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Articles containing the keyword 'temperature'.

Category: Research article

article id 7751, category Research article
Göran Nordlander, Euan G. Mason, Karin Hjelm, Henrik Nordenhem, Claes Hellqvist. (2017). Influence of climate and forest management on damage risk by the pine weevil Hylobius abietis in northern Sweden. Silva Fennica vol. 51 no. 5 article id 7751. https://doi.org/10.14214/sf.7751
Highlights: Analysis of survey data from 292 reforestation areas in northern Sweden show that the probability of pine weevil damage can be predicted with a standard error of 0.12; Three variables are important in the optimal model: proportion of seedlings in mineral soil, age of clear-cut, and temperature sum; Temperature sum in the model can be adjusted to reflect future climate scenarios.

The pine weevil Hylobius abietis L. is an economically important pest insect that kills high proportions of conifer seedlings in reforestation areas. It is present in conifer forests all over Europe but weevil abundance and risk for damage varies considerably between areas. This study aimed to obtain a useful model for predicting damage risks by analyzing survey data from 292 regular forest plantations in northern Sweden. A model of pine weevil attack was constructed using various site characteristics, including both climatic factors and factors related to forest management activities. The optimal model was rather imprecise but showed that the risk of pine weevil attack can be predicted approximatively with three principal variables: 1) the proportion of seedlings expected to be planted in mineral soil rather than soil covered with duff and debris, 2) age of clear-cut at the time of planting, and 3) calculated temperature sum at the location. The model was constructed using long-run average temperature sums for epoch 2010, and so effects of climate change can be inferred from the model by adjustment to future epochs. Increased damage risks with a warmer climate are strongly indicated by the model. Effects of a warmer climate on the geographical distribution and abundance of the pine weevil are also discussed. The new tool to better estimate the risk of damage should provide a basis for foresters in their choice of countermeasures against pine weevil damage in northern Europe.

  • Nordlander, Swedish University of Agricultural Sciences (SLU), Department of Ecology, P.O. Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: Goran.Nordlander@slu.se
  • Mason, University of Canterbury, School of Forestry, Private Bag 4800, Christchurch 8140, New Zealand; Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID: http://orcid.org/0000-0001-9024-9106 E-mail: euan.mason@canterbury.ac.nz (email)
  • Hjelm, Skogforsk, The Forest Research Institute of Sweden, Ekebo 2250, SE-268 90 Svalöv, Sweden; Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: karin.hjelm@skogforsk.se
  • Nordenhem, Swedish University of Agricultural Sciences (SLU), Department of Ecology, P.O. Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: h.nordenhem@telia.com
  • Hellqvist, Swedish University of Agricultural Sciences (SLU), Department of Ecology, P.O. Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: Claes.Hellqvist@slu.se
article id 1520, category Research article
Tomáš Kolář, Kyriaki Giagli, Miroslav Trnka, Emílie Bednářová, Hanuš Vavrčík, Michal Rybníček. (2016). Response of the leaf phenology and tree-ring width of European beech to climate variability. Silva Fennica vol. 50 no. 2 article id 1520. https://doi.org/10.14214/sf.1520
Highlights: The timing of leaf phenological phases in European beech is controlled by temperature; Tree-ring width variations in European beech positively reflect growing season precipitation and soil water availability; The water availability in the top 40 cm of soil layer is more important for European beech growth than that in the deeper layers; Extension of the phenological growing season does not increase tree-ring width.

Various environmental conditions (heat waves and drought events) strongly affect leaf and xylem phenology. Disentangling the influence of temperature, precipitation and soil moisture content (AWR) on the forest productivity remains an important research area. We analyzed the impact of climate variability on the leaf phenology (10 sample trees) and radial growth (17 sample trees) of European beech (Fagus sylvatica L.). The study was conducted on 130-year-old European beech trees growing in a temperate forest stand in the Czech Republic. Detailed 20-year phenological monitoring was performed at the study site (1992–2011). As expected, leaf phenological events were mainly driven by the growing season temperatures. Leaf unfolding was highly affected positively by spring temperatures and the top-layer (to 40 cm) AWR in March. The correlation of tree-ring width with the interpolated climate data was positive significant for the growing season AWR and precipitation signal. Furthermore, the water availability in the top soil layer was found to be an important predictor of tree growth and extremely low growth occurrence. The extended phenological growing season, which was caused by a temperature increase, was not followed by an increased tree-ring width. The examined relationships point out the significance of the water availability in the top soil layer in European beech stands.

  • Kolář, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic; Global Change Research Institute, The Czech Academy of Sciences, Bělidla 986/4a, 603 00 Brno, Czech Republic ORCID ID:E-mail: koldatom@gmail.com (email)
  • Giagli, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: giagli@node.mendelu.cz
  • Trnka, Global Change Research Institute, The Czech Academy of Sciences, Bělidla 986/4a, 603 00 Brno, Czech Republic; Department of Agrosystems and Bioclimatology, Faculty of Agronomy, Mendel University in Brno, Zemědělská 1, 613 00 Brno, Czech Republic ORCID ID:E-mail: mirek_trnka@yahoo.com
  • Bednářová, Institute of Forest Ecology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědelská 3, 61300 Brno, Czech Republic ORCID ID:E-mail: bednarov@mendelu.cz
  • Vavrčík, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: vavrcik@mendelu.cz
  • Rybníček, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic; Global Change Research Institute, The Czech Academy of Sciences, Bělidla 986/4a, 603 00 Brno, Czech Republic ORCID ID:E-mail: michalryb@post.cz
article id 1326, category Research article
Joanna Bachmatiuk, Jordi Garcia-Gonzalo, Jose Guilherme Borges. (2015). Analysis of the performance of different implementations of a heuristic method to optimize forest harvest scheduling. Silva Fennica vol. 49 no. 4 article id 1326. https://doi.org/10.14214/sf.1326
Highlights: The number of treatment schedules available for each stand has an impact on the optimal configuration of opt-moves (i.e. number stands where the treatment schedule is changed in an iteration); Considering a large number of treatment schedules per stand, the one-opt move implementation is preferred, yet when considering a low number of decision choices the two-opt moves option performs better.

Finding an optimal solution of forest management scheduling problems with even flow constraints while addressing spatial concerns is not an easy task. Solving these combinatorial problems exactly with mixed-integer programming (MIP) methods may be infeasible or else involve excessive computational costs. This has prompted the use of heuristics. In this paper we analyze the performance of different implementations of the Simulated Annealing (SA) heuristic algorithm for solving three typical harvest scheduling problems. Typically SA consists of searching a better solution by changing one decision choice in each iteration. In forest planning this means that one treatment schedule in a single stand is changed in each iteration (i.e. one-opt move). We present a comparison of the performance of the typical implementation of SA with the new implementation where up to three decision choices are changed simultaneously in each iteration (i.e. treatment schedules are changed in more than one stand). This may allow avoiding local optimal. In addition, the impact of SA - parameters (i.e. cooling schedule and initial temperature) are tested. We compare our heuristic results with a MIP formulation. The study case is tested in a real forest with 1000 stands and a total of 213116 decision choices. The study shows that when the combinatorial problem is very large, changing simultaneously the treatment schedule in more than one stand does not improve the performance of SA. Contrarily, if we reduce the size of the problem (i.e. reduce considerably the number of alternatives per stand) the two-opt moves approach performs better.

  • Bachmatiuk, Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Lisboa, Portugal ORCID ID:E-mail: jbachmatiuk@isa.ulisboa.pt (email)
  • Garcia-Gonzalo, Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Lisboa, Portugal ORCID ID:E-mail: jordigarcia@isa.ulisboa.pt
  • Borges, Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Lisboa, Portugal ORCID ID:E-mail: joseborges@isa.ulisboa.pt
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 1124, category Research article
Āris Jansons, Mārtiņš Zeps, Juris Rieksts-Riekstiņš, Roberts Matisons, Oskars Krišāns. (2014). Height increment of hybrid aspen Populus tremuloides x P. tremula as a function of weather conditions in central part of Latvia. Silva Fennica vol. 48 no. 5 article id 1124. https://doi.org/10.14214/sf.1124
Highlights: Intra-annual height growth of hybrid aspen was monitored; Clones with early leaf flushing dates showed faster height growth; Height growth was generally controlled by temperature; Fast-growing hybrids were more robust to weather conditions than slow-growing ones; Potential evapotranspiration (moisture regime) negatively affected height growth of clones with delayed phenology.
Height growth of young hybrid aspen (Populus tremula L. × P. tremuloides Michx.) was studied in relation to weather conditions. Height of clones with different leaf flushing phenology (early, intermediate and late) was monitored during the growing periods of 2010 and 2011 in a plantation established on former agricultural land. Mean daily height increment (HI) was calculated. Multiple linear regression was used to determine which weather factors (variables) had significant effect on HI. Mean seasonal height growth (mean seasonal HI) between clones (groups) was compared by ANOVA. In both years, HI was significantly higher for clones with early and intermediate leaf flushing compared to clones with late leaf flushing. The effect of weather factors also differed between clones according to their leaf flushing phenology; it was the weakest for HI of clones with early leaf flushing compared to clones with intermediate and late leaf flushing. Mean temperature was the main factor, which positively affected HI of all clones, suggesting that warmer climate might be beneficial for height growth of young hybrid aspen in Latvia. Nevertheless, significant negative relationship between HI and potential evapotranspiration (PET) was observed for clones with delayed leaf flushing, suggesting negative effect of increasing variability of precipitation on growth. Thus, the differences in height growth intensity might be related to growth sensitivity to weather conditions. On the other hand, such differences in height growth between clones might be caused by competition (i.e. with herbs), as trees with early leaf flushing might conquer more resources and become more robust against the environmental fluctuation.
  • Jansons, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: aris.jansons@silava.lv
  • Zeps, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: martins.zeps@silava.lv
  • Rieksts-Riekstiņš, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: Juris.Riekstins@silava.lv
  • Matisons, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: robism@inbox.lv (email)
  • Krišāns, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: oskars.krisans@silava.lv
article id 964, category Research article
Liisa Huttunen, Matthew P. Ayres, Pekka Niemelä, Susanne Heiska, Riitta Tegelberg, Matti Rousi, Seppo Kellomäki. (2013). Interactive effects of defoliation and climate change on compensatory growth of silver birch seedlings. Silva Fennica vol. 47 no. 3 article id 964. https://doi.org/10.14214/sf.964
Highlights: The main components affecting growth compensation in silver birch seedlings are the timing and severity of foliage damage; The ability to compensate growth is also dependent upon the limits of temperature and nutrient availability; The responses of birches imply that folivory does not necessarily lead to reduced net productivity under changing climate
Atmospheric warming increases the abundance of insect herbivores and intensifies the risk of defoliation, especially in high latitude forests. At the same time, the effects of increasing temperature and CO2 on plant responses to foliage damage are poorly understood. We examined if previous-year defoliation, varying between 0 and 75% of total leaf area, and different combinations of elevated temperature, CO2 and nutrient availability alter the growth of two-year old silver birch (Betula pendula Roth) seedlings. We measured the greatest height growth in seedlings that were fertilized and defoliated twice at the level of 50% of total leaf area, and subjected to elevated temperature with ambient CO2. The lowest growth was recorded in unfertilized seedlings that were defoliated twice at the level of 25% of total leaf area, and grew under ambient temperature with ambient CO2. The total biomass increased in all seedlings that were fertilized or grew under elevated temperature. The root: shoot ratios were low in defoliated seedlings, or seedlings subjected to fertilization or temperature elevation. Our conclusion is that ability of birches to compensate height growth is highly dependent upon the magnitude and frequency of defoliation on the limits of temperature and nutrient availability. These responses imply that folivory does not necessarily lead to reduced net productivity of trees under changing climate.
  • Huttunen, Section of Ecology, Department of Biology, University of Turku, FI-20014 Turku, Finland ORCID ID:E-mail: liisa.huttunen@utu.fi (email)
  • Ayres, Biological Sciences, Dartmouth College, Hanover, NH 03755, USA ORCID ID:E-mail: matt.ayres@dartmouth.edu
  • Niemelä, Section of Biodiversity and Environmental Science, Department of Biology, University of Turku, FI-20014 Turku, Finland ORCID ID:E-mail: pekka.niemela@utu.fi
  • Heiska, The Finnish Forest Research Institute, Punkaharju Unit, Finlandiantie 18, FI-58450 Punkaharju, Finland ORCID ID:E-mail: susanne.heiska@metla.fi
  • Tegelberg, Digitarium - Digitization Centre of the Finnish Museum of Natural History and the University of Eastern Finland, Joensuu Science Park, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: riitta.tegelberg@helsinki.fi
  • Rousi, The Finnish Forest Research Institute, Vantaa Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: matti.rousi@metla.fi
  • Kellomäki, Faculty of Science and Forestry, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: seppo.kellomaki@uef.fi
article id 932, category Research article
Jun Wang, Le Shi, Shaoyu Song, Ju Tian, Xiangyang Kang. (2013). Tetraploid production through zygotic chromosome doubling in Populus. Silva Fennica vol. 47 no. 2 article id 932. https://doi.org/10.14214/sf.932
The most direct approach in breeding triploid Populus is crossing allotetraploids with diploids. However, the lack of allotetraploid Populus restricts application of this approach. In this investigation, zygotic chromosome doubling was induced with colchicine and high temperatures to produce ((Populus pseudo-simonii × P. nigra ‘Zheyin3#’) × (P. × beijingensis)) allotetraploids. We screened 6 and 25 tetraploid individual offspring from the colchicine and high-temperature treatments respectively, indicating that both colchicine and high temperature are effective for tetraploid production by zygotic chromosome doubling of Populus. Developmental characteristics of seed hairs in the ovaries were temporally associated with zygotic development, which was used to successfully guide the colchicine and high-temperature treatments. During certain stages of hair development, the efficiency of tetraploid production was significantly high. However, efficiency of production was not significantly influenced by other factors, i.e. colchicine concentration, temperature or duration of high-temperature treatment. Size and frequency of leaf stomata between tetraploid and diploid plants were significantly different, suggesting that this character can be altered via genomic increase in material. The allotetraploids produced in this investigation, having different genotypes, provide important parental germplasms for further triploid breeding.
  • Wang, National Engineering Laboratory for Tree Breeding; Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education; College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P.R. China ORCID ID:E-mail: wangjun@bjfu.edu.cn (email)
  • Shi, National Engineering Laboratory for Tree Breeding; Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education; College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P.R. China ORCID ID:E-mail: 7320932@qq.com
  • Song, National Engineering Laboratory for Tree Breeding; Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education; College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P.R. China ORCID ID:E-mail: angela-song@foxmail.com
  • Tian, National Engineering Laboratory for Tree Breeding; Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education; College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P.R. China ORCID ID:E-mail: 1215813245@qq.com
  • Kang, National Engineering Laboratory for Tree Breeding; Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education; College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P.R. China ORCID ID:E-mail: kangxy@bjfu.edu.cn
article id 455, category Research article
Seppo Kellomäki, Matti Maajärvi, Harri Strandman, Antti Kilpeläinen, Heli Peltola. (2010). Model computations on the climate change effects on snow cover, soil moisture and soil frost in the boreal conditions over Finland. Silva Fennica vol. 44 no. 2 article id 455. https://doi.org/10.14214/sf.455
This study considered how climate change affects the accumulation of snow, the soil moisture and soil frost at sites without tree cover in boreal conditions in Finland (60°–70°N). An increase of 4.5 °C in annual mean temperature and 20 % in annual precipitation were assumed for Finland by the year 2100 according to A2 emission scenario. Along with climate, the soil type of the permanent inventory plots of the Finnish National Forest Inventory was used. Soil and climate data were combined by using a process-based ecosystem model. Calculations were done for four periods: current climate (1971–2000), near future (2001–2020), mid-term future (2021–2050) and long-term future (2071–2100). According to our simulations, the average monthly duration and depth of snow decreased over the simulation period. However, the increasing precipitation may locally increase the snow depths in the mid-term calculations. In the autumn and winter, the average volumetric soil moisture content slightly increased in southern Finland during the near future, but decreased towards the end of the century, but still remained on a higher level than presently. In northern Finland, the soil moisture in the autumn and winter increased by the end of this century. In the summertime soil moisture decreased slightly regardless of the region. Throughout Finland, the length and the depth of soil frost decreased by the end of the century. In the south, the reduction in the depth was largest in the autumn and spring, while in the mid-winter it remained relatively deep in the middle of the century. In the north, the depth tended to increase during the first two calculation periods, in some areas, even during the third calculation period (2071–2100) due to reduced insulation effects of snow during cold spells. The wintertime increase in soil moisture and reduced soil frost may be reflected to reduced carrying capacity of soil for timber harvesting.
  • Kellomäki, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail: seppo.kellomaki@uef.fi (email)
  • Maajärvi, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
  • Strandman, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
  • Kilpeläinen, 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:
article id 159, category Research article
Johan Stendahl, Maj-Britt Johansson, Erik Eriksson, Åke Nilsson, Ola Langvall. (2010). Soil organic carbon in Swedish spruce and pine forests – differences in stock levels and regional patterns. Silva Fennica vol. 44 no. 1 article id 159. https://doi.org/10.14214/sf.159
The selection of tree species is one factor to consider if we want to mitigate carbon dioxide emissions to the atmosphere through forest management. The objectives of this study were to estimate the differences in soil organic carbon (SOC) stocks under Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) forests and to examine causes of differences in the accumulation of carbon in the forest soil. Large-scale inventory data was used to quantify variations in SOC stock in relation to stand type and the accumulation of carbon for spruce and pine stands was analysed by simulation. Based on field data, the national mean SOC stock was 9.2 kg m–2 in spruce dominated stands and 5.7 kg m–2 in pine dominated stands. For both species, the SOC stock, measured in the field inventory, increased significantly with increasing temperature, although at different rates. The SOC stock was larger for spruce under all temperature conditions, but the difference between species diminished with increasing temperature. The simulations indicated that the build-up of SOC over several rotations was 22% higher in spruce stands than in pine stands under similar environmental conditions. The main difference was found to be the greater input of harvest residues for spruce. Further, the simulations showed that ground vegetation contributed considerably more to the litter production under pine than under spruce. On sites where both Scots pine and Norway spruce are considered suitable, the latter should be selected if the aim of the forest management policy is to maximize the accumulation of SOC in the forest. Further, spruce is more favourable for SOC accumulation in areas with cold temperatures and on sites with low productivity.
  • Stendahl, Department of Soil and Environment, P.O. Box 7001, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden ORCID ID:E-mail: johan.stendahl@mark.slu.se (email)
  • Johansson, Department of Soil and Environment, P.O. Box 7001, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden ORCID ID:E-mail:
  • Eriksson, Department of Energy and Technology, P.O. Box 7061, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden ORCID ID:E-mail:
  • Nilsson, Department of Soil and Environment, P.O. Box 7001, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden ORCID ID:E-mail:
  • Langvall, Unit for Field-based Forest Research, Asa Experimental Forest and Research Station, Swedish University of Agricultural Sciences, SE-36030 Lammhult, Sweden ORCID ID:E-mail:
article id 207, category Research article
Mats T. Olsson, Maria Erlandsson, Lars Lundin, Torbjörn Nilsson, Åke Nilsson, Johan Stendahl. (2009). Organic carbon stocks in Swedish Podzol soils in relation to soil hydrology and other site characteristics. Silva Fennica vol. 43 no. 2 article id 207. https://doi.org/10.14214/sf.207
Site characteristics influence soil organic carbon (SOC) stocks. In Podzols under Swedish forest land, SOC stocks were related to latitude, altitude, soil hydrological class categorized by mean groundwater level, mean annual precipitation, temperature sum during the growing season, total annual nitrogen (N) deposition and site capacity. SOC stocks were determined for the O-horizon and for total soil (O-horizon + mineral soil to a depth of 50 cm). Data from the Swedish National Forest Soil Inventory 1993–2001 were used (1477 field plots). The O-horizon was sampled with a core sampler and carbon (C) stocks were determined. For the mineral soil layers the SOC stock was calculated based on the SOC concentrations, bulk density and content of rock fragments. The results showed that the overall mean SOC stock was 2.8 and 8.2 kg C m–2 for O-horizon and total soil, respectively. Soil hydrological class strongly affected SOC stocks, which increased from on average 6.7 kg C m–2 at dry sites to 9.7 kg C m–2 at slightly moist sites. Corresponding values for the O-horizon were 2.0 to 4.4 kg C m–2. The correlation coefficients for the linear relationship between SOC stock and site characteristics were highest for N deposition, which explained up to 25% of variation, and latitude, which explained up to 20% of variation. Altitude had the lowest degree of explanation.
  • Olsson, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden ORCID ID:E-mail:
  • Erlandsson, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden ORCID ID:E-mail:
  • Lundin, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden ORCID ID:E-mail:
  • Nilsson, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden ORCID ID:E-mail: torbjorn.nilsson@mark.slu.se (email)
  • Nilsson, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden ORCID ID:E-mail:
  • Stendahl, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden ORCID ID:E-mail:
article id 230, category Research article
Risto Jalkanen, Sheila Hicks, Tarmo Aalto, Hannu Salminen. (2008). Past pollen production reconstructed from needle production in Pinus sylvestris at the northern timberline: a tool for evaluating palaeoclimate reconstructions. Silva Fennica vol. 42 no. 4 article id 230. https://doi.org/10.14214/sf.230
Annual needle production (PROD) of Scots pine (Pinus sylvestris L.) and pine pollen accumulation rates (PAR) are compared along a 5-site transect from the Arctic Circle to the northern timberline. PROD is calculated using the Needle Trace Method (NTM). PAR is monitored by two series of pollen traps, located in the centres of mires and within forests, respectively. There is a strong year-to-year agreement in PAR and PROD between the sites for the common 19-year period for which both proxies are available. Mean July temperature of the previous year (TJUL–1) correlates statistically significantly with PROD at all five sites and with PAR in the four northernmost sites. There is also a significant relationship between TJUN–1 and PROD at all sites, and TJUN and PAR at the two northernmost sites. PROD and PAR correlate most strongly in the three near tree line sites, where PROD explains up to 51% of the variation in PAR. On the basis of the calibration between PROD, PAR and TJUL–1, PROD and TJUL–1 are used to reconstruct past PAR. That such a reconstruction is realistic is supported by its agreement with the pollen record for 1982–2000 and with records of male flowering for the period 1956–1973. The use of PROD in reconstructing past PAR can help in interpreting the fossil pollen signal in terms of climate rather than vegetation change and in evaluating the high-resolution dating of peat profiles and calculations of the rate of peat accumulation.
  • Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: risto.jalkanen@metla.fi (email)
  • Hicks, Institute of Geosciences, P.O. Box 3000, FI-90014 University of Oulu, Finland ORCID ID:E-mail:
  • Aalto, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Salminen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
article id 293, category Research article
Conor O'Reilly, Norberto De Atrip. (2007). Seed moisture content during chilling and heat stress effects after chilling on the germination of common alder and downy birch seeds. Silva Fennica vol. 41 no. 2 article id 293. https://doi.org/10.14214/sf.293
The effects of seed moisture content (MC) and heat treatment on the germination response of common alder (Alnus glutinosa) and downy birch (Betula pubescens) seeds were examined. Seeds of each species were adjusted to MC of 7% to 50% MC, then chilled for up to 36 weeks, after which they were allowed to germinate at 15°C with 8 hours lighting per day or 20 (dark)/ 30°C (light). Seed lot effects were evident, but treatment effects were consistent in each lot and species. The response to moist chilling treatments was larger at 15°C than at 20/30°C. Chilling had no effect on germination unless seed MC was >15%, but it was low also at 20% MC. The highest germination was achieved following 24–36 weeks chilling at the optimum or target MC (TMC) levels of about 30% in alder and 35% in birch. In a separate experiment, seeds were fully imbibed (FI) (~50% MC; standard method used in operational practice) or adjusted to TMC levels, after which some seeds of each treatment group were chilled to release dormancy. Following this, the seeds were dried back to TMC levels and then subjected to 60°C for up to 4 hours after which they were allowed germinate under the same conditions described above. Heat treatment damaged the prechilled FI seeds, but no damage occurred to the non-chilled seeds. However, heat stress stimulated germination in the non-chilled FI seeds of both species and the TMC seeds of alder.
  • O'Reilly, UCD School of Biology and Environmental Science, UCD College of Life Sciences, University College Dublin, Belfield, Dublin 4, Ireland ORCID ID:E-mail: conor.oreilly@ucd.ie (email)
  • De Atrip, UCD School of Biology and Environmental Science, UCD College of Life Sciences, University College Dublin, Belfield, Dublin 4, Ireland ORCID ID:E-mail:
article id 305, category Research article
Anna-Maria Veijalainen, Marja-Liisa Juntunen, Arja Lilja, Helvi Heinonen-Tanski, Leo Tervo. (2007). Forest nursery waste composting in windrows with or without horse manure or urea – the composting process and nutrient leaching. Silva Fennica vol. 41 no. 1 article id 305. https://doi.org/10.14214/sf.305
In order to find the best management practices for forest nursery waste composting, organic waste was composted without or with horse manure or urea in six windrows for two years. The windrows were built in four consecutive years during 1999–2002. In 1999, no extra-nutrients were added to the windrow (N99). In 2000, urea fertilizer was used as a nitrogen source (U00). Despite this, the process did not function properly. In 2001, two windrows were built, one (H01) with and the other (N01) without horse manure. Horse manure slightly accelerated the heating process. Consequently, two windrows with more horse manure were built in 2002. One was aerated passively (H02) as earlier windrows, and the other was aerated forcedly (HA02). Horse manure and forced aeration were needed to keep the temperature above 55°C for long enough to ensure microbial hygiene of the material. The degradation of cellulose was greater during the curing stage. Nutrient leaching was low, although the additives increased leaching in conjunction with the inefficient process. The results showed that forest nursery waste alone is ineffective at raising the temperature of the compost, and degrades slowly due to its low nutrient and easily available carbon content. The best management practice for forest nursery waste composting is to use horse manure and aeration to ensure the heating process. Environmental contamination can be avoided by collecting the leachates. Further research is needed to evaluate the usability of the compost.
  • Veijalainen, Finnish Forest Research Institute, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Juntunen, Finnish Forest Research Institute, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Lilja, Finnish Forest Research Institute, PO Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
  • Heinonen-Tanski, Univ. of Kuopio, Dept. of Environm. Sc., PO Box 1627, FI-70211 Kuopio, Finland ORCID ID:E-mail:
  • Tervo, Finnish Forest Research Institute, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
article id 328, category Research article
Pedro J. Aphalo, Markku Lahti, Tarja Lehto, Tapani Repo, Aino Rummukainen, Hannu Mannerkoski, Leena Finér. (2006). Responses of silver birch saplings to low soil temperature. Silva Fennica vol. 40 no. 3 article id 328. https://doi.org/10.14214/sf.328
Two-year-old silver birch (Betula pendula) saplings were grown for a third growing season in controlled-environment rooms (dasotrons) at three soil temperatures (5, 10, and 20 °C). All trees grew the first flush of leaves, but the growth of the second flush was almost completely inhibited at the two lower temperatures. The dry weight of the second-flush leaves was 50 times larger at 20 °C than at 5 and 10 °C, with about 100 times more nitrogen. Root growth was less affected than shoot growth. Chlorophyll content, net assimilation rate and stomatal conductance were lower at low soil temperatures. The value of the cytoplasm resistance estimated from the electric impedance spectra was lower at 5 °C than at 10 or 20 °C. Leaf water potential was highest at the lowest soil temperature, and intercellular carbon dioxide concentration was only slightly lower in saplings growing in cooler soil. We conclude that the effect of long-term exposure to cold soil on net assimilation and growth was not caused by stomatal closure alone. It is likely to be additionally mediated by the limited nitrogen acquisition at the low soil temperatures, and perhaps additionally by some other factor. As the growth depression of aboveground parts in response to low soil temperature was more significant in silver birch than what has earlier been found in conifers, the relative changes in air and soil temperature may eventually determine whether birch will become more dominant in boreal forests with climate change.
  • Aphalo, University of Helsinki, Department of Biological and Environmental Sciences ORCID ID:E-mail:
  • Lahti, The Finnish Forest Research Institute ORCID ID:E-mail:
  • Lehto, University of Joensuu, Faculty of Forestry, Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: tarja.lehto@joensuu.fi (email)
  • Repo, The Finnish Forest Research Institute ORCID ID:E-mail:
  • Rummukainen, University of Joensuu, Faculty of Forestry, Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Mannerkoski, University of Joensuu, Faculty of Forestry, Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Finér, The Finnish Forest Research Institute ORCID ID:E-mail:
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 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 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 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: Research note

article id 960, category Research note
Shou-Qin Sun, Liang Peng, Gen-Xu Wang, Yan-Hong Wu, Jun Zhou, Hai-Jian Bing, Dong Yu, Ji Luo. (2013). An improved open-top chamber warming system for global change research. Silva Fennica vol. 47 no. 2 article id 960. https://doi.org/10.14214/sf.960
This study is an assessment of an improved temperature warming system developed to enhance global warming research-based forest ecosystem and soil ecophysiological experiments. The architecture couples a standard open-top chamber (OTC) with a heating cable. A 16 m wire cable with an 18 W m-1 and 288 W h-1 power rating was coiled around a polyvinyl chloride (PVC) pipe 2.5 m in length and 3.5 cm in diameter. The pipe was reshaped into a circle and fixed inside the OTC at a height of 15 cm. PVC pipe distance to plants was 10 to 15 cm while distance to OTC inner walls was 15 cm. The cable was constructed from a heating source with an alloy resistance wire, an aluminum foil and copper wire shielded layer, a crosslinking polyethylene inner insulator, a PVC coating, and a tinned copper grounding wire. After the cable is powered up, air and soil inside the OTC-cable system is heated by conductivity. Temperature is manipulated according to the voltage and resistance of the cable. The OTC-cable system was developed to examine plant reaction to an increase in air and soil temperatures by 2.84 °C and 1.83 °C, respectively. Temperature values are adjustable by changing cable and PVC pipe length. It offers a new, affordable, low energy consumption and low running cost method by which to study climate change effects on forest ecosystems. This method is especially useful for application in forest ecosystems of many developing countries or in many remote areas of developed countries where the feasibility in supplying sufficient power from local power grids is questionable.
  • Sun, Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, No. 9, Block 4, South Renmin Road, Chengdu, China, 610041 ORCID ID:E-mail: shouqinsun@imde.ac.cn (email)
  • Peng, Horticulture and Landscape College, Hunan Agricultural University, Furong District, Changsha, China, 410128 ORCID ID:E-mail: keith215@126.com
  • Wang, Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China ORCID ID:E-mail: cookiedot@sina.cn
  • Wu, Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China ORCID ID:E-mail: free2001@tom.com
  • Zhou, Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China ORCID ID:E-mail: haitaosun@sohu.com
  • Bing, Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China ORCID ID:E-mail: 78186181@qq.com
  • Yu, Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China ORCID ID:E-mail: dongdyu@sohu.com
  • Luo, Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China ORCID ID:E-mail: 1254157095@qq.com

Category: Article

article id 7144, category Article
Leo Heikurainen, Kustaa Seppälä. (1963). Kuivatuksen tehokkuus ja turpeen lämpötalous. Acta Forestalia Fennica vol. 76 no. 4 article id 7144. https://doi.org/10.14214/aff.7144
English title: The effect of drainage degree on temperature conditions of peat.

The determination of biologically most favourable strip width in peatlands to be drained has been hindered by lack of information of the temperature conditions in the surface peat and in the air close to the ground after drainage of different intensities. Temperature measurements were carried out on peatlands drained to different degrees in Central Finland in the summers of 1960 and 1961. The ground water level in the measuring points, and the strip width served as the criterion for differences in water condition.

When the drainage became more intensive, the temperature of the surface peat decreased. However, temperature differences were small, and discernible only when the differences of water conditions were considerable. The effect of strip condition to temperature seems to be of similar nature than the ground water level. Even in extreme cases temperature differences due to different drainage intensity were relatively small, and seldom exceeded 2°C.

Differences in temperature dependent on the growing stock may be as high as 10°C. Thus, the temperature of the surface peat may be dependent on factors more important than temperature differences caused by aspects of drainage. A well-drained peatland is coldest at the beginning of a growing season compared with poorly drained peatland. The temperature differences increase deeper in the peat. This is caused by the better heat conductivity of the moist peat. Also, daily variations in temperature in the surface peat are large in moist peat.

The PDF includes a summary in English.

  • Heikurainen, ORCID ID:E-mail:
  • Seppälä, ORCID ID:E-mail:
article id 7450, category Article
J. Keränen. (1954). Lämmityskausi ja sen lämpötekijät Suomen ilmastossa. Acta Forestalia Fennica vol. 62 no. 1 article id 7450. https://doi.org/10.14214/aff.7450
English title: Heating season and factors affecting temperature in Finnish climate.
Original keywords: lämmitys; ilmasto; Suomi; lämpötilat

The aim of the investigation was to estimate the effect of climate on the temperature observations and heating of buildings. Temperature data of observation stations in Finland and in the neighbouring countries near Finnish borders, in all 190 stations, was collected during heating season. 

Heating season begins in the northern border of Finland in 20th of July,  in Rovaniemi oin the Northern Finland in the middle of August, and 5th of September in the Southern coast of the country. Similarly, the heating season ends in 2.-10.6. in Southern and Central Finland, in June in Northern Finland, and in the middle of June in the Northernmost Finland, where heating season continued almost the whole year. In Southern Finland the length of heating season was 280 days. In the coldest heating season in 1942-1942 the heating decree-days increased most in the province of Varsinais-Suomi in Southern Finland. The increase decreased towards North. In the warmest heating season in 1929-1930 decrease of heating decree-days was similar in almost the whole country. The data can be used to define how different weather conditions affect the need of fuel.  

The PDF includes a summary in German. 

  • Keränen, 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 7303, category Article
J. Keränen. (1934). Lämpöoloista puiden ja eräiden pensaiden kasvupaikkojen pohjoisilla rajoilla Suomessa. Acta Forestalia Fennica vol. 40 no. 26 article id 7303. https://doi.org/10.14214/aff.7303
English title: Thermal conditions in the northern limits of some tree species and bushes in Finland.

The article discusses the thermal conditions in the northern limits of trees and some bushes in Finland. Temperature is the most important limiting factor for distribution of plant species. Precipitation variations, however, are small in Finland. The article lists the main features of thermal conditions during the different seasons in different parts of Finland. The northern limits and the thermal condition of the area are described for the following species: Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.), mezereon, buckthorn, common alder, linden, elm, maple, hazel, ash, oak, hybrid mountain ash, yew and Swedish whitebeam.

The PDF includes a summary in English.

  • Keränen, 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 5606, category Article
Pekka E. Kauppi, Pekka Hänninen, Helena M Henttonen, Antti Ihalainen, Eino Lappalainen, Maximilian Posch, Michael Starr, Pekka Tamminen. (1997). Carbon reservoirs in peatlands and forests in the boreal regions of Finland. Silva Fennica vol. 31 no. 1 article id 5606. https://doi.org/10.14214/sf.a8507

The carbon reservoir of ecosystems was estimated based on field measurements for forests and peatlands on an area in Finland covering 263,000 km2 and extending about 900 km across the boreal zone from south to north. More than two thirds of the reservoir was in peat, and less than ten per cent in trees. Forest ecosystems growing on mineral soils covering 144,000 km2 contained 10–11 kg C m-2 on an average, including both vegetation (3.4 kg C m-2) and soil (uppermost 75 cm; 7.2 kg C m-2). Mire ecosystems covering 65,000 km2 contained an average of 72 kg C m-2 as peat. For the landscape consisting of peatlands, closed and open forests, and inland water, excluding arable and built-up land, a reservoir of 24.6 kg C m-2 was observed. This includes the peat, forest soil and tree biomass. This is an underestimate of the true total reservoir, because there are additional unknown reservoirs in deep soil, lake sediments, woody debris, and ground vegetation. Geographic distributions of the reservoirs were described, analysed and discussed. The highest reservoir, 35–40 kg C m-2, was observed in sub-regions in central western and north western Finland. Many estimates given for the boreal carbon reservoirs have been higher than those of ours. Either the Finnish environment contains less carbon per unit area than the rest of the boreal zone, or the global boreal reservoir has earlier been overestimated. In order to reduce uncertainties of the global estimates, statistically representative measurements are needed especially on Russian and Canadian peatlands.

  • Kauppi, ORCID ID:E-mail:
  • Hänninen, ORCID ID:E-mail:
  • Henttonen, ORCID ID:E-mail:
  • Ihalainen, ORCID ID:E-mail:
  • Lappalainen, ORCID ID:E-mail:
  • Posch, ORCID ID:E-mail:
  • Starr, ORCID ID:E-mail:
  • Tamminen, 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 5582, category Article
Jonathan J. Ruel, Matthew P. Ayres. (1996). Variation in temperature responses among populations of Betula papyrifera. Silva Fennica vol. 30 no. 2–3 article id 5582. https://doi.org/10.14214/sf.a9227

How will global warming affect southern populations of boreal trees? In paper birch, Betula papyrifera (Betulaceae), alpine trees with an evolutionary history of relatively cool summers may be more sensitive to climate warming than valley populations. We evaluated this scenario by growing seedlings from different populations in four temperature treatments (mountain field site, valley field site, and two greenhouse rooms).

Populations from low elevations germinated earlier and had higher germination success than population from high elevations (16.8 vs. 22.0 d; 72% vs. 11%). At the valley site, seedlings from native populations grew faster than seedlings from higher elevations (mean ± SE = 0.25 ± 0.02 vs. 0.09 ± 0.04 mm · cm-1 · d-1) while at the mountain site, all seedlings grew at similar rates. Seedling grown in cooler environments had higher root : shoot ratios, perhaps to compensate for temperature limitations in nutrient uptake by roots. Leaf area varied among populations but was not affected by environmental differences across the field sites. Net photosynthetic rates at valley temperatures were higher for seedlings grown in the valley than for seedling grown in the mountains or the warm greenhouse (12.0 vs. 10.3 and 5.8 μmoles · m-2 · s-1), perhaps due to adaptive phenotypic adjustments. Climatic warming could rapidly produce important phenotypic changes in birch trees (e.g. decreased root : shoot ratio, reduced growth in alpine populations). On a longer time-scale, warming could also result in genetic changes as natural selection favours valley genotypes in alpine sites where they are presently rare.

  • Ruel, ORCID ID:E-mail:
  • Ayres, ORCID ID:E-mail:
article id 5581, category Article
Oddvar Skre, Knut Nes. (1996). Combined effects of elevated winter temperatures and CO2 on Norway spruce seedlings. Silva Fennica vol. 30 no. 2–3 article id 5581. https://doi.org/10.14214/sf.a9226

A total of 1,800 3-year old seedlings of Norway spruce (Picea abies (L.) H. Karst.) from two Norwegian and one German provenance were treated with two different nitrogen levels during the 1992 growth season. The plants were kept during the following winter at two different temperature levels. In the spring of 1993, the nutrient application was resumed, and the plants were divided between three different treatments, 350 and 650 p.p.m. in open top chamber and a control plot outside the chambers. This treatment was repeated also during the following 1994 growth season.

The growth and primary production were studied by photosynthesis experiments and by non-destructive growth measurements. The result indicate that raised winter temperature may lead to increased needle loss and reduced growth the following season, particularly in northern provenances. Carbon dioxide significantly influenced growth in addition to nutrient level and winter temperature. High CO2 also seemed to cause increased photosynthesis at early season, and earlier budbreak and growth cessation than in control plants.

  • Skre, ORCID ID:E-mail:
  • Nes, ORCID ID:E-mail:
article id 5536, category Article
Roar Skuterud, Jon Dietrichson. (1994). Budburst in detached birch shoots (Betula pendula) of different varieties winter-stored in darkness at three different temperatures. Silva Fennica vol. 28 no. 4 article id 5536. https://doi.org/10.14214/sf.a9176

Budburst timing and the relationship to storage temperature and duration were investigated in four varieties (entries) of 1–2 metres tall silver birch (Betula pendula Roth) trees. A total of 2,160 shoots were sampled, and the material stores in darkness at 0, 3 or 6 °C from November 29, 1993. When the shoots were placed in storage, they had been through a period of 29 days with temperatures below 0°C (since October 15). By that time the autumn dormancy was assumed already broken, and the trees were expected to respond to increased temperature by bud development. On January 4, 1994, and on four subsequent dates, January 19, February 1, March 4 and March 17, shoots were taken out of storage and set in growth chambers at 9, 12 or 15°C. The time to budburst was recorded.

Duration of storage, storage temperatures and varieties were all highly significant for budburst. The interaction terms were of less statistical importance. Based on the contrast between the three different growth chamber environments, three different methods were used to calculate the threshold temperatures for each entry. In spite of the pre-selection of variable budburst performers, the threshold values, varying between 0°C to -2°C, could not be shown to be statistically different. According to the results, the time of budburst changes in accordance with both winter and spring temperatures, being extremely early after a mild winter and warm spring, given sufficient autumn chilling. The similarities in the threshold temperatures indicate that the ranking in earliness between varieties will most likely be the same from year to year without regard to climate change.

  • Skuterud, ORCID ID:E-mail:
  • Dietrichson, ORCID ID:E-mail:
article id 5534, category Article
Hyun Kang, Inger Ekberg, Gösta Eriksson, Johan Ununger. (1994). Second and third growth period responses of Picea abies families to first growth period photoperiodic, light intensity and temperature treatments. Silva Fennica vol. 28 no. 4 article id 5534. https://doi.org/10.14214/sf.a9174

Seedlings of Picea abies (L.) H. Karst. full-sib families of contrasting origins were cultivated in a phytotron under different photoperiodic, light-intensity and temperature treatments during their first growth period. The effects of the treatments on juvenile growth traits – whether enhanced or delayed maturation was induces – were observed during the two subsequent growth periods. The following hypotheses were tested: (A) Enhanced maturation can be induced in the first growth period from sowing with (i) a long period of continuous light during active growth (24 weeks vs. 8 weeks); (ii) a shorter night during bud maturation (12 h vs. 16 h); high temperature (25°C vs. 20°C) during (iii) active growth, growth cessation and bud maturation; and during (iv) the latter part of growth cessation and bud maturation only. (B) Delayed maturation can be induced after (i) low light intensity during growth cessation and bud maturation (114 μmol m-2 s-1 vs. 340 μmol m-2 s-1); low temperature (15°C vs. 20°C) during (ii) active growth, growth cessation and bud maturation; and during (iii) the latter part of growth cessation and bud maturation only.

The most dramatic effect was observed after 24 weeks of continuous light during active growth. All traits showed a significantly more mature performance in the second growth period compared with the control. The effect for all but one trait was carried over to the third growth period. This is in accordance with the hypothesis that the activity of apical shoot meristems controls the maturation process. For the other treatments there was only weak or no support for the hypothesis of induction of enhanced or delayed maturation. Strong family effects were observed for all traits. Differential responses of the various latitudinal families were observed, suggesting that family effects must be considered to predict and interpret correctly how plants will respond to environmental effects.

  • Kang, ORCID ID:E-mail:
  • Ekberg, ORCID ID:E-mail:
  • Eriksson, ORCID ID:E-mail:
  • Ununger, ORCID ID:E-mail:
article id 5533, category Article
Reijo Solantie. (1994). Effect of weather and climatological background on snow damage of forests in Southern Finland in November 1991. Silva Fennica vol. 28 no. 3 article id 5533. https://doi.org/10.14214/sf.a9173

Snow damage to forests in Southern Finland in November 1991 was examined in relation to meteorological conditions. The combined effect of different factors proved to be necessary for severe damage. First, the snow load, in terms of precipitation, should exceed a certain limit. The limit can be set for weak or moderate damage at about 40 mm and for very severe damage at about 60 mm. Second, temperature at the time of precipitation should be above 0°C, which enables the slightly wet snow to attach to twigs during the subsequent period with temperature below 0°C. On the other hand, temperatures exceeding 0.6°C prohibit damage by permitting the snow load to fall from the branches. Wind speed exceeding 9 ms-1, as observed 15 m above ground, were strong enough to dislodge the snow which is not attached, and thus reduce the damage. There are few statistics either of snow damage or of the relation between the snow damage and precipitation. However, there is causal connection between snow damage and heavy snowfalls. Therefore, the regions with a high frequency of heavy snowfalls, as indicated by orographical features and occurrence of thick snow cover, were investigated.

  • Solantie, 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 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 5409, category Article
Jukka Lippu, Pasi Puttonen. (1990). Istutustaimen juuriston alkukehitys kasvupaikalla. Silva Fennica vol. 24 no. 1 article id 5409. https://doi.org/10.14214/sf.a15561
English title: The early development of seedling roots at the planting site: A literature review.

The structure and functional responses of roots in planted seedlings when acclimatizing at the planting site are reviewed. A wide range of methods for classifying roots has been employed, and the terminology used is not uniform. Roots can be classified by their morphology, origin, and function. The temporal and spatial variation of soil temperature, moisture, structure, and concentration of nutrients are among the most important properties to which root systems acclimatize. In order to reliably describe the function of the root system, several parameters usually have to be measured. Studies on the root-soil interface have indicated that roots are not necessarily in continuous contact with soil. The control mechanism of root growth is inadequately known and theoretically formulated. Generally, only the mass needed for water and nutrient uptake has been allocated to the roots. However, the amount of photosynthates allocated to the roots is high. Acclimatization of seedlings out at the planting site is a complicated process which is influenced by the growing conditions at both the nursery and at the site. The function, distribution and structure of roots are controlled by the environment in a way similar to the shoot, but the control mechanism is imperfectly known.

The PDF includes an abstract in English.

  • Lippu, ORCID ID:E-mail:
  • Puttonen, ORCID ID:E-mail:
article id 5407, category Article
Eero Kubin. (1990). Lumi-, routa- ja lämpöolot eri tavoin muokatussa metsämaassa Kuusamossa. Silva Fennica vol. 24 no. 1 article id 5407. https://doi.org/10.14214/sf.a15559
English title: The effect of site preparation on snow, soil frost and temperature conditions at a site near Kuusamo.

The winter 1986–87 was unusually cold; the snow cover remained thin and consequently the soil froze to a considerable depth. In spite of the severe frost, the lowest temperatures measured at the ground surface was -10.3°C and in the soil at the depth of 10 cm -5.8°C. The temperature sum of the following summer was unusually small and the soil frost melted more slowly than usual. The winter frosts did not have a decisive influence on the survival of planted seedlings.

The PDF includes an abstract in English.

  • Kubin, ORCID ID:E-mail:
article id 5360, category Article
Risto Rikala, Pasi Puttonen. (1988). Maan lämpötilan vaikutus kuivuusrasitukseen perustuvassa taimien laatutestissä. Silva Fennica vol. 22 no. 4 article id 5360. https://doi.org/10.14214/sf.a15517
English title: Effect of soil temperature in drought exposure-based test of seedling quality.

The effect of root exposure on the shoot and root development of Pinus sylvestris (L.) seedlings was studied at two soil temperatures. Roots of bare-rooted three-year-old seedlings were exposed to the temperature of 32°C at relative humidity of 50–40% for 85, 155 and 270 minutes which corresponds to accumulated water pressure deficit of 24, 47 and 91 mbar·h, respectively. Thereafter, seedlings were grown for 65 days at the soil temperatures of 12 and 23°C. Drought exposures inhibited new root initiation, delayed shoot elongation, and reduced shoot and needle growth. The stronger the exposure the larger the proportion of needles from the lower part of current shoot that remained undeveloped. Low soil temperature increased the effect of exposures so that needle elongation and initiation of new root tips of seedlings in cold soil with the longest exposure were inhibited totally. Root growth assessments made in warm soil may overestimate the acclimation potential of planted seedlings.

The PDF includes an abstract in English.

  • Rikala, ORCID ID:E-mail:
  • Puttonen, ORCID ID:E-mail:
article id 5351, category Article
Tapani Repo. (1988). Physical and physiological aspects of impedance measurements in plants. Silva Fennica vol. 22 no. 3 article id 5351. https://doi.org/10.14214/sf.a15508

Electrical impedance characteristics of plant cells are dependent on such physiological factors as physiological condition, developmental stage, cell structure, nutrient status, water balance and temperature acclimation. In the measurements also such technical and physical factors as type of electrodes, frequency, geometry of the object, inter-electrode distance and temperature have an effect. These factors are discussed especially with respect to the impedance method in frost resistance studies of plants.

The PDF includes an abstract in Finnish.

  • Repo, ORCID ID:E-mail:
article id 5348, category Article
Risto Häkkinen, Pertti Hari. (1988). The efficiency of time and temperature driven regulation principles in plants at the beginning of the active period. Silva Fennica vol. 22 no. 2 article id 5348. https://doi.org/10.14214/sf.a15505

The distribution of the minimum temperatures after the beginning of the active period (one temperature for each spring) have been calculated for each principle using daily meteorological data collected during the years 1883–1980. The efficiency criterion is the variance of the minimum temperature distributions and the length of the active period. The most efficient regulation principle is found to be based on the temperature sum which includes a feedback component.

The PDF includes a summary in Finnish.

  • Häkkinen, ORCID ID:E-mail:
  • Hari, ORCID ID:E-mail:
article id 5319, category Article
Heikki Hänninen. (1987). Effects of temperature on dormancy release in woody plants. Silva Fennica vol. 21 no. 3 article id 5319. https://doi.org/10.14214/sf.a15476

Logical structure of three simulation models and one conceptual model concerning effects of temperature on dormancy release in woody plants was examined. The three basic types of simulation models differed in their underlying assumptions. Contrasting implications of the models were inferred by deduction. With the aid of these implications, the model types can be tested using experiments with continuous and interrupted chilling. Similarly, implications of the conceptual model of rest phases were inferred, by which the model can be tested using experiments with continuous chilling and forcing in multiple temperatures. The possibilities to synthetize the conceptual model with any of the three simulation model types, as well as the biological interpretation of the model variables, were discussed.

The PDF includes an abstract in Finnish.

  • Hänninen, 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 5257, category Article
Heikki Hänninen. (1986). Metsäpuiden vuosirytmitutkimuksen käsitteistä ja teorioista. Silva Fennica vol. 20 no. 1 article id 5257. https://doi.org/10.14214/sf.a15436
English title: Conceptual remarks about the study of the annual rhythm of forest trees.

Different approaches to the study of the annual rhythm of forest trees are described and compared by analysing the concepts and theories presented in the literature. The seasonality varying morphological and physiological state of forest trees is referred to as the annual rhythm s. lat., from which the annual ontogenetic rhythm is separated as a distinct type. The dormancy phenomena of the trees are grouped into four categories. Theories concerning the regulation of the annual rhythm are divided into two main types, the most common examples of which are the photoperiod theory and the temperature sum theory. Recent efforts towards a synthetic theory are described.

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  • Hänninen, ORCID ID:E-mail:
article id 5227, category Article
Harri Vasander, Tapio Lindholm. (1985). Tulen voimakkuus ja maanpinnan lämpötila kulotuksen aikana. Silva Fennica vol. 19 no. 1 article id 5227. https://doi.org/10.14214/sf.a15406
English title: Fire intensities and surface temperatures during prescribed burning.

Surface temperature during two prescribed burnings were measured in 1983 in Evo, Southern Finland. Surface temperatures in relation to the amount of slash burned, energy released during the fires, and the fire intensities were studied. The fire intensity was also measured during a third burn. The Lake Nimetön site was burned int the end of May. Due to the uneven distribution of slash, colonization by Calamagrostis arundinacea and the spring moisture, the burning was very uneven. Surface temperatures varied between 410–809°C and the intensity of fire was low (range 0–900 kW/m).

The fire intensity on the other sites burned in May was also low (880 kW/m). During the burn in August the surface temperatures varied between 701–869°C and the intensity of fire was moderate (1,170 kW/m). Slash was burned more evenly and more thoroughly due to the dryness of the site and slash and the fact that grasses and other herbs were not abundant.

The PDF includes a summary in Finnish.

  • Vasander, ORCID ID:E-mail:
  • Lindholm, ORCID ID:E-mail:
article id 5210, category Article
Heikki Smolander, Juha Lappi. (1984). The interactive effect of water stress and temperature on the CO2 response of photosynthesis in Salix. Silva Fennica vol. 18 no. 2 article id 5210. https://doi.org/10.14214/sf.a15389

The interactive effects of water stress and temperature on the CO2 response of photosynthesis was studied in Salix sp. cv. Aquatica using the closed IRGA system. A semi-empirical model was used to describe the CO2 response of photosynthesis. The interactive effect of water stress and temperature was divided into two components: the change in CO2 conductance and the change in the photosynthetic capacity. The CO2 conductance was not dependent on the temperature when the willow plant was well watered, but during water stress it decreased as the temperature increased. The photosynthetic capacity of the willow plant increased along with an increase in temperature when well-watered, but during water stress temperature had quite opposite effect.

The PDF includes a summary in Finnish.

  • Smolander, ORCID ID:E-mail:
  • Lappi, ORCID ID:E-mail:
article id 5183, category Article
Risto Ojansuu, Helena Henttonen. (1983). Kuukauden keskilämpötilan, lämpösumman ja sademäärän paikallisten arvojen johtaminen Ilmatieteen laitoksen mittaustiedoista. Silva Fennica vol. 17 no. 2 article id 5183. https://doi.org/10.14214/sf.a15099
English title: Estimation of the local values of monthly mean temperature, effective temperature sum and precipitation sum from the measurements made by the Finnish Meteorological Office.

Methods involving the use of moving averages, trend surfaces and their combination are compared in deriving local values of monthly mean temperatures and precipitation sums from the observations made by the Finnish Meteorological Office. Correlation between meteorological variables and sea index, lake index and height above sea level were used in the trend surface method and in the combined method. Combined method, with a trend surface calculated from means of a long time period, was the most reliable method to estimate long local time series.

A method to calculate unbiased estimates of effective temperature sums from monthly mean temperatures is presented.

The PDF includes a summary in English.

  • Ojansuu, ORCID ID:E-mail:
  • Henttonen, ORCID ID:E-mail:
article id 5183, category Article
Risto Ojansuu, Helena Henttonen. (1983). Kuukauden keskilämpötilan, lämpösumman ja sademäärän paikallisten arvojen johtaminen Ilmatieteen laitoksen mittaustiedoista. Silva Fennica vol. 17 no. 2 article id 5183. https://doi.org/10.14214/sf.a15099
English title: Estimation of the local values of monthly mean temperature, effective temperature sum and precipitation sum from the measurements made by the Finnish Meteorological Office.

Methods involving the use of moving averages, trend surfaces and their combination are compared in deriving local values of monthly mean temperatures and precipitation sums from the observations made by the Finnish Meteorological Office. Correlation between meteorological variables and sea index, lake index and height above sea level were used in the trend surface method and in the combined method. Combined method, with a trend surface calculated from means of a long time period, was the most reliable method to estimate long local time series.

A method to calculate unbiased estimates of effective temperature sums from monthly mean temperatures is presented.

The PDF includes a summary in English.

  • Ojansuu, ORCID ID:E-mail:
  • Henttonen, ORCID ID:E-mail:
article id 5133, category Article
F. Scholz. (1981). Genecological aspects of air pollution effects on northern forests. Silva Fennica vol. 15 no. 4 article id 5133. https://doi.org/10.14214/sf.a15360

Natural forest tree populations are adapted to their natural environment. Forest tree species under northern conditions are at the edge of their range where the short growing season and the low winter temperatures are the two main factors limiting their ecological niche. Effects of air pollution on the ecological niche, designated as the environmental conditions that permit a population to survive permanently, are discussed according to G.E. Hutchinson’s concept of the ecological niche. Air pollution as an additional stress factor influences the ecological niche either by the direct influence as an additional dimension of the ecological niche or by interaction with the other dimensions. These interactions are especially important for low level long-term effects of air pollution which can result in reduced resistance to low winter temperature or, due to reduced net assimilation, reduced capability to survive the long period of winter dormancy. These effects influence the boundary of the ecological niche and reduce the area of the biotope of the respective species.

Within the remaining biotope genetic changes in forest tree species take place. Due to individual differences in exposure and susceptibility of trees to air pollution, higher and therefore more exposed trees as well as more susceptible trees will be reduced in reproduction or even be eliminated. This causes genetic changes in the tree population.

  • Scholz, ORCID ID:E-mail:
article id 5109, category Article
Esteri Ohenoja, Liisa Pohjola. (1981). Metsämaan lämpöolojen mittaaminen ruokosokerin inversioon perustuvalla menetelmällä. Silva Fennica vol. 15 no. 2 article id 5109. https://doi.org/10.14214/sf.a15050
English title: Sucrose inversion method for measuring the temperature conditions in forest soil.

The use and problems of the sucrose inversion method for the study of forest humus and soil are discussed. The method is based on the temperature dependence of sucrose inversion, changes in rotation angle being determined with a circle polarimeter. Average temperatures and thermal sums for forest humus in different forests in Finland were measured, using this method, for a period of ca. 100 days. The results are not considered definitive but are regarded rather as examples. Average temperatures were somewhat higher in the humus of dry and poor heath forests than in that of moist and herb-rich forests, with exceptions that could be explicable by topographic position.

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  • Ohenoja, ORCID ID:E-mail:
  • Pohjola, ORCID ID:E-mail:
article id 5048, category Article
Seppo Kellomäki. (1979). The effect of solar radiation and air temperature on basic density of Scots pine wood. Silva Fennica vol. 13 no. 4 article id 5048. https://doi.org/10.14214/sf.a14905

The effect of solar radiation and air temperature on the basic density of Scots pine (Pinus sylvestris L.) wood has been investigated on the basis of material obtained from the literature. Solar radiation seemed to affect basic density during earlywood formation. Temperature had the greatest effect on basic density  in late summer. The varying effects of radiation and temperature seemed to be associated with the dynamics of the crown system of trees. Especially the capacity of the crown system to produce the amount of photosynthesis needed in tracheid growth is assumed to be of importance in controlling the variation in the basic density of Scots pine wood. Growth of thracheids from the point of view of photosynthate supply is discussed.

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  • Kellomäki, ORCID ID:E-mail:
article id 5015, category Article
Seppo Kellomäki. (1979). On geoclimatic variation in basic density of Scots pine wood. Silva Fennica vol. 13 no. 1 article id 5015. https://doi.org/10.14214/sf.a14869

The effect of temperature and water supply in the basic density of Scots pine (Pinus sylvestris L.) wood was studied on the basis of material obtained from the literature. On a monthly basis, the basic density increased with increasing mean temperature for June, July and August. The rainfall in these months had no detectable effect on the basic density except through the difference between rainfall and evaporation in July. On a yearly basis, the basic density increased with increasing mean temperature, temperature sum and length of growth period. The effect of water supply on the basic density was evident, and a linear relationship between basic density and annual rainfall was detected. The variation in basic density was, however, explained only partly by the chosen factors. Possible reasons for the poor explanatory power have been discussed.

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  • Kellomäki, ORCID ID:E-mail:
article id 4980, category Article
Eero Väisänen, Pertti Hari, Seppo Kellomäki. (1977). Annual growth level of some plant species as a function of light available for photosynthesis. Silva Fennica vol. 11 no. 4 article id 4980. https://doi.org/10.14214/sf.a14834

A quantitative method for determining the annual growth level of plant species has been presented. In particular, attention was paid to the dependence of the growth level on the amount of light available for photosynthesis. A mathematical model for the dependence of structural matter production on photosynthetic production has been presented for some plant species.

The study is based on the assumption that the total amount of annual net photosynthesis plays a role of primary importance in determining the relationship between photosynthetic production and structural matter production. The basic environmental factors determining the photosynthetic rate are light and temperature, if the water and nutrient supply is adequate. The dependence of photosynthetic rate on light and temperature was determined by monitoring the CO2 uptake rate of natural plant populations between the photosynthetic levels of different plant populations with an infrared gas analyser.

The PDF includes a summary in Finnish.

  • Väisänen, ORCID ID:E-mail:
  • Hari, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
article id 4959, category Article
Irja Lehtonen, Pertti Hari, Seppo Kellomäki, Eero Väisänen. (1977). On control of daily structural matter production in population of Avenella flexuosa (L.) Parl. Silva Fennica vol. 11 no. 1 article id 4959. https://doi.org/10.14214/sf.a14810

In the boreal zone, the environmental control of growth rate, i.e. the rate of irreversible change in shoot dimensions, is assumed to be dominated by temperature. Promnitz (1975) emphasises that in boreal and temperate zones storage of photosynthetic products is an essential part of the growth process, and thus direct interaction between growth rate and radiation is not evident. The aim of the present study was to investigate the control of daily structural matter production in populations of Avenella flexuosa (L.) Drejer. Special attention was paid to the role of temperature and radiation in addition to the self-regulation of the plants themselves.

Temperature and self-regulation were found to explain over 90% of the daily variation of growth rate. Introduction of radiation into the analysis did not increase the explanatory power of the growth model based on temperature and self-regulation.

The PDF includes a summary in Finnish.

  • Lehtonen, ORCID ID:E-mail:
  • Hari, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:
article id 4953, category Article
Seppo Kellomäki, Pertti Hari. (1976). Rate of photosynthesis of some forest mosses as a function of temperature and light intensity and effect of water content of moss cushion on photosynthetic rate. Silva Fennica vol. 10 no. 4 article id 4953. https://doi.org/10.14214/sf.a14799

The photosynthetic rate of Pleurosium schreberi (Willd.), Hylocomnium splendens (Hedw.) and Dicranum undulatum (Sw.) grown in plastic containers was monitored with infrared gas analyser in open air under natural weather conditions. It proved that the photosynthetic rate of wet moss cushions was satisfactorily predicted by temperature and light intensity. In dry moss cushions this kind of model gave too high an estimate for photosynthetic rate. Water requirements of each moss species were found to be moderate, and water content of moss cushions limited photosynthetic rate only under serious water deficiency.

The PDF includes a summary in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Hari, ORCID ID:E-mail:
article id 4905, category Article
Reijo Solantie. (1974). Kesän vesitaseen vaikutus metsä- ja suokasvillisuuteen ja linnustoon sekä lämpöolojen välityksellä maatalouden toimintaedellytyksiin Suomessa. Silva Fennica vol. 8 no. 3 article id 4905. https://doi.org/10.14214/sf.a14749
English title: The influence of water balance in summer on forest and peatland vegetation and bird fauna and through the temperature on agricultural conditions in Finland.

The significance of water budget in June and July for forest and peatland vegetation, and consequent effects on fauna, climate and agriculture has been studied.

In June, the difference between evaporation and precipitation is greater than it is later in the summer. North of the line zero difference of evaporation and precipitation, coinciding with a line of sharp change in forest vegetation, the uppermost part of podsol remains wet throughout the summer. During July, the line of zero difference moves from north to south over the greater part of Finland, run-off being minute and podsol at the driest in this month. This line, indicating the length of the period with evaporation greater than precipitation and causing a sharp change in forest vegetation, in frequency of peatlands, amount of growing stock productive capacity of forests etc. This line is significant also for cultivation: because of the lower evaporation north of this line, night temperature below the freezing point often appear in summer.

The PDF includes a summary in English.

  • Solantie, ORCID ID:E-mail:
article id 4866, category Article
Pertti Hari, Tapio Lehtiniemi. (1972). Lämpötilan ja itämisalustan kosteuden vaikutus kuusen (Picea abies (L.) Karst.) siementen idäntään ja CO2-eritykseen laboratoriossa. Silva Fennica vol. 6 no. 2 article id 4866. https://doi.org/10.14214/sf.a14669
English title: The effect of temperature and moisture on germination and CO2-output of spruce (Picea abies) seeds in a controlled environment.

The study was an attempt to assess, from a theoretical viewpoint and with the techniques of measurement in mind, the usability respiration and cumulative respiration in the observation of the progress of seed germination in Norway spruce (Picea abies (L.) H. Karst.), as well as the influence of air temperature substrate moisture and the stage of physiological development of seeds on respiration. Furthermore, the reserve nutrient consumption and the possible uptake of mineral nutrients were kept under observation during the 9–11 days after seeding.

The results showed that the stage of physiological development of the seeds can be rather well described by the means of cumulative CO2 release. There was a strong interaction in the CO2 release between the moisture of the substrate and the air temperature. It seems to be to great extent due to differences in the rate of development in the early phases of germination. The CO2 release from seeds showed a close correlation with percentage germinated seeds.

The PDF includes a summary in English.

  • Hari, ORCID ID:E-mail:
  • Lehtiniemi, ORCID ID:E-mail:
article id 4784, category Article
Matti Leikola, Pentti Pylkkö. (1969). Verhopuuston tiheyden vaikutus metsikön minimilämpötiloihin hallaöinä. Silva Fennica vol. 3 no. 1 article id 4784. https://doi.org/10.14214/sf.a14570
English title: Influence of stand density on the minimum temperatures during frost nights.

The objective of this investigation was to study the influence of stand density of white birch (Betula pubescens Ehrl.) on the minimum temperatures in the stand during the growing season, and the actual minimum temperatures of the leading shoot of Norway spruce (Picea abies (L.) H. Karst.) seedlings growing in the open. The 40-year-old uniform white birch stand was situated in 142 m above the sea level in Southern Finland. The stand was treated with thinnings of three different densities in 1961.

Air temperature was recorded in four sample plots at heights of 0.1 m, 0.5 m, 1.0 m, 2 m and 4 m. In the stand of moderate density, temperatures were measured at heights of 6.0 m, and in the stand of full density at 6.0 m, 8.0 m and 10.0 m.

The temperature differences between stands of various densities proved to be rather small. Especially the thinnest stand differed very little from the open area. The soil surface has in all cases been warm compared with the higher air layers indicating meadow-fog-type by Geier (1965). On cloudy or windy weather all the temperature profiles in the various stands resembled each other. The difference between the air temperature and temperature of the spruce shoot was greatest at midnight and decreased steadily thereafter.

The problem in using shelter stands for spruce regeneration areas is that optimum shelter stand density is difficult to define. Already a thin shelter stand causes drawbacks to the young seedlings, but in order to be effective enough against early frosts, the shelter stand should be comparatively dense.

The PDF includes a summary in English.

  • Leikola, ORCID ID:E-mail:
  • Pylkkö, ORCID ID:E-mail:
article id 4754, category Article
Matti Leikola. (1967). Havaintoja erään hoidetun männikön tuulisuhteista. Silva Fennica vol. 1 no. 3 article id 4754. https://doi.org/10.14214/sf.a14538
English title: Observations on wind conditions in a managed Scots pine stand.

An explorative study on wind conditions in a well-managed Scots pine (Pinus sylvestris L.) stand was made in Southern Finland. The wind velocity was recorded continually with two cup anomometers from April to August, 1964. The two levels used were 2 m and 9 m. The wind velocity was lower at 2 m than within the canopy at 9 m. The dependence on the absolute wind velocity at 9 metres was logarithmic. The wind velocity did affect the difference between daily minimum temperatures at the two levels; the difference in the maximum temperatures was affected only in May and August.

The PDF includes a summary in English.

  • Leikola, ORCID ID:E-mail:
article id 7506, category Article
Eero Kubin, Lauri Kemppainen. (1994). Effect of soil preparation of boreal spruce forest on air and soil temperature conditions in forest regeneration areas. Acta Forestalia Fennica no. 244 article id 7506. https://doi.org/10.14214/aff.7506

The effect of scarification, ploughing and cross-directional ploughing on temperature conditions in the soil and adjacent air layer have been studied during 11 growth periods by using an unprepared clear-cut area as a control site. The development of seedling stand was followed to determine its shading effect on the soil surface.

Soil preparation decreased the daily temperature amplitude of the air at the height of 10 cm. The maximum temperatures on sunny days were lower in the tilts of the ploughed and in the humps of the cross-directional ploughed sites compared with the unprepared area. Correspondingly, the night temperatures were higher and so the soil preparation reduced the risk of night frost. In the soil at the depth of 5 cm, soil preparation increased daytime temperatures and reduced night temperatures compared with unprepared area. The maximum increase in monthly mean temperatures was almost 5°C, and the daily variation in the surface parts of the tilts and humps increased so that excessively high temperatures for the optimal growth of the root systems were measured from time to time. The temperature also rose at the depths of 50 and 100 cm.

Soil preparation also increased the cumulative temperature sum. The highest sums accumulated during the summer months were recorded at the depth of 5 cm in the humps of cross-directional ploughed area (1,127 dd.) and in the tilts of the ploughed area (1,106 dd.), while the corresponding figure in the unprepared soil was 718 dd. At the height of 10 cm the highest temperature sum was 1,020 dd. in the hump, and 925 dd. in the unprepared area.

The incidence of high temperature amplitudes and frequency of high temperatures at the depth of 5 cm decreased most rapidly in the humps of cross-sectional ploughed area and the ploughing tilts towards the end of the study period. The decrease was attributed principally to the compressing of tilts, the ground vegetation succession and the growth of seedlings. The difference between the prepared and unprepared area did not diminish. The increase in temperature due to soil preparation, thus, lasted at least over 10 years.

  • Kubin, ORCID ID:E-mail:
  • Kemppainen, ORCID ID:E-mail:
article id 7506, category Article
Eero Kubin, Lauri Kemppainen. (1994). Effect of soil preparation of boreal spruce forest on air and soil temperature conditions in forest regeneration areas. Acta Forestalia Fennica no. 244 article id 7506. https://doi.org/10.14214/aff.7506

The effect of scarification, ploughing and cross-directional ploughing on temperature conditions in the soil and adjacent air layer have been studied during 11 growth periods by using an unprepared clear-cut area as a control site. The development of seedling stand was followed to determine its shading effect on the soil surface.

Soil preparation decreased the daily temperature amplitude of the air at the height of 10 cm. The maximum temperatures on sunny days were lower in the tilts of the ploughed and in the humps of the cross-directional ploughed sites compared with the unprepared area. Correspondingly, the night temperatures were higher and so the soil preparation reduced the risk of night frost. In the soil at the depth of 5 cm, soil preparation increased daytime temperatures and reduced night temperatures compared with unprepared area. The maximum increase in monthly mean temperatures was almost 5°C, and the daily variation in the surface parts of the tilts and humps increased so that excessively high temperatures for the optimal growth of the root systems were measured from time to time. The temperature also rose at the depths of 50 and 100 cm.

Soil preparation also increased the cumulative temperature sum. The highest sums accumulated during the summer months were recorded at the depth of 5 cm in the humps of cross-directional ploughed area (1,127 dd.) and in the tilts of the ploughed area (1,106 dd.), while the corresponding figure in the unprepared soil was 718 dd. At the height of 10 cm the highest temperature sum was 1,020 dd. in the hump, and 925 dd. in the unprepared area.

The incidence of high temperature amplitudes and frequency of high temperatures at the depth of 5 cm decreased most rapidly in the humps of cross-sectional ploughed area and the ploughing tilts towards the end of the study period. The decrease was attributed principally to the compressing of tilts, the ground vegetation succession and the growth of seedlings. The difference between the prepared and unprepared area did not diminish. The increase in temperature due to soil preparation, thus, lasted at least over 10 years.

  • Kubin, ORCID ID:E-mail:
  • Kemppainen, ORCID ID:E-mail:
article id 7671, category Article
Eero Kubin, Lauri Kemppainen. (1991). Effect of clearcutting of boreal spruce forest on air and soil temperature conditions. Acta Forestalia Fennica no. 225 article id 7671. https://doi.org/10.14214/aff.7671

The present paper deals with the effects of clearcutting on soil and air temperature and the development of temperature conditions during the 12 growing seasons following clearcutting of a Norway spruce (Picea abies (L.) H. Karst.) stand on a Vaccinium-Myrtillus forest type in Kainuu, northeast Finland. The uncut control site had a growing stock of 140 m3/ha. The temperature measurements were carried out by means of thermographs, Grant measuring devices and minimum and maximum glass thermometers.

Clearcutting had no significant influence on temperatures measures at 2 m above the ground in a meteorological screen and no changes occurred in them during the period studied, while on the ground level and in the adjacent layer of air the daily maxima increased and the daily minima decreased as compared with uncut forest. The greatest difference was over 10°C between the maximum temperatures at 10 cm and almost 8°C between the minimum temperatures. Night frosts were considerably more common at 10 cm above the ground in the clearcut area than in uncut forests.

Temperature differences were smaller in the soil than close to ground level. Day temperatures were 2–3°C higher in the clearcut area than in uncut forests, and differences between night temperatures at this depth were even smaller. Correspondingly, temperatures were 3–5°C higher at depths of 50 cm and 100 cm in the clearcut area during the whole measuring period. The differences between the temperatures in the clearcut area and uncut forests did not diminish to any significant extent during the 12 years despite the stocking of the former area with seedlings.

The PDF includes a summary in Finnish.

  • Kubin, ORCID ID:E-mail:
  • Kemppainen, ORCID ID:E-mail:
article id 7671, category Article
Eero Kubin, Lauri Kemppainen. (1991). Effect of clearcutting of boreal spruce forest on air and soil temperature conditions. Acta Forestalia Fennica no. 225 article id 7671. https://doi.org/10.14214/aff.7671

The present paper deals with the effects of clearcutting on soil and air temperature and the development of temperature conditions during the 12 growing seasons following clearcutting of a Norway spruce (Picea abies (L.) H. Karst.) stand on a Vaccinium-Myrtillus forest type in Kainuu, northeast Finland. The uncut control site had a growing stock of 140 m3/ha. The temperature measurements were carried out by means of thermographs, Grant measuring devices and minimum and maximum glass thermometers.

Clearcutting had no significant influence on temperatures measures at 2 m above the ground in a meteorological screen and no changes occurred in them during the period studied, while on the ground level and in the adjacent layer of air the daily maxima increased and the daily minima decreased as compared with uncut forest. The greatest difference was over 10°C between the maximum temperatures at 10 cm and almost 8°C between the minimum temperatures. Night frosts were considerably more common at 10 cm above the ground in the clearcut area than in uncut forests.

Temperature differences were smaller in the soil than close to ground level. Day temperatures were 2–3°C higher in the clearcut area than in uncut forests, and differences between night temperatures at this depth were even smaller. Correspondingly, temperatures were 3–5°C higher at depths of 50 cm and 100 cm in the clearcut area during the whole measuring period. The differences between the temperatures in the clearcut area and uncut forests did not diminish to any significant extent during the 12 years despite the stocking of the former area with seedlings.

The PDF includes a summary in Finnish.

  • Kubin, ORCID ID:E-mail:
  • Kemppainen, ORCID ID:E-mail:
article id 7633, category Article
Helena Henttonen. (1984). The dependence of annual ring indices on some climatic factors. Acta Forestalia Fennica no. 186 article id 7633. https://doi.org/10.14214/aff.7633

The paper concerns relationship between climatic factors and annual ring indices mainly in Southern Finland. The studied index series were from papers of different authors and from different localities. The monthly mean temperatures and precipitation sums were derived from the measurements of meteorological stations. Effective temperature sums for different periods of the year were calculated from the monthly mean temperatures.

The autocorrelation functions were estimated for each index series. The autocorrelations at lag I were significant except for one series. Altogether the differences in the structures of the index series were noticeable, especially between the Scots pine (Pinus sylvestris L.) index series. The influence of climatic factors on the annual ring index variation was studied using cross correlation analysis, simple distributed lag models and transfer function-noise models.

The decisive factor for the annual ring index variation of Norway spruce (Picea abies (L.) H. Karst.) appears to be the effective temperature sum of the growing season. Warm periods during latter parts of previous summer had a negative effect on indices. For the variation of the Scots pine indices the most important climatic factors were the effective temperature sum of the latter part of the growing season and, especially on the arid sites, the precipitation sum during May-July.

The PDF includes a summary in Finnish.

  • Henttonen, ORCID ID:E-mail:
article id 7633, category Article
Helena Henttonen. (1984). The dependence of annual ring indices on some climatic factors. Acta Forestalia Fennica no. 186 article id 7633. https://doi.org/10.14214/aff.7633

The paper concerns relationship between climatic factors and annual ring indices mainly in Southern Finland. The studied index series were from papers of different authors and from different localities. The monthly mean temperatures and precipitation sums were derived from the measurements of meteorological stations. Effective temperature sums for different periods of the year were calculated from the monthly mean temperatures.

The autocorrelation functions were estimated for each index series. The autocorrelations at lag I were significant except for one series. Altogether the differences in the structures of the index series were noticeable, especially between the Scots pine (Pinus sylvestris L.) index series. The influence of climatic factors on the annual ring index variation was studied using cross correlation analysis, simple distributed lag models and transfer function-noise models.

The decisive factor for the annual ring index variation of Norway spruce (Picea abies (L.) H. Karst.) appears to be the effective temperature sum of the growing season. Warm periods during latter parts of previous summer had a negative effect on indices. For the variation of the Scots pine indices the most important climatic factors were the effective temperature sum of the latter part of the growing season and, especially on the arid sites, the precipitation sum during May-July.

The PDF includes a summary in Finnish.

  • Henttonen, ORCID ID:E-mail:
article id 7616, category Article
Min-Sup Chung. (1981). Flowering characteristics of Pinus sylvestris L. with special emphasis on the reproductive adaptation to local temperature factor. Acta Forestalia Fennica no. 169 article id 7616. https://doi.org/10.14214/aff.7616

Flowering time and characteristics of cones and seed development of Scots pine (Pinus sylvestris L.) plus tree clones originating from various parts of Finland and planted (grafts) in Southern Finland (61° 48’ N, 29° 19’ E) were studied during 1976-1978.

The flowering time (in terms of period unit (p.u.) sums for flowering) of the Scots pine plus tree clones showed characteristics specific to each population and the characteristics appear mainly adapted to the local temperature factor within Finland. Generally, the development of floral organs, cones and seed in the spring and summer seasons also showed a temperature dependence in that the reproductive organs are developed rapidly and/or favourably under higher temperature conditions within its optimum range.

In this respect, establishment of northern Scots pine seed orchards in Central or Southern Finland or an optimum flowering, and a favourable seed development with an optimum physiological reproductive isolation from surrounding Scots pine populations can be justified. Problem arising from the north-south transfer of seed orchards and the significance of trees’ growth rhythm are discussed in connection with tree improvement.

The PDF includes a summary in Finnish.

  • Chung, ORCID ID:E-mail:
article id 7596, category Article
Olavi Luukkanen. (1978). Investigations on factors affecting net photosynthesis in trees : gas exchanges in clones of Picea abies (L.) Karst. Acta Forestalia Fennica no. 162 article id 7596. https://doi.org/10.14214/aff.7596

The net photosynthetic rate per unit of foliage was studied in two-year old cuttings of Norway spruce (Picea abies (L.) H. Karst.), representing four clones, at varying temperature and soil moisture. The CO2 compensation point (Γ), photorespiration, dark respiration, and water balance were also investigated. All these characteristics indicated differences among the clones. A correlation between CO2 exchange and transpiration suggested that stomatal control determined at least a part of this variation during a favourable water balance. An inverse relationship existed between Γ and net photosynthetic rate, and the same curvilinear model explained this variation in unstressed as well as stressed plants at a given temperature. An increase in Γ seems to be a normal result of water stress, particularly at high temperature, indicating an increase in mesophyll resistance to CO2 diffusion. This result was in agreement with calculated values of mesophyll resistance. It also supported our earlier conclusions about the significance of mesophyll resistance during water stress.

  • Luukkanen, ORCID ID:E-mail:
article id 7584, category Article
Leo Heikurainen, Jukka Laine. (1976). Lannoituksen, kuivatuksen ja lämpöolojen vaikutus istutus- ja luonnontaimistojen kehitykseen rämeillä. Acta Forestalia Fennica no. 150 article id 7584. https://doi.org/10.14214/aff.7584
English title: Effect of fertilization, drainage and temperature on the development of planted and natural seedlings on pine swamps.

The paper presents some preliminary results of a 10-year-old study the purpose of which is to determine the effect of simultaneous variations in the intensity of drainage and fertilization on the development of planted and natural seedlings on peatlands under various climatic conditions. The development of the Scots pine (Pinus sylvestris L.) seedlings appeared to be better the more intensive the degree of drainage and fertilization used. The increase in the temperature sum had a positive effect on the development of pine seedlings and decreased the mortality rate.

The best growth result was obtained with a 10 m ditch spacing and strong fertilization. As it is difficult to decrease the 10 m ditch spacing for cost reasons, it can be concluded that on such oligotrophic peatlands as were used in this experiment, only an average growth level in the seedling stands can be reached even with the most efficient forest improvement measures. Broadcast fertilization used in the experiment, at least in large doses, increases seedling mortality, as well as the coverage of the ground vegetation, particularly that of cottongrass and fireweed, and also the shrub height, thus increasing competition. It cannot be recommended for afforestation, and today spot fertilization is used. According to this experiment natural seedlings seem once they have recovered after the first years, to grow better than the planted seedlings. This was true especially in the north and in areas, where drainage was not efficient. The height and height growth of the seedlings were to a large extent dependent on the temperature sum.

The PDF includes a summary in English.

  • Heikurainen, ORCID ID:E-mail:
  • Laine, ORCID ID:E-mail:
article id 4714, category Article
B. L. Dzerdzeevskii. (1963). Study of the heat balance of the forest. Silva Fennica no. 113 article id 4714. https://doi.org/10.14214/sf.a14272
  • Dzerdzeevskii, ORCID ID:E-mail:
article id 7541, category Article
Tauno Kallio. (1970). Aerial distribution of the root-rot fungus Fomes annosus (Fr.) Cooke in Finland. Acta Forestalia Fennica no. 107 article id 7541. https://doi.org/10.14214/aff.7541

An investigation into the aerial distribution of Fomes annosus (now Heterbasidion annosum) in Finland was carried out. Prevalence of the fungus in the air was estimated from cultural counts of mycelia produced by diaspores which had fallen onto spruce discs and agar plates. The influence of climate on deposition of diaspores was determined from weather recordings.

For the main study, F. annosus diaspores collected from spruce stands in Helsinki, Anjala and Jokioinen were recorded at weekly or fortnightly intervals throughout 1968. Diaspores fell during the 24-hour periods almost continuously at all three observation sites from April to November, but the deposition was most frequent from late May to the end of October. The amounts of deposition varied greatly with the observation sites, seasons of the year, and time of the day. The fall was heaviest at Anjala and slightest at Jokioinen.

Throughout the season of deposition, more diaspores were trapped on all observation sites at night than during the day. A significant positive correlation was found between the fall of F. annosus diaspores and the air temperature. Diaspores of F. annosus were found in the forest on needles and leaves, and underneath the humus layer in mineral soil. The fall of diaspores decreased as the distance from sporophores increased.

The aerial distribution of two antagonists to F. annosus, viz. Peniophora gigantea and Trichoderma viride, was also studied. It was found that the diaspores of the former fell mainly during the same seasons as those of F. annosus.

  • Kallio, ORCID ID:E-mail:
article id 7610, category Article
Matti Leikola. (1969). The influence of environmental factors on the diameter growth of forest trees : Auxanometric study. Acta Forestalia Fennica no. 92 article id 7610. https://doi.org/10.14214/aff.7610

The influence of various environmental factors on the diameter growth of trees has been studied based on data collected by following daily increment of trees and various environmental factors during the growing season in 1964–1967. The field work was carried out in two experimental stands, a Scots pine (Pinus sylvestris L.) stand and a mixed stands growing birch (Betula sp.), Norway spruce (Picea abies (L.) H. Karst.) and Scots pine, in Southern Finland.

The results show that the temperature sums preceding the beginning of diameter growth were of the same magnitude in the years studied, which indicates dependence in the relationship. Formation of new xylem cells took place in the pine stem ca. every third day when the diameter growth was most active. No summer growth inhibition was detected in diameter growth.

None of the cumulative temperature sums tried determined the time of cessation of diameter growth. In several cases, positive correlation was found between the length of the growing season and the width of the annual ring formed. When studying the relationships between the diameter increment and the environmental factors, it was found that diameter increment was totally masked in the records by the hydrostatic changes in the stem. Relationships between the diameter increment and the environmental factors of the second day preceding growth were found to be poor. In studying the deviations of the recorded daily increments from the regression surface, no clear general trend was seen for pine and spruce, but clear diminishing trend toward the end og the growing season could be seen for birch in 1967.

  • Leikola, ORCID ID:E-mail:
article id 7610, category Article
Matti Leikola. (1969). The influence of environmental factors on the diameter growth of forest trees : Auxanometric study. Acta Forestalia Fennica no. 92 article id 7610. https://doi.org/10.14214/aff.7610

The influence of various environmental factors on the diameter growth of trees has been studied based on data collected by following daily increment of trees and various environmental factors during the growing season in 1964–1967. The field work was carried out in two experimental stands, a Scots pine (Pinus sylvestris L.) stand and a mixed stands growing birch (Betula sp.), Norway spruce (Picea abies (L.) H. Karst.) and Scots pine, in Southern Finland.

The results show that the temperature sums preceding the beginning of diameter growth were of the same magnitude in the years studied, which indicates dependence in the relationship. Formation of new xylem cells took place in the pine stem ca. every third day when the diameter growth was most active. No summer growth inhibition was detected in diameter growth.

None of the cumulative temperature sums tried determined the time of cessation of diameter growth. In several cases, positive correlation was found between the length of the growing season and the width of the annual ring formed. When studying the relationships between the diameter increment and the environmental factors, it was found that diameter increment was totally masked in the records by the hydrostatic changes in the stem. Relationships between the diameter increment and the environmental factors of the second day preceding growth were found to be poor. In studying the deviations of the recorded daily increments from the regression surface, no clear general trend was seen for pine and spruce, but clear diminishing trend toward the end og the growing season could be seen for birch in 1967.

  • Leikola, ORCID ID:E-mail:

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