality management inventory areas from the years 2000–2006. The effect of both the regional and the administrative levels as well as ecological factors was modelled on the basis of the hierarchy structure forestry centre, Forest Owners’ Association (= FOA), forestry professional, regeneration area and sample plot. The major part of the variation occurred at the sample plot and regeneration area level. Particular attention was paid to observation of the clustered spatial distribution of Scots pine seedlings. The FOA and forestry professional levels explained 5% of the variation in Norway spruce planting and 11% of the variation in Scots pine direct seeding. Applied forest regeneration operations, site and soil characteristics were included in the fixed effects. In the planting of Norway spruce the most important factor explaining the regeneration result was soil preparation. Mounding produced better results than patching and disc trenching. The site and soil characteristics were other important factors in the operations. The selection of direct seeding of Scots pine on too fertile, fine textured or moist sites yielded poor results.
  • Kankaanhuhta, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: ville.kankaanhuhta@metla.fi (email)
  • Saksa, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Smolander, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
article id 235, category Research article
Ari Nikula, Ville Hallikainen, Risto Jalkanen, Mikko Hyppönen, Kari Mäkitalo. (2008). Modelling the factors predisposing Scots pine to moose damage in artificially regenerated sapling stands in Finnish Lapland. Silva Fennica vol. 42 no. 4 article id 235. https://doi.org/10.14214/sf.235
Moose (Alces alces) damage in forest plantations have been at a high level in Finland in recent decades. Nowadays, moose is the most severe pest in Scots pine plantations also in Finnish Lapland. So far, despite the high level of damage and different bio-geographical conditions in Northern Finland, most of the moose-damage research has been carried out in Southern Finland. A number of research have also been performed to analyse factors affecting browsing but predictive models are rare. Data from 123 randomly selected and artificially regenerated pine plantations in Northern Finland were used in modelling the risk of moose browsing. The stands had been regenerated during 1984–1995. A total of 508 sample plots (range 2–8 plots per stand) were measured. Hierarchical logistic regression models with a random factor were constructed to predict the probability of leader-shoot browsing of pine on a plot. The number of planted pines and deciduous trees overtopping the pines were the most important predictors increasing the browsing probability. The results support earlier findings that deciduous trees overtopping or reaching the height of the pines should be cleaned from the immediate vicinity of the pines. Seedlings with a height ranging from 75 to 299 centimetres were more susceptible to browsing. Heavy soil scarification, such as ploughing or mounding, increased the browsing probability compared with lighter scarification methods. Soil type did not affect the browsing probability, but paludification decreased it. The within-stand variation in deciduous trees density and height should be taken into account in future moose browsing risk assessments. In Lapland, high moose damage risk areas are characterized by a low elevation and higher temperature sum.
  • Nikula, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: ari.nikula@metla.fi (email)
  • Hallikainen, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
  • Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
  • Hyppönen, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
  • Mäkitalo, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
article id 252, category Research article
Tuomo Kalliokoski, Pekka Nygren, Risto Sievänen. (2008). Coarse root architecture of three boreal tree species growing in mixed stands. Silva Fennica vol. 42 no. 2 article id 252. https://doi.org/10.14214/sf.252
Root system architecture determines many of the vital functions of a tree, e.g. stability of anchorage and resource uptake. The shoot:root ratio is determined through the allocation of resources. Studies on below-ground architectural elements in boreal mixed forests are relatively scarce despite the fact that knowledge on below-ground interactions and allocation changes in relation to stand developmental stage and soil fertility is needed both in ecological and silvicultural research. In this study, sixty tree root systems of three different tree species, Betula pendula, Picea abies and Pinus sylvestris, were excavated in five mixed forest stands in order to quantify differences between the species and sites in terms of rooting behaviour. Root architecture differed greatly between the species, implying different solutions for the functions of root systems. Half of the P. sylvestris had developed a taproot as a response to anchorage needs, while P. abies correspondingly had pronounced secondary growth of proximal roots. Betula pendula had the most extensive root system, illustrating the greater demand of deciduous trees for water. Betula pendula was also the most sensitive to soil fertility: it favoured exploration on the poorest site, as illustrated by the high total root length, whereas on the most fertile site its strategy was to efficiently exploit soil resources through increased branching intensity. The results obtained in this study provide basic knowledge on the architectural characteristics of boreal tree root systems for use by forestry professionals and modellers.
  • Kalliokoski, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: tuomo.kalliokoski@metla.fi (email)
  • Nygren, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Sievänen, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
article id 274, category Research article
Timo Saksa, Jari Miina. (2007). Cleaning methods in planted Scots pine stands in southern Finland: 4-year results on survival, growth and whipping damage of pines. Silva Fennica vol. 41 no. 4 article id 274. https://doi.org/10.14214/sf.274
The effects of four cleaning treatments on the survival, growth of, and whipping damage to Scots pine (Pinus sylvestris L.) main stems were studied in young planted pine stands in southern Finland. Treatments were: no cleaning, point-cleaning of broadleaves (mainly birch, Betula pendula Roth and B. pubescens Ehrh.) within a radius of 1 m from the pine, topping of competing broadleaves, and total cleaning of broadleaves. A randomised complete block design with three replicates was established in five sapling stands: the mean height of the pines was 1.5 m in the three younger stands (6 or 7 years old), and 3 m in the two older stands (9 years old). Measurements taken four growing seasons later showed that in the younger stands, all cleaning treatments significantly (P < 0.05) decreased the mortality and increased the diameter increment of the pines. The height increment of the pines on point-cleaned and topped plots was significantly greater than on totally cleaned plots. In the older stands, the effects of cleaning treatments on the mortality and increment of pines were non-significant. In the younger and older stands, point-cleaning and total cleaning significantly reduced the whipping damage to pines, whereas the topping of competing broadleaves did not. The preliminary results support the use of point-cleaning in planted Scots pine stands when the mean height of the pines is about 1.5 m.
  • Saksa, Finnish Forest Research Institute, Suonenjoki Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: timo.saksa@metla.fi (email)
  • Miina, Finnish Forest Research Institute, Joensuu Unit, P.O.Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
article id 300, category Research article
Jouni Siipilehto, Sakari Sarkkola, Lauri Mehtätalo. (2007). Comparing regression estimation techniques when predicting diameter distributions of Scots pine on drained peatlands. Silva Fennica vol. 41 no. 2 article id 300. https://doi.org/10.14214/sf.300
We compared different statistical methods for fitting linear regression models to a longitudinal data of breast height diameter (dbh) distributions of Scots pine dominated stands on drained peatlands. The parameter prediction methods for two parameters of Johnson’s SB distribution, fitted to basal-area dbh distributions, were: 1) a linear model estimated by ordinary least squares (OLS), 2) a multivariate linear model estimated using the seemingly unrelated regression approach (SUR), 3) a linear mixed-effects model with random intercept (MIX), and 4) a multivariate mixed-effects model (MSUR). The aim was to clarify the effect of taking into account the hierarchy of the data, as well as simultaneous estimation of the correlated dependent variables on the model fit and predictions. Instead of the reliability of the predicted parameters, we focused on the reliability of the models in predicting stand conditions. Predicted distributions were validated in terms of bias, RMSE, and error deviation in the generated quantities of the growing stock. The study material consisted of 112 successively measured stands from 12 experimental areas covering the whole of Finland (total of 608 observations). Two independent test data sets were used for model validation. All the advanced regression techniques were superior to OLS, when exactly the same independent stand variables were included. SUR and MSUR were ranked the overall best and second best, respectively. Their ranking was the same in the modeling data, whereas MSUR was superior in the peatland test data and SUR in the mineral soil test data. The ranking of the models was logical, but may not be widely generalized. The SUR and MSUR models were considered to be relevant tools for practical forest management planning purposes over a variety of site types and stand structures.
  • Siipilehto, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: jouni.siipilehto@metla.fi (email)
  • Sarkkola, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
  • Mehtätalo, University of Joensuu, Faculty of Forestry, P.O. Box 111, 80101 Joensuu, Finland ORCID ID:E-mail:
article id 304, category Research article
Joanna Kosinska, Andrzej Lewandowski, Wladyslaw Chalupka. (2007). Genetic variability of Scots pine maternal populations and their progenies. Silva Fennica vol. 41 no. 1 article id 304. https://doi.org/10.14214/sf.304
The genetic variability of Scots pine was investigated in six populations from Poland representing two maternal populations and their natural and artificial progenies. Thirteen enzyme systems controlled by 25 allozyme loci were analyzed using starch gel electrophoresis. Progeny populations maintained a high and similar level of genetic variation to that observed in the maternal populations. As expected, much closer genetic relationships were observed between maternal populations and their respective progeny than between the two maternal populations themselves. Progeny populations had the same major alleles, but differed in the number of rare alleles. Therefore, probably not all rare alleles were transferred from the maternal stands to the progenies. In addition, new rare alleles appeared in the progeny populations, possibly as a result of external pollen flow into the maternal populations.
  • Kosinska, Department of Human Medical Genetics, Medical University of Warsaw, Oczki 1, 02-007 Warsaw, Poland ORCID ID:E-mail:
  • Lewandowski, Polish Academy of Sciences, Institute of Dendrology, 62-035 Kórnik, Poland ORCID ID:E-mail:
  • Chalupka, Polish Academy of Sciences, Institute of Dendrology, 62-035 Kórnik, Poland ORCID ID:E-mail:
article id 320, category Research article
Saija Huuskonen, Jari Hynynen. (2006). Timing and intensity of precommercial thinning and their effects on the first commercial thinning in Scots pine stands. Silva Fennica vol. 40 no. 4 article id 320. https://doi.org/10.14214/sf.320
The effects of the timing and intensity of precommercial thinning on the stand diameter development and wood production in Scots pine stands was addressed. A model was developed in order to assess the thinning response of the stand diameter development. The effect of precommercial and first commercial thinning on the stand volume and the thinning removal at first commercial thinning were also modelled. The models were developed to be applicable for forest management planning purposes. The results are based on Scots pine (Pinus sylvestris L.) trials (13 experiments and 169 plots) located in Southern and Central Finland. Precommercial thinning considerably enhanced the diameter development. Precommercial thinning (at Hdom 3 m to 2000 trees per hectare) increased the mean diameter by 15% at the first commercial thinning stage (Hdom 14 m) compared to the unthinned stand (3000 trees ha–1). Early and intensive precommercial thinning resulted in the strongest response in diameter development. Wide spacing also enhanced the diameter increment. In naturally regenerated stands the diameter development was ca 13% slower than that in seeded stands. The total volume at the time of first commercial thinning was affected by the timing of thinning and the stand structure. The volume of merchantable thinning removal depended on the timing and intensity of precommercial and first commercial thinnings. Delaying the first commercial thinning from 12 meters (Hdom) to 16 meters increased the volume of thinning removal by ca.70%. The early and light precommercial thinning (Hdom 3 m, to density of 3000 trees per hectare) increased the thinning removal by 40% compared to the late and intensive precommercial thinning (at 7 meters to the density of 2000 trees per hectare).
  • Huuskonen, University of Helsinki, Dept. of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Hynynen, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
article id 331, category Research article
Jouni Siipilehto. (2006). Height distributions of Scots pine sapling stands affected by retained tree and edge stand competition. Silva Fennica vol. 40 no. 3 article id 331. https://doi.org/10.14214/sf.331
The paper focused on the height structure of Scots pine saplings affected by (1) retained solitary pine trees or (2) a pine-dominated edge stand. The study material in (1) and (2) consisted of ten separate regeneration areas in southern Finland. In (1) 2-m radius study plots were located at 1, 3, 6 and 10 m distances from 10 systematically selected, solitary retained trees in each stand. In (2) the study plots were systematically located within 20 m from the edge stand. Competition of the individual trees was modelled using ecological field theory. The 24th and 93rd sample percentiles were used for estimating the height distribution using the two-parameter Weibull function. The models incorporated the effect of varying advanced tree competition on the predicted percentiles. Competition free dominant height was used as a driving variable for the developmental phase. Competition resulted in retarded height development within a radius of about 6 m from the retained tree, while it extended up to roughly half of the dominant height of the edge stand. The height distribution without external competition was relatively symmetrical, but increasing competition resulted in a more peaked and skewed distribution. Slight differences were found between northern sunny and southern shaded stand edges, while the least retarded height occurred at the north-western edge receiving morning sunlight. Kolmogorov-Smirnov goodness-of-fit tests showed acceptable and equal fit for both data sets; 2% and 8% of the distributions did not pass the test at the alpha 0.1 level when the Weibull distribution was estimated with the observed or predicted percentiles, respectively.
  • Siipilehto, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: jouni.siipilehto@metla.fi (email)
article id 337, category Research article
Hannu Salminen, Risto Jalkanen. (2006). Modelling variation of needle density of Scots pine at high latitudes. Silva Fennica vol. 40 no. 2 article id 337. https://doi.org/10.14214/sf.337
The relationship between apical extension and needle density and the effect of temperature and precipitation on needle density was modelled using data gathered from forty-nine felled sample trees in five stands of Scots pine (Pinus sylvestris L.) located along a latitudinal transect from the Arctic Circle up to the northern timberline. The lengths were measured and needle densities assessed from all annual shoots located above 1.3 metres using the Needle Trace Method (NTM), resulting, on average, in 39-year-long chronologies. The mean overall needle density was 7.8 short shoots per shoot centimetre. Needle-density variation in the measured data was mostly due to within-tree differences. Of the total variance, within-tree variation yielded 46%, between-tree 21%, and between-year 27%. The dependence of needle density on annual height growth was studied by fitting a multilevel model with random stand-, tree- and year-intercepts, the independent variables being tree age and height growth. There was a very strong negative correlation between height growth and needle density, and the proportion of between-year variance explained solely by height growth and age was 50%. The stand-wise residual variations and their correlations with the temperature and precipitation time series were further analysed with cross-correlation analysis in order to screen for additional independent variables. The only possible additional independent variable found was the precipitation of April–May (precipitation of May in the two northernmost stands). When it was added to the multi-level model, the proportion of explained between-year needle-density variance was 55%, but the overall fit of the model improved only slightly. The effect of late winter and early spring precipitation indicates the role of snow coverage and snowmelt on the growing conditions in the three southernmost stands. In general, stand-level needle-density variation is mostly due to changes in height growth.
  • Salminen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: hannu.salminen@metla.fi (email)
  • Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
article id 349, category Research article
Temel Sariyildiz, J. M. Anderson. (2006). Intra-specific variation in cell wall constituents of needle age classes of Pinus sylvestris in relation to soil fertility status in Southwest England. Silva Fennica vol. 40 no. 1 article id 349. https://doi.org/10.14214/sf.349
First, second and third year needles were collected from the same branches of young Scots pine trees growing on soils of two different status (high and low fertility sites) that varied in mineral nutrient concentrations and N mineralisation potential. All needle age classes were analysed for total carbon, acid detergent fibre (ADF), lignin, cellulose, phenylpropanoid derivatives (PPD) of lignin, sugar constituents of non-crystalline, hydrated cellulose and hemicellulose, and nutrient concentrations (N, P, K, Ca, Mg and Mn). Significant intra-specific variation in the litter quality variables in relation to soils of high and low fertility was found in the second and third year needles, whereas there were no differences in the other cell wall constituents and mineral elements of the first year needles. The second and third year needles from the low fertility soil contained higher concentrations of ADF, lignin, cellulose, sugar constituents of non-crystalline, hydrated cellulose and hemicellulose, and phenylpropanoid derivatives (PPD) of lignin, but lower concentrations of N, P and Mg than the same needles from the high fertility and fertilised soils. The results in the present study indicate that under different soil fertilities, needle age classes show significant variations in the cell wall constituents and mineral elements, and suggest that this can result in significant variation in litter quality and decomposition rates.
  • Sariyildiz, Kars Kafkas Üniversitesi, Artvin Orman Fakültesi, 08000 Artvin, Turkey ORCID ID:E-mail: t_sariyildiz@yahoo.com (email)
  • Anderson, Department of Biological Sciences, Hatherly Laboratories, University of Exeter, Exeter EX4 4PS, UK ORCID ID:E-mail:
article id 362, category Research article
Hannu Salminen, Risto Jalkanen. (2005). Modelling the effect of temperature on height increment of Scots pine at high latitudes. Silva Fennica vol. 39 no. 4 article id 362. https://doi.org/10.14214/sf.362
The effect of temperature and precipitation on the height increment of Pinus sylvestris (L.) was modelled using data gathered from a total of 49 felled sample trees from five stands of Scots pine located along a latitudinal transect from the Arctic Circle up to the northern timberline in Finland. A multilevel mixed effects model and cross-correlation analysis of prewhitened time series was used to analyse the dependence between height increment and monthly meteorological observations. The effect of the mean July temperature of the previous year on height increment proved to be very strong at high latitudes (r > 0.7). The mean November temperature of the year before the previous affected statistically significantly on height increment in the three northernmost stands. There was no correlation between height increment and precipitation in any of the sites. The final height increment model based on all stands included tree age, long-term mean temperature sum of site, and the mean July temperature of the previous year as independent variables. According to the model, one degree’s change in July temperature results on average in 1.8 cm change in the next year’s height increment. There was a modest but significant polynomial age-effect. The proportion of explained variance (at the year level) was 74%. The July temperature dependence on height increment was shown to be very strong, suggesting a high value of height increment in climate modelling at the tree line.
  • Salminen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: hannu.salminen@metla.fi (email)
  • Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
article id 393, category Research article
Seppo Rouvinen, Anne Rautiainen, Jari Kouki. (2005). A relation between historical forest use and current dead woody material in a boreal protected old-growth forest in Finland. Silva Fennica vol. 39 no. 1 article id 393. https://doi.org/10.14214/sf.393
Assessing the human impact on the naturalness and vegetation characteristics of protected areas is one of the key issues when designing forest conservation networks in Fennoscandia. We studied the small-scale, detailed relationship between forest utilization history and the current availability of dead woody material in a protected old-growth forest area in North Karelia, eastern Finland. From the study area of 32.4 ha, all the stumps (diameter ≥ 5 cm and height < 1.3 m, classified as natural, man-made and of undetermined origin) were measured using 25 x 25 m sub-plots. Standing and fallen dead trees (dbh ≥ 5 cm) were measured on 50 x 50 m plots in an area of 7.8 ha. The average number of stumps was 130 per ha, and over half of the stumps were classified as man-made. However, the historical documents since the 1910s showed no logging in the area: some of the largest man-made stumps probably originated from an earlier time, but most of those stumps were made considerably later. The variation in the total number of stumps (per ha) was great (range 0–560/ha, 0–16 m2/ha), with no clear clustering in space. However, clustering of man-made stumps was detected. The average volume of pooled standing and fallen trees was 84 m3/ha, with a range of 37–146 m3/ha. The other noticeable man-made disturbance besides logging was notching of aspens, which has a scatteredly significant influence on the amount of dead trees. In conclusion, the protected old-growth forest was not as a whole in a natural state but showed different degrees of human impact from virtually untouched patches to quite heavily managed patches. The results suggest that the number of man-made stumps may be a relatively quick and easy method of assessing the naturalness of woody biomass structure in the Fennoscandian boreal forests.
  • Rouvinen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: seppo.rouvinen@joensuu.fi (email)
  • Rautiainen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Kouki, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
article id 408, category Research article
Sakari Sarkkola, Hannu Hökkä, Timo Penttilä. (2004). Natural development of stand structure in peatland Scots pine following drainage: results based on long-term monitoring of permanent sample plots. Silva Fennica vol. 38 no. 4 article id 408. https://doi.org/10.14214/sf.408
We studied the dynamics of stand structure on drained peatland sites in Scots pine dominated stands untreated with thinnings. The data consisted of consecutive stand measurements in 10 permanent sample plots where the monitoring periods varied from 29 to 66 years. We assumed that the stand’s structural development was driven by the natural processes of regeneration, growth, and mortality, all related to inter-tree competition within the stand. The DBH distributions of live and dead trees at different times of post-drainage stand development – smoothed by Weibull function – were analysed to characterise the change in stand structure. The initial uneven-sized structure of the natural, widely-spaced stands became more uneven during the first decades following drainage due to enhanced regeneration. Later, as stand density and mean tree size continuously increased, the DBH distributions approached bell-shaped distributions. Accordingly, the suppressed trees showed their highest mortality rate during the first decades, but the peak of the mortality distribution shifted to larger trees along stand succession. The change in structure was faster in southern Finland than in northern Finland. We assumed the changes in stand dynamics reflected increased inter-tree competition, initiated by enhanced site productivity and increased stand stocking resulting from the ditching operation.
  • Sarkkola, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: sakari.sarkkola@helsinki.fi (email)
  • Hökkä, Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Penttilä, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
article id 407, category Research article
Soili Kojola, Timo Penttilä, Raija Laiho. (2004). Impacts of different thinning regimes on the yield of uneven-structured Scots pine stands on drained peatland. Silva Fennica vol. 38 no. 4 article id 407. https://doi.org/10.14214/sf.407
Drained peatlands in northern Europe comprise more than 10 million ha of forestland and thus constitute a considerable production potential in forestry. Much of this area consists of stands dominated by Scots pine and close to maturity regarding commercial thinning. The trees within these stands typically vary in terms of age, size, and growth rate. The impacts of silvicultural cuttings on these uneven-structured stands are inadequately known. We simulated the impacts of a control regime with no thinnings, and three different thinning regimes, involving different thinning intensities, on the development of fifteen pine-dominated stands in Finland. The simulations started from the first thinnings and were continued until regeneration maturity. The predicted total yields ranged from 244 to 595 m3 ha–1, depending on site and thinning regime. The highest total yields were observed for the control regime in which 18–38% of the yield was, however, predicted to self-thin by the end of the simulation. Thus, the differences in the yields of merchantable wood were fairly small among the compared regimes. However, the regimes involving thinnings generally needed less time than the control regime to reach regeneration maturity. The mean annual increment of total stem volume was at its highest in the control regime. The highest mean annual increment of merchantable wood was obtained in the regime involving two moderate thinnings, but excluding the most low-productive sites where thinnings did not increase the yield of merchantable wood.
  • Kojola, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail: soili.kojola@metla.fi (email)
  • Penttilä, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail:
  • Laiho, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:
article id 424, category Research article
Mats Warensjö, Göran Rune. (2004). Stem straightness and compression wood in a 22-year-old stand of container-grown Scots pine trees. Silva Fennica vol. 38 no. 2 article id 424. https://doi.org/10.14214/sf.424
The distribution of compression wood in relation to eccentric growth and development of stem straightness was studied in a 22-year-old Scots pine (Pinus sylvestris L.) stand in central Sweden that was established with container-grown seedlings. Stem straightness was measured on the same 440 trees in 1986 and 1997. The number of stems with straight base sections increased from 60% in 1986 to 89% in 1997. Measurements of 72 sample trees in 2001 showed that 96% of the trees had developed straight stem bases. External geometry data of the logs was obtained with a Rema 3D log scanner. A sub-sample of 16 trees was randomly selected for analysis of compression wood distribution and eccentricity measurements. From each tree, 11 discs were cut at every 60 cm along the stem. All discs, except one, contained compression wood. Compression wood and pith eccentricity was most pronounced near the stem base but not significantly correlated to basal sweep. Severe compression wood content was correlated to pith eccentricity and bow height. In general, correlations were better for the basal sections of the logs. Even though most trees were straight, they contained large amounts of compression wood. It is evident that eccentric growth and compression wood formation play major roles in the development of stem straightness. In several stems, a spiral compression wood distribution pattern was found. Reasons for this are discussed.
  • Warensjö, Department of Forest Products and Markets, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden ORCID ID:E-mail: mats.warensjo@spm.slu.se (email)
  • Rune, Department of Forestry and Wood Technology, Dalarna University, SE-776 98 Garpenberg, Sweden ORCID ID:E-mail:
article id 436, category Research article
Martti Varmola, Hannu Salminen, Mauri Timonen. (2004). Thinning response and growth trends of seeded Scots pine stands at the arctic timberline. Silva Fennica vol. 38 no. 1 article id 436. https://doi.org/10.14214/sf.436
Growth patterns and reactions of Scots pine (Pinus sylvestris L.) to thinning in extremely harsh climatic conditions were studied in two seeded Scots pine stands located on the arctic timberline. Coniferous trees usually do not form closed stands at the timberline, but occur only in scattered tree groups. The trial was established in two stands in 1985–1986 when the trees were at an age of 47 and 56 years and an average dominant height of 6.0–6.9 m. The trial was remeasured in 1998. The thinning treatments reduced the stem number for five different levels; final density of 300, 550, 800, 1050, and 1300 stems ha–1 and unthinned. The experiment had a randomised block design with four replications in each stand. The increased growing space provided by thinning accelerated diameter growth after a delay of 2–3 years. The differences between the radial growth of the thinning treatments were very clear during the whole 13- to 14-year observation period. Annual increment of the mean diameter was regularly the higher, the larger the spacing. Dominant diameter was less influenced by treatments. There were no significant differences in dominant height between any of the treatments. Both basal area and volume were regularly the greater the higher the stem number was. Even a relatively light thinning had a distinct positive effect on tree growth, i.e. not carrying out thinning resulted in a production loss of merchantable wood. According to the results, seeded stands on the arctic timberline can grow surprisingly well in favourable conditions and reach a dominant height of 12–14 m in 100 years and a mean annual increment of 1.0–1.5 m3 ha–1 y–1 over a rotation period of 130–160 years. Based on increment figures and thinning reactions, a spacing of ca. 1000 stems ha–1 can be recommended.
  • Varmola, The Finnish Forest Research Institute, Rovaniemi Research Station, P.O.Box 16, FIN-96301 Rovaniemi, Finland ORCID ID:E-mail: martti.varmola@metla.fi (email)
  • Salminen, The Finnish Forest Research Institute, Rovaniemi Research Station, P.O.Box 16, FIN-96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Timonen, The Finnish Forest Research Institute, Rovaniemi Research Station, P.O.Box 16, FIN-96301 Rovaniemi, Finland ORCID ID:E-mail:
article id 432, category Research article
Bo Långström, Claes Hellqvist, Jan Cedervind. (2004). Comparison of methods for estimation of needle losses in Scots pine following defoliation by Bupalus piniaria. Silva Fennica vol. 38 no. 1 article id 432. https://doi.org/10.14214/sf.432
In 1996, ca. 7000 hectares of pine forests at Hökensås in SW Sweden were defoliated by the pine looper, Bupalus piniara (L.) (Lepidoptera. Geometridae). Following an aerial damage survey using CIR (colour infra red) photography, and estimation of pupal densities in the soil, ca 4000 ha of the most defoliated pine stands were sprayed in early August 1997 with Bacillus thuringiensis var. kurstaki. The control operation was succeessful but probably redundant, as no further defoliation occurred in unsprayed reference areas. In order to assess defoliation levels in different damage classes for later growth loss studies, 47 circular study plots were laid out in pine stands representing different damage and age classes. The remaining foliage was recorded for each tree using the following classes: 0, 10, 30, 50, 70, 90 and 100%. The defoliation levels in 1996 were estimated by disregarding the 1997 needle age class. Thirteen ca. 40-year-old sample trees representing different damage classes were felled, and the remaining foliage of all branches was estimated by needle age class using the above-mentioned scale. One branch in each of the whorls 1996, 1991, 1986 and 1981 was sampled and its needle dry weight was determined. The sample branch data confirmed the field observations that virtually no additional defoliation took place in 1997. The damage classes estimated from the CIR-pictures only agreed with the field damage estimates at the higher end of the damage scale. In contrast, the field estimate correlated well with plot means derived from tree-wise estimates (R2 = 0.93), and with with the calculated needle biomasses per tree (R2 = 0.90). Thus, the field damage classification was supported by the more detailed defoliation estimates, and hence forms a relevant basis for later growth loss studies.
  • Långström, SLU, Dept. of Entomology, P.O.Box 7044, S-750 07 Uppsala, Sweden. Fax +46 18 672 890 ORCID ID:E-mail: bo.langstrom@entom.slu.se (email)
  • Hellqvist, SLU, Dept. of Entomology, P.O.Box 7044, S-750 07 Uppsala, Sweden. Fax +46 18 672 890 ORCID ID:E-mail:
  • Cedervind, SLU, Dept. of Entomology, P.O.Box 7044, S-750 07 Uppsala, Sweden. Fax +46 18 672 890 ORCID ID:E-mail:
article id 483, category Research article
Staffan Jacobson. (2003). Addition of stabilized wood ashes to Swedish coniferous stands on mineral soils - effects on stem growth and needle nutrient concentrations. Silva Fennica vol. 37 no. 4 article id 483. https://doi.org/10.14214/sf.483
Increasing use of forest fuels for energy production is generating increasing quantities of wood ash. A common understanding is that this ash should be spread in forests to counteract soil acidification and potential future nutrient deficiencies, and thus help sustain long-term forest productivity. A series of seven field experiments was established in Sweden in 1988–1995 to study the stem growth and needle nutrient concentrations of 30–60-year-old Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands on mineral soil after additions of wood ash in different doses or a combination of wood ash and N. The results showed that the most pronounced growth responses occurred when N was added, either alone or in combination with wood ash. The stem growth responses to additions of wood ash without N were small and variable, and not statistically significant at any of the studied experimental sites. However, there were indications that the addition of wood ash may increase stem-wood growth on fertile sites and decrease it on less fertile sites. In the short term, the addition of wood ash tended to increase the needle nutrient concentrations of most analyzed elements, except for N, but this could not be correlated to responses in stem growth.
  • Jacobson, The Forestry Research Institute of Sweden, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail: staffan.jacobson@skogforsk.se (email)
article id 494, category Research article
Antero Varhimo, Soili Kojola, Timo Penttilä, Raija Laiho. (2003). Quality and yield of pulpwood in drained peatland forests: pulpwood properties of Scots pine in stands of first commercial thinnings. Silva Fennica vol. 37 no. 3 article id 494. https://doi.org/10.14214/sf.494
The inherent structural dynamics of drained peatland forests may result in a great variation in various wood and fiber properties. We examined variation in fiber and pulp properties i) among stands, ii) among trees within stands, and iii) within trees in young stands dominated by Scots pine (Pinus sylvestris L.). The stands, selected to cover a maximal range of the potential variation, were all at a stage of development where the first commercial thinnings would be feasible. Differences in the processability of the thinning removals were small. In similar kraft cooking conditions, a 5-unit variation in the kappa number of unbleached pulp was observed among the stands. Stand origin had no effect on pulp bleaching. The wood formed prior to drainage had a higher density, shorter fibers, was slightly slower delignified by cooking, and its yield was slightly lower than that of post-drainage wood. These properties, except for high density, are typical for juvenile wood in general, and at stand level they did not correlate with the proportion of pre-drainage wood. When the variation in fiber and pulp properties was broken down into its components, most of it was derived from tree-level in all the cases. On average, the fiber and pulp properties did not differ from those observed for first-thinning pulpwood from upland sites. Consequently, peatland-grown pulpwood may be mixed with other pulpwood in industrial processes. It would probably be best suited as the raw material for pulps with high bonding requirements, e.g. in the top ply of multi-ply board grades or in some specialty grades.
  • Varhimo, KCL, P.O. Box 70, FIN-02151 Espoo, Finland ORCID ID:E-mail: antero.varhimo@kcl.fi (email)
  • Kojola, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail:
  • Penttilä, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail:
  • Laiho, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: raija.laiho@helsinki.fi
article id 493, category Research article
Göran Rune. (2003). Slits in container wall improve root structure and stem straightness of outplanted Scots pine seedlings. Silva Fennica vol. 37 no. 3 article id 493. https://doi.org/10.14214/sf.493
Root structure and basal sweep were measured on 6-year-old Scots pine (Pinus sylvestris L.) trees at two sites with different soil fertility. Each site was planted with seedlings of identical origin after nursery cultivation in either solidwall container types with vertical ribs or in slitwall container types. Neither container design nor container volume affected tree height or stem diameter on the two sites. The transversal area of lateral roots was larger than the transversal area of bottom roots for the two container types at both sites. The proportion of bottom root transversal area to the total root transversal area was larger in the seedlings growing on the low fertility site than in those growing in the high fertility site for both container types. Seedlings cultivated in slitwall containers had a larger root area in proportion to stem diameter and had less root spiralling compared to the trees cultivated in solidwall containers. At the high fertility site, trees from the slitwall container type had straighter stem bases than seedlings grown in solidwall containers. At the low fertility site, differences in basal sweep formation were small between the container types. Reasons for this are discussed.
  • Rune, Dalarna University, Department of Forestry and Wood Technology, SE-776 98 Garpenberg, Sweden ORCID ID:E-mail: gru@du.se (email)
article id 492, category Research article
Seppo Kaunisto, Tytti Sarjala. (2003). Foliar potassium concentrations of bilberry, bog bilberry and downy birch as indicators of potassium nutrition of Scots pine on a drained peatland. Silva Fennica vol. 37 no. 3 article id 492. https://doi.org/10.14214/sf.492
Leaves of bilberry (V. myrtillus), bog bilberry (V. uliginosum) and downy birch (B. pubescens) were collected five times during a growing season from 18 plots in a drainage area, and needles of Scots pine (Pinus sylvestris L.) once during the following winter from the same plots at Parkano, southern Finland. The aim was to study the potassium nutrition of the test plants and relationships between the foliar potassium concentrations of Scots pine and of the test plants. The estimation of the potassium nutrition of test plants was based on the accumulation of putrescine in foliage. Apart from single observations, elevated putrescine concentrations were found when the potassium concentrations were < 5 mg g–1 in bilberry, < 4 mg g–1 in bog bilberry and < 6 mg g–1 in downy birch, and the highest concentrations below the potassium levels of 3.0–3.5 mg g–1. At the concentrations of 2–3 mg g–1 the accumulation increased pronouncedly in bog bilberry but less in downy birch and only slightly in bilberry. The foliar potassium concentrations in test plants correlated closely with the concentrations in pine needles. The concentrations of all species in August were quite stable at the levels of the severe and slight potassium deficiency of pine (3.5 and 4.5 mg g–1 respectively) indicating that August would be suitable for collecting foliage. The concentrations in bog bilberry were very close to the concentrations in pine at the severe and those in bilberry at the slight deficiency level of pine. All test plants could be used for predicting the potassium nutrition of Scots pine, but additional research is needed for the practical application of the method.
  • Kaunisto, Finnish Forest Research Institute, Parkano Research Station, Kaironiementie 54, FIN-39700 Parkano, Finland ORCID ID:E-mail: seppo.kaunisto@metla.fi (email)
  • Sarjala, Finnish Forest Research Institute, Parkano Research Station, Kaironiementie 54, FIN-39700 Parkano, Finland ORCID ID:E-mail:
article id 504, category Research article
Sylvain Jutras, Hannu Hökkä, Virpi Alenius, Hannu Salminen. (2003). Modeling mortality of individual trees in drained peatland sites in Finland. Silva Fennica vol. 37 no. 2 article id 504. https://doi.org/10.14214/sf.504
Multilevel logistic regression models were constructed to predict the 5-year mortality of Scots pine (Pinus sylvestris L.) and pubescent birch (Betula pubescens Ehrh.) growing in drained peatland stands in northern and central Finland. Data concerning tree mortality were obtained from two successive measurements of the National Forest Inventory-based permanent sample plot data base covering pure and mixed stands of Scots pine and pubescent birch. In the modeling data, Scots pine showed an average observed mortality of 2.73% compared to 2.98% for pubescent birch. In the model construction, stepwise logistic regression and multilevel models methods were applied, the latter making it possible to address the hierarchical data, thus obtaining unbiased estimates for model parameters. For both species, mortality was explained by tree size, competitive position, stand density, species admixture, and site quality. The expected need for ditch network maintenance or re-paludification did not influence mortality. The multilevel models showed the lowest bias in the modeling data. The models were further validated against independent test data and by embedding them in a stand simulator. In 100-year simulations with different initial stand conditions, the models resulted in a 72% and 66% higher total mortality rate for the stem numbers of pine and birch, respectively, compared to previously used mortality models. The developed models are expected to improve the accuracy of stand forecasts in drained peatland sites.
  • Jutras, Département des sciences du bois et de la forêt, Université Laval, Ste-Foy, Québec, G1K 7P4, Canada ORCID ID:E-mail:
  • Hökkä, Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FIN 96301 Rovaniemi, Finland ORCID ID:E-mail: hannu.hokka@metla.fi (email)
  • Alenius, Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FIN 96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Salminen, Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FIN 96301 Rovaniemi, Finland ORCID ID:E-mail:
article id 499, category Research article
Mikhail V. Kozlov, Pekka Niemelä. (2003). Drought is more stressful for northern populations of Scots pine than low summer temperatures. Silva Fennica vol. 37 no. 2 article id 499. https://doi.org/10.14214/sf.499
Needle fluctuating asymmetry, which is a non-specific stress indicator, was used to evaluate responses of Scots pine (Pinus sylvestris L.) to annual climatic variation in the Kola Peninsula, NW Russia, during 1992–1999. Although the 30 trees surveyed for this study demonstrated individualistic responses to the temperature and precipitation of the growth seasons, at the population level we found no effect of temperature and a significant increase in fluctuating asymmetry with a decline in precipitation during the previous August. This finding suggests that the vitality of Scots pine populations at the northern tree limit is controlled by late summer precipitation rather than by temperatures of the growth season.
  • Kozlov, Section of Ecology, University of Turku, 20014 Turku, Finland ORCID ID:E-mail: mikoz@utu.fi (email)
  • Niemelä, Forestry Faculty, University of Joensuu, P.O. Box 111, 80101 Joensuu, Finland ORCID ID:E-mail:
article id 498, category Research article
Slobodan B. Mickovski, A. Roland Ennos. (2003). Anchorage and asymmetry in the root system of Pinus peuce. Silva Fennica vol. 37 no. 2 article id 498. https://doi.org/10.14214/sf.498
The relationship between the anchorage mechanics and root architecture of Pinus peuce was investigated by carrying out winching tests and examining excavated root systems of 20 mature trees. The root system was dominated by 6.1±1.3 lateral roots, more than 70% of the lateral root cross sectional area (CSA) being distributed in the uppermost 10 cm of soil. Anchorage strength was related to the size of the tree and CSA. The overturning moment of trees was proportional to the diameter at breast height (DBH) to the power of 1.6. The trees exhibited significant asymmetry in anchorage rigidity, but although there was clustering of lateral roots in a preferred direction the root asymmetry was not significantly correlated with the asymmetry in anchorage rigidity, suggesting that much of the anchorage is provided by tap and sinker roots, rather than the laterals. However, the major laterals showed dorsoventral eccentricity, the more eccentric ones being those that were distributed closer to the soil surface and which pointed perpendicular to the direction of greatest resistance. This suggests that this is a result of thigmomorphogenetic effects. These results are compared with those for the related P. sylvestris and suggest that the assimilation and anchorage characteristics of root systems are controlled independently of each other.
  • Mickovski, School of Biological Sciences, University of Manchester, 3.614 Stopford Building, Manchester M13 9PT, UK ORCID ID:E-mail:
  • Ennos, School of Biological Sciences, University of Manchester, 3.614 Stopford Building, Manchester M13 9PT, UK ORCID ID:E-mail: roland.ennos@man.ac.uk (email)
article id 524, category Research article
Timo Pukkala, Jari Miina, Marc Palahí. (2002). Thinning response and thinning bias in a young Scots pine stand. Silva Fennica vol. 36 no. 4 article id 524. https://doi.org/10.14214/sf.524
The study analyses the annual post-thinning response and thinning bias of a young Scots pine stand as a function of tree size, competition faced by the tree, and competition that is removed around the tree in the thinning treatment. The thinning response of a tree was defined as the change of tree growth due to a thinning treatment. The thinning bias was defined as the difference between the true growth and model prediction. A distance-dependent (spatial) and a distance-independent (non-spatial) growth model were used in the calculations. The empirical data were measured from a thinning experiment consisting of ten plots, each 40 x 30 m in size, which were thinned to different stand densities. The ten-year post-thinning growth of every remaining tree was measured. The results indicated that the highest thinning response is among medium-sized and co-dominant trees. The thinning response is quite small, and even negative for some trees, for two years after thinning but it becomes clearly positive from the third year onwards. The spatial model underestimated the growth of small trees (which usually face high competition) while the non-spatial model overestimated the growth of trees that are small or face much competition. The spatial model used in this study overemphasized the effect of competition while the non-spatial model underestimated this effect. Both growth models overestimated the growth of trees in heavily thinned places, but this bias disappeared in two years. The negative bias was more pronounced with a spatial growth model because the tendency of the non-spatial model to underestimate the growth of trees facing little competition partly compensated for the negative bias.
  • Pukkala, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland ORCID ID:E-mail: timo.pukkala@joensuu.fi (email)
  • Miina, Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail:
  • Palahí, European Forest Institute, Torikatu 34, FIN-80100 Joensuu, Finland ORCID ID:E-mail:
article id 519, category Research article
Magnus Lindén, Gudmund Vollbrecht. (2002). Sensitivity of Picea abies to butt rot in pure stands and in mixed stands with Pinus sylvestris in southern Sweden. Silva Fennica vol. 36 no. 4 article id 519. https://doi.org/10.14214/sf.519
Repeatedly sampled data from permanent experimental plots in southern Sweden were used to model butt rot development in Norway spruce growing in pure stands and in mixed stands with Scots pine. The data come from 29 sites with pure spruce, altogether 100 plots, and from 15 sites of mixed spruce and pine, altogether 22 plots. A logistic model provided the best fit to the data. The study material revealed that in mixed stands the proportion of spruce trees with butt rot is lower than in pure Norway spruce stands. The difference in the incidence of butt rot cannot be explained by silviculture or windthrow since both factors are accounted for in the study. The most significant effect on butt rot development in Norway spruce by an admixture of Scots pine, was found when the Scots pine admixture was 50%. In order to reduce the incidence of butt rot in Norway spruce, the study material indicate that there is little to be gained by increasing the Scots pine admixture to much more than 50%.
  • Lindén, Southern Swedish Forest Research Centre c/o Asa Experimental Forest, SLU, S-360 30 Lammhult, Sweden ORCID ID:E-mail: magnus.linden@ess.slu.se (email)
  • Vollbrecht, Southern Swedish Forest Research Centre c/o Asa Experimental Forest, SLU, S-360 30 Lammhult, Sweden ORCID ID:E-mail:
article id 529, category Research article
Tuula Aalto, Pertti Hari, Timo Vesala. (2002). Comparison of an optimal stomatal regulation model and a biochemical model in explaining CO2 exchange in field conditions. Silva Fennica vol. 36 no. 3 article id 529. https://doi.org/10.14214/sf.529
Gas exchange of Pinus sylvestris L. was studied in subarctic field conditions. Aspects on optimal control of the gas exchange were examined using approach by Hari et al. (Tree Phys. 2: 169–175, 1986). Biochemical model by Farquhar et al. (Planta 149: 78–90, 1980) was utilized to describe the photosynthetic production rate of needles. The model parameters were determined from field measurements. The results from the optimization approach and biochemical model were compared and their performance was found quite similar in terms of R2 calculated using measured exchange rates (0.89 for optimization model and 0.85 for biochemical model). Minor differences were found in relation to responses to intercellular carbon dioxide concentration and temperature.
  • Aalto, Finnish Meteorological Institute, Air Quality Research, Sahaajankatu 20 E, FIN-00810 Helsinki, Finland ORCID ID:E-mail: tuula.aalto@fmi.fi (email)
  • Hari, University of Helsinki, Dept. of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Vesala, University of Helsinki, Dept. of Physics, P.O. Box 64, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:
article id 539, category Research article
Martti Venäläinen, Seppo Ruotsalainen. (2002). Procedure for managing large-scale progeny test data: a case study of Scots pine in Finland. Silva Fennica vol. 36 no. 2 article id 539. https://doi.org/10.14214/sf.539
Large progeny test networks are typical for conventional forest tree breeding programmes. The individual progeny tests differ with respect to age, composition and ability to screen the breeding values of the parent trees. Several approaches have been introduced to manage the unbalanced and diverse nature of the data generated by progeny tests. This report presents a procedure for ranking breeding material on the basis of ‘messy’ data. Plot means were used as input values and missing plots were estimated from least squares. The differences between test means and variances were standardised by the performance level method. The different precision of the tests was quantified through the reliability coefficient. In order to facilitate the selection of plus trees for different purposes, all the available test results were combined into a single variable that was used for ranking. Three different kinds of ranking variable were calculated and each of them proved to be more useful for the selection of plus trees than an arithmetic or weighted mean. One of them, WMEAN, relied on the reliability and number of the progeny tests, while the others, WCONF0.50 and WCONF0.10, relied on the standard error of the plus tree mean, thus emphasising the precision of the values obtained. The analyses were carried out with SAS® procedures, which require only moderate skills in statistics, programming and data processing technology. The procedure has functioned well throughout an eight-year development phase. Nearly three thousand Scots pine (Pinus sylvestris) plus trees have been ranked for various characters, and the results have been used for roguing the seed orchards, to establish new ones, and to select plus trees for breeding populations.
  • Venäläinen, Finnish Forest Research Institute, Punkaharju Research Station, FIN-58450 Punkaharju, Finland ORCID ID:E-mail: martti.venalainen@metla.fi (email)
  • Ruotsalainen, Finnish Forest Research Institute, Punkaharju Research Station, FIN-58450 Punkaharju, Finland ORCID ID:E-mail:
article id 538, category Research article
Seppo Nevalainen. (2002). The incidence of Gremmeniella abietina in relation to topography in southern Finland. Silva Fennica vol. 36 no. 2 article id 538. https://doi.org/10.14214/sf.538
Field data of the 8th National Forest Inventory (NFI) from southern Finland and digital elevation models (DEMs) were used in this study. Damage due to Gremmeniella abietina increased slightly with an increase in absolute elevation in mineral soils. Severe damage increased almost linearly with an increase in elevation in mineral soil plots. The mean elevation in the tract area (the 7 km x 8 km area surrounding the plot) was more strongly correlated with the disease than the elevation of individual plots. The relative altitude of the plot was important: the disease was most severe in the plots situated lower than the mean elevation of the tract area, especially in the peatland plots. In this group, the damage increased linearly with an increase in absolute elevation. According to detailed DEMs in the most diseased areas, steepness of the slope was negatively correlated with the disease. The aspect of the slope had a weak influence. On mineral soils, the disease was most common in south-facing slopes. The microtopography was not as important for the disease occurrence as the relative elevation of the plot. The disease frequencies were very similarly related to the three most common types of surface features (channels, ridges and planar regions) within the 50-m scale. At the cell size of 100 metres, the disease was more common in channels than in ridges, except in mineral soil plots. Topographic variables only partly explained the regional patterns in the occurrence of this disease. The disease was frequent on upland areas, but, on the other hand, it was also common on lowland areas. The most diseased areas studied in detail differed very much from each other with respect to topography and the disease incidence.
  • Nevalainen, Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail: seppo.nevalainen@metla.fi (email)
article id 537, category Research article
Timo Kurkela. (2002). Crown condition as an indicator of the incidence of root rot caused by Heterobasidion annosum in Scots pine stands. Silva Fennica vol. 36 no. 2 article id 537. https://doi.org/10.14214/sf.537
Trees in three Scots pine stands seriously infected by Heterobasidion annosum were classified according to their crown condition into four classes, from healthy to dead trees. After cutting the stands, the classification was compared with the symptoms of annosum root rot on stump surfaces (pitched area) and with the extension of decay in the roots of excavated stumps. When dead trees were included, the average crown condition on the survey plots correlated with disease incidence. Without dead trees the correlation was not significant. Slightly infected trees could not be distinguished from healthy trees on the basis of crown condition. It was concluded that only the proportion of dead and dying trees in a stand is a reliable indication of the disease incidence for making decisions about the future management.
  • Kurkela, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail: timo.kurkela@metla.fi (email)
article id 557, category Research article
Tuomo Wallenius, Timo Kuuluvainen, Raimo Heikkilä, Tapio Lindholm. (2002). Spatial tree age structure and fire history in two old-growth forests in eastern Fennoscandia. Silva Fennica vol. 36 no. 1 article id 557. https://doi.org/10.14214/sf.557
Two near natural old-growth forests, one dominated by Picea abies and the other by Pinus sylvestris, were studied for their fire history, and spatial patterns of trees and tree ages. The spatial tree age structure and the disturbance history of the forests were examined by drawing age class maps based on mapped and aged trees and by dating fires based on fire scars, and by using spatial analyses at tree scale. The tree age structures of the Picea and Pinus dominated forests were different, mainly due to differences in fire history and sensitivity of the dominant tree species to fire. Fire histories and tree age structures of both sites have probably been affected by human in the ancient past. However, in the Picea dominated site, the fires had been severe, killing most of the trees, whereas in the Pinus dominated site the severity of fires had been more variable, leaving some Pinus and even Picea trees alive. In the Pinus dominated site, the tree age distribution was multimodal, consisting of two Pinus cohorts, which were established after fires and a later Picea regeneration. The Picea dominated site was composed of four patches of different disturbance history. In the oldest patch, the tree age distribution was unimodal, with no distinct cohorts, while a single cohort that regenerated after severe fire disturbances dominated the three other patches. In both sites the overall spatial patterns of living and dead trees were random and the proportion of spatially autocorrelated variance of tree age was low. This means that trees of different age grew more or less mixed in the forest without forming spatially distinct regeneration patches, even in the oldest patch of Picea dominated Liimatanvaara, well over 200 years after a fire. The results show that detail knowledge of disturbance history is essential for understanding the development of tree age structures and their spatial patterns.
  • Wallenius, Department of Ecology and Systematics, University of Helsinki, P.O. Box 65, FIN-00014, Helsinki, Finland ORCID ID:E-mail: tuomo.wallenius@helsinki.fi (email)
  • Kuuluvainen, Department of Forest Ecology, University of Helsinki, P.O. Box 27, FIN-00014, Helsinki, Finland ORCID ID:E-mail:
  • Heikkilä, Research Centre of Friendship Park, Tönölä, FIN-88900 Kuhmo, Finland ORCID ID:E-mail:
  • Lindholm, Finnish Environment Institute, Nature and Land Use Division, P.O. Box 140, FIN-00251 Helsinki, Finland ORCID ID:E-mail:
article id 590, category Research article
Anna Saarsalmi, Eino Mälkönen, Sirpa Piirainen. (2001). Effects of wood ash fertilization on forest soil chemical properties. Silva Fennica vol. 35 no. 3 article id 590. https://doi.org/10.14214/sf.590
The effects of wood ash fertilization on soil chemical properties were studied in three young Scots pine (Pinus sylvestris L.) plantations and a Norway spruce (Picea abies (L.) Karst.) plantation with different site fertility in southern Finland. The dose of 3 t ha–1 of loose wood ash was applied to 4 replicate plots (25 x 25 m) at each experiment. Humus layer and mineral soil samples were taken before the treatment and 7 and 16 years after wood ash application. Results showed that neutralization as well as fertilization effects of wood ash on forest soil were of long duration. An ash-induced pH increase of 0.6–1.0 pH units and exchangeable acidity (EA) decrease of 58–83% were detected in the humus layer 16 years after wood ash application. The decrease in acidity was most pronounced on the Calluna site with initially the lowest pH and highest EA. In the mineral soil the increase in pH was observed later than in the humus layer. After 16 years, the mineral soil pH was increased (0.2–0.3 pH units) on the Vaccinium and Myrtillus sites. A corresponding and in most cases a significant increase in the extractable Ca and Mg concentrations was detected in both the humus layer and in the mineral soil. Wood ash significantly increased the effective cation exchange capacity (CECe) and base saturation (BS) but decreased the concentration of exchangeable Al in both soil layers on all the sites. No response of N availability to wood ash application could be found.
  • Saarsalmi, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail: anna.saarsalmi@metla.fi (email)
  • Mälkönen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail:
  • Piirainen, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail:
article id 617, category Research article
Jouni Siipilehto. (2000). A comparison of two parameter prediction methods for stand structure in Finland. Silva Fennica vol. 34 no. 4 article id 617. https://doi.org/10.14214/sf.617
The objective of this paper was to predict a model for describing stand structure of tree heights (h) and diameters at breast height (dbh). The research material consisted of data collected from 64 stands of Norway spruce (Picea abies Karst.) and 91 stands of Scots pine (Pinus sylvestris L.) located in southern Finland. Both stand types contained birch (Betula pendula Roth and B. pubescent Ehrh.) admixtures. The traditional univariate approach (Model I) of using the dbh distribution (Johnson’s SB) together with a height curve (Näslund’s function) was compared against the bivariate approaches, Johnson’s SBB distribution (Model II) and Model Ie. In Model Ie within-dbh-class h-variation was included by transforming a normally distributed homogenous error of linearized Näslund’s function to concern real heights. Basal-area-weighted distributions were estimated using the maximum likelihood (ML) method. Species-specific prediction models were derived using linear regression analysis. The models were compared with Kolmogorov-Smirnov tests for marginal distributions, accuracy of stand variables and the dbh-h relationship of individual trees. The differences in the stand characteristics between the models were marginal. Model I gave a slightly better fit for spruce, but Model II was better for pine stands. The univariate Model I resulted in clearly too narrow marginal h-distribution for pine. It is recommended applying of a constrained ML method for reasonable dbh-h relationship instead of using a pure ML method when fitting the SBB model.
  • Siipilehto, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail: jouni.siipilehto@metla.fi (email)
article id 641, category Research article
Juha Kaitera. (2000). Analysis of Cronartium flaccidum lesion development on pole-stage Scots pines. Silva Fennica vol. 34 no. 1 article id 641. https://doi.org/10.14214/sf.641
Historical and current lesion development and sporulation of Cronartium flaccidum was investigated in a stand of artificially seeded pole-stage Pinus sylvestris in northern Finland. An average of 6.5 lesions developed per infected tree, most of them occurring on a minority (25%) of the trees. During the monitoring period of five years, fresh aecia appeared mainly in 7–10-year-old shoots, the age of the shoots bearing aecia varying between 3–20 years. Aecia appeared for the first time most frequently in 5–10-year-old shoots. Infection waves occurred, whereas lesions were formed most frequently in shoots formed in various years through the 1980s. After the lesions started to sporulate, sporulation in most lesions that finished sporulating during the monitoring period lasted for 1–2 years. The aecia in between 47% and 59% of the infected shoots developed annually over a longer length in proximal direction than in distal direction next to the previous year’s infection. The aecia-bearing distal part of the shoot was longer in between 19% and 37% of the shoots.
  • Kaitera, Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FIN-96301 Rovaniemi, Finland ORCID ID:E-mail: juha.kaitera@metla.fi (email)
article id 647, category Research article
Tapio Linkosalo. (1999). Regularities and patterns in the spring phenology of some boreal trees. Silva Fennica vol. 33 no. 4 article id 647. https://doi.org/10.14214/sf.647
Phenological time series of flowering and bud burst of Populus tremula (L.) and Betula sp., and the flowering of Pinus sylvestris (L.), Alnus glutinosa (L.) and Alnus incana (L.) were constructed from data collected in Finland during the period 1896–1955. The resulting combined time series were examined with two aims in mind: first, to determine the phenological regularities between different species and, second, to detect patterns of spring advancement over a geographically large area. The results indicate that the geographical pattern of spring advancement is rather uniform from year to year, and between different species. Furthermore, the mechanisms regulating the timing of phenological events in different species seem to function in a similar way, suggesting an unanimous optimal response to climatic conditions.
  • Linkosalo, University of Helsinki, Department of Forest Ecology, Unioninkatu 40 B, P.O. Box 24, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: tapio.linkosalo@helsinki.fi (email)
article id 662, category Research article
Lars Björklund. (1999). Identifying heartwood-rich stands or stems of Pinus sylvestris by using inventory data. Silva Fennica vol. 33 no. 2 article id 662. https://doi.org/10.14214/sf.662
Variations in heartwood percentage, heartwood radius and sapwood width, within and between stands of Scots pine (Pinus sylvestris L.), were analysed using a database of 198 CT-scanned (computer tomography) stems from 33 research plots (stands) throughout Sweden. Heartwood percentage varied greatly both between individual trees and between stands, and correlated poorly to site, stand and tree variables. This implies that it seems unfeasible to identify heartwood-rich stands or stems, e.g., for production of heartwood products, by using inventory data. Heartwood formation expressed as the number of new heartwood rings formed each year was found to increase with increasing cambial age, from about 0.5 rings per year at a cambial age of 45 years, to about 0.8 rings per year at a cambial age of 115 years.
  • Björklund, Swedish University of Agricultural Sciences, Department of Forest Management and Products, S-750 07 Uppsala, Sweden ORCID ID:E-mail: lars.bjorklund@sh.slu.se (email)
article id 676, category Research article
Erik Sundström. (1998). Afforestation of low-productive peatlands in Sweden – a tree species comparison. Silva Fennica vol. 32 no. 4 article id 676. https://doi.org/10.14214/sf.676
In 1970, five low-productive treeless peatlands in Sweden, ranging from latitudes 56°N to 67°N, were drained and fertilized for afforestation. The aim of the study was to determine the effect of four ditch spacings, varying from 7.5 to 60 m, and five NPK-fertilizer combinations, on the survival and growth of planted Scots pine (Pinus sylvestris), lodgepole pine (Pinus contorta), Norway spruce (Picea abies), and silver birch (Betula pendula) seedlings. The assessments were carried out 18–22 years after planting. Neither silver birch, nor Norway spruce was regarded suitable for the site type. The mortality of silver birch was almost complete, and Norway spruce did not grow well in any of the study areas, however, better than Scots pine in the north. Lodgepole pine had better height and diameter growth but also higher mortality rates than Scots pine. In the two northernmost experimental areas no response to fertilization was found. In the other three areas, the response to fertilization did not differ between species. Phosphorus was the most effective of the added fertilizer elements, whereas nitrogen showed no positive effect. Broadcast fertilizer application, with three times higher amount of fertilizer per ha gave the same growth response as spot application.
  • Sundström, Swedish University of Agricultural Sciences, Dept. of Silviculture, S-901 83 Umeå, Sweden ORCID ID:E-mail: erik.sundstrom@ssko.slu.se (email)
article id 674, category Research article
Tuula Aalto. (1998). Carbon dioxide exchange of Scots pine shoots as estimated by a biochemical model and cuvette field measurements. Silva Fennica vol. 32 no. 4 article id 674. https://doi.org/10.14214/sf.674
A biochemical model was used to calculate CO2 fluxes to Scots pine shoots in two boreal measurement stations, Hyytiälä in southern Finland (61°51’N, 24°17’E) and Värriö in northern Finland (67°46’N, 29°35’E). The results of the model were compared with cuvette measurements performed in field conditions. A differential equation for change in gas concentration inside a closed cuvette was constructed and solved in order to obtain conductances and fluxes. The results were generally in a good agreement, the correlation coefficients varied from 0.74 to 0.95. Some discrepancies were also found. The model followed more intensively changes in temperature. This could be seen in northern Finland measurements at low temperatures (< 18 °C). The modelled temperature response indicated low fluxes at low temperatures, but measurements did not show any decrease. The irradiation response was relatively similar in both measuring sites and according to the model. Cuvette measurements showed slightly smaller quantum yields as a result from shading of the needles. The temperature dependences of the biochemical model parameters Jmax and Vc(max) were re-evaluated from the field measurements. The results for Vc(max) agreed well with earlier estimations, while the results for Jmax indicated relatively high values at low temperatures especially in northern Finland. Exponential fitting produced also substomatal concentrations of CO2, which agreed quite well with the model. The daily minimum of substomatal/ambient concentration ratio varied from 0.4 to 0.8.
  • Aalto, Department of Physics, P.O. Box 9, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: tuula.aalto@helsinki.fi (email)
article id 681, category Research article
Virpi Palomäki, Alpo Hassinen, Matti Lemettinen, Timo Oksanen, Heljä-Sisko Helmisaari, Jarmo Holopainen, Seppo Kellomäki, Toini Holopainen. (1998). Open-top chamber fumigation system for exposure of field grown Pinus sylvestris to elevated carbon dioxide and ozone concentration. Silva Fennica vol. 32 no. 3 article id 681. https://doi.org/10.14214/sf.681
An open-top chamber fumigation system was built in a young Scots pine stand to study the effects of realistic elevated ozone (O3) and carbon dioxide (CO2) concentrations and their combination on trees in natural conditions. Doubled CO2 concentration compared to present ambient concentration, and O3 concentration between 40 ppb and 70 ppb in the first study year (1994) and doubled O3 concentration in years 1995 and 1996 were the target concentrations in the chambers. The O3 concentration in the chambers was successfully maintained close to the target concentration and differences between chambers were small. The mean CO2 concentration in the CO2 treatment was ca. 100 ppm below the target, but was maintained at this level throughout the growing season. Two degrees higher mean air temperature and slightly lower light intensity compared to open air were measured in the chambers. The operation of the fumigation system was satisfactory during the three study years and repeatability of the gas treatments can be regarded good in this low cost exposure system.
  • Palomäki, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland ORCID ID:E-mail: virpi.palomaki@uku.fi (email)
  • Hassinen, Mekrijärvi Research Station, FIN-82900 Ilomantsi, Finland ORCID ID:E-mail:
  • Lemettinen, Mekrijärvi Research Station, FIN-82900 Ilomantsi, Finland ORCID ID:E-mail:
  • Oksanen, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland ORCID ID:E-mail:
  • Helmisaari, Finnish Forest Research Institute, Department of Forest Ecology, P.O.Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail:
  • Holopainen, Agricultural Research Centre, FIN-31600 Jokioinen, Finland ORCID ID:E-mail:
  • Kellomäki, University of Joensuu, Faculty of Forestry, P.O.Box 111, FIN-80101 Joensuu, Finland ORCID ID:E-mail:
  • Holopainen, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland ORCID ID:E-mail:
article id 691, category Research article
Jacek Oleksyn, Mark G. Tjoelker, Peter B. Reich. (1998). Adaptation to changing environment in Scots pine populations across a latitudinal gradient. Silva Fennica vol. 32 no. 2 article id 691. https://doi.org/10.14214/sf.691
In several growth chamber and field experiments we examined the growth response of Scots pine (Pinus sylvestris L.) populations from a wide latitudinal range to temperature and photoperiod. The duration of the shoot elongation period of one-year-old seedlings was affected by temperature and photoperiod. In contrasting temperatures, 23/20 °C, 20/17 °C, and 17/14 °C (day/night), shoot elongation period for all populations was shortest in the high and longest in the low temperature treatments. The northern populations from 61–57°N ceased height growth earlier than the other populations in the southern 50°N photoperiod. The order of growth cessation among populations at 50°N in the chamber experiment and at 52°N in the field experiment was similar and related to observed population differences in terminal leader growth and total tree height. Since the length of growing season is under strong environmentally-mediated genetic control in Scots pine, potential climatic changes such as increasing temperature will probably alter the length and timing of growth in aboveground tree parts, but likely in the opposite direction (a shorter growing season) than has been often hypothesized (a longer growing season). Tree-ring analyses of a provenance experiment established in 1912 indicate that the main climatic factors that limited ring-width growth in Scots pine were air temperatures in the winter months of December through March. Low winter temperatures were followed by the formation of narrow rings over the next summer. Based on responses to temperature, Scots pine populations from the continuous European range can be divided in several geographic groups along a latitudinal gradient. Our results suggest that in developing new models to predict the response of Scots pine to changing environmental conditions, it is necessary to include intraspecific differentiation in acclimation and adaptation to environmental factors.
  • Oleksyn, Polish Academy of Sciences, Institute of Dendrology, Parkowa 5, PL-62-035 Kórnik, Poland; University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA ORCID ID:E-mail: oleks001@gold.tc.umn.edu (email)
  • Tjoelker, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA ORCID ID:E-mail:
  • Reich, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA ORCID ID:E-mail:
article id 690, category Research article
Bengt Persson. (1998). Will climate change affect the optimal choice of Pinus sylvestris provenances? Silva Fennica vol. 32 no. 2 article id 690. https://doi.org/10.14214/sf.690
Provenance experiments with Pinus sylvestris (L.) were evaluated in Sweden north of latitude 60°N. Survival and yield were determined as functions of temperature sum of the site and latitudinal origin of the provenance. Altitudinal origin was of negligible importance. The effects of latitudinal transfer were influenced by temperature sum at the growing site. At the harshest situated sites southward transfer longer than 3° was optimal for survival and yield, whereas transfer effects in a mild climate were weak. Climatic warming would reduce demands of hardiness. However, moderate differences in productivity are expected between formerly optimal seed sources and the ones adapted to changed climatic conditions. Since mortality usually was low in plantations older than 20 years or higher than 2 m, established stands are expected to be robust against adverse effects of climate change.
  • Persson, Högskolan Dalarna, S-781 88 Borlänge, Sweden ORCID ID:E-mail: bpn@du.se (email)

Category: Review article

article id 694, category Review article
Gösta Eriksson. (1998). Evolutionary forces influencing variation among populations of Pinus sylvestris. Silva Fennica vol. 32 no. 2 article id 694. https://doi.org/10.14214/sf.694
The evolutionary forces influencing genetic differentiation among populations are identified. Natural selection, random genetic drift, and mutations promote differentiation while phenotypic plasticity and gene flow delay or prevent differentiation. Evolution is a dynamic force which leads to instability and absence of any perfection in the adaptive process. Natural selection acts mainly on phenotypes and only indirectly on the components of important breeding traits. In the northern part of the distribution of Scots pine there is a large among- and within-population variation in survival. The high among-population variation occurs in spite of an assumed high gene flow. Biomass is a product of many components and it also shows a high population variation. Many markers are neutral and such markers will not reveal adaptive variation.
  • Eriksson, Swedish University of Agricultural Sciences, Department of Forest Genetics, Uppsala, Sweden ORCID ID:E-mail: gosta.eriksson@sgen.slu.se (email)
article id 693, category Review article
Erik G. Ståhl. (1998). Changes in wood and stem properties of Pinus sylvestris caused by provenance transfer. Silva Fennica vol. 32 no. 2 article id 693. https://doi.org/10.14214/sf.693
Wood properties focused in forest tree breeding should be of economic importance, have a large total variation and a high heritability. The properties of interest are those that influence the strength and durability of sawn products or the amount and properties of pulp produced. The following wood properties are treated: width of the annual ring, juvenile wood, late wood content, heart wood, tracheid dimensions, basic density, stem straightness and branch diameter. The provenance variation in wood properties can be related to differences in growth phenology. In the northern part of distribution P. sylvestris (L.) provenances transferred a few degrees southwards have a high survival and yield but stem wood production is low. Trees from these provenances will be straight and with few spike knots or other injuries. The shoot elongation period will be short and the temperature sum required for wood formation sufficient. Provenances transferred southwards will form thin annual rings, few and thin branches, little early wood, high basic density and slender tracheids with thick cell walls in comparison to local provenances. An example of the effect of alternative transfers on the yield and wood properties is evaluated. In regions with deviating climatic patterns alternative provenance transfer patterns may be better. The objectives of the land owner should influence the provenance choice. The importance of integrating tree improvement with silvicultural management is discussed with reference to spacing.
  • Ståhl, College of Dalarna, CITU Centre for Industrial Technology and Development, S-781 88 Borlänge, Sweden ORCID ID:E-mail: esl@du.se (email)

Category: Research note

article id 1661, category Research note
Āris Jansons, Linda Robalte, Roberts Čakšs, Roberts Matisons. (2016). Long-term effect of whole tree biomass harvesting on ground cover vegetation in a dry Scots pine stand. Silva Fennica vol. 50 no. 5 article id 1661. https://doi.org/10.14214/sf.1661
Highlights: After 47 years, whole tree harvesting (WTH) increased richness of ground cover species compared to conventionally managed stands; Higher occurrence of the oligotrophic species after WTH suggested reduction of soil nutrient content, hence formation of different plant community; WTH, apparently, facilitated recovery of species typical for later successional stages.

Long-term (47 years) effect of experimental whole tree harvesting (WTH) with a heavy soil scarification on ground cover vegetation was assessed in a dry nutrient-poor Scots pine (Pinus sylvestris L.) stand in Latvia. Neighbouring conventionally managed young (10 years) and mature (119 years) stands of the same type were used for comparison. Higher species richness was observed in the WTH stand compared to conventionally managed young and mature stands (24, 18 and 16 species, respectively), likely due to the profound disturbance. The Shannon diversity index was higher in the young than in the WTH and mature stands (2.36, 1.77 and 1.63, respectively); still, the composition and structure of ground cover vegetation in WTH was more similar to the mature stand. Nevertheless, the occurrence of oligotrophic species in the WTH stand suggested decreased soil nutrient content and potential development of different plant community. Hence, such method might be considered for restoration of oligotrophic stands. Nevertheless, the period of 47 years appeared sufficient for the ground cover vegetation to recover after the WTH.

  • Jansons, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: aris.jansons@silava.lv
  • Robalte, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: robalte.l@gmail.com (email)
  • Čakšs, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: chakijs95@gmail.com
  • Matisons, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: roberts.matisons@silava.lv
article id 1330, category Research note
Hanne K. Sjølie, Hans Asbjørn Kårstad Sørlie, Bjørn Tveite, Birger Solberg. (2015). The performance of two Swedish N fertilization functions evaluated on data from Norwegian fertilization experiments. Silva Fennica vol. 49 no. 4 article id 1330. https://doi.org/10.14214/sf.1330
Highlights: The performance of two predictive Swedish fertilization growth response functions was assessed on data from Norwegian fertilization experiments; One function performed well on the full dataset, but overpredicted the growth response in spruce plots and underpredicted in pine plots; The second function performed well in pine stands, but overestimated the growth response in spruce and in total.

This study compares the responses of two Swedish 5-year predictive stand-level functions with the observed responses in 721 fertilization experiment plots in Norway fertilized with nitrogen (N). All plots are single-species consisting of Norway spruce (Picea abies (L.) H. Karst.) or Scots pine (Pinus sylvestris L.) fertilized with ammonium nitrate (AN) or urea. The correlations between the observed and the two predicted responses were 0.34–0.40 for all plots taken together. One response function performed well on average, but underestimated the response in pine plots and overestimated the response in spruce plots. The second function overpredicted the response on the full dataset, in spruce plots and old forest, but performed well in pine plots. Both functions overestimated the growth response in high-productive plots. Higher N deposition in Norway than in Sweden may count for parts of the deviations. Testing of fertilization functions on new datasets is rare, but important part of the evaluation of functions. As the functions are not well fit for predicting the growth response in spruce and high-productive plots in our sample, new functions that include N deposition are welcome.

  • Sjølie, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway ORCID ID:E-mail: hanne.sjolie@nmbu.no (email)
  • Sørlie, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway ORCID ID:E-mail: hans.asbjorn.sorlie@slf.dep.no
  • Tveite, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail: bjorn.tveite@skogoglandskap.no
  • Solberg, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway ORCID ID:E-mail: birger.solberg@nmbu.no
article id 402, category Research note
Miina Rautiainen, Pauline Stenberg, Tiit Nilson. (2005). Estimating canopy cover in Scots pine stands. Silva Fennica vol. 39 no. 1 article id 402. https://doi.org/10.14214/sf.402
The way canopy cover is defined and measured influences the obtained canopy cover percentage. Estimates of canopy cover are needed, for example, in canopy radiation modelling and remote sensing applications and as a tool for political decision-making. In this paper, we demonstrated the use of two methods, the LAI-2000 Plant Canopy Analyzer instrument and the Cajanus tube, in Scots pine stands for canopy cover estimation, and also assessed the number of measurement points required for reliable estimates. The Cajanus tube yielded slightly larger canopy closure values than the LAI-2000 instrument, but the values were nevertheless in good agreement. Both of the methods required approximately 250 measurement points for canopy closure estimates of a stand to become relatively stable. We also present the first measured effective canopy transmittance values for Scots pine stands in Finland and an example of tree pattern mapping with the Cajanus tube.
  • Rautiainen, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: miina.rautiainen@helsinki.fi (email)
  • Stenberg, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Nilson, Tartu Observatory, EE-61602 Tõravere, Tartumaa, Estonia ORCID ID:E-mail:
article id 679, category Research note
Hans-Örjan Nohrstedt, Gunnar Börjesson. (1998). Respiration in a forest soil 27 years after fertilization with different doses of urea. Silva Fennica vol. 32 no. 4 article id 679. https://doi.org/10.14214/sf.679
A number of previous studies have shown that N fertilization often reduces respiration in forest soils. However, the durability of this effect has not been fully explored. In this study, the response of soil respiration to a single fertilization with urea, applied 27 years earlier, was examined in a field experiment located in a stand of Pinus sylvestris in central Sweden. The doses that had been added were 120, 240 and 600 kg N ha–1. Samples were taken from the humus layer and the upper 7.5 cm of the mineral soil. Sieved samples were incubated in the laboratory. No effect of the previous fertilization on soil respiration was found, thus indicating that the reduction shown in earlier studies is not persistent. There was a tendency that the highest N dose had caused a higher N concentration and a lower C/N-ratio in the humus layer and a higher C concentration in the mineral soil.
  • Nohrstedt, The Forestry Research Institute of Sweden, Uppsala Science Park, S-751 83 Uppsala, Sweden ORCID ID:E-mail: hans-orjan.nohrstedt@skogforsk.se (email)
  • Börjesson, Department of Microbiology, Swedish University of Agricultural Sciences, P.O. Box 7025, S-750 07 Uppsala, Sweden ORCID ID:E-mail:
article id 702, category Research note
Timo Kurkela, Heikki Nuorteva. (1998). Short-needle disease of Scots pine: an abnormal needle length distribution. Silva Fennica vol. 32 no. 1 article id 702. https://doi.org/10.14214/sf.702
Short-needle syndrome occurs commonly in southern Finland. The disease is characterized by abnormal length distribution of the needles in shoots. In most cases, affected shoots have needles of normal length as well as very short needles. The short needles are those injured during the needle elongation period; the tissues formed abnormal sclerenchymatic structures and wound periderm. One possible cause could be hemipterous insects feeding on growing needles. Salivary sheaths of such insects were often present in both deformed needle bases and undeformed mature tissues.
  • Kurkela, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail: timo.kurkela@metla.fi (email)
  • Nuorteva, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail:

Category: Article

article id 7173, category Article
Erkki Lähde. (1966). Studies on the respiration rate in the different parts of the root systems of pine and spruce seedlings and its variations during the growing season. Acta Forestalia Fennica vol. 81 no. 8 article id 7173. https://doi.org/10.14214/aff.7173

In this study an attempt was made to use manometric Warburg technique in studying the growing season variations in the respiration rates of the roots of 1–3-year-old seedlings of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.). The respiration rates in both short-roots and long-roots have also been investigated.

According to the results, respiration intensity was the greatest in Scots pine and Norway spruce short-roots but also considerable in the long-root tips at the points of elongation. When the oxygen uptake rate per weight unit in the pine short-roots is given value of 100, the rate in the long-root tips is 61 and in the basal area 36. The corresponding values for spruce are 100, 69 and 43. The relative carbon dioxide release rates are different for the basal parts of the long-roots: pine 53 and spruce 57, when the CO2 release from the short-roots is 100. The CO2 release rate in the basal parts of the long-roots is relatively greater than the oxygen uptake. The respiration rate of the root systems of pine was larger than that of spruce due to the larger size of the root system.

The respiration rate per unit weight of pine roots of the 1- to 3-year-old seedlings decreases significantly with the increasing age. In spruce, the decrease was smaller. The result could have been different if only the short-roots of the same growing season were studied from all seedlings.

During the first growing season the root respiration rate decreased from the middle of the summer towards autumn. An experiment with pine seedlings grown in the mineral soil showed a very rapid increase in respiration rate in the spring. The rate, especially oxygen uptake, is at its greatest in the roots at the time of fastest growth.

  • Lähde, ORCID ID:E-mail:
article id 7170, category Article
Yrjö Ilvessalo. (1967). Luonnonnormaalien metsiköiden kehityksestä Kainuussa ja sen lähiympäristössä. Acta Forestalia Fennica vol. 81 no. 5 article id 7170. https://doi.org/10.14214/aff.7170
English title: The development of natural normal forest stands in southeastern Northern Finland.

Examination of stands developed under natural conditions can be used to provide basis for comparison for study of the development and yield of stands treated with intermediate fellings. In Finland, the first investigation and the yield and the structure of natural normal stands were published in 1920. This investigation on development and yield of the natural forests of Kainuu in southeastern Northern Finland is based on 92 sample plots on three forest types; Empetrum-Vaccinium type (EVT), Empetrum-Calluna type (ECT) and Vaccinium-Myrtillus type (VMT).

The Scots pine (Pinus sylvestris L.) sample plots represented variation of age classes for construction of mean development series. The Norway spruce (Picea abies (L.) H. Karst.) of the region are so old that development series could be obtained only for dominant trees based on stem analysis.

The average development of Scots pine stand on EMT type within the region is on average more rapid and the yield in cubic volume quantitatively larger and structurally better than that on ECT type. Self-thinning during the early decades of EVT is slower. The pine stands are denser in the age of 70 in Kainuu compared to Central Northern Finland, but the development and yield are similar.

The development, yield and structure of natural Norway spruce stand on VMT proved considerably inferior to the average level of pine stands on EVT, and to a major part on ECT. The mixed pines on spruce sample plots have developed better than spruces of equal age. Spruce stands on VMT in the area developed markedly better than Geranium-Dryopteris-Myrtillus (GDMT) in Central Northern Finland.

It seems that a spruce stand seems to require more fertile site type in north than in the southern part of Finland. These fertile types are relative rare in the north. In the region, the best results are received with pine. As a rule, also the yield of birch (Betula sp.) is poor in the region.

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  • Ilvessalo, ORCID ID:E-mail:
article id 7166, category Article
J. E. Hårdh. (1966). Trials with carbon dioxide, light and growth substances on forest tree plants. Acta Forestalia Fennica vol. 81 no. 1 article id 7166. https://doi.org/10.14214/aff.7166

Growth-promoting effects of enhanced caron dioxide levels upon forest tree seedlings grown in plastic houses was studied in 1964 and 1965 in the Forest Breeding Foundation in Haapastensyrjä near Loppi in Southern Finland. In both years more vigorous height and weight growth, and development of root system was achieved when the CO2 concentration was increased to 0.2% than in the normal conditions (CO2 0.03%). The CO2 concentration was increased by burning propane in the plastic houses. Burning continued for four hours per day either at 8–10 and 14–16 a clock or 6–10 a clock. Growth was not affected by the time of the treatment, and it was equally high in 0.1% and 0.2% concentrations.

Treatment of the seedlings with 100–200 ppm gibberellic acid (GA) increased the height growth of healthy, well-rooted seedlings. Treatment with a concentrated (600 ppm) dosage, as well as treatment with a combination of GA and 1-naphtyl acetic acid (NAA) caused serious defects in grafts of Scots pine (Pinus sylvestris L.). GA treatments did not induce flower formation in pine. Red light during the night seemed to enhance growth of grafts of silver birch (Betula pendula Roth) and Norway spruce (Picea abies (L.) H. Karst.).

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  • Hårdh, ORCID ID:E-mail:
article id 7164, category Article
Veijo Heiskanen. (1965). Puiden paksuuden ja nuoruuden kehityksen sekä oksaisuuden ja sahapuulaadun välisistä suhteista männiköissä. Acta Forestalia Fennica vol. 80 no. 2 article id 7164. https://doi.org/10.14214/aff.7164
English title: Relation between the development of the early age and thickness of trees and their branchiness in Scots pine stands in Finland.

The objective of the study was to establish the influence of the founding density of a stand and the intensity of intermediate cutting on the quality of pine saw logs stems, primarily on their branchiness. Measurements were carried out in 68 Myrtillus-type and 32 Vaccinium-type Scots pine (Pinus sylvestris L.) stands. The quality of 1,982 sample trees was assessed.

According to the results, the branchless part of the stem is longest in the older age classes of trees. In all age classes the percentage of the branchless part is highest in medium sized stems. The relative height of the crown limit is greatest in small diameter classes and continues as the thickness of the tree increases. The crown is longer in the thicker tree. The grade of the butt log is on average highest in medium sized stems. Knottiness of a log made it unsuitable for a saw log only among the thickest stems. The relative share of the u/s grade decreased as the thickness of the trees increased.

From the point of view of early development of the trees it was concluded that in all age classes the branchless part is the shorter the faster the tree has grown in diameter when it was young. Also, branches of the butt log are the bigger the faster the tree has developed when it was young. The grade of the butt log improves as the thickness of the annual rings diminishes.

To produce good quality sawn timber, the pine stands should be established dense, and the first thinnings should be delayed as much as possible. The best time for the thinning would be when the diameter of the dominant trees at stump height is 12–15 cm and when all the branches have died on the length of the butt log. After the first thinning, comparatively intense intermediate thinning may be applied.

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  • Heiskanen, ORCID ID:E-mail:
article id 7161, category Article
Olavi Laiho. (1965). Further studies on the ectendotrophic mycorrhiza. Acta Forestalia Fennica vol. 79 no. 3 article id 7161. https://doi.org/10.14214/aff.7161

There has not been complete agreement as to what is meant by ectendotrophic mycorrhizae, and there is a wide variety of opinion among authors on mycorrhizal terminology. In this paper ectendotrophic mycorrhizae are defined to be short roots with Hartig net and intracellular hyphae in the cortex. A mantle and digestion of intracellular hyphae may be found but are not necessary. In the study of Mikola (1965) ectendotrophic mycorrhiza was found to be common in Scots pine (Pinus sylvestris L.) seedlings in Finnish nurseries. The mycorrhizae had always similar structure and the mycelium isolated from the seedlings (E-strains) was similar. The aim of this study was to find out what kind of ectendotrophic mycorrhizae exist in forests and nurseries outside Finland, what kind of mycorrhizae do the E-strains isolated from Scots pine form with other tree species, and are these associations symbiotic.

Only one type of ectendotrophic mycorrhiza was found on the 600 short roots collected from the continents of Europa and America. The type was similar to the one described by Mikola: the mycelium is coarse and forms a strong Hartig net, and intracellular infection is heavy. Evidence is convincing that this structure was formed by the same fungus species. The species is unidentified. Mycorrhizae synthesized by E-strain with six spruce species, fir, hemloch and Douglas fir were all ectotrophic.

The E-type ectendotrophic mycorrhizae proved to be a balanced symbiosis. The seedlings of 13 tree species inoculated with the E-strain grew in the experiment better than the controls. The observation that ectendotrophic mycorrhizae dominates in the nurseries but is seldom found in forests, and then only in seedlings growing in the forest, was confirmed in the study. In synthesis experiments E-strain formed either ecto- or ectendotrophic mycorrhiza depending on the tree species.

  • Laiho, ORCID ID:E-mail:
article id 7160, category Article
Peitsa Mikola. (1965). Studies on the ectendotrophic mycorrhiza of Scots pine in Finland. Acta Forestalia Fennica vol. 79 no. 2 article id 7160. https://doi.org/10.14214/aff.7160

The differences between different types of mycorrhiza; endomycorrhiza, ectomycorrhiza and ectendomycorrhiza, and the use of the terms have been variable in the earlier research. Studied of mycorrhiza in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seedlings may suggest that the conditions affect which kind of mycorrhiza develops in the seedlings. This study is aimed mainly at finding out whether the difference of ectotrophic and ectendotrophic mycorrhizae depends on fungal symbionts or envirionmental conditions. Furthermore, the occurrence of ectendotrophic mycorrhiza in Finland under various conditions was studied, and experiments on the physiology and ecology of the mycorrhiza and the fungal partner were conducted.

The ectendotrophic mycorrhiza as described in this paper has proved to be very common on Scots pine in Finnish nurseries, but it was not found in Norway spruce seedlings. The results did not support the hypothesis presented in some earlier studies that ectendotrophic mycorrhiza is more parasitic than the other mycorrhizal fungi. The nursery survey showed that no correlation existed between the size and vigour of the seedlings and the presence of ectendotrophic mycorrhiza. Furthermore, greenhouse-grown seedlings with and without the fungus grew equally well. The type of mycorrhiza was, however, almost exclusively confined to young (1–3-years-old) seedlings and to nursery soils. The experiments indicates also that ectendomycorrhizal fungus has a very wide ecological amplitude in regard to light intensity, soil fertility, acidity, and humus content. It has, however, a weak competitive ability in natural forest soils against the indigenous fungal population. When the seedlings were transplanted from the nursery to forest soil, their mycorrhizal population was largely changed.

  • Mikola, ORCID ID:E-mail:
article id 7158, category Article
Olavi Huuri. (1965). Männyn- ja kuusenkäpyjen varastoinnin vaikutus niistä saatavan siemenen itävyyteen. Acta Forestalia Fennica vol. 78 no. 5 article id 7158. https://doi.org/10.14214/aff.7158
English title: The effects of storage in cones on the viability of pine and spruce seeds.

Seed storing experiments with cones of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) were conducted in Oitti seed extracting plant in Southern Finland from February to December 1955. The pine cones were stores for 267 and the spruce coned for 304 days. In four of the storage methods the cones were packed in sacks and another four in wooden boxes. Sample of cones were taken once a month, seeds were extracted and the germinative capacity was tested. The remaining extracted seeds were placed in storage, and in January 1956 moved to cold seed cellar until 1962, when the viability of the seeds was tested.

According to the results, cleaned pine cones can be stores for at least nine months using almost all methods of storage which are commonly used at our seed traction plants, without hazarding the usability of the seeds. The seeds in spruce cones, however, seemed to be more sensitive to conditions during the storage. The germinative capacity of the spruce seeds began to decrease after the beginning of May. Later the seeds were infected with mould, which increased towards the end of the experiment.

Thus, preservation of the germinative capacity of the seeds of pine and spruce requires storage in different conditions. The results suggest that extraction of spruce seeds should be finished during the cold winter months. It seems that seed in the cones of pine and spruce endure storage in piles of paper or cloth sacks at least as well as in wooden boxes. Occasional warming of the storage, snow and foreign material among the cones and an over meter thick cone layer decreased the germinative capacity of spruce seeds during spring and summer. Spruce seeds that had been extracted immediately after collecting of the cones preserved their germinative capacity well during an eight years storage period.

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  • Huuri, ORCID ID:E-mail:
article id 7157, category Article
Leo Heikurainen, Kustaa Seppälä. (1965). Regionality in stand increment and its dependence on the temperature factor on drained swamps. Acta Forestalia Fennica vol. 78 no. 4 article id 7157. https://doi.org/10.14214/aff.7157

The aim of this work was to study, on the basis of material published earlier (Heikurainen 1959), the effect of temperature on stand increment, to find out if there is any differences between Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.), and to study the effect of site quality on the relationship between stand increment and temperature. The calculations were based on data collected from 396 sample plots on drained peatlands in different parts of Finland.

There seemed to be no differences due to tree species or site quality in the relative amounts of growth under different climatic conditions. Thus, differences in the absolute growth between poor and fertile sites are noticeably smaller in Northern Finland than in Southern Finland. The author suggests that this implies that the lasting maximal increase of growth which can be produced, for instance, by using soil-improving agents must be less in unfavourable conditions than in favourable.

  • Heikurainen, ORCID ID:E-mail:
  • Seppälä, ORCID ID:E-mail:
article id 7156, category Article
Tauno Kallio. (1965). Tutkimuksia maannousemasienen leviämisbiologiasta ja torjuntamahdollisuuksista Suomessa. Acta Forestalia Fennica vol. 78 no. 3 article id 7156. https://doi.org/10.14214/aff.7156
English title: Studies on the biology of distribution and possibilities to control Fomes annosus in Southern Finland.

The aim of this investigation was to clarify aerial infection of Fomes annosus (now Heterbasision annosum) in the cross-sections of stumps of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) in Southern Finland. In addition, an attempt was made to study possibilities to reduce an eventual aerial infection by means of spreading various protecting substances on the cross-section of the stumps immediately after cutting. The stumps were treated withs creosote, ceruse (lead white) and a product named ”Ventti”, which active constituent is copper. The effect of prescribed burning of the site on the aerial spreading of the fungus was studied.

Five sample plots were located in spruce stands and one in a pine stand. One of the spruce stands was prescribed burned. Samples were taken from the stumps 14–17 and 24–29 months after cutting. To identify the fungi, the samples were cultivated on a nutrient substrate in laboratory conditions. The results show that Heterobasidion annosum had spread by air to cross-sections of stumps of spruce. 11.5% of the samples taken from the spruce stumps 14–17 months and 17% of samples taken 24–29 months after cutting were infected. Burning of the site reduced strongly the aerial infection of stumps by the fungus. The stumps of Scots pine were not infected by Heterobasidion annosum in this study. The infection could be limited by treating the cross-sections with substances that are used to prevent growth of mould.

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  • Kallio, ORCID ID:E-mail:
article id 7151, category Article
Peitsa Mikola, Olavi Laiho, Jorma Eerikäinen, Kari Kuvaja. (1964). The effect of slash burning on the commencement of mycorrhizal association. Acta Forestalia Fennica vol. 77 no. 3 article id 7151. https://doi.org/10.14214/aff.7151

Prescribed burning is a common silvicultural practice in northern Europe, intended to destroy the slash and ground vegetation and to reduce the thickness of the raw humus layer prior reforestation. The purpose of the experiments was to study whether there are any differences in the commencement and early development of mycorrhizal infection between burned and unburned areas. A clear-cutting area was burned on May 1961. The soil was rocky moraine, the forest type was Vaccinium type. Two weeks after burning Scots pine (Pinus sylvestris L.) was sown in patches.

According to the results, mycorrhizal infection took place on the unburned area earlier than on the burned. The difference was relatively small, perhaps 1–2 weeks. Although burning kills mycorrhizal fungi, it did not cause serious harm to the seedlings, on the contrary, the favourable influence of burning was more distinct. The high temperatures caused by the fire are restricted in the soil in a prescribed burning only a few centimetres deep. Although the mycorrhizal fungi are concentrated in a very thin surface layer of the soil, some mycorrhizae are situated deeper, and from there the fungi are able to infect roots and spread back to the surface layer. The fire also rises the pH of the soil, which can be harmful for mycorrhizal fungi. Even this effect, however, is limited to a thin surface layer.

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  • Mikola, ORCID ID:E-mail:
  • Laiho, ORCID ID:E-mail:
  • Eerikäinen, ORCID ID:E-mail:
  • Kuvaja, ORCID ID:E-mail:
article id 7150, category Article
Olavi Laiho, Peitsa Mikola. (1964). Studies on the effect of some eradicants on mycorrhizal development in forest nurseries. Acta Forestalia Fennica vol. 77 no. 2 article id 7150. https://doi.org/10.14214/aff.7150

Mycorrhizal association is a characteristic feature of the trees of the northern coniferous forests. The purpose of the present study was to determine what influence some fungicides and herbicides regularly used in Finnish nurseries have on formation and development mycorrhizal in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seedlings. The results are based mainly on field experiments in nurseries. First the initiation of mycorrhiza was described in untreated seedlings.

In the first growing season mycorrhizal infection commences fairly late even under normal conditions, i.e. 6–7 weeks after seeding and 3–4 weeks after the formation of the first short roots. Soil disinfectants are commonly used in nurseries before seeding, and they are supposed to evaporate or disintegrate in a few days or 1–2 weeks. In pure culture experiments mycorrhizal fungi proved several times more sensitive than parasitic and indifferent soil moulds to herbicides and fungicides, but in field experiments the delay of mycorrhizal infection caused by them does not seem to harm the seedlings. In the second summer differences of mycorrhizal relations between treated and control plots disappeared. Accordingly, the influence of biocides on mycorrhizae, when applied in the customary concentrations, does not extend beyond the first growing season.

Methyl bromide and SMDC retarded mycorrhiza formation distinctly, while formaldehyde and allyl alcohol had no effect. Apart from not retarding mycorrhizae, formaldehyde and allyl alcohol promoted seedling growth and favoured Trichoderma viride in the soil. Trichoderma is known to be antagonistic to many fungi.

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  • Laiho, ORCID ID:E-mail:
  • Mikola, ORCID ID:E-mail:
article id 7148, category Article
Maunu Seppänen. (1964). Vesisateen jakautumisesta männiköissä. Acta Forestalia Fennica vol. 76 no. 8 article id 7148. https://doi.org/10.14214/aff.7148
English title: Distribution of rainfall in the Scots pine stand in Central Finland.

Distribution of rainfall in in a Scots pine (Pinus sylvestris L.) stand and in an open place in Alajärvi in Central Finland was studies in 1959–1960. Density of the about 80 years old stand was 0.36 and the height of the trees 8–14 m. The dependence of throughfall and dependence of stemflow on 24-hour precipitation, and dependence of the distribution of 24-hour precipitation on the amount and nature of precipitation was calculated.

The precipitation of the crown of the forest depended on the rainfall. When the rainfall in the open place was over 7 mm, the rainfall within the forest was in average 89% of the rainfall in the open place, but if the rainfall in the open place was less than 1 mm, the rainfall within the forest was only 64% of that in the open place. Total stemflow in the pine stand was only 0.4%, and interception loss was 13.6%.

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  • Seppänen, ORCID ID:E-mail:
article id 7135, category Article
Paavo Yli-Vakkuri. (1961). Kokeellisia tutkimuksia taimien syntymisestä ja ensi kehityksestä kuusikoissa ja männiköissä. Acta Forestalia Fennica vol. 75 no. 1 article id 7135. https://doi.org/10.14214/aff.7135
English title: Experimental studies on the emergence and development of tree seedlings in spruce and pine stands.

This paper aims at studying regeneration of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) by sowing and natural regeneration of birch (Betula sp.) in Western Finland.

Germination of spruce and pine seeds may be prevented by dryness and temperatures below the optimum for germination. In natural conditions, when temperature and moisture is insufficient for germination, the type of seedbed generally has en effect on germination result. Trenching of the seeding spots showed that root competition during the early stage of regeneration was not of decissive importance. It seemed to, however, improve the preservation of the seedlings later. It is common that it can take long before the seeds germinate, and during that time the number of viable seeds decrease strongly.

Also, the seedling stock quickly began to decrease in number after germination, especially during the first growing season and the following winter. The decrease was larger in intact vegetation than on mineral soil or in the humus layer. The emerging seedlings were destroyed by drought very easily, but their tolerance to drought improved later on.

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  • Yli-Vakkuri, ORCID ID:E-mail:
article id 7130, category Article
Paavo Yli-Vakkuri. (1961). Tutkimuksia männyn kylvöalojen metsittymisvaiheesta. Acta Forestalia Fennica vol. 74 no. 3 article id 7130. https://doi.org/10.14214/aff.7130
English title: Studies on the development of young sown pine stands in Central Finland.
Original keywords: uudistaminen; kylvö; mänty; taimikko

In this paper the development of sown Scots pine (Pinus sylvestris L.) seedling stands into forests is studied. The material was collected in stands sown in 1930–1940 in private forests in the Forestry Board districts of Central and Northern Ostrobothnia. The 119 areas, including both burned and other areas, were studied in 1955.

Most seedings had been carried out on relatively poor soils, mostly representing Vaccinium and Calluna type forests. 71% of the areas consisted of large forest fires, mostly from 1933. The most burned areas did not have seed producing trees nearby. The other sown areas were in general small, 1–2 ha, and near forests capable of producing seeds. The species of previous tree generation, in the older areas mostly pine and in the younger areas Norway spruce, affected tree species composition of the new tree generation.

Over 90% of the burned areas were in silviculturally good or satisfactory condition, while the main part of the other sown stands was in fair or poor condition. Weeding and thinning had been done only in the oldest stands. Most stands had been left untended. Natural new trees often competed with the sown pines, and cull-trees and border forest increased natural regeneration in the areas. In Calluna type the poor soil limited regeneration and growth of broadleaf trees. The worst competitors were naturally regenerated pine seedlings both on Calluna and Vaccinium type. On Vaccinium type also birch and sometimes also aspen (Populus tremula L.) competed with sown pine. On better sites and paludified areas competition by broadleaf trees increased. The rhythm of development of broadleaved trees is so different from pine that only those broadleaved trees that are formed in the stand when the pine seedlings are larger can develop harmoniously with pine. Due to the harmful competition, the seedling stands should be tended early on. In addition, it may be advisable to abandon the practise to leave trees on sowing areas.

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  • Yli-Vakkuri, ORCID ID:E-mail:
article id 7128, category Article
Paavo Yli-Vakkuri. (1961). Emergence and initial development of tree seedlings on burnt-over forest land. Acta Forestalia Fennica vol. 74 no. 1 article id 7128. https://doi.org/10.14214/aff.7128

Prescribed burning has been used in regeneration areas in Finland as a method to treat the humus layer and creating more favourable chemical, physical and biological conditions for the seedlings. At the same time, fire clears away seedlings and shoots of unwanted trees and other vegetation. Direct sowing or planting, mostly Scots pine (Pinus sylvestris L.), seldom natural regeneration, is used. In this paper, the initial stages of the formation of a new tree generation of Scots pine and Norway spruce (Picea abies (L.) Karst.) on prescribed burned areas is studied in Central Finland in 1956–1960.

The burned area remains almost without vegetation for about two growing seasons. Conditions on a burned area which has not been tiled are very unfavourable for germination of seeds of coniferous and deciduous trees. On the other hand, shoots of deciduous trees occur soon after burning. Conditions for regeneration were found to be better 3–5 years after burning. Removal of humus layer in spots improved regeneration. However, the patches facilitated also natural regeneration of Norway spruce and especially birch (Betula sp.), which compete with Scots pine seedlings.

Continuous rainy periods improved the germination of Scots pine and Norway spruce seeds sown on the humus layer. Pine and spruce developed more rapidly on the exposed soil, however, young seedlings were easily destroyed. Seed eaters destroyed the pine and spruce seeds sown on the humus layer of newly burned areas completely or almost completely. The viability of pine seeds sown on the burned humus layer did not decrease for three weeks, but the viability greatly weakened after six or more weeks. Spruce seeds lost their viability faster than pine seeds.

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  • Yli-Vakkuri, ORCID ID:E-mail:
article id 7119, category Article
Paavo J. Ollinmaa. (1960). Eräistä ojitetuilla soilla kasvavan puun fysikaalisista ominaisuuksista. Acta Forestalia Fennica vol. 72 no. 2 article id 7119. https://doi.org/10.14214/aff.7119
English title: Physical properties of wood growing on drained peatlands.

The objective of the investigation was to determine the differences between faultless timber grown on a peatland before and after draining, in respect of compressive strength to the grain, volume weight, and shrinkage. In addition, the influence of the boundary zone between the close-ringed wood formed before draining and the wide-ringed wood produced after draining on strength of the timber was studied. The material consisted of 15 sample trees of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), white birch (Betula pubescens Ehrh.) and silver birch (B. Pendula Roth).

The volume weight of wood of the tree species in ascending order is; spruce, pine, white birch, silver birch. The volume weight of Scots pine seems to decrease from the butt end upwards, while no trend was revealed for spruce. In the coniferous trees, the wide-ringed wood formed subsequent to draining was slightly lighter than the close-ringed wood produced prior draining. No distinct trend was seen in the birch species. The volume weight of pine and spruce increased with decreasing width of the growth rings up to a certain limit, after which the conditions inverted.

The compressive strength of the different kinds of wood seems to increase from the butt end upwards, but after height of two meters it begins to decrease considerably. In birch, this point of inversion is in somewhat greater height. In spruce timber, the compressive strength parallel to the grain is lowest for wood which contains exclusively wide-ringed wood formed after draining. The boundary zone between the woods formed before and after draining is very distinguishable, but has no remarkable influence on the compressive strength parallel to the grain. Shrinkage of close-ringed wood is higher in all three principal directions than that of wide-ringed wood. This can be explained by the variations in volume weight and fibrillar orientation of the tracheid walls.

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  • Ollinmaa, ORCID ID:E-mail:
article id 7118, category Article
Paavo J. Ollinmaa. (1959). Reaktiopuututkimuksia. Acta Forestalia Fennica vol. 72 no. 1 article id 7118. https://doi.org/10.14214/aff.7118
English title: Study on reaction wood.

Compression wood of the tree species studied in this investigation, Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and common juniper (Juniperus communis L.), was found to be characterized in its cross section by the thick walls and rounded shape of its tracheids and the profuse occurence of spaces. Tension wood of aspen (Populus tremula L.) and alder (Alnus incana (L.) Moench) was found in microscopic examination to be characterized by the gelatinous appearance of the wood fibres, by its small cell cavities and by the thickness and buckling of the inner layer of the cecondary wall. Tracheids of the compression wood were found to have shorter length than normal on an average, while the tension wood fibres were found to be longer.

The microchemical studies suggest a higher than normal lignin content in compression wood and lower than normal lignin content in tension wood, as compared to normal wood. The reverse would be true for the cellulose contents. Volume weight of absolute dry reaction wood was distinctly higher than that of normal wood. The longitudinal shrinkage of reaction wood, particularly of compression wood, is several times that of normal wood. Transversal shrinkage of compression wood is much less than normal wood. Swelling tests revealed pushing effect of compression wood on elongation and pulling effect on tension wood on constraction. Volume shrinkage of compression wood is less than that of normal wood, in contrast to tension wood. The strength of compression wood in absolutely dry condition was nearly same as that of normal wood.

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  • Ollinmaa, ORCID ID:E-mail:
article id 7116, category Article
Kustaa Kallio. (1960). Metsikön taksatorinen tiheys keskipituuteen ja tiheyteen perustuvassa kuutiomäärän arvioinnissa. Acta Forestalia Fennica vol. 71 no. 7 article id 7116. https://doi.org/10.14214/aff.7116
English title: The mensurational density of a stand in estimating the volume on the basis of the mean height and the density class.

In Finland ocular estimation of the growing stock has been made by means of volume tables based on the mean height and density class, or on the dominant height and density class of the stand. The author has observed that if the volume of a stand is estimated by employment of both tables, the results vary markedly from one another. Furthermore, volume of fully stocked stands in the dominant height tables show an approximate correspondence with the volumes of managed normal stands in Southern Finland.

The purpose of this study is therefore to develop volume tables for coniferous trees, based on the density class and the mean height; these tables should give the same volume for a stand as the dominant height tables.

Volume per hectare of 187 Scots pine (Pinus sylvestris L.) stands and 120 Norway spruce (Picea abies (L.) Karst.) stands on different forest types were estimated using the relascope method in Southern Finland. With the volume and the measured mean and dominant heights as a basis, the density classes were extracted from both mean height tables and the dominant height tables. The investigation indicates that the author estimated the dense stands too thinly, and the thin ones too densely, and that the erroneous estimation of the density can be corrected by comparison of the ocular estimations and the corresponding measurements. The density can be measured by means of crown closure, stem number per hectare or the basal area per hectare.

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  • Kallio, ORCID ID:E-mail:
article id 7114, category Article
Paavo Yli-Vakkuri. (1960). Metsiköiden routa- ja lumisuhteista. Acta Forestalia Fennica vol. 71 no. 5 article id 7114. https://doi.org/10.14214/aff.7114
English title: Snow cover and ground frost in Finnish forests.

Snow cover and ground frost was studied in 29 forest stands in Southern and Central Finland in 1957–1959. The tree species influenced greatly accumulation of snow on the forest floor. Norway spruce (Picea abies (L.) Karst.) retains snow in its crown. In addition, snow and water falling from the branches compress the snow cover under the trees, and the ground freezes deeper because of the shallow snow cover. In the spring, the dense crown prevents rain and radiation reaching the ground, which remains cold longer. However, ground frost may protect spruce, which has a weak root system, from wind damages.

Scots pine (Pinus sylvestris L.) has similar, but milder, effects on snow cover within the forest. The crowns of pine seedlings and young trees pass snow easily, but later the crowns intercept it considerably. The lower branches are, however, high up and the snow is evenly spread on the ground. The deciduous trees intercept little snow and in the spring the snow smelts and the frozen soil thaws early. The snow conditions of deciduous forests are, however, changed by a spruce undergrowth.

It can be assumed that the unfavourable conditions in spruce forests can be alleviated by thinning. Also, mixture of pine and deciduous trees can transform the conditions more favourable in the spruce stands.

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  • Yli-Vakkuri, ORCID ID:E-mail:
article id 7112, category Article
Kustaa Kallio. (1960). Etelä-Suomen kylvömänniköiden rakenteesta ja kehityksestä. Acta Forestalia Fennica vol. 71 no. 3 article id 7112. https://doi.org/10.14214/aff.7112
English title: Structure and development of Scots pine stands established by sowing in Southern Finland.

In Southern Finland Scots pine (Pinus sylvestris L.) is mainly sown on Vaccinium and Myrtillus-type sites. The material for the study was collected by measuring sample plots in pure, even-aged pine stand that had been sown. The sample stands had been thinned from below.

The volume of the stands was roughly the same as that of repeatedly thinned pine stands. The cubic volume of sown pine stands is 65–90%, varying according to age, of that of natural-normal pine stands. The current annual volume increment of stands on Myrtillus-type was 8–9 m3/ha at age of 20–30 years. The peak was reached at age of 35 years with 9 m3/ha, in the following years the increment is about 8 m3/ha until the age of 60 years. On Vaccinium type sites increment reaches 6–7 m3 level at age of 30 years, and attains the peak of 7 m3/ha at the age of 45 years. Annual increment was in young and middle-aged Myrtillus-type stands about 10% greater, and on Vaccinium-type stands 15–20% greater than in natural-normal pine stands.

The total volume increment in 70 years old Myrtillus-type stands was 580 m3/ha over bark, and in 80 years old Vaccinium-type stands 520 m3/ha. The total removal on Myrtillus-type sites totalled nearly 350 m3/ha in sown pine stands up to 70 years of age, and 280 m3/ha on Vaccinium-type stands. The total yield in sawn timber per hectare rises up to 6,300 cubic ft in a 70 years old stand on Myrtillus-type stands, and 5,300 cubic ft in Vaccinium-type stands. In conclusion, the volume and increment development of managed pine stands established by sowing up to 70–80 years of age is largely the same as in repeatedly thinned pine stands, but the structure and yield offer greater advantages. The investigation demonstrates that, in the case of Scots pine, sowing is an advantageous method of regeneration. Sowing is an advantage especially in the cases where natural regeneration is uncertain and slow.

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  • Kallio, ORCID ID:E-mail:
article id 7110, category Article
Kullervo Kuusela. (1959). Suurin kestävä hakkuusuunnite ja sen metsätaloudellinen merkitys. Acta Forestalia Fennica vol. 71 no. 1 article id 7110. https://doi.org/10.14214/aff.7110
English title: Largest permanent allowable cut and a method for its calculation.

The purpose of the investigation was to study the factors which determine the amount of the largest permanent allowable cut and to work out a method to estimate it. There is a need to have a ’short cut’ formula for rough preliminary estimates. The preliminary estimates will be checked by stock development forecasts. The largest allowable cut and its sustained basis are only guaranteed by a forecast through a period during which all the present tree stands have reached maturity and exploited.

Estimations of the largest permanent allowable cut are based on the data of the present and desirable growing stock. The present stock was a growing stock of Scots pine (Pinus sylvestris L.) dominated stands on Vaccinium type forests in Southern Finland. The connected Austrian formula is a simple way for preliminary estimation of the largest cut but its sustained basis must be checked by a stock development forecast.

In a stock development forecast the future increment and cut are calculated. For this purpose, the average site quality, tree species, age class and average volume in each class seem to be sufficient variables. The forecast is carried out within the limiting data of the present and desirable stock.

If there is an abundance of mature and over-mature stands, the largest permanent allowable cut is greater than the present increment, provided, however, that bulk of the cut is drawn by determined generation measures. Measured in solid cubic meters, the sustained cut from the Southern Finnish pine stock exceeds the present increment by 11%. With regard to the sustained saw timber production the cut can exceed the present increment by 5–7%.

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  • Kuusela, ORCID ID:E-mail:
article id 7486, category Article
Paavo Yli-Vakkuri. (1959). Siemensiipien hankaajista ja niiden vaikutuksesta siemenen itävyyteen. Acta Forestalia Fennica vol. 68 no. 4 article id 7486. https://doi.org/10.14214/aff.7486
English title: On machines for abrading seed wings and their influence on the germinative capacity of the seed.

This paper deals with two machines designed for abrading seed wings, and their influence on the germinative capacity of seed of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.). Both machines are commonly used in Finland.

The results of the study indicate that the act of abrading may cause slight or even serious injuries to the seed. Slight injuries of about 3% are probably not easily avoided if mechanical abrading is resorted to. It must be noted, however, that even this reduction in germinative capacity causes significant yearly loss. If the reduction in germinative capacity is greater, which seems to be possible, it is advisable to test the mechanism of the machine and its method of abrading. As the clearance of the machines can affect the extent of injuries, all machines should be tested. If possible, a continual operation control should be arranged. It could, at the same time, to supply material for improving the abrading method and equipment.

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  • Yli-Vakkuri, ORCID ID:E-mail:
article id 7478, category Article
Paavo Yli-Vakkuri. (1958). Tutkimuksia ojitettujen turvemaiden kulotuksesta. Acta Forestalia Fennica vol. 67 no. 4 article id 7478. https://doi.org/10.14214/aff.7478
English title: Studies on prescribed burning of drained peatlands.

Prescribed burning has been used to treat the mineral soil sites, but the method has been little used in drained peatlands. The course and methods of prescribed burning in drained peatlands, and the effect of burning on sprouting of broadleaved trees, growth of ground vegetation and regeneration of Scots pine (Pinus sylvestris L.) by sowing was studied in drained pine bogs in Southern Finland. The top layer of the peat was mostly Sphagnum peat. The material included a prescribed burned 12 ha drained peatland area in Tuomarniemi district, in addition to which ten previously burned areas were investigated.

The burning had succeeded mostly well, but also unsuccessfully burned sites were observed. Estinguishing of the fire was easy, and no peat fires occurred. The fire burned only the logging residue, ground vegetation and the dry top layer of the peat. The roots of brushwood and grasses survived in the peat that insulated the top layer from the heat. For instance, the abundance of cloudberry (Rubus chamaemorus L.) increased after the fire. Similarly, burning did not affect sprouting of the stumps of downy birch (Betula pubescens Ehrh.). It cannot thus be used as a method to restrict the growth of coppice in regenerated areas. The seeds of Scots pine germinated well on the burned surface. 46% of the seeds developed to seedlings on sphagnum-shrub vegetation and 16% in feathermoss-shrub vegetation.

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  • Yli-Vakkuri, ORCID ID:E-mail:
article id 7476, category Article
Leo Heikurainen. (1958). Sekametsiköiden juuristoista ojitetulla suolla. Acta Forestalia Fennica vol. 67 no. 2 article id 7476. https://doi.org/10.14214/aff.7476
English title: Root systems of mixed forest in drained peatlands.

Draining transforms root systems of trees growing in peatlands towards the ones growing on mineral soil. However, even after efficient draining the root systems differ from the root systems of trees growing on mineral soil. This investigation concentrates on root systems of forests of similar mire types growing in similar draining conditions but having different tree species compositions. The peatland, situated in Pieksämäki in Southern Finland, was drained in 1937. Sample plots, measured in 1956, consisted of mixed forest of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L. Karst.) and birch (Betula sp.) in different compositions, and were in natural condition.

The sedge pine bog studied in this investigation was shown to have larger total amount of roots and mycorrhiza than in previously studied dwarf shrub pine bogs. This reflects better growth conditions of the better site. The depth of root system was, however, similar. Root systems of birch were deeper than those of the coniferous tree species. Differences between Scots pine and Norway spruce were small. Corresponding differences between the species were found in the density and total number of mycorrhizas. The abundance of mycorrhizas in the roots of birch increased in deeper layers of peat, but decreased especially in spruce roots. In earlier studies the abundance of mycorrhizas decreased in the roots growing in deeper layers in pure Scots pine stands, but no such variation was seen in this study. The result suggest that the deep root system of birch may affect also the root systems of the coniferous trees. On the other hand, birch roots can have advantage over the coniferous trees.

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  • Heikurainen, ORCID ID:E-mail:
article id 7475, category Article
Peitsa Mikola. (1958). Liberation of nitrogen from alder leaf litter. Acta Forestalia Fennica vol. 67 no. 1 article id 7475. https://doi.org/10.14214/aff.7475

Litters of different plant species vary greatly in regard to their nutrient content and other properties. The aim of the study was to compare different litters from the standpoint of their value as soil fertilizer. In an experiment Scots pine (Pinus sylvestris L.) seedlings were grown in pot cultures in which known amounts of different litters had been mixed with the soil. The tested litters were Pinus sylvestris (L.), Larix sibirica (Ledeb.), Betula sp., Populus tremula (L.), Alnus incana (L.) Moench, A. glutinosa (L.) (Gaertn.), Sorbus aucuparia (L.), Tilia cordata (Mill.), Acer platanoides (L.), Corylus avellana (L.), Eupteris aquilina (L.), and Deschampsia flexuosa (L.) Trin.

A striking difference was found between alder (Alnus sp.) leaf litter and all the other litters tested. The difference can be seen from the second growth season on, becaus the young seedling uses mainly the nutrients included in the seed. The leaf litter has mainly unfavourable effect on the growth of the pine seedlings. Only both alder species improve the growth. This is mainly due to the nitrogen content of alder leaves. Tree leaves and other forest litter are often composted in the forest nurseries. It seems that adding nitrogen to the compost is necessary, otherwise compost added to the soil may have a harmful effect on the seedlings. Alder, on the other hand, has nitrogen binding Actinomyces growing in symbiosis in its root nodules, and is able to utilize atmospheric nitrogen.

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  • Mikola, ORCID ID:E-mail:
article id 7472, category Article
Jaakko Lehto. (1956). Tutkimuksia männyn luontaisesta uudistumisesta Etelä-Suomen kangasmailla. Acta Forestalia Fennica vol. 66 no. 2 article id 7472. https://doi.org/10.14214/aff.7472
English title: Studies on the natural regeneration of Scots pine on the upland soils of Southern Finland.

Natural regeneration of Scots pine (Pinus sylvestris L.) by leaving a seed tree stand on a cutting area has long been the most popular regeneration method in Finland. Results of the method have, however, been unsatisfactory. The aim of the investigation was to study the basic problems of natural regeneration of Scots pine. Regeneration success was studied in 144 sample plots in pine stands at different stages of regeneration in Southern Finland. In addition, the data included information of 42 previously investigated areas.

According to the results, Scots pine can be successfully regenerated naturally on sandy and gravelly soils in Southern Finland. Preparing the ground surface by breaking or burning considerably facilitates the establishment of a seedling stand. The number of seedlings was considerably lower in the ground vegetation than in the mineral soil. Considering growth of the seedlings, root competition of the mother trees was heavy in dense stands, but insignificant in thin stands. The stand density did not affect germination of the seeds. In regeneration areas proper, where the density of mother trees usually is under 50 per hectare, there was in average 4,700 seedlings per hectare in Calluna type forests and 5,200 in Vaccinium type forests.

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  • Lehto, ORCID ID:E-mail:
article id 7466, category Article
Leo Heikurainen. (1955). Rämemännikön juuriston rakenne ja kuivatuksen vaikutus siihen. Acta Forestalia Fennica vol. 65 no. 3 article id 7466. https://doi.org/10.14214/aff.7466
English title: Structure of Scots pine root systems in a pine swamp and effect of draining on the structure.
Original keywords: räme; ojitus; juuristo; mänty; mykorritsa; suo

The root system of a Scots pine (Pinus sylvestris L.) growing on a peatland is restricted, according to earlier studies, on the top layers of the peat above the groundwater level. Drainage of the peatland affects growth of the root system. This investigation aims at studying the root systems on the point of view of draining of peatlands. The structure and distribution, and the growth of mycorrhiza in Scots pine roots in pine swamps varying from natural state to well drained state is studied.

The study shows that Scots pine on pine swamps has more extensive root system than has earlier assumed, it is common to find 1,000 m of roots in one cubic meter in a healthy stand. The trees reach this density of roots early on. In a drained peatland, the total root length is markedly higher than in a similar stand in natural state. The root systems proved to be very shallow. Even in a well-drained site the roots did not grow deeper than 20 cm. 70% of all roots were found in the upper 5 cm layer of peat, and 90% in the upper 10 cm layer. Root systems were deeper in drained peatlands, but the difference was small. In a site in natural state the average depth of the roots was 4 cm, and in a drained site 5 cm. About 85% of the roots were under 1 mm of diameter. Short roots were found only in the fine roots. Draining increases strongly the number of short roots. Mycorrhizas of the types A, B, C and D as well as pseudomychorrizas were found in the pine roots.

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  • Heikurainen, ORCID ID:E-mail:
article id 7440, category Article
Erkki K. Kalela. (1954). Mäntysiemenpuiden ja -puustojen juurisuhteista. Acta Forestalia Fennica vol. 61 no. 28 article id 7440. https://doi.org/10.14214/aff.7440
English title: Root systems of Scots pine seed trees and stands.

Root systems of a Scots pine (Pinus sylvestris L.) stands of seed trees on a Vaccinium sites in Southern Finland were studied by taking soil samples around the seed trees. The results show that root system of an old Scots pine spreads relatively evenly around the tree up to at least 10 meters from the stem. The densest part of the root system is near the stem, which part is often acentric. This is probably due to root competition in the early stages of growth of the tree.

Root systems of the seed trees affect stocking of the site with seedlings and the growth of the seedlings. The root competition can cause, for instance, uneven grouping of the seedlings. It seems that the largest trees of a stand have the most even root system. It is therefore recommended to choose the strongest trees of the stand as seed trees, to ensure even distribution of seedlings.

The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.

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  • Kalela, ORCID ID:E-mail:
article id 7439, category Article
Leo Heikurainen. (1954). Rämemänniköiden uudistamisesta paljaaksihakkausta käyttäen. Acta Forestalia Fennica vol. 61 no. 27 article id 7439. https://doi.org/10.14214/aff.7439
English title: Regeneration of Scots pine stands of pine swamps through clear cutting.

Pine swamps are easily regenerated by natural regeneration of Scots pine (Pinus sylvestris L.). Usually seeding felling is used, but also strip system or clear cutting and regeneration along stand edge has been suggested. This article discusses the regeneration by clear cutting and sparing the existing undergrowth. The article focuses on pine swamps to be drained and the ones in natural state.

Pine swamps in natural state usually have plenty of trees of smaller diameter classes, that can be trusted to form the future tree generation after the felling. This shortens the rotation by 20-30 years. The undergrowth has been shown to recover quickly. The method suits for regeneration of drained peatlands but could fit also for regeneration of pine swamps in natural state.

The seedlings in the pine swamps are mainly 1-5 years old, and the stock is changing. It seems that larger trees produce a wider selection of age groups, but the seedlings survive longer under smaller mother trees. Part of the younger generations of seedlings seem to be destroyed when the peatland is drained. Further studies are needed to investigate how the draining and felling are to be performed to spare the young seedlings.

The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.

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  • Heikurainen, ORCID ID:E-mail:
article id 7432, category Article
Ukko Rummukainen. (1954). Männyn ja kuusen käpysadosta ja sen arvioinnista vuosina 1950-1953. Acta Forestalia Fennica vol. 61 no. 20 article id 7432. https://doi.org/10.14214/aff.7432
English title: Estimation of Scots pine and Norway spruce cone crop in 1950-1953.

The cone crop of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) has been assessed in Finland since 1930 annually by sending a questionnaire to forest professionals around the country. Based on the result it is decided if the crop is good enough for collection of the cones next winter. This article presents the results of cone surveys in 1950-1953, and suggest improvements in the method of the investigation.

According to the survey, Scots pine crop was best in 1952, when the crop was intermediate in the whole country, and relatively abundant in the county of Lapland. Norway spruce crop was best in 1951, when the crop was better than in average in the whole country. The evaluators had variable opinions whether the crop was good enough for cone collection or not. They assessed the pine cone collection more often as profitable than the spruce cone collection. Usual reasons to regard spruce cone collection as unprofitable were seed damages and the sites being too far away. To make the results more uniform and accurate, a suggestion to change the evaluation method is presented. The evaluation should be focused on the cone crop of mature stands.

The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.
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  • Rummukainen, ORCID ID:E-mail:
article id 7411, category Article
Aarne Nyyssönen. (1954). Hakkauksilla käsiteltyjen männiköiden rakenteesta ja kehityksestä. Acta Forestalia Fennica vol. 60 no. 4 article id 7411. https://doi.org/10.14214/aff.7411
English title: Structure and development of Scots pine stands treated with different cuttings.

Permanent sample plots are considered to be the most reliable basis for investigations into structure and development of stands. Such sample plots, established since 1924 in Finland, have been used to study thinnings of varying intensity. These studies are yet too short to give comprehensive conclusions. It is also possible to base the studies on sample plots measured in managed forests and gain in this way information suitable for practical purposes. In this investigation development of stands treated by two different methods, repeated thinnings and repeated selection cutting were studied in pure, even-aged Scots pine (Pinus sylvestris L.) stands in Southern Finland, on three forest types.

The results show that volume increment level of naturally normal stands seem to have been reached easily by stands treated with repeated thinnings. With advancing age, the growing stock of thinned stands fall short from the natural stands. As thinnings have removed primarily the poorest trees, the increment is distributed over trees of a larger size more in thinned than in naturally normal stands.

When intensive cuttings have resulted in a relatively small growing stock, the decrease in volume increment leads to considerable decrease in volume. The size of the tree has no essential effect – within certain limits - on the volume increment of the stand, if the volume removed is similar. However, every intermediate thinning removing largest-sized trees may result in the prolonged rotation. Since the volume increment of an older stand is much smaller than earlier, intermediate thinnings removing largest-sized trees should be avoided if the aim is the greatest volume yield. The growing stock of middle-aged or older stands untreated or treated with slight cuttings only can as a rule be considerably reduced without volume increment declining.

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  • Nyyssönen, ORCID ID:E-mail:
article id 7410, category Article
Paavo Yli-Vakkuri. (1953). Tutkimuksia puiden välisistä elimellisistä juuriyhteyksistä männiköissä. Acta Forestalia Fennica vol. 60 no. 3 article id 7410. https://doi.org/10.14214/aff.7410
English title: Studies on physical root connections between the trees in Scots pine stands in Finland.

Observations of connections between the roots of living trees and root systems of stumps have been reported already in 1900s. In Finland root connections have been found in Birch (Betula sp.), Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.), but there are no studies on abundance of the connections. This investigation studied root connections in a series of naturally regenerated Scots pine stands from seedling stands to mature trees in Southern Finland, and some sown seedling stands.

Root connections were found to be common in naturally regenerated, older stands that had passed the thicket stage. Approximately 21-28% of the trees had at least one root connection to another living tree, dead tree or living stump. Connections were few or absent in seedling stands. Sown seedling groups had many root connections in contrary to naturally regenerated seedling stands. Trees belonging to the dominating canopy class had most root connections. The trees could form a network of up to twenty trees and living stumps. Root connections were more common the larger the tree was or the nearer the trees grew each other. The coalescent roots were often situated near the stem. Experiments showed that water and nutrients transferred in the roots could move from one tree to another. Living stumps from previous fellings were relatively common. In the sites studied, there was in average 178 stumps connected to a living tree per hectare.

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  • Yli-Vakkuri, ORCID ID:E-mail:
article id 7407, category Article
Olli Vaartaja. (1951). Alikasvosasemasta vapautettujen männyn taimistojen toipumisesta ja merkityksestä metsänhoidossa. Acta Forestalia Fennica vol. 59 no. 3 article id 7407. https://doi.org/10.14214/aff.7407
English title: On the recovery of released Scots pine undergrowth and its silvicultural importance.

There are contrary opinions on the ability of Scots pine (Pinus sylvestris L.) seedlings to withstand oppression by hold-overs and recover after their felling. The recovery potential of oppressed pine stands in Southern and Northern Finland was studied using two kinds of material, fully recovered Scots pine stands and stands recently released. The volume and volume increment of the stand were measured, and the health of the sample trees was determined.

The study showed that those released pine stands that had been in oppressed state very long (25-60 years) had recovered after clear-cutting. After the release the stands grew at first slowly, but after recovery at about the same rate as natural normal stands of a similar height. The smaller, younger, and less stunted the seedlings were when they were released, and the better the site, the faster was the recovery. At the base of released pine stands various defects was detected. When the trees were released, the defects decrease their technical value. A heavy partial cutting had generally a disadvantageous effect on the stand. Recovering seedlings were found clearly to hinder the development of younger seedlings nearby. This inhibition seemed to be a result of the rapid spread of the root system of released pine trees.

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  • Vaartaja, ORCID ID:E-mail:
article id 7406, category Article
Jaakko O. Murto. (1951). Mäntypuumme pihka voiteluöljyn raaka-aineena : puunkäyttöopillinen tutkimus. Acta Forestalia Fennica vol. 59 no. 2 article id 7406. https://doi.org/10.14214/aff.7406
English title: Finnish Scots pine resin as raw material for lubricating oil.

After the Second World War shortage of lubrication oil forced Finland to develop a substitute product that was produced of indigenous materials. This report is an overview of the history of the already terminated lubricating oil industry and it gives a detailed description of lubricating oil production.

The annual lubricating oil consumption in Finland was 15,000 tons before the war, but during the war it decreased to 7-8,000 tons. In 1943 Oy Tervaöljy Ab (Tar Oil Limited) was established with the state of Finland as the main shareholder. It was commissioned to plan and build tar and tar oil plants, and it also transmitted tar from stump wood pyrolyzing plants to oil factories. Two raw materials were used to produce tar oil: tar wood collected from Scots pine (Pinus sylvestris L.) stumps and tall oil, a by-product of sulphate pulp mills. A total of 9,000 tons of lubricating oil substitutes was produced in 1943-1947, 53% of this from sulphate pulp mill by-products and 47% from tar and shale oil.

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  • Murto, ORCID ID:E-mail:
article id 7398, category Article
Erkki K. Kalela. (1949). Männiköiden ja kuusikoiden juurisuhteista I. Acta Forestalia Fennica vol. 57 no. 2 article id 7398. https://doi.org/10.14214/aff.7398
English title: On the horizontal roots in Scots pine and Norway spruce stands.

The purpose of the investigation was to study the amount, quality and distribution by layers of depth of horizontal roots in Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) stands in Southern Finland. The sample plots included stands on soil varying from sandy to stony, and stands of  varying ages from seedling stands to an old stand, in Myrtillus and Vaccinium type forests.

In a Norway spruce stand, the amount of roots increases rapidly and reaches its maximum, about 450 meters/m3, at an age of 100-110 years. In a Scots pine stand the maximum, about 370 m/m3, is reached earlier, at an age of 60-70 years. The root system of pine expands more rapidly than that of spruce. The total length of the horizontal root system of pine amounts to 1,000 m soon after 40 years of growth, of spruce at the age of 60. Later the situation changes, and at the age of 110 the root systems of both species are about the same size, but older trees of spruce have more extensive root system.

Majority of horizontal roots are under 1 mm in diameter. Of the horizontal roots of spruce stands the majority lie in the humus layer and in the topmost mineral soil stratum. Over half of horizontal spruce roots are, thus, at a maximum depth of 5 cm, while majority of the roots of Scots pine lie at maximum in depth of 10 cm. At the same layer grow also the roots of the ground vegetation, which may affect the competition between the species.

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  • Kalela, ORCID ID:E-mail:
article id 7381, category Article
Erkki K. Kalela. (1946). Pihkomiskokeita pohjoisissa männiköissä. Acta Forestalia Fennica vol. 52 no. 3 article id 7381. https://doi.org/10.14214/aff.7381
English title: Collection of resin in Scots pine forests in the Nordic countries.
Original keywords: pihka; pihkan keräys; pihkominen; mänty

Systematic resin collection has not been practiced in Finland or other Nordic areas. One reason is the short growing season. Also, the local pine species, Scots pine (Pinus sylvestris L.) gives smaller resin yield than the southern species, such as Pinus maritima. In Nordic boreal forests resin has been collected only in the Soviet Union, where it has been practised also in Eastern Karelia, near the Finnish border. Resin collection experiments were arranged in former resin collection stands in Karelia in 1943. A so-called German method for running resin had been used in the stands. 30-40 sample trees were chosen in five sample sites.

Forest type did not have big influence in the resin yield. The yield seemed to be slightly higher in Scots pine stands growing in fertile sites compared to poorer sites. The diameter of the tree had largest effect on the yield. It is recommended to focus on stands with large trees, and trees with a large, vital crown. In this kind of stands it is possible to get best yield in relation to the work required. The height of the patch that was cut in the stem had no influence on the yield. The size of the patch should, however, not exceed 35-50% of the diameter of the tree.

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  • Kalela, ORCID ID:E-mail:
article id 7367, category Article
Esko Kangas. (1942). Karistuslämmön vaikutuksesta männyn siemenen karisemiseen ja itämiseen. Acta Forestalia Fennica vol. 50 no. 14 article id 7367. https://doi.org/10.14214/aff.7367
English title: Effect of seed extracting temperature on extraction and germination of Scots pine seeds.

Temperatures needed in extracting Scots pine (Pinus sylvestris L.) seeds is relatively high, however, there is little information on its effect on germination of the seeds. This survey aimed at studying how different temperatures affect both extraction result and germination of Scots pine seeds. Comparisons between different temperatures (20, 30, 40, 50, 60 and 70 ºC) were made from cones collected from same sample trees, three trees in total.

Temperatures 20 and 30 ºC resulted in incomplete opening of the cones, and gave thus smaller amount of seeds. Complete extraction requires at the least the temperature of 40 ºC. The result is slightly better in 50 ºC, but germination of the seeds is little lower. Temperatures 60 and 70 ºC improve the results, but in the cost of germination. The main reason for lower germination percentage was that the higher temperatures release more empty and defective seeds from the cones. Results of different sample trees were different due to, for instance, quality and size of cones. Higher temperatures accelerated the extraction. According to the study, perfect extraction in 40 ºC requires longer extraction time than when the temperature of 50 ºC is used. In practice, 50 ºC temperature or even little higher temperatures can be used when the extraction time is shorter. Decessive factors in choosing the temperature would be the humidity of cones and length of extraction time.

The PDF includes a summary in German.

  • Kangas, ORCID ID:E-mail:
article id 7361, category Article
M. Lappi-Seppälä. (1942). Siperian lehtikuusen kasvusta sekametsiköissä Evon valtionpuistossa. Acta Forestalia Fennica vol. 50 no. 8 article id 7361. https://doi.org/10.14214/aff.7361
English title: Growth of Siberian larch in mixed stands in state forests of Evo in Finland.

Of the foreign tree species Siberian larch (Larix sibirica Ledeb.) has the biggest economical potential in Finland. In its natural distribution the species grows mostly in mixed stands in other areas than the core of its range in Siberia, where it grows also in pure stands. However, growth studies have given contradictory results about how Siberian larch can manage competition of different tree species in mixed stands. In this study two-year old Siberian larch seedlings were planted in areas previously sown with Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). The growth of the trees was measured when the stands were 50 years old.

It appears that the stands, about 3700 larch seedlings per hectare, have originally been too been too dense. In the two thinnings done in the area, larch has probably been favoured, which has resulted in varying mix of pine and spruce. In the 50-year old stands, Siberian larch has developed faster than Scots pine and Norway spruce. Contrary to some previous studies, the results show that Siberian larch can be grown also in mixed stands, but the growth will probably be slower than in pure stands. Best growth is achieved in pure stands that have been planted thinly enough.

The PDF includes a summary in German.

  • Lappi-Seppälä, ORCID ID:E-mail:
article id 7359, category Article
V. T. Aaltonen. (1942). Muutamia kasvukokeita puuntaimilla. Acta Forestalia Fennica vol. 50 no. 6 article id 7359. https://doi.org/10.14214/aff.7359
English title: Growth studies on tree seedlings.

The aim of the study was to investigate effect of growth conditions on germination and growth of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings in greenhouse conditions. Germination of seeds becomes markedly slower as the soil temperature decreases. It seems that low temperatures affect more Norway spruce than Scots pine. When temperature rises, the fresh weight of the seedlings increases more in pine seedlings than in spruce seedlings. Accordingly, lower temperatures affect less the weight growth of spruce seedling than that of pine seedlings.

An experiment testing how root competition affect germination showed that adjacent seedlings decrease germination of seeds more than shading with branches. The effect was strongest on pine and spruce seedlings when the shading tree species was fast growing birch (Betula sp.). On the other hand, shading affected most height growth of birch seedlings. Growing space can vary in relatively large range without it affecting greatly tree growth.

The PDF includes a summary in German.

  • Aaltonen, ORCID ID:E-mail:
article id 7354, category Article
P. S. Tikka. (1940). Puiden vikanaisuuksien merkitys ja huomioon ottaminen Perä-Pohjolan mäntymetsien hoidossa. Acta Forestalia Fennica vol. 50 no. 1 article id 7354. https://doi.org/10.14214/aff.7354
English title: The effect of injuries in trees on forest management of Scots pine stands in Northern Finland.

The aim of the study was to find out what are the causes of damage in Scots pine (Pinus sylvestris L.) stands and the frequency of different kinds of injuries, which are then discussed in relation to the silvicultural state and management of the stands in comparison to ideal forests. Sample plots were studied in over 80-year old Scots pine dominated stands in mineral soil sites of different forest types in Northern Finland in the area of Perä-Pohjola. 10–40 trees were chosen as sample trees in each sample plot. The sample trees were felled, and the diameter, height of crown and injuries outside and inside of the stem were recorded.

Length of knot-free part of the stem was higher in the dominant trees and in older age classes of the trees. The form of the stem becomes broader and rounder with the age. The crowns are, however, longer in Northern Finland compared to Southern Finland. In management of Scots pine stands, all trees diseased by Scots pine blister rust (Cronartium flaccidum) should be removed. The disease is common in Northern Finland, and the number of diseased trees increases as the stands get older. Decay was more common in trees that had fire wounds. In general, injuries decreased the length and diameter growth of the trees. From the dominant trees should only injured and diseased trees removed in the thinnigs. Codominant trees can be left to grow when spare trees are needed to replace missing dominant trees. Detailed instruction of selection of the removed trees are given for each age class.

The PDF includes a summary in German.

  • Tikka, ORCID ID:E-mail:
article id 7351, category Article
Esko Kangas. (1940). Tuloksia Pohjankankaan ja Hämeenkankaan metsänviljelyksistä. Acta Forestalia Fennica vol. 49 no. 4 article id 7351. https://doi.org/10.14214/aff.7351
English title: Studies on artificial regeneration in Pohjankangas and Hämeenkangas in Southern Finland.

The regeneration of forests in Hämeenkangas area in Southern Finland has been difficult due to various damages from the middle of the 1800s. Few seed trees were left in the area, and artificial regeneration has been used since 1880s. The area became an experimental area of the Forest Research Institute in 1924. The aim of the study was to survey the area before it was transferred to the Finnish Defense Forces.

The original Scots pine (Pinus sylvestris L.) forest of the esker area suffered from many forest fires. The total area is 13,000-14,000 ha, of which the experimental forests of Forest Research Institute cover 6,000 ha. The area is dry upland forest, and drought affects the survival of germlings. Soil frost is a major cause of loss of young seedlings. Sowing method affects the early development of the seedlings. Band sowing proved to be the best method regarding the soil frost. A total of 39 different harmful insect species, 8 pathogen species and 7 other causes of damages have been detected in the area.

The development of seedling stands follow a certain pattern, reported also in other studies. Many of the pine seedling stands develop well until they reach a certain height. After that seedlings begin to suffer from damages, but after reaching another stage develop normally. The damages affect the height growth of the seedlings. Some common damages are caused by Pissoides weevils, needle damages caused by certain beetles, shoot damages by Evetria resinella, and pine blister rust (Peridermium pini and Cronartium flaccidum).

The PDF includes a summary in German
  • Kangas, ORCID ID:E-mail:
article id 7336, category Article
R. Sarvas. (1937). Kuloalojen luontaisesta metsittymisestä : Pohjois-Suomen kuivilla kankailla suoritettu metsäbiologinen tutkielma. Acta Forestalia Fennica vol. 46 no. 1 article id 7336. https://doi.org/10.14214/aff.7336
English title: Natural regeneration of burned areas. Forest biological study in dry mineral soil sites in Northern Finland.

Natural regeneration has been common in Northern Finland, where forest fires have been usual, and the large areas make artificial regeneration expensive. The regeneration, and for instance tree species composition and density of the stand, cannot been controlled. In Northern Finland there is little demand for Betula sp. which is often abundant in the burnt areas. The unburned forests are generally Scots pine (Pinus sylvestris L.) or Norway spruce (Picea abies (L.) H. Karst.) dominated mixed forests with single Betula sp. trees.

The fire destroys birch for the most part in the Vaccinium site type, but the surviving trees produce enough seeds to regenerate the areas. The largest trees of Scots pine usually survive the fires. Pine has good seed years in the north only every 8th or 10th year. Spruce is totally destroyed in the forest fire and the seedlings grow poorly as primary species. The seedling stands are usually dominated by Scots pine and birch, but birch seedlings grow in batches, and do not hinder growth of pine. The drier Calluna site type stands are dominated by Scots pine. Birch seedlings may be abundant in the beginning, but most of them do not survive. Abundant emergent pine trees prevent the growth of seedlings especially in the dry site types, and they should be thinned to guarantee regeneration. Sowing results are better few years after the fire. The birch seedling should be removed from the seedling stands.

The PDF includes a summary in German.

  • Sarvas, ORCID ID:E-mail:
article id 7325, category Article
V. T. Aaltonen. (1936). Kuusi männyn kilpailijana kasvupaikasta. Acta Forestalia Fennica vol. 42 no. 8 article id 7325. https://doi.org/10.14214/aff.7325
English title: Norway spruce as competitor in the sites typical for Scots pine.

Norway spruce (Picea abies (L.) H. Karst.) is a species that becomes in Finland over time the dominant species in the sites that are suitable for it. The reason that it covers only a quarter of the forest areas in Finland depends mainly on forest fires. The aim of this review was to discuss the biological factors that affect competition between Scots pine and Norway spruce.

Especially important is the ability to regenerate and grow past seedling stage. There does not seem to be significant differences in the number of good seed and seedling years of the species. Spruce regenerates better on moss covered forest floor than pine. On the other hand, pine seedlings grow faster than spruce seedlings, and tolerate better dry conditions. Consequently, one of the defining biological differences is that Norway spruce needs more humid conditions than Scots pine. Spruce is shown to have greater transpiration than pine. Spruce also has higher site requirements, however, growing as undergrowth, it seems to be better able to compete of the nutrients with the larger trees than pine. It also tolerates shading better. Spruce is less frost tolerant than pine.

The PDF includes a summary in German.

  • Aaltonen, ORCID ID:E-mail:
article id 7313, category Article
Erkki Laitakari. (1934). Männyn kääpiöversojen ja kasvainten välisistä suhteista. Acta Forestalia Fennica vol. 40 no. 36 article id 7313. https://doi.org/10.14214/aff.7313
English title: The relations between main and short shoots of Scots pine.
English keywords: needle; short shoot

The number of short shoots and the quality of the shoots and needles in 19 shoots of 15 Scots pine (Pinus sylvestris L.) was measured. Usually Scots pine short shoots have two needles. Three-needle short shoots were found in all sample shoots but one. They were most common in fast-growing trees and the shoots in the main stem. One-needle short shoots were relatively rare. In most cases the second needle had withered. The length of the needles was 19‒80 mm, and most common lengths were 30‒50 mm. The width of the needles was in average 0.5‒1.94 mm. There was correlation between the length of the shoot and the length of the needles.

The PDF includes a summary in German.

  • Laitakari, ORCID ID:E-mail:
article id 7297, category Article
A. L. Backman. (1934). Om den Åländska skogens förhistoria. Acta Forestalia Fennica vol. 40 no. 20 article id 7297. https://doi.org/10.14214/aff.7297
English title: Early history of forests in Åland, Finland.

The paper presents preliminary results of paleobotanical studies on vegetation in Åland, south-west Finland. The investigations concentrated on studying arrival of tree species and stratigraphy of peatlands. According to the studies, some plant fossils found in the peat (Ceratophyllum submersum, Sparagnium neglectum, Najas flexilis) indicate that climate of the region has earlier been warmer than at the present. The present forests in Åland are dominated by coniferous species, but the pollen analysis of the peat indicate that Norway spruce (Picea abies (L.) H. Karst.) became a common species in the region about by the time of Christ’s birth. The species has reached its present distribution in Åland relatively late. The pollen analyses give relatively little information about the arrival of birch (Betula sp.) and Scots pine (Pinus sylvestris L.), but it seems obvious that occurrence of birch reached its culmination just before spruce. During the warm period common alder (Alnus glutinosa (L.) Gaertn.) was the most important species, and also pollen of oak (Quercus robur L.), kinden (Tilia cordata L.) and elm (Ulmus sp.) was relatively common in the peat of some of the studied peatlands. An interesting finding was the pollen of Carpinus betulus in many sites in Åland.

The PDF includes a Finnish and German summary.

  • Backman, ORCID ID:E-mail:
article id 7287, category Article
Erkki K. Cajander. (1934). Havaintoja eräällä myrskytuhoalueella. Acta Forestalia Fennica vol. 40 no. 10 article id 7287. https://doi.org/10.14214/aff.7287
English title: Observations in a storm damage area.

A big storm hit Finland in 12.10.1933, and caused forest damages especially in the coasts of the Gulf of Finland and Baltic Sea, and in the eastern part of the country. In these areas the wind felled about 75,000‒85,000 m3 timber trees in the state lands. The extent of the wind damage was measured in forest area of 1,500 hectares in Lapinjärvi in Southern Finland. The wind had felled 42% of the Scots pine (Pinus sylvestris L.), 70% of the Norway spruce (Picea abies (L.) H. Karst.) and 44% of the Betula sp. trees. Thus, Norway spruce had been most susceptible for wind damage. That extensive damages in Norway spruce seed tree stands risk the regeneration in the area. Natural regeneration of Norway spruce using seed trees may, therefore, be questioned. The seed tree areas on hills, and especially hollows next to the hills were susceptible for wind damage. A denser border stand protects sparsely stocked seed tree area. The damages were also smaller in older seed tree areas, where the trees and ground vegetation had had time to recover after the felling. The felled spruce and birch trees had often stem rot.

The PDF includes a summary in German.

  • Cajander, ORCID ID:E-mail:
article id 7286, category Article
Matti Jalava. (1934). Havaintoja puun aseman vaikutuksesta puun ominaisuuksiin. Acta Forestalia Fennica vol. 40 no. 9 article id 7286. https://doi.org/10.14214/aff.7286
English title: Influence of the position of a tree in the stand upon the properties of the wood.

The growth of a tree is influenced by inherited properties and external circumstances, including climate, soil, the position of the tree in the stand, and the position of the wood in the stem. The tree species have optimum climate and optimum conditions. The aim of this study was to determine if the summerwood content of the wood of Scots pine (Pinus sylvestris L.) is dependent on the rate of growth of the tree. Comparing the position of the sample trees in the stand, it seems that the position of the tree and the size of its crown influences strongly the quality of the wood. In a dense stand the summerwood content was higher in the trees that had small crowns. Thinning of the stand decreased the difference in summerwood content of the trees.

The PDF includes a summary in English.

  • Jalava, ORCID ID:E-mail:
article id 7273, category Article
T. J. Hintikka. (1933). Muutamia havaintoja männyn tuulenpesistä. Acta Forestalia Fennica vol. 39 no. 2 article id 7273. https://doi.org/10.14214/aff.7273
English title: Observations on witches' brooms in Scots pine.
English keywords: witches' broom; mutation

Witches' brooms of Scots pine (Pinus sylvestris L.) have been suggested to be genetic rather than caused by bacteria. Seeds were collected from cones growing in Scots pine witches' brooms. More than half (43) of the 84 seedlings grown from the seeds were stunted and resembled witches' broom. The growth of the normal and witches' broom like seedlings were compared. When the seedlings were 8 years old, the normal seedlings were in average 37 cm and the witches' broom like seedlings 8 cm high. The result supports the theory that the witches' broom like growth was inherited in the Scots pine seedlings.

The PDF includes a summary in German.

  • Hintikka, ORCID ID:E-mail:
article id 7259, category Article
I. Lassila. (1929). Metsätyypin vaikutuksesta puun painoon. Acta Forestalia Fennica vol. 36 no. 1 article id 7259. https://doi.org/10.14214/aff.7259
English title: The influence of forest site type on the weight of wood.

Earlier research has presented contradictory results of the influence of forest site type on the weight of wood. In this study, dominant trees of Scots pine (Pinus sylvestris L.) was chosen as sample trees on four forest site types: Calluna, Vaccinium, Myrtillus and Oxalis site types. The trees were felled in autumn, when the water content of the wood is low. Weight of the test samples was measured weigh before and after drying. Undried wood, both sapwood and heartwood, is heavier in Myrtillus type than in Vaccinium type. The weight of the air-dried heartwood did not differ between the two forest site types. Air-dried- sapwood was heaviest in Myrtillus site type. Air-dried heartwood was heaviest in Vaccinium site type, and lightest in Oxalis type. Owen-dried sapwood was heaviest in Calluna site type, where the tree growth is slow, but weight differences were small in owen-dried heartwood. It can be claimed that forest type affects wood quality.

The PDF includes a summary in English.

  • Lassila, ORCID ID:E-mail:
article id 7231, category Article
Martti Hertz. (1929). Huomioita männyn ja kuusen pituuskehityksen "vuotuisesta" ja vuorokautisesta jaksosta. Acta Forestalia Fennica vol. 34 no. 18 article id 7231. https://doi.org/10.14214/aff.7231
English title: Observations on annual and daily cycles in the height growth of Scots pine and Norway spruce.

The height growth of Scots pine (Pinus sylvestris L.) seedlings were observed in Korkeakoski and Evo in Southern Finland in 1925-1928. The growth was slow in the beginning of the growing season, increased after that to decrease again towards the end of the growing season. The height growth begun in May, reached the fastest growth rates in June, and ended in June-July. According to the earlier studies, the length of the height growth of Scots pine is dependent on the temperature of the previous summer. This study showed that warm temperatures of the same summer promote height growth, and low temperatures slow it down. Also the daily growth fluctuates, being highest during the afternoon and slowest during the early morning. The daily growth is dependent on temperature.

Norway spruce (Picea abies (L.) H. Karst.) begin the height growth in average 9 days later than Scots pine. Compared to pine, the speed of growth in spruce decreases slower towards the late summer.

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander. The PDF includes a summary in German.

  • Hertz, ORCID ID:E-mail:
article id 7219, category Article
W. E. A. Hiley. (1929). A financial analysis of a money yield table. Acta Forestalia Fennica vol. 34 no. 6 article id 7219. https://doi.org/10.14214/aff.7219

The aim of the study was to compare the theories of Soil Rental and Forest Rental. There is a controversy between the theories that is associated to the issues of length of rotation and grade of thinning. For the basis of the analysis was chosen Schwappach’s money yield table for Scots pine (Pinus sylvestris L.) Quality II, published in 1908. Based on the table was calculated the financial yield, the net annual income from a normal forest managed on various rotations, the capital value, and the net income expressed as the rate of interest on the capital value. According to the study, it is the rotation at which any money invested in lengthening the rotation still further, would yield no return. In the case of Scots pine, the highest income is achieved approximately with a rotation of 140 years, and the income per hectares would decrease if longer rotations were used, though the capital invested would increase.

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.

  • Hiley, ORCID ID:E-mail:
article id 7210, category Article
Erkki Laitakari. (1927). Männyn juuristo: morfologinen tutkimus. Acta Forestalia Fennica vol. 33 no. 1 article id 7210. https://doi.org/10.14214/aff.7210
English title: Morphological study of Scots pine root system.

The root systems of 192 Scots pine (Pinus sylvestris L.) sample trees were dug out and measured in Säyneinen, Rautavaara and Pielijsäjvi in the Central Finland and Orivesi, Teisko and Hämeenkyrö in the Southern Finland. The volume of root system of Scots pine was always smaller than the stem, varying from 15% to 94% of the stem volume. The ratio is smaller in dense stands. The type of soil of the site affects how the central root system (tap root and the inner vertical roots) develop. This reflect the adaptability of the root system to different growth conditions. The root system may, for instance, substitute the tap root with stronger inner roots.

PDF includes a summary in English.

  • Laitakari, ORCID ID:E-mail:
article id 7209, category Article
Aarne Boman. (1927). Tutkimuksia männyn paksuuskasvun monivuotisista vaihteluista Suomen eri osista kerätyn aineiston perusteella. Acta Forestalia Fennica vol. 32 no. 4 article id 7209. https://doi.org/10.14214/aff.7209
English title: Studies on annual variations of diameter growth of Scots pine in different parts of Finland.

Discs were collected from sample trees of Scots pine (Pinus sylvestris L.) in different types of peatlands and mineral soil sites in Kajaani, Rovaniemi, Kuusamo; Suojärvi, Pielisjärvi, Evo and Lokalahti in Finland. The growth ring series of the different areas reach as far as in the 1600th century in some sample plots. The diameter growth shows patterns that repeat in cycles of 7, 11, 21, 35 and 70 years. However, the cycles are not exactly equally long. The average lengths of the cycles are relatively similar both in peatlands and in mineral soil sites.

The PDF includes a summary in German.

  • Boman, ORCID ID:E-mail:
article id 5635, category Article
Tommi Ruha, Martti Varmola. (1997). Precommercial thinning in naturally regenerated Scots pine stands in northern Finland. Silva Fennica vol. 31 no. 4 article id 5635. https://doi.org/10.14214/sf.a8537

The effects of precommercial thinning on the quantity and external quality of young Scots pine (Pinus sylvestris L.) stands were examined over two 10-year periods in an experiment comprising five stands growing on sub-dry sites in Finnish Lapland, northern Finland. The thinning treatments applied resulted in stand densities of 625, 1111, 1600, 2500 and 4444 stems ha-1 and a no-treatment, unthinned plot with a randomised block lay-out of two or three replications in each stand. The dominant height of the stands varied between 4 and 8 m at the time of thinning.

The trees reacted only slightly to the increase in growing space during the first ten years following precommercial thinning. During the second 10-year period, increased growing space was reflected more clearly in diameter and volume increment. These reactions were more evident in stands thinned at an early stage. The increment of the thinnest 100–200 trees ha-1 in each treatment was poor. The results showed that when the main principle in precommercial thinning is to achieve even spacing, the remaining smallest trees fail to react positively to the increase in growing space. In other words, the target of precommercial thinning should be to concentrate the increment on the tallest trees, even though they are located in groups. The external quality of the trees in stands where precommercial thinning was carried out at a later stage was high, and the diameter of the thickest branch along the butt log remained under 20 mm. Branch diameter was greater in stands thinned at an early stage. The effect of precommercial thinning on branch diameter when comparing the extreme treatments averaged 5 mm. When the aim of stand management is to combine high quality and good yield in naturally regenerated Scots pine stands in northern Finland, precommercial thinning should not be carried out before the dominant height of 7–8 m. The intensity of precommercial thinning depends on the yield targets of the first commercial thinning. A spacing of 2,500 stems ha-1 satisfies the requirements of both high quality and adequate yield.

  • Ruha, ORCID ID:E-mail:
  • Varmola, ORCID ID:E-mail:
article id 5634, category Article
Leena Finér, Mika Nieminen. (1997). Dry mass and the amounts of nutrients in understorey vegetation before and after fertilization on a drained pine bog. Silva Fennica vol. 31 no. 4 article id 5634. https://doi.org/10.14214/sf.a8536

Dry mass and nutrient (N, P, K, Ca, Mg, B) contents of field layer vegetation and a combination of bottom layer vegetation and litter (referred to as bottom/litter layer in the text) were studied one year before and three years after fertilization (NPK and PK) on a drained low-shrub pine bog in eastern Finland. The results of an earlier study on the tree layer were combined with those of this study in order to estimate the changes caused by fertilization in the total plant biomass and litter. Before fertilization the average dry mass of the field and bottom/litter layers was 8,400 kg ha-1 and 7,650 kg ha-1, respectively. The above-ground parts accounted for 25% of the total field layer biomass. The dry mass of the field and bottom/litter layers together was < 20% of the dry mass accumulated in the total plant biomass and litter. The corresponding figures for N, P, K, Ca, Mg and B were 44%, 38%, 30%, 38%, 31% and 17%, respectively. Fertilization did not significantly affect the dry mass of either the field layer vegetation or the bottom/litter layer. 33% of the applied P was accumulated in the total plant biomass and litter on the PK-fertilized plots, and 25% on the NPK-fertilized plots. For the other elements, the proportions on the PK-fertilized plots were K 31%, Ca 6%, Mg 11% and B 13%. On the NPK-fertilized plots, the corresponding figures were N 62%, K 32%, Ca 6%, Mg 9% and B 13%. Except for B and K, the accumulation of fertilizer nutrients in the understorey vegetation and litter was of the same magnitude or greater than the uptake by the tree layer.

  • Finér, ORCID ID:E-mail:
  • Nieminen, ORCID ID:E-mail:
article id 5632, category Article
Annikki Mäkelä, Veli-Pekka Ikonen, Petteri Vanninen. (1997). An application of process-based modelling to the development of branchiness in Scots pine. Silva Fennica vol. 31 no. 3 article id 5632. https://doi.org/10.14214/sf.a8534

A process-oriented tree and stand growth model is extended to be applicable to the analysis of timber quality, and how it is influenced by silvicultural treatments. The tree-level model is based on the carbon balance and it incorporates the dynamics of five biomass variables as well as tree height, crown base, and breast height diameter. Allocation of carbon is based on the conservation of structural relationships, in particular, the pipe model. The pipe-model relationships are extended to the whorl level, but in order to avoid a 3-dimensional model of entire crown structure, the branch module is largely stochastic and aggregated. In model construction, a top-down hierarchy is used where at each step down, the upper level sets constraints for the lower level. Some advantages of this approach are model consistency and efficiency of calculations, but probably at the cost of reduced flexibility. The detailed structure related with the branching module is preliminary and will be improved when more data becomes available. Model parameters are identified for Scots pine (Pinus sylvestris L.) in Southern Finland, and example simulations are carried out to compare the development of quality characteristics in different stocking densities.

  • Mäkelä, ORCID ID:E-mail:
  • Ikonen, ORCID ID:E-mail:
  • Vanninen, ORCID ID:E-mail:
article id 5629, category Article
Risto Sievänen, Eero Nikinmaa, Jari Perttunen. (1997). Evaluation of importance of sapwood senescence on tree growth using the model Lignum. Silva Fennica vol. 31 no. 3 article id 5629. https://doi.org/10.14214/sf.a8531

The effects of two alternative formulations of sapwood senescence on the behaviour of model LIGNUM (with parameter values adjusted for Scots pine (Pinus sylvestris L.) growing southern Finland) were studied. The two alternatives were autonomous sapwood senescence assuming a maximum age for the tree ring, and sapwood senescence that is controlled by the mortality of foliage. For the latter alternative two hypothetical further mechanisms were stipulated. All the formulations were implemented in LIGNUM. Simulations were made with all model variants for fertile and poor soil conditions using high, normal and low rates of foliage mortality. The simulation results were compared against of a data set consisting of 11 open grown Scots pine trees from southern Finland. Observations of heartwood proportion were used in this study. They show that heartwood starts to increase in trees from age of approximately 20 years onwards. The simulation results showed no differences between fertile and poor soil conditions as regards heartwood formation. Of the variants of foliage-controlled sapwood senescence the one where death of sapwood in a tree segment induces sapwood senescence in the tree parts below only slightly was the best. This and the autonomous sapwood senescence corresponded equally well to the observations. In order to make more refined conclusions additional data and simulations are necessary.

  • Sievänen, ORCID ID:E-mail:
  • Nikinmaa, ORCID ID:E-mail:
  • Perttunen, ORCID ID:E-mail:
article id 5616, category Article
Hannu Hökkä, Virpi Alenius, Timo Penttilä. (1997). Individual-tree basal area growth models for Scots pine, pubescent birch and Norway spruce on drained peatlands in Finland. Silva Fennica vol. 31 no. 2 article id 5616. https://doi.org/10.14214/sf.a8517

Models for individual-tree basal area growth were constructed for Scots pine (Pinus sylvestris L.), pubescent birch (Betula pubescens Ehrh.) and Norway spruce (Picea abies (L.) Karst.) growing in drained peatland stands. The data consisted of two separate sets of permanent sample plots forming a large sample of drained peatland stands in Finland. The dependent variable in all models was the 5-year basal area growth of a tree. The independent tree-level variables were tree dbh, tree basal area, and the sum of the basal area of trees larger than the target tree. Independent stand-level variables were stand basal area, the diameter of the tree of median basal area, and temperature sum. Categorical variables describing the site quality, as well as the condition and age of drainage, were used. Differences in tree growth were used as criteria in reclassifying the a priori site types into new yield classes by tree species. All models were constructed as mixed linear models with a random stand effect. The models were tested against the modelling data and against independent data sets.

  • Hökkä, ORCID ID:E-mail:
  • Alenius, ORCID ID:E-mail:
  • Penttilä, ORCID ID:E-mail:
article id 5611, category Article
Arja Lilja, Timo Kurkela, Sakari Lilja, Risto Rikala.. (1997). Nursery practices and management of fungal diseases in forest nurseries in Finland. A review. Silva Fennica vol. 31 no. 1 article id 5611. https://doi.org/10.14214/sf.a8512

The purpose of this article was to collate the literature on fungal diseases that occur on seedlings in forest nurseries. It describes the symptoms of the diseases, the infection pattern of each fungus and the possibilities of controlling the diseases. As background a short introduction is given on forests and nursery practices in Finland.

  • Lilja, ORCID ID:E-mail:
  • Kurkela, ORCID ID:E-mail:
  • Lilja, ORCID ID:E-mail:
  • Rikala., ORCID ID:E-mail:
article id 5609, category Article
Matti Maltamo. (1997). Comparing basal area diameter distributions estimated by tree species and for the entire growing stock in a mixed stand. Silva Fennica vol. 31 no. 1 article id 5609. https://doi.org/10.14214/sf.a8510

The purpose of this study was to compare the Weibull distributions estimated for the entire growing stock of a stand and separately for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) in describing the basal area diameter distributions in mixed stands. The material for this study was obtained by measuring 553 stands located in eastern Finland. The parameters of the Weibull distribution were estimated using the method of maximum likelihood. The models for these parameters were derived using regression analysis. Also, some parameter models from previous studies were compared with the measured distribution. The obtained distributions were compared using the diameter sums of the entire growing stock, diameter sums by tree species and of the sawtimber part of the growing stock. The results showed that far more accurate results were obtained when the distributions were formed using parameter models separately for the different tree species than when using parameter models for the entire growing stock. This was already true when considering the entire growing stock of the stand and especially when the results were examined by tree species. When the models for the entire growing stock were applied by tree species in relation to basal areas, the results obtained were overestimates for Norway spruce and underestimates for Scots pine. The models from earlier studies, where parameter models were estimated separately for tree species from the National Forest Inventory data, showed good fits also in regard to the data of this study.

  • Maltamo, ORCID ID:E-mail:
article id 5608, category Article
Harri Mäkinen. (1997). Possibilities of competition indices to describe competitive differences between Scots pine families. Silva Fennica vol. 31 no. 1 article id 5608. https://doi.org/10.14214/sf.a8509

Possibilities of distance-independent and -dependent competition indices to describe the competition stress of an individual tree was studied in Southern Finland. Five half-sib open-pollinated families and one check lot of Scots pine (Pinus sylvestris L.) was used as study material in order to analyse competitive interactions of crown form and stand density variation. Almost all competition indices correlated strongly with radial increment. Thus distance-independent indices were adequate to describe competition in young row plantations, where distance effects between trees were implicitly eliminated. Correlations between indices and height increment were not significant. Along with the increase in competition, the width and length of the crown and the diameter increment of the stem of some narrow-crowned families decreased slowly compared to wide-crowned families.

  • Mäkinen, ORCID ID:E-mail:
article id 5605, category Article
Matti Haapanen, Marja-Leena Annala, Pirkko Velling. (1997). Progeny trial estimates of genetic parameters for growth and quality traits in Scots pine. Silva Fennica vol. 31 no. 1 article id 5605. https://doi.org/10.14214/sf.a8506

Estimates of individual heritability and genetic correlation are presented for a set of 10 growth and quality traits based on data from 16 Scots pine (Pinus sylvestris L.) progeny trials in Finland. Seven of the traits (tree height, stem diameter, crown width, Pilodyn value, branch diameter, branch angle and branch number) were objectively measured, whereas three traits (stem straightness, branching score and overall score) were assessed visually. The genetic correlations were mostly moderate or low, and favourable from the tree breeder's point of view. All variables related to tree size correlated relatively strongly and positively. Tree height exhibited a more favourable genetic relationship with the crown form traits than diameter, the latter showing positive correlation with branch diameter. Except for the slight negative correlation between branch angle and branch diameter, the branching traits were not notably correlated. The pilodyn value was positively correlated with stem diameter, reflecting negative correlation between diameter growth and wood density. The highest genetic correlations occurred among the two visually evaluated quality scores and branch diameter. All of the heritabilities were less than 0.4. Overall score, Pilodyn, branch angle, branching score and tree height showed the highest heritability.

  • Haapanen, ORCID ID:E-mail:
  • Annala, ORCID ID:E-mail:
  • Velling, ORCID ID:E-mail:
article id 5565, category Article
Tytti Sarjala, Seppo Kaunisto. (1996). Effect of different potassium sources on the seasonal variation of potassium and free polyamines in Scots pine needles. Silva Fennica vol. 30 no. 4 article id 5565. https://doi.org/10.14214/sf.a8500

Seasonal fluctuations in free polyamines, spermidine, spermine, putrescine and potassium concentrations were studied for two years (1992–1993) in three needle years of Scots pine (Pinus sylvestris L.) grown on a drained mire in western Finland. Seven different fertilizer treatments involving five different sources of potassium were used.

Putrescine concentrations were high in winter and in May but low in summer. High peaks in putrescine in March and May could be found in unrefertilized or rock phosphate treatments. Spermidine and spermine concentrations were high in March and May. In December spermine concentrations were low. Biotite increased the needle potassium concentrations less than the other potassium fertilizers but the putrescine concentrations or the putrescine/spermidine ratio to about the same level. This suggests that biotite, although very slowly soluble, can reasonably satisfy potassium nutrition of young pine trees.

The potassium concentrations of needles in all the fertilization treatments were higher in winter than in summer. The response of putrescine to the potassium concentration was strongly negative in all the needle years and sampling times. In March, May and December the response of putrescine to potassium was fairly similar in both years but not in June and August. The results suggest that the potassium concentrations during the growing season cannot be used for estimating the potassium nutrition of trees, because the variation between the years may be substantial, whereas the needle putrescine concentration or putrescine/spermidine ratio indicates the suboptimum potassium status of Scots pine fairly well. Needle putrescine concentrations over 500 nmol g-1FW quite regularly coincided with a unsatisfactory potassium nutrition and concentrations over 1,000 nmol g-1FW were a reliable indication of potassium deficiency. Putrescine/spermidine ratios below 5 indicated a satisfactory potassium nutrition in all needle years throughout the year.

  • Sarjala, ORCID ID:E-mail:
  • Kaunisto, ORCID ID:E-mail:
article id 5599, category Article
Vadim V. Gorshkov, Irene J. Bakkal. (1996). Species richness and structure variations of Scots pine forest communities during the period from 5 to 210 years after fire. Silva Fennica vol. 30 no. 2–3 article id 5599. https://doi.org/10.14214/sf.a9244

Postfire recovery of species diversity (including a number of species, entropy of species relative coverage (Shannon index of species diversity) was studied in lichen and green moss site types of Scots pine (Pinus sylvestris L.) forests in the central part of the Kola Peninsula. The results obtained indicate the difference in the dynamics of characteristics of biodiversity of forest components during postfire recovery. The stabilization of separate components of forest community varies in time from 5–15 to 120–140 years after the fire. Characteristics of the dwarf shrub and herb stratum recovered and stabilized 5–15 years after fire, while the complete stabilization of characteristics of moss-lichen cover is observed in community with fire ages of 90–140 years. Species richness of tree stratum recovered 120–140 years after fire. Time of complete stabilization of species richness of the community was estimated 120–140 years after fire. The size of the area over which characteristics of the biodiversity were estimated effected the mean values and, in most cases, the character of variation of studied characteristics. Over an area of 1 x 1 m dynamics of characteristics of species diversity coincide in forests of the studied types. Regardless of forest type within the area of 100 m2 species richness recovered 30 years after the fire (i.e. 3–5 times earlier than the establishment of the complete stabilization of the forest structure). That means that floristic composition of the forest remained unchanged from 30 to 210 years after the fire.

  • Gorshkov, ORCID ID:E-mail:
  • Bakkal, ORCID ID:E-mail:
article id 5591, category Article
Egbert Beuker, Seppo Kellomäki, Marja Kolström. (1996). Changes in wood production of Picea abies and Pinus sylvestris under a warmer climate: comparison of field measurements and results of a mathematical model. Silva Fennica vol. 30 no. 2–3 article id 5591. https://doi.org/10.14214/sf.a9236

To project the changes in wood production of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) in Finland as a result of climate change, two separate studies were made. The first study, at the Faculty of Forestry, University of Joensuu, based its projections on mathematical models; the second one, at the Finnish Forest Research Institute, based projections on measurements of wood production in two series of aged provenance experiments. The results of the two studies were similar for both species: after a 4°C increase of the annual mean temperature a drastic increase in wood production in northern Finland, but little effect, or even some decrease in the southern part of the country. However, the assumptions used in the two studies differed. One important difference was that in the models the temperature is assumed to be increasing gradually over the years, whereas in the provenance experiments, climate changed immediately when the seedlings were transferred to the planting sites. Another problem with the provenance experiments is that when material is moved in a north-south direction in Finland, not only temperature but also photoperiod changes markedly. To compare these two studies, site factors (e.g. soil type, temperature, precipitation) and silvicultural factors (e.g. plant spacing, survival, time of thinning, thinning intensity) from the provenance experiments were included a variable in the mathematical models.

  • Beuker, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Kolström, ORCID ID:E-mail:
article id 5590, category Article
Heikki Hänninen, Seppo Kellomäki, Ilkka Leinonen, Tapani Repo. (1996). Overwintering and productivity of Scots pine in a changing climate. Silva Fennica vol. 30 no. 2–3 article id 5590. https://doi.org/10.14214/sf.a9235

The productivity of Scots pine (Pinus sylvestris L.) under changing climatic conditions in the southern part of Finland was studied by scenario analysis with a gap-type forest ecosystem model. Standard simulations with the model predicted an increased rate of growth and hence increased productivity as a result of climatic warming. The gap-type model was refined by introducing an overwintering sub-model describing the annual growth cycle, frost hardiness, and frost damage of the trees. Simulations with the refined gap-type model produced results conflicting with those of the standard simulation, i.e., drastically decreased productivity caused by mortality and growth-reducing damage due to premature dehardening in the changing climate. The overwintering sub-model was tested with frost hardiness data from Scots pine saplings growing at their natural site 1) under natural conditions and 2) under elevated temperature condition, both in open-top chambers. The model predicted the frost hardiness dynamics quite accurately for the natural conditions while underestimating the frost hardiness of the saplings for the elevated temperature conditions. These findings show that 1) the overwintering sub-model requires further development, and 2) the possible reduction of productivity caused by frost damage in a changing climate is less drastic than predicted in the scenario analysis. The results as a whole demonstrated the need to consider the overwintering of trees in scenario analysis carried out with ecosystem model for boreal conditions. More generally, the results revealed a problem that exists in scenario analysis with ecological models: the accuracy of a model in predicting the ecosystem functioning under present climatic condition does not guarantee the realism of the model, nor for this reason the accuracy for predicting the ecosystem functioning under changing climatic conditions. This finding calls for the continuous rigorous experimental testing of ecological models used for assessing the ecological implications of climatic change.

  • Hänninen, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Leinonen, ORCID ID:E-mail:
  • Repo, ORCID ID:E-mail:
article id 5588, category Article
Vadim V. Gorshkov, Irene J. Bakkal, Natalie I. Stavrova. (1996). Postfire recovery of forest litter in Scots pine forests in two different regions of boreal zone. Silva Fennica vol. 30 no. 2–3 article id 5588. https://doi.org/10.14214/sf.a9233

Investigations carried out in the Kola peninsula (northern taiga) and in the South-western part of Western Siberia (southern taiga and forest-steppe) revealed identical course of the postfire restoration process of forest litter thickness in Scots pine (Pinus sylvestris L.) forests. Despite the differences in mean annual temperature (2°C) and other climatic characteristics the recovery time for thickness of forest litter in both regions amounts to 90–100 years after fire in pine forests of lichen site type and 120–140 years – in green moss type; the thickness of forest litter therewith corresponds 3–4 cm and 7–8 cm respectively. That mean that within the natural borders of pine forests, communities of a specific type possess uniform characteristics of restoration. On the basis of empirical data, it appears that the predicted increase of mean annual temperature of earth surface by (2°C) will not bring changes into the character of postfire recovery of forest litter thickness. It was shown that during the period of the recovery, which spans about 90 years after fire in pine forests of lichen and green moss-lichen site types and 140 years in ones of green moss site types, the rate of increasing of carbon store in the forest litter averaged 0.6 t ha-1 year-1, 0.1 t ha-1 year-1 and 0.2 t ha-1 year-1, respectively.

  • Gorshkov, ORCID ID:E-mail:
  • Bakkal, ORCID ID:E-mail:
  • Stavrova, ORCID ID:E-mail:
article id 5585, category Article
Päivi Lyytikäinen, Jarmo K. Holopainen, Pirjo Kainulainen, Anne Nerg, Seppo Neuvonen, Tarmo Virtanen. (1996). Performance of pine sawflies under elevated tropospheric ozone. Silva Fennica vol. 30 no. 2–3 article id 5585. https://doi.org/10.14214/sf.a9230

Concentration of the phytotoxic air pollutant, ozone (O3) is continually increasing in the lower layer of the troposphere. The purpose of this study was to compare performance of pine sawflies on Scots pine (Pinus sylvestris L.) seedlings in ambient and future levels of ozone. Scots pine seedlings were grown in field fumigation system where the ozone doses in fumigated plots were 1.5–1.6 times the ambient level. Larvae of the European pine sawfly (Neodiprion sertifer Geoffroy and Gilpinia pallida Klug) were reared on the foliage of Scots pine. The levels of resin acids and monoterpenes in foliage were analysed. There were no significant effects of ozone fumigation on sawfly performance or levels of defence compounds in pine foliage. The results suggest that the elevated ozone concentrations do not strongly affect the needle quality of young Scots pine and the importance of these two diprionid sawfly species forest pests.

  • Lyytikäinen, ORCID ID:E-mail:
  • Holopainen, ORCID ID:E-mail:
  • Kainulainen, ORCID ID:E-mail:
  • Nerg, ORCID ID:E-mail:
  • Neuvonen, ORCID ID:E-mail:
  • Virtanen, ORCID ID:E-mail:
article id 5584, category Article
Tarmo Virtanen, Seppo Neuvonen, Pekka Niemelä, Ari Nikula, Martti Varama. (1996). Climate change and the risks of Neodiprion sertifer outbreaks on Scots pine. Silva Fennica vol. 30 no. 2–3 article id 5584. https://doi.org/10.14214/sf.a9229

The European Pine Sawfly (Neodiprion sertifer Geoffroy) is one of the most serious defoliators of Scots pine (Pinus sylvestris L.) in northern Europe. We studied the pattern in the regional occurrence of the outbreaks of N. sertifer in Finland in years 1961-90, and made predictions about the outbreak pattern to the year 2050 after predicted winter warming. We tested whether minimum winter temperatures and forest type and soil properties could explain the observed outbreak pattern. We analysed outbreak patterns at two different spatial levels: forest board- and municipal-level.

The proportion of coniferous forests on damage-susceptible soils (dry and infertile sites) explained a significant part of the variation in outbreak frequency at small spatial scale (municipalities) but not at large spatial scale (forest boards). At the forest board level, the incidence of minimum temperatures below -36 °C (= the critical value for egg mortality) explains 33% of the variation in the outbreak pattern, and at the municipal level the incidence of cold winters was also the most significant explaining variable in northern Finland. Egg mortality due to cold winters seems to be the most parsimonious factor explaining why there have been so few N. sertifer outbreaks in northern and north-eastern Finland. We predict that climate change (increased winter temperatures) may increase the frequency of outbreaks in eastern and northern Finland in the future.

  • Virtanen, ORCID ID:E-mail:
  • Neuvonen, ORCID ID:E-mail:
  • Niemelä, ORCID ID:E-mail:
  • Nikula, ORCID ID:E-mail:
  • Varama, ORCID ID:E-mail:
article id 5583, category Article
Ilkka Leinonen, Heikki Hänninen, Tapani Repo. (1996). Testing of frost hardiness models for Pinus sylvestris in natural conditions and in elevated temperature. Silva Fennica vol. 30 no. 2–3 article id 5583. https://doi.org/10.14214/sf.a9228

Two dynamic models predicting the development of frost hardiness of Finnish Scots pine (Pinus sylvestris L.) were tested with frost hardiness data obtained from trees growing in the natural conditions of Finland and from an experiment simulating the predicted climatic warming. The input variables were temperature in the first model, and temperature and night length in the second. The model parameters were fixed on the basis of previous independent studies. The results suggested that the model which included temperature and photoperiod as input variables was more accurate than the model using temperature as the only input variable to predict the development of frost hardiness in different environmental conditions. Further requirements for developing the frost hardiness models are discussed.

  • Leinonen, ORCID ID:E-mail:
  • Hänninen, ORCID ID:E-mail:
  • Repo, ORCID ID:E-mail:
article id 5580, category Article
Virpi Palomäki, Toini Holopainen, Seppo Kellomäki, Kaisa Laitinen. (1996). First-year results on the effects of elevated atmospheric CO2 and O3 concentrations on needle ultrastructure and gas exchange responses of Scots pine saplings. Silva Fennica vol. 30 no. 2–3 article id 5580. https://doi.org/10.14214/sf.a9225

The effects of realistically elevated O3 and CO2 concentrations on the needle ultrastructure and photosynthesis of ca. 20-year-old Scots pine (Pinus sylvestris L.) saplings were studied during one growth period in open-top field chambers situated on a natural pine heath at Mekrijärvi, in eastern Finland. The experiment included six different treatments: chamberless control, filtered air, ambient air and elevated O3, CO2 and O3 + CO2. Significant increases in the size of chloroplast and starch grains were recorded in the current-year needles of the saplings exposed to elevated CO2 These responses were especially clear in the saplings exposed to elevated O3 + CO2 concentrations. These treatments also delayed the winter hardening process in cells. In the shoots treated with O3, CO2 and combined O3 + CO2 the Pmax was decreased on average by 50% (ambient CO2) and 40% (700 ppm CO2). Photosynthetic efficiency was decreased by 60% in all the treated shoots measured under ambient condition and by 30% in the CO2 and O3 + CO2 treated shoots under 700 ppm. The effect of all the treatments on photosynthesis was depressive which was probably related to evident accumulation of starch in the chloroplasts of the pines treated with CO2 and combined O3 + CO2. But in O3 treated pines, which did not accumulate starch in comparison to pines subjected to ambient air conditions, some injuries may be already present in the photosynthetic machinery.

  • Palomäki, ORCID ID:E-mail:
  • Holopainen, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Laitinen, ORCID ID:E-mail:
article id 5578, category Article
Mika Aurela, Tuomas Laurila, Juha-Pekka Tuovinen. (1996). Measurements of O3, CO2 and H2O fluxes over a Scots pine stand in eastern Finland by the micrometeorological eddy covariance method. Silva Fennica vol. 30 no. 2–3 article id 5578. https://doi.org/10.14214/sf.a9223

The eddy covariance technique is a novel micrometeorological method that enables the determination of the atmosphere-biosphere exchange rate of gases such as ozone and carbon dioxide on an ecosystem scale. This paper describes the technique and presents results from the first direct measurements of turbulent fluxes of O3, CO2 and H2O above a forest in Finland. The measurements were performed during 15 July-5 August 1994 above a Scots pine (Pinus sylvestris L.) stand near the Mekrijärvi research station in Eastern Finland.

The expected diurnal cycles were observed in the atmospheric fluxes of O3, CO2 and H2O. The data analysis includes interpretation of the O3 flux in terms of the dry deposition velocity and evaluation the dependency of the net CO2 flux on radiation. The eddy covariance method and the established measurement system has proved suitable for providing high-resolution data for studying ozone deposition to a forest as well as the net carbon balance and related physiological processes of an ecosystem.

  • Aurela, ORCID ID:E-mail:
  • Laurila, ORCID ID:E-mail:
  • Tuovinen, ORCID ID:E-mail:
article id 5574, category Article
Jouni Vettenranta. (1996). Effect of species composition on economic return in a mixed stand of Norway spruce and Scots pine. Silva Fennica vol. 30 no. 1 article id 5574. https://doi.org/10.14214/sf.a9219

The effect of species mixture was studied in a mixed stand of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) by simulating around 100 different treatment schedules during the rotation in a naturally regenerated even-aged stand located on a site of medium fertility in North Karelia, Finland. Both thinning from below and thinning from above were applied. Optimum rotations were determined by maximising the net present value calculated to infinity and different treatment schedules were compared with the net present value over one rotation as per rotation applied. In the optimum treatment programme, the proportion of pines was decreased by half of the basal area in the first thinning stage and by the end of the rotation to about one third. In thinning from above, the proportion of pines can be maintained at a slightly higher level. It is economically profitable to maintain the growing stock capital at approximately the level recommended by Forest Centre Tapio, a semi-governmental forestry authority. With non-optimum species composition, the loss in net present value over one rotation can be about 10 % in thinning from below and about 20 % in thinning from above.

  • Vettenranta, ORCID ID:E-mail:
article id 5573, category Article
Ilkka Vanha-Majamaa, Raili Suominen, Tiina Tonteri, Eeva-Stiina Tuittila. (1996). Seedling establishment after prescribed burning of a clear-cut and a partially cut mesic boreal forest in southern Finland. Silva Fennica vol. 30 no. 1 article id 5573. https://doi.org/10.14214/sf.a9218

The prescribed burning of a 7.3 ha clear-cut and a 1.7 ha partially cut forest (volume 150 m3/ha) was carried out in Evo (61 °12'N, 25°07'E) on 1 June 1992. The forest was a mesic Myrtillus site type forest dominated by Norway spruce (Picea abies (L.) H. Karst.). Practically all the trees and the above-ground parts of the understorey vegetation died in the fire, while the mor layer was thinned by an average of 1.5 cm.

A study was made on the change of germinated seedling population in time and their dependence on environmental factors. Seedlings of Norway spruce, Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth), pubescent birch (B. pubescens Ehrh.) and rowan (Sorbus aucuparia L.) were inventoried in 1993 and in 1994 on permanent plots, four times per growing season. Autoregression models were used to compare regeneration of tree species in the burned forest with regeneration in the burnt clear-cut area, and to study the effect of distance from nearest seed source to regeneration.

The average number of seedlings germinating in 1993 was higher than in 1994, probably because of differences between these consecutive years in regard to the amount of seed rain and weather conditions. The number of Norway spruce and rowan seedling was higher inside the forest area than in the clear-cut area. The distance to the bordering forest and to the closest seed tree did not explain the result. It is suggested that the more stable microclimatic conditions under the shade of dead tree promote germination and seedling establishment in the forest area. As rowan is a bird-dispersed species, it is likely that dead trees help the dispersal of rowan seed by providing birds place to sit and defecate. The shade provided by dead trees may influence the further succession of the tree stand and vegetation composition and diversity.

  • Vanha-Majamaa, ORCID ID:E-mail:
  • Suominen, ORCID ID:E-mail:
  • Tonteri, ORCID ID:E-mail:
  • Tuittila, ORCID ID:E-mail:
article id 5571, category Article
Katarina Lindgren, Dag Lindgren. (1996). Germinability of Norway spruce and Scots pine pollen exposed to open air. Silva Fennica vol. 30 no. 1 article id 5571. https://doi.org/10.14214/sf.a9216

Germination of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) pollen decreased during exposure to open air conditions. Usually more than half of the pollen remained germinative after a few days outdoors, but following more than four days outdoors the germination became very low. This study supports the opinion that pollen in the atmosphere remains viable long enough to allow for long-distance gene flow by pollen migration, as an important factor in genetic management of conifers and in evolution, maintaining diversity and potential for adaptation.

  • Lindgren, ORCID ID:E-mail:
  • Lindgren, ORCID ID:E-mail:
article id 7194, category Article
T. Heikkilä. (1925). Kasvututkimuksia Perä-Pohjolasta. Acta Forestalia Fennica vol. 29 no. 4 article id 7194. https://doi.org/10.14214/aff.7194
English title: Growth studies in the northernmost Finland.

There is little knowledge about the value increment of the stands that are about to become mature for felling. Sample plots were measured in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands in the most common forest site types in Rovaniemi, in northernmost Finland. Sample trees were chosen from dominant and codominant trees of the stand.

The value increments for the stands were generally very low. The average rotation of the studied stands would be 160 years. In the better forest site type, the increments of basal-area, volume and form height decrease slowly as the diameter of the tree increases. The value increment can give valuable information for intermediate fellings. They should be targeted mainly to large codominant trees and partly also in dominant trees that do not yet give logs, because their value increment is low.

The PDF includes a summary in German.

  • Heikkilä, ORCID ID:E-mail:
article id 5563, category Article
Margaret Penner, Hannu Hökkä, Timo Penttilä. (1995). A method for using random parameters in analyzing permanent sample plots. Silva Fennica vol. 29 no. 4 article id 5563. https://doi.org/10.14214/sf.a9214

The use of random parameter models in forestry has been proposed as one method of incorporating different levels of information into prediction equations. By explicitly considering the variance-covariance structure of observations and considering some model parameters as random rather than fixed, one can incorporate more complex error structures in analysing data.

Competition indices and variance component techniques were applied to 92 Scots pine (Pinus sylvestris L.) -dominated permanent sample plots on drained peatlands in Northern Finland. By quantifying stand, plot, and tree level variation, it was possible to identify the level (stand, plot or tree) at which the explanatory variables contributed to the model. The replication of plots within stands revealed little variation among plots within a single stand but significant variation occurred at stand and tree levels. Positive and negative effects of inter-tree competition are identified by examining simple correlation statistics and the random parameter model.

  • Penner, ORCID ID:E-mail:
  • Hökkä, ORCID ID:E-mail:
  • Penttilä, ORCID ID:E-mail:
article id 5561, category Article
Jari Liski. (1995). Variation in soil organic carbon and thickness of soil horizons within a boreal forest stand – effect of trees and implications for sampling. Silva Fennica vol. 29 no. 4 article id 5561. https://doi.org/10.14214/sf.a9212

Spatial variation in the density of soil organic carbon (kg/m2) and the thickness of soil horizons (F/H, E) were investigated in a 6 m x 8 m area in Scots pine (Pinus sylvestris L.) stand in Southern Finland for designing an effective sampling for the C density and studying the effect of trees on the variation. The horizon thickness of the podzolized soil were measured on a total of 126 soil cores (50 cm deep) and the C density of the organic F/H and 0–10 cm, 10–20 cm and 20–40 cm mineral soil layers was analysed.

The C density varied 3–5 fold within the layers and the coefficients of variation ranged from 22 % to 40%. Considering the gain in confidence per sample, 8–10 samples were suggested for estimating the mean C density in the F/H and 0–40 cm layers, although about 30 samples are needed for 10% confidence in the mean. The C densities and horizon thicknesses were spatially dependent within the distances of 1–8 m, the spatial dependence accounting for 43–86% of the total variance. The F/H layer was thicker and contained more C within 1–3 m radius from trees. In the 10–20 cm and 20–40 cm layers (B horizon) the C density also increased towards the trees, but more pronouncedly in the immediate vicinity of the stems. Because the spatial patterning of the E horizon thickness was similar, the increase was attributed to stemflow and precipitation of organic compounds in the podzol B horizon.

  • Liski, ORCID ID:E-mail:
article id 5559, category Article
Jari Hynynen. (1995). Predicting the growth response to thinning for Scots pine stands using individual-tree growth models. Silva Fennica vol. 29 no. 3 article id 5559. https://doi.org/10.14214/sf.a9210

Individual tree-growth models for diameter and height, and a model for the cylindrical stem form factor are presented. The aims of the study were to examine modelling methods in predicting growth response to thinning, and to develop individual-tree, distance-independent growth models for predicting the development of thinned and unthinned stands of Scots pine (Pinus sylvestris L.). The models were constructed to be applicable in simulation systems used in practical forest management planning. The models were based on data obtained from eleven permanent thinning experiments located in even-aged Scots pine stands in Southern and Central Finland.

Two alternative models were developed to predict tree diameter growth in thinned and unthinned stands. In the first model, the effect of stand density was described using stand basal area. In the alternative model, an explicit variable was incorporated referring to the relative growth response due to thinning. The magnitude of the growth response was expressed as a function of thinning intensity. The Weibull function was employed to describe the temporal distribution of the thinning response. Both models resulted in unbiased predictions in unthinned and in moderately thinned stands. An explicit thinning variable was needed for unbiased growth prediction in heavily thinned stands, and in order to correctly predict the dynamics of the growth response.

In the height growth model, no explicit thinnning variable referring thinning was necessary for growth prediction in thinned stands. The stem form factor was predicted using the model that included tree diameter and tree height as regressor variables. According to the results obtained, the information on the changes in the diameter/height ratio following the thinning is sufficient to predict the change in stem form.

  • Hynynen, ORCID ID:E-mail:
article id 5557, category Article
Klaus Silfverberg. (1995). Forest regeneration on nutrient-poor peatlands: Effects of fertilization, mounding and sowing. Silva Fennica vol. 29 no. 3 article id 5557. https://doi.org/10.14214/sf.a9208

The effects of wood ash and PK fertilization on natural regeneration and sowing of Scots pine (Pinus sylvestris L.) were studied in field experiments on nitrogen-poor (Ntot 0.87–1.26%) peat substrates. The study material was derived from three drained, nutrient-poor pine mires (64°52’ N, 25°08’ E) at Muhos, near Oulu, Finland. The experimental fields were laid out in 1985 as a split-split-plot design including the following treatments; mounding, natural regeneration and sowing and fertilization; PK (400 kg ha-1) and wood ash (5,000 kg ha-1). The seedlings were inventoried in circles in July–August 1991.

Changes in the vegetation were small and there were no statistical differences due to the fertilization treatments in the ground vegetation. PK or ash fertilization did not cause vegetation changes harmful to Scots pine regeneration on nitrogen-poor peatlands. Both sowing and fertilization significantly increased the number of pine seedlings, but not their height. Wood ash increased seedling number more than PK fertilizer. The number of seedlings varied from 7,963 (control) to 42,781 ha-1 (mounding + sowing + ash). The seedling number was adequate for successful regeneration even on non-mounded, non-fertilized naturally regenerated plots.

The number of birch seedlings varied more than that of pine (370–25,927 ha-1). Mounding especially increased the number of birches. The difference between PK fertiliser and ash was less pronounced than that for pine. In addition, to the field studies the effects of ash and PK fertilizer on the germination of Scots pine seeds was studied in a greenhouse experiment. Soaking in ash solutions strongly reduced seed germination, while the PK solution was less harmful.

  • Silfverberg, ORCID ID:E-mail:
article id 5556, category Article
Timo J. Hokkanen, Erkki Järvinen, Timo Kuuluvainen. (1995). Properties of top soil and the relationship between soil and trees in a boreal Scots pine stand. Silva Fennica vol. 29 no. 3 article id 5556. https://doi.org/10.14214/sf.a9207

One-hectare plot in a Scots pine (Pinus sylvestris L.) forest was systemically sampled for surface soil characteristics: humus layer thickness, soil carbon and nitrogen content, pH, electrical conductivity and respiration were determined from 106 samples. The effects of large trees on the plot were mapped and their joint influences at the locations of soil sampling were described as the influence potential, derived from the ecological field theory, and were calculated based on the locations and dimensions of trees.

The range of variation of soil characteristics was from three to sevenfold; no spatial autocorrelation was detected. The calculated influence potential of trees, as determined by their size and spatial distribution, was related to the spatial variation of top soil properties. Top soil properties were also related to thickness of the humus layer but they were poorly correlated with underlying mineral soil characteristics. Humus layer thickness, with the calculated influence potential of trees, may provide a means to predict top soil characteristics in specific microenvironments in the forest floor.

  • Hokkanen, ORCID ID:E-mail:
  • Järvinen, ORCID ID:E-mail:
  • Kuuluvainen, ORCID ID:E-mail:
article id 5552, category Article
Liisa Saarenmaa, Timo Leppälä. (1995). Fill-in seedlings in constituting the stocking of Scots pine stands in northern Finland. Silva Fennica vol. 29 no. 2 article id 5552. https://doi.org/10.14214/sf.a9203

Fill planting is a common procedure following reforestation in Finland. In 1990, 13% of the total of seedlings planted was used for fill planting. The objective of this study is (i) to survey the survival of fill-in seedlings and (ii) to estimate the spatial pattern of stands to evaluate the importance of fill-in seedlings in constituting the stocking of Scots pine (Pinus sylvestris L.) stands in Central and Northern Finland.

A survey of 63 artificially regenerated Scots pine stands was conducted in 1990. Stand densities varied from 950 to 3,925 seedlings/ha. The mean densities of originally planted, fill planted and naturally regenerated seedlings were 863, 639 and 791/ha, respectively. The survival of originally planted seedlings was 36% and that of fill-in seedlings 48%. Death rate of fill-in seedlings of Scots pine increased with longer times between original and fill planting. The survival rate of Norway spruce (Picea abies) seedlings was correlated with temperature sum. Height of the fill-in seedlings was less than that of the originally planted ones. Most stands had an even spatial distribution with the exception of sparsely populated stands, which were somewhat clustered. This indicates that dying of seedlings is not randomly spread. Because of poor survival, fill planting seems to be a risky business in most cases.

  • Saarenmaa, ORCID ID:E-mail:
  • Leppälä, ORCID ID:E-mail:
article id 5545, category Article
Jouni Siipilehto, Olavi Lyly. (1995). Weed control trials with fibre mulch, glyphosate and terbuthylazine in Scots pine plantations. Silva Fennica vol. 29 no. 1 article id 5545. https://doi.org/10.14214/sf.a9196

The following treatments were compared in three Scots pine (Pinus sylvestris L.) reforestation areas on a scarified moist mineral-soil site in southern Finland, planted with 1+1 bareroot stock in spring 1987: (a) no weed control treatment; (b) mulching with a fibre slurry produced by mixing wastepaper with water and applied 1 cm deep to an area of 60 cm in diameter around the seedling soon after planting; (c) glyphosate (at 2 kg ha-1) sprayed on a 1 m2 spot around the seedling in early August 1987; (d) terbuthylazine (at 10 kg ha-1) applied as (c). Monitoring of the trials over a 4-year period between 1987–90 showed that none of the treatments reduced surface vegetation to an extent that would have benefited pine. The percentage cover development of the vegetation, dominated by Agrostis capillaris, Calamagrostis arundinaceae, Deschampsia flexuosa, Festuca ovina, Epilobioum angustifolium and Pteridium aquillinum, followed much the same pattern in all treatments, with (c) slightly favouring forbs. Survival of pine at the end of the study period was about 90%, with non-significant differences between treatments. Mulching and terbuthylazine treatment slightly reduced seedling height growth in the second year. Growth was better in glyphosate treatment than in terbuthylazine treatment in the lowest (<30%) and the highest (>60%) pre-treatment weed cover classes, and in the latter also better than in untreated control. Mulching gave variable results; at its best it provided also good control of weeds for several years, without, however, improving the initial development of pine in these trials.

  • Siipilehto, ORCID ID:E-mail:
  • Lyly, ORCID ID:E-mail:
article id 5543, category Article
Matti Haapanen. (1995). Within-plot subsampling of trees for assessment in progeny trials of Scots pine. Silva Fennica vol. 29 no. 1 article id 5543. https://doi.org/10.14214/sf.a9194

Tree height data from 33 progeny trials of Scots pine (Pinus sylvestris L.) were used to determine the effect of within-plot subsampling on the magnitude of statistically detectable differences between families, family heritability and correlation of family means based on different sample sizes. The results indicated that in trials established with a standard plot configuration of 25 trees per plot, measuring only 10–15 trees gives nearly the same precision as with assessment of all the plot trees. Even as few as 4–6 trees assessed per plot may constitute a sufficient sample if families or parental trees of extreme performance are being selected. Trials established with non-contiguous plots were found to be more efficient than those established using multiple-tree contiguous plots.

  • Haapanen, ORCID ID:E-mail:
article id 5540, category Article
Anders Persson. (1994). How genotype and silviculture interact in forming timber properties. Silva Fennica vol. 28 no. 4 article id 5540. https://doi.org/10.14214/sf.a9180

Independent of genotype, increased spacing results in increased branch diameter of Scots pine (Pinus sylvestris L.), but on different levels for different genotypes. Frequency of defects like spike knots and crooked stems are under stronger genetic than silvicultural control. Simultaneous improvement of rate of growth and timber properties is feasible. Deteriorating of both factors can happen rapidly at a negative selection. A defect like stem cracking of Norway spruce (Picea abies (L.) H. Karst.) only manifests itself under drought stress when certain genetic and environmental prerequisites are present, like high fertility and wide spacing. This emphasize the fact that new silvicultural methods may reveal genetic weaknesses.

  • Persson, ORCID ID:E-mail:
article id 5530, category Article
Anna Saarsalmi, Erkki Lipas, Jouni Mikola, Teijo Nikkanen, Eira-Maija Savonen. (1994). Effect of fertilization on flowering and seed crop in Scots pine seed orchards. Silva Fennica vol. 28 no. 3 article id 5530. https://doi.org/10.14214/sf.a9170

The aim of the study was to obtain information needed in preparing more precise fertilization recommendations for seed orchards. The fertilization requirement was estimated on basis of soil and needle analyses, and by investigating the effects of different fertilization treatments on male and female flowering, size of seed crop and seed quality.

The study was carried out in two Scots pine (Pinus sylvestris L.) seed orchards in Southern Finland, one established on forest soil in 1971 and 1972, and the other on a peat field in 1974. 10 clones and 39 grafts from each clone were selected randomly from both orchards in autumn 1985. The treatments consisted of N, P and K in various combinations, micronutrients, wood ash and grass control. The orchards were fertilized in spring 1986.

There were statistically significant differences between the clones in both orchards as regards amount of flowers, size of the seed crop and seed quality. The annual variation in flowering and the size of the seed crop was also large. In general, the seeds from cones collected in October matured well and their germination percentage was high. The effects of fertilization on flowering, the size of seed crop and seed quality were small. It would appear that the size of the crop can be affected to a much greater extent by favouring clones with a high seed-producing capacity than through fertilization. Fertilization is unnecessary if the nutrient status of the soil is satisfactory.

  • Saarsalmi, ORCID ID:E-mail:
  • Lipas, ORCID ID:E-mail:
  • Mikola, ORCID ID:E-mail:
  • Nikkanen, ORCID ID:E-mail:
  • Savonen, ORCID ID:E-mail:
article id 5529, category Article
Jukka Lippu. (1994). Patterns of dry matter partitioning and 14C-photosynthate allocation in 1.5-year-old Scots pine seedlings. Silva Fennica vol. 28 no. 3 article id 5529. https://doi.org/10.14214/sf.a9169

Change in dry matter partitioning, 14C-incorporation, and sink 14C-activity of 1.5-year-old Scots pine (Pinus sylvestris L.) seedlings grown in growth chamber conditions were studied during a 91-day experiment. On five sampling dates, seedlings were labelled with 14CO2 and whole-plant allocation patterns were determined. Intensively growing shoots modified the dry matter partitioning: during shoot growth the proportion of roots decreased but after that it increased. Based on their large proportion of dry matter, the needles (excluding current needles) were the strongest sink of carbon containing 40% of the incorporated 14C. Despite their small initial sink size, the elongating shoots (current main shoot + current branch) and their needles were the second strongest sink (30–40% of the total 14C) which reflects their high physiological activity. The proportion of 14C in the current year’s main shoot increased during shoot growth but decreased as the growth began to decline after 70 days. 10–20% of the total assimilated 14C was translocated to the roots. Laterals above 2nd order were the strongest sink in the root system, containing twice as much 14C as the other roots together. Alternation between shoot and root growth can be seen clearly: carbon allocation to roots was relatively high before and after the period of intensive shoot growth. Changes in root sink strength resulted primarily from changes in root sink activity rather than sink size.

  • Lippu, ORCID ID:E-mail:
article id 5402, category Article
Risto Jalkanen, Juha Kaitera. (1994). Gremmeniella abietina produces pycnidia in cankers of living shoots with green needles on Scots pine. Silva Fennica vol. 28 no. 2 article id 5402. https://doi.org/10.14214/sf.a9168

A Gremmeniella abietina (Lagerb.) race of type A was found to produce pycnidia in cankers of previous year’s shoots (1991) on branches of Scots pine (Pinus sylvestris L.) bearing green needles and living buds in the current-year shoots (1992) with no apparent symptoms of infection by G. abietina. The restricted colonization of green shoots by G. abietina, with only restricted canker development, may indicate that older, slow-growing natural Scots pines of the northern boreal forests resists the fungus well. However, the ability of the fungus to survive and even sporulate in such cankers indicates one way of surviving over consecutive years otherwise unfavourable for it.

  • Jalkanen, ORCID ID:E-mail:
  • Kaitera, ORCID ID:E-mail:
article id 5397, category Article
Juha Kaitera, Risto Jalkanen. (1994). Old and fresh Gremmeniella abietina damage on Scots pine in eastern Lapland in 1992. Silva Fennica vol. 28 no. 2 article id 5397. https://doi.org/10.14214/sf.a9166

Damage on Scots pine (Pinus sylvestris L.) caused by Gremmeniella abietina (Lagerb.) Morelet was assessed in the summer of 1992 in 67 stands in eastern Lapland. The area and severity of damage were smaller and lighter than had earlier been estimated and occurred especially in stands in the first-thinning stage or in middle-age. Significant new infection of 1991 occurred in stands previously heavily infected by G. abietina near Kemihaara river, lake Naruska, the Naruska river, the Tuntsa river and lake Vilma. Fresh damage occurred mainly in the lower or middle parts of the Scots pine canopies.

  • Kaitera, ORCID ID:E-mail:
  • Jalkanen, ORCID ID:E-mail:
article id 5525, category Article
Jari Miina. (1994). Spatial growth model for Scots pine on drained peatland. Silva Fennica vol. 28 no. 1 article id 5525. https://doi.org/10.14214/sf.a9159

A spatial growth model is presented for Scots pine (Pinus sylvestris L.) on a dwarf-shrub pine mire drained 14 years earlier. The growth model accounts for the variation in tree diameter growth owing to the competition between trees, the distance between tree and ditch, and the time passed since drainage. The model was used to study the effect of tree arrangement on the post-drainage growth of a pine stand. Clustering of trees decreased the volume growth by 9–20% as compared to a regular spatial distribution. Stand volume growth, for a given number of stems, was at its maximum and variation in diameter growth at its minimum when the stand density on the ditch border was 1.5–5 higher than midway between two adjacent ditches.

  • Miina, ORCID ID:E-mail:
article id 5521, category Article
Taneli Kolström, Seppo Kellomäki. (1993). Tree survival in wildfires. Silva Fennica vol. 27 no. 4 article id 5521. https://doi.org/10.14214/sf.a15682

The survival of forest tree species in wildfires was examined on two burned stands. Norway spruce (Picea abies (L.) H. Karst.) and birches (Betula spp.) proved to be sensitive to the effects of wildfire; almost all individuals of these tree species were killed by the fires. Scots pine (Pinus sylvestris L.) was more tolerable to the effects of wildfire; i.e. one out of five Scots pines survived. Fire tolerance increased as tree size increased.

The PDF includes an abstract in Finnish.

  • Kolström, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
article id 5520, category Article
Kari T. Korhonen. (1993). Mixed estimation in calibration of volume functions of Scots pine. Silva Fennica vol. 27 no. 4 article id 5520. https://doi.org/10.14214/sf.a15681

Regression models for estimating stem volume of Scots pine (Pinus sylvestris L.) were constructed using sample tree data measured in the 7th and 8th National Forest Inventory of Finland. Stem volume were regressed on diameter, basal area of growing stock, and geographic location. The results of the study show that using second order trend surface to describe the geographic variation of the residuals gives satisfactory results. Using mixed estimation for combining old and new sample tree data improves the efficiency of an inventory. The weight of the prior information must be low, because remarkable differences in stem form was found in the two inventories.

The PDF includes an abstract in Finnish.

  • Korhonen, ORCID ID:E-mail:
article id 5518, category Article
Heikki Hänninen, Seppo Kellomäki, Kaisa Laitinen, Brita Pajari, Tapani Repo. (1993). Effect of increased winter temperature on the onset of height growth of Scots pine: a field test of a phenological model. Silva Fennica vol. 27 no. 4 article id 5518. https://doi.org/10.14214/sf.a15679

According to a recently presented hypothesis, the predicted climatic warming will cause height growth onset of trees during mild spells in winter and heavy frost damage during subsequent periods of frost in northern conditions. The hypothesis was based on computer simulations involving a model employing air temperature as the only environmental factor influencing height growth onset. In the present study, the model was tested in the case of eastern Finnish Scots pine (Pinus sylvestris L.) saplings. Four experimental saplings growing on their natural site were surrounded by transparent chambers in autumn 1990. The air temperature in the chambers was raised during the winter to present an extremely warm winter under the predicted conditions of a double level of atmospheric carbon dioxide. The temperature treatment hastened height growth onset by two months as compared to the control saplings, but not as much as expected on the basis of the previous simulation study. This finding suggests that 1) the model used in the simulation study needs to be developed further, either by modifying the modelled effect of air temperature or by introducing other environmental factors, and 2) the predicted climatic warming will not increase the risk of frost damage in trees as much as suggested by the previous simulation study.

The PDF includes an abstract in Finnish.

  • Hänninen, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Laitinen, ORCID ID:E-mail:
  • Pajari, ORCID ID:E-mail:
  • Repo, ORCID ID:E-mail:
article id 5513, category Article
Tapani Pöykkö, Pirkko Velling. (1993). Inheritance of the narrow-crowned Scots pine E 1101, "Kanerva pine". Silva Fennica vol. 27 no. 3 article id 5513. https://doi.org/10.14214/sf.a15674

There is some evidence to support the hypothesis that crown form of Scots pine (Pinus sylvestris L.) can be inherited either mono- or polygenically. In Finland, a narrow, horizontal whorl-layer structure is striking in about one half of the offspring of a genotype E 1101, ”Kanerva pine”. The offspring are characterized by a narrow crown, short and thin branches at an angle of 90° to the stem, minimal tapering and by numerous long, lateral shoots, long needles and the common occurrence of three-needled fascicles among the dwarf shoots. These features are connected to a high growth rate, a high harvest index and to tortuosity of the stem. It is suggested that this complex of characters is determined by a single dominant gene.

In this study, several offspring of the E 1101 were classified into three form types in seven sets of progeny test data, including progenies of various ages having E 1101 as either maternal or paternal parent as well as open pollinated progenies of second-generation offspring. A segregation close to 1:1 was found both in the first and in the second-generation progenies when wilds and intermediates were combined and compared with Kanervas. The result indicates that the three types of Kanerva form can be due to a single dominant allele (K). Kanervas are heterozygous (Kk) for the allele and wilds are recessive homozygotes (kk) resulting 1:1 segregation in their progenies. However, there were also remarkable deviations from the expected distribution. The differences as well as the inheritance pattern are discussed.

The PDF includes an abstract in Finnish.

  • Pöykkö, ORCID ID:E-mail:
  • Velling, ORCID ID:E-mail:
article id 5512, category Article
Christian Messier, Pasi Puttonen. (1993). Coniferous and non-coniferous fine-root and rhizome production in Scots pine stands using the ingrowth bag method. Silva Fennica vol. 27 no. 3 article id 5512. https://doi.org/10.14214/sf.a15673

Coniferous and non-coniferous fine root and rhizome production was measured after one growing season using the ingrowth bag method in Scots pine (Pinus sylvestris L.) stands differing in ages from 7 to 105 years in Southern Finland. Total fine-root production decreased from the 7-year to 20-year-old stands, and then increased slightly in the 85- to 105-year-old stands. Most of the total fine-root biomass in the youngest age groups came from non-conifer species, whereas most of the total fine-root biomass in the three older age groups came from conifer species. The maximum coniferous fine-root production was found to occur at crown closure in the 11- to 13-year-old stands. Rhizome production was the lowest and highest in the 20- and 85- to 105-year-old stands, respectively. The increase in rhizome production in the 85- to 105-year-old stands was associated with an abundant understory cover of Vaccinium myrtillus and V. vitis-idaea and an increase in light penetration. The ingrowth bag method was found to be useful in assessing the relative fine-root production among species-group and successional stages of Scots pine stands.

The PDF includes an abstract in Finnish.

  • Messier, ORCID ID:E-mail:
  • Puttonen, ORCID ID:E-mail:
article id 5510, category Article
Esa Koistinen, Sauli Valkonen. (1993). Models for height development of Norway spruce and Scots pine advance growth after release in southern Finland. Silva Fennica vol. 27 no. 3 article id 5510. https://doi.org/10.14214/sf.a15671

Mixed linear models were constructed to describe the height development of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) advance growth after release cutting. The models related density of the overstory, time elapsed since release cutting and tree size with annual height increment. Parameters of preliminary models were estimated from a limited data set to judge the feasibility of the approach for further studies.

The PDF includes an abstract in Finnish.

  • Koistinen, ORCID ID:E-mail:
  • Valkonen, ORCID ID:E-mail:
article id 5506, category Article
Risto Heikkilä, Sauli Härkönen. (1993). Moose (Alces alces L.) browsing in young Scots pine stands in relation to the characteristics of their winter habitats. Silva Fennica vol. 27 no. 2 article id 5506. https://doi.org/10.14214/sf.a15667

Moose (Alces alces L.) browsing was studied in young Scots pine (Pinus sylvestris L.) stands mixed with deciduous trees in high-density winter ranges. The proportional use of twig biomass decreased as the availability increased. The total as well as proportional biomass consumption were higher on the moist than on the dry type of forest. The per tree consumption of pine was higher on the moist type, where the availability of pine was lower. Deciduous trees were more consumed on the moist type, where their availability was relatively high. The consumption of pine saplings increased as the availability of birch increased. Pine stem breakages were most numerous when birch occurred as overgrowth above pine and at high birch densities. The availability of other deciduous tree species did not correlate with browsing intensity of Scots pine. Moose browsing had seriously inhibited the development of Scots pines in 6% of the stands, over 60% of available biomass having been removed. Rowan and aspen were commonly over-browsed and their height growth was inhibited, which occurred rarely by birch. There was no difference in the proportion of young stands in forest areas with high and low moose density. A high proportion of peatland forests was found to indicate relatively good feeding habitats in the high-density areas.

The PDF includes an abstract in Finnish.

  • Heikkilä, ORCID ID:E-mail:
  • Härkönen, ORCID ID:E-mail:
article id 5505, category Article
Heli Peltola, Jorma Aho, Alpo Hassinen, Seppo Kellomäki, Matti Lemettinen. (1993). Swaying of trees as caused by wind: analysis of field measurements. Silva Fennica vol. 27 no. 2 article id 5505. https://doi.org/10.14214/sf.a15666

Measurements of wind and subsequent swaying of two Scots pines (Pinus sylvestris L.) were made at stand edge conditions. The horizontal windspeed was measured ten meters outside of the stand edge for four heights using cup anemometers. The compass directions were determined using a directional vane placed above the canopy. Tree swaying was measured by accelerometers at xy-coordinates. The shape of the wind profile at the stand edge varied to some degree depending on windspeed, but the form was a logarithmic one. Swaying of trees increased along with increasing windspeed. Furthermore, swaying was more or less irregular in relation to xy-coordinates, but it occurred, however, mainly perpendicularly to the direction of mean windspeed. The maximum bending of trees to the direction of mean windspeed varied also only little for various gusting windspeeds (average windspeed of 20 seconds) and dynamic wind loads. The maximum bending of trees was also in most cases less or equal to those predicted on the basis of static wind loads, when the mean windspeed for static load is taken as equal to the gusting windspeed.

The PDF includes an abstract in Finnish.

  • Peltola, ORCID ID:E-mail:
  • Aho, ORCID ID:E-mail:
  • Hassinen, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Lemettinen, ORCID ID:E-mail:
article id 5504, category Article
Heli Peltola, Seppo Kellomäki. (1993). A mechanistic model for calculating windthrow and stem breakage of Scots pines at stand age. Silva Fennica vol. 27 no. 2 article id 5504. https://doi.org/10.14214/sf.a15665

A model for the mechanism of windfall and stem breakage was constructed for single Scots pine (Pinus sylvestris L.) at the stand edge. The total turning moment arising from the wind drag and from the bending of stem and crown was calculated along with the breaking stress of the stem. Similarly, the support given by the root -soil plate anchorage was calculated. Windspeed variation within the crown and the vertical distribution of stem and crown weight were taken into account. Model computations showed that trees having a large height to diameter ratio were subjected to greater risk of falling down or breaking than trees with a small height to diameter ratio. The windspeed required to blow down a tree or break the stem of a tree decreased if the height to diameter ratio or the crown to stem ratio of trees increased.
The PDF includes an abstract in Finnish.

  • Peltola, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
article id 7094, category Article
S. E. Multamäki. (1923). Tutkimuksia ojitettujen turvemaiden metsänkasvusta. Acta Forestalia Fennica vol. 27 no. 1 article id 7094. https://doi.org/10.14214/aff.7094
English title: Studies on the growth of drained peatlands in Finland.

Only about 24,000 hectares of peatlands have been drained in the state lands by the 1921. The aim of this study was to define how much the growth of the trees in the drained peatland revives. Sample plots were measured in previously drained peatlands that had sufficient Scots pine (Pinus sylvestris L.) tree stand. A stem analysis was performed to one of the sample trees. The evenness of the stands was dependent on how evenly the peatlands had dried when the stand was regenerated. Thus, the sample stands were not always fully stocked. However, they had capacity to develop towards evenly structured forests as the peatlands continued to dry further. The diameter and height growth of the dried peatlands have corresponded the similar stands in mineral soil sites. In trees that have grown stunted in the peatlands, the diameter growth seems to increase faster than the height growth. The volume growth is slightly smaller than in the similar mineral soil sites due to less favorable stem form. After the draining, the roots of the trees continued to grow from the old branches of root, but start then to form new roots. When the ground water level drops, the root layer grows deeper.

The PDF includes a summary in German.

  • Multamäki, ORCID ID:E-mail:
article id 5495, category Article
Hannu Salminen, Martti Varmola. (1993). Influence of initial spacing and planting design on the development of young Scots pine (Pinus sylvestris L.) stands. Silva Fennica vol. 27 no. 1 article id 5495. https://doi.org/10.14214/sf.a15656

Three Scots pine (Pinus sylvestris L.) plantations carrying 35 plots with initial spacings from 800 to 5,000 plants/ha were studied. Planting designs varied from a square to a rectangle with 5-metre row distance, the plant-to-plant distance being 0.8 metres. At current dominant height of 6 m, rectangularity had no effect on height, diameter, or volume growth of trees. Slight ovality of stems was observed in rectangular plots but the differences in the cross-wise mean diameters were very small, not over 1.1 mm in terms of plot-wise means. The diameter of the thickest living branch of a tree was linearly dependent of the dbh. The branches were clearly thicker between the planting rows at under 1,600 stems/ha stand density. A non-square planting pattern is a conceivable alternative when the line corridors suitable for mechanized silvicultural operations are preferred.
The PDF includes an abstract in Finnish.

  • Salminen, ORCID ID:E-mail:
  • Varmola, ORCID ID:E-mail:
article id 5494, category Article
Jari Nieppola. (1993). Site classification in Pinus sylvestris L. forests in southern Finland. Silva Fennica vol. 27 no. 1 article id 5494. https://doi.org/10.14214/sf.a15655

It was examined whether the present site classification method, and especially its applicability to site productivity estimation, could be improved in upland Scots pine (Pinus sylvestris L.) forests in Southern Finland by developing a classification key based on Two-way Indicator Species Analysis (TWINSPAN), and/or by inclusion of soil texture, stoniness and the humus layer depth more closely in the classification method. TWINSPAN clusters (TW) explained 71%, and forest site types (FST) 64% of the variation in site index (SI) (H100). When soil texture (TEXT) was added to the regression model, the explanatory power increased to 82% (SI = TW + TW * TEXT) and to 80% (SI = FST + FST * TEXT), respectively. Soil texture alone explained 69% of the variation in site index. The influence of stoniness on site index was significant (P <0.05) on sorted medium sand soils and on medium and fine sand moraine soils. The thickness of the humus layer (2–6 cm) was not significantly (P=0.1) related to site index.

It is suggested that the proposed TWINSPAN classification cannot replace the present forest site type system in Scots pine stands in Southern Finland. However, the TWINSPAN key may be used to aid the identification of forest types. The observation of dominant soil texture within each forest type is recommended.

The PDF includes an abstract in Finnish.

  • Nieppola, ORCID ID:E-mail:
article id 5490, category Article
Timo Pukkala, Jari Karsikko, Taneli Kolström. (1992). A spatial model for the diameter of thickest branch of Scots pine. Silva Fennica vol. 26 no. 4 article id 5490. https://doi.org/10.14214/sf.a15651

The model predicts the base diameter of the thickest living branch of a tree growing in a planted or naturally regenerated even-aged stand. A mixed model type was used in which the residual variation was divided into within-stand and between-stand components. The study material consisted of 779 trees measured in 12 plots located in 20 to 35 years old Scots pine (Pinus sylvestris L.) stands (breast height age 10 to 20 years). Branch diameter was closely connected to the breast height diameter of the stem. In a stand of a certain age, competition by close neighbours slightly decreased branch diameter in a given diameter class. According to the model, the greatest difference is between trees subjected to very little competition and those subjected to normal competition. The model was used in simulated stands with varying age, density, and tree arrangement. The simulations showed that trees with rapid diameter growth at young age had thicker branches at a given breast height diameter than trees with slower diameter growth. However, a very slow growth rate did not produce trees with branches thinner than those possessing a medium growth rate.
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  • Pukkala, ORCID ID:E-mail:
  • Karsikko, ORCID ID:E-mail:
  • Kolström, ORCID ID:E-mail:
article id 5488, category Article
Matti Haapanen. (1992). Effect of plot size and shape on the efficiency of progeny tests. Silva Fennica vol. 26 no. 4 article id 5488. https://doi.org/10.14214/sf.a15649

A simulation approach was applied to study the pattern of environmental variability and the relative statistical efficiency of 14 different plot types. The study material consisted of two nine-year-old field tests of Scots pine (Pinus sylvestris L.). The area of the test sites was 1.57 and 0.67 hectares. The efficiency was measured as the error variance attached to the estimate of family mean and the total size of a test needed to detect a given, least significant difference between two family means. The statistical efficiency tended to decline along with increasing plot size. The importance of plot shape was negligible compared to plot size. The highest efficiency was obtained with single-tree plots. Non-contiguous plots appeared to be considerably more efficient than block plots of equal size. The effects of intergenotypic competition on the choice of plot type are discussed.

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  • Haapanen, ORCID ID:E-mail:
article id 5487, category Article
Maarit Kytö. (1992). Lygus bugs as agents of growth disorders in permethrin-treated pine seedlings in regeneration areas. Silva Fennica vol. 26 no. 4 article id 5487. https://doi.org/10.14214/sf.a15648

The ability of Lygus bugs to cause growth disorders in permethrin-treated Scots pine (Pinus sylvestris L.) seedlings after planting was studied in two regeneration areas. There were three treatments: exposure of the seedlings to Lygus, mechanical protection of the seedlings from insects, and control seedlings. There were no significant differences in the rate of growth disorders between the treatments. The permethrin application protected the seedlings against Lygus bugs in the early summer, as well as when the bug abundance was low. The development of these seedlings, as well as the multiple-leadered and bushy seedlings on a third regeneration area, was followed for two years. Multiple leaders reduced height growth and bud number of a seedling, but caused marked losses in growth only when the seedlings still had multiple leaders the following year, or when they formed several, equally developed stems.
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  • Kytö, ORCID ID:E-mail:
article id 5486, category Article
Kari Löyttyniemi, Risto Heikkilä, Seppo Repo. (1992). Pine tar in preventing moose browsing. Silva Fennica vol. 26 no. 3 article id 5486. https://doi.org/10.14214/sf.a15647

The efficacy of pine tar as a moose (Alces alces L.) contact repellent was tested in young Scots pine (Pinus sylvestris L.) stands suffering from moose damage in Southern Finland during the winter 1981–82. Application of tar to shoots by spraying protected the trees satisfactorily throughout the winter.

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  • Löyttyniemi, ORCID ID:E-mail:
  • Heikkilä, ORCID ID:E-mail:
  • Repo, ORCID ID:E-mail:
article id 5483, category Article
Erkki Verkasalo. (1992). Relationships of the modulus of elasticity and the structure of Finnish Scots pine wood. Silva Fennica vol. 26 no. 3 article id 5483. https://doi.org/10.14214/sf.a15644

The paper presents preliminary results on the relationships of the longitudinal modulus of elasticity (E) in bending, based on ISO Standard 3349 tests on small, clear specimens, and some basic characteristics of Finnish Scots pine (Pinus sylvestris L.) wood. A manual image analysis method – quantitative stereological counting – was introduced and applied for the investigations of wood structure.

The main results were consistent with those from the prior research. The range of E was 9.7 to 19.1 GPa. Increase in especially fibre density index (R2 = 0.95), weight density and specific gravity (R2 = 0.90), Runkel’s ratio, coefficient of cell rigidity and number of growth rings per cross-sectional unit area, but also in latewood percentage (R2 = 0.58) resulted in an increase in E. Increase in growth ring width, particularly in the width of the late wood section within a ring (R2 = 0.63 to 0.90) had a reverse effect. Cell wall thickness did not show any clear effect. Except for tracheid diameter, the relationships were stronger for the variables determined in the tangential than in the radial wood direction.

Quantitative stereological counting has been used to some degree in the Finnish wood research. The procedure is technically feasible and easy to use. A large sample of counting areas is frequently needed to obtain accurate mean results for the size and distribution of the features. Because the actual analysis points are located at a fixed distance from each other, the method is not in principle well suited for wood with a regular and simple structure, as Scots pine. However, the good correlations between E and some characteristics obtained with stereological counting did not support this misgiving.

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  • Verkasalo, ORCID ID:E-mail:
article id 5482, category Article
Heljä-Sisko Helmisaari. (1992). Spatial and age-related variation in nutrient concentrations of Pinus sylvestris needles. Silva Fennica vol. 26 no. 3 article id 5482. https://doi.org/10.14214/sf.a15643

Spatial and age-related variation in nutrient concentrations of Scots pine (Pinus sylvestris L.) needles was studied during 1984–86 in three stands of different stages of development. The dry weight of current needles was significantly (p < 0.05) higher in the tree top than in a composite sample representing the whole crown. However, there were no significant differences in the concentrations of nutrients in needles between upper and lower crown levels. The concentrations of mobile nutrients N, P, K and Mg decreased with increasing needle age whereas the concentrations of poorly mobile nutrients Ca, Mn and Fe increased during needle ageing. The coefficient of variation for nutrient concentrations varied irregularly when only a few trees were sampled but stabilized when tree number was ten or more.
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  • Helmisaari, ORCID ID:E-mail:
article id 5481, category Article
Pekka Nygren, Pertti Hari. (1992). Effect of foliar application with acid mist on the photosynthesis of potassium-deficient Scots pine seedlings. Silva Fennica vol. 26 no. 3 article id 5481. https://doi.org/10.14214/sf.a15642

The interactive effects of potassium deficit and foliar application with acid water (pH 5.5, 4.5, 4.0 and 3.0 given consecutively) on CO2 exchange rate of Pinus sylvestris L. seedlings was investigated in field conditions. No reduction of the CO2 exchange rate was observed in the seedlings supplied with sufficient potassium. Only the seedlings having the lowest needle K concentration (2.4 mgg-1) had an apparently low CO2 exchange rate before the applications with acid water. The CO2 exchange rate of most of the seedlings with low needle K concentration (3.9–6.0 mgg-1) decreased after the acid water application. The threshold acidity for the reduction varied between pH 4,0 and 3.0 depending on the needle K concentration. The reduction was more apparent at high irradiance. It was concluded that acid precipitation disturbs the CO2 exchange only in conditions of mineral nutrient deficit.

The PDF includes an abstract in Finnish.

  • Nygren, ORCID ID:E-mail:
  • Hari, ORCID ID:E-mail:
article id 5478, category Article
Seppo Kellomäki, Marja Kolström. (1992). Computations on the management of seedling stands of Scots pine under the influence of changing climate in southern Finland. Silva Fennica vol. 26 no. 2 article id 5478. https://doi.org/10.14214/sf.a15639

Model computations on the management of Scots pine (Pinus sylvestris L.) at the seedling stage showed that a rising temperature due to the suggested climate change could increase the competition capacity of birch species (Betula pendula) more than Scots pine, whose growth could even decline during the course of a rise in temperature. A temperature rise could, thus, bring the time of removal of birches forward when aiming at Scots pine timber stands composed of these tree species. The increasing proportion of birches makes the removal of birches even more urgent and emphasizes the need for careful management of Scots pine stands under rising temperatures. The first thinning of Scots pine is generally brought forward; this is particularly the case when wide spacing is applied in planting. A furthrer rise in temperature magnifies the above patterns by reducing further the competitive capacity of Scots pine in relation to birches.
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  • Kellomäki, ORCID ID:E-mail:
  • Kolström, ORCID ID:E-mail:
article id 5476, category Article
Jukka Selander, Auli Immonen. (1992). Effect of fertilization and watering of Scots pine seedlings on the feeding preference of the pine weevil (Hylobius abietis L.). Silva Fennica vol. 26 no. 2 article id 5476. https://doi.org/10.14214/sf.a15637

Two-year-old containerized Scots pine (Pinus sylvestris L.) seedlings, raised under different fertilization and watering regimes, were subjected to feeding preference tests with pine weevils (Hylobius abietis L.) in a bioassay. In the tests carried out with pairs of seedlings, the weevil preferred water-stressed seedlings to well-watered ones. In the case of well-watered seedlings, the weevil caused significantly more damage to NPK-fertilized seedlings than those given pure PK fertilization, or no fertilization at all. It is apparent that PK fertilization reduces, and water stress increases seedling susceptibility to weevil damage. The results support findings from field trials that water stress (planting shock) predisposes seedlings to weevil damage. Weevil resistance is discussed with respect to fertilization and water stress as determinants of seedling quality.

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  • Selander, ORCID ID:E-mail:
  • Immonen, ORCID ID:E-mail:
article id 5475, category Article
Jyrki Hytönen. (1992). Allelopathic potential of peatland plant species on germination and early seedling growth of Scots pine, silver birch and downy birch. Silva Fennica vol. 26 no. 2 article id 5475. https://doi.org/10.14214/sf.a15636

The potential alleopathic inhibitive effects of aqueous extracts of 13 peatland plant species on germination, radicle and seedling growth of Scots pine (Pinus sylvestris L.), silver and downy birch (Betula pendula Roth., B. pubescens Ehrh.) were studied. Freshly cut plant parts were finely ground, mixed with distilled water and agitated. The proportions of fresh plant mass in the mass-based extracts varied within the range of 1, 5, 10 and 20% (w/w). The seeds were germinated in petri dishes moistened with the plant extracts. In a separate experiment growth of birch seedlings irrigated with the extracts was studied.

Ledum palustre, Vaccinium uliginosum and Empetrum nigrum extracts, and in certain experiments extracts of other species, inhibited the germination of Scots pine and birch seeds. Results from the different experiments were not, however, fully consistent. None of the low (1% w/w) extract concentrations had any effect on germination. Strong extract concentrations (20% w/w) inhibited germination of pine seedlings significantly. The extracts affected only slightly the growth of potted birch seedlings.

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  • Hytönen, ORCID ID:E-mail:
article id 5469, category Article
Risto Heikkilä, Kari Löyttyniemi. (1992). Growth response of young Scots pines to artificial shoot breaking simulating moose damage. Silva Fennica vol. 26 no. 1 article id 5469. https://doi.org/10.14214/sf.a15627

The main stem of young Scots pine (Pinus sylvestris L.) trees was cut off halfway along the current leading shoot and the two previous years’ leading shoots to simulate moose (Alces alces) damage. Trees of the same size were chosen as controls before treatments. The experiment was inspected ten years after artificial stem breakage. Removing the current leading shoot and the second shoot did not essentially affect the height and diameter growth of the trees. Removal down to the third shoot reduced the height as well as diameter growth. The average loss in growth was equivalent to less than one year’s growth. When the stem was cut off at the second or third shoot, stem crookedness and the presence of knots resulted in stem defects that will subsequently reduce the sawtimber quality. A high proportion of the stem defects will obviously still be visible at the first thinning cutting. Removing injured trees as pulpwood and pruning the remaining parts of cut stems evidently improves the quality of pine stand with moose damage.

The PDF includes an abstract in Finnish.

  • Heikkilä, ORCID ID:E-mail:
  • Löyttyniemi, ORCID ID:E-mail:
article id 5463, category Article
Öje Danell. (1991). Survey of past, current and future Swedish forest tree breeding. Silva Fennica vol. 25 no. 4 article id 5463. https://doi.org/10.14214/sf.a15621

The paper gives an introduction of the tree breeding program of Sweden that started in 1936 by the establishment of an association for the tree breeding. In 1967 the Institute of Forest Improvement was founded and it replaced the earlier association. The main species in the programme have been Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), lately also birch (mainly Betula pendula Roth.) and lodgepole pine (Pinus contorta). In addition, limited breeding has been done also with hybrid aspen (Populus tremula x P. tremuloides), oak (Quercus), larch (Larix), black spruce (Picea mariana) and a few other native and exotic species. The dominating initial effort has been to select plustrees in natural stands and use them for production of reforestation material. In addition, a considerable body of tests was built. The paper lists the status of breeding material of the different tree species and introduces the medium and short-term breeding programmes.

  • Danell, ORCID ID:E-mail:
article id 5446, category Article
Hannu Ilvesniemi. (1991). Spatial and temporal variation of soil chemical characteristics in pine sites in Southern Finland. Silva Fennica vol. 25 no. 2 article id 5446. https://doi.org/10.14214/sf.a15600

In producing time series of soil properties, there are many technical and statistical problems which need to be taken into account when sampling and analysing the measurement data. In field the reliable localization of sample plots and the precise distinction of different soil layers are important to reduce the variance caused by the sampling procedure. In laboratory the use of same extraction salt, sample pretreatment procedure and filter paper throughout a measurement series is important. The remarkable small-scale variation within a sampling plot leads to a need of a large number of samples to be collected.

In this study, no trends attributable to soil acidification in the contents of exchangeable base cations could be found among the years 1982, 1985 and 1988. However, in eluvial and illuvial layers the pH decreased and the content of extractable H+ increased during this period. In illuvial layer also the content of extractable aluminium increased.

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  • Ilvesniemi, ORCID ID:E-mail:
article id 5443, category Article
Raimo Silvennoinen, Rauno Hämäläinen, Kaarlo Nygrén, Kim von Weissenberg. (1991). Spectroradiometric characteristics of Scots pine and intensity of moose browsing. Silva Fennica vol. 25 no. 2 article id 5443. https://doi.org/10.14214/sf.a15597

The light reflected from the crowns of Scots pine (Pinus sylvestris L.) clones was measured spectroradiometrically during and after growing season. Standard deviations of the spectra of pine clones showing differences in moose browsing intensity were compared. A new algorithm was developed for predicting the browsing intensity of moose (Alces alces).

The PDF includes an abstract in Finnish.

  • Silvennoinen, ORCID ID:E-mail:
  • Hämäläinen, ORCID ID:E-mail:
  • Nygrén, ORCID ID:E-mail:
  • Weissenberg, ORCID ID:E-mail:
article id 5438, category Article
Juha Heiskanen, Hannu Raitio. (1991). Maan vesipotentiaali paljasjuuristen männyntaimien taimitarhakasvatuksessa. Silva Fennica vol. 25 no. 1 article id 5438. https://doi.org/10.14214/sf.a15592
English title: Soil water potential during the production of bare-rooted Scots pine seedlings.

The matrix potential, measured with tensiometers, and its effect on the soil air-water ratio were examined during the production of bare-rooted Scots pine (Pinus sylvestris L.) seedlings in nursery fields. Soil water potential was monitored during the growing season of 1983 at three nurseries in Finland, and from fields growing various seedling types at depths of 10 and 20 cm. In 1986, soil core samples were collected in order to assess the water desorption characteristics of the soil. In addition, the effect of polypropylene gauze covering (Agryl P 17) on the soil water potential was examined during the growing season of 1985 at two nurseries in Finland at depths of 5, 10 and 15 cm.

The soil water potential was relatively high in all the fields studied. In fields growing one- and two-year-old seedlings, the median potential was higher than -10 kPa. The potential did not fall below the limit of the measured scale (ca. -85 kPa) of the tensiometers. Soil aeriation may have been periodically insufficient in the rooting zone, as a result of high water content. The favourable water potential is below -5 to – 6 kPa. The gauze covering slightly (1–4 kPa) increased the soil water potential, an effect which could be harmful if the soil air space is low. During the second growing season, the soil water potential was lower in the fields covered by the gauze during the first year than in the fields without the covering.

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  • Heiskanen, ORCID ID:E-mail:
  • Raitio, ORCID ID:E-mail:
article id 5437, category Article
Tapani Repo. (1991). Rehardening potential of Scots pine seedlings during dehardening. Silva Fennica vol. 25 no. 1 article id 5437. https://doi.org/10.14214/sf.a15591

The ability of one-year old Scots pine (Pinus sylvestris L.) seedlings to reharden during the dehardening period was studied. Naturally hardened quiescent seedlings were preconditioned at 0°C for ten days and then placed in chambers at different forcing temperatures with different light regimes. The forcing periods were followed by cool periods. Changes in frost hardiness were monitored at intervals using freeze tests of whole plants. Frost hardiness was assessed by three methods: impedance, survival and growth retardation. Dehardening seemed to be a partially reversible process, i.e. in some growing conditions slight rehardening was found.

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  • Repo, ORCID ID:E-mail:
article id 5436, category Article
Leena Finér. (1991). Root biomass on an ombrotrophic pine bog and the effects of PK and NPK fertilization. Silva Fennica vol. 25 no. 1 article id 5436. https://doi.org/10.14214/sf.a15590

Scots pine (Pinus sylvestris L.) living root biomass (ø≤ 10 mm) was 640 g/m2 on the studied low-shrub pine bog before fertilization, and that of the ground vegetation almost the same. The total root necromass was 23% of the biomass of living roots. The length of the pine roots was 2,440 m/m2. The biomass of living roots and root necromass were mostly located in the top 20 cm layer of the soil. The ø < 1 mm pine root fraction accounted for almost 90% of the pine root length; in contrast, over 50% of the biomass was in the 1–10 mm thick root biomass, pine root length and PK (MgB) fertilization did not affect total living root biomass, pine root length, nor the root necromass during the three-year observation period.

The PDF includes an abstract in Finnish.

  • Finér, ORCID ID:E-mail:
article id 5434, category Article
Risto Heikkilä. (1990). Effect of plantation characteristics on moose browsing on Scots pine. Silva Fennica vol. 24 no. 4 article id 5434. https://doi.org/10.14214/sf.a15588

The effects of plantation characteristics on moose (Alces alces) browsing intensity was studied in 82 Scots pine (Pinus sylvestris L.) plantations in Southern Finland. Moose browsing occurred most commonly in plantations established on relatively fertile soil, and the degree of damage was at highest in plantations with openings. A high amount of brush, especially aspen, increased the risk of damage. Furthermore, damage was intensified in plantations situated on hills, slopes or at a long distance from main roads or settlements.

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  • Heikkilä, ORCID ID:E-mail:
article id 5433, category Article
Marja-Leena Valkonen, Heikki Hänninen, Paavo Pelkonen, Tapani Repo. (1990). Frost hardiness of Scots pine seedlings during dormancy. Silva Fennica vol. 24 no. 4 article id 5433. https://doi.org/10.14214/sf.a15587

The relationships between bud dormancy and frost hardiness were examined using two-year-old Pinus sylvestris L. seedlings. The chilling temperatures used were +4 and -2°C. To examine the dormancy release of the seedlings, a forcing technique was used. Frost hardiness was determined by artificial freezing treatments and measurements of electrical impedance. At the start of the experiment, the frost hardiness of the seedlings was about -25°C. After the rest break, the seedlings kept at +4°C dehardened until after eight weeks their frost hardiness reached -5°C. At the lower chilling temperature (-2°C) the frost hardiness remained at the original level. When moved from +4 to -2°C, seedlings were able to reharden only after the time required for bud burst in the forcing conditions had reached the minimum.

The PDF includes an abstract in Finnish

  • Valkonen, ORCID ID:E-mail:
  • Hänninen, ORCID ID:E-mail:
  • Pelkonen, ORCID ID:E-mail:
  • Repo, ORCID ID:E-mail:
article id 5432, category Article
Risto Rikala, Helen J. Jozefek. (1990). Effect of dolomite lime and wood ash on peat substrate and development of tree seedlings. Silva Fennica vol. 24 no. 4 article id 5432. https://doi.org/10.14214/sf.a15586

Effect of dolomite lime and wood ash (0, 0.5, 1, 2, 4, 8 and 16 kg m-3) on the chemical composition of low humified Sphagnum peat was studied. Germination of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and silver birch (Betula pendula Roth) and the subsequent growth of these seedlings were investigated in a greenhouse experiment. Nutrient concentrations in shoots and roots of pine seedlings were also analysed. The pH of peat increased asymptotically from 3.8 to about 7.0 with increasing lime regimen and to about 8.0 with increasing ash regimen. Wood ash linearly increased electrical conductivity and P, K, and Ca concentrations of peat. Rate of germination, within 7 days, of pine and spruce was best at low pH (<5) while birch seeds had a slightly higher pH optimum (4–6). Germination capacity, within 21 days, was not affected by pH or application regimen of either lime or ash. Pine and spruce seedlings grew best with lime and ash doses of 0.5–2.0 kg m-3, the pH of peat being 4–5. Lime and ash treatments did not affect the growth of birch seedlings, but wood ash increased nutrient concentration of pine seedlings.

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  • Rikala, ORCID ID:E-mail:
  • Jozefek, ORCID ID:E-mail:
article id 5420, category Article
Toyohiro Miyazava, Jukka Laine. (1990). Effect of macroclimate on the development of Scots pine seedling stands on drained oligotrophic pine mires. Silva Fennica vol. 24 no. 2 article id 5420. https://doi.org/10.14214/sf.a15574

The influence of different fertilization treatments and ditch spacings on the height growth of young Scots pine (Pinus sylvestris L.) seedling stands growing under various climatic regimes were determined. Comparisons were made between naturally regenerated and planted seedling stands. The effective temperature sum had a stronger effect on the height growth of planted seedlings, and in Northern Finland the planted seedlings seemed to be influenced to a greater degree by the adverse climatic conditions. The heavier the dose of fertilizer that had been applied, the greater the difference in growth caused by macroclimate. A considerably larger proportion of natural seedlings were located on hummocks compared with that of planted seedlings, irrespective of the region. On plots with wider ditch spacings, seedlings growing on hummocks were superior in height growth to those on flat surfaces.

The PDF includes an abstract in Finnish.

  • Miyazava, ORCID ID:E-mail:
  • Laine, ORCID ID:E-mail:
article id 5414, category Article
Heikki Smolander, Seppo Kellomäki, Pauline Oker-Blom. (1990). Typpipitoisuuden vaikutus männyn neulasten fotosynteesiin ja verson itsevarjostukseen. Silva Fennica vol. 24 no. 1 article id 5414. https://doi.org/10.14214/sf.a15566
English title: The effect of nitrogen concentration on needle photosynthesis and within shoot shading in Scots pine.

A close relationship between photosynthetic capacity and nitrogen concentration of leaves is known to exist. In conifers, nitrogen also affects the pattern of mutual shading within a shoot, which is a basic unit used in studying photosynthesis of coniferous trees. These effects of needle nitrogen concentration on photosynthetic capacity and mutual shading of needles were analysed for Scots pine (Pinus sylvestris L.) shoots taken from five young stands growing on sites of different fertility. The effect of nitrogen concentration on needle photosynthesis was studied based on measurements of the photosynthetic radiation response of shoots from which two thirds of the needles were removed in order to eliminate the effect of within shading.

An increase of one percentage unit in nitrogen concentration of needles increased the photosynthetic capacity of needles by 25 mg CO2 dm-2h-1. The effect of nitrogen on within-shoot shading was quantified in terms of the silhouette area to total needle area ratio of a shoot (STAR), which determines the relative interception rate per unit of needle area on the shoot. Although nitrogen promoted needle growth, an increase in nitrogen concentration decreased the within-shoot shading. This effect resulted from a decrease in needle density on the shoot and an increased needle angle with increasing nitrogen content.

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  • Smolander, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Oker-Blom, ORCID ID:E-mail:
article id 5411, category Article
Eero Paavilainen. (1990). Effect of refertilization of pine and birch stands on a drained fertile mire. Silva Fennica vol. 24 no. 1 article id 5411. https://doi.org/10.14214/sf.a15563

Refertilization with PK, about 15 years after the first fertilizer application, increased tree growth and the amount of nutrients in tree litter in Scots pine (Pinus sylvestris L.) and birch (mainly Betula pubescens Erhr.) stands on a drained fertile mire in Northern Finland (65°34 N’, 25°42’ E). The increase in growth and nutrient contents after refertilization was greatest in the mature pine stand where the application of nitrogen and micronutrients gave an additional response compared to the PK-application.

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  • Paavilainen, ORCID ID:E-mail:
article id 5410, category Article
Markku Nygren. (1990). Männyn ja kuusen siementen massan vaihtelusta. Silva Fennica vol. 24 no. 1 article id 5410. https://doi.org/10.14214/sf.a15562
English title: Variation in the seed mass of Scots pine and Norway spruce.

Seed mass within any plant species is one of the least plastic components of plant structure. The aim of this study was to analyse the variation in the seed mass of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) in relation to three environmental factors: soil fertility, mean temperature and precipitation during seed filling period. Data published earlier on seed mass of these species on different sites and different years was used in the study.

The seed mass of both species was independent of soil fertility (forest type) but did vary between different years. It is hypothesized that if the seed-ripening summer is warmer than average, Scots pine seed mass tends to be smaller. In this study, seed mass varied independently of the amount of precipitation during the ripening summer. However, generalization of the results requires further study.

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  • Nygren, ORCID ID:E-mail:
article id 5406, category Article
Olavi Huuri. (1990). Leikattu paakkutaimi. Silva Fennica vol. 24 no. 1 article id 5406. https://doi.org/10.14214/sf.a15558
English title: The cut-block method for seedling production: birth of an idea.

The author first introduced the cut-block seedling production method to Finland in 1969. The aim is to raise seedlings whose lateral roots do not become deformed as a result of a restricting container or other external pressure. The seedlings are raised in a large, fairly compact substrate block where the roots can freely develop in a normal fashion. The blocks are then cut up into individual cubes, each containing a seedling. The precise positioning of the sowing point permits mechanization of the work.

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  • Huuri, ORCID ID:E-mail:
article id 5395, category Article
Mirja Kortesharju, Jouko Kortesharju. (1989). Studies on epiphytic lichens and pine bark in the vicinity of a cement works in northern Finland. Silva Fennica vol. 23 no. 4 article id 5395. https://doi.org/10.14214/sf.a15553

The element content (Ca, Mg, K, Na, Fe, Mn, Zn, Cu, Pb, S) of Scots pine (Pinus sylvestris L.) bark and Bryoria lichens, as well as the occurrence and coverage of epiphytic lichens and the length of Bryoria species, were studied in the vicinity of Kolari cement works, NW Finland. Fruticose Bryoria species had the highest coverage on pine trunks at a distance of 2 km or more from the cement works. At a distance of 1 km the foliose – or even crustose – Parmeliopsis species were most abundant, while nearer to the works lichens were almost completely absent. The length of Bryoria was reduced at distances of less than 2 km from the cement works. The calcium content in Bryoria species increased very steeply close to the works; by a factor of 60 at a distance of 1 km compared to 16 km. No corresponding increase in other elements was observed near the cement works. All the elements studied in pine bark showed a significant negative correlation with distance, and a significant positive correlation with the calculated dust deposition levels. There were only minor differences between the north and south of the pine trunks, or the side facing or away from the works. Pine bark analysis is recommended for element accumulation studies.

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  • Kortesharju, ORCID ID:E-mail:
  • Kortesharju, ORCID ID:E-mail:
article id 5391, category Article
Jukka Pietilä. (1989). Shape of Scots pine knots close to the stem pith. Silva Fennica vol. 23 no. 4 article id 5391. https://doi.org/10.14214/sf.a15549

The shape of Scots pine (Pinus sylvestris L.) knots close to the pith of butt logs was investigated. 1,100 knots were split in a vertical direction, and their shape was measured. Knot diameter and branch angle were calculated at a distance of 40 mm from the pith of the stem. The mean diameter of all the knots in the material was 14 mm, and the branch angle 70°. Regression analysis was used to devise a formula for predicting branch angle on the basis of knot diameter. Knot size and branch angle were negatively correlated. Especially the shape of larger knots was curved. Knots achieved their maximum diameter at distance of 4–5 cm from the stem pith. The branch wood was almost completely situated above the formation point of the branch.

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  • Pietilä, ORCID ID:E-mail:
article id 5390, category Article
Kari Heliövaara, Kari Löyttyniemi. (1989). Effect of forest fertilization on pine needle-feeding Coleoptera. Silva Fennica vol. 23 no. 4 article id 5390. https://doi.org/10.14214/sf.a15548

The effects of forest fertilizers on the intensity of damage caused by two curculionid (Brachyderes incanus L., Brachonyx pineti Paykull) and two chrysomelid (Calomicrus pinicola Duft., Cryptocephalus pini L.) species feeding as adults on Scots pine (Pinus sylvestris L.) needles were investigated in two pine stands growing on dry (Calluna type) sites in South-West Finland. There was much variation in the abundance of the insect species both between the trials and the sample plots. Nitrogen fertilization increased both the height and radial growth of the pines. The curculinids were slightly more abundant on the nitrogen-treated plots. Potassium application seemed to decrease the feeding intensity of the chrysomelids especially. The overall effects were so small that forest fertilization cannot be considered as an effective control method against needle-feeding beetles.

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  • Heliövaara, ORCID ID:E-mail:
  • Löyttyniemi, ORCID ID:E-mail:
article id 5389, category Article
Jyrki Tomminen, Matti Nuorteva, Markku Pulkkinen, Jouni Väkevä. (1989). Occurrence of the nematode Bursaphelenchus mucronatus Mamiya & Enda 1979 (Nematoda: Aphelenchoididae) in Finland. Silva Fennica vol. 23 no. 4 article id 5389. https://doi.org/10.14214/sf.a15547

A survey was conducted in Finland in 1988 to determine whether the pine wood nematode Bursaphelenchus mucronatus Mamiya & Enda 1979 (Nematoda: Aphelenchoididae) or the closely related species B. mucronatus would occur in Finnish forests. Dead or dying standing trees and timber of two conicer species, Pinus sylvestris L. (Scots pine) and Picea abies (L.) H. Karst. (Norway spruce) were analysed for the presence of these nematodes. Monochamus spp. pine sawyers (Coleoptera: Cerambycidae) were also collected and inspected for the presence of dispersal fourth juvenile stages (dauerlarva) of the nematodes. The species B. xylophilus was not found, but B. mucronatus appeared to be widespread in the country. Individuals of this nematode were found both from Scots pine and Norway spruce. Adults of two Monochamus species were found, M. galloprovincialis and M. sutor. Only two of the examined beetles of the former species had dauerlarvae in their body.

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  • Tomminen, ORCID ID:E-mail:
  • Nuorteva, ORCID ID:E-mail:
  • Pulkkinen, ORCID ID:E-mail:
  • Väkevä, ORCID ID:E-mail:
article id 5388, category Article
Martti Varmola. (1989). Männyn istutustaimikoiden lustonleveysmalli. Silva Fennica vol. 23 no. 4 article id 5388. https://doi.org/10.14214/sf.a15546
English title: A model for ring width of planted Scots pine.

Ring width at breast height is presented as a function of stem radius at breast height, the ratio between the diameter of a tree and the basal area median diameter, site index, and density of stand. By means of a conversion model ring width at stump height can be estimated as a function of ring width at breast height.

According to previous studies substantially better wood quality can be expected if mean width near the pith at stump height decreases from 3 to 2 mm. According to the present study only on the poorest sites suitable for Scots pine (Pinus sylvestris L.) planting (poor Vaccinium type) the ring width is less than 3 mm at stump height even in the thickest trees. On more fertile sites a substantial increase in the recommended planting density is required, if the mean ring width is aimed to be less than 3 mm. On the best sites it is impossible to reach mean ring width of less than 2 mm, when the density is less than 4,000 stems/ha. Only the thinnest trees on the poorest sites can have a mean ring width less than 2mm.

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  • Varmola, ORCID ID:E-mail:
article id 5385, category Article
Timo Kuuluvainen. (1989). Branching dynamics in young Scots pine. Silva Fennica vol. 23 no. 3 article id 5385. https://doi.org/10.14214/sf.a15542

The development of shoot number and shoot properties was examined in successive shoot cohorts of young widely-spaced Scots pine trees (Pinus sylvestris L.) growing in a progeny trial. This was accomplished by reconstructing the branching process of the trees over a period of five years, from tree age 4 to 8. During this time the number of shoots in successive shoot cohorts increased rapidly, while at the same time the mean shoot length decreased. The decrease in shoot lengths from older to younger shoots was accompanied by a decline in the bifuraction frequency of the shoots. In general, rapid changes occurred in the branching characteristics during the yearly development of the trees. The variation in the branching characteristics was reflected in the development of the architecture and biomass production of the trees.

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  • Kuuluvainen, ORCID ID:E-mail:
article id 5384, category Article
Raija-Liisa Petäistö. (1989). Syyskoulinnan ajankohdan vaikutus männyn taimien kuiva-ainepitoisuuteen, neulasten pitolujuuteen ja juurten uudistumiskykyyn. Silva Fennica vol. 23 no. 3 article id 5384. https://doi.org/10.14214/sf.a15541
English title: The influence of autumn transplanting date on the dry matter content, needle retention values and root regeneration of Scots pine (Pinus sylvestris) seedlings.

The experiment was performed in 1982–85 at the forest tree nursery in Suonenjoki, Central Finland. There were four to five transplanting dates ranging from the beginning of August to the end of September. The dry matter content, root regeneration and needle retention value of Scots pine (Pinus sylvestris L.) seedlings were examined. Development of the needle retention value in autumn was followed in nurseries at Suonenjoki, Rantasalmi, Mäntyharju and Taavetti in 1982.

Root regeneration was usually the worse, the later the seedlings were transplanted in the autumn. The dry matter content was generally lowest in the seedlings transplanted later in the autumn, and also to some extent in the seedlings transplanted at the beginning of August. The needle retention value increased as autumn advanced. Early transplanting in autumn had an adverse effect on the development of needle retention, and the values were highest in the seedlings transplanted later in the autumn.

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  • Petäistö, ORCID ID:E-mail:
article id 5382, category Article
Seppo Kellomäki, Taneli Kolström, Hannu Väisänen, Esko Valtonen. (1989). Simulations on the occurrence of dead trees in natural pine stands. Silva Fennica vol. 23 no. 3 article id 5382. https://doi.org/10.14214/sf.a15539

The study aimed at recognizing the phases of forest succession where dead trees most probably occur. The model simulations showed that the increasing occurrence of dead trees culminated after the canopy closure. Thereafter the occurrence of dead trees decreased representing a pattern where high frequency of dead trees was followed by low frequency of dead trees, the intervals between the peaks in the number of dead trees being in Southern Finland about 15–30 years. Around this long-term variation there was a short-term variation, the interval between the peaks in the number of dead trees being 2–4 years. This pattern was associated with the exhausting and release of resources controlled by the growth and death of trees.

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  • Kellomäki, ORCID ID:E-mail:
  • Kolström, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:
  • Valtonen, ORCID ID:E-mail:
article id 5379, category Article
Timo Kuuluvainen, Timo Pukkala. (1989). Effect of Scots pine seed trees on the density of ground vegetation and tree seedlings. Silva Fennica vol. 23 no. 2 article id 5379. https://doi.org/10.14214/sf.a15536

The study uses the methodology of ecological field theory to model the effect of Scots pine (Pinus sylvestris L.) seed trees on the density of tree seedlings and other plants in the field layer. The seed trees had a clear effect on the expected value of the amount and distribution of the ground vegetation. The vicinity of seed trees had an adverse effect on the growth of grasses, herbs and seedlings, while mosses were most abundant near the trees. Models based on the ecological field approach were derived to describe the effect of seed trees on the ground vegetation.

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  • Kuuluvainen, ORCID ID:E-mail:
  • Pukkala, ORCID ID:E-mail:
article id 5378, category Article
Jukka Pietilä. (1989). Factors affecting the healing-over of pruned Scots pine knots. Silva Fennica vol. 23 no. 2 article id 5378. https://doi.org/10.14214/sf.a15535

The material of the study consisted of 21 Scots pine (Pinus sylvestris L.) trees that had been pruned in the 1930’s and 1940’s. The butt log of the pruned stems was peeled into veneer from which the length and shape of the resin taps were determined. The length of the resin tap was affected in the first place by the knot diameter and the height of the knot along the stem. The length of the resin tap was about 1.5-fold that of the knot diameter. With an increase in the height above the ground of a knot, its length decreases. The resin taps were particularly long on poor sites and in the butt end of the stems, however, the variation in tap length was large both within and between the individual tree stands. The shape of the resin taps is presented in this study by diameter classes. The resin taps studied in the work were longer than those measured in other works. This may be due to the fact that the knots were uncovered by peeling instead of sawing.

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  • Pietilä, ORCID ID:E-mail:
article id 5376, category Article
Timo Pukkala. (1989). Predicting diameter growth in even-aged Scots pine stands with a spatial and non-spatial model. Silva Fennica vol. 23 no. 2 article id 5376. https://doi.org/10.14214/sf.a15533

The single tree growth models presented in this study were based on about 4,000 trees measured in 50 even-aged Scots pine (Pinus sylvestris L.) sample plots with varying density, spatial pattern of trees and stand age. Predictors that used information about tree locations decreased the relative standard error of estimate by 10 percentage points (15%), if past growth was not used as a predictor, and about 15 percentage points (30%) when past growth was one of the predictors. When ranked according to the degree of determination, the best growth models were obtained for the basal area increment, the next best for relative growth, and the poorest for diameter increment. The past growth decreased the relative standard error of estimate by 15–20 percentage points, but did not make the spatial predictors unnecessary. The degree of determination of the spatial basal area growth model was almost 80% if the past growth was unknown and almost 90% if the past growth was known. Variables that described the amount of removed competition did not improve the growth models.

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  • Pukkala, ORCID ID:E-mail:
article id 5375, category Article
Timo Pukkala. (1989). Prediction of tree diameter and height in a Scots pine stand as a function of the spatial pattern of trees. Silva Fennica vol. 23 no. 2 article id 5375. https://doi.org/10.14214/sf.a15532

The study presents two methods of predicting tree dimensions in a Scots pine (Pinus sylvestris L.) stand if only the location of trees is known. The first method predicts the tree diameter from the spatial location of neighbours. In the second method the diameter distribution of a subarea is estimated from the local stand density. This distribution is then sampled to obtain diameters. In both methods the tree height is predicted with a spatial model on the basis of diameters and locations of trees. The main purpose of the presented models is to generate realistic stands for simulation studies.

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  • Pukkala, ORCID ID:E-mail:
article id 5371, category Article
Riitta Laurila. (1989). Pieniläpimittaisen männyn kuituominaisuudet. Silva Fennica vol. 23 no. 1 article id 5371. https://doi.org/10.14214/sf.a15530
English title: Fibre properties in Pinus sylvestris pulpwood.

Properties of fibres in pulpwood, especially length, width and the thickness of walls in tracheids, are essential for strength properties of pulp and paper. Length and width of tracheids increase from pith to surface in radial direction. Young and small-sized stems have also smaller fibres. Small-sized Pinus sylvestris L. test trees had tracheids that were shorter both in stems and knot wood than those in normal sized trees. However, cell walls in test trees were as thick as in normal sized trees. It seems that especially the L/T -ratio (length/thickness) in small stems is worse than in normal sized pulp wood.

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  • Laurila, ORCID ID:E-mail:
article id 5368, category Article
Kari Heliövaara, Rauno Väisänen. (1989). Invertebrates of young Scots pine stands near the industrial town of Harjavalta, Finland. Silva Fennica vol. 23 no. 1 article id 5368. https://doi.org/10.14214/sf.a15527

Invertebrates of young Scots pine (Pinus sylvestris L.) stands were preliminarily studied along a gradient of industrial air pollutants in Harjavalta, south-western Finland. Bark samples and net samples on pine branches and needles were taken in May–June, 1987. The number of aphids on needles was highest near the industrial plants. The number of mites in bark was positively correlated with the increasing distance from the pollutant source. Detrended correspondence analysis ordination calculated according to the bark invertebrates showed that the sampling sites of the zones far from the emission source formed a distinct group while those of the zones near the source were relatively widely dispersed indicating disturbances in faunal structure.

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  • Heliövaara, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:
article id 5367, category Article
Kari Heliövaara, Rauno Väisänen. (1989). Quantitative variation in the elemental composition of Scots pine needles along a pollutant gradient. Silva Fennica vol. 23 no. 1 article id 5367. https://doi.org/10.14214/sf.a15526

Quantitative variation in the elemental composition of living Scots pine needles was studied along an atmospheric pollutant gradient in the surroundings of the industrial town Harjavalta, south-western Finland. Two 9-km-long transects, each with nine sample plots, running to the S and SW from factory complex were delimited in a homogenous Scots pine (Pinus sylvestris L.) forest. Needle samples were taken from 10 trees at each site, and from two separate sites in Tuusula near Helsinki. There was considerable spatial variation in the elemental composition of the needles. Heavy metals (Cu, Fe, Zn) showed a clear pattern of exponentially decreasing concentration with increasing distance from the emission source. Sodium and potassium concentrations, as well as the ash weight and air-dry weight, also decreased. Magnesium, manganese and calcium concentrations increased with increasing distance.

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  • Heliövaara, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:
article id 5364, category Article
Urban Bergsten. (1988). Invigoration and IDS-sedimentation of Pinus sylvestris seeds from northern Finland. Silva Fennica vol. 22 no. 4 article id 5364. https://doi.org/10.14214/sf.a15521

In Northern Finland as well as in Northern Sweden there is a shortage of high-quality Scots pine (Pinus sylvestris L.) seeds, mostly due to unsuitable temperatures during the development and maturation of cones and seeds. Methods have been developed for elimination of non-productive seeds and for invigoration of seeds. In the present work, these methods were tested on poorly developed seed lot from Rovaniemi, Northern Finland (66°15’–66°30’; 180 m a.s.l.). The seeds were conditioned using the following treatments:

1. PREVAC method (5 min, 97 kPa below atmospheric pressures) for removal of mechanically damaged seeds (7%)

2. Invigoration using incubation at controlled moisture content (30% f.w) and continuous air supply, for 14 days at 5°C.

3. Additional water supply for 16 hours at 5°C.

4. Drying in dehumidified air until a near maximum difference in density between viable and dead seeds was obtained

5. Separation in a sedimentation flume to achieve a gradient of fractions of different germination rate and capacity.

The treatments resulted in an improvement of germination percentage from 33 to about 95% and a reduction in mean germination time from 8.8 days to 6 days if the control and the best fractions (32% seeds) were compared.

  • Bergsten, ORCID ID:E-mail:
article id 5361, category Article
Kari Heliövaara, Rauno Väisänen. (1988). Interactions among herbivores in three polluted pine stands. Silva Fennica vol. 22 no. 4 article id 5361. https://doi.org/10.14214/sf.a15518

Succession of insect attacks on young Scots pine (Pinus sylvestris L.) was studied in heavily, moderately and slightly polluted pine stands within a three-kilometre distance from a prominent emission source in Western Finland. The total number of pest species was highest in the moderately polluted stand, but unlike other herbivores, aphids were also abundant in the heavily polluted stands. A few positive but no negative interactions were detected between herbivores, which suggests that insect species may benefit from a previous occurrence of other species in the same tree.

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  • Heliövaara, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:
article id 5357, category Article
Heikki Hänninen, Paavo Pelkonen. (1988). Effects of temperature on dormancy release in Norway spruce and Scots pine seedlings. Silva Fennica vol. 22 no. 3 article id 5357. https://doi.org/10.14214/sf.a15514

Models concerning the effects of temperature on dormancy release in woody plants were tested using two-year old seedlings of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.). Chilling experiments suggest that the rest period has a distinct end point. Before the attainment of this end point high temperatures do not promote bud development towards dormancy release, and after it further chilling does not affect the subsequent bud development. A new hypothesis of dormancy release is suggested on the basis of a comparison between present and earlier findings. No difference in the proportion of growth commencing seedlings were detected between the forcing temperatures of 17°C and 22°C. The rest break of 50% of Norway spruce and Scots pine seedlings required six and eight weeks of chilling, respectively. Great variation in the chilling requirement was found, especially for Scots pine.

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  • Hänninen, ORCID ID:E-mail:
  • Pelkonen, ORCID ID:E-mail:
article id 5356, category Article
Pekka Lähdesmäki, Pekka Pietiläinen. (1988). Seasonal variation in the nitrogen metabolism of young Scots pine. Silva Fennica vol. 22 no. 3 article id 5356. https://doi.org/10.14214/sf.a15513

Seasonal changed in total nitrogen, protein, amino acid, ammonia, nitrate and nitrite concentrations, and nitrate reductase and γ-glutamyltransferase activities in the needles, buds and shoots of young Scots pine (Pinus sylvestris L.) were studied. A relationship between the variation in the nitrogen metabolism and both winter dormancy and its breaking was proposed. Pine tissues stored soluble nitrogen over the winter largely in the form of arginine which, in addition to a high nitrogen content, can neutralize acidic cytoplasmic constituents such as nitrates and nitrites. Specific nitrate reductase and γ-glutamyltransferase activities were highest in late summer or autumn, and is apparently connected to the mobilization of nitrogen reserves for the winter.

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  • Lähdesmäki, ORCID ID:E-mail:
  • Pietiläinen, ORCID ID:E-mail:
article id 5354, category Article
Jan-Erik Nilsson. (1988). Variation in the rate of winter hardening of one-year-old plus-tree families of Scots pine raised in different enviroments. Silva Fennica vol. 22 no. 3 article id 5354. https://doi.org/10.14214/sf.a15511

The effect of different environmental conditions (four outdoor localities and one greenhouse locality in Northern Sweden) on cold hardening of 29 one-year-old full-sib families from plus-trees of Scots pine (Pinus sylvestris L.) were studied by artificial freeze testing. Plants exposed to low night temperatures during August achieved faster cold hardening than plants raised in milder localities. The family ranking for rate of winter hardening was consistent among outdoor localities if freeze testing was performed at times when plants from different localities had attained similar levels of cold hardiness. However, significant family x locality interactions were obtained when plants from the outdoor localities were freeze tested on the same occasion. Freeze damage was positively correlated with plant height but not correlated with dry matter content in the autumn. Freezing damage of greenhouse raised plus-tree families was uncorrelated with damage of plants raised outdoors. Possible implications for hardiness breeding are suggested.

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  • Nilsson, ORCID ID:E-mail:
article id 5352, category Article
Lars Christersson, Heinrich A. von Fircks. (1988). Injuries to conifer seedlings caused by simulated summer frost and winter desiccation. Silva Fennica vol. 22 no. 3 article id 5352. https://doi.org/10.14214/sf.a15509

Visible frost damage to forest trees in Sweden seldom occurs in winter but is frequent in late spring, summer and early autumn. Frosts are frequent in all seasons in various parts of Sweden, even in the southernmost part (lat. 56°, N) and temperatures may be as low as -10°C even around mid-summer. Ice crystal formation within the tissues, which in most seedlings takes place at around -2°C, causes injury, not the sub-zero temperatures themselves.

The apical meristem, the elongated zone, and the needles of seedlings of Picea abies (L.) H. Karst. in a growing phase were damaged at about -3°C and those of Pinus sylvestris L. at about -6°C. Other species of the genus Pinus were tested and most were found to be damaged at about -6°C, with some variations. Picea species tested were damaged at about -3°C to -4°C.

A method has been designed to compare the response of different species to winter desiccation, which occurs under conditions of (1) low night temperature, (2) very high irradiation and increase in needle temperature during the photoperiod, (3) frozen soil, and (4) low wind speed. There were differences in response to winter desiccation between pine and spruce species. Seedlings of Pinus contorta tolerated these winter desiccation conditions much better than those of P. sylvestris or Picea abies. Picea mariana was the least tolerant of the species tested.

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  • Christersson, ORCID ID:E-mail:
  • Fircks, ORCID ID:E-mail:
article id 5347, category Article
Timo Kuuluvainen, Markku Kanninen, Juha-Pekka Salmi. (1988). Tree architecture in young Scots pine: properties, spatial distribution and relationships of components of tree architecture. Silva Fennica vol. 22 no. 2 article id 5347. https://doi.org/10.14214/sf.a15504

The architecture of Scots pine (Pinus sylvestris L.) was studied in an eight-year-old progeny test. The measurements included characteristics of crown structure, spatial distribution of shoots and yield components. The spatial distribution of shoots showed striking between-tree differences, and two extreme distribution patterns were detected. One represented a non-layered structure with a vertically relative even shoot distribution, and the other a layered structure with a vertically highly uneven shoot distribution.

Close correlations existed between several components of tree architecture and it is suggested that changes in the phenotypic architecture in Scots pine follow an epigenetic pattern, which enables the prediction of adaptational changes in structural components. The structural characteristics related to high above-ground biomass were a long crown, high total shoot length, high number of branches per whorl and big shoots of low needle density occupying a big share of the crown volume.

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  • Kuuluvainen, ORCID ID:E-mail:
  • Kanninen, ORCID ID:E-mail:
  • Salmi, ORCID ID:E-mail:
article id 5338, category Article
Timo Pukkala. (1988). Effect of spatial distribution of trees on the volume increment of a young Scots pine stand. Silva Fennica vol. 22 no. 1 article id 5338. https://doi.org/10.14214/sf.a15495

The effect of grouping on 5-year old volume increment was studied by a simulation technique using spatial growth models estimated in Scots pine (Pinus sylvestris L.) stands in the phase of the first commercial thinning. A total of 24 model stands were regenerated by applying 12 spatial processes for two different diameter distributions. In addition to model stands, 6 different thinnings were simulated in two real stands. The clustering of trees was described with Fisher’s grouping index and by estimating the relative interception of diffuse radiation. In model stands with constant diameter distribution the correlation between the grouping index and volume increment ranged from -0.81 to -0.91. The correlation between volume increment and interception was 0.81–0.83 with one diameter distribution and 0.70 if both distributions were combined. In one thinned stand the correlation between the growth estimate and grouping index varied between -0.33 and 0.76. The correlation between interception and growth was about 0.30 in one stand and 0.72 if both stands were combined. Small irregularities do not decrease the volume production of a young Scots pine stand, but if the clustering is considerable or there are reasonably wide harvest strips, growth will be reduced by 10–20%.

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  • Pukkala, ORCID ID:E-mail:
article id 5318, category Article
Tapio Lindholm, Harri Vasander. (1987). Vegetation and stand development of mesic forest after prescribed burning. Silva Fennica vol. 21 no. 3 article id 5318. https://doi.org/10.14214/sf.a15475

This study deals with the succession of vegetation and tree stand in 16 mesic Myrtillus site type Scots pine (Pinus sylvestris L.) plantations after prescribed burning in Evo, Southern Finland. The oldest tree stands studied were about 30-year-old. The growth of trees followed the height index of Myrtillus type. The vegetation was first mesic, dominated by grasses and herbs, turning more xeric after four years. This change was accelerated by treatment with herbicides. After the closure of tree stand, vegetation became more characteristic of forest vegetation, but pioneer species and composition disappeared slowly. The basic characters of vegetation succession could be clearly described by DCA ordination and TWINSPAN classification. The study confirmed that Myrtillus type has succession phases which are typical for each age phases as Cajander’s forest site type theory has proposed. However, differences in primary and secondary site factors have their own effects on the vegetation of the succession phases.

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  • Lindholm, ORCID ID:E-mail:
  • Vasander, ORCID ID:E-mail:
article id 5315, category Article
Seppo Kellomäki, Matti Seppälä. (1987). Simulations on the effects of timber harvesting and forest management on the nutrient cycle and productivity of Scots pine stands. Silva Fennica vol. 21 no. 2 article id 5315. https://doi.org/10.14214/sf.a15472

Effects of varying rotation, thinning, fertilization and harvest intensity on the productivity and nitrogen cycle of Scots pine (Pinus sylvestris L.) stand were studied on the basis of computer simulation. The increasing intensity of management increased the loss of nitrogen in the cycle. Short rotation, associated with early thinning by means of the whole tree harvest, proved to be especially detrimental regarding the productivity of the forest ecosystem. Fertilization associated with thinnings is of great importance in maintaining the productivity of a forest ecosystem during an intensive timber harvest.

The PDF includes an abstract in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Seppälä, ORCID ID:E-mail:
article id 5312, category Article
Timo Pukkala. (1987). Siementuotannon vaikutus kuusen ja männyn vuotuiseen kasvuun. Silva Fennica vol. 21 no. 2 article id 5312. https://doi.org/10.14214/sf.a15469
English title: Effect of seed production on the annual growth of Picea abies and Pinus sylvestris.

The study material consisted of 13 rather old Norway spruce (Picea abies (L.) H. Karst.) and 17 Scots pine (Pinus sylvestris L.) stands located in different parts of Finland. In each stand the seed crops, radial growth and amount of latewood were measured during a period of about ten years. Seed production reduces the radial growth of spruce and pine in the year of seed maturing. In Southern and Central Finland also the proportion of latewood is reduced. Seed production accounts for about 14% of the variation in radial growth of a spruce stand growing in Lapland, and 27% in other parts of Finland. In pine stands the seed crop explains 19% of the variation in radial growth in Lapland, and only 7% in the rest of Finland. In spruce stands an average seed crop reduces radial growth by 14% in Lapland and 5% in the rest of the country. An abundant seed production causes a reduction of about 20%. In southern parts of Finland, the proportion of latewood is reduced by 5% in an average seed year and by 24% in a good seed year. In pine stands an average seed crop decreases the width of annual ring by 5%, and a good seed crop by 15%. Outside Lapland, also the proportion of latewood is reduced: in an average seed year by 5%, and in a good seed year by 16%. The reduction in volume growth of spruce stands due to an average seed crop was estimated to be about 10% in Lapland, and 6% in other parts of Finland. A prolific seed production causes a reduction of 20%. In old pine stands the reduction is 5% in an average seed year, and 15% in a good seed year.

The PDF includes an abstract in English.

  • Pukkala, ORCID ID:E-mail:
article id 5311, category Article
Timo Pukkala. (1987). Kuusen ja männyn siemensadon ennustemalli. Silva Fennica vol. 21 no. 2 article id 5311. https://doi.org/10.14214/sf.a15468
English title: Model for predicting the seed crop of Picea abies and Pinus sylvestris.

The seed crop of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) is predicted with the help of mean monthly temperatures during May–August one and two years before the flowering year. The prediction models were made separately for Lapland and for the rest of Finland. The models are based on 10-year periods of seed crop measurements and climatic data. The total number of time series was 59.

In Lapland, Norway spruce flowered abundantly and produced an abundant seed crop after warm July–August and two years after cool July–August. In other parts of Finland, warm June and July produced a good flowering year, especially if these months were cool two years before the flowering year.

In Lapland, Scots pine flowered abundantly if the whole previous growing season was warm. Elsewhere in Finland, a cool June preceded prolific flowering in the coming year if the rest of the growing season was considerably warmer than the average.

The prediction models explained 37–49 % of the variation in the size of the seed crop. The occurrence of good and poor seed years was usually predicted correctly. Using the presented models, the prediction of the seed crop is obtainable 1.5 year for Norway spruce and 2.5 year for Scots pine before the year of seed fall.

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  • Pukkala, ORCID ID:E-mail:
article id 5310, category Article
Petri Kärenlampi. (1987). Puun lahonkestävyys ja kosteusdynamiikka. Silva Fennica vol. 21 no. 2 article id 5310. https://doi.org/10.14214/sf.a15467
English title: The decay resistance and moisture dynamics of wood.

In laboratory studies the heartwood content seems to be the only natural property of a wood of different tree species influencing the decay resistance. Moistening and drying by diffusion happen quite slowly. Scots pine (Pinus sylvestris L.) sapwood takes moisture by capillary action quicker than pine heartwood and Norway spruce (Picea abies (L.) H. Karst.) wood. Swelling and shrinkage are also greatest in pine sapwood. Impregnation of pine sapwood can give it better hydrophobic and dimensional stability than that of pine heartwood.

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  • Kärenlampi, ORCID ID:E-mail:
article id 5306, category Article
Timo Pukkala, Taneli Kolström. (1987). Competition indices and the prediction of radial growth in Scots pine. Silva Fennica vol. 21 no. 1 article id 5306. https://doi.org/10.14214/sf.a15463

The effect of competition on the radial growth of Scots pine (Pinus sylvestris L.) was studied in three naturally regenerated stands located in North Karelia, Finland. The competition situation of an individual tree was described with various competition indices which depended on the sizes and distances from the neighbouring trees. One competition index explained about 50% of the variation in 5-year radial growth in one stand. If all stands were combined, one index explained 43.5%, two indices 48.9% and three indices 51.2% of the variation. In one stand, the best competition indices accounted for about 20% of that variation which could not be explained by tree diameter. If all three stands were combined, the best index explained 11% of the residual variation. About 40% of the variation in 5-year radial growth could not be explained by the diameter and competition indices.
The PDF includes an abstract in Finnish.

  • Pukkala, ORCID ID:E-mail:
  • Kolström, ORCID ID:E-mail:
article id 5305, category Article
Timo Pukkala. (1987). Simulation model for natural regeneration of Pinus sylvestris, Picea abies, Betula pendula and Betula pubescens. Silva Fennica vol. 21 no. 1 article id 5305. https://doi.org/10.14214/sf.a15462

In the model the regeneration process is derived into three subprocesses: birth, growth and mortality of seedlings. The main emphasis is on the birth process where the following phases are simulated: seed crop, quality of seeds, maturity of seeds, predation of seeds and germination. The parameters are based on data published in Finland. Part of the parameters are obtained directly from the investigations and part is proposed by the author. The model can be calibrated by changing parameter values. The simulation is made with the help of random numbers which have the same means as the estimates and the same distributions as the residuals of the equations used in simulation. The time step of the model is one year. The number of emerged seedlings in one year is obtained by multiplying the seed crop with the probabilities that the seed passes different phases of the birth process. Because of stochasticity the regeneration period is simulated several times. From the results it is possible to evaluate the risk and succeeding probability of the regeneration. The main drawbacks of the simulation method are the lack of empirical parameters and the difficulty of testing. The model could be further developed by including spatiality into the model.

The PDF includes an abstract in Finnish.

  • Pukkala, ORCID ID:E-mail:
article id 5303, category Article
Hannu Raitio. (1987). Neulasvuosikertojen merkitys neulasanalyysin tulkinnassa. Silva Fennica vol. 21 no. 1 article id 5303. https://doi.org/10.14214/sf.a15460
English title: The significance of the number of needle year classes of Scots pine in interpreting needle analysis results.

This study deals with significance of the number of needle year classes in estimating the nitrogen, phosphorus, potassium and magnesium status of Scots pine (Pinus sylvestris L.) plants on the basis of needle analysis. Due to the nutrient retranslocation deficiencies in these nutrients are best determined by analysing separately the needles of the topmost branch whorls possessing one, two or three needle year classes. The concentrations of those nutrients which are not scarce will then increase as needle year classes decrease. In cases of deficiency, on the other hand, the content of the nutrient concerned will remain the same or decrease. Only severe deficiencies are revealed by the examination of the nutrient concentrations of only the youngest or the oldest needles.

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  • Raitio, ORCID ID:E-mail:
article id 5302, category Article
Seppo Kellomäki, Heikki Hänninen, Taneli Kolström, Ahti Kotisaari, Timo Pukkala. (1987). A tentative model for describing the effects of some regenerative process on the properties of natural seedling stands. Silva Fennica vol. 21 no. 1 article id 5302. https://doi.org/10.14214/sf.a15459

The effect of the size of seed crop, dispersal of seeds and the early development of seedlings on the density and spatial distribution of young Scots pine (Pinus sylvestris L.) stands are evaluated on the basis of theoretical models. The models include (i) number and spatial distribution of parent trees on the regeneration area, (ii) size of annual seed crop, (iii) seed dispersal from a particular parent tree, (iv) germination of the seeds (germination percentage), (v) death of ageing seedlings after the establishment process, and (vi) height growth of the seedlings.

As expected, stand density and spatial distribution varied within a large range in relation to the density of the parent trees and the distance from them. The simulations also showed that natural seedling stands can be expected to be heterogenous due to the geometry of seed dispersal, emphasizing the frequency of young and small trees. The properties of the seedling stands were, however, greatly dependent on the density of the parent trees and the length of the regeneration period.

The PDF includes an abstract in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Hänninen, ORCID ID:E-mail:
  • Kolström, ORCID ID:E-mail:
  • Kotisaari, ORCID ID:E-mail:
  • Pukkala, ORCID ID:E-mail:
article id 5276, category Article
Kari Heliövaara, Rauno Väisänen. (1986). Parasitization in Petrova resinella (Lepidoptera, Tortricidae) galls in relation to industrial air pollutants. Silva Fennica vol. 20 no. 3 article id 5276. https://doi.org/10.14214/sf.a15455

Paratization of Petrova resinella L. in the gall stage was studied in the surrounding of Harjavalta, south-western Finland, in relation to industrial air pollution. Of the studied 283 galls, 28% produced a moth, 52% of the larvae/pupae were paratisized, and 20% were empty or contained a dead larva. The proportion of paratisized galls did not depend on the distance from emission sources of industrial air pollutants.

The PDF includes an abstract in Finnish.

  • Heliövaara, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:
article id 5275, category Article
Pirkko Velling, Gérard Nepveu. (1986). Männyn puuaineen laadun ja tuotoksen vaihtelu suomalaisessa provenienssikoesarjassa. Silva Fennica vol. 20 no. 3 article id 5275. https://doi.org/10.14214/sf.a15454
English title: Variation of wood quality and yield in a Finnish series of provenance trials on Scots pine.

The purpose of the study was to determine the effects of the origin of seeds and the location of cultivation of Scots pine (Pinus sylvestris L.) on certain properties particularly important to the pulp industry. The research material consisted of six parallel trials of the same 12 provenances. Increment cores were taken of a total of 1,267 sample trees, 19 years old. The location of the trial site generally affected the properties to a larger extent than the origin of the seed. The effect of the variation of wood density and fibre yield on the cultivation values of the provenances was only a few percentages on average, however, at most the effect was nearly 10%. Eastern Finnish provenances adapted well to western Finnish conditions.

The PDF includes an abstract in Finnish and French.

  • Velling, ORCID ID:E-mail:
  • Nepveu, ORCID ID:E-mail:
article id 5274, category Article
Pertti Hari, Pirkko Heikinheimo, Leo Kaipiainen, Eeva Korpilahti, Annikki Mäkelä, Juha Samela. (1986). Trees as a water transport system. Silva Fennica vol. 20 no. 3 article id 5274. https://doi.org/10.14214/sf.a15453

The structure of 20 Scots pine (Pinus sylvestris L.) trees was analysed as a water transport system. There is a tight linear regression between the cross-sectional area of the stem at the height of its lowest living branch and the cross-sectional area of its coarse roots, between the cross-sectional area of the stem at the height of its lowest living branch and the total cross-sectional area of its branches, and between the cross-sectional area of the base of a branch and the total cross-sectional area of subsidiary branches of that branch. The capacity of successive organs, measured as cross-sectional areas, to transport water was thus found to be regular within a tree.

The PDF includes an abstract in Finnish.

  • Hari, ORCID ID:E-mail:
  • Heikinheimo, ORCID ID:E-mail:
  • Kaipiainen, ORCID ID:E-mail:
  • Korpilahti, ORCID ID:E-mail: eeva.korpilahti@luke.fi
  • Mäkelä, ORCID ID:E-mail:
  • Samela, ORCID ID:E-mail:
article id 5270, category Article
Pekka Kilkki, Risto Päivinen. (1986). Weibull function in the estimation of the basal area dbh-distribution. Silva Fennica vol. 20 no. 2 article id 5270. https://doi.org/10.14214/sf.a15449

The paper demonstrates the possibility of using data from small relascope sample plots in the derivation of the regression models which predict the Weibull function parameters for the dbh-distribution. The Weibull parameters describing the basal area dbh-distribution were estimated for relascope sample plots from the Finnish National Forest Inventory. In the first stage of the estimation nonlinear regression analysis was employed to derive initial parameter estimates for the second stage, in which the maximum likelihood method was used. The parameter estimates were employed as dependent variables for the derivation of the regression models; the independent variables comprised of the compartment-wise stand variables generally estimated in ocular inventories.

The PDF includes an abstract in Finnish.

  • Kilkki, ORCID ID:E-mail:
  • Päivinen, ORCID ID:E-mail:
article id 5267, category Article
Matti Kärkkäinen. (1986). Mänty- ja kuusirunkojen arvosuhteet. Silva Fennica vol. 20 no. 2 article id 5267. https://doi.org/10.14214/sf.a15446
English title: Value relations of Scots pine and Norway spruce stems.

A mathematical model was developed for determining the value of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) stems on the basis of sawing and pulping. The model was based on selling prices of sawn goods, pulp and other products as well as processing costs. Sawing was applied to large-dimension parts of stems and pulping to other parts and small stems. Bark and other residues were burned. The quality of pine stems was described by the distance of the lowest dead branch. In spruce only stem size affected the quality-

According to the results, the size of stem affects considerably the value of pine stems and clearly that of spruce stems. The main reason is an increase in the productivity of frame sawing as the stem size increases. In pine another factor is the higher price of sawn goods. The effect of pulp price increases as the stem size decreases. Even in large sized stems the effect of pulp was notable as the value of chips and saw dust was determined on the basis of product values in export. The competition ability of mechanical pulp was greatly affected by the price of electricity.

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  • Kärkkäinen, ORCID ID:E-mail:
article id 5266, category Article
Matti Kärkkäinen. (1986). Malli männyn, kuusen ja koivun puuaineen oksaisuudesta. Silva Fennica vol. 20 no. 2 article id 5266. https://doi.org/10.14214/sf.a15445
English title: Model of knottiness of wood material in pine, spruce and birch.

A computer model was developed for predicting knottiness of wood material of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and birch (Betula sp). The prediction included location of knots, their size and quality, i.e. if they are dead or living knots. The model suits best for tree species where branches are born at the base of shoots, in Finland such tree species is Scots pine.

The usefulness of the model was tested in the prediction of knots in wooden elements of joinery industry. According to the results, the shape of cross section affects the surface quality of elements. Especially useful is a quadratic cross section as it increases the probability to get a knotless surface.

The PDF includes an abstract in English.

  • Kärkkäinen, ORCID ID:E-mail:
article id 5265, category Article
J. Ross, S. Kellomäki, P. Oker-Blom, V. Ross, L. Vilikainen. (1986). Architecture of Scots pine crown. Silva Fennica vol. 20 no. 2 article id 5265. https://doi.org/10.14214/sf.a15444

Dimensions (length, width and thickness) of needles in crowns of young Scots pine (Pinus sylvestris L.) were found to be related linearly to each other. Similarly, the needle area was linearly correlated with the needle biomass. In the lower crown, needle length was linearly correlated with the length of the shoot, but in the upper crown needle length did not vary according to any regular pattern. Needle density was negatively correlated with shoot length. In the lower crown the needle density varied 20–40 cm-1 and in the upper crown 15– 20 cm-1. The increasing angle of aging needles seemed to be characteristic for Scots pine shoots.

The PDF includes an abstract in Finnish.

  • Ross, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Oker-Blom, ORCID ID:E-mail:
  • Ross, ORCID ID:E-mail:
  • Vilikainen, ORCID ID:E-mail:
article id 5264, category Article
Kari Heliövaara. (1986). Occurrence of Petrova resinella (Lepidoptera, Tortricidae) in a gradient of industrial air pollutants. Silva Fennica vol. 20 no. 2 article id 5264. https://doi.org/10.14214/sf.a15443

The relationship between industrial air pollutants and the occurrence of galls of Petrova resinella (Lepidoptera, Torticiadae) was studied around the industrialized town of Harjavalta in Western Finland. There were 44 sampling sites set out at logarithmic distances along five transects (NW, W, SW, SE) froma a distive source of emissions. Each site consisted of three circular sample plots (30 m2) in young Scots pine (Pinus sylvestris L.) stands. The number of galls, including cankers from several years earlier, was highest in the vicinity of the factory complex on each transect. The highest number of two-year-old galls containing living larvae was usually recorded at the ends of the transects several kilometres from the factories. However, the significance of the differences both between zones and transects was rather low. Correlations between the deposition of heavy metals (Cd, Cu, Ni, Pb, Zn), used as an indication of the general level of air pollution, and the total number of galls, were positive and generally highly significant. It is concluded that P. resinella has benefitted from air pollution although perhaps to less extent than some sap-sucking species.

The PDF includes an abstract in Finnish.

  • Heliövaara, ORCID ID:E-mail:
article id 5262, category Article
Markku Nygren. (1986). Männyn siementen syyskeräys. Silva Fennica vol. 20 no. 1 article id 5262. https://doi.org/10.14214/sf.a15441
English title: Autumn harvested Scots pine seeds: the effect of cone storage and germination conditions on germination capacity.

Six seed collections were made in September–December 1984 in a natural Scots pine (Pinus sylvestris L.) stand in Southern Finland. The seeds were germinated immediately after the cone collection and three photoperiods (0.8 and 24 hours) were used in germination tests.

The seeds collected in September and October possessed relative dormancy, i.e. they did not germinate in darkness and at 10°C. Later in November and December the seeds were capable to germinate in darkness and at low temperature also. The gradual change in germination capacity is attributed to chilling temperatures in natural environments or in cone storage.

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  • Nygren, ORCID ID:E-mail:
article id 5259, category Article
Kari Löyttyniemi, Olli Uusvaara. (1986). Further tests for termite resistance of Finnish pine heartwood. Silva Fennica vol. 20 no. 1 article id 5259. https://doi.org/10.14214/sf.a15438

The natural resistance of Finnish-grown Pinus sylvestris L. heartwood to Macrotermitinae termites was tested in Zambia in graveyard conditions. The heartwood exhibited some natural resistance but durability was, however, far from practical immunity. There was significant tree-to-tree variation in the resistance of heartwood of P. Sylvestris.

The PDF includes a summary in Finnish.

  • Löyttyniemi, ORCID ID:E-mail:
  • Uusvaara, ORCID ID:E-mail:
article id 5255, category Article
Matti Kärkkäinen, Jukka Pietilä, Raili Vihola. (1985). Suomalaisten puulajien iskutaivutuslujuus tuoreena. Silva Fennica vol. 19 no. 4 article id 5255. https://doi.org/10.14214/sf.a15434
English title: Impact bending strength of Finnish tree species in green condition.

There are great impact forces in mechanized harvesting and wood yard in the mills which can cause breaks in timber. The impact strength of timber in green condition was tested in temperatures of +18°C and -18°C using sawn pieces (20 x 20 x 300 mm) of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), birch (Betula pendula Roth and B. pubescens Ehrh.), grey alder (Alnus incana L.) and aspen (Populus tremula L.). In addition, unbarked naturally round sticks (length 300 mm, diameter 15 and 35 mm) of the same species were tested.

The impact strength of round sticks was 1.5–4.4 times as great as that of sawn pieces. The reasons are possibly the avoidance of cell breaks at the surface as well as growth stresses. The frozen samples were clearly weaker than the unfrozen ones. As a rule, the impact bending strength increased with increased density of the species. However, the correlation varied greatly between species. If density was kept constant, an increase in the growth ring width decreased the impact strength. The reason may lie in the fracture mechanism.

The PDF includes a summary in English.

  • Kärkkäinen, ORCID ID:E-mail:
  • Pietilä, ORCID ID:E-mail:
  • Vihola, ORCID ID:E-mail:
article id 5252, category Article
Kari Löyttyniemi. (1985). On repeated browsing of Scots pine saplings by moose (Alces alces). Silva Fennica vol. 19 no. 4 article id 5252. https://doi.org/10.14214/sf.a15431

The size, nutrient contents and terpene composition of needles of Scots pine (Pinus sylvestris L.) saplings untouched and repeatedly browsed by the moose (Alces alces L.) were compared. Material was collected from a 14-years old and 2.5 m high pine stand in Bromarv, Southern Finland. The average length and fresh and dry weight of the needles were measured, and nutrient content (N, P, K, Ca, Mg, B, Cu) was determined.

The needles of repeatedly browsed pines became long and robust. There was, however, no difference between the dry matter percentage between the needles. The average nitrogen content was higher in the rebrowsed trees. Nitrogen content is, however, not directly correlated with the palatability of pine needles. Even phosphorus and boron content were higher in the damaged trees. No difference was found in Ca, K, Mg and Cu contents of the browsed and control pine saplings.

The PDF includes a summary in Finnish.

  • Löyttyniemi, ORCID ID:E-mail:
article id 5251, category Article
Markku Halinen. (1985). Männyn nuoruusvaiheen kasvunopeuden vaikutus sahatavaran laatuun. Silva Fennica vol. 19 no. 4 article id 5251. https://doi.org/10.14214/sf.a15430
English title: The effect of the growth rate of young Scots pine on the quality of sawn goods.

Totally 653 battens and planks sawn from butt logsof Scots pine (Pinus sylvestris L.) were chosen from 3 saw mills. The sawn goods were sorted according to normal sorting principles. In order to determine growth rate in the youth, the mean value of the average ring width was measured at the butt end at various distances from the pith.

The average ring width increased as the quality of the sawn goods decreased. The difference between the quality classes in ring width was measured between 2 and 4 cm from the pith. As the size of sawn goods, and, simultaneously, the log size increased, the average ring width increased in a given quality class. Research reinforced previous results, in which slow diameter growth of young Scots pines has been shown to reflect the good quality of sawn goods.

The PDF includes a summary in English.

  • Halinen, ORCID ID:E-mail:
article id 5246, category Article
Matti Kärkkäinen, Markku Halinen. (1985). Mäntysahatukkien minimivaatimusten täsmentäminen. Silva Fennica vol. 19 no. 3 article id 5246. https://doi.org/10.14214/sf.a15425
English title: Reappraisal of minimum requirements of Scots pine saw logs.

A test sawing was made of 807 Scots pine (Pinus sylvestris L.) saw logs of varying size and quality. The most important knot characteristic affecting the value of sawn goods was the diameter of the thickest dry knot. The new minimum requirements for pine logs were proposed on the basis of top diameter of the log and the diameter of the thickest dry and living knot.

The PDF includes a summary in English

  • Kärkkäinen, ORCID ID:E-mail:
  • Halinen, ORCID ID:E-mail:
article id 5243, category Article
Eljas Pohtila, Tapani Pohjola. (1985). Maan kunnostus männyn viljelyssä Lapissa. Silva Fennica vol. 19 no. 3 article id 5243. https://doi.org/10.14214/sf.a15422
English title: Soil preparation in reforestation of Scots pine in Lapland.

The study deals with the interaction of various soil preparation and reforestation methods. The most favourable time of the year for broadcast sowing and the effect of stabilization after soil preparation on restocking were studied as special problems.

Prescribed burning, scalping and disc ploughing made a better combination with sowing than planting, and ploughing better combination with planting than sowing. The longer the period was between sowing and germination the fewer seedlings emerged. The best stocking was clearly resulted with sowing in June. Stabilization of soil after preparation had a negative effect on reforestation results.

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  • Pohtila, ORCID ID:E-mail:
  • Pohjola, ORCID ID:E-mail:
article id 5239, category Article
Jussi Kuusipalo. (1985). On the use of tree stand parameters in estimating light conditions below the canopy. Silva Fennica vol. 19 no. 2 article id 5239. https://doi.org/10.14214/sf.a15418

Especially in forest vegetation studies, the light climate below the canopy is of great interest. In extensive forest inventories, direct measurement of the light conditions is too time-consuming. Often only the standard tree stand parameters are available. The present study was undertaken with the aim to develop methods for estimation of the light climate on the basis of readily measurable tree stand characteristics. The study material includes 40 sample plots representing different kinds of more or less mature forest stands of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.).

In each forest stand, a set of hemipherical photographs was taken and standard tree stand measurements were performed. A regression approach was applied in order to elaborate linear models for predicting the canopy coverage. The total basal area of the stand explained 63% of variance in the canopy coverage computed from hemipherical photographs. A coefficient representing the relative proportion of Norway spruce in the stand increased the explanatory power into 75%. When either the stand density (stems/unit area) or dominant age of the stand was included into the model, incr