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Silva Fennica 1926-1997
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Articles containing the keyword 'increment'.

Category: Research article

article id 1760, category Research article
Marek Fajstavr, Kyriaki Giagli, Hanuš Vavrčík, Vladimír Gryc, Josef Urban. (2017). The effect of stem girdling on xylem and phloem formation in Scots pine. Silva Fennica vol. 51 no. 4 article id 1760. https://doi.org/10.14214/sf.1760
Highlights: Stem girdling ceased the cambial activity, below the girdled area, immediately after the removal of the bark strip; Pinus sylvestris survived for up to two years after stem girdling; The girdled trees formed phloem cells above the girdled area but failed to form latewood cells in the next growing season.

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

  • Fajstavr, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: fajstavr.marek@seznam.cz (email)
  • Giagli, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: kyriaki.giagli@mendelu.cz
  • Vavrčík, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: vavrcik@mendelu.cz
  • Gryc, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: gryc@mendelu.cz
  • Urban, Department of Forest Botany, Dendrology and Geobiocenology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic;  Siberian Federal University, Svobodnyj Prospect 79, Krasnoyarsk, 660041 Krasnoyarsk, Russia ORCID ID:E-mail: josef.urban@email.cz
article id 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 1262, category Research article
Āris Jansons, Roberts Matisons, Māra Zadiņa, Linards Sisenis, Jānis Jansons. (2015). The effect of climatic factors on height increment of Scots pine in sites differing by continentality in Latvia. Silva Fennica vol. 49 no. 3 article id 1262. https://doi.org/10.14214/sf.1262
Highlights: Height increment-climate relationships of Scots pine were assessed using dendrochronological techniques; Annual height increment was significantly affected by climatic factors; In western Latvia, temperature in preceding summer mainly affected height increment; In eastern Latvia height increment was affected by previous autumn temperature; During the 20th century, the effect of climatic factors has altered likely dues to climate change.
Height growth of trees is a crucial parameter that influences the composition and productivity of forest stands and quality of timber; however, the relationships between annual height increment (HI) and climatic factors have been poorly studied. In this study, the effect of monthly mean temperature and precipitation sums on the HI of Scots pine in two sites in Latvia have been determined using dendrochronological techniques. Correlation and response function analyses were conducted for entire chronologies of HI and for 50-year intervals within them. Climatic factors significantly affected the HI of Scots pine; however, not only did the suite of significant factors differ between the sites, but the influence of these factors changed during the 20th century. In the site in western Latvia where climate is milder, temperature in the preceding summer was the main climatic determinant of HI. The effect of temperature in the dormant period and spring was significant during the first part of the 20th century, while the effect of temperature in the previous September and November has become significant since the second half of the 20th century. In the site in eastern Latvia where summers are hotter, HI has been affected by both temperature and water deficit related factors in the summer. However, since the later part of the 20th century, the effect of temperature in the previous October has intensified and become the main climatic determinant of HI.
  • Jansons,  LSFRI “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: aris.jansons@silava.lv
  • Matisons,  LSFRI “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: robism@inbox.lv (email)
  • Zadiņa,  LSFRI “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: mara.zadina@silava.lv
  • Sisenis, LUA Forestry Faculty, Akadēmijas str. 11, Jelgava, Latvia ORCID ID:E-mail: linards.sisenis@llu.lv
  • Jansons, Forest Competence Centre, Dzērbenes str. 27, Riga, Latvia, LV1006 ORCID ID:E-mail: janis.jansons@silava.lv
article id 54, category Research article
Urban Nilsson, Björn Elfving, Kjell Karlsson. (2012). Productivity of Norway spruce compared to Scots pine in the interior of northern Sweden. Silva Fennica vol. 46 no. 2 article id 54. https://doi.org/10.14214/sf.54
Productivity of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) was studied in 12 paired plots in the interior of northern Sweden. Stands were established between 1928 and 1959; yield plots were established between 1974 and 1983 during pre-commercial thinning of the stands. Gross stem-wood production was significantly higher for Scots pine than for Norway spruce, stem-wood production by Norway spruce being 29.4% that of Scots pine. The site index for Norway spruce was lower than for Scots pine at all sites except one; the average difference in site index was 4.8 m. The simulated maximum mean annual increment (MAImax) during the rotation was 19% higher than the MAImax estimated with the site index for Scots pine, whereas simulated MAImax and MAImax estimated from the site index was about the same for Norway spruce. The simulations also indicated that MAI peaked about 50 years later for Norway spruce than for Scots pine. More small trees were included in the diameter distribution of Norway spruce than of Scots pine resulting in a lower stem-wood volume for Norway spruce when stands with the same dominant height were compared. This study shows that the difference in growth and rotation length between Scots pine and Norway spruce has implications when choosing which species to grow in the interior of northern Sweden.
  • Nilsson, Swedish University of Agricultural Sciences (SLU), Southern Swedish Forest Research Centre, Alnarp, Sweden ORCID ID:E-mail: urban.nilsson@slu.se (email)
  • Elfving, SLU, Forest Ecology and Management, Umeå, Sweden ORCID ID:E-mail:
  • Karlsson, SLU, Unit of Field Based Research, Asa, Sweden ORCID ID:E-mail:
article id 54, category Research article
Urban Nilsson, Björn Elfving, Kjell Karlsson. (2012). Productivity of Norway spruce compared to Scots pine in the interior of northern Sweden. Silva Fennica vol. 46 no. 2 article id 54. https://doi.org/10.14214/sf.54
Productivity of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) was studied in 12 paired plots in the interior of northern Sweden. Stands were established between 1928 and 1959; yield plots were established between 1974 and 1983 during pre-commercial thinning of the stands. Gross stem-wood production was significantly higher for Scots pine than for Norway spruce, stem-wood production by Norway spruce being 29.4% that of Scots pine. The site index for Norway spruce was lower than for Scots pine at all sites except one; the average difference in site index was 4.8 m. The simulated maximum mean annual increment (MAImax) during the rotation was 19% higher than the MAImax estimated with the site index for Scots pine, whereas simulated MAImax and MAImax estimated from the site index was about the same for Norway spruce. The simulations also indicated that MAI peaked about 50 years later for Norway spruce than for Scots pine. More small trees were included in the diameter distribution of Norway spruce than of Scots pine resulting in a lower stem-wood volume for Norway spruce when stands with the same dominant height were compared. This study shows that the difference in growth and rotation length between Scots pine and Norway spruce has implications when choosing which species to grow in the interior of northern Sweden.
  • Nilsson, Swedish University of Agricultural Sciences (SLU), Southern Swedish Forest Research Centre, Alnarp, Sweden ORCID ID:E-mail: urban.nilsson@slu.se (email)
  • Elfving, SLU, Forest Ecology and Management, Umeå, Sweden ORCID ID:E-mail:
  • Karlsson, SLU, Unit of Field Based Research, Asa, Sweden ORCID ID:E-mail:
article id 394, category Research article
Rafael Calama, Gregorio Montero. (2005). Multilevel linear mixed model for tree diameter increment in stone pine (Pinus pinea): a calibrating approach. Silva Fennica vol. 39 no. 1 article id 394. https://doi.org/10.14214/sf.394
Diameter increment for stone pine (Pinus pinea L.) is described using a multilevel linear mixed model, where stochastic variability is broken down among period, plot, tree and within-tree components. Covariates acting at tree and stand level, as breast height diameter, density, dominant height or site index are included in the model as fixed effects in order to explain residual random variability. The effect of competition on diameter increment is expressed by including distance independent competition indices. The entrance of regional effects within the model is tested to determine whether a single model is sufficient to explain stone pine diameter increment in Spain, or if, on the contrary, regional models are needed. Diameter increment model can be calibrated by predicting random components using data from past growth measurements taken in a complementary sample of trees. Calibration is carried out by using the best linear unbiased predictor (BLUP) theory. Both the fixed effects model and the calibrated model mean a substantial improvement when compared with the classical approach, widely used in forest management, of assuming constancy in diameter increment for a short projection period.
  • Calama, CIFOR-INIA, Grupo Selvicultura Mediterranea, Apdo. 8111, 28080 Madrid, Spain ORCID ID:E-mail: rcalama@inia.es (email)
  • Montero, CIFOR-INIA, Grupo Selvicultura Mediterranea, Apdo. 8111, 28080 Madrid, Spain ORCID ID:E-mail:

Category: Review article

article id 1660, category Review article
Lars Rytter, Morten Ingerslev, Antti Kilpeläinen, Piritta Torssonen, Dagnija Lazdina, Magnus Löf, Palle Madsen, Peeter Muiste, Lars-Göran Stener. (2016). Increased forest biomass production in the Nordic and Baltic countries – a review on current and future opportunities. Silva Fennica vol. 50 no. 5 article id 1660. https://doi.org/10.14214/sf.1660
Highlights: Annual growth is 287 million m3 in the forests of the Nordic and Baltic countries; Growth can be increased by new tree species, tree breeding, high-productive management systems, fertilization and afforestation of abandoned agricultural land; We predict a forest growth increment of 50–100% is possible at the stand scale; 65% of annual growth is harvested today.

The Nordic and Baltic countries are in the frontline of replacing fossil fuel with renewables. An important question is how forest management of the productive parts of this region can support a sustainable development of our societies in reaching low or carbon neutral conditions by 2050. This may involve a 70% increased consumption of biomass and waste to meet the goals. The present review concludes that a 50–100% increase of forest growth at the stand scale, relative to today’s common level of forest productivity, is a realistic estimate within a stand rotation (~70 years). Change of tree species, including the use of non-native species, tree breeding, introduction of high-productive systems with the opportunity to use nurse crops, fertilization and afforestation are powerful elements in an implementation and utilization of the potential. The productive forests of the Nordic and Baltic countries cover in total 63 million hectares, which corresponds to an average 51% land cover. The annual growth is 287 million m3 and the annual average harvest is 189 million m3 (65% of the growth). A short-term increase of wood-based bioenergy by utilizing more of the growth is estimated to be between 236 and 416 TWh depending on legislative and operational restrictions. Balanced priorities of forest functions and management aims such as nature conservation, biodiversity, recreation, game management, ground water protection etc. all need consideration. We believe that these aims may be combined at the landscape level in ways that do not conflict with the goals of reaching higher forest productivity and biomass production.

  • Rytter, The Forestry Research Institute of Sweden (Skogforsk), Ekebo 2250, SE-26890 Svalöv, Sweden ORCID ID:E-mail: lars.rytter@skogforsk.se (email)
  • Ingerslev, Copenhagen University, Department of Geosciences and Natural Resource Management, Rolighedsvej 23, DK-1958, Frederiksberg C, Denmark ORCID ID:E-mail: moi@ign.ku.dk
  • Kilpeläinen, Finnish Environment Institute, Joensuu Office, P.O. Box 111, FI-80101 Joensuu, Finland; University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: antti.kilpelainen@ymparisto.fi
  • Torssonen, University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: Piritta.Torssonen@uef.fi
  • Lazdina, Latvian State Forest Research Institute “Silava”, 111 Riga str, Salaspils, LV 2169 Latvia ORCID ID:E-mail: Dagnija.Lazdina@silava.lv
  • Löf, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, Box 49 SE-230 53 Alnarp, Sweden ORCID ID:E-mail: magnus.lof@slu.se
  • Madsen, Copenhagen University, Department of Geosciences and Natural Resource Management, Rolighedsvej 23, DK-1958, Frederiksberg C, Denmark ORCID ID:E-mail: pam@ign.ku.dk
  • Muiste, Estonian University of Life Sciences, Institute of Forestry and Rural Engineering, Dept. Forest Industry, Kreutzwaldi 5, Tartu 51014, Estonia ORCID ID:E-mail: Peeter.Muiste@emu.ee
  • Stener, The Forestry Research Institute of Sweden (Skogforsk), Ekebo 2250, SE-26890 Svalöv, Sweden ORCID ID:E-mail: Lars-Goran.Stener@skogforsk.se

Category: Research note

article id 1255, category Research note
Āris Jansons, Roberts Matisons, Līga Puriņa, Una Neimane, Jānis Jansons. (2015). Relationships between climatic variables and tree-ring width of European beech and European larch growing outside of their natural distribution area. Silva Fennica vol. 49 no. 1 article id 1255. https://doi.org/10.14214/sf.1255
Highlights: In western Latvia, variation of tree-ring width of European beech and European larch within stands was similar; Dry summers and cold winters caused common event years in tree-rings; Moisture availability at the end of summer was apparently the main limiting factor for tree-ring width; Winter and spring temperature did not have significant and lasting effect on variation of tree-ring width.
Relationships between climatic variables and tree-ring width (TRW) of dominant European larch (Larix decidua Mill.) and European beech (Fagus sylvatica L.) trees growing outside of their natural distribution area in western Latvia were studied. Chronologies of TRW, which covered the periods 1949–2012 and 1911–2012, were produced for beech and larch, respectively. Common signatures in TRW between both species were observed, but their amplitude differed. Correlation analysis showed that variation of TRW of both species was affected by drought related climatic variables. Tree-ring width of beech was affected by temperature in the previous July and August and the effect of spring and autumn temperature was observed. Since the 1980s, the effect of July precipitation has become significant. Summer precipitation was significant for larch in the mid-part of the previous century; however, temperature in the previous September has become a limiting factor since 1970s. The limiting effect of winter and spring temperature apparently lost its significance around the 1950s.
  • Jansons, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: aris.jansons@silava.lv
  • Matisons, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: robism@inbox.lv (email)
  • Puriņa, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: liga.purina@silava.lv
  • Neimane, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: una.neimane@silava.lv
  • Jansons, Forest Competence Centre, Dzerbenes str. 27, Riga, Latvia, LV1006 ORCID ID:E-mail: janis.jansons@mnkc.lv

Category: Article

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

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

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

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

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

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

  • Heikurainen, ORCID ID:E-mail:
  • Seppälä, ORCID ID:E-mail:
article id 7153, category Article
Kullervo Kuusela. (1964). Increment-drain forecast for a large forest area. Acta Forestalia Fennica vol. 77 no. 5 article id 7153. https://doi.org/10.14214/aff.7153

The most important fact to consider in attempting to develop an increment forecast method is the great dependency of the increment on the growing stock volume. Although the site (soil and climate) produces the increment and volume, there would be no increment without the volume as an increment capital. The cutting possibilities are still more dependent on the existing growing stock. Thus, the primary characteristics in management planning is the growing stock volume. The methodological starting point in this paper is that the increment is considered dependent variable which can be explained by other growing stock characteristics. The basis of the analysis and the primary object of this investigation is the increment percentage. Using available and measured sample plots the increment percentage will be analysed as a dependent variable by other growing stock characteristics.

The main emphasis will be the methods which can be used in connection with the interacting increment and drain. An increment-drain forecast should give at least approximately the allowable cut in timber products. Thus, it will be attempted to find the stock characteristics determining the amounts of timber products.

The article introduces the theory and basic concepts of the increment-drain process, increment functions and basal area – height method, and discusses estimation of timber products in increment-drain forecast, fluctuations of the increment, mortality in connection with the increment-drain forecast, and the scheme of cutting budget for desirable growing stock. Finally, it gives some proposals, based on the investigation, for preparing an increment-drain forecast for a large forest area.

The PDF includes a summary in Finnish.

  • Kuusela, ORCID ID:E-mail:
article id 7153, category Article
Kullervo Kuusela. (1964). Increment-drain forecast for a large forest area. Acta Forestalia Fennica vol. 77 no. 5 article id 7153. https://doi.org/10.14214/aff.7153

The most important fact to consider in attempting to develop an increment forecast method is the great dependency of the increment on the growing stock volume. Although the site (soil and climate) produces the increment and volume, there would be no increment without the volume as an increment capital. The cutting possibilities are still more dependent on the existing growing stock. Thus, the primary characteristics in management planning is the growing stock volume. The methodological starting point in this paper is that the increment is considered dependent variable which can be explained by other growing stock characteristics. The basis of the analysis and the primary object of this investigation is the increment percentage. Using available and measured sample plots the increment percentage will be analysed as a dependent variable by other growing stock characteristics.

The main emphasis will be the methods which can be used in connection with the interacting increment and drain. An increment-drain forecast should give at least approximately the allowable cut in timber products. Thus, it will be attempted to find the stock characteristics determining the amounts of timber products.

The article introduces the theory and basic concepts of the increment-drain process, increment functions and basal area – height method, and discusses estimation of timber products in increment-drain forecast, fluctuations of the increment, mortality in connection with the increment-drain forecast, and the scheme of cutting budget for desirable growing stock. Finally, it gives some proposals, based on the investigation, for preparing an increment-drain forecast for a large forest area.

The PDF includes a summary in Finnish.

  • Kuusela, ORCID ID:E-mail:
article id 7153, category Article
Kullervo Kuusela. (1964). Increment-drain forecast for a large forest area. Acta Forestalia Fennica vol. 77 no. 5 article id 7153. https://doi.org/10.14214/aff.7153

The most important fact to consider in attempting to develop an increment forecast method is the great dependency of the increment on the growing stock volume. Although the site (soil and climate) produces the increment and volume, there would be no increment without the volume as an increment capital. The cutting possibilities are still more dependent on the existing growing stock. Thus, the primary characteristics in management planning is the growing stock volume. The methodological starting point in this paper is that the increment is considered dependent variable which can be explained by other growing stock characteristics. The basis of the analysis and the primary object of this investigation is the increment percentage. Using available and measured sample plots the increment percentage will be analysed as a dependent variable by other growing stock characteristics.

The main emphasis will be the methods which can be used in connection with the interacting increment and drain. An increment-drain forecast should give at least approximately the allowable cut in timber products. Thus, it will be attempted to find the stock characteristics determining the amounts of timber products.

The article introduces the theory and basic concepts of the increment-drain process, increment functions and basal area – height method, and discusses estimation of timber products in increment-drain forecast, fluctuations of the increment, mortality in connection with the increment-drain forecast, and the scheme of cutting budget for desirable growing stock. Finally, it gives some proposals, based on the investigation, for preparing an increment-drain forecast for a large forest area.

The PDF includes a summary in Finnish.

  • Kuusela, ORCID ID:E-mail:
article id 7138, category Article
Kullervo Kuusela, Pekka Kilkki. (1963). Multiple regression of increment percentage on other characteristics in Scots pine stands. Acta Forestalia Fennica vol. 75 no. 4 article id 7138. https://doi.org/10.14214/aff.7138

The objective of this study has been to discover some of the basic principles on which an increment for a large forest area might be forecast. Because the stands in a large forest area vary considerably in density and are subject to different kinds of treatment, the main interest falls on the stand characteristics which determine the increment percentage in such forest conditions as these. The material used in the study has been published earlier, it consisted of sample plots of Scots pine (Pinus sylvestris L.) stands (Nyyssönen 1954).

Increment functions are of great importance in the increment forecast for cutting budget. Because 60-80% of the variation in the increment percentage can be explained by stand characteristics in circumstances where the age of the stand is 40-130 years and the volume vary with a coefficient of variation 0.6-0.7, regression equations for increment percentage may be based on a number of sample plots smaller than in a growing stock inventory in the same conditions. It is possible to get accurate results with relatively small number of sample plots. Furthermore, the smaller amount of increment sample plots makes it possible to develop measurement techniques.

The increment functions enable study of increment as a biological process. However, conclusions about biological process on the basis of regression equations should be made with caution. Still, regression analysis is a powerful tool in yield studies.

The PDF includes a summary in Finnish.

  • Kuusela, ORCID ID:E-mail:
  • Kilkki, ORCID ID:E-mail:
article id 7117, category Article
Leo Heikurainen. (1961). Metsäojituksen vaikutuksesta puuston kasvuun ja poistumaan hakkuusuunnitteiden laskemista varten. Acta Forestalia Fennica vol. 71 no. 8 article id 7117. https://doi.org/10.14214/aff.7117
English title: The influence of forest drainage on growth and removal in Finland. For estimations of allowable cut.

The Finnish forest industry is undergoing a vast expansion, which has raised questions of forest balance. This paper studies the possibilities to increase the amount available timber by means of forest drainage. About third of the Finnish land area is peatlands. The calculations of the investigation are based on Forestry Board districts. Based on earlier studies, there is estimated to be 3,042,000 ha of true drainable swamps, 973,000 ha of poor swamps, 1,381,000 ha of uplands in need of drainage, and 1,205,000 ha of drained peatlands. Therefore, the area of drainable and drained lands totals 6,6 million ha, and requirement of forest drainage 5,4 million ha. The drainage hardly reaches this extent, however. It can be assumed that part of the poor swamps is uneconomical to drain. In addition, a half of the paludified forest land will probably not be drained. Thus, it can be estimated that the area to be drained in the future is about 5 million ha. It seems possible that this area could be drained within about 50 years with the present draining capacity.

Draining of all objects of forests would increase the annual increment of our forests, in time, by about 10.5 million m3. This would signify an increase of 23% compared to the present growth of the forests. The increase in the growth consists mainly of softwood: 16% is birch, and the remaining 84% almost equally of Scots pine and Norway spruce. The increase of growth is relatively slow. Depending on the rate of the drainage program, the mean increase of growth will be reached in about 25–35 years. The increase in removal indicated by the increase in the mean increment will be reached in only 50–60 years.

The PDF includes a summary in English.

  • Heikurainen, ORCID ID:E-mail:
article id 7117, category Article
Leo Heikurainen. (1961). Metsäojituksen vaikutuksesta puuston kasvuun ja poistumaan hakkuusuunnitteiden laskemista varten. Acta Forestalia Fennica vol. 71 no. 8 article id 7117. https://doi.org/10.14214/aff.7117
English title: The influence of forest drainage on growth and removal in Finland. For estimations of allowable cut.

The Finnish forest industry is undergoing a vast expansion, which has raised questions of forest balance. This paper studies the possibilities to increase the amount available timber by means of forest drainage. About third of the Finnish land area is peatlands. The calculations of the investigation are based on Forestry Board districts. Based on earlier studies, there is estimated to be 3,042,000 ha of true drainable swamps, 973,000 ha of poor swamps, 1,381,000 ha of uplands in need of drainage, and 1,205,000 ha of drained peatlands. Therefore, the area of drainable and drained lands totals 6,6 million ha, and requirement of forest drainage 5,4 million ha. The drainage hardly reaches this extent, however. It can be assumed that part of the poor swamps is uneconomical to drain. In addition, a half of the paludified forest land will probably not be drained. Thus, it can be estimated that the area to be drained in the future is about 5 million ha. It seems possible that this area could be drained within about 50 years with the present draining capacity.

Draining of all objects of forests would increase the annual increment of our forests, in time, by about 10.5 million m3. This would signify an increase of 23% compared to the present growth of the forests. The increase in the growth consists mainly of softwood: 16% is birch, and the remaining 84% almost equally of Scots pine and Norway spruce. The increase of growth is relatively slow. Depending on the rate of the drainage program, the mean increase of growth will be reached in about 25–35 years. The increase in removal indicated by the increase in the mean increment will be reached in only 50–60 years.

The PDF includes a summary in English.

  • Heikurainen, ORCID ID:E-mail:
article id 7115, category Article
Kullervo Kuusela. (1960). Volume and increment calculation of a sample plot determined with the relascope. Acta Forestalia Fennica vol. 71 no. 6 article id 7115. https://doi.org/10.14214/aff.7115

The relascope method, introduced by Bitterlich, has been mostly used in estimating the basal area of tree stands or growing stock. Volume estimation requires, in addition, mean height and form. The purpose of this study is to work out a method for calculating the volume, bark and increment of the stand from the measurements of sample trees taken on a plot determined with the relascope. All trees of the same diameter have their own plot size and the stand characteristics are the sum of all tree characteristics multiplied by a blow-up factor which is a function of the diameter.

Accurate determination of a sample plot with the relascope requires checking the boundary trees with a tape. In an average forest there are 10 to 20 unit trees on each plot if the opening of the relascope is 2 cm. Because all trees of equal diameter to be tallied on a sample plot represent an equal share of the total basal area, the number of trees to be tallied is very economical from the stand point of volume estimation. Objective selection of the sample trees can easily be done. The unit volume per hectare represented by each tallied tree, or by each sample tree, is directly proportional to the tree height. Thus, the estimates of the stock characteristics can be calculated as arithmetic means from the sample tree characteristics. The calculation procedure which gives the ordinary stock table, volume, bark and increment is also easily carried out with punched cards.

The PDF includes a summary in Finnish.

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

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

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

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

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

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

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

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

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

The PDF includes a summary in English.

  • Kuusela, ORCID ID:E-mail:
article id 7481, category Article
Kullervo Kuusela. (1959). Kasvuennusteen suorittaminen hakkuulaskelman yhteydessä. Acta Forestalia Fennica vol. 67 no. 7 article id 7481. https://doi.org/10.14214/aff.7481
English title: Increment forecast in connection with cutting budget.

The purpose of this study was to clarify increment forecast methods in connection with the cutting budget. The emphasis is laid on the Finnish increment per cent methods. A tentative attempt is made to carry out a passage calculation. Increment forecasts are accomplished for diameter class distribution of a 60 years old Scots pine (Pinus sylvestris L.) stand. The increment data for the growing stock are taken from the domestic increment calculating tables.

When comparing the results of the two methods, the increment values are expressed in rabatt per cent in which the forecasted annual increment is in proportion to the initial value of the growing stock. It will be emphasized that the weak point in the domestic budgets is in the relation between the increment of the developable stock and the increment of the exploitable stock. Almost all the Finnish increment data are from the developable trees and the estimates of the increment of the exploitable trees have not been on sufficient facts.

The PDF includes a summary in English.

  • Kuusela, ORCID ID:E-mail:
article id 7408, category Article
Kullervo Kuusela. (1953). Zur Theorie der forstlichen Zuwachsberechnung auf Grund der periodischen Messung. Acta Forestalia Fennica vol. 60 no. 1 article id 7408. https://doi.org/10.14214/aff.7408
English title: On theory of forest increment calculation based on periodic measurements.

The article presents the background of increment calculations and periodic measurements of forests, as well the historical development of increment calculations in North-America, Middle-Europe, Scandinavia and Finland. The measurements and calculations are presented for individual trees, for a forest stand and for the total resource of a normal forest stand.   

The practice of increment calculations has still some problems regarding the measurements of standing and harvested trees. The article discusses some ways to overcome the problems. 

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

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

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

The PDF includes a summary in German.

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

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

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

The PDF includes a summary in German.

  • Heikkilä, ORCID ID:E-mail:
article id 5508, category Article
Kullervo Kuusela. (1993). Trends of European forest resources on the basis of the FAO/ECE Timber Committee resource assessments. Silva Fennica vol. 27 no. 2 article id 5508. https://doi.org/10.14214/sf.a15669

Europe’s forest area has increased 5 million ha since the late 1960s. The growing stock has increased 43% and the net annual increment 55% in exploitable forests since 1950. A part of the reported increase is caused by sampling inventories, which have been made in greater part of the countries. Sampling inventories have corrected earlier underestimates of the growing stock and the increment.

The difference between the annual net increment and fellings has increased since 1950. The net increment, 584 million m3, exceeded fellings, 408 million m3, by 176 million m3, in exploitable forests in 1990. If fellings could be increased to equal the increment, Europe would be an exporter of forest products.

A greater increase in the density, in the age and in the mean volume of forests per hectare threaten the biological stability of the growing stock. Degrading of the stock, increasing natural losses and deteriorating environmental qualities of forests can only be prevented by increased fellings and by forest regeneration.

The PDF includes an abstract in Finnish.

  • Kuusela, ORCID ID:E-mail:
article id 7091, category Article
August Renvall. (1923). Das radiale Schwindmass des lappländischen Kiefernstammholzes gemäss dem Verhalten von Bohrspänen. Acta Forestalia Fennica vol. 26 no. 3 article id 7091. https://doi.org/10.14214/aff.7091
English title: The degree of radial shrinkage of pine stem wood from Lapland according to behavior of increment cores.
English keywords: increment core; shrinkage; stem wood; pine

Shrinking of timber when drying is a phenomenon that causes variation in measuring of timber in timber trade and on using the timber for construction or other purposes.   

The data for the article consists of 332 increment core samples from pine trees different ages, sizes and growth rate. There were collected in years 1910-1912 in Finnish Lapland, regions Utsjoki and Inari. The increment cores were collected on the height of 1.3 meters in south-north direction straight crosswise through the whole tree. The samples are 6mm thick. The diameter of the samples was measured immediately after making the sample and after several years’ storage in room temperatures. Also the age of the trees was determined.

The results are presented in tables. The degree of shrinkage varies heavily between the samples but stays anyhow between 1.5 and 3.9%. The mean degree of shrinkage for 314 samples was 2.9%. The results seem to indicate that the bigger the shrinkage the denser the annual growth ring system of the tree, meaning the slower the growth has been.  The older and of diameter bigger trees shrink less than younger and smaller trees. 

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

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

The PDF includes an abstract in Finnish and French.

  • Velling, ORCID ID:E-mail:
  • Nepveu, ORCID ID:E-mail:
article id 4770, category Article
Kustaa Seppälä. (1968). Ennakkotuloksia suometsiköiden ojituksen jälkeisestä kehityksestä ja siihen vaikuttavista tekijöistä. Silva Fennica vol. 2 no. 3 article id 4770. https://doi.org/10.14214/sf.a14555
English title: Preliminary results of post-drainage development of peatland stands in Finland.

The present paper is a preliminary report of a project designed to determine the order of profitability of various forest improvement measures – seeding and planting, drainage, and fertilization – in various types of stands and in different parts of the country on drained peatlands. Sample plot data on the effect of draining on increment was derived from areas drained 28– 36 years ago. The study was carried out in the southern half of Finland.

The observations on increment changes are based on two measurements of the sample stands 12 years apart. Supplementary calculations indicate that the stands on drained peatland, depending on site quality and tree species, have either continued to grow like mineral-soil sites of similar fertility or have somewhat increased their growth rate.

The effect of draining intensity was studied using strip measurements. It was found that both the total amount of wood produced (current stand + cutting removal + natural removal) and the current annual volume increment for the 5-year period systematically decrease as the ditch interval increases. The decrease is, however, relatively slight. In Eriophorum vaginatum pine swamps, the total amount of wood produced and the increment show a decrease of ca. 20% with an increase in ditch interval from 20 to 60 metres. In other sites, the decrease is ca. 5-10%

It can be concluded that if the increase in ditch interval do not result in considerably poorer timber assortment distributions than indicates by stand production and increment, it is profitable to pan for a relatively large ditch interval and a slightly smaller than maximum wood production. Supplementary data and check calculations may cause some changes in these preliminary results.

The PDF includes a summary in English.

  • Seppälä, ORCID ID:E-mail:
article id 7685, category Article
Risto Ojansuu. (1993). Prediction of Scots pine increment using a multivariate variance component model. Acta Forestalia Fennica no. 239 article id 7685. https://doi.org/10.14214/aff.7685

Diameter and volume increment as well as change in stem form of Scots pine (Pinus sylvestris L.) were analysed to predict tree increment variables. A stem curve set model is presented, based on prediction of the diameters at fixed angles in a polar coordinate system. This model consists of three elementary stem curves: 1) with bark, 2) without bark, and 3) without bark five years earlier. The differences between the elementary stem curves are the bark curve and the increment curve. The error variances at fixed angles and covariances between the fixed angles are divided into between-stand and within-stand components. Using principal components, the between-stand and within-stand covariance matrices are condensed separately for stem curve with bark, bark curve and increment curve. The two first principal components of the bark curve describe the vertical change in Scots pine bark type and the first principal component of the increment curve describes the increment rate. The elementary stem curves, bark curve and increment curve as well as corresponding stem volumes, bark volume and volume increment can be predicted for all trees in the stand with free choice of sample tree measurements. When only a few sample trees are measured, the stem curve set model gives significantly more accurate predictions of bark volume and volume increment for tally trees than does the volume method, which is based on the differences between two independent predictions of volume. The volume increment of tally trees can be predicted as reliably with as without measurement of sample tree height increment.

The PDF includes a summary in English.

  • Ojansuu, ORCID ID:E-mail:
article id 7614, category Article
Leo. Heikurainen. (1980). Kuivatuksen tila ja puusto 20 vuotta vanhoilla ojitusalueilla. Acta Forestalia Fennica no. 167 article id 7614. https://doi.org/10.14214/aff.7614
English title: Drainage condition and tree stands on peatlands drained 20 years ago in Finland.

The aim of this investigation was to examine the dependence of stand volume and increment on different growth factors on drained peatlands drained 20 years ago. Measurements were made in 1977-79 on 35 sample plots in Central Finland on relatively poor pine bogs with a thick peat layer.

It became evident that the stand volume, increment and radial growth and growth development are primarily functions of groundwater depth. Groundwater depth is dependent, in the first place, on ditch depth and ditch condition. With regard to the variation in ditch spacing (ca. 35-70 m) under examination, the effect of ditch spacing on the stand was insignificant. As a practical recommendation it was concluded that ditches should be kept deep enough (> 70 cm) in order to maintain undisturbed stand development.

The PDF includes a summary in English.

  • Heikurainen, ORCID ID:E-mail:
article id 7597, category Article
Aarne Nyyssönen, Kari Mielikäinen. (1978). Metsikön kasvun arviointi. Acta Forestalia Fennica no. 163 article id 7597. https://doi.org/10.14214/aff.7597
English title: Estimation of stand increment.

The paper concerns the estimation of the increment of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands in the southern half of Finland. For the methods based on stand tables, tree functions forecasting the annual increment of diameter and height during the next 5-year period are presented. The main results of the study, however, are the functions for the volume increment percentage of pine and spruce stands. The independent variables are: forest site type, tree species, stand age and volume, and mean diameter. The standard error of estimate is about 17% in the best functions. Calculations were made also with regard to the application of the results in growth estimation of large forest areas.

The PDF includes a summary in English.

  • Nyyssönen, ORCID ID:E-mail:
  • Mielikäinen, ORCID ID:E-mail:
article id 7597, category Article
Aarne Nyyssönen, Kari Mielikäinen. (1978). Metsikön kasvun arviointi. Acta Forestalia Fennica no. 163 article id 7597. https://doi.org/10.14214/aff.7597
English title: Estimation of stand increment.

The paper concerns the estimation of the increment of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands in the southern half of Finland. For the methods based on stand tables, tree functions forecasting the annual increment of diameter and height during the next 5-year period are presented. The main results of the study, however, are the functions for the volume increment percentage of pine and spruce stands. The independent variables are: forest site type, tree species, stand age and volume, and mean diameter. The standard error of estimate is about 17% in the best functions. Calculations were made also with regard to the application of the results in growth estimation of large forest areas.

The PDF includes a summary in English.

  • Nyyssönen, ORCID ID:E-mail:
  • Mielikäinen, ORCID ID:E-mail:
article id 7566, category Article
Leo Heikurainen, Kustaa Seppälä. (1973). Ojitusalueiden puuston kasvun jatkumisesta ja alueellisuudesta. Acta Forestalia Fennica no. 132 article id 7566. https://doi.org/10.14214/aff.7566
English title: Regional variation and continuity of stand growth in old forest drainage areas.

The study deals with the development during the 1950s and 1960s of a stand growing on peatlands which had been drained in the 1930s. The following characters were determined by measurements: the volume of the growing stock, the volume increment, the relative increment, the increment percent and the increment curves. Moreover, the possible changes taking place in the difference between tree growth along the ditches and in the middle of the strip between ditches were studied. In addition, the regional variation in increment was studied; this question was studied as the regression between the relative growth and the temperature sum. The results were compared with other Finnish investigations into the regional variation of increment.

The volumes of the growing stock had increased during the course of twelve years by 70–10 m3 /ha depending on the site type and climatic zone concerned. The relative increment had dropped in each case studied. As a matter of fact, this is only to be expected because the volumes had increased and the absolute growth had remained more or less unchanged. The development of the increment percent was compared with mineral soil stands in the case of Southern Finland, both uncut stands and stands treated with cuttings. According to the results obtained, the development of the increment percent was better in the present material than in uncut forests, but in some cases it did not reach the level of tended stands. The revival of the tree crop after draining takes place at different rates in the vicinity of and, on the other hand, at greater distances from the ditches and that this relationship is dependent on the fertility of the site.

The PDF includes a summary in English.

  • Heikurainen, ORCID ID:E-mail:
  • Seppälä, ORCID ID:E-mail:
article id 7566, category Article
Leo Heikurainen, Kustaa Seppälä. (1973). Ojitusalueiden puuston kasvun jatkumisesta ja alueellisuudesta. Acta Forestalia Fennica no. 132 article id 7566. https://doi.org/10.14214/aff.7566
English title: Regional variation and continuity of stand growth in old forest drainage areas.

The study deals with the development during the 1950s and 1960s of a stand growing on peatlands which had been drained in the 1930s. The following characters were determined by measurements: the volume of the growing stock, the volume increment, the relative increment, the increment percent and the increment curves. Moreover, the possible changes taking place in the difference between tree growth along the ditches and in the middle of the strip between ditches were studied. In addition, the regional variation in increment was studied; this question was studied as the regression between the relative growth and the temperature sum. The results were compared with other Finnish investigations into the regional variation of increment.

The volumes of the growing stock had increased during the course of twelve years by 70–10 m3 /ha depending on the site type and climatic zone concerned. The relative increment had dropped in each case studied. As a matter of fact, this is only to be expected because the volumes had increased and the absolute growth had remained more or less unchanged. The development of the increment percent was compared with mineral soil stands in the case of Southern Finland, both uncut stands and stands treated with cuttings. According to the results obtained, the development of the increment percent was better in the present material than in uncut forests, but in some cases it did not reach the level of tended stands. The revival of the tree crop after draining takes place at different rates in the vicinity of and, on the other hand, at greater distances from the ditches and that this relationship is dependent on the fertility of the site.

The PDF includes a summary in English.

  • Heikurainen, ORCID ID:E-mail:
  • Seppälä, ORCID ID:E-mail:
article id 7559, category Article
Kustaa Seppälä. (1972). Ditch spacing as a regulator of post-drainage stand development in Norway spruce and in pine swamps. Acta Forestalia Fennica no. 125 article id 7559. https://doi.org/10.14214/aff.7559

The paper is based on data collected from 411 sample plots in various parts of Finland situated on peatlands which had been drained in the 1930's. The purpose of the study was to determine the influence of ditch spacing on the volume, increment and structure of timber crops growing on drained peatlands. The ditches had been spaced 70–90 m apart, and the sample plots were placed strip wise along the ditches.

The results of the study indicate that the influence of ditch spacing on both the total volume and the volume increment is greater, the poorer the site. On the other hand, the influence of ditch spacing on the structure of the stand as described by means of the mean diameter as weighted by the basal area, seems to be of similar magnitude in all the sites covered by the study.

Generally speaking, the influence of ditch spacing on stand development is surprisingly small, even in extreme cases. The total volume and the increment of the growing stock decrease by about 20% when the ditch spacing increases from 20 to 60 m, the corresponding decrease in the mean diameter having a magnitude of 10%. This was interpreted to be due to the fact that the main part of the superior growth along the margin of the ditch is spent in compensating for the space lost in the area taken up by the ditches.

On the basis of the results obtained it was concluded that the best solution in forest drainage from the economic viewpoint is to employ relatively wide ditch spacings, which leads to a rate of stand development somewhat below the potential.

The PDF includes a summary in Finnish.

  • Seppälä, 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:
article id 4725, category Article
Carl Olof Tamm. (1965). Some experiences from forest fertilization trials in Sweden. Silva Fennica no. 117 article id 4725. https://doi.org/10.14214/sf.a14283
Original keywords: lannoitus; kasvu; turvekankaat; Ruotsi

The many unsolved questions concerning fertilization makes it difficult to forecast accurately its biological and economic consequences. Some of the problems are discussed in this paper. The most common types of forests in Sweden, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands on well-drained mineral soil, respond strongly to nitrogenous fertilizers, but the effect of phosphate, potash or lime is small or nil, at least within 5–10 years after application. The response of nitrogen lasts 4–5 years in pine and somewhat more in spruce.

Drained peatlands usually respond to mineral fertilization, but the improvement brought about by a PK application depends, inter alia, on the nitrogen content of the peat. Peatlands with a peat low in nitrogen need NPK fertilization. For deep peatlands, a moderate or high nitrogen content, a single PK application improves growth conditions for a very long time. Experience of fertilizing shallow peatlands and poorly-drained mineral soil is very limited, but it seems easy to get a growth response either with nitrogen alone or with NPK.

The results of fertilization at the time of planting have not, as a rule, been very good in Sweden. An exception is the afforestation of abandoned fields on drained deep peat, where PK fertilizer around the plant seems to be essential for both survival and growth.

  • Tamm, ORCID ID:E-mail:
article id 4723, category Article
Toivo Matilainen. (1965). Kasvutappiosta ja sen määrittämisestä Etelä-Suomen talousmetsissä. Silva Fennica no. 117 article id 4723. https://doi.org/10.14214/sf.a14281
English title: The increment loss and its determination in economically exploited forests in Southern Finland.

The present study is an attempt to clarify the decrease in growth, or the increment loss, caused by sudden reduction of growth of the growing stock below a certain level, and to find a method for its determination. Increment loss is defined as a decrease in growth during the rotation due to a deficient stock volume. The material consists of Koivisto’s yield tables for repeatedly thinned stands in Southern Finland, and the results of the Third National Forest Inventory concerning the mean volume and increment in the productive sites.

For the calculation of increment loss three formulae were constructed where the increment loss is calculated 1) as the difference between the removal by thinnings in normally developed stands during a time equal with the period of deficient stock and the suddenly removed stock, 2) according to the compound interest calculation principle as the sum of the differences which are obtained by subtracting from the removal in each thinning during the period of deficient stock its initial value, and 3) as the straight interest of the stock deficiency during the period of deficient stock.

According to the calculations, the increment loss is greatest in stands to be grown, viz. 50 m3 solid measure excluding bark per hectare tended Norway spruce stands on Oxalis-Myrtillus type sites at 40% deficiency below minimum stock. In stands to be regenerated the losses are, too, greatest in the similar stands. It exceeds 200 m3/ha when stands younger than 50 years have to been regenerated and the removal amounts to 50% of the stock. In stands to be regenerated the increment loss for spruce, due to the slow initial development by the species, is greater than for Scots pine and birch. The loss is the same at different period of age if the relative deficiency of the stock is of equal size.

According to the study, each stand has a characteristic variation in the increment loss which depends mainly on the relative degree of deficiency from the minimum stock. The formulae and methods can be used to determine the increment loss in average and better stands in Southern Finland when the stock suddenly decreases.

The PDF includes a summary in English.

  • Matilainen, ORCID ID:E-mail:
article id 4673, category Article
M. T. Rogers. (1957). Ring-shadows. Silva Fennica no. 93 article id 4673. https://doi.org/10.14214/sf.a9120

A picture of growth rings of a tree can be obtained on paper by placing it over a disc of a trunk or stump and rubbing it with a pencil. The ‘shadows’, while not yielding the complex data obtainable from the actual wood, do show the proportion of the growth rings composed of spring wood and the denser summer wood. It is possible to collect large amount of data by using an unexperienced staff cheaply and quickly, and the samples may be mailed at little expense. The method may be used to study the previous cuttings of a stand from stumps. The shadowing of tree rings is possible to do even from rather decayed stumps.

The article includes a Finnish abstract.

  • Rogers, ORCID ID:E-mail:
article id 4652, category Article
Kullervo Kuusela. (1956). Hakkuilla käsiteltyjen koivikoiden rakenteesta ja kasvusta. Silva Fennica no. 90 article id 4652. https://doi.org/10.14214/sf.a9115
English title: On the structure and growth of birch stands treated with cutting.

The study is continuation of the earlier structure and growth studies of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) in Forest Research Institute. The material represents birch stands (Betula verrucosa, now B. pendula, and B. Pubescens L.) in Southern Finland. The stands were treated with different fellings, and in regard to their silvicultural condition classified as good, satisfactory and unsatisfactory. Height of the trees, height of living crown, volume, increment and volume increment and development of stem diameter series was measured.

The most characteristic difference between the silviculturally good and poor stands was that the the annual increment of the good stands concentrated into large size trees, and the increment of unsatisfactory stands into small and inferior trees.

It is concluded that if the aim of stand treatment is to produce large and high quality volume increment, the most favourable stand volume of  birch stands, compared with naturally normal stand volume, seems to be 90-85% at the age of 41-55 years, and 80-70% at the age of 56-65 years. If growth of large size trees is aimed at, the maximum number of the dominant trees per hectares cannot be more than 400 at the age of 50-60 years.

The article includes a summary in English.

  • Kuusela, ORCID ID:E-mail:
article id 4600, category Article
Aarne Nyyssönen. (1950). Vertailevia havaintoja hoidettujen ja luonnontilaisten männiköiden rakenteesta ja kehityksestä. Silva Fennica no. 68 article id 4600. https://doi.org/10.14214/sf.a9091
English title: Comparative study on structure and development of managed and natural Scots pine stands.

The Forest Research Institute of Finland has established permanent sample plots to survey the effect of thinnings on the stands. This study compares the development of tended and natural Scots pine (Pinus sylvestris L.) stands growing on three different forest types: Oxalis-Myrtillus, Vaccinium and Calluna site type. The effect of heavy thinning from below (Oxalis-Myrtillus and Vaccinium site types) and increment felling (Calluna site type) was assessed by dividing the trees of the stands in tree classification classes according to their crown storey and defects.

The results show that thinning from below and increment thinning increase the proportion of trees in the 1st crown storey, which is already large in the natural stands. Also the diameter distribution is more even and the mean diameter higher after the thinnings.

In Scots pine stands in natural state, volume increment per stem is highest in the 1st crown storey and diminishes strongly towards the lower crown storeys. Thinnings increased the increment. The study indicates that many of the objectives of the intermediate cuttings, including promoting the growth of the best trees and improving the quality of the stand, have in general been achieved. Consequently, the thinnings give means to achieve the most valuable yield in the stand.

The article includes a summary in English.

  • Nyyssönen, ORCID ID:E-mail:
article id 4551, category Article
Yrjö Ilvessalo. (1939). Metsikön kasvun arvioiminen. Silva Fennica no. 52 article id 4551. https://doi.org/10.14214/sf.a13958
English title: Assessment of forest growth.

Silva Fennica issue 52 includes presentations held in professional development courses, arranged for foresters working in public administration in 1938. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.

This presentation describes different methods of assessing tree growth.

  • Ilvessalo, ORCID ID:E-mail:

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