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Silva Fennica 1926-1997
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Acta Forestalia Fennica
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Articles containing the keyword 'Abies'.

Category: Research article

article id 10076, category Research article
Tore Skrøppa, Arne Steffenrem. (2019). Genetic variation in phenology and growth among and within Norway spruce populations from two altitudinal transects in Mid-Norway. Silva Fennica vol. 53 no. 1 article id 10076. https://doi.org/10.14214/sf.10076
Highlights: Norway spruce populations distributed along each of two altitudinal transects showed strong clinal relationships between the annual mean temperatures of the sites of the populations and height and phenology traits in short term tests and height in field trials; Large variation was present among families within populations for height and phenology traits and with a wider range within than among populations; Correlation patterns among traits were different for provenances and families.

Progenies from open pollinated cones collected in natural populations of Norway spruce (Picea abies (L.) Karst.) distributed along two altitudinal transects in Mid-Norway were tested in the nursery, in short term tests and in long-term field trials. The populations showed clinal variation related to the mean annual temperatures of the populations, with the earliest bud flush and cessation of shoot elongation and lowest height at age nine years for the high altitude populations. Within population variation was considerable as the narrow sense heritability for these traits was 0.67, 0.31 and 0.09 in one transect and 0.55, 0.18 and 0.14 in the other transect, respectively. Lammas shoots occurred in the short term trials with large variation in frequency between years. There was significant family variation for this trait, but also interactions between populations and year. The variance within populations was considerably larger in the populations from low altitude compared to the high-altitude populations. Significant genetic correlations between height and phenology traits and damage scores indicate that families flushing early and ceasing growth late were taller. Taller families also had higher frequencies of damages. Selection of the top 20% families for height growth in short term tests at age nine years gave a simulated gain of 11% increased height growth at age 18 years in long term trials at altitudes similar to those of origin of the populations. The gain was negative when high altitude populations were selected based on testing in the lowland.

  • Skrøppa, Norwegian Institute of Bioeconomy Research, P.O. Box 115, 1431 Ås, Norway ORCID ID:E-mail: tore.skroppa@nibio.no (email)
  • Steffenrem, ORCID ID:E-mail:
article id 10055, category Research article
Jaakko Repola, Hannu Hökkä, Hannu Salminen. (2018). Models for diameter and height growth of Scots pine, Norway spruce and pubescent birch in drained peatland sites in Finland. Silva Fennica vol. 52 no. 5 article id 10055. https://doi.org/10.14214/sf.10055
Highlights: Tree growth strongly correlated with site drainage status; Between-tree competition had a higher impact on tree diameter growth than on height growth; Growth predicted by the constructed models were calibrated using NFI11 data to ensure generally applicable growth predictions level in whole country.

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

  • Repola, Natural Resources Institute Finland (Luke), Natural resources, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: jaakko.repola@luke.fi (email)
  • Hökkä, Natural Resources Institute Finland (Luke), Natural resources, Paavo Havaksen tie 3, FI-90014 University OF Oulu, Finland ORCID ID:E-mail: hannu.hokka@luke.fi
  • Salminen, Natural Resources Institute Finland (Luke), Natural resources, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: hannu.salminen@luke.fi
article id 10013, category Research article
Hardo Becker, Jürgen Aosaar, Mats Varik, Gunnar Morozov, Kristiina Aun, Ülo Mander, Kaido Soosaar, Veiko Uri. (2018). Annual net nitrogen mineralization and litter flux in well-drained downy birch, Norway spruce and Scots pine forest ecosystems. Silva Fennica vol. 52 no. 4 article id 10013. https://doi.org/10.14214/sf.10013
Highlights: The net nitrogen mineralization (NNM) flux in drained peat soils depends largely on the C/N ratio and tree species; The soil NNM process is affected by trees through organic litter input into soil; Pine stand in low-fertility drained transitional bog is dominated by net ammonification; Birch and spruce stands on the fertile drained peat soil with higher pH and N content are dominated by net nitrification.

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

  • Becker, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: hardo.becker@emu.ee (email)
  • Aosaar, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: jyrgen.aosaar@emu.ee
  • Varik, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: mats.varik@emu.ee
  • Morozov, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: gunnar.morozov@emu.ee
  • Aun, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: kristiina.aun@emu.ee
  • Mander, Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, Ülikooli 18, 50090 Tartu, Estonia ORCID ID:E-mail: ulo.mander@ut.ee
  • Soosaar, Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, Ülikooli 18, 50090 Tartu, Estonia ORCID ID:E-mail: kaido.soosaar@ut.ee
  • Uri, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia ORCID ID:E-mail: veiko.uri@emu.ee
article id 9980, category Research article
Eino Levkoev, Lauri Mehtätalo, Katri Luostarinen, Pertti Pulkkinen, Anatoly Zhigunov, Heli Peltola. (2018). Development of height growth and frost hardiness for one-year-old Norway spruce seedlings in greenhouse conditions in response to elevated temperature and atmospheric CO2 concentration. Silva Fennica vol. 52 no. 3 article id 9980. https://doi.org/10.14214/sf.9980
Highlights: Elevated temperature resulted in increased height growth, delayed onset and shortened duration of autumn frost hardiness development in Norway spruce seedlings; Elevated temperature increased variation between genotypes in height growth and frost hardiness development; Elevated atmospheric CO2 concentration had no effect on the development of height or autumn frost hardiness in Norway spruce seedlings.

The mean temperature during the potential growing season (April–September) may increase by 1 °C by 2030, and by 4 °C, or even more, by 2100, accompanied by an increase in atmospheric CO2 concentrations of 536–807 ppm, compared to the current climate of 1981–2010, in which atmospheric CO2 is at about 350 ppm. This may affect both the growth and frost hardiness of boreal trees. In this work, we studied the responses of height and autumn frost hardiness development in 22 half-sib genotypes of one-year-old Norway spruce (Picea abies (L.) Karst.) seedlings to elevated temperatures and atmospheric CO2 concentration under greenhouse conditions. The three climate treatments used were: T+1 °C above ambient and ambient CO2; T+4 °C above ambient and ambient CO2; and T+4 °C above ambient and elevated CO2 (700 ppm). The height growth rate and final height were both higher under T+4 °C compared to T+1 °C. Temperature increase also delayed the onset, and shortened the duration, of autumn frost hardiness development. Elevated CO2 did not affect the development of height or frost hardiness, when compared to the results without CO2 elevation under the same temperature treatment. Higher temperatures resulted in greater variation in height and frost hardiness development among genotypes. Three genotypes with different genetic backgrounds showed superior height growth, regardless of climate treatment; however, none showed a superior development of autumn frost hardiness. In future studies, clonal or full-sib genetic material should be used to study the details of autumn frost hardiness development among different genotypes.

  • Levkoev, 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: eino.levkoev@uef.fi (email)
  • Mehtätalo, University of Eastern Finland, Faculty of Science and Forestry, School of Computing, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: lauri.mehtatalo@uef.fi
  • Luostarinen, 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: katri.luostarinen@uef.fi
  • Pulkkinen,  Natural Resources Institute Finland (Luke), Production systems, Haapastensyrjä Breeding Station, FI-16200 Läyliäinen, Finland ORCID ID:E-mail: pertti.pulkkinen@luke.fi
  • Zhigunov, Saint-Petersburg State Forest Technical University, Forestry Faculty, RU-194021, Institutskiy per. 5, Saint-Petersburg, Russia ORCID ID:E-mail: a.zhigunov@bk.ru
  • Peltola, 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: heli.peltola@uef.fi
article id 9946, category Research article
Frauke Fedderwitz, Niklas Björklund, Velemir Ninkovic, Göran Nordlander. (2018). Does the pine weevil (Hylobius abietis) prefer conifer seedlings over other main food sources? Silva Fennica vol. 52 no. 3 article id 9946. https://doi.org/10.14214/sf.9946
Highlights: Adult pine weevils feed on seedlings and mature conifers, but cause economic damage only on seedlings; Their feeding preferences for branches and roots over seedlings were tested in a laboratory experiment; The only clear preference was for Norway spruce roots; Results support new approaches of seedling protection attempting to redirect pine weevils from planted seedlings to other food sources.

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

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

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

  • Egbäck, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, 230 53 Alnarp, Sweden ORCID ID:E-mail: samuel.egback@slu.se (email)
  • Karlsson, Skogforsk, Ekebo, 268 90 Svalöv, Sweden ORCID ID:E-mail: bo.karlsson@skogforsk.se
  • Högberg, Skogforsk, Ekebo, 268 90 Svalöv, Sweden ORCID ID:E-mail: karl-anders.hogberg@skogforsk.se
  • Nyström, Swedish University of Agricultural Sciences, Department of Forest Resource Management, Skogsmarksgränd, 901 83 Umeå, Sweden ORCID ID:E-mail: kenneth.nystrom@slu.se
  • Liziniewicz, Skogforsk, Ekebo, 268 90 Svalöv, Sweden ORCID ID:E-mail: Mateusz.Liziniewicz@skogforsk.se
  • Nilsson, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, 230 53 Alnarp, Sweden ORCID ID:E-mail: urban.nilsson@slu.se
article id 7759, category Research article
Jaana Luoranen, Sirkka Sutinen. (2017). Reduced height of short day induced bud scale complex may partly explain early bud burst in Norway spruce seedlings. Silva Fennica vol. 51 no. 5 article id 7759. https://doi.org/10.14214/sf.7759
Highlights: Short day treatment used in tree seedling nurseries affects the structure of apical buds; Changes in bud structure may partly explain early bud burst and may be a reason for unburst buds of short day treated seedlings.

Short day (SD) treatment is used as a dormancy induction in forest tree seedling nurseries in the boreal forest zone. However, SD treatment has caused early bud burst in the following spring, which may expose the seedlings to spring frosts. Because the mechanisms affecting earlier bud burst in SD treated seedlings are not fully understood yet, here we have studied the effect of SD treatment on the structure of buds in Norway spruce [Picea abies (L.) Karst.] seedlings. Seedlings were exposed to SD treatments or natural (CTRL) light and photoperiod in July in a nursery in Central Finland. The experiments included two lots of seedlings over two summers and the analyses were done under a stereo microscope. SD treatment advanced initiation of bud scales and formation of needle primordia, and thus the formation period was shorter in CTRL seedlings. In mature buds, no differences in primordial shoots were found between the treatments, whereas notable differences were found in bud scales. The SD buds had fewer and shorter bud scales than the CTRL buds. This led to significantly shorter bud scale complex and, consequently, to shorter buds in SD than in CTRL seedlings. Buds and needles matured earlier in SD treated seedlings. In the following spring, the primordial shoots started to elongate in both treatments around mid-May, when the SD buds started to break down, whereas CTRL buds started to break down in late May. The fewer number and shorter height of protective bud scales may expose buds to harsh winter temperatures and early loss of scales may predispose the SD buds to spring frosts.

  • Luoranen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: jaana.luoranen@luke.fi (email)
  • Sutinen, ORCID ID:E-mail: sirusuti@gmail.com
article id 7748, category Research article
Dominik Bayer, Hans Pretzsch. (2017). Reactions to gap emergence: Norway spruce increases growth while European beech features horizontal space occupation – evidence by repeated 3D TLS measurements. Silva Fennica vol. 51 no. 5 article id 7748. https://doi.org/10.14214/sf.7748
Highlights: Analysis of the closure dynamics of a Norway spruce, a European beech and a mixed forest gap by repeated TLS measurements; Norway spruce allocated additional resources predominantly into DBH growth and displayed stronger resilience against mechanical crown damage; European beech allocated resources towards space occupation and displayed higher crown plasticity; Species mixture had no significant effect.

The reach of different tree species’ crowns and the velocity of gap closure during the occupation of canopy gaps resulting from mortality and thinning during stand development determine species-specific competition and productivity within forest stands. However, classical dendrometric methods are rather inaccurate or even incapable of time- and cost-effectively measuring 3D tree structure, crown dynamics and space occupation non-destructively. Therefore, we applied terrestrial laser scanning (TLS) in order to measure the structural dynamics at tree and stand level from gap cutting in 2006 until 2012 in pure and mixed stands of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.). In conclusion, our results suggest that Norway spruce invests newly available above-ground resources primarily into DBH as well as biomass growth and indicate a stronger resilience against loss of crown mass induced by mechanical damage. European beech showed a vastly different reaction, investing gains from additional above-ground resources primarily into faster occupation of canopy space. Whether our sample trees were located in pure or mixed groups around the gaps had no significant impact on their behavior during the years after gap cutting.

  • Bayer, Address Technical University of Munich (TUM), Chair for Forest Growth and Yield Science, Hans-Carl-von-Carlowitz-Platz 2, 85354, Freising, Germany ORCID ID: http://orcid.org/0000-0002-2084-3019 E-mail: dominik.bayer@lrz.tu-muenchen.de (email)
  • Pretzsch, Address Technical University of Munich (TUM), Chair for Forest Growth and Yield Science, Hans-Carl-von-Carlowitz-Platz 2, 85354, Freising, Germany ORCID ID:E-mail: hans.pretzsch@lrz.tu-muenchen.de
article id 1740, category Research article
Ram P. Sharma, Zdeněk Vacek, Stanislav Vacek. (2017). Modelling tree crown-to-bole diameter ratio for Norway spruce and European beech. Silva Fennica vol. 51 no. 5 article id 1740. https://doi.org/10.14214/sf.1740
Highlights: Modelled crown-to-bole diameter ratio (CDBDR) using tree and stand-level predictors, and sample plot random effects; Spatially explicit mixed-effects model described the largest part of CDBDR variation with no significant trend in the residuals; The CDBDR increased with increasing stand development stage and site quality, but decreased with decreasing proportion of the species of interest, and increasing competition.

Crown dimensions are correlated to growth of other parts of a tree and often used as predictors in growth models. The crown-to-bole diameter ratio (CDBDR), which is a ratio of maximum crown width to diameter at breast height (DBH), was modelled using data from permanent sample plots located on Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica L.) stands in different parts of the Czech Republic. Among various tree and stand-level measures evaluated, DBH, height to crown base (HCB), dominant height (HDOM), basal area of trees larger in diameter than a subject tree (BAL), basal area proportion of the species of interest (BAPOR), and Hegyi’s competition index (CI) were found to be significant predictors in the CDBDR model. Random effects were included using the mixed-effects modelling to describe sample plot-level variation. For each species, the mixed-effects model described a larger part of the variation of the CDBDR than nonlinear ordinary least squares model with no trend in the residuals. The spatially explicit mixed-effects model showed more attractive fit statistics [conditional R2 ≈ 0.73 (spruce), 0.78 (beech)] than its spatially inexplicit counterpart [conditional R2 ≈ 0.71 (spruce), 0.76 (beech)]. The model showed that CDBDR increased with increasing HDOM – a measure that combines the stand development stage and site quality – but decreased with increasing HCB and competition (increasing BAL and CI), and decreasing proportions of the species of interest (increasing BAPOR). For both species, the spatially explicit mixed-effects model should be a preferred choice for a precise prediction of the CDBDR. The CDBDR model will have various management implications such as determination of spacing, stand basal area, stocking, and planning of appropriate species mixture.

  • Sharma, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16521, Praha 6 – Suchdol, Czech Republic ORCID ID:E-mail: sharmar@fld.czu.cz (email)
  • Vacek, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16521, Praha 6 – Suchdol, Czech Republic ORCID ID:E-mail: vacekz@fld.czu.cz
  • Vacek, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16521, Praha 6 – Suchdol, Czech Republic ORCID ID:E-mail: vacekstanislav@fld.czu.cz
article id 5662, category Research article
Samuel Egbäck, Urban Nilsson, Kenneth Nyström, Karl-Anders Högberg, Nils Fahlvik. (2017). Modeling early height growth in trials of genetically improved Norway spruce and Scots pine in southern Sweden. Silva Fennica vol. 51 no. 3 article id 5662. https://doi.org/10.14214/sf.5662
Highlights: The developed height growth model based on unimproved material predicted the development relatively well for genetically improved Norway spruce; For genetically improved Scots pine, however, the model needed to be modified; By incorporating a genetic component into the Scots pine model, the prediction errors were reduced.

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

  • Egbäck, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, 230 53 Alnarp, Sweden ORCID ID:E-mail: samuel.egback@slu.se (email)
  • Nilsson, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, 230 53 Alnarp, Sweden ORCID ID:E-mail: urban.nilsson@slu.se
  • Nyström, Swedish University of Agricultural Sciences, Department of Forest Resource Management, Skogsmarksgränd, 901 83 Umeå, Sweden ORCID ID:E-mail: kenneth.nystrom@slu.se
  • Högberg, Skogforsk, Ekebo, 268 90 Svalöv, Sweden ORCID ID:E-mail: karl-anders.hogberg@skogforsk.se
  • Fahlvik, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, 230 53 Alnarp, Sweden ORCID ID:E-mail: nils.fahlvik@slu.se
article id 1781, category Research article
Petr Čermák, Michal Rybníček, Tomáš Žid, Kjell Andreassen, Isabella Børja, Tomáš Kolář. (2017). Impact of climate change on growth dynamics of Norway spruce in south-eastern Norway. Silva Fennica vol. 51 no. 2 article id 1781. https://doi.org/10.14214/sf.1781
Highlights: Correlations between tree-ring width and climate parameters showed temporal instability in their relationship during the period 1915–2012; A statistically significant positive correlation of April–May precipitation on tree-ring growth was identified since the mid-1970s; The concomitant temperature increase may have contributed to the changes of growth dynamics.

The ongoing climate change may have a distinct effect on Norway spruce growth, one of the most important tree species in European forest management. Therefore, the understanding and assessment of climate-growth relationship can help to reveal relevant patterns in temporal variability that may result in lower tree vitality and decline. The main objective of our study was to evaluate the long-term climate-growth variability of Norway spruce in south-eastern Norway, at the northern edge of the temperate zone. We sampled in total 270 dominant and co-dominant trees from 18 plots in south-eastern Norway. We analysed stem cores and evaluated crown condition parameters to assess the retrospective tree growth and vitality. Despite considerable differences in the crown parameters, high similarity among tree-ring width (TRW) series allowed compiling the regional tree-ring width chronology. Correlations between TRW and climate parameters showed temporal instability in their relationship during the period 1915–2012. While we did not detect any significant relationships between TRW and climate parameters in the first half of the study period (1915–1963), a significant correlation between TRW and spring precipitation was observed for the period 1964–2012. This shift appeared concurrent with temperatures reaching above-average values compared to the average of the climate normal period 1961–1990.

  • Čermák, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: cermacek@mendelu.cz (email)
  • Rybníček, 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
  • Žid, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic ORCID ID:E-mail: tom.z@centrum.cz
  • Andreassen, Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail: Kjell.Andressen@nibio.no
  • Børja, Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail: Isabella.Borja@nibio.no
  • Kolář, 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
article id 1312, category Research article
Simon Karl Nils Berg, Tomas Nordfjell, Dan Bergström. (2015). Effect of stump size and timing of stump harvesting on ground disturbance and root breakage diameter. Silva Fennica vol. 49 no. 5 article id 1312. https://doi.org/10.14214/sf.1312
Highlights: The ground disturbance and root breakage diameter during conventional stump harvesting on mineral soil were quantified; A function for estimating the disturbed area based on stump size was constructed; Many fine roots were found to be harvested; The total ground disturbance at the site after stump harvesting was similar to that caused by soil scarification.

Stump wood is a possible alternative to fossil fuel. Its harvesting, however, disturbs the ground and this has not yet been quantified at stump level. Such disturbance is likely to be dependent on stump size, type of soil and timing of stump harvesting. Therefore, we measured ground disturbance and root breakage diameter at two Norway spruce sites with sandy glacial till soil. The sites were harvested with a fork type head, 6 and 18 months after clear cutting. Measurements were made within 2 weeks of harvest. No difference was found between the two sites. The mean area of disturbed ground was 6.06 (std 3.14) m2 per stump and increased exponentially with stump size. A regression function modelling the relationship was constructed. Unexpectedly, many fine roots where extracted in the harvest. The arithmetic and basal area weighted mean root breakage diameter was 4.6 (std 2.2) and 29.5 (std 17.9) mm, respectively. There seems to be a limited increase in root breakage diameter with increased stump size. The small root breakage diameter is associated with reduced fuel quality and greater nutrient removal. It appears that much of the ground disturbance is associated with the creation of ruts rather than stump harvest per se. Stump harvesting disturbs a larger percentage of the area of a harvested site than mounding. Postponing stump harvest by one year did not decrease the ground disturbance or increase the root breakage diameter. To achieve less disturbance and larger root breakage diameter, probably new stump harvesting technology is required.

  • Berg, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID:E-mail: phd.simon.berg@gmail.com (email)
  • Nordfjell, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID:E-mail: tomas.nordfjell@slu.se
  • Bergström, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID:E-mail: dan.bergstrom@slu.se
article id 1408, category Research article
Anna Katharina Franke, Pasi Aatsinki, Ville Hallikainen, Esa Huhta, Mikko Hyppönen, Vesa Juntunen, Kari Mikkola, Seppo Neuvonen, Pasi Rautio. (2015). Quantifying changes of the coniferous forest line in Finnish Lapland during 1983–2009. Silva Fennica vol. 49 no. 4 article id 1408. https://doi.org/10.14214/sf.1408
Highlights: Volume of the growing stock of spruce and pine has increased in forests and in timber lines during the past 26 years; Spruce stem numbers increased on average, while pine stem numbers remained stable and location-specific variation was observed; Presuming that the ongoing trend of increasing temperature will remain, the enhanced forest regeneration and growth may result in extension of forests in the future.

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

  • Franke, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: anna.franke@fau.de (email)
  • Aatsinki, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: pasi.aatsinki@luke.fi
  • Hallikainen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: ville.hallikainen@luke.fi
  • Huhta, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: esa.huhta@luke.fi
  • Hyppönen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: mikko.hypponen@luke.fi
  • Juntunen, The Sámi Education Institute, Menesjärventie 4, P.O. Box 50, FI-99871 Inari, Finland ORCID ID:E-mail: vesa.juntunen@sogsakk.fi
  • Mikkola, Natural Resources Institute Finland (Luke), Economics and society, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: kari.mikkola@luke.fi
  • Neuvonen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 68, FI-80101, Joensuu, Finland ORCID ID:E-mail: seppo.neuvonen@luke.fi
  • Rautio, Natural Resources Institute Finland (Luke), Bio-based business and industry, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: pasi.rautio@luke.fi
article id 1337, category Research article
Leszek Bujoczek, Małgorzata Bujoczek, Jan Banaś, Stanisław Zięba. (2015). Spruce regeneration on woody microsites in a subalpine forest in the western Carpathians. Silva Fennica vol. 49 no. 3 article id 1337. https://doi.org/10.14214/sf.1337
Highlights: The occurrence probability of Picea abies seedlings on fallen deadwood was found to increase with diameter and decay stage of deadwood and with the volume of living trees, and to decrease with the density of living trees, sapling density, and land slope. It was also higher on stumps with greater diameter and in plots with higher sapling density, but decreased with increasing stump height.

The density of Picea abies [L.] Karst. regeneration on different microsites, the quantity and quality of woody microsites, and seedling occurrence probability on stumps and fallen deadwood were studied in a subalpine forest that has been under protection for approximately 30–40 years (Gorce Mountains in the western Carpathians). Thirty percent of seedlings and 29% of saplings grew on stumps and fallen deadwood, while the remaining regeneration occurred on soil surface and mounds created by uprooted trees. The occurrence probability of Picea seedlings on fallen deadwood increased with deadwood diameter and decay stage and with the volume of living trees, and decreased with increased density of living trees, sapling density, and land slope. Furthermore, seedlings were more likely to grow on stumps with a greater diameter and in plots with higher sapling density, but less likely to grow on higher stumps. Stumps and fallen deadwood covered about 4% of the forest floor, but the material that is most important for promoting regeneration (strongly decomposed logs and those of a diameter exceeding 30 cm) took up only about 22 m2 ha-1. We have concluded that in a subalpine forest that has been protected for 30–40 years regeneration processes take place mostly on soil surface and stumps. The role of fallen deadwood increases over time as a greater number of suitable logs (in terms of size and decay stage) become available.

  • Bujoczek, University of Agriculture in Krakow, ORCID ID:E-mail: lbujoczek@gmail.com (email)
  • Bujoczek, University of Agriculture in Krakow, ORCID ID:E-mail: bujoczek.m@gmail.com
  • Banaś, University of Agriculture in Krakow, ORCID ID:E-mail: rlbanas@cyf-kr.edu.pl
  • Zięba, University of Agriculture in Krakow, ORCID ID:E-mail: rlzieba@cyf-kr.edu.pl
article id 1279, category Research article
Andreas Kreutz, Tuomas Aakala, Russell Grenfell, Timo Kuuluvainen. (2015). Spatial tree community structure in three stands across a forest succession gradient in northern boreal Fennoscandia. Silva Fennica vol. 49 no. 2 article id 1279. https://doi.org/10.14214/sf.1279
Highlights: We studied the tree community spatial structure in three 1.2-ha plots representing naturally developed northern boreal forests of varying ages; Spatial structure showed little differences between the mid-successional, late-successional and old-growth stands; The occurrence of Picea abies relative to Betula spp. indicated a mosaic-like spatial assembly; Mosaics are likely maintained by species-specific replacement, not reciprocal replacement as thought earlier.
Development of species composition during succession is well studied in natural boreal forests, but empirical assessments of how within-stand spatial structure develops in late-successional stages are few. Here, we quantified spatial patterns in three unmanaged stands consisting of Picea abies (L.) Karst. and Betula pubescens Ehrh. and Betula pendula Roth (hereafter Betula spp.) in northern boreal Fennoscandia. We conducted a comprehensive analysis of small-scale spatial point patterns in three fully mapped 1.2-ha sample plots, representing different forest developmental stages: mid-successional, late-successional and old-growth forest. We used several variants of Ripley’s K-function to analyze the spatial point patterns along the successional gradient. Univariate analyses showed that mature trees of both species were either randomly distributed or clumped. P. abies saplings were clumped, and Betula spp. saplings occurred in a random or clumped manner. In the bivariate analyses, saplings were more likely to be found in the surroundings of mature trees of the same species, but occurred independent of the individuals of other tree species. Mature trees showed interspecific repulsion. Only modest differences occurred in the univariate patterns between the three successional stages, but in the bivariate analyses the most evident patterns, i.e. intraspecific attraction and interspecific repulsion, were stronger in the older successional stages. Overall, the studied stands appear structured as species-specific mosaics. These mosaics, along with mixed species composition, seem to be maintained by species self-replacement, which contrasts with findings from earlier studies.
  • Kreutz, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: andreas.kreutz@wald-rpl.de
  • Aakala, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID: http://orcid.org/0000-0003-0160-6410 E-mail: tuomas.aakala@helsinki.fi (email)
  • Grenfell, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: russell.grenfell@gmail.com
  • Kuuluvainen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: timo.kuuluvainen@helsinki.fi
article id 1300, category Research article
Jaana Luoranen, Risto Rikala. (2015). Post-planting effects of early-season short-day treatment and summer planting on Norway spruce seedlings. Silva Fennica vol. 49 no. 1 article id 1300. https://doi.org/10.14214/sf.1300
Highlights: Summer planting and short-day treatment advanced the bud burst and increased the height of Norway spruce seedlings after planting, compared to autumn and spring planted or untreated seedlings.
Effects of short-day (SD) treatment on bud burst, growth and survival of Norway spruce (Picea abies [L.] Karst.) container seedlings after summer planting were studied in an experiment established in Suonenjoki, Central Finland. One-year-old seedlings were SD-treated for three weeks starting on 18 June, 24 June and 8 July 2004 and then planted on 22 July, 5 August, 6 September 2004 and, as a normal spring planting, on 10 May, 2005. Untreated control seedlings were also planted on these dates. Second flush on the planting year and bud burst the following spring was monitored in planted seedlings, whereas seedling height and survival were determined at the end of growing seasons 2004–2006. We observed a non-significant risk of a second flush if seedlings were SD-treated on 18 June. Also, SD-treated seedlings planted in July or August showed advanced bud burst and increased height the following growing season without significant effects on survival, compared to autumn and spring planted seedlings. Planting in July or early August was associated with a significant increase in the incidence of multiple leaders in later years. Based on our results, to begin a three-week SD treatment in late June or early July and then plant seedlings in late July or early August could be a good practice.
  • Luoranen, Natural Resources Institute Finland (Luke), Natural resources and bioproduction, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: jaana.luoranen@luke.fi (email)
  • Rikala, The Finnish Forest Research Institute, Suonenjoki Unit, Suonenjoki, Finland ORCID ID:E-mail: rikala@dnainternet.fi
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 1192, category Research article
Hannu Hökkä, Hanna Mäkelä. (2014). Post-harvest height growth of Norway spruce seedlings in northern Finland peatland forest canopy gaps and comparison to partial and complete canopy removals and plantations. Silva Fennica vol. 48 no. 5 article id 1192. https://doi.org/10.14214/sf.1192
Highlights: Norway spruce seedlings’ height growth recovered within four years after the cutting of canopy gaps; Growth was linearly related to tree height, being highest for tallest seedlings; Seedlings in the 20 m diameter gap and in the central and northern parts in the 15 m diameter gap showed the best growth; In gaps early height growth was 60% of that in peatland spruce plantations but 2–3 times higher than in uneven-aged cut forests.
Recent studies have shown the establishment of Norway spruce (Picea abies (L.) Karst.) to be successful in small canopy gaps cut in drained spruce mire stands in northern Finland. The aim of this study was to quantify seedling height growth in gaps and compare it to that observed in other canopy cuttings and plantations. We sampled spruce crop seedlings (maximum density ca. 3000 ha–1) in the spring of 2013 in a field experiment in which canopy gaps of 10, 15 and 20 m in diameter had been cut in winter 2004. The total seedling height in 2013 and the length of annual shoots over the past five years (2012–2008) were recorded in the survey. Seedling height varied from 20 cm to 2.7 m, with an average of 65 cm. The average annual height growth was 7.1 cm. A mixed linear model analysis was carried out to investigate seedling height growth variation. Seedling height was linearly and positively related to growth. Height growth started to increase in the fifth growing season after cutting. Seedling height growth in the 20 m gap was slightly better than in the smaller ones. In the 15 m gap, both the centrally located seedlings and those located at the northern edge grew best. In the 20 m gap, southerly located seedlings grew more slowly than seedlings in all other locations. The average seedling height growth in this study was about 60% of that in peatland plantations, but comparable to that in mineral soil gaps, and 2–3 times higher than in uneven-age cut stands.
  • Hökkä, Finnish Forest Research Institute, Rovaniemi Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: hannu.hokka@metla.fi (email)
  • Mäkelä, Lapland University of Applied Sciences, Jokiväylä 11 C, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: hanna.makela@edu.ramk.fi
article id 1135, category Research article
Matts Lindbladh, Per-Ola Hedwall, Ida Wallin, Annika M. Felton, Henrik Böhlenius, Adam Felton. (2014). Short-rotation bioenergy stands as an alternative to spruce plantations: implications for bird biodiversity. Silva Fennica vol. 48 no. 5 article id 1135. https://doi.org/10.14214/sf.1135
Highlights: There is a gap in knowledge regarding the biodiversity implications of replacing production forests with bioenergy stands; We compared the avian biodiversity of early rotation hybrid aspen stands and spruce plantations, the latter being the dominant production forest type in southern Sweden; Our results indicate that young hybrid aspen stands can support relatively diverse and distinctive bird communities.
Global efforts to decrease dependence on fossil fuels have increased interest in bioenergy production. One source of bioenergy is fast growing deciduous tree species, such as hybrid aspen (Populus × wettsteinii Hämet-Ahti). The majority of research on hybrid aspen which assesses biodiversity implications, has however primarily focused on agricultural lands as the reference condition. This has resulted in a substantial gap in our knowledge regarding the biodiversity implications of replacing production forest types with hybrid aspen, a form of reforestation taking place in northern Europe. In this study we address this knowledge gap by comparing the avian biodiversity of young hybrid aspen and spruce (Picea abies L.) plantations of similar age, the latter being the most prevalent forestry alternative in in southern Sweden. We found that hybrid aspen stands had higher bird species richness and abundance as well as a distinct community composition compared to the spruce stands. We suggest that the most likely driver was the greater structural and tree species complexity in the aspen stands, provided for by the fenced exclusion of ungulates from the regenerating hybrid aspen stands. Our results indicate that at least during early stages of regeneration, and in comparison to the dominating production forest type in the region, hybrid aspen stands can support relatively high levels of bird diversity, and a bird species composition more closely associated with broadleaf habitat types requiring restoration in this region.
  • Lindbladh, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: matts.lindbladh@slu.se (email)
  • Hedwall, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: per-ola.hedwall@slu.se
  • Wallin, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: ida.wallin@slu.se
  • Felton, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: annika.felton@slu.se
  • Böhlenius, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: henrik.bohlenius@slu.se
  • Felton, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: adam.felton@slu.se
article id 989, category Research article
Anna Saarsalmi, Pekka Tamminen, Mikko Kukkola. (2014). Effects of long-term fertilisation on soil properties in Scots pine and Norway spruce stands. Silva Fennica vol. 48 no. 1 article id 989. https://doi.org/10.14214/sf.989
Highlights: N fertilisation increased the amount of carbon in the organic layer; N fertilisation decreased the C/N ratio in the surface soil; N addition increased the amount of most nutrients in the organic layer; N fertilisation tended to lower pH, although only slightly.
The response of surface soil after 45- to 52-years to repeated nitrogen and phosphorus fertilisation was studied. This study included 30 factorial experiments established in young (5- to 30-year-old) stands using plots of 900 m2, on average, and by randomising treatments within each experiment. Total amount of N added varied from 534 to 1908 kg ha–1 and that of P from 69 to 193 kg ha–1, repeated at every second N fertilisation. Liming was performed twice; in total, 6000 kg ha–1 of dolomite was applied. Nitrogen fertilisation increased the mass of the organic layer and the amount of carbon and consequently the amounts of most of the elements in the organic layer. In both the organic layer and the 0–10 cm layer of mineral soil, nitrogen fertilisation decreased the C/N ratio and tended to lower pH, although only slightly. Phosphorus fertilisation increased the amounts of P and Ca. Liming increased the total amounts of most elements in the organic layer, except for C and N. We were able to derive models to describe how changes in the chemical properties of the surface soil depended on doses of elements and on site and stand properties.
  • Saarsalmi, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: anna.saarsalmi@metla.fi (email)
  • Tamminen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: pekka.tamminen@metla.fi
  • Kukkola, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: mikko.kukkola@metla.fi
article id 949, category Research article
Ken Olaf Storaunet, Jørund Rolstad, Erlend Rolstad. (2014). Effects of logging on the threatened epiphytic lichen Usnea longissima: an experimental approach. Silva Fennica vol. 48 no. 1 article id 949. https://doi.org/10.14214/sf.949
Highlights: A re-inventory of the threatened lichen Usnea longissima in ten Norway spruce forest stands where experimental selective loggings had been conducted 5 to 8 years before revealed that the number of lichen thalli had increased with 34%; The number of thalli increased more where the forest was open whether or not the low tree density was caused by the loggings.
Usnea longissima Ach. is a circumboreal epiphytic lichen draping tree canopies in moist coastal and mountainous forests. It is extinct from many European and North-American localities, presumably due to industrial forestry and air pollution, but still has a stronghold in parts of Scandinavia and U.S. and Canadian Pacific Northwest. In 2005/06 we used a comparative and retrospective approach to evaluate how present and historic tree and stand characteristics influenced the occurrence and abundance of the lichen (Storaunet et al. 2008). In 2012, we re-inventoried ten Norway spruce forest stands with 401 U. longissima-bearing trees and recorded changes in the number of U. longissima thalli. Seven of the stands had been experimentally, selectively logged 5–8 years before, where the lichen-bearing trees had been marked in the field and were avoided during the logging operation. Total number of lichen-bearing trees decreased slightly (2.9%), whereas the number of thalli had increased with 34%. Number of thalli increased more where the forest was open (low basal area, m2ha-1) whether or not the low tree density was caused by the logging events. At high tree densities the change in number of thalli was negligible. We suggest that selective logging, securing lichen-bearing trees, may be a viable management option to keep tree density from becoming too dense, thereby enhancing growth and establishment of U. longissima.
  • Storaunet, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail: stk@skogoglandskap.no (email)
  • Rolstad, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail: roj@skogoglandskap.no
  • Rolstad, Skogfaglig Rådgivning, Holmsida 126, NO-1488 Hakadal, Norway ORCID ID:E-mail: roe@skogoglandskap.no
article id 933, category Research article
Per-Ola Hedwall, Harald Grip, Sune Linder, Lars Lövdahl, Urban Nilsson, Johan Bergh. (2013). Effects of clear-cutting and slash removal on soil water chemistry and forest-floor vegetation in a nutrient optimised Norway spruce stand. Silva Fennica vol. 47 no. 2 article id 933. https://doi.org/10.14214/sf.933
Fertilisation with nutrient optimisation has in Sweden resulted in large increases in volume growth in young stands of Norway spruce. There are, however, environmental concerns about repeated fertilisation and one is the risk of nutrient leakage to ground water resources and aquatic ecosystems after clear-cutting of such forests. The present study followed soil-water chemistry in optimised fertilised stands after clear-cutting, as well as effects of harvest of slash on nutrient leakage. Parts of a 30-year-old stand of Norway spruce, which had been subject to a nutrient optimisation experiment for 17 years, were clear-cut. A split-plot design with whole-tree harvesting as the sub-plot treatment was applied. Lysimeters were installed and soil-water sampled at nine occasions during the following four years. No significant effects of fertilisation on nitrate leaching were found, while harvest of slash reduced the concentration of Ca, DOC, DON, K, Mg, ammonium and nitrate, as well as pH in the soil solution. While no effects of fertilisation could be seen on the soil water concentration of N, the results indicate an interaction between fertilisation and harvest of slash on the concentration of nitrate in the soil solution. The results indicate that forest-floor vegetation plays an important role in the retention of N after clear-cutting of fertilised forests.
  • Hedwall, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences (SLU), P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: per-ola.hedwall@slu.se (email)
  • Grip, Department of Forest Ecology and Management, SLU, SE-901 83 Umeå, Sweden ORCID ID:E-mail: harald@grip2.se
  • Linder, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences (SLU), P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: sune.linder@slu.se
  • Lövdahl, Department of Forest Ecology and Management, SLU, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Nilsson, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences (SLU), P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: urban.nilsson@slu.se
  • Bergh, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences (SLU), P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: johan.bergh@slu.se
article id 893, category Research article
Juha Heiskanen, Timo Saksa, Jaana Luoranen. (2013). Soil preparation method affects outplanting success of Norway spruce container seedlings on till soils susceptible to frost heave. Silva Fennica vol. 47 no. 1 article id 893. https://doi.org/10.14214/sf.893
Soil preparation is a common practice that precedes outplanting of Norway spruce (Picea abies (L.) Karst.) in Finland as it enhances the survival and early growth of seedlings. Mounding in particular has become more common with Norway spruce planting in recent years. However, on fine-grained soils, the postplanting performance of seedlings has been poorer than on coarser soils even with mounding. This study examined the effects of different soil preparation treatments (spot and ditch mounding with varying mound height, inverting, unprepared control with or without a herbicide) on the postplanting performance of Norway spruce container seedlings on till soil susceptible to frost heave in two outplanting forest sites in central Finland. The results indicate higher soil temperature and lower soil water content especially in the highest mounds. Mounds, however, subsided gradually during the study years. Seedling mortality was higher and the proportion of vigorous seedlings was lower in the unprepared treatments, mainly due to increased pine weevil (Hylobius abietis L.) damage. Frost heave was present mainly on ditch mounded and inverted spots. Glyphosate herbicide treatment showed no benefit compared to the untreated control in two years. Consequently, seedling damage and conditions in the planting spots were reflected in seedling growth which was enhanced in the mounded spots. However, varying mound height or thickness of mineral capping showed no clear difference in seedling growth. The results therefore suggest that ditch or spot mounding should be used on frost heave susceptible forest soils to promote plantation establishment. Inverting or having no soil preparation with or without herbicide is not recommended.
  • Heiskanen, Finnish Forest Research Institute, Suonenjoki Unit, Juntintie 154, FI-77600, Suonenjoki, Finland ORCID ID:E-mail: juha.heiskanen@metla.fi (email)
  • Saksa, Finnish Forest Research Institute, Suonenjoki Unit, Juntintie 154, FI-77600, Suonenjoki, Finland ORCID ID:E-mail: timo.saksa@metla.fi
  • Luoranen, Finnish Forest Research Institute, Suonenjoki Unit, Juntintie 154, FI-77600, Suonenjoki, Finland ORCID ID:E-mail: jaana.luoranen@metla.fi
article id 920, category Research article
Hannu Hökkä, Jaakko Repola, Mikko Moilanen, Markku Saarinen. (2012). Seedling establishment on small cutting areas with or without site preparation in a drained spruce mire – a case study in northern Finland. Silva Fennica vol. 46 no. 5 article id 920. https://doi.org/10.14214/sf.920
A large proportion of drained spruce mire stands is currently approaching regeneration maturity in Finland. We studied the effect of cutting – small canopy openings (78, 177, and 314 m2) and small clear-cuts (0.25–0.37 ha) – with or without site preparation (scalping) on the establishment of natural Norway spruce seedlings in one experimental drained spruce mire stand in northern Finland. The cuttings were made in winter 2004–2005 and site preparation with scalping in early June 2005. The experimental design was composed of four blocks with altogether four clear-cuts and 33 canopy openings. The seedling establishment was surveyed annually (2006, 2008–2010) from five circular sample plots (one 10 m2 and four 5 m2 plots in size) located within the canopy openings and from 18 circular 5 m2 sample plots systematically located in the scalped and untreated halves of the clear-cuts. Site preparation was found unnecessary, because it resulted in a clearly lower number of seedlings in the openings. A slight negative effect was also found in the clear-cuts. In the two years following the cuttings, the number of seedlings increased quickly in the canopy openings, but more gradually in the clear-cut areas. In 2010, on average 15 500 new seedlings were observed in the canopy openings and 6700 in the clear-cut areas, of which 5050 and 1200, respectively, were >0.1 m tall spruces. The proportion of birch increased in the last two years, being ca. 22% in the openings and 45% in the clear-cuts in 2010. The spatial distribution of seedlings was more uneven in the clear-cuts than in the openings, with 41% and 20% of survey plots empty, respectively.
  • Hökkä, Finnish Forest Research Institute, Rovaniemi Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: hannu.hokka@metla.fi (email)
  • Repola, Finnish Forest Research Institute, Rovaniemi Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: jaakko.repola@metla.fi
  • Moilanen, Finnish Forest Research Institute, Oulu Unit, P.O. Box 413, FI-90014 University of Oulu, Finland ORCID ID:E-mail: mikko.moilanen@metla.fi
  • Saarinen, Finnish Forest Research Institute, Parkano Unit, Kaironiementie 15, FI-39700 Parkano, Finland ORCID ID:E-mail: markku.saarinen@metla.fi
article id 917, category Research article
Anna Gunulf, Rebecka Mc Carthy, Jonas Rönnberg. (2012). Control efficacy of stump treatment and influence of stump height on natural spore infection by Heterobasidion spp. of precommercial thinning stumps of Norway spruce and birch. Silva Fennica vol. 46 no. 5 article id 917. https://doi.org/10.14214/sf.917
An alternative precommercial thinning technique results in trees being cut higher up the stem compared to the normal method using a brush saw. The aims of this study were to investigate if primary infection of Heterobasidion spp. on precommercial thinning stumps of Norway spruce and birch is influenced by stump height and to test the control efficacy of stump treatment with Phlebiopsis gigantea on precommercial thinning stumps of Norway spruce. Small Norway spruce and birch trees were felled on five sites in southern Sweden and their stumps subjected to natural spore infection. For each species, two treatments of stump height were created: 15 and 100 cm. Half of the Norway spruce stumps were treated with P. gigantea. After two months, 896 stumps were sampled and infection by Heterobasidion spp. was quantified. The height of stumps did not significantly influence infection frequency or size of infection on either tree species. Untreated Norway spruce stumps had an infection frequency of 55% while 31% of the treated stumps were infected. The control efficacy of stump treatment in terms of reduced relative infected area was 61–65%. The area occupied by Heterobasidion spp. on birch stumps was generally small, on average 0.4 cm2 per infected stump, although 15% of the stumps were infected. The risk of primary infection in Norway spruce dominated stands should be considered when precommercial thinning is conducted but the control efficacy and economy of stump treatment warrants further investigation before practical recommendations can be made.
  • Gunulf, Swedish University of Agricultural Sciences, Department of Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: anna.gunulf@slu.se (email)
  • Mc Carthy, Skogsforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden ORCID ID:E-mail: Rebecka.McCarthy@skogforsk.se
  • Rönnberg, Swedish University of Agricultural Sciences, Department of Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: jonas.ronnberg@slu.se
article id 441, category Research article
Ane Zubizarreta-Gerendiain, Petri Pellikka, Jordi Garcia-Gonzalo, Veli-Pekka Ikonen, Heli Peltola. (2012). Factors affecting wind and snow damage of individual trees in a small management unit in Finland: assessment based on inventoried damage and mechanistic modelling. Silva Fennica vol. 46 no. 2 article id 441. https://doi.org/10.14214/sf.441
In this work, we assessed the factors affecting wind and snow damage of individual trees in a small management unit in western Finland. This was done based on inventoried damage and observed wind speeds and snow loading in storms Pyry and Janika in 2001 and Mielikki in 2002 together with mechanistic model. First, we studied which factors explain the observed damage in individual trees. Secondly, we studied how well the mechanistic model (HWIND) could predict the wind speed needed to uproot individual trees at the margins of permanent upwind edges. We found that Pyry storm caused 70% and Janika and Mielikki 18 and 12% of observed damage. In Janika storm, all trees uprooted. In other storms, both uprooting and stem breakage occurred. Scots pine suffered the most damage. Recently thinned stands on the upwind edges of open areas suffered the most damage. But, damage occurred also on soils with relatively shallow anchorage. HWIND predicted correctly damage for 69% of all uprooted trees. No-uprooting was correctly predicted for 45 and 19% of standing trees (all Scots pines), which were measured within and at the immediate upwind edge of same stands. HWIND model needs further validation at the permanent edges and/or on soils with shallow rooting to improve its prediction accuracy in such conditions.
  • Zubizarreta-Gerendiain, Technical University of Lisbon, School of Agriculture, Forest Research Centre, Lisbon, Portugal ORCID ID:E-mail:
  • Pellikka, University of Helsinki, Dept. of Geosciences and Geography, Helsinki, Finland ORCID ID:E-mail:
  • Garcia-Gonzalo, Technical University of Lisbon, School of Agriculture, Forest Research Centre, Lisbon, Portugal ORCID ID:E-mail:
  • Ikonen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
  • Peltola, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail: heli.peltola@uef.fi (email)
article id 54, category Research article
Urban Nilsson, Björn Elfving, Kjell Karlsson. (2012). Productivity of Norway spruce compared to Scots pine in the interior of northern Sweden. Silva Fennica vol. 46 no. 2 article id 54. https://doi.org/10.14214/sf.54
Productivity of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) was studied in 12 paired plots in the interior of northern Sweden. Stands were established between 1928 and 1959; yield plots were established between 1974 and 1983 during pre-commercial thinning of the stands. Gross stem-wood production was significantly higher for Scots pine than for Norway spruce, stem-wood production by Norway spruce being 29.4% that of Scots pine. The site index for Norway spruce was lower than for Scots pine at all sites except one; the average difference in site index was 4.8 m. The simulated maximum mean annual increment (MAImax) during the rotation was 19% higher than the MAImax estimated with the site index for Scots pine, whereas simulated MAImax and MAImax estimated from the site index was about the same for Norway spruce. The simulations also indicated that MAI peaked about 50 years later for Norway spruce than for Scots pine. More small trees were included in the diameter distribution of Norway spruce than of Scots pine resulting in a lower stem-wood volume for Norway spruce when stands with the same dominant height were compared. This study shows that the difference in growth and rotation length between Scots pine and Norway spruce has implications when choosing which species to grow in the interior of northern Sweden.
  • Nilsson, Swedish University of Agricultural Sciences (SLU), Southern Swedish Forest Research Centre, Alnarp, Sweden ORCID ID:E-mail: urban.nilsson@slu.se (email)
  • Elfving, SLU, Forest Ecology and Management, Umeå, Sweden ORCID ID:E-mail:
  • Karlsson, SLU, Unit of Field Based Research, Asa, Sweden ORCID ID:E-mail:
article id 67, category Research article
Pentti Niemistö, Heikki Korpunen, Ari Laurén, Marika Salomäki, Jori Uusitalo. (2012). Impact and productivity of harvesting while retaining young understorey spruces in final cutting of downy birch (Betula pubescens). Silva Fennica vol. 46 no. 1 article id 67. https://doi.org/10.14214/sf.67
Quite often Norway spruce (Picea abies (L.) Karsten) forms an understorey in birch dominated stands in Finland. Advantageous growth conditions for both storeys are present especially in downy birch (Betula pubescens Ehrh.) stands on drained fertile peatland. The most common way of regenerating mature Downy birch forest is clear cutting and replanting with Norway spruce, even if vital spruce seedlings or saplings was already growing under the birch. The aim of this study is to investigate the impact of retaining young understorey spruces on the productivity of harvesting and on the quality of the remaining stands in downy birch dominated stands with modern cut-to-length (CTL) machinery. Retaining undergrowth spruces decreased productivity of cutting in managed stands (600 stems/ha) by 6–9 per cent and in unmanaged stands (1200 stems/ha) by 11–17 per cent compared with clear cutting, where the understorey is not considered. Compared with the case where no understorey was present, the decrease in productivity was 10–17 per cent and 21–30 per cent respectively. In forwarding, retaining the undergrowth decreased the productivity of loading phases by 7–14 per cent. Harvesting treatment where spruces were retained produced an adequate stand structure for the future growing stock. Using this method, 14–24 per cent of the original spruces were totally destroyed while 25–44 per cent of spruces were destroyed when they were not considered for harvesting. The spatial variation of the remaining spruces was much better in the treatment where spruces were retained. Our study results shows that in this kind of two storey birch–spruce forests, the harvesting treatment where spruces are retained while cutting is the most acceptable and profitable method. It allows for a vital spruce sapling to continue growing, and avoids regeneration and tending costs or other harmful effects of clear-cut areas such as the freezing of young spruce plants and an increase in the ground water table.
  • Niemistö, Finnish Forest Research Institute, Parkano & Joensuu, Finland ORCID ID:E-mail:
  • Korpunen, Finnish Forest Research Institute, Parkano & Joensuu, Finland ORCID ID:E-mail:
  • Laurén, Finnish Forest Research Institute, Parkano & Joensuu, Finland ORCID ID:E-mail:
  • Salomäki, Finnish Forest Research Institute, Parkano & Joensuu, Finland ORCID ID:E-mail:
  • Uusitalo, Finnish Forest Research Institute, Parkano & Joensuu, Finland ORCID ID:E-mail: jori.uusitalo@metla.fi (email)
article id 66, category Research article
Monika Strömgren, Kristina Mjöfors, Björn Holmström, Achim Grelle. (2012). Soil CO2 flux during the first years after stump harvesting in two Swedish forests. Silva Fennica vol. 46 no. 1 article id 66. https://doi.org/10.14214/sf.66
One way of increasing the supply of renewable energy, thereby decreasing the use of fossil fuels, is to extract the stumps that remain after final stem harvesting. However, little is known about the environmental consequences of stump harvesting, and how ecosystem services, such as carbon sequestration, are affected by the practice. In the present paper, the effects on the soil carbon pool during the first months and years after stump harvesting in former Norway spruce stands are presented. The study was performed at two sites in mid- and southern Sweden. At both sites, the soil CO2 flux was measured on several occasions with a portable respiration system, to compare plots on which stump harvesting had occurred, with reference plots. At one of the sites, CO2 exchange was also followed continuously by means of eddy-covariance measurements before and after stump harvesting. Since there was no vegetation at the beginning of the study, almost all emitted CO2 could be assumed to come from heterotrophic sources, and the soil CO2 flux was measured. This study shows that the effect of stump harvesting on CO2 flux or soil decomposition processes is small or absent compared to site preparation such as mounding in a short-term perspective of months and years. The long-term consequences of stump harvesting are, however, still uncertain.
  • Strömgren, Swedish University of Agricultural Sciences, Department of Soil and Environment, Uppsala, Sweden ORCID ID:E-mail: monika.stromgren@slu.se (email)
  • Mjöfors, Swedish University of Agricultural Sciences, Department of Soil and Environment, Uppsala, Sweden ORCID ID:E-mail:
  • Holmström, Swedish University of Agricultural Sciences, Department of Soil and Environment, Uppsala, Sweden ORCID ID:E-mail:
  • Grelle, Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden ORCID ID:E-mail:
article id 87, category Research article
Radek Bace, Miroslav Svoboda, Pavel Janda. (2011). Density and height structure of seedlings in subalpine spruce forests of Central Europe: logs vs. stumps as a favourable substrate. Silva Fennica vol. 45 no. 5 article id 87. https://doi.org/10.14214/sf.87
Decaying logs and stumps provide an important seedling substrate in natural subalpine forests. However, only stumps present such a role in managed forests. The aim of this study was to assess the differences in the process of seedling colonization between logs and stumps. The study was carried out in the Czech Republic, in two old-growth subalpine spruce forests located in the Bohemian Forest and Ash Mts., dominated by Athyrium distentifolium Opiz and Vaccinium myrtillus L. undergrowth, respectively. Norway spruce (Picea abies (L.) Karst.) regeneration growing on logs, stumps and non-coarse woody debris (CWD) microsites was surveyed. Regeneration (height 0–2.0 m) densities exceeded 5000 individuals per ha on both sites. The average density of P. abies regeneration per square meter of substrate was 0.3-5.7-19.6 and 0.5-3.8-11.0 on non-CWD microsites, logs and stumps, located in A. distentifolium and V. myrtillus undergrowth, respectively. Stumps and non-CWD microsites dominated by V. myrtillus, supported a higher proportion of taller seedlings per plot compared to the small seedlings growing on logs and non-CWD dominated by A. distentifolium ground-cover. The disproportion in regeneration densities between the stumps and the original logs decreased with increasing stages of decay. The tallest regeneration growing on stumps (root-soil plates) was significantly older than that growing on the logs (stems). Based on these two latter findings, the stumps appeared to provide suitable seedling substrates several years earlier than the logs did. Therefore, we conclude that the stumps play a more important role (relative to their covered area, 21–28 m2 ha–1) in terms of suitable microsites for regeneration, than the logs do.
  • Bace, Czech University of Life Sciences, Faculty of Forestry and Wood Sciences, Prague, Czech Republic ORCID ID:E-mail: bace@fld.czu.cz (email)
  • Svoboda, Czech University of Life Sciences, Faculty of Forestry and Wood Sciences, Prague, Czech Republic ORCID ID:E-mail:
  • Janda, Czech University of Life Sciences, Faculty of Forestry and Wood Sciences, Prague, Czech Republic ORCID ID:E-mail:
article id 81, category Research article
Tuomas Aakala. (2011). Temporal variability of deadwood volume and quality in boreal old-growth forests. Silva Fennica vol. 45 no. 5 article id 81. https://doi.org/10.14214/sf.81
Reference deadwood volumes from natural forests for forest management and restoration are often derived from one-time measurements or from repeated measurements over short time-scales. Such an approach often assumes an equilibrium state between tree mortality and decomposition, which is questionable in many boreal forest ecosystems due to the occurrence of allogenic disturbances. Using a simulation model based on empirical estimates of tree mortality, disturbance chronologies and models of wood decay class dynamics, this study aimed at characterizing variability in the volume and quality of deadwood for the past 200 years. The variability of deadwood volumes in old-growth forests, arising from differences in disturbance regimes and differing decay rates, was exemplified in two areas of Picea abies-dominated forests in northern Europe. The results imply that with stable deadwood input and slow decay rates the deadwood volume may be in an equilibrium state. On the contrary, if moderate-severity disturbances occur such a state seems improbable. Both study areas displayed continuity in deadwood availability, although temporary paucity in the early decay classes with shortest residence times was also observed. The results stress the importance of understanding the dynamic nature of deadwood in old-growth forests, instead of the traditional view of deadwood as a static ecosystem component.
  • Aakala, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: tuomas.aakala@helsinki.fi (email)
article id 80, category Research article
Mari T. Jönsson, Shawn Fraver, Bengt Gunnar Jonsson. (2011). Spatio-temporal variation of coarse woody debris input in woodland key habitats in central Sweden. Silva Fennica vol. 45 no. 5 article id 80. https://doi.org/10.14214/sf.80
The persistence of many saproxylic (wood-living) species depends on a readily available supply of coarse woody debris (CWD). Most studies of CWD inputs address stand-level patterns, despite the fact that many saproxylic species depend on landscape-level supplies of CWD. In the present study we used dated CWD inputs (tree mortality events) at each of 14 Norway spruce (Picea abies) dominated woodland key habitat sites to analyze the spatial and temporal patterns of CWD additions between 1950 and 2002 within a small landscape in central Sweden. We found that inputs were episodic within sites, where local windstorms created pulses in CWD input. Pulses occurred simultaneously in many sites, yielding landscape-level synchrony of CWD input. These synchronous pulses, and importantly, the breaks between pulses, may have negative implications for saproxylic species that are dependent on large volume inputs of freshly killed Norway spruce. In addition, the inherent small size and relative isolation of these sites may further increase extinction risks due to stochastic events. However, background CWD input rates occurring between pulses varied substantially among sites, presumably the result of the sites’ varied histories and structural characteristics. This finding suggests that the different sites have varied abilities to provide habitat for saproxylic species during periods with low landscape-level input of CWD.
  • Jönsson, Department of Ecology, SLU, P.O. Box 7044, SE-750 07 Uppsala, Sweden (current); Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden ORCID ID:E-mail: mari.jonsson@slu.se (email)
  • Fraver, U.S. Forest Service, Northern Research Station, Grand Rapids, Minnesota, USA (current); Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden ORCID ID:E-mail:
  • Jonsson, Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden ORCID ID:E-mail:
article id 75, category Research article
Silvia Lamedica, Emanuele Lingua, Ionel Popa, Renzo Motta, Marco Carrer. (2011). Spatial structure in four Norway spruce stands with different management history in the Alps and Carpathians. Silva Fennica vol. 45 no. 5 article id 75. https://doi.org/10.14214/sf.75
In Europe most Norway spruce (Picea abies (L.) Karst.) mountain forests have been altered by human activities, leading to a lack of reference condition concerning their original structure. Nonetheless, remnants of Norway spruce primeval forests still exist in the Carpathians. Our objective was to assess the differences in structure between managed and unmanaged stands, concerning diameter distributions, amount of standing deadwood, spatial distributions and spatial structure of trees. We established four permanent plots: one in a virgin forest in the Eastern Carpathians and three in a previously managed forest in the Alps. In each plot, species, DBH, and position of the live and dead standing trees were collected. Spatial distribution and structure of all the trees was analysed through several indices. In the Carpathians forest there are clear signs of natural density-dependent mortality processes whereas in the Alpine plots such dynamics are less evident. In these latter plots, the lower snags volume and the random trees spatial distribution can be considered the legacies of past management. Nonetheless, despite the different history of the four stands, they all seem to converge towards a similar spatial structure with the presence of groups (30–40 m) of trees of similar size.
  • Lamedica, Forest Ecology Research Unit, Dept TeSAF, University of Padova, Legnaro (PD), Italy ORCID ID:E-mail:
  • Lingua, Forest Ecology Research Unit, Dept TeSAF, University of Padova, Legnaro (PD), Italy ORCID ID:E-mail:
  • Popa, Forest Research and Management Institute, Research Station for Norway Spruce Silviculture, Câmpulung Moldovenesc, Romania ORCID ID:E-mail:
  • Motta, Department AGROSELVITER, University of Torino, Grugliasco (TO), Italy ORCID ID:E-mail:
  • Carrer, Forest Ecology Research Unit, Dept TeSAF, University of Padova, Legnaro (PD), Italy ORCID ID:E-mail: marco.carrer@unipd.it (email)
article id 97, category Research article
Hannu Hökkä, Jaakko Repola, Mikko Moilanen, Markku Saarinen. (2011). Seedling survival and establishment in small canopy openings in drained spruce mires in Northern Finland. Silva Fennica vol. 45 no. 4 article id 97. https://doi.org/10.14214/sf.97
A large proportion of drained spruce mire stands is currently approaching regeneration maturity in Finland. Traditional regeneration methods with effective site preparation and planting generally result in satisfactory seedling stands also in spruce mires. However, natural regeneration methods may be more appropriate in protecting watercourses and minimizing regeneration costs. We studied the survival of advance growth and establishment of new seedlings in small canopy openings that were cut at three different diameters in two experimental drained spruce mire stands in Northern Finland (Tervola and Oulu) in 2004. The number of seedlings was repeatedly surveyed from five small circular plots (one 10 m2 and four 5 m2 plots in size) located within the opening. Advance growth which survived the cutting and new seedlings were separated in the surveys. The density of advance growth was on average 9000 ha–1 after cutting, and it decreased by 30% during the five-year monitoring period (2006–2010) due to natural mortality. The number of new seedlings increased rapidly within the three years after cutting the openings. In 2010, 11 000–26 000 new seedlings ha–1 in Tervola and 12 000–16 000 ha–1 in Oulu on average were observed. The size of the opening had no clear effect on the regeneration result. The proportion of birch of the new seedlings increased with time and opening size in Tervola. The results show that Norway spruce regenerates naturally in small canopy openings cut in mature drained spruce mire stands.
  • Hökkä, Finnish Forest Research Institute, Rovaniemi Research Unit, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: hannu.hokka@metla.fi (email)
  • Repola, Finnish Forest Research Institute, Rovaniemi Research Unit, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Moilanen, Finnish Forest Research Institute, Muhos Research Unit, Muhos, Finland ORCID ID:E-mail:
  • Saarinen, Finnish Forest Research Institute, Parkano Research Unit, Parkano, Finland ORCID ID:E-mail:
article id 107, category Research article
Jaana Luoranen, Risto Rikala, Heikki Smolander. (2011). Machine planting of Norway spruce by Bracke and Ecoplanter: an evaluation of soil preparation, planting method and seedling performance. Silva Fennica vol. 45 no. 3 article id 107. https://doi.org/10.14214/sf.107
We evaluated the effects of planting date and planting machine (Bracke: three machines, 69 regeneration areas in three years; Ecoplanter: six areas, two years) on the quality and field performance one and three years after planting of Norway spruce (Picea abies (L.) Karst.) seedlings in central Finland. Both machine types planted on average 1800 seedlings per hectare, and after three years approximately 1600 (Bracke) and 1200 (Ecoplanter) were still alive. This study suggests that planting with a Bracke machine can achieve better regeneration rates than those observed in privately-owned Finnish forests. We characterized the quality of mounding and planting with the Bracke machine as excellent and that of the Ecoplanter as good. The soil preparation method of the Ecoplanter produced humus-rich mounds where seedlings were susceptible to pine weevils and consequently suffered higher mortality. Different machines were used in different regional areas and each machine was operated by different driver/s which may have influenced the results. No negative effects of planting date were observed. Seedling growth decreased if they were tall in relation to their root plug volume, grown too densely in the nursery, and if stored in the field for several months prior to planting. We conclude that mechanized planting is successful when the soil preparation method produces mounds covered by purely mineral soil. Planting from May to the end of September is suitable for seedlings intended for use during this period.
  • Luoranen, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: jaana.luoranen@metla.fi (email)
  • Rikala, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Smolander, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
article id 105, category Research article
Jaana Luoranen, Risto Rikala. (2011). Nutrient loading of Norway spruce seedlings hastens bud burst and enhances root growth after outplanting. Silva Fennica vol. 45 no. 3 article id 105. https://doi.org/10.14214/sf.105
We studied the effects of late season nutrient loading (NLOAD) on the timing of bud burst, growth and changes in nitrogen (N) concentrations in the first growing season after seedlings were outplanted. Two-year-old Norway spruce (Picea abies (L.) Karst.) seedlings with three foliar nitrogen concentration levels (NLOAD levels 11.3, 22.5 and 27.5 g N kg-1 for L, M- and H-seedlings, respectively) were examined in the following three experiments: root growth capacity test (RGC), rooting experiment in the field and soil fertility experiment (‘rich’ or ‘poor’ soil) in the field. Bud burst in RGC was monitored daily and foliar N concentration (field experiments), height and root growth (rooting experiment) at monthly intervals. With respect to the RGC test, no differences in root growth were observed among the three NLOAD levels, but buds of H-seedlings burst 2–6 days earlier than others. In the rooting experiment, nutrient loading increased height and root growth but did not affect the timing of height growth. In the soil fertility experiment, foliar N of H- and M-seedlings decreased rapidly, but the decline was slower in rich soil. Current-year needles had more N in seedlings growing in rich soil and the N concentration declined until height growth ceased whereafter it increased until autumn. Improved growth from nutrient loading seems to last only for the first season after planting and the greatest benefits are enjoyed by seedlings planted in poor soils.
  • Luoranen, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600, Suonenjoki, Finland ORCID ID:E-mail: jaana.luoranen@metla.fi (email)
  • Rikala, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600, Suonenjoki, Finland ORCID ID:E-mail:
article id 113, category Research article
Jinsong Wang, Chunyu Zhang, Fucai Xia, Xiuhai Zhao, Lianhai Wu, Klaus von Gadow. (2011). Biomass structure and allometry of Abies nephrolepis (Maxim) in Northeast China. Silva Fennica vol. 45 no. 2 article id 113. https://doi.org/10.14214/sf.113
Above- and below-ground tree biomass structure and allometric relationships of Abies nephrolepis (Maxim) were assessed in an old secondary forest dominated by A. nephrolepis, Pinus koraiensis, Quercus mongolica, Tilia amurensis, Fraxinus mandshurica and Acer mono in northeast China. Based on the breast-height diameter (D), a total of 21 sample trees were divided into three tree size classes: the small trees (1 cm ≤ D < 10 cm), the medium trees (10 cm ≤ D < 20 cm) and the big trees (D ≥ 20 cm). The greatest amount of live branch biomass was located in the middle and bottom layers of the crown, while the largest foliage biomass was found in the middle layer in each tree size category. The relative contribution of canopy biomass components (live branches and foliage) decreased with increasing tree size, while that of coarse root biomass remained almost constant. The relationship between above- and belowground biomass was linear. D and tree height (H) decreased with increasing competition intensity. The small trees had lower average crown ratio and higher average height-to-diameter ratio than those of the medium and big trees. The big trees had higher average stem to foliage mass ratio than those of the small and medium trees. Crown ratio, height-to-diameter ratio and stem to foliage mass ratio were not correlated with competition intensity in the same tree size class. Root to shoot mass ratio was almost constant among tree sizes. Allometric equations based on D gave higher correlations compared to those with other stem diameters: at tree base, at 30-cm height and at crown base.
  • Wang, Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing 100083, China ORCID ID:E-mail:
  • Zhang, Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing 100083, China ORCID ID:E-mail:
  • Xia, Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing 100083, China ORCID ID:E-mail:
  • Zhao, Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing 100083, China ORCID ID:E-mail: zhaoxh@bjfu.edu.cn (email)
  • Wu, Rothamsted Research, Okehampton, Devon, UK ORCID ID:E-mail:
  • Gadow, Faculty of Forestry and Forest Ecology, Georg-August-University Göttingen, Göttingen, Germany ORCID ID:E-mail:
article id 41, category Research article
Ying Hou, Jintao Qu, Zukui Luo, Chao Zhang, Kaiyun Wang. (2011). Morphological mechanism of growth response in treeline species Minjiang fir to elevated CO2 and temperature. Silva Fennica vol. 45 no. 2 article id 41. https://doi.org/10.14214/sf.41
To test whether and how morphological traits are linked with growth responses of plants to temperature and CO2 is important for understanding the mechanism underlying how plant growth will respond to global warming. In this study, using closed-top chambers to mimic future elevated CO2 and temperature, the growth response, morphological traits of Minjiang fir (Abies faxoniana Rehd.et Wils.) and the relationship of the two were investigated after two years of exposure to the single and combined elevation of CO2 and temperature. The results showed that biomass of Minjiang fir was 21%, 31%, and 35% greater than the control in elevated CO2, elevated temperature and the combination of elevated CO2 and temperature treatments, respectively. Elevated CO2 and temperature significantly affected the morphology of Minjiang fir, and a few morphological traits were highly correlated with growth responses. Larger branch angles at the upper layer, crown volume, and relative crown length contributed to positive growth responses to elevated CO2, while decreased specific leaf area (SLA) constricted any further growth response. Leaf morphological traits were more closely correlated with the response ratio than crown did in the elevated temperature, while in the combination of elevated CO2 and temperature, crown was more correlated with the response ratio than the leaf morphological traits. Thus, our results indicate that morphological traits may contribute differently to growth responses under different experimental conditions.
  • Hou, Department of Life Sciences, Shangqiu Normal University, Shangqiu, China ORCID ID:E-mail:
  • Qu, Department of Life Sciences, Shangqiu Normal University, Shangqiu, China ORCID ID:E-mail:
  • Luo, School of Environment and Life Sciences, Kaili University, Kaili, China ORCID ID:E-mail:
  • Zhang, Shanghai Key Laboratory of Urbanization and Ecological Restoration, East China Normal University, Shanghai, China, and University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
  • Wang, Shanghai Key Laboratory of Urbanization and Ecological Restoration, East China Normal University, Shanghai, China, and University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail: kywang@re.ecnu.edu.cn (email)
article id 123, category Research article
Staffan Jacobson, Folke Pettersson. (2010). An assessment of different fertilization regimes in three boreal coniferous stands. Silva Fennica vol. 44 no. 5 article id 123. https://doi.org/10.14214/sf.123
In 1981–82 three field experiments were established with the aim of elucidating (i) the growth response of middle-aged coniferous stands at different fertilization intensities and, hence, the economic outcomes; and (ii) the need to add nutrients other than nitrogen (N). Nutrient additions were performed at intervals of two, four, six and eight years. The experiments were established on typical podzolized and N-limited mor-humus sites, two in Scots pine (Pinus sylvestris L.) stands and one in a Norway spruce (Picea abies (L.) Karst.) stand, at three different locations in Sweden. The ages of the stands were 65–70 years at the time of establishment. Growth responses were calculated after a 22-year study period. The growth responses were significant in all treatments. The addition of nutrients other than N did not affect stem growth at any of the sites. The growth response tended to increase with decreasing application interval. The results also revealed that the efficiency of fertilization is reduced as the interval between fertilizations is shortened. Accordingly, the growth effect per kg of added N was negatively correlated to fertilization intensity. The least intensive fertilization regime (an eight-year interval) resulted in an average net increase in C sequestration of 35 kg per kg N added. The profitability, in terms of internal rate of return, the present net value at different interest rates and the cost of production, i.e. the cost to produce one extra m3 under the different N regimes, are presented and discussed.
  • Jacobson, Skogforsk, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail: staffan.jacobson@skogforsk.se (email)
  • Pettersson, Skogforsk, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail:
article id 453, category Research article
Eduard Schiessl, Michael Grabner, Gerald Golesch, Thomas Geburek, Silvio Schueler. (2010). Sub-montane Norway spruce as alternative seed source for a changing climate? A genetic and growth analysis at the fringe of its natural range in Austria. Silva Fennica vol. 44 no. 4 article id 453. https://doi.org/10.14214/sf.453
Insights into the intraspecific variation in climate response of forest trees and the utilization of suitable seed sources are required to maintain forest ecoystems under expected climate change. Individuals of Norway spruce with an anomalous spherical-shaped crown were characterized by genetic (using a mtDNA marker) and dendroclimatic analysis. Such trees occur frequently at the fringe of the spruce distribution in east/south-east Austria. We employed pair-wise comparisons between trees with spherical and “regular” conical crowns on 47 sites. No evidence was found for a different phylogeographic history of spherical and conical spruces, but the high allelic diversity at the nad1 locus highlighted the importance of east/south-east Austria as refugium and migration corridor for Norway spruce. Analysis of mean annual increment revealed a larger amount of earlywood within the sapwood area and fewer negative pointer years for spherical spruces than for conical ones, pointing at a higher vitality and smaller interactions between climate and growth for spherical spruces. Although the results cannot explain the anomalous crown form, they suggest spherical trees to have a higher ability to cope the warm and dry climate of the region than “regular” conical spruces. We discuss the origin of spherical crowns in terms of population history and phenotypic plasticity and speculate on possible effects of crown architecture on canopy-atmosphere exchange.
  • Schiessl, Department of Genetics, Research and Training Centre for Forests, Natural Hazards and Landscape, Hauptstrasse 7, A-1140 Vienna, Austria ORCID ID:E-mail:
  • Grabner, Department of Material Sciences and Process Engineering, Institute of Wood Science and Technology, University of Natural Resources and Applied Life Sciences, Peter-Jordan-Strasse 82, A-1190 Vienna, Austria ORCID ID:E-mail:
  • Golesch, Department of Genetics, Research and Training Centre for Forests, Natural Hazards and Landscape, Hauptstrasse 7, A-1140 Vienna, Austria ORCID ID:E-mail:
  • Geburek, Department of Genetics, Research and Training Centre for Forests, Natural Hazards and Landscape, Hauptstrasse 7, A-1140 Vienna, Austria ORCID ID:E-mail:
  • Schueler, Department of Genetics, Research and Training Centre for Forests, Natural Hazards and Landscape, Hauptstrasse 7, A-1140 Vienna, Austria ORCID ID:E-mail: silvio.schueler@bfw.gv.at (email)
article id 135, category Research article
Ola Lindroos, Marina Henningsson, Dimitris Athanassiadis, Tomas Nordfjell. (2010). Forces required to vertically uproot tree stumps. Silva Fennica vol. 44 no. 4 article id 135. https://doi.org/10.14214/sf.135
Stumpwood attracts renewed interest due to increased use of forest biomass for bioenergy. In Nordic countries stumps are generally uprooted with crawler excavators, which have strong cranes (ca. 400 kNm gross lift torque), but are not designed for moving in forest terrain. Their use is based on practical experience with available and tested machine types rather than thorough examinations of requirements, partly due to limited knowledge of force requirements for uprooting of stumps. Therefore, in this work mean and maximum forces required to vertically uproot stumps of Norway spruce (Picea abies) and birch (Betula spp.) were quantified together with the effects of various soil types and uprooting methods. The used excavator’s crane-mounted uprooting device enabled comparisons between usage of solely crane force, and a method in which preparatory loosening forces were applied prior to crane force. Uprooting stumps in single pieces proved difficult; 61% split unintentionally. Force requirements were similar across tree species, increasing curve-linearly with stump diameter, and stumps uprooted in a single piece required more force than split stumps. Preparatory loosening reduced crane force requirements and, surprisingly, less force was required to uproot stumps from a mesic, till soil than from a moist, finer-textured soil. No stump required more than 60 kN crane force and functions for maximum force requirements indicate that powerful harvesters and forwarders (gross crane lifting capacity of 273 and 155 kNm, respectively) should be able to uproot all stumps with ≤ 61 cm and ≤ 32 cm diameter, respectively, in one piece. Larger stumps could be managed if it is acceptable that stumps are split before uprooting.
  • Lindroos, Department of Forest Resource Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden ORCID ID:E-mail: ola.lindroos@srh.slu.se (email)
  • Henningsson, Komatsu Forest AB, Box 7124, SE-907 04 Umeå, Sweden ORCID ID:E-mail:
  • Athanassiadis, Department of Forest Resource Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Nordfjell, Department of Forest Resource Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
article id 146, category Research article
Karri Uotila, Juho Rantala, Timo Saksa, Pertti Harstela. (2010). Effect of soil preparation method on economic result of Norway spruce regeneration chain. Silva Fennica vol. 44 no. 3 article id 146. https://doi.org/10.14214/sf.146
Economic result of forest regeneration chains, based either on spot mounding or on disc trenching and planting of Norway spruce (Picea abies [L.] Karst.) seedlings, were clarified and compared to each other. First, effects of soil preparation method on early development of Norway spruce stands were measured from field experiments. Second, the effects of soil preparation method on stand level management programs were modelled. The modelling was based on growth simulation and investment calculations. The soil preparation methods substantially affected early development of a stand. The density of the removed trees in early cleaning was 56% higher on the disc-trenched area compared to the spot-mounded area. The difference was especially high (120%), close by (< 25 cm) the remained spruce seedlings. There was also a difference between the methods in the growth of crop spruces; at biological age of 8 years, the mean height of spruce was 110 cm on the spot-mounded area and 68 cm on the disc-trenched area. The differences led to divergent management programs between the areas. The disc-trenched area needed three young stand management operations whereas two was enough at the spot-mounded area. Although disc trenching is a less expensive method than spot mounding, the total management costs were higher in disc trenching than in spot mounding. Furthermore, incomes from the first commercial thinning were higher when regeneration based on spot mounding. At the interest rate of 3%, the investment in spot mounding had 329 EUR ha–1 higher net present value than the investment in disc trenching.
  • Uotila, Finnish Forest Research Institute, Suonenjoki, Finland ORCID ID:E-mail: karri.uotila@metla.fi (email)
  • Rantala, Finnish Forest Research Institute, Suonenjoki, Finland ORCID ID:E-mail:
  • Saksa, Finnish Forest Research Institute, Suonenjoki, Finland ORCID ID:E-mail:
  • Harstela, Finnish Forest Research Institute, Suonenjoki, Finland ORCID ID:E-mail:
article id 140, category Research article
Jussi Laurila, Risto Lauhanen. (2010). Moisture content of Norway spruce stump wood at clear cutting areas and roadside storage sites. Silva Fennica vol. 44 no. 3 article id 140. https://doi.org/10.14214/sf.140
Norway spruce (Picea abies (L.) Karst.) stump wood is a potential source of bioenergy in Finland. The heating value of stump wood depends on, among other things, the moisture, carbon and ash content of the wood. In this study the moisture content of Norway spruce stump wood was examined immediately after harvesting at the clear cutting area and after different drying times at the roadside storage sites. Immediately after stump harvesting the average moisture content (wet basis) was 53%. The stump wood dried fairly fast during spring and summer. One month after stump harvesting, the average moisture content was about 31%. If the stump wood had dried well once, water absorption became very weak and the moisture content increased only slightly in the late autumn. Each spring and summer the moisture content of the stumps was lower than during the previous year. Annually the lowest moisture content was observed at the beginning of July and the highest at both the beginning and the end of the year. The moisture content of stump wood followed an upwards opening parabola over a one year period and was repeated each year. Three years after harvesting the heating value of the stump wood was still 5.241 MWh/ton. Overall, when harvesting took place in the spring or early summer, the stump wood was combustible after a one month drying period immediately after harvesting.
  • Laurila, Seinäjoki University of Applied Sciences, School of Agriculture and Forestry, FI-63700 Ähtäri, Finland ORCID ID:E-mail: jussi.laurila@seamk.fi (email)
  • Lauhanen, Seinäjoki University of Applied Sciences, School of Agriculture and Forestry, FI-63700 Ähtäri, Finland ORCID ID:E-mail:
article id 196, category Research article
Aaron R. Weiskittel, Laura S. Kenefic, Robert S. Seymour, Leah M. Phillips. (2009). Long-term effects of precommercial thinning on the stem dimensions, form and branch characteristics of red spruce and balsam fir crop trees in Maine, USA. Silva Fennica vol. 43 no. 3 article id 196. https://doi.org/10.14214/sf.196
The effects of precommercial thinning (PCT) on stem dimensions, form, volume, and branch attributes of red spruce [Picea rubens Sarg.] and balsam fir [Abies balsamea (L.) Mill.] crop trees were assessed 25 years after treatment in an even-aged northern conifer stand. Treatments were a uniform 2.4 x 2.4-m spacing and a control (no PCT). The PCT treatment significantly increased individual tree diameter at breast height (DBH), height growth, crown ratio, and crown width, while it reduced the tree height to DBH ratio. PCT also significantly increased stem taper and consequently, regional volume equations overpredicted observed stem volume by 2 to 15%, particularly for the spaced trees. PCT also increased the number and maximum size of branches on the lower bole. The sizes of knots on half of the sampled spruce crop trees in the spaced plots precluded them from being used as select structural lumber; there were no other effects on log grade. Our findings indicate that PCT can have a long-term influence on the structural attributes of individual trees, and that improved stem-volume prediction equations are needed in the Acadian region of North America.
  • Weiskittel, School of Forest Resources, University of Maine, Orono, ME 04469, USA ORCID ID:E-mail: aaron.weiskittel@umit.maine.edu (email)
  • Kenefic, U.S. Forest Service, Northern Research Station, Bradley, ME 04411, USA ORCID ID:E-mail:
  • Seymour, School of Forest Resources, University of Maine, Orono, ME 04469, USA ORCID ID:E-mail:
  • Phillips, School of Forest Resources, University of Maine, Orono, ME 04469, USA ORCID ID:E-mail:
article id 209, category Research article
Jaana Luoranen, Kyösti Konttinen, Risto Rikala. (2009). Frost hardening and risk of a second flush in Norway spruce seedlings after an early-season short-day treatment. Silva Fennica vol. 43 no. 2 article id 209. https://doi.org/10.14214/sf.209
There have been years in Finland when container seedlings of Norway spruce (Picea abies (L.) Karsten) planted in the summer have been damaged by early-autumn frosts. For August and September plantings, the seedlings can be hardened by means of short-day (SD) treatment, but little information is available about its usability for earlier plantings. We studied the effects of early-season SD treatment on the frost hardiness and risk of a second flush of Norway spruce seedlings. In three successive years, second-year seedlings were grown in a greenhouse or outdoors in the spring and early summer and then subjected to two or three-week SD treatment beginning on the second, third, or fourth week of June. We monitored the height growth cessation, bud formation, and frost hardiness of the seedlings in the nursery. All SD treatments made the height growth cease, but the risk of a second flush increased if the temperature sum was less than 300 d.d. before the beginning of the SD treatment or more than 450 d.d. between the end of the treatment and mid-August. Clearly, then, SD treatment reduced the risk of a second flush in seedlings that had been grown in a greenhouse in the spring. Early-season SD treatment increased the frost hardiness of both needles and stems for late July to early September in comparison with untreated seedlings. Later in the autumn, however, the differences disappeared. Before recommending the use of early-season SD-treated seedlings for summer planting, the method has to be tested in practical field conditions.
  • Luoranen, The Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: jaana.luoranen@metla.fi (email)
  • Konttinen, The Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Rikala, The Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
article id 206, category Research article
Qiaoying Zhang, Yunchun Zhang, Shaolin Peng, Eshetu Yirdaw, Ning Wu. (2009). Spatial structure of alpine trees in Mountain Baima Xueshan on the southeast Tibetan Plateau. Silva Fennica vol. 43 no. 2 article id 206. https://doi.org/10.14214/sf.206
Most of the trees at treeline on the Tibetan Plateau are endemic to the Plateau. Yet little is known about these species. The study focused on the population structure, spatial patterns and associations of the treeline species Abies forestii var. georgei and Juniperus saltuaria at treeline and timberline in Mountain Baima Xueshan on the southeast Tibetan Plateau. These species form monodominant communities on the north- and south-facing slopes, respectively. Stem density, DBH-distribution, distribution pattern of different tree size classes, and intraspecific spatial association between different tree size classes of both species were analyzed. Spatial structure varied between A. forestii var. georgei and J. saltuaria, and for the same species, the spatial structures were also different from timberline to treeline. Stem density, mean tree height and young individuals of A. forestii var. georgei were significantly higher than those of J. saltuaria. For the same species, they were different from timberline to treeline, i.e., stem density and mean tree height of both species became lower. Size classes of both species were mainly clustered either at treeline or at timberline but at different scales, and spatial patterns of young J. saltuaria were mainly dominated by random patterns. Clumps of trees created more favorable microenvironments in harsh environments at treeline and timberline. Most tree size classes showed positive intraspecific spatial associations, but positive associations between size classes of J. saltuaria were not as significant as those of A. forestii var. georgei. The south-facing slope was usually subjected to varying intensities of pastoralism. Livestock disturbance greatly changed the microhabitat and reduced the number of young individuals. The potential of trees to regenerate was greatly inhibited, while A. forestii var. georgei showed greater regeneration potential. Spatial structures of J. saltuaria were also modified by this kind of human impact.
  • Zhang, State Key Laboratory of Biocontrol, Sun Yat-Sen University, Guangzhou 510275, Guangdong Province, China; Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, Sichuan Province, China ORCID ID:E-mail: lsspsl@mail.sysu.edu.cn (email)
  • Zhang, Shandong Institute of Light Industry, Jinan 250353, Shandong Province, China ORCID ID:E-mail:
  • Peng, State Key Laboratory of Biocontrol, Sun Yat-Sen University, Guangzhou 510275, Guangdong Province, China ORCID ID:E-mail:
  • Yirdaw, Viikki Tropical Resources Institute (VITRI), P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Wu, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, Sichuan Province, China ORCID ID:E-mail:
article id 217, category Research article
Ville Kankaanhuhta, Timo Saksa, Heikki Smolander. (2009). Variation in the results of Norway spruce planting and Scots pine direct seeding in privately-owned forests in southern Finland. Silva Fennica vol. 43 no. 1 article id 217. https://doi.org/10.14214/sf.217
This study describes the variation in the planting results for 3-year-old Norway spruce (Picea abies (L.) Karst.) and 4-year-old Scots pine (Pinus sylvestris L.) using direct seeding in privately-owned regeneration areas in southern Finland. The study material consists of operative forest regeneration quality management inventory areas from the years 2000–2006. The effect of both the regional and the administrative levels as well as ecological factors was modelled on the basis of the hierarchy structure forestry centre, Forest Owners’ Association (= FOA), forestry professional, regeneration area and sample plot. The major part of the variation occurred at the sample plot and regeneration area level. Particular attention was paid to observation of the clustered spatial distribution of Scots pine seedlings. The FOA and forestry professional levels explained 5% of the variation in Norway spruce planting and 11% of the variation in Scots pine direct seeding. Applied forest regeneration operations, site and soil characteristics were included in the fixed effects. In the planting of Norway spruce the most important factor explaining the regeneration result was soil preparation. Mounding produced better results than patching and disc trenching. The site and soil characteristics were other important factors in the operations. The selection of direct seeding of Scots pine on too fertile, fine textured or moist sites yielded poor results.
  • Kankaanhuhta, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: ville.kankaanhuhta@metla.fi (email)
  • Saksa, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Smolander, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
article id 465, category Research article
Ken Olaf Storaunet, Jørund Rolstad, Målfrid Toeneiet, Erlend Rolstad. (2008). Effect of logging on the threatened epiphytic lichen Usnea longissima: a comparative and retrospective approach. Silva Fennica vol. 42 no. 5 article id 465. https://doi.org/10.14214/sf.465
Usnea longissima is a conspicuous circumboreal “beard lichen” draping tree canopies in moist coastal and mountainous forests. It is extirpated in many European and North-American localities, presumably due to industrial forestry and air pollution, but still has a stronghold in parts of Scandinavia and U.S. and Canadian Pacific Northwest. Using a retrospective approach, we reconstructed the stand histories in 24 plots (0.1 ha) of mature Norway spruce (Picea abies) forest stands in Lillehammer, Norway, of which 21 was selected due to the presence of U. longissima. Number of trees with U. longissima present within plots varied from 4 to 37 and number of visible thalli from 12 to 469. The detailed stand reconstructions were done by means of tree-ring analysis of 517 living trees and the size and decay stage of 1423 stumps from logging and 467 dead trees. Total harvested volume during the last 100 years ranged 100–370 m3ha–1 (representing 40–350% of the present-day standing volume), and present amount of dead wood ranged 2–87 m3ha–1 (1.0–37% of the standing volume). All stands had been selectively logged 2–4 times during the last 100 years, of which 5 stands almost to a clearcut appearance. We used a variety of present-day and historic forest structural variables, both at the scale of study plots and individual trees, to predict the occurrence and abundance of U. longissima. Although most forest stand variables failed in this respect, there were indications of a certain negative influence of the historic logging activity. Number of thalli present on trees showed a unimodal relationship to present-day tree density, indicating that medium dense forest stands are most favorable for U. longissima. We tentatively suggest that selective logging, securing lichen-rich trees, may be a viable management option to keep tree density at a moderate level in the long run, thereby enhancing growth and establishment of U. longissima.
  • Storaunet, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail: ken.storaunet@skogoglandskap.no (email)
  • Rolstad, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail:
  • Toeneiet, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail:
  • Rolstad, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail:
article id 234, category Research article
Enni Flykt, Sari Timonen, Taina Pennanen. (2008). Variation of ectomycorrhizal colonisation in Norway spruce seedlings in Finnish forest nurseries. Silva Fennica vol. 42 no. 4 article id 234. https://doi.org/10.14214/sf.234
Ectomycorrhizal (ECM) colonisation patterns and seedling growth of containerised spruce seedlings were studied in five typical Finnish forest nurseries by morphotyping and molecular characterisation. ECM colonisation degree of 1-year-old spruce seedlings was below 20% in all studied Finnish forest nurseries. In 2-year-old spruce seedlings the ECM colonisation degree was ca. 50–60% in three of the nurseries, but negligible in others. The ECM fungal species richness varied from 0.1 to 3.8 types per seedling. Altogether seven ECM morphotypes were distinguished. The clearest factors associated with ECM colonisation patterns were nitrogen and phosphorus fertilisation. Particularly fertilisation in the early stage of seedling development appeared to diminish the degree of colonisation and species richness of ECM fungi. Root/shoot ratio was positively correlated with high colonisation degree and species richness of ECM fungi. Higher fertilisation inputs in these overall fertilisation levels did not increase the size of the seedlings. According to these results moderate fertilisation levels particularly in the beginning of seedling cultivation are critical for generating higher root/shoot ratios and sufficient ECM colonisation degree of the roots.
  • Flykt, University of Helsinki, Department of Applied Chemistry and Microbiology, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Timonen, University of Helsinki, Department of Applied Chemistry and Microbiology, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Pennanen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
article id 248, category Research article
Tuula Jyske, Harri Mäkinen, Pekka Saranpää. (2008). Wood density within Norway spruce stems. Silva Fennica vol. 42 no. 3 article id 248. https://doi.org/10.14214/sf.248
We studied the variation in average wood density of annual rings, earlywood density, and latewood density in addition to ring width and latewood percentage within Norway spruce (Picea abies (L.) Karst.) stems from the pith to the bark, and from the stem base towards the stem apex. Moreover, the variation in wood density within annual rings was studied at the different heights and radial positions in the stem. The material consisted of 85 trees from central and south-eastern Finland. Variation between the annual rings accounted for 11–27% of the total variation in wood density. Only small differences (3–6%) in wood density were found between different heights in the stem. The largest (49–80%) variation in wood density was found within the annual rings. The difference in wood density between earlywood and latewood was smaller in the rings near the pith than in the outer rings. The increasing wood density from the pith outwards was related to increasing latewood density and latewood percentage, whereas the earlywood density increased only slightly from the pith outwards. In a given cambial age (i.e., given rings from the pith), the average wood density of annual rings increased with increasing stem height. In contrast, in the rings formed in the same calendar years (i.e., given rings from the bark), the average wood density of annual rings decreased with increasing stem height. The results of this study verify our knowledge of wood density variation and can further contribute to creating models to predict wood density.
  • Jyske, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: tuula.jyske@metla.fi (email)
  • Mäkinen, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
  • Saranpää, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
article id 468, category Research article
Antti Lännenpää, Tuomas Aakala, Heikki Kauhanen, Timo Kuuluvainen. (2008). Tree mortality agents in pristine Norway spruce forests in northern Fennoscandia. Silva Fennica vol. 42 no. 2 article id 468. https://doi.org/10.14214/sf.468
We examined tree mortality agents in pristine old Norway spruce (Picea abies (L.) Karst.) forests in northern Finland and northwestern Russia. The data was collected on nine 40 m   400 m transects. The primary mortality agents of recently dead trees were recorded and their frequencies were calculated. The pattern of tree growth prior to death was studied based on increment core samples and compared with the growth of healthy dominant trees. Of all recently dead trees, 72% could be associated with a primary mortality agent. In both study areas the most common primary mortality agent was a Coniophora (Mérat) DC. -genus fungi, which was found on average in 33% of trees sampled. The fungi Phellinus chrysoloma (Fr.) Don and Onnia leporina (Fr.) H. Jahn as mortality agents were more common in the Finnish area compared to the Russian area. Analysis on the growth patterns indicated weak differences between different pathogens’ influence on prior-to-death growth of trees, so that fungi rotting the whole tree decreased tree growth more rapidly than fungi rotting only the heart wood. The results demonstrated that in old Norway spruce forests of northern Fennoscandia the most common primary tree mortality agents were wood rotting fungi, which weaken the mechanical stability of tree stems until they fall due to snow or wind, which should be considered only as secondary mortality agents. It is evident that tree death in pristine forest typically results from a long-lasting process involving both biotic and abiotic factors.
  • Lännenpää, Department of Forest Ecology, University of Helsinki, Finland ORCID ID:E-mail:
  • Aakala, Department of Forest Ecology, University of Helsinki, Finland ORCID ID:E-mail: tuomas.aakala@helsinki.fi (email)
  • Kauhanen, Kolari Research Unit, Finnish Forest Research Institute, Finland ORCID ID:E-mail:
  • Kuuluvainen, Department of Forest Ecology, University of Helsinki, Finland ORCID ID:E-mail:
article id 252, category Research article
Tuomo Kalliokoski, Pekka Nygren, Risto Sievänen. (2008). Coarse root architecture of three boreal tree species growing in mixed stands. Silva Fennica vol. 42 no. 2 article id 252. https://doi.org/10.14214/sf.252
Root system architecture determines many of the vital functions of a tree, e.g. stability of anchorage and resource uptake. The shoot:root ratio is determined through the allocation of resources. Studies on below-ground architectural elements in boreal mixed forests are relatively scarce despite the fact that knowledge on below-ground interactions and allocation changes in relation to stand developmental stage and soil fertility is needed both in ecological and silvicultural research. In this study, sixty tree root systems of three different tree species, Betula pendula, Picea abies and Pinus sylvestris, were excavated in five mixed forest stands in order to quantify differences between the species and sites in terms of rooting behaviour. Root architecture differed greatly between the species, implying different solutions for the functions of root systems. Half of the P. sylvestris had developed a taproot as a response to anchorage needs, while P. abies correspondingly had pronounced secondary growth of proximal roots. Betula pendula had the most extensive root system, illustrating the greater demand of deciduous trees for water. Betula pendula was also the most sensitive to soil fertility: it favoured exploration on the poorest site, as illustrated by the high total root length, whereas on the most fertile site its strategy was to efficiently exploit soil resources through increased branching intensity. The results obtained in this study provide basic knowledge on the architectural characteristics of boreal tree root systems for use by forestry professionals and modellers.
  • Kalliokoski, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: tuomo.kalliokoski@metla.fi (email)
  • Nygren, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Sievänen, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
article id 272, category Research article
Jonas Rönnberg, Mattias Berglund, Ulf Johansson. (2007). Incidence of butt rot at final felling and at first thinning of the subsequent rotation of Norway spruce stands in south-western Sweden. Silva Fennica vol. 41 no. 4 article id 272. https://doi.org/10.14214/sf.272
The incidence of butt rot in Norway spruce stands at final felling and at first thinning of the subsequent rotation was investigated at 20 sites in south-western Sweden. There was a negative correlation between the incidence at first thinning and the basal area of decayed trees at final felling. Using incidence of decay or basal area of decayed trees to predict disease transfer between rotations is difficult and requires the inclusion of several factors, making predictions uncertain. The level of infection found at final felling in this study varied between 7 and 71.8%, indicating that the risk of spore infection transfer to the next rotation was probably quite low. Long-term experiments are required to reveal the effect of stump treatment on disease transmission between rotations.
  • Rönnberg, SLU, Southern Swedish Forest Research Centre, P.O. Box 49, SE-23053 Alnarp, Sweden ORCID ID:E-mail: jonas.ronnberg@ess.slu.se (email)
  • Berglund, SLU, Southern Swedish Forest Research Centre, P.O. Box 49, SE-23053 Alnarp, Sweden ORCID ID:E-mail:
  • Johansson, Tönnersjöheden Experimental Forest, P.O. Box 17, SE-31038 Simlångsdalen, Sweden ORCID ID:E-mail:
article id 471, category Research article
Michael Vohland, Johannes Stoffels, Christina Hau, Gebhard Schüler. (2007). Remote sensing techniques for forest parameter assessment: multispectral classification and linear spectral mixture analysis. Silva Fennica vol. 41 no. 3 article id 471. https://doi.org/10.14214/sf.471
One of the most common applications of remote sensing in forestry is the production of thematic maps, depicting e.g. tree species or stand age, by means of image classification. Nevertheless, the absolute quantification of stand variables is even more essential for forest inventories. For both issues, satellite data are attractive for their large-area and up-to-date mapping capacities. This study followed two steps, and at first a supervised parametric classification was performed for a German test site based on a radiometrically corrected Landsat-5 TM scene. There, eight forest classes were identified with an overall accuracy of 87.5%. In the following, the study focused on the estimation of one key stand variable, the stem number per hectare (SN), which was carried out for a number of Norway spruce stands that had been clearly identified in the multispectral classification. For the estimation of SN, the approach of Linear Spectral Mixture Analysis (LSMA) was found to be clearly more effective than spectral indices. LSMA is based on the premise that measured reflectances can be linearly modelled from a set of so-called endmember spectra. In this study, the endmember sets were held variable to decompose pixel values to abundances of a vegetation, a background (soil, litter, bark) and a shade fraction. Forest structure determines the visible portions of these fractions, and therefore, a multiple regression using them as predictor variables provided the best SN estimates. LSMA allows a pixel-by-pixel quantification of SN for complete satellite images. This opens the view to exploit these data for an improved calibration of large-scale multi-parameter assessment strategies (e.g. statistical modelling or the kNN method for satellite data interpretation).
  • Vohland, University of Trier, Faculty of Geography and Geosciences, Remote Sensing Department, Trier, Germany ORCID ID:E-mail:
  • Stoffels, University of Trier, Faculty of Geography and Geosciences, Remote Sensing Department, Trier, Germany ORCID ID:E-mail:
  • Hau, University of Trier, Faculty of Geography and Geosciences, Remote Sensing Department, Trier, Germany ORCID ID:E-mail:
  • Schüler, Research Institution for Forest Ecology and Forestry (FAWF), Department of Forest Growth and Silviculture, Trippstadt, Germany ORCID ID:E-mail:
article id 281, category Research article
Florence Renou-Wilson, Edward P. Farrell. (2007). The use of foliage and soil information for managing the nutrition of Sitka and Norway spruce on cutaway peatlands. Silva Fennica vol. 41 no. 3 article id 281. https://doi.org/10.14214/sf.281
This investigation focuses on the development and nutrient status of the first Sitka spruce and Norway spruce stands established on milled cutaway peatlands in Ireland in the late 1980s and early 1990s. Phosphatic fertilization at planting is critical for the establishment of trees on cutaway peatlands but may not be sufficient to see the stands close canopy. Results from this study indicate the likely demand for P and N fertilizer during the rotation of these plantations. During the ten-year-study period (1994–2004), the nutrient status of both Norway and Sitka spruce stands deteriorated with the passage of time. Twenty-seven out of the twenty-eight examined stands became P deficient before 10 years old and half of the plots were N deficient within 13 to 15 years. Sitka spruce stands became N and P deficient earlier than Norway spruce. Regardless of species, tree stands growing on Sphagnum peat entered the critical N deficiency threshold sooner and were all severely deficient by 2004 compared to 22% of the trees growing on Phragmites peat. The effects of aerial re-fertilization were also site specific and although P deficiency was cured, the trees were likely to suffer from nutrient imbalance (N and Cu especially). These results demand a change of standard fertilization practices, which should be related more specifically to peat type and species requirements. Peat type identification and foliar analysis monitoring should become standard management tools while the long-term continuous monitoring of these new forests would be very valuable throughout their first rotation.
  • Renou-Wilson, University College Dublin, Dublin, Ireland ORCID ID:E-mail:
  • Farrell, University College Dublin, Dublin, Ireland ORCID ID:E-mail:
article id 306, category Research article
Niina Tanskanen, Hannu Ilvesniemi. (2007). Spatial distribution of fine roots at ploughed Norway spruce forest sites. Silva Fennica vol. 41 no. 1 article id 306. https://doi.org/10.14214/sf.306
We examined the spatial distribution of fine roots at two forest sites that were ploughed 20 (site K1) and 33 years (site K2) before sampling and planted with Norway spruce (Picea abies (L.) Karst.) seedlings. Soil core samples were taken from the tilt and beneath the tilt, the furrow and the intermediate undisturbed soil to a depth of 0.4 m for fine root biomass, length and necromass determinations. Norway spruce fine roots were found throughout the ploughed forest sites. The fine roots were, however, unevenly distributed: the fine root biomass was highest in the tilt (624 and 452 g m–2 at sites K1 and K2, respectively) and lowest in the undisturbed soil at site K1 (79 g m–2) and in the furrow at site K2 (145 g m–2). The estimated average fine root biomass at the ploughed forest sites (268 and 248 g m–2 at sites K1 and K2, respectively) was, however, similar to those presented in other studies concerning sites that had not been ploughed. In the tilt, a substantial proportion of the fine roots was in the inverted mineral soil horizons and in the new organic horizon above the tilt. Consistent with the fine root biomass findings, the Norway spruce necromass was highest in the tilt but the vertical distribution of the dead roots was different: the necromass was highest in the buried OBT horizon. The results of this study suggest that at the ploughed forest sites, a substantial part of Norway spruce nutrient and water uptake occured in the tilt during the first 20 or 33 years after plantation.
  • Tanskanen, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: niina.tanskanen@helsinki.fi (email)
  • Ilvesniemi, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
article id 334, category Research article
Jouni Siipilehto. (2006). Linear prediction application for modelling the relationships between a large number of stand characteristics of Norway spruce stands. Silva Fennica vol. 40 no. 3 article id 334. https://doi.org/10.14214/sf.334
The aim was to produce models for a large number of stand characteristics of Norway spruce dominated stands. A total of 227 national forest inventory based permanent stand plots, dominated by Norway spruce (Picea abies), were used in modelling eight stand variables as a function of the stand mean biological age and site characteristics. The basic models were able to characterize the average development of the modelled stand variables, but resulted in a relatively high RMSE. Basal area (G) and stem number (N) were the most inaccurate, having a RMSE of 34–41%, while that of mean diameter and height characteristics varied between 16–20%. The expectations and error variances of the basic models were calibrated with known stand variables using linear prediction theory. The best linear unbiased predictor (BLUP) with a single stand variable used for calibration proved to be ineffective for unknown G and N, but relatively effective for the unknown mean characteristics. However, calibration with one sum and one mean characteristic proved to be effective, and additional calibration variables enhanced the precision only marginally. The BLUP method provided a flexible approach when characterizing the relationships between a large number of stand variables, thus enabling multiple use of these models because they were not fixed to a specific inventory system.
  • Siipilehto, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: jouni.siipilehto@metla.fi (email)
article id 353, category Research article
Jaakko Repola, Hannu Hökkä, Timo Penttilä. (2006). Thinning intensity and growth of mixed spruce-birch stands on drained peatlands in Finland. Silva Fennica vol. 40 no. 1 article id 353. https://doi.org/10.14214/sf.353
The impacts of thinning at various intensities on the growth and mortality of mixed spruce-birch stands were investigated in thinning experiments on spruce swamps in northern and south-eastern Finland. At the time of establishment, three of the stands had recently reached the first commercial thinning stage and four were more advanced. The monitoring period was mainly 15 years, and the thinning intensity varied from heavy thinning (ca. 46 per cent of the basal area removed) to no thinning. Basal area removals of light and moderate thinning were ca. 22% and 39%, respectively. Unthinned plots had the highest volume increment. Light and moderate thinning slightly decreased the 15-year volume increment by, on an average, 1% and 8%, respectively. Heavy thinning led to a greater reduction (22%) in volume increment. The growth response to thinning intensity was evident as a higher relative volume and mean diameter increment of the living trees with decreasing stand density. Part of the volume increment on the unthinned plots was lost through natural mortality. Even light thinning significantly decreased natural mortality.
  • Repola, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: jaakko.repola@metla.fi (email)
  • Hökkä, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Penttilä, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
article id 372, category Research article
Ulf Sikström. (2005). Pre-harvest soil acidification, liming or N fertilization did not significantly affect the survival and growth of young Norway spruce. Silva Fennica vol. 39 no. 3 article id 372. https://doi.org/10.14214/sf.372
Acidification, liming, and N fertilization affect a number of soil properties. Such changes may have an impact on forest regeneration and yield. The aim of this study was to investigate the survival and growth of Picea abies (L.) Karst. planted on plots that had been acidified (in 12 annual treatments totalling 600 or 1200 kg S ha–1 in the form of elemental sulphur), limed (12 x 500 = 6000 kg lime ha–1 in the form of CaCO3) or N-fertilized (3 x 200 = 600 kg N ha–1 in the form of urea) prior to harvest. Trees growing on plots treated with a combination of the N plus the lower S application were also tested. None of the treatments, applied in three replicate stands, significantly influenced either survival or growth of Picea abies trees during the first 11 growing seasons after planting.
  • Sikström, SkogForsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail: ulf.sikstrom@skogforsk.se (email)
article id 388, category Research article
Jacob Edlund, Mats Warensjö. (2005). Repeatability in automatic sorting of curved Norway spruce saw logs. Silva Fennica vol. 39 no. 2 article id 388. https://doi.org/10.14214/sf.388
Sawn wood from curved logs is prone to have cross grain and contain compression wood, both of which affect the dimensional stability. Different types of curvature can, however, have different effects on both the sawing process and board quality, which is why a standard measure of bow height alone is not enough to sort logs or set the log quality. The aim of this study was to evaluate the repeatability when sorting curved saw logs using a 3D log scanner. In the study, 56 logs were categorized into five different curvature types and four different degrees of curvature severity. The logs were run through a Rema 3D log scanner four times, and the external geometry was recorded. From the geometry data, variables describing log shapes were calculated and used to develop models using linear discriminant analysis, which was used to classify the logs according to curvature type. The accuracy and repeatability were evaluated for the classifications with Cohen’s simple Kappa coefficient. The results of this study showed that it is possible to sort logs by curve type using a 3D log scanner, although sorting by curve type was largely dependent on curve severity. The repeatability test determined that the chance of a curved log being graded identically two consecutive times was 0.40, measured as kappa.
  • Edlund, SLU, Department of Forest Products and Markets, P.O. Box 7060, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: jacob.edlund@spm.slu.se (email)
  • Warensjö, SLU, Department of Forest Products and Markets, P.O. Box 7060, SE-750 07 Uppsala, Sweden ORCID ID:E-mail:
article id 393, category Research article
Seppo Rouvinen, Anne Rautiainen, Jari Kouki. (2005). A relation between historical forest use and current dead woody material in a boreal protected old-growth forest in Finland. Silva Fennica vol. 39 no. 1 article id 393. https://doi.org/10.14214/sf.393
Assessing the human impact on the naturalness and vegetation characteristics of protected areas is one of the key issues when designing forest conservation networks in Fennoscandia. We studied the small-scale, detailed relationship between forest utilization history and the current availability of dead woody material in a protected old-growth forest area in North Karelia, eastern Finland. From the study area of 32.4 ha, all the stumps (diameter ≥ 5 cm and height < 1.3 m, classified as natural, man-made and of undetermined origin) were measured using 25 x 25 m sub-plots. Standing and fallen dead trees (dbh ≥ 5 cm) were measured on 50 x 50 m plots in an area of 7.8 ha. The average number of stumps was 130 per ha, and over half of the stumps were classified as man-made. However, the historical documents since the 1910s showed no logging in the area: some of the largest man-made stumps probably originated from an earlier time, but most of those stumps were made considerably later. The variation in the total number of stumps (per ha) was great (range 0–560/ha, 0–16 m2/ha), with no clear clustering in space. However, clustering of man-made stumps was detected. The average volume of pooled standing and fallen trees was 84 m3/ha, with a range of 37–146 m3/ha. The other noticeable man-made disturbance besides logging was notching of aspens, which has a scatteredly significant influence on the amount of dead trees. In conclusion, the protected old-growth forest was not as a whole in a natural state but showed different degrees of human impact from virtually untouched patches to quite heavily managed patches. The results suggest that the number of man-made stumps may be a relatively quick and easy method of assessing the naturalness of woody biomass structure in the Fennoscandian boreal forests.
  • Rouvinen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: seppo.rouvinen@joensuu.fi (email)
  • Rautiainen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Kouki, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
article id 410, category Research article
Jouni Siipilehto, Juha Siitonen. (2004). Degree of previous cutting in explaining the differences in diameter distributions between mature managed and natural Norway spruce forests. Silva Fennica vol. 38 no. 4 article id 410. https://doi.org/10.14214/sf.410
The degree of naturalness was assessed in 37 mature (stand age 80 198 yrs) Norway spruce dominated stands located in southern Finland by measuring the number (0 610 ha–1) and basal area (0 33 m2 ha–1) of cut stumps. The Johnson’s SB distribution was fitted for living spruce trees to describe the dbh-frequency and basal area-dbh distributions. Regression models were constructed for predicting the parameters of the SB distribution using traditional stand parameters (median diameter, basal area, stem number) and the cut stump variables (number, basal area). Stump variables improved the models and enabled to explain the differences in diameter distributions between stands with varying intensity of past cutting. Model for basal area-dbh distribution was more accurate than dbh-frequency model in terms of regression statistics, but less accurate in terms of generated stand variables. The number and basal area of cut stumps seem to be useful and simple measures of stand naturalness which have potential uses in stand modelling and biodiversity-oriented forestry planning.
  • Siipilehto, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: jouni.siipilehto@metla.fi (email)
  • Siitonen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: juha.siitonen@metla.fi
article id 405, category Research article
Timo Saksa. (2004). Regeneration process from seed crop to saplings – a case study in uneven-aged Norway spruce-dominated stands in southern Finland. Silva Fennica vol. 38 no. 4 article id 405. https://doi.org/10.14214/sf.405
The dynamics of spruce regeneration, from seed crop to saplings, was studied based on five permanent plots in uneven-aged, spruce-dominated, boreal forest stands, cut with single-tree selection in the beginning of the 1990’s. The annual fluctuation of the spruce seed crop was very similar in uneven-aged and even-aged stands. The correlation between seed crop and number of germinants was significant; but stem number, basal area or volume of the stand did not influence on seedling emergence. The effects of good seed crops were seen as peaks or an increase in the number of germinants and smallest seedlings. The mean number of ‘stabilised’ spruce seedlings (height 11 cm to 130 cm) varied from 6000 ha–1 to over 25 000 spruce seedlings ha–1 from one monitoring plot to another. On a monitoring plot the number of ‘stabilised’ spruce seedlings was stable over time. Neither stand basal area nor stand volume influenced the number of ‘stabilised’ spruce seedlings, but the height of these seedlings was higher on subplots with lower stand volume and smaller basal area. In this study the monitoring period, 5–10 years, was too short to obtain reliable figures for ingrowth, i.e. the transition of seedlings to the sapling stage (h > 130 cm). The adjusted mean ingrowth was 26 stems ha–1 year–1.
  • Saksa, Finnish Forest Research Institute, Suonenjoki Research Station, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: timo.saksa@metla.fi (email)
article id 483, category Research article
Staffan Jacobson. (2003). Addition of stabilized wood ashes to Swedish coniferous stands on mineral soils - effects on stem growth and needle nutrient concentrations. Silva Fennica vol. 37 no. 4 article id 483. https://doi.org/10.14214/sf.483
Increasing use of forest fuels for energy production is generating increasing quantities of wood ash. A common understanding is that this ash should be spread in forests to counteract soil acidification and potential future nutrient deficiencies, and thus help sustain long-term forest productivity. A series of seven field experiments was established in Sweden in 1988–1995 to study the stem growth and needle nutrient concentrations of 30–60-year-old Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands on mineral soil after additions of wood ash in different doses or a combination of wood ash and N. The results showed that the most pronounced growth responses occurred when N was added, either alone or in combination with wood ash. The stem growth responses to additions of wood ash without N were small and variable, and not statistically significant at any of the studied experimental sites. However, there were indications that the addition of wood ash may increase stem-wood growth on fertile sites and decrease it on less fertile sites. In the short term, the addition of wood ash tended to increase the needle nutrient concentrations of most analyzed elements, except for N, but this could not be correlated to responses in stem growth.
  • Jacobson, The Forestry Research Institute of Sweden, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail: staffan.jacobson@skogforsk.se (email)
article id 520, category Research article
Rüdiger Grote. (2002). Foliage and branch biomass estimation of coniferous and deciduous tree species. Silva Fennica vol. 36 no. 4 article id 520. https://doi.org/10.14214/sf.520
Under changing environmental conditions, biomass development on the tree and the stand level may differ from today, regardless if the induced change is due to a shift in the general climate properties or to forest management. Under these conditions, tree biomass can not be derived from tables based on former investigations but has to be defined from particular biomass investigations, which generally calculate tree and stand biomass from sample branches using allometric relationships. Therefore, sample measurements on harvested trees are needed. In this paper, foliage and branch biomass estimation for 6 Norway spruces (Picea abies) and 6 beeches (Fagus sylvatica) harvested in a 56-year-old mixed stand in southern Germany is presented. Different allometric models are investigated to derive branch biomass from branch dimension for both species. The equations that are based on branch length, foliated branch fraction, and branch diameter are used for tree and stand level estimates. However, the variation within the 6 trees of each species was too large for a reliable calculation of stand biomass, especially in case of beech branch wood. Furthermore, the necessity of allometric relations and their applicability in individual-tree models is discussed, and the importance of suitable branch- and tree selection is underlined.
  • Grote, TU München, Chair of Forest Yield Science, Am Hochanger 13, D-85354 Freising, Germany ORCID ID:E-mail: ruediger.grote@lrz.tu-muenchen.de (email)
article id 519, category Research article
Magnus Lindén, Gudmund Vollbrecht. (2002). Sensitivity of Picea abies to butt rot in pure stands and in mixed stands with Pinus sylvestris in southern Sweden. Silva Fennica vol. 36 no. 4 article id 519. https://doi.org/10.14214/sf.519
Repeatedly sampled data from permanent experimental plots in southern Sweden were used to model butt rot development in Norway spruce growing in pure stands and in mixed stands with Scots pine. The data come from 29 sites with pure spruce, altogether 100 plots, and from 15 sites of mixed spruce and pine, altogether 22 plots. A logistic model provided the best fit to the data. The study material revealed that in mixed stands the proportion of spruce trees with butt rot is lower than in pure Norway spruce stands. The difference in the incidence of butt rot cannot be explained by silviculture or windthrow since both factors are accounted for in the study. The most significant effect on butt rot development in Norway spruce by an admixture of Scots pine, was found when the Scots pine admixture was 50%. In order to reduce the incidence of butt rot in Norway spruce, the study material indicate that there is little to be gained by increasing the Scots pine admixture to much more than 50%.
  • Lindén, Southern Swedish Forest Research Centre c/o Asa Experimental Forest, SLU, S-360 30 Lammhult, Sweden ORCID ID:E-mail: magnus.linden@ess.slu.se (email)
  • Vollbrecht, Southern Swedish Forest Research Centre c/o Asa Experimental Forest, SLU, S-360 30 Lammhult, Sweden ORCID ID:E-mail:
article id 542, category Research article
Håkan Lindström. (2002). Intra-tree models of juvenile wood in Norway spruce as an input to simulation software. Silva Fennica vol. 36 no. 2 article id 542. https://doi.org/10.14214/sf.542
Juvenile wood found in the first 5–25 growth rings of a conifer has a structure and properties that differ from mature wood. Juvenile wood is therefore said to influence processing and the end-use of sawn products. Consequently, models describing the juvenile wood content, within and between trees, could be useful in improving the utilisation and value of wood as an industrial raw material. The objective of the present study was to develop juvenile wood models, based on Norway spruce trees, which could be used within a model system for conversion simulation studies. Nineteen stands of Norway spruce (Picea abies [L.] Karst.) were selected throughout Sweden. Based on DBH, two small, two medium, and two large diameter timber trees were taken from each stand. DBH varied between 180–470 mm, tree height between 17–34 m, and total age between 51–152 years. Each selected tree was cross-cut into logs; discs were prepared from the large end of each log and from the top end of the top log. Image analysis was used to determine growth ring development on sampled discs. Using tree and growth variables, the juvenile core radius and the logarithmic value of juvenile wood percentage were modelled. The two models had an R2Adj of 0.71 and 0.88 respectively.
  • Lindström, University of Canterbury, School of Forestry, Private Bag 4800, Christchurch, New Zealand ORCID ID:E-mail: lindstromhakan@netscape.net (email)
article id 540, category Research article
Finn H. Brække, Nagwa Salih. (2002). Reliability of foliar analyses of Norway spruce stands in a Nordic gradient. Silva Fennica vol. 36 no. 2 article id 540. https://doi.org/10.14214/sf.540
Norway spruce stands at eleven sites in Finland, Norway and Sweden have been studied under various climates, atmospheric deposition of N and S and fertilisation regimes. Nitrogen was growth restricting at eight inland sites, while P was growth restricting at three coastal sites. Liming and N fertilisation caused serious B deficiency on some of the inland sites. It is likely that liming affects uptake of B, whereas N fertilisation causes a dilution due to increased growth. Application of S combined with N probably caused K deficiency at one of the sites. The reliability of foliar analyses as a method to diagnose nutrient status and the likely changes after nutrient input to spruce forests in the Nordic countries, are discussed. The CR- and the DOP-method are evaluated for diagnostic purposes. Both methods seem to give reliable conclusions even if the CR-method often produces more specific results. Interpretation based on both current and one year old foliage improved the diagnostic prognoses. The accuracy of diagnosis also relies on knowledge and ability of the interpreter. Based on the results it is reason to be cautious about recommendations of single element fertilisations, e.g. with N alone, because the demand of other elements beyond available pools frequently occurs. Forest trees in the boreal region are probably well adapted to N deficiency, which means that they can handle the physiological consequences rather well, while deficiencies of other elements usually are more detrimental to growth vigour and stress related diseases.
  • Brække, Department of Forest Sciences, Agricultural University of Norway (AUN), P.O. Box 5044, N-1432 Ås, Norway ORCID ID:E-mail: finn.braekke@isf.nlh.no (email)
  • Salih, Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences (SLU), P.O. Box 7072, S-750 07 Uppsala, Sweden ORCID ID:E-mail:
article id 557, category Research article
Tuomo Wallenius, Timo Kuuluvainen, Raimo Heikkilä, Tapio Lindholm. (2002). Spatial tree age structure and fire history in two old-growth forests in eastern Fennoscandia. Silva Fennica vol. 36 no. 1 article id 557. https://doi.org/10.14214/sf.557
Two near natural old-growth forests, one dominated by Picea abies and the other by Pinus sylvestris, were studied for their fire history, and spatial patterns of trees and tree ages. The spatial tree age structure and the disturbance history of the forests were examined by drawing age class maps based on mapped and aged trees and by dating fires based on fire scars, and by using spatial analyses at tree scale. The tree age structures of the Picea and Pinus dominated forests were different, mainly due to differences in fire history and sensitivity of the dominant tree species to fire. Fire histories and tree age structures of both sites have probably been affected by human in the ancient past. However, in the Picea dominated site, the fires had been severe, killing most of the trees, whereas in the Pinus dominated site the severity of fires had been more variable, leaving some Pinus and even Picea trees alive. In the Pinus dominated site, the tree age distribution was multimodal, consisting of two Pinus cohorts, which were established after fires and a later Picea regeneration. The Picea dominated site was composed of four patches of different disturbance history. In the oldest patch, the tree age distribution was unimodal, with no distinct cohorts, while a single cohort that regenerated after severe fire disturbances dominated the three other patches. In both sites the overall spatial patterns of living and dead trees were random and the proportion of spatially autocorrelated variance of tree age was low. This means that trees of different age grew more or less mixed in the forest without forming spatially distinct regeneration patches, even in the oldest patch of Picea dominated Liimatanvaara, well over 200 years after a fire. The results show that detail knowledge of disturbance history is essential for understanding the development of tree age structures and their spatial patterns.
  • Wallenius, Department of Ecology and Systematics, University of Helsinki, P.O. Box 65, FIN-00014, Helsinki, Finland ORCID ID:E-mail: tuomo.wallenius@helsinki.fi (email)
  • Kuuluvainen, Department of Forest Ecology, University of Helsinki, P.O. Box 27, FIN-00014, Helsinki, Finland ORCID ID:E-mail:
  • Heikkilä, Research Centre of Friendship Park, Tönölä, FIN-88900 Kuhmo, Finland ORCID ID:E-mail:
  • Lindholm, Finnish Environment Institute, Nature and Land Use Division, P.O. Box 140, FIN-00251 Helsinki, Finland ORCID ID:E-mail:
article id 577, category Research article
Jouni Siipilehto. (2001). Effect of weed control with fibre mulches and herbicides on the initial development of spruce, birch and aspen seedlings on abandoned farmland. Silva Fennica vol. 35 no. 4 article id 577. https://doi.org/10.14214/sf.577
Post-planting weed control methods on abandoned farmland were studied in three field trials in southern Finland using a completely randomized design with four treatments and 30 to 40 replications. Mulches of 60 x 60 cm [sheet mulch – strips of plane waste and plastic fibre, newspaper – waste paper slurry, wood chips, pure wood fibre slurry], herbicides [i.e. glyphosate or terbuthylazine alone or mixed and dichlobenile applied to 1 m2 spots] and hoeing treatments were compared to an untreated control plot. The study material consisted of two-year-old containerized aspen (Populus tremula L.), silver birch (Betula pendula (L.) Roth) and Norway spruce (Picea abies (L.) Karst.) seedlings planted in spring 1996. The ground vegetation was dominated by Elymys repens, Deschampsia cespitosa, Cirsium arvense and Epilobium angustifolium. Monitoring of the trials over a 3-year period showed a moderate effect of weed control, which varied according to the method used and by the crop species. Significant growth responses were found with herbicide in spruce, wood chips in spruce and birch and with sheet mulch in aspen seedlings. Sheet mulch also encouraged vole nesting thus increasing damages. Generally, slurry mulches proved to be insufficiently durable. Mulching had a clear insulating effect, which may increase the risk of winter drought.
  • Siipilehto, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail: jouni.siipilehto@metla.fi (email)
article id 590, category Research article
Anna Saarsalmi, Eino Mälkönen, Sirpa Piirainen. (2001). Effects of wood ash fertilization on forest soil chemical properties. Silva Fennica vol. 35 no. 3 article id 590. https://doi.org/10.14214/sf.590
The effects of wood ash fertilization on soil chemical properties were studied in three young Scots pine (Pinus sylvestris L.) plantations and a Norway spruce (Picea abies (L.) Karst.) plantation with different site fertility in southern Finland. The dose of 3 t ha–1 of loose wood ash was applied to 4 replicate plots (25 x 25 m) at each experiment. Humus layer and mineral soil samples were taken before the treatment and 7 and 16 years after wood ash application. Results showed that neutralization as well as fertilization effects of wood ash on forest soil were of long duration. An ash-induced pH increase of 0.6–1.0 pH units and exchangeable acidity (EA) decrease of 58–83% were detected in the humus layer 16 years after wood ash application. The decrease in acidity was most pronounced on the Calluna site with initially the lowest pH and highest EA. In the mineral soil the increase in pH was observed later than in the humus layer. After 16 years, the mineral soil pH was increased (0.2–0.3 pH units) on the Vaccinium and Myrtillus sites. A corresponding and in most cases a significant increase in the extractable Ca and Mg concentrations was detected in both the humus layer and in the mineral soil. Wood ash significantly increased the effective cation exchange capacity (CECe) and base saturation (BS) but decreased the concentration of exchangeable Al in both soil layers on all the sites. No response of N availability to wood ash application could be found.
  • Saarsalmi, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail: anna.saarsalmi@metla.fi (email)
  • Mälkönen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail:
  • Piirainen, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail:
article id 602, category Research article
Teijo Nikkanen. (2001). Reproductive phenology in a Norway spruce seed orchard. Silva Fennica vol. 35 no. 1 article id 602. https://doi.org/10.14214/sf.602
Reproductive phenology was studied in a Norway spruce seed orchard, located in southern Finland (62°13’N, 25°24’E), consisting of 67 clones from northern Finland (64°–67°N). Timing of flowering was determined on the basis of data recorded by a pollen catch meter during 1984–1995, and visual observations made on grafts in 1989, 1992, 1993 and 1995. The genetic and environmental factors affecting female and male phenology, and reproductive synchronisation were studied. The between-year variation in the timing of flowering was more than three weeks. However, when it was defined on the basis of the effective temperature sum, the variation was smaller. No phenological reproductive isolation was found between the seed orchard and surrounding natural forests. The duration of the receptive period of the seed orchard varied from 5 to 8 days, and anthesis determined on the basis of airborne pollen from 5 to 10 days. The receptive period started about one day earlier than anthesis, except in one abnormally warm flowering period when female and male flowering started simultaneously. In general, the flowering periods of the different clones overlapped. The clonal differences in the phenology of receptivity were in most cases statistically significant, but in pollen shedding they were not. The broad-sense heritability estimates were higher for female than for male phenology. Environmental factors, conversely, had a stronger effect on male phenology. A wide graft spacing and a graft position that favoured solar radiation on the lower parts of the crown promoted early pollen shedding and, subsequently, better reproductive synchronisation between female and male flowering.
  • Nikkanen, Finnish Forest Research Institute, Punkaharju Research Station, FIN-58451 Punkaharju, Finland ORCID ID:E-mail: teijo.nikkanen@metla.fi (email)
article id 622, category Research article
Håkan Lindström. (2000). Intra-tree models of basic density in Norway spruce as an input to simulation software. Silva Fennica vol. 34 no. 4 article id 622. https://doi.org/10.14214/sf.622
Basic density is said to influence aspects of conversion, properties, and end-use of forest products. Consequently, it is argued that accurate models of basic density variation, within and between trees, could be used to improve the utilisation of wood as an industrial raw material. The objective of the present study was to develop basic density models based on Norway spruce trees, that could be used within a model system for conversion simulation studies. Nineteen stands of Norway spruce (Picea abies (L.) Karst.) were selected throughout Sweden. Based on dbh, two small, two moderate, and two large timber trees were taken from each stand. Dbh varied between 180–470 mm, tree height between 17–34 m, and total age between 51–152 years. Each selected tree was cross-cut into logs; discs were prepared from the butt end of each log and from the top end of the top log. Computed tomography scanning and image analysis were used to determine basic density and growth ring development on sampled discs. Basic density development in 20-mm segments from pith outwards was modelled in models based on ring width, tree and growth condition data. The resulting models had an adjusted R2 of 0.37–0.51 and a RMSE of 37–41 kg/m3.
  • Lindström, University of Canterbury, School of Forestry, Private Bag 4800, Christchurch, New Zealand ORCID ID:E-mail: lindstromhakan@netscape.net (email)
article id 617, category Research article
Jouni Siipilehto. (2000). A comparison of two parameter prediction methods for stand structure in Finland. Silva Fennica vol. 34 no. 4 article id 617. https://doi.org/10.14214/sf.617
The objective of this paper was to predict a model for describing stand structure of tree heights (h) and diameters at breast height (dbh). The research material consisted of data collected from 64 stands of Norway spruce (Picea abies Karst.) and 91 stands of Scots pine (Pinus sylvestris L.) located in southern Finland. Both stand types contained birch (Betula pendula Roth and B. pubescent Ehrh.) admixtures. The traditional univariate approach (Model I) of using the dbh distribution (Johnson’s SB) together with a height curve (Näslund’s function) was compared against the bivariate approaches, Johnson’s SBB distribution (Model II) and Model Ie. In Model Ie within-dbh-class h-variation was included by transforming a normally distributed homogenous error of linearized Näslund’s function to concern real heights. Basal-area-weighted distributions were estimated using the maximum likelihood (ML) method. Species-specific prediction models were derived using linear regression analysis. The models were compared with Kolmogorov-Smirnov tests for marginal distributions, accuracy of stand variables and the dbh-h relationship of individual trees. The differences in the stand characteristics between the models were marginal. Model I gave a slightly better fit for spruce, but Model II was better for pine stands. The univariate Model I resulted in clearly too narrow marginal h-distribution for pine. It is recommended applying of a constrained ML method for reasonable dbh-h relationship instead of using a pure ML method when fitting the SBB model.
  • Siipilehto, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland ORCID ID:E-mail: jouni.siipilehto@metla.fi (email)
article id 626, category Research article
Teijo Nikkanen, Seppo Ruotsalainen. (2000). Variation in flowering abundance and its impact on the genetic diversity of the seed crop in a Norway spruce seed orchard. Silva Fennica vol. 34 no. 3 article id 626. https://doi.org/10.14214/sf.626
The variation in flowering abundance was studied in a Norway spruce seed orchard, located in southern Finland (62°13'N, 25°24'E), consisting of 67 clones from northern Finland (64°–67°N). The flowering variation in 1984–1996 was studied at the annual, clonal and graft level. In addition, the genetic diversity of an imaginary seed crop was estimated using a concept of status number. The between-year variation was large in both female and male flowering. Differences in flowering abundance among the clones were large and statistically significant in all the years studied. The average broad-sense heritability values for female and male flowering were 0.37 and 0.38, respectively, but varied considerably from year to year. The correlations between the flowering abundance of the clones in different years were usually positive and significant. However, the correlations for two pairs of successive good flowering years showed that the same clones usually flowered well in the first year in both pairs of years, and the other clones in the second year. The clonal differences in flowering could not be explained by geographic origin, but were more dependent on the graft size. Our results demonstrate that the variation in the ramet number, flowering abundance and pollen contamination must be included when estimating the genetic diversity of the seed crop in a seed orchard. The relative status number of the seed orchard was 84% of the number of clones when the variation in the ramet number was included. The relative status numbers after adjusting for the variation in female and male flowering were on the average 46 and 55%, respectively, and 59% when adjusting for both genders together. Pollen contamination increased the status number considerably.
  • Nikkanen, Finnish Forest Research Institute, Punkaharju Research Station, FIN-58450 Punkaharju, Finland ORCID ID:E-mail: teijo.nikkanen@metla.fi (email)
  • Ruotsalainen, Finnish Forest Research Institute, Punkaharju Research Station, FIN-58450 Punkaharju, Finland ORCID ID:E-mail:
article id 649, category Research article
Tord Johansson. (1999). Biomass production of Norway spruce (Picea abies (L.) Karst.) growing on abandoned farmland. Silva Fennica vol. 33 no. 4 article id 649. https://doi.org/10.14214/sf.649
Biomass production of forests has been studied for at least a century. Tree biomass is used in Sweden both as industrial raw material and an energy source. Few studies dealing with biomass yield from Norway spruce (Picea abies (L.) Karst.) growing on farmland are published. Practical recommendations are sparsely. The aim of this study was to construct dry weight equations for Norway spruce growing on farmland. Dry weight equations for fractions of Norway spruce trees were made. Biomass production was estimated in 32 stands of Norway spruce growing on abandoned farmland. The stands were located in Sweden at latitudes ranging from 58° to 64° N, and their total age varied from 17 to 54 years. A modified ‘mean tree technique’ was used to estimate biomass production; i.e. the tallest tree was chosen for sampling. The actual mean total dry weight above stump level for the 32 stands was 116 ton ha–1, with a range of 6.0 to 237.4 ton d.w. ha–1. When previous thinning removals were included, the mean biomass value was 127 ton ha–1 (6.0–262.8). In addition to estimating conventional dry weights of trees and tree components, basic density, specific leaf area, total surface area and leaf area index, among other measures, were estimated. Norway spruce biomass yields on plots subjected to different thinning were compared. The total harvested biomass was 75–120 ton d.w. ha–1 in heavy thinnings from below. Stands were thinned four to five times, with the first thinning at 23–27 years and the last at 51–64 years. The harvested biomass obtained in the first thinning was 18–38 ton d.w. ha–1. Total biomass production was 178–305 ton d.w. ha–1. Stands thinned from above supplied 71–130 ton d.w. ha–1 in total and 17–42 ton d.w. ha–1 in the first thinning. The total biomass supply was 221–304 ton d.w. ha–1. Unthinned stands produced a total of 155–245 ton d.w. ha–1.
  • Johansson, Swedish University of Agricultural Sciences, Department of Forest Management and Products, P.O. Box 7060, S-750 07 Uppsala, Sweden ORCID ID:E-mail: tord.johansson@sh.slu.se (email)
article id 676, category Research article
Erik Sundström. (1998). Afforestation of low-productive peatlands in Sweden – a tree species comparison. Silva Fennica vol. 32 no. 4 article id 676. https://doi.org/10.14214/sf.676
In 1970, five low-productive treeless peatlands in Sweden, ranging from latitudes 56°N to 67°N, were drained and fertilized for afforestation. The aim of the study was to determine the effect of four ditch spacings, varying from 7.5 to 60 m, and five NPK-fertilizer combinations, on the survival and growth of planted Scots pine (Pinus sylvestris), lodgepole pine (Pinus contorta), Norway spruce (Picea abies), and silver birch (Betula pendula) seedlings. The assessments were carried out 18–22 years after planting. Neither silver birch, nor Norway spruce was regarded suitable for the site type. The mortality of silver birch was almost complete, and Norway spruce did not grow well in any of the study areas, however, better than Scots pine in the north. Lodgepole pine had better height and diameter growth but also higher mortality rates than Scots pine. In the two northernmost experimental areas no response to fertilization was found. In the other three areas, the response to fertilization did not differ between species. Phosphorus was the most effective of the added fertilizer elements, whereas nitrogen showed no positive effect. Broadcast fertilizer application, with three times higher amount of fertilizer per ha gave the same growth response as spot application.
  • Sundström, Swedish University of Agricultural Sciences, Dept. of Silviculture, S-901 83 Umeå, Sweden ORCID ID:E-mail: erik.sundstrom@ssko.slu.se (email)
article id 672, category Research article
Rimvydas Vasiliauskas, Jan Stenlid. (1998). Spread of Stereum sanguinolentum vegetative compatibility groups within a stand and within stems of Picea abies. Silva Fennica vol. 32 no. 4 article id 672. https://doi.org/10.14214/sf.672
A total of 57 naturally established Stereum sanguinolentum isolates was obtained from artificially wounded Picea abies stems in a forest area of 2 ha in Lithuania. Somatic incompatibility tests revealed 27 vegetative compatibility groups (VCGs) that contained 1–10 isolates. There was no spatial clustering of S. sanguinolentum VCGs within the forest area. The extent of S. sanguinolentum decay was analysed in 48 P. abies stems, 9–26 cm in diameter at breast height. Within 7 years of wounding, the length of S. sanguinolentum decay column in stems was 107–415 cm (291.5 ± 77.3 cm on average), lateral spread of the fungus at the butt was 38–307 cm2 (142.3 ± 66.8 cm2) and decayed proportion of the stem cross-section at the wound site (the butt) was 3–84% (36.8 ± 19.7%). In average, S. sanguinolentum VCG that infected 10 trees exhibited more slow growth inside the stem than VCGs that infected only one tree, and vertical growth varied to a greater extent within this VCG than among different VCGs. Correlation between stem diameter and vertical spread of S. sanguinolentum was not significant (r = –0.103). Despite uniformity of debarked area on all stems 7 years ago (300 cm2), open wound sizes on individual trees at the time of study were between 97–355 cm2 (215.1 ± 59.2 cm2) indicating large differences in wound healing capacity.
  • Vasiliauskas, Department of Plant Protection, Lithuanian University of Agriculture, LT-4324 Kaunas, Lithuania ORCID ID:E-mail:
  • Stenlid, Department of Forest Mycology & Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, S-750 07 Uppsala, Sweden ORCID ID:E-mail:

Category: Research note

article id 1346, category Research note
Āris Jansons, Roberts Matisons, Oskars Krišāns, Baiba Džeriņa, Mārtiņš Zeps. (2016). Effect of initial fertilization on 34-year increment and wood properties of Norway spruce in Latvia. Silva Fennica vol. 50 no. 1 article id 1346. https://doi.org/10.14214/sf.1346
Highlights: The initial fertilization increased the productivity of Picea abies increasing stem volume by 17% at the age of 34 years; The tree-ring width was affected for up to15 years; The fertilization did not affect mean tree-ring density, although the latewood density was increased.

Initial fertilisation, when the fertilizer is supplied during the plantation, is applied to improve the competitive ability of the seedlings and hence to increase their growth and productivity; however, fertilization could also alter wood properties and timber quality. In this study, the dimensions and tree-ring parameters – width, proportion of latewood, maximum and mean density, mean earlywood and latewood density – of initially fertilized (by 14, 6 and 11 g of N, P and K per seedling, respectively) Norway spruce (Picea abies Karst.) growing in an experimental plantation in Kalsnava, Latvia (temperate climate region) were assessed. The fertilization significantly increased the dimensions of trees in long-term (ca. 17% increase of stemwood volume). The analysis of tree-ring width suggested that the duration of the effect was ca. 15 years. The maximum and latewood density were higher for the fertilized trees only in a few years. The mean and earlywood density of tree-rings were mainly similar for both treatments. Altogether, considering the one-time application of a limited amount of fertilizer, such treatment had notable and lasting effect on Norway spruce.

  • Jansons, LSRFI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: aris.jansons@silava.lv
  • Matisons, LSRFI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: robism@inbox.lv (email)
  • Krišāns, LSRFI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: oskars.krisans@silava.lv
  • Džeriņa, LSRFI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: baiba.dzerina@silava.lv
  • Zeps, LSRFI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: martins.zeps@silava.lv
article id 1330, category Research note
Hanne K. Sjølie, Hans Asbjørn Kårstad Sørlie, Bjørn Tveite, Birger Solberg. (2015). The performance of two Swedish N fertilization functions evaluated on data from Norwegian fertilization experiments. Silva Fennica vol. 49 no. 4 article id 1330. https://doi.org/10.14214/sf.1330
Highlights: The performance of two predictive Swedish fertilization growth response functions was assessed on data from Norwegian fertilization experiments; One function performed well on the full dataset, but overpredicted the growth response in spruce plots and underpredicted in pine plots; The second function performed well in pine stands, but overestimated the growth response in spruce and in total.

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

  • Sjølie, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway ORCID ID:E-mail: hanne.sjolie@nmbu.no (email)
  • Sørlie, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway ORCID ID:E-mail: hans.asbjorn.sorlie@slf.dep.no
  • Tveite, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail: bjorn.tveite@skogoglandskap.no
  • Solberg, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway ORCID ID:E-mail: birger.solberg@nmbu.no
article id 915, category Research note
Kalle Kärhä. (2012). Comparison of two stump-lifting heads in final felling Norway spruce stand. Silva Fennica vol. 46 no. 4 article id 915. https://doi.org/10.14214/sf.915
The use of stump and root wood chips has increased very rapidly in the 21st century in Finland: in the year 2000, the total consumption of stump wood chips for energy generation was 10 GWh, while in 2010 it was approximately 2 TWh. Metsäteho Oy and TTS Research evaluated two stump-lifting devices for the lifting of Norway spruce (Picea abies) stumps. The productivity and costs of stump lifting were determined. There was one base machine with one operator in the time study. When lifting stumps with a diameter of 30 cm, the effective hour productivity of stump lifting was 11.2 m3 solid over bark (sob)/E0 (4.8 tonD/E0) without site preparation using a Väkevä Stump Processor, and when lifting spruce stumps with a diameter of 40 cm, the productivity was 14.9 m3 sob/E0 (6.5 tonD/E0). When the site preparation (mounding) was integrated into lifting work, the stump-lifting productivity decreased 21–27%. The stump-lifting productivity of the other lifting head (Järvinen) was lower than that of the Väkevä Stump Processor. Some development suggestions for the Järvinen lifting head were presented and discussed. The cost calculations showed that stump-lifting costs are extremely high when stump diameter is less than 20 cm. Therefore, the study recommended a change in the current stump-harvesting guidelines of Finland: The study suggested that all the stumps with a diameter less than 20 cm should be left on the harvesting site.
  • Kärhä, Stora Enso Wood Supply Finland, Talvikkitie 40 C, FI-01300 Vantaa, Finland ORCID ID:E-mail: kalle.karha@storaenso.com (email)
article id 118, category Research note
Audrius Menkis, Remigijus Bakys, Vaidotas Lygis, Rimvydas Vasaitis. (2011). Mycorrhization, establishment and growth of outplanted Picea abies seedlings produced under different cultivation systems. Silva Fennica vol. 45 no. 2 article id 118. https://doi.org/10.14214/sf.118
In forest nurseries seedlings are commonly produced using different cultivation systems which may have a profound effect on the extent of root colonisation by ectomycorrhizal (ECM) fungi and, consequently, on subsequent performance of the outplanted seedlings under field conditions. In this study, we compare effects of bare-root and containerised cultivation systems on mycorrhization, establishment and growth of nursery-produced Picea abies. One hectare experimental plantation was established on poor fertility sandy site. In total, 1250 seedlings of each treatment were planted in rows as ten individual replicates. The results of this study showed that production of P. abies seedlings using containerised system can yield abundant ECM colonisation of seedling roots and significantly improve seedling survival in the field. Some reduction in height increment may occur during the first years as a possible cost for support of ECMs. Study demonstrated that selection of proper cultivation system might result in similar or higher mycorrhization and survival rates of outplanted seedlings than achieved by expensive and laborious artificial mycorrhization.
  • Menkis, Department of Forest Mycology and Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: audrius.menkis@slu.se (email)
  • Bakys, Department of Forest Mycology and Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-750 07 Uppsala, Sweden ORCID ID:E-mail:
  • Lygis, Laboratory of Phytopathogenic Microorganisms, Institute of Botany at the Nature Research Centre, Vilnius, Lithuania ORCID ID:E-mail:
  • Vasaitis, Department of Forest Mycology and Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-750 07 Uppsala, Sweden ORCID ID:E-mail:
article id 403, category Research note
Timo Saksa, Juha Heiskanen, Jari Miina, Jaakko Tuomola, Taneli Kolström. (2005). Multilevel modelling of height growth in young Norway spruce plantations in southern Finland. Silva Fennica vol. 39 no. 1 article id 403. https://doi.org/10.14214/sf.403
Height development of Norway spruce (Picea abies (L.) Karst.) transplants was studied on 22 sites prepared by disc trenching or mounding. At the age of 4–9 years the plantations were surveyed using a multistage sampling design. For every planted spruce on a plot, the past annual height increments were measured as far into the past as possible. Multilevel mixed linear modelling was used to analyse the variation in growth at different levels (year, stand, cluster, plot, tree) and the effects of climatic and site characteristics on height growth. The within-plantation variation in height growth was higher on mounded sites than on disc-trenched sites. The mean temperature and the precipitation sum of the summer months affected height growth positively. Soil characteristics measured from undisturbed soil did not explain the height growth of seedlings on mounded sites, whereas on disc-trenched sites, the depth of the organic layer and the soil temperature had a positive effect and the depth of the eluvial horizon a negative effect. The modelling approach used proved to be a useful method for examining the sources of variation in development of young plantations.
  • Saksa, The Finnish Forest Institute, Suonenjoki Research Station, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Heiskanen, The Finnish Forest Institute, Suonenjoki Research Station, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Miina, The Finnish Forest Institute, Joensuu Research Centre, P. O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Tuomola, The University of Joensuu, Mekrijärvi Research Station, FI-82900 Ilomantsi, Finland ORCID ID:E-mail:
  • Kolström, The University of Joensuu, Mekrijärvi Research Station, FI-82900 Ilomantsi, Finland ORCID ID:E-mail:
article id 421, category Research note
Pekka Helenius, Jaana Luoranen, Risto Rikala. (2004). Effect of thawing duration and temperature on field performance of frozen-stored Norway spruce container seedlings. Silva Fennica vol. 38 no. 3 article id 421. https://doi.org/10.14214/sf.421
Increasing use of frozen storage in nurseries at northern latitudes calls for thawing methods that are safe, economical and easy to apply on a large scale. The easiest and most economical method would be to thaw seedlings in the same boxes they were stored in. However, doing this safely requires more knowledge about how long and at what temperatures seedlings should or can be kept in the boxes without reducing field performance. In this study, 1-yr-old frozen-stored Norway spruce (Picea abies (L.) Karst.) container seedlings were thawed for 4, 8 or 16 days at 4 or 12 °C in cardboard boxes before planting on a reforestation site and on experimental field in mid-June. Some seedlings were also planted on these locations after thawing for only 7 hours at 12 °C in order to separate frozen root plugs. We found some evidence that planting seedlings after short thawing periods (7 hours at 12 °C and 4 days at 4 °C), under which conditions the root plugs remain completely or partly frozen, has a negative effect on field performance of Norway spruce seedlings. Thawing over a 4-8 day period in cardboard boxes at ca. 12 °C appears to ensure complete thawing of the root plugs and unaffected field performance, but is short enough to prevent the growth of mould.
  • Helenius, Finnish Forest Research Institute, Suonenjoki Research Station, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: pekka.helenius@metla.fi (email)
  • Luoranen, Finnish Forest Research Institute, Suonenjoki Research Station, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Rikala, Finnish Forest Research Institute, Suonenjoki Research Station, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:

Category: Article

article id 7178, category Article
Matti Keltikangas, Pekka Tiililä. (1968). Koivun ja kuusen istutuksen keskinäinen edullisuusjärjestys käenkaali-mustikkatyypin metsämailla. Acta Forestalia Fennica vol. 82 no. 5 article id 7178. https://doi.org/10.14214/aff.7178
English title: The economic sequence of silver birch (Betula pendula) and Norway spruce (Picea abies) when planting Oxalis-Myrtillus type forest land.

The present study proposes to calculate the economic sequence of two of Finland’s three main tree species, Norway spruce (Picea abies (L.) H. Karst.) and silver birch (Betula pendula Roth) when planted on Oxalias-Myrtillus type sites where both species are equally suitable, on biological grounds. In addition, the accuracy and applicability of the present Finnish yield tables to an economic comparison is tested. Benefit/cost ratio was selected as criterion of profitableness. All future net incomes and costs were discounted into the planting time and added together. The ratio between the discounted net revenues and the discounted investment costs (later called profit ratio) was the criterion. There is no reliable method to forecast the future wood prices, therefore two price ratios, birch veneer timber to spruce pulpwood and birch cordwood to spruce pulpwood, were chosen as free variables. The economic sequence of the tree species was determined as the function of these variables.

The main conclusions are, first, that under the present price ratios spruce appears to be the better choice for the forest owner, and the most promising policy for changing the situation seems to decrease the production costs of plants in birch nurseries. Second, the present Finnish yield tables are not consistent or accurate enough to enable any sufficiently reliable economic comparisons of tree species in artificial regeneration. The possible error of difference between two rather uncertain estimates is big. More work is needed to construct a uniform system of yield tables covering all main tree species, all site types, all macro climate conditions and all types of regeneration.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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  • Yli-Vakkuri, ORCID ID:E-mail:
article id 7490, category Article
Valter Keltikangas. (1959). Suomalaisista seinäsammaltyypeistä ja niiden asemasta Cajanderin luokitusjärjestelmässä. Acta Forestalia Fennica vol. 69 no. 2 article id 7490. https://doi.org/10.14214/aff.7490
English title: Finnish feather-moss types and their position in Cajander’s forest site classification .

Since Finnish professor A.K. Cajander published his theory on forest types, there have been discussion and contradictory studies on certain forest types. This paper is a litterature review on the thick-moss type in Northern Finland and its parallel types in Kainuu and Southern Finland. First, the principles of Cajander’s theory on forest types is described and discussed. It is concluded that Cajander has described forest site types as their common, genuine variants. Borderline variants have been excluded from the description. 

Second, the North Finnish thick-moss type (Hylocomnium-Myrtillus type, HMT) and its position in Cajander’s system is discussed. Concepts of this forest type have varied considerably, and it has been argued that the type does not fit Cajander’s system very well, as it arises as a result of the invasion of other forest types by Norway spruce (Picea abies (L.) Karst.) with consequent degeneration of the site.  

The writer concludes findings of the results of the previous studies about MHT and its relations to the Myrtillus type. Cajander in his system included the thick-moss type in the moist upland forests as a type whose vegetation is less exacting than that of the Myrtillus type. This position seems to be the right one. Some factors point out the moist nature of HMT: the ability of Norway spruce to compete, a relatively high persipitation, the humidity of the climate in general and the rather poor water percolation capacity of the moraine soil. The HMT sites are relatively poor. It is stated that the opinion that the thick-moss type is secondary state of development of the Myrtillus type has no plant sociological, ecological, mensurational or silvicultural foundation. The type is probably Finland's most dynamic forest type, but in the natural forest its dynamics are confined to such changes as are permitted within the same forest type. HMT must be described as three series of plant association types, which differ from another to some extent. 

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

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

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

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

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

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

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  • Heikurainen, ORCID ID:E-mail:
article id 7473, category Article
Kustaa Kallio. (1957). Käenkaali-mustikkatyypin kuusikoiden kehityksestä Suomen lounaisosassa. Acta Forestalia Fennica vol. 66 no. 3 article id 7473. https://doi.org/10.14214/aff.7473
English title: On the development of spruce forests of the Oxalis-Myrtillus site type in the south-west of Finland.

In this investigation was studied 1) Volume growth and yield of timber in managed Norway spruce (Picea abies (L.) Karst.) forests under different rotations. 2) Value growth, net forest income and soil expectation value of managed forests under different rotations, and 3) The rotations of spruce forests managed on different rotation principles. The data was collected from Oxalis-Myrtillus type forests in South-West Finland.

Two developmental series of stands were constructed for the research, one of which were of better sites than the other. Sample plots were pure, even-aged spruce stands in well-managed forests. The stands had been thinned from below. The age varied from 25-30 years to the age of final cutting.

According to the study, in the artificially regenerated spruce stands the highest mean annual volume growth, 9.7 m3/ha, and also the highest net annual income of 14,50 Finnish marks/ha (calculated from average stumpages) was reached in rotation of 70 years. In the other managed spruce forests a mean annual volume growth of 6.6-8.8 m3/ha and the net annual income of 10,500-14,500 Finnish marks/ha were reached in the rotation of 70-100 years. The rotation for the maximum mean annual volume growth varied in the different series between 67-92 years. The maximum mean annual forest rent was only achieved in series B in a rotation of about 100 years, and in a naturally normal stand in a rotation of about 120 years. The intensity of thinnings and silviculture had a greater effect on value growth and on net income than on volume growth.

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  • Kallio, ORCID ID:E-mail:
article id 7467, category Article
Matti Nuorteva. (1956). Hakkuiden vaikutuksesta kaarnakuoriaisten esiintymiseen eräällä metsäalueella Etelä-Hämeessä. Acta Forestalia Fennica vol. 65 no. 4 article id 7467. https://doi.org/10.14214/aff.7467
English title: Effect of fellings on bark beetle population in a forest area in Southern Finland.

Bark beetle populations live usually in a balance in natural forests, and outbreaks occur seldom. The populations have been found to increase in managed forests. Fellings affect the structure of the forests, which influence the living conditions of the insects, and produce material for reproduction. In this study the occurrence of bark beetles was studied in a forest area in Etelä-Häme in Southern Finland using line plot survey.

The forests in the area were Norway spruce (Picea abies L. Karst.) dominated. Over third of the 140 sample plots studied were in forests which had never been cut or it was over ten years to the last logging. Bark beetles of 26 different species were found in 66 of the sample plots. The most common species was six-toothed spruce bark beetle (Pityogenes chalcographus L.), which was due to the abundance of growth material suitable for the species in the area. New species in the area were common double-eyed spruce bark beetle (Polygraphus polygraphus L.), Pityophthorus micrographus L., and Dryocetes-beetle (either Dryocetes autographus or D. hectographus). The fellings increased the occurrence of beetles. The amount and quality of logging residue affected the abundance of the insects.

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

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

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

The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.
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  • Rummukainen, ORCID ID:E-mail:
article id 7402, category Article
Gustaf Sirén. (1950). Alikasvoskuusten biologiaa. Acta Forestalia Fennica vol. 58 no. 2 article id 7402. https://doi.org/10.14214/aff.7402
English title: On the biology of undergrown Norway spruce.

Norway spruce (Picea abies (L.) Karst.) invading sites is common in Finland. The species tends to establish itself as undergrowth, and takes over when it gets space to grow. To determine whether the undergrowth is suitable as the new generation requires knowledge on the biology of spruce undergrowth. One of the issues is determining the age of the stunted trees. In this investigation, 100 undergrown spruce trees, their crown and their root systems were studied. A method was developed to determine the age of the trees.

The root system of all trees in Vaccinium sites and of stunted trees in Myrtillius sites were superficial. The root systems of older spruces were purely of adventitious origin. The longer the period of stunting growth, the younger is the root system. In addition to acropetal and general adventitious ramification there is often adventitious branching of the roots of pathological causes. Mortality among the long roots is frequent.

A stunted tree has not the same ability as a viable tree to make use of already existing branches for building assimilating surface. When comparing trees with equally large assimilating surface, a stunted tree had greater sum of roots compared to a viable tree. The root system of a stunted undergrown spruce was very superficial compared with the other trees.

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

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

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

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

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  • Kalela, ORCID ID:E-mail:
article id 7389, category Article
P. S. Tikka. (1947). Perä-Pohjolan kuusikoiden laadusta. Acta Forestalia Fennica vol. 55 no. 1 article id 7389. https://doi.org/10.14214/aff.7389
English title: Quality of Norway spruce stands in Peräpohjola in Northern Finland.

The different kinds of injuries in Norway spruce (Picea abies (L.) Karst.) stands was studied in 52 sample plots in Peräpohjola in the northernmost Finland. The age classes of the stands varied from 100 years to over 220 years. Most of the stands were unevenaged, as is usual in the area.

In the younger age classes (121-160 years) majority of the trees were of normal quality or had smaller injuries in all forest types. In age classes over 160 years the trees of merchantable quality decreased markedly in all forest types. The quality of the trees decreases with the age especially because of butt rot, braking of trees and crooks, forks and heart and top decay caused by the injuries. To ensure future quality it would be important that the stand is healthy from the beginning. When old spruce stands of the area are in large extent diseased by the root rot, it is questionable if they can be regenerated using natural regeneration. The spruce stands of the area are also relatively branchy. This could be prevented by growing the young stands dense. Changing the dominant tree species to Scots pine (Pinus sylvestris L.) in the dry upland forest sites could be a way to improve the quality of the forests in the area.

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  • Tikka, ORCID ID:E-mail:
article id 7383, category Article
Esko Kangas. (1946). Kuusikoiden kuivumisesta metsätuho- ja metsänhoidollisena kysymyksenä. Acta Forestalia Fennica vol. 52 no. 5 article id 7383. https://doi.org/10.14214/aff.7383
English title: Drying of Norway spruce stands as forest damage and forest management issues in Finland.

Observatons of drying of Norway spruce (Picea abies (L.) Karst.) stands increased in 1930s in Southern Finland. The aim of the study was to analyse the advance and causes of drying. The work was begun in 1930s before the Second World War, and the damages caused to the forests by the war was used as supplemental observations in the study. A special method, drying analysis, was developed to study the process. It was used both in cases of insect and fungal diseases in the four research areas in Raivola and Ruotsinkylä. In addition, 7 observation areas were studied.

Several causes for drying of the trees were observed in the Norway spruce stands. These included European spruce bark beetle (Dendroctonus micans), root rot (Heterobasidion annosum), pine weevils (Pissodes sp.), bark beetles and honey fungus (Armillaria mellea).

The role of primary and secondary causes for drying, resistance of the trees and the drying process are discussed. Finally, the influence of forest management in drying process is analysed. Forests in natural state can be considered to be in an ideal balance. On the other hand, forest management can be used to maintain the vitality and resistance of the forests. Drying of Norway spruce stands can be taken into consideration when the stands are managed.

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  • Kangas, ORCID ID:E-mail:
article id 7377, category Article
S. E. Multamäki. (1942). Kuusen taimien paleltuminen ja sen vaikutus ojitettujen soiden metsittymiseen. Acta Forestalia Fennica vol. 51 no. 1 article id 7377. https://doi.org/10.14214/aff.7377
English title: Frost injuries of Norway spruce seedlings and their effect on afforestation of drained peatlands .

The aim of the investigation was to study natural regeneration of Norway spruce (Picea abies (L.) Karst.) in drained peatlands and frost injuries in seedlings, and to compare microclimates of the regeneration areas. The experiments included peatlands in Satakunta in Western Finland. Restocking of the areas with seedlings and their survival was followed in 1935-40 at sample plots that were mainly 1 are large.

Susceptibility to freezing was shown to be dependent on the stage of development of the shoots. Shoots that have just begun to grow contain little water, and withstand better freezing temperatures than shoots in later stages of growth. Damages to the seedlings were observed when the temperatures decreased to -2.8–-4.3 °C. The most severe damage to a seedling was caused by the death of the leading shoot by spring frost.

Norway spruce regenerates easily on moist peatlands, but peatlands with dry surface tend to have little or no seedlings. The species regenerated better in marshy sites than correspondingly fertile mineral soil sites. However, it needs shelter to avoid frost damage. On clear cut spruce swamp the undergrowth spruce seedlings that were left in the site got severe frost damage. If the site had birch (Betula sp.) coppice or undergrowth, spruce seedlings survived in their shelter depending on the height and density of the birch trees. To be effective, the protective forest should have relatively even crown cover. Young spruce seedlings could grow well even under relatively dense birch stand.

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  • Multamäki, ORCID ID:E-mail:
article id 7376, category Article
O. J. Lukkala. (1942). Sateen mittauksia erilaisissa metsiköissä. Acta Forestalia Fennica vol. 50 no. 23 article id 7376. https://doi.org/10.14214/aff.7376
English title: Measurements of rainfall in different kinds of forests in Finland.

The tree canopy adsorbs part of the rainfall falling on a forest, therefore only part of it reaches the soil. This report presents results concerning interception of precipitation and groundwater level in forests of varying canopy cover. The study belongs to a larger survey on afforestation of drained treeless bogs. The rainfall was measured daily in the open fields and in the adjacent forests. The forests, mainly Norway spruce (Picea abies (L.) Karst.) dominated, were divided by the canopy cover into five classes from over dense to sparsely stocked.

The results show that in a dense, tall Norway spruce stand, light rainfall can almost entirely be adsorbed by the canopy. The heavier the rainfall, the larger proportion of it reaches the ground. Only 30% of a 5 mm rainfall reaches the ground, while 80% of a 20 mm rainfall reaches the ground. Interception of precipitation decreases gradually when the density of the forest decreases. Canopy of Scots pine (Pinus sylvestris L.) and birch (Betula sp.) stands of corresponding density adsorb less rainfall than Norway spruce canopy. Groundwater level was higher in treeless areas than in areas covered with forest. Widescale clear cuttings should, therefore, be considered carefully in forest areas that are prone to become peaty.

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

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

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

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

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

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

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  • Aaltonen, ORCID ID:E-mail:
article id 7346, category Article
Th. Wegelius. (1939). The presence and properties of knots in finnish spruce : investigations concerning the origin and characteristics of branch and knot wood in finnish spruce with particular consideration given to the raw material needs of the paper industry. Acta Forestalia Fennica vol. 48 no. 1 article id 7346. https://doi.org/10.14214/aff.7346

The most important characteristics for the quality of round timber is knottiness. Knots decrease the strength of the wood in sawn goods. Knots in pulpwood obstruct the production process of ground pulp and lower the quality. A qualitative classification of saw logs has been suggested, and the abundance of knots could also be used to determine the quality of pulpwood. In this study, visual observations on the preparation of pulpwood in pulp mill were made to observe the quality of the wood. Samples of the wood was collected, and they were divided in five quality classes. To study the influence of age, forest site type and stand on knots, 140 sample trees of Norway spruce (Picea abies (L.) H. Karst.) were analyzed. The article includes detailed analysis of the abundance and position of knots in the stems of spruce, anatomical structure of the knots, microscopic structure of the fibers, and mechanical properties of the branch and knot wood.

  • Wegelius, ORCID ID:E-mail:
article id 7343, category Article
S. E. Multamäki. (1939). Kuusen kylvöstä ja istutuksesta metsitettävillä soilla. Acta Forestalia Fennica vol. 47 no. 3 article id 7343. https://doi.org/10.14214/aff.7343
English title: Sowing and planting of Norway spruce in drained peatlands in Finland.

The drained peatlands regenerate usually well, and artificial regeneration by sowing or planting has been rare. Field trials of Norway spruce (Picea abies (L.) H. Karst.) were established in northern Satakunta in Western Finland in three drained peatlands in 1934. Sowing trials of Norway spruce consisted of patch and broadcast sowed sample sites in treeless bogs and under protective forest. The seedlings of spruce were planted either under protective forest or in treeless peatland.

The results show that artificial regeneration of Norway spruce succeeds best under protective forest. The best tree species for upper storey is Betula sp. which grows fast and controls growth of ground vegetation. The peat is relatively decomposed on those peatlands that are suitable for spruce, and breaking of the surface of the peat is not recommended. In the sowing trials, breaking of the upper layer of the peat caused frost heaving, cracking of the dried surface and sticking of mud in the seedlings in the patch sown sample site. The shoot and root growth of seedlings of the broadcast sown site was better than seedlings of the patch sown site. The planted spruce seedlings seemed to be more susceptible for spring frost than the seedlings in the sown site. The plants of seed origin succeeded in general better than the planted seedlings.

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

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

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

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  • Sarvas, ORCID ID:E-mail:
article id 7330, category Article
Erkki K. Kalela. (1936). Tutkimuksia Itä-Suomen kuusi-harmaaleppä-sekametsiköiden kehityksestä. Acta Forestalia Fennica vol. 44 no. 2 article id 7330. https://doi.org/10.14214/aff.7330
English title: Studies on the development of mixed forest of Norway spruce and grey alder in Eastern Finland.

Shifting cultivation, practiced earlier in Finland, was beneficial for grey alder (Alnus incana (L.) Moench). It can produce seeds early and the early growth of the seedlings is fast. Areas where shifting cultivation was intensive, the areas next to the fields were pure alder stands, next circle was Betula sp. dominated, beyond that could be found Scots pine (Pinus sylvestris L.), and finally Norway spruce (Picea abies (L.) H. Karst.). When shifting cultivation ended, Norway spruce became more common. Many young mixed stands had Norway spruce undergrowth and alder overgrowth. The aim of the study was to find out how the stands develop to spruce dominated stands, and how they should be managed.

The density of spruce undergrowth affects the further development of both spruce and alder. The number of alder stems decreases the faster the denser the spruce undergrowth is. Alder overgrowth slow down the early diameter and height growth of spruce compared to pure stands. Also the diameter and height growth of alder remains smaller in mixed stands. The basal area of spruce develops slowly in the beginning, increases significantly by the age of 30, and surpasses the growth of pure spruce stands in Oxalis-Myrtillus site type. Thus, Norway spruce do not suffer from growing in the undergrowth. In the first years, fast growing alder seedlings limits growth of ground vegetation and protects spruce seedlings from frost.  Later thinning or removal of alder benefits spruce growth. The density of spruce undergrowth decides how much alder can be leaved in the stand. If the spruce undergrowth is thin, more alder can be left in the stand.

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

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

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

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  • Aaltonen, ORCID ID:E-mail:
article id 7317, category Article
Erkki Laitakari. (1935). Tutkimuksia metsikön ja kasvupaikan vaikutuksesta kuusen rungon kelpoisuuteen. Acta Forestalia Fennica vol. 41 no. 4 article id 7317. https://doi.org/10.14214/aff.7317
English title: Studies on the influence of stand and forest site type on the quality of Norway spruce stem.

Healthy, straight, more or less free from branches and slowly tapering stems are good raw material for woodworking industry. The aim of the study was to investigate, from the stand point of forest management, the influence of stand and forest site type on the technical quality of the stems. Sample plots were measured in Norway spruce (Picea abies (L.) H. Karst.) stands in Eastern Finland. Norway spruce growing in a stand with closed crowns developed thin branches and self-pruned, if the stand was dense in the early stages. The decisive time for the stand is, therefore, when it is at seedling stage and young stand. The stems are more branchy if the stand has been planted. The adequate planting density is discussed based on earlier studies. The sufficient density seems to be achieved when the spacing is at maximum two meters. When the stems are branchless up to four meters, thinning of spruce stand does not affect knottiness or stem form. A sparsely stocked, knotty young stand does not produce good-quality timber even if the stand is later dense. Selective thinning from above can be used to improve the quality of the wood.

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  • Laitakari, ORCID ID:E-mail:
article id 7316, category Article
Martti Hertz. (1935). Kuusen juuriston ensi kehityksestä. Acta Forestalia Fennica vol. 41 no. 3 article id 7316. https://doi.org/10.14214/aff.7316
English title: The early development of Norway spruce root system.
English keywords: main root; forest site; seedlings

The development roots of Norway spruce (Picea abies (L.) H. Karst.) seedlings was studied in sample seedlings grown in different kinds of sites. In the early stage, the seedling roots grow primarily length. The main root is usually long. If the growth of the root is hindered, the tip of the root dies, and the root system growing from the original root collar remains relatively small; in these cases, the secondary root system becomes more important. In unfavourable conditions the root branches can early on replace the main root. The main root of a germling seems to be less able to seek for free growing space than the main and side roots of older seedlings. When the growth of the root is blocked by some kind of obstacle, it does not often hinder the growth of the seedling. The type of soil influences strongly how the root system grows. In good soil and in humus the root system is regular and richly branched, while in clay and coarse sand the root system was small. Spahgnum moss was good substrate for seedlings, Dicranum undulatum moss little less good, while the seedlings grew poorly on Pleurozium Schreberi.

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

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

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  • Backman, ORCID ID:E-mail:
article id 7294, category Article
Martti Hertz. (1934). Tutkimuksia karjan vaikutuksesta hakkausalojen kasvillisuuteen. Acta Forestalia Fennica vol. 40 no. 17 article id 7294. https://doi.org/10.14214/aff.7294
English title: Studies on influence of grazing on the vegetation of cutting areas.

The aim of the study was to determine the effect of grazing of the cutting areas to the ground vegetation and regeneration of spruce. The cutting areas could be divided into two kinds of areas based on the vegetation. Hillocks were drier and poorer than other parts of the cutting areas. Their vegetation did suffer less from grazing than the other parts of the cutting areas. The shade-loving plant species decreased, but as the poorer sites have less edible plants, cattle caused less damage than in the better sites. The even spaces between the hillocks had both positive and negative changes. Cattle transport seeds, tile and fertilize the soil, promote paludification, and decrease competition by the primary species like large grasses. This is beneficial to new species. Grazing is directed to large grass species like Calamagrostis. Those species that cattle reject, become more abundant. Stamping damages especially shallow rooted species and perennial species, like Norway spruce (Picea abies (L.) H. Karst.). Larger tree seedlings may get injuries in the stem.

The PDF includes a summary in German.

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

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

The PDF includes a summary in German.

  • Cajander, ORCID ID:E-mail:
article id 7256, category Article
V. Pöntynen. (1929). Tutkimuksia kuusen esiintymisestä alikasvoksina Raja-Karjalan valtionmailla. Acta Forestalia Fennica vol. 35 no. 1 article id 7256. https://doi.org/10.14214/aff.7256
English title: Studies on Norway spruce undergrowth in state forests in Karelia.

The abundance of Norway spruce (Picae abies (L.) H. Karst.) undergrowth is common for the state forests in Karelia near the Russian border, in Finland. In the survey, the occurrence of the undergrowth was studied. The article includes a review on the ownership of the forest, forest soils in the area, and the state of forests in the area. Scots pine (Pinus sylvestris L.) is the dominative species in 67%, Norway spruce in 27% and Betula sp. 6% of the state forests. Only 2% of the forests are 1‒20 years of age. Stands in the age group of 61‒80 years are the most common (25%). Norway spruce undergrowth is most abundant in the municipality of Salmi. The forests are typically moist forest site types or grass-herb site types. If the stands are allowed to develop naturally, even the Vaccinium sites become Norway spruce dominated. Spruce undergrowth is formed seldom under a spruce forest unless the stand is thin or has openings. Because Norway spruce is often rare in the mineral soil sites, the undergrowth is often regenerated from seeds that spread from spruce swamps. Earlier practiced shifting cultivation and its frequent fires prevented regeneration of spruce undergrowth. Similarly, the common felling method used, clear felling in strips, does not promote spruce undergrowth. Consequently, their occurrence is likely to decrease in the future.

The PDF includes a summary in German.

  • Pöntynen, 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 5633, category Article
Seppo Kaunisto, Tytti Sarjala. (1997). Critical needle potassium concentrations indicated by diamine putrescine in Norway spruce growing on peat soils. Silva Fennica vol. 31 no. 4 article id 5633. https://doi.org/10.14214/sf.a8535

Dormant needles from 129 Norway spruce (Picea abies (L.) H. Karst.) trees from the 2nd and 3rd topmost whorls were collected from spruce stands locating fairly close to each other. Tree height varied from 8 to 25 metres. Trees with and without visual potassium deficiency symptoms in needles were selected and analysed for nitrogen, phosphorus, potassium, magnesium, boron, copper, zinc, and 3 free polyamines putrescine, spermine and spermidine.

The concentrations of all the analysed nutrients ranged from deficient to satisfactory levels. Free putrescine, spermidine and spermine concentrations in the current needles had a wide variation between the trees. Spermidine had a positive and spermine a negative correlation with potassium. Putrescine had a strong negative correlation with potassium with statistically significant increase in putrescine starting at potassium concentrations below 5.4 mg/g dry weight. The regression between putrescine and potassium changed from a linear to a non-linear form at the potassium concentration of 4.2–4.6 mg/g dry weight representing a severe K deficiency limit. The corresponding K/P ratio was 2.6–2.7. Extremely low phosphorus concentrations (P < 1.0 mg/g) lowered putrescine concentrations, but otherwise the relationships between putrescine, spermidine or spermine and potassium concentrations were unaffected by tree nutrition. At adequate potassium levels the putrescine concentrations were only slightly lower in trees taller than 20 metres than in trees of 8–16 metres height. The results show that the needle putrescine concentration can be used quite reliably for describing potassium nutrition of Norway spruce in varying nutritional and tree size conditions.

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

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

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

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

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

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

  • Maltamo, ORCID ID:E-mail:
article id 5566, category Article
Reijo Penttilä, Heikki Kotiranta. (1996). Short-term effects of prescribed burning on wood-rotting fungi. Silva Fennica vol. 30 no. 4 article id 5566. https://doi.org/10.14214/sf.a8501

The prefire fungal flora (polypores and corticoid fungi) of 284 dead trees, mainly fallen trunks of Norway spruce (Picea abies (L.) H. Karst.), was studied in 1991 in an old, spruce-dominated mesic forest in Southern Finland. Species diversity of the prefire fungal flora was very high, including a high proportion of locally rare species and four threatened polypore species in Finland.

In 1992 part of the study area (7.3 ha) was clear-cut and a 1.7 ha forest stand in the centre of study area was left standing with a tree volume of 150 m3/ha, and later on (June 1st) in the same year the whole area was burned. Burning was very efficient and all trees in the forest stand were dead one year after the fire. Also, the ground layer burned almost completely.

In 1993 the fungal flora of the 284 sample trees was studied again. Most of the trees had burned strongly and the fungal species diversity and the evenness in community structure had decreased considerably as compared with the prefire community. Species turnover was also great, especially in corticoid fungi. Greatest losses in the species numbers occurred in moderately and strongly decayed trees, in coniferous trees and in very strongly burned trees. Fungal flora of non-decayed and slightly decayed trees, deciduous trees and slightly burned trees seemed to have survived the fire quite well, and in these groups the species numbers had increased slightly as compared with the prefire community.

Fungal species suffering from fire (anthracophobe species) were mainly growing in moderately and strongly decayed trees before the fire, whereas species favoured by fire (anthracophile species) were growing in less decayed trees. No fruitbodies of threatened polypores or other "old-forest species" of polypores were found again after fire. Some very common and effective wood-rotting fungi (e.g. Fomitopsis pinicola, Fomes fomentarius, Antrodia serialis) survived the fire quite well (anthracoxene species). Species favoured by fire were mainly ruderal species which can utilize new, competition-free resources created by fire, and species that have their optima in dry and open places also outside forest-fire areas. Some rarities, e.g. Phanerochaete raduloides and Physisporinus rivulosus, were favoured by fire.

  • Penttilä, ORCID ID:E-mail:
  • Kotiranta, ORCID ID:E-mail:
article id 5598, category Article
Timo Kuuluvainen, Kari Leinonen, Markku Nygren, Antti Penttinen. (1996). Statistical opportunities for comparing stand structural heterogeneity in managed and primeval forests: an example from boreal spruce forest in southern Finland. Silva Fennica vol. 30 no. 2–3 article id 5598. https://doi.org/10.14214/sf.a9243

The horizontal and vertical stand structure of living trees was examined in a managed and in a primeval Norway spruce-dominated forest in Southern Finland. Tree size distributions (DBHs, tree height) were compared using frequency histograms. The vertical distribution of tree heights was illustrated as tree height plots and quantified as the tree height diversity (THD) using the Shannon-Weaver formula. The horizontal spatial pattern of trees was described with stem maps and quantified with Ripley's K-function. The spatial autocorrelation of tree sizes was examined with semivariogram analysis. In the managed forest the DBH and height distributions of trees were bimodal, indicating a two-layered vertical structure with a single dominant tree layer and abundant regeneration in the understory. The primeval forest had a much higher total number of trees which were rather evenly distributed in different diameter and tree height classes. The K-function summaries for trees taller than 15 m indicated that the primeval stand was close to complete random pattern. The managed stand was regular at small distances (up to 4 m). The semivariograms of tree sizes (DBH tree height) showed that the managed forest had a clear spatial dependence in tree sizes up to inter-tree distances of about 12 meters. In contrast, the primeval spruce forest had a variance peak at very short inter-tree distances (< 1 m) and only weak spatial autocorrelation at short inter-tree distances (1–5 m). Excluding the understory trees (h < 15 m) from the analysis drastically changed the spatial structure of the forest as revealed by semivariograms. ln general, the structure of the primeval forest was both horizontally and vertically more variable and heterogeneous compared to the managed forest. The applicability of the used methods in describing fine-scale forest structure i discussed.

  • Kuuluvainen, ORCID ID:E-mail:
  • Leinonen, ORCID ID:E-mail:
  • Nygren, ORCID ID:E-mail:
  • Penttinen, ORCID ID:E-mail:
article id 5595, category Article
R.A. Fleming. (1996). A mechanistic perspective of possible influences of climate change on defoliating insects in North America's boreal forests. Silva Fennica vol. 30 no. 2–3 article id 5595. https://doi.org/10.14214/sf.a9240

There is no doubt that tree survival, growth, and reproduction in North America's boreal forests would be directly influenced by the projected changes in climate if they occur. The indirect effects of climate change may be of even greater importance, however, because of their potential for altering the intensity, frequency, and perhaps even the very nature of the disturbance regimes which drive boreal forest dynamics. Insect defoliator populations are one of the dominating disturbance factors in North America's boreal forests and during outbreaks trees are often killed over vast forest areas. If the predicted shifts in climate occur, the damage patterns caused by insects may be considerably changed, particularly those of insects whose temporal and spatial distributions are singularly dependent on climatic factors. The ensuing uncertainties directly affect depletion forecasts, pest hazard rating procedures, and long-term planning for pest control requirements. Because the potential for wildfire often increases in stands after insect attack, uncertainties in future insect damage patterns also lead to uncertainties in fire regimes. In addition, because the rates of processes key to biogeochemical and nutrient recycling are influenced by insect damage, potential changes in damage patterns can indirectly affect ecosystem resilience and the sustainability of the multiple uses of the forest resource.

In this paper, a mechanistic perspective is developed based on available information describing how defoliating forest insects might respond to climate warming. Because of its prevalence and long history of study, the spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), is used for illustrative purposes in developing this perspective. The scenarios that follow outline the potential importance of threshold behaviour, historical conditions, phenological relationships, infrequent but extreme weather, complex feedbacks, and natural selection. The urgency of such considerations is emphasized by reference to research suggesting that climate warming may already be influencing some insect lifecycles.

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

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

  • Beuker, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Kolström, ORCID ID:E-mail:
article id 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 5577, category Article
Malgorzata Skrzypczynska. (1996). Relationship between Megastigmus suspectus Borr. size and Abies alba Mill. Seed size. Silva Fennica vol. 30 no. 1 article id 5577. https://doi.org/10.14214/sf.a9222

Investigation on the relationship between the size of the Megastigmus suspectus Borr. (Hymenoptera, Torymidae) and the size of Abies alba Mill. seeds from which those insects emerged was conducted. The examined insects (n = 46) originated from southern Poland, and were obtained from cones collected in 1993. M. suspectus thorax length was used as an index of adult insect size, because that was correlated with 8 other body measurements. In addition, the diameter of the emergence hole of this insect was measured. All data were log-transformed and analysed using regression analysis. There was no linear correlation between adult size and seed size, using either length of thorax or any of the other 8 body traits tested.

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

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

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

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

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

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

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

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

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

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

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

The PDF includes a summary in German.

  • Heikkilä, ORCID ID:E-mail:
article id 5549, category Article
Kari Leinonen, Hannu Rita. (1995). Interaction of prechilling, temperature, osmotic stress, and light in Picea abies seed germination. Silva Fennica vol. 29 no. 2 article id 5549. https://doi.org/10.14214/sf.a9200

A multi-factor experimental approach and proportional odds model were used to study interactions between five environmental factors significant to Norway spruce (Picea abies (L.) H. Karst.) seed germination: prechilling (at +4.5°C), suboptimal temperatures (+12 and +16°C), osmotically induced water stress (0.3 Mpa and 0 Mpa), prolonged white light, and short-period of far-red light. Temperature and osmotic stress interacted with one another in the germination of seeds; the effect off osmotic stress being stronger at +16°C than at +12°C. In natural conditions, this interaction may prevent germination early in the summer when soil dries and temperature increases. Prolonged white light prevented germination at low temperature and low osmotic potential. Inhibitory effect was less at higher temperatures and higher osmotic potential, as well as after prechilling. Short-period far-red light did not prevent germination of unchilled seeds in darkness. Prechilling tended to make seeds sensitive to short pulses of far-red light, an effect which depended on temperature: at +12°C the effect on germination was promotive, but at +16°C, inhibitory and partly reversible by white light. It seems that Norway spruce seeds may have adapted to germinate in canopy shade light rich in far-red. The seeds may also have evolved mechanisms to inhibit germination in prolonged light.

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

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

  • Persson, ORCID ID:E-mail:
article id 5535, category Article
Mats Hannerz. (1994). Predicting the risk of frost occurrence after budburst of Norway spruce in Sweden. Silva Fennica vol. 28 no. 4 article id 5535. https://doi.org/10.14214/sf.a9175

Temperature sums required for budburst in various Norway spruce (Picea abies (L.) H. Karst.) provenances were determined, and weather statistics were then used to predict the risk of potentially damaging frosts at 11 locations in Sweden. Frost risk was quantified as the probability of a frost occurring within 100 day-degrees (two weeks) after budburst. The examples provided show that a spruce seedling from central Sweden has to sustain almost twice as many frost occassions as a seedling from Belorussia, when planted in southern and central Sweden. The method presented here can be used for mapping early summer frost risk in Sweden and for supporting provenance transfer guidelines.

  • Hannerz, 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 5400, category Article
Kari J. Jokinen, Don J. Durzan. (1994). Properties of rescued embryonal suspensor masses of Norway spruce determined by the genotype and the environment in vitro. Silva Fennica vol. 28 no. 2 article id 5400. https://doi.org/10.14214/sf.a9165

53 genotypes of embryonal suspensor masses (ESMs) rescued from mature seeds of Norway spruce (Picea abies (L.) H. Karst.) were examined for their pattern of growth and development under standardized culture conditions in vitro. Patterns were classified according to the colour of the colonies grown in darkness, clarity of cell masses and proembryos in the mucilaginous ESM, surface boundary topology of colonies, structure of suspensors, growth rate of the ESM, and recovery of mature embryos.

Five distinctive major growth patterns were observed among ESM colonies under standardized culture conditions. The multiplication of proembryos and early embryos by cleavage and budding polyembryony was the main factor contributing to proliferation and colony growth and further determined the morphology of the colonies. Callus and teratological structures were induced from early embryos by changing the standardized culture conditions i.e. inadequate subculture, excessive dose of 2,4-D in the medium and premature exposure of the colonies to light. Results enable the selection of ESM genotypes for the predictable recovery of mature somatic embryos.

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

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

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

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

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  • Koistinen, ORCID ID:E-mail:
  • Valkonen, ORCID ID:E-mail:
article id 5497, category Article
Pertti Pulkkinen. (1993). Frost hardiness development and lignification of young Norway spruce seedlings of southern and northern Finnish origin. Silva Fennica vol. 27 no. 1 article id 5497. https://doi.org/10.14214/sf.a15658

Seedlings from four Norway spruce (Picea abies (L.) H. Karst.) stands originating from areas with effective temperature sums ranging from 710 d.d. to 1,150 d.d. were raised under artificial light and temperature treatment. After a 10-week growing period the hardening process was started by subjecting the seedlings to +8°C night temperature and +15°C day temperature, and increasing the night length by 1.5 hour/week. Hardiness was measured by means of artificial freezing treatment (-10°C or -15°C), followed by visual estimation of the degree of needle injury. The stem height, lignification and bud development were measured before the freezing treatment. The amount of injury increased the more southern the origin of the tested material was. Furthermore, the proportion of non-lignified part of the seedling stem was negatively correlated with the latitude of the provenances. The proportion of seedlings with clearly visible buds was more than 90% in the northernmost entry and less than 1% in the southernmost one. The overall correlation coefficient between the needle injuries and the proportion of non-lignified part of the stem was rather high, but varied considerably from 0.3 in the northernmost material to over 0.6 in the southern provenances. According to the results, it seems to be possible to use growth characteristics as an indicator of frost hardiness at the provenance level.
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  • Pulkkinen, ORCID ID:E-mail:
article id 5463, category Article
Öje Danell. (1991). Survey of past, current and future Swedish forest tree breeding. Silva Fennica vol. 25 no. 4 article id 5463. https://doi.org/10.14214/sf.a15621

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

  • Danell, ORCID ID:E-mail:
article id 5459, category Article
Pertti Pulkkinen. (1991). Crown form and harvest increment in pendulous Norway spruce. Silva Fennica vol. 25 no. 4 article id 5459. https://doi.org/10.14214/sf.a15617

Crown characteristics and the distribution of three years’ (1986–88) biomass production of 20 pendulous Norway spruce (Picea abies f. pendula (Lawson) Sylvén) trees with heritable narrow crown and 15 normal-growned spruces (Picea abies (L.) H. Karst.) were studied in a 19-year-old mixed stand.

The form of the crown is conical in normal-crowned trees, columnar and narrow in pendulous trees. The partitioning of aboveground biomass to stems during the studied 3-year period was significantly higher in pendulous (0.281) than in normal-crowned trees (0.255) and also the ratio between growth of stemwood and growth of needle biomass during three years was higher in pendulous trees (0.67 g g-1) than in normal-crowned trees (0.52 g g-1). The needle biomass was distributed higher in the crown in pendula than in normal-crowned trees and they had a higher needle biomass/branchwood biomass ratio than normal trees. The difference in harvest increment between the two crown types are mostly due to the significantly lower branchwood biomass values in pendulous than in normal-crowned trees. The higher needle ’efficiency’ in pendulous trees is probably connected with high partitioning of needle biomass to the upper part of the crown in pendulous trees.

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  • Pulkkinen, ORCID ID:E-mail:
article id 5452, category Article
Riitta Höyhtyä, Heikki Hänninen. (1991). Effect of photon flux density on bud dormancy release in Norway spruce seedlings. Silva Fennica vol. 25 no. 3 article id 5452. https://doi.org/10.14214/sf.a15610

The effect of photon flux density on bud dormancy release in two-year-old seedlings of Norway spruce (Picea abies (L.) H. Karst.) was examined. The seedlings were first chilled for 0–21 weeks under natural conditions and then forced in a warm greenhouse either in low (15 μEm-2s-1) or in high (300 μEm-2s-1) photon flux density. Occurrence of bud burst was observed in the forcing conditions, and the observations were used for estimating the cumulative frequency distribution of the chilling requirement for growth competence. The estimated distribution had greater variance in the low photon flux density than in the high photon flux density forcing. This finding suggests that unnaturally low photon flux densities during forcing may yield overestimates of the genetic within-population variation in the chilling requirement for growth competence.

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  • Höyhtyä, ORCID ID:E-mail:
  • Hänninen, ORCID ID:E-mail:
article id 5450, category Article
Bo Långström, Claes Hellqvist. (1991). Shoot damage and growth losses following three years of Tomicus-attacks in Scots pine stands close to a timber storage site. Silva Fennica vol. 25 no. 3 article id 5450. https://doi.org/10.14214/sf.a15604

Shoot losses due to maturation feeding by pine shoot beetles (Tomicus piniperda (L.) and T. minor (Hart.), Col., Scolytidae) and subsequent growth losses were studied in Scots pine (Pinus sylvestris L.) stands growing at different distances from a timber yard, where pine timber was stored during the years 1982–84. In autumn 1985, pine trees were felled at 20, 40, 80, 500 and 1,500 m distance from the timber yard, five trees in each distance class. Trees were analysed for beetle attack, needle biomass and growth. In autumn 1988, increment cores were taken from 20 trees in each distance class.

In 1985, different damage estimates showed that beetle damage was more than 10-fold in the crowns of pine trees growing close to the timber yard as compared to less damaged trees in greater distance. Crude needle biomass estimates indicated that the trees attacked most had lost more than half of the total foliage. Following three years of attack, basal area growth decreased for 2–3 years and recovered during the subsequent 3 years, the total period of loss thus being 5–6 years. The loss in volume growth during 1983–85 was ca. 70, 40, 20 and 10% at 20, 40, 80 and 500 m distance from the beetle source, respectively, compared to the stand at 1,500. Growth losses did not occur until the number of beetle-attacks, ”pegs”, exceeded ca. 200 per tree. The highest observed growth losses occurred in trees with more than 1,000 pegs per tree.

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  • Långström, ORCID ID:E-mail:
  • Hellqvist, ORCID ID:E-mail:
article id 5449, category Article
Timo Pukkala, Taneli Kolström. (1991). Effect of spatial pattern of trees on the growth of Norway spruce stand. Silva Fennica vol. 25 no. 3 article id 5449. https://doi.org/10.14214/sf.a15603

The simulation model consists of a method to generate theoretical Norway spruce (Picea abies (L.) H. Karst.) stands, and a spatial growth model to predict the growth of these stands. The stand generation procedure first predicts the tree diameters from a few stand characteristics and from tree locations. Tree age and height are predicted using spatial models. Spatial growth models were made for both diameter growth and basal area growth. Past growth was used as a predictor in one pair of models and omitted in another pair. The stand generation method and the growth models were utilized in studying the effect of tree arrangement and thinning method on the growth of a Norway spruce stand.

The PDF includes an abstract in Finnish.

  • Pukkala, ORCID ID:E-mail:
  • Kolström, ORCID ID:E-mail:
article id 5445, category Article
Taneli Kolström. (1991). Kuusen kylvö- ja istutuskoe viljavilla kivennäismailla Pohjois-Karjalassa. Silva Fennica vol. 25 no. 2 article id 5445. https://doi.org/10.14214/sf.a15599
English title: Results from the sowing and planting experiment of Norway spruce (Picea abies) on fertile sites in North Karelia, Finland.

Different methods of sowing and planting of Norway spruce (Picea abies (L.) H. Karst.) were compared on fertile sites in North Karelia (62°20’N, 29°35’E, 85–120 m a.s.l.). The planting material were 4-year-old bare-rooted transplants, 2-year-old bare-rooted seedlings, and 2-year-old containerized seedlings raised in plastic greenhouse. The sowing methods were band sowing and shelter sowing. Ground vegetation was controlled during the first growing season mechanically or chemically, or the control was omitted totally.

Planting of spruce gave better results than sowing. After eight growing seasons there were sowed seedlings left in 30% of the sowing pots. The average height of them was 35 cm. Seedling survival was best with large bare-rooted transplants (91%). Survival of containerized seedlings was 79% and of small bare-rooted transplants 71%. The average height of large bare-rooted transplants was 131 cm, of containerized seedlings 86 cm and small bare-rooted seedlings 68 cm.

Sowing is not an advisable method for regeneration of spruce due to the small survival rate and slow initial development when ground vegetation is controlled only once. Also 2-year-old seedlings gave a satisfactory result in regeneration. Seedlings raised in greenhouse were more sensitive to frost damage than seedlings grown on open ground.

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  • Kolström, ORCID ID:E-mail:
article id 5442, category Article
Erkki Annila, Kari Heliövaara. (1991). Chemical control of cone pests in a Norway spruce seed orchard. Silva Fennica vol. 25 no. 2 article id 5442. https://doi.org/10.14214/sf.a15596

The effect of three pesticides containing either dimethoate (0.5% a.i.), permitrin (0.5%) or triadimephon (0.5%) on the cone pests and flowering biology of Norway spruce (Picea abies (L.) H. Karst.) was tested in a seed orchard in mid-May or in the beginning of June. The pesticide treatments significantly reduced infestation by Laspeyresia strobiella and Kaltenbachiella strobi only. Variation in the number of cones infested by both insects and cone rusts was high between the spruce clones. Generally, the pesticides did not affect flower viability, seed quality or seed germination, but reduced drastically the germination capacity of pollen in vitro. In practice, sufficient control cannot be achieved with concentrations or methods used in the present study.

The PDF includes an abstract in Finnish.

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

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

The PDF includes an abstract in Finnish.

  • Rikala, ORCID ID:E-mail:
  • Jozefek, ORCID ID:E-mail:
article id 5413, category Article
Eljas Pohtila. (1990). Metsän uudistuminen Kivalon vanhoilla kaistalehakkuualoilla. Silva Fennica vol. 24 no. 1 article id 5413. https://doi.org/10.14214/sf.a15565
English title: Forest regeneration of old strip cutting areas in Kivalo.

The results of regenerating 54 and 36–38-year old strip cuttings were surveyed in the Kivalo Research Forest (N 66°20’, E 26°40’). 15 measurement plots were placed on each strip. The most common forest type was Hylocomnium-Myrtillus type. Regeneration of the strips proved to be slow. Most of the spruces growing on the strips probably originated from the time before the cutting. The average number of stems was 1,155 per ha, of which one third consisted of broadleaved trees. The average volume increment of stem wood after cutting had been about 1 m3/ha/yr, but it was increasing at the time of the inventory. Both the reforestation of the strips and the development of the emergent stands were dependent on elevation and site fertility. Site fertility was indicated by the abundance of Vaccinium myrtillus.

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

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

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

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

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

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  • Huuri, ORCID ID:E-mail:
article id 5392, category Article
Pekka Kilkki, Matti Maltamo, Reijo Mykkänen, Risto Päivinen. (1989). Use of the Weibull function in estimating the basal area dbh-distribution. Silva Fennica vol. 23 no. 4 article id 5392. https://doi.org/10.14214/sf.a15550

The paper continues an earlier study by Kilkki and Päivinen concerning the use of the Weibull function in modelling the diameter distribution. The data consists of spruces (Picea abies (L.) H. Karst.) measured on angle count sample points of the National Forest Inventory of Finland. First, maximum likelihood estimation method was used to derive the Weibull parameters. Then, regression models to predict the values of these parameters with stand characteristics were calculated. Several methods to describe the Weibull function by a tree sample were tested. It is more efficient to sample the trees at equal frequency intervals than at equal diameter intervals. It also pays to take separate samples for pulpwood and saw timber.

The PDF includes an abstract in Finnish.

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

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

The PDF includes an abstract in Finnish.

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

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

The PDF includes an abstract in Finnish.

  • Hänninen, ORCID ID:E-mail:
  • Pelkonen, ORCID ID:E-mail:
article id 5355, category Article
Halvor Rostad. (1988). Frost resistance during shoot elongation in Picea abies seedlings in relation to the growth environment of the previous growing period. Silva Fennica vol. 22 no. 3 article id 5355. https://doi.org/10.14214/sf.a15512

Frost resistance during shoot elongation in seedlings of Norway spruce (Picea abies (L.) H. Karst.) was studied in two experiments. The aim of the first study was to evaluate the effect of varying mineral nutrition. Except for potassium, only minor differences in mineral elements concentrations were established, presumably due to low levels of irradiance and thus a low rate of dry matter production. No significant differences in frost injuries were found between the treatments in the experimental series, but the control seedlings were significantly less injured. It is assumed that poor hardiness development at the end of one growth period resulting from low levels of irradiance may decrease the frost resistance during the next shoot elongation phase. Observations from the second experiment with Norway spruce nursery stocks representing different seedling ages and production systems, support this assumption.

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  • Rostad, ORCID ID:E-mail:
article id 5353, category Article
Øystein Johnsen, Inger Apeland. (1988). Screening early autumn frost hardiness among progenies from Norway spruce seed orchards. Silva Fennica vol. 22 no. 3 article id 5353. https://doi.org/10.14214/sf.a15510

Nursery grown Norway spruce (Picea abies (L.) H. Karst.) seedlings from 12 different seed orchards were tested for early autumn frost hardiness using artificial freezing tests. Seed orchards containing grafted parent clones originating from high altitudes produced seedlings showing higher damage than commercial control seed lots of the commercial controls. A seed orchard containing both German and Norwegian clones produced seedlings showing high damage. The correlation between bud-set and frost damage was high at the provenance level, but lower at the half- and full-sib-levels. Families with good growth capacity in progeny field tests showed large between-family variation in frost damage in the artificial freezing tests. This indicates the possibility to combine high growth rate with acceptable autumn frost hardiness in the selection of parent trees.

The PDF includes an abstract in Finnish.

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

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

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

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

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

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

The PDF includes an abstract in English.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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  • Kärkkäinen, ORCID ID:E-mail:
  • Pietilä, ORCID ID:E-mail:
  • Vihola, ORCID ID:E-mail:
article id 5253, category Article
Carl Johan Westman, Matti Leikola, Tapio Nummi. (1985). Käytännön typpilannoituksen vaikutus varttuneiden kuusikoiden kasvuun ja tuotokseen. Silva Fennica vol. 19 no. 4 article id 5253. https://doi.org/10.14214/sf.a15432
English title: The effect of large-scale nitrogen fertilization on growth and yield of mature Norway spruce stands in south-western Finland.

A method for calculation of the effect of practical fertilization for economic evaluation is presented and discussed. 55 Norway spruce (Picea abies (L.) H. Karst.) dominated stands on Oxalis-Myrtillus type sites were surveyed five to eight years after fertilization with nitrogen (90-170 kg/ha). The relationships between the fertilization effect and various stand characteristics were discussed. Fertilization increased the growth of the stands on an average by 2.2 m3/ha/year. In total the increase of tree growth during the research period was 17.5 m3/ha. This corresponds to a yield of 525–659 FIM/ha.

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  • Westman, ORCID ID:E-mail:
  • Leikola, ORCID ID:E-mail:
  • Nummi, ORCID ID:E-mail:
article id 5249, category Article
Jari Parviainen. (1985). Istuttamalla perustetun nuoren männikön, kuusikon, siperianlehtikuusikon ja rauduskoivikon kasvu. Silva Fennica vol. 19 no. 4 article id 5249. https://doi.org/10.14214/sf.a15428
English title: Growth of young Scots pine, Norway spruce, siberian larch and silver birch plantations.

Early growth of four different tree species (Pinus sylvestris L., Picea abies (L.) H. Karst., Larix sibirica Ledeb and Betula pendula Roth) 16–23 years after planting were compared in a field experiment of 16 square plots established on a stony, grove-like upland (Oxalis-Myrtillus forest type) in Southern Finland. This study gives additional results to the publication Folia Forestalia 386/1979.

At this early stage, the growth of the spruce stand was clearly slower than that of the other species for all parameters to be measured (height, diameter, and volume growth). Height growth was most rapid in the silver birch stand and diameter growth in the larch stand. No clear differences were found in the mean volume of the 100 thickest trees in the stand between the larch and silver birch.

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

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

In each forest stand, a set of hemipherical photographs was taken and standard tree stand measurements were performed. A regression approach was applied in order to elaborate linear models for predicting the canopy coverage. The total basal area of the stand explained 63% of variance in the canopy coverage computed from hemipherical photographs. A coefficient representing the relative proportion of Norway spruce in the stand increased the explanatory power into 75%. When either the stand density (stems/unit area) or dominant age of the stand was included into the model, increment of the explanatory power into 80% was achieved. By incorporating both of the preceding predictors, an explanatory power of 85% was reached.

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  • Kuusipalo, ORCID ID:E-mail:
article id 5238, category Article
Matti Kärkkäinen. (1985). Suomalaisen kuusen puuaineen vertailua Keski-Euroopassa kasvaneiden kuusi- ja jalokuusilajien puuaineeseen. Silva Fennica vol. 19 no. 2 article id 5238. https://doi.org/10.14214/sf.a15417
English title: Norway spruce wood grown in Finland compared with spruce and fir wood grown in Central Europe.

The aim of this literature review was to compare Finnish Norway spruce (Picea abies (L.) H. Karst.) sawn goods to Central European spruce sawn goods which contain fir in some amount. However, it was found that no statistically valid comparisons have been made. Therefore, conclusions have been based mainly on the relationship between various properties and growth rate. According to this analysis, most properties of Finnish spruce are better, although small in practice.

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  • Kärkkäinen, ORCID ID:E-mail:
article id 5233, category Article
Leo Heikurainen. (1985). Verhopuuston vaikutus kuusitaimikon kehitykseen. Silva Fennica vol. 19 no. 1 article id 5233. https://doi.org/10.14214/sf.a15412
English title: The influence of birch nurse crop (Betula pubescens) on the growth of Norway spruce (Picea abies) seedling stands on drained peatlands.

Young Norway spruce (Picea abies (L.) H. Karst.) are susceptible to early summer frost damage. Birch (Betula pubescens Ehrh.) naturally colonize rich or fairly rich drained peatlands after clear cutting, and can provide protection for developing seedlings. The report describes the development of spruce stands after various types of handing of the birch nurse crops.

Different proportions of birch and spruces did not have any influence on the spruce stand production. In cases where the nurse crop stand is removed when the spruce stand age was 20 years and height 4 m the spruce suffered badly but recovered with time, reaching the spruce stand growing under a nurse stand within the next 20 years. The height growth of spruce depends on the density of the nurse stand, especially on fertile sites. The development of diameter growth also depends on the density of the nurse trees. Removal of the nurse stand in spruce stands on the sites concerned should be done when the spruce stand is 20 years old and at the height of 4 m.

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  • Heikurainen, ORCID ID:E-mail:
article id 5231, category Article
Matti Kärkkäinen, Michel Marcus. (1985). Shrinkage properties of Norway spruce wood. Silva Fennica vol. 19 no. 1 article id 5231. https://doi.org/10.14214/sf.a15410

Norway spruce (Picea abies (L.) H. Karst.) boards sawn from outer layers of logs were sampled from a sawmill in Northern Finland and another in Southern Finland. Test pieces 20 mm x 20 mm x 20 mm were selected according to maximum variation in growth ring width. Volumetric and longitudinal shrinkage from a soaked to a dry condition were measured. It was found that wood density correlated positively with the volumetric shrinkage but negatively with the longitudinal shrinkage. Dry density was a better predictor than basic density. With constant density and an increase in growth ring width, there was increased shrinkage, especially in samples from Northern Finland. Besides this, when density was kept constant, the shrinkage was higher in the spruce wood from Southern Finland than from Northern Finland.

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  • Kärkkäinen, ORCID ID:E-mail:
  • Marcus, ORCID ID:E-mail:
article id 7057, category Article
Viljo Kujala. (1921). Havaintoja Kuusamon ja sen eteläpuolisten kuusimetsäalueiden metsä- ja suotyypeistä. Acta Forestalia Fennica vol. 18 no. 5 article id 7057. https://doi.org/10.14214/aff.7057
English title: Observations of forest and peatland site types in Norway spruce areas in Kuusamo.
The forest and peatland site types can be identified based on the ground vegetation. Grazing, forest fires, fellings and other interferences, altitude and soil, however, change the species composition. In Kuusamo area, the land is mountaneous, but the moraine layer is mostly continuous. Thus, there is relatively little rocky sites. In addition, the calcareous soil is more fertile than in the most parts of the country. Norway spruce (Picea abies (L.) H. Karst.) is common on Hylocomium-myrtillus site type, where vegetation differs to some extent from the corresponding forest site types in the southern parts of the country. These changes seem to be caused by the thin stands in the north. In the southern parts of the Kuusamo area, the stands are denser which affects the vegetation. In areas that have been burned, the dominant tree species is mostly Betula sp., and Norway spruce may grow in understorey, and the ground vegetation is herb-rich. The forest become thinner, the higher the altitude. This changes also ground vegetation. Norway spruce is also dominant species in the spruce swamps and transition zones between spruce swamps and the open peatland types.
  • Kujala, ORCID ID:E-mail:
article id 5220, category Article
Peitsa Mikola. (1984). Harsintametsätalous. Silva Fennica vol. 18 no. 3 article id 5220. https://doi.org/10.14214/sf.a15399
English title: Selection system in timber harvesting in Finland.

This article reviews experiments and practical experience of forest management by the selection system in Finland. In an experiment of 25-year duration the annual growth of uneven-aged Norway spruce (Picea abies (L.) H. Karst.) stands was only about 50% of the average annual yield of even-aged stands in normal rotation on the same site.

In Finland the selection system is applicable under exceptional conditions only, viz. In intensively managed park stands and, on the other hand, on very marginal sites, e.g. on peat bogs and mountains near the tree-line. Even normal silviculture, however, may include cuttings which somewhat resemble selection system, e.g. removal of standards or restoration of mismanaged forests.

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  • Mikola, ORCID ID:E-mail:
article id 5216, category Article
Anna-Maija Hallaksela. (1984). Causal agents of butt-rot in Norway spruce in southern Finland. Silva Fennica vol. 18 no. 3 article id 5216. https://doi.org/10.14214/sf.a15395

A total of 146 Norway spruce-dominated clear-cutting areas and 140 of the sample plots included in the 7th National Forest Inventory in Finland were examined during 1974–78. The micro-organisms causing decay in Norway spruce (Picea abies (L.) H. Karst.) sample trees were identified. The most common causal agent of butt-rot was Heterbasidion annosum (Fr.) Bref. Other fungi causing decay in the spruce trees were Armillaria mellea (Vahl.) Quél, Stereum sanguinolentum (Alb. & Schw. ex Fr.), Resinicum bicolor (Alb. & Schw. ex Fr.) Parm. and Climacocystis borealis (Fr.) Kotl. & Pouz. Species of Ascocoryne were very often present in the decay. The decay caused by H. annosum was considerably more extensive than cases of decay where the fungus was not present.

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  • Hallaksela, ORCID ID:E-mail:
article id 5208, category Article
Matti Kärkkäinen. (1984). Effect of tree social status on basic density of Norway spruce. Silva Fennica vol. 18 no. 2 article id 5208. https://doi.org/10.14214/sf.a15387

The effect of growth rate on wood basic density in even-age Norway spruce (Picea abies (L.) H. Karst.) plantations was studied on the basis of samples collected from 53 stands; 30 trees were sampled in each stand. The prediction of basic density with the help of growth rate and some other tree characteristics could be improved if the social status of the tree was taken into account. Within a stand, the smaller trees had a lower density, while taller trees had a higher density than they should have had on the basis of growth rate alone.

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  • Kärkkäinen, ORCID ID:E-mail:
article id 5199, category Article
Pekka Saranpää. (1983). Puuaineen tiheyden ja vuosiluston leveyden vaikutus kuusen iskutaivutuslujuuteen Etelä- ja Pohjois-Suomessa. Silva Fennica vol. 17 no. 4 article id 5199. https://doi.org/10.14214/sf.a15182
English title: The influence of basic density and growth ring width on the impact strength of Norway spruce wood from Southern and Northern Finland.

Basic density and absorbed energy in impact bending were measured for 500 Norway spruce (Picea abies (L.) H. Karst.) samples from Northern and Southern Finland. Statistical analysis showed that the relationship between impact strength and basic density was significant and regression analysis showed that it was linear.

Furthermore, with constant density, the impact strength was higher in Northern than in Southern Finland. This was due to growth ring width: i.e. when density was kept constant the impact strength increased with decreasing growth ring width. In addition, when the growth ring width was kept constant, the basic density of wood was higher in Southern Finland than in Northern Finland.

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  • Saranpää, ORCID ID:E-mail:
article id 5188, category Article
Eljas Pohtila, Tapani Pohjola. (1983). Vuosina 1970-1972 Lappiin perustetun aurattujen alueiden viljelykokeen tulokset. Silva Fennica vol. 17 no. 3 article id 5188. https://doi.org/10.14214/sf.a15171
English title: Results from the reforestation experiment on ploughed sites established in Finnish Lapland during 1970–1972.

The objective of the study was to compare different reforestation methods on ploughed areas in Finnish Lapland. Four species were compared: Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), silver birch (Betula pendula Roth) and Siberian larch (Larix sibirica Ledeb.). The experiments were established in different parts of Lapland on different types of sites in 1970–72.

In Scots pine there was a difference of 15 percentage points in survival of seedlings between the best and worst methods of regeneration. Containerized seedlings and paper pot seedlings had the best survival rates. In Norway spruce the respective difference between sowing and planting was about 20 percentage points. In favour of planting. The survival rate can be increased by about 20 percentage points by selecting the right tree species. The average height varied from 25 cm (the sowed Norway spruce) to 179 cm (the planted silver birch) after 10 growing seasons. The birch was planted at the most fertile sites only. The longer time passed from the afforestation the clearer was the effect of the local growing conditions on the development of the seedlings. The elevation of the site was one factor seemed to influence the success of the seedlings.

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  • Pohtila, ORCID ID:E-mail:
  • Pohjola, ORCID ID:E-mail:
article id 5181, category Article
Matti Kärkkäinen, Olle Dumell. (1983). Kuusipuun taivutuslujuuden riippuvuus tiheydestä ja vuosiluston leveydestä Etelä- ja Pohjois-Suomessa. Silva Fennica vol. 17 no. 2 article id 5181. https://doi.org/10.14214/sf.a15097
English title: Effect of basic density and growth ring width on the bending strength of Norway spruce wood from southern and northern Finland.

A population consisting of 450 Norway spruce (Picea abies (L.) H. Karst.) samples was gathered from northern and southern Finnish wood. The static bending strength was affected greatly by the density of the wood. However, keeping the density constant, the bending strength was higher in northern than in southern Finnish wood. The reason was the effect of the growth ring width.

The basic density was affected by the growth rate. Keeping the growth ring width constant, the basic density was over 5 kg/m3 lower in northern than in southern Finnish wood. This result supports the earlier findings on the effect of latitude.

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  • Kärkkäinen, ORCID ID:E-mail:
  • Dumell, ORCID ID:E-mail:
article id 7042, category Article
Yrjö Ilvessalo. (1920). Kasvu- ja tuottotaulut Suomen eteläpuoliskon mänty-, kuusi- ja koivumetsille. Acta Forestalia Fennica vol. 15 no. 4 article id 7042. https://doi.org/10.14214/aff.7042
English title: Growth and yield tables for the Scots pine, Norway spruce and birch in the southern part of Finland.

The first proper growth and yield tables were prepared in Finland already in 1872, but they have been used little as the needs of forestry and forest sciences increased. One of the problems of the old yield tables was how the site quality classes are determined. The new growth and yield tables use the forest site type classification, which enables the use of same site types for all tree species. This makes it possible to compare the growth of different tree species in same kind of sites. The tables also use stem frequency distribution series. In the first stage, the tables were prepared for Southern and Central Finland.

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  • Ilvessalo, ORCID ID:E-mail:
article id 5136, category Article
Sirkka Soikkeli. (1981). The types of ultrastructural injuries in conifer needles of northern industrial environments. Silva Fennica vol. 15 no. 4 article id 5136. https://doi.org/10.14214/sf.a15363

Ultrastructure of mesophyll of second-year green needles of Picea abies (L.) H. Karst. and Pinus sylvestris (L.) has been studied in several polluted areas in Finland since 1976 (Soikkeli and Tuovinen 1979, Soikkeli 1981a). Four different types of injuries have been found. The types differ with the origin of the material:

1) In needles collected from areas pollute by S-communds the types with reduced grana and/or the with lightening of plastogobuli with simultaneous accumulation of lipid-like material are observed.

2) In needles expose to fluorides (alone or in addition to other pollutants) the type with swollen and/or that with curled thylakoids are found. Both of the latter have also stretched envelopes. In each type of the injury three stages of cell disruption have been described: slight-medium, severe and very severe. On the slight-medium stage the injuries are usually found only in chloroplasts. On severe stage other organelles show injuries, too. In very severe injury all cell organelles are badly disorganized or they disappear completely. The most abundant injuries are usually in needles collected after their second winter. The severity of cell injury depends on the closeness of emission source or on the measured concentration of SO2.

  • Soikkeli, ORCID ID:E-mail:
article id 5128, category Article
Paavo J. Ollinmaa. (1981). Eräistä ojitetuilla soilla kasvaneen puun fysikaalisista ominaisuuksista. Silva Fennica vol. 15 no. 3 article id 5128. https://doi.org/10.14214/sf.a15069
English title: Physical properties of wood growing on drained swamps.

The objective of the investigation was to determine the differences between timber grown on a peatland before and after draining, in respect of compressive strength parallel to the grain, static bending strength and density. In addition, the characteristics of boundary zone between the wood formed before, and after the draining with wider growth rings was studied. 41 Scots pine (Pinus sylvestris L.) and 22 Norway spruce (Picea abies (L.) H. Karst.) trees were studied.

The compressive strength of pine usually decreased from the butt end upwards, but no trend was observed in spruce wood. In coniferous trees, wide-ringed wood formed subsequent to draining was slightly lighter than the close-ringed wood produced prior the draining. The density of pine as well as spruce increases as the width of the growth rings decrease up to a certain limit. The strength of the different kinds of wood seems to decrease from the butt end upwards.

In both species, the compressive strength parallel to the grain and the bending strength are lowest in such wood that contains exclusively wide-ringed wood formed subsequent to draining. Also, compressive and bending strength increase with decreasing width of the growth rings. The longitudinal shrinkage of compression wood in spruce was several times that of normal wood, and the bending strength was lower than that of normal wood particularly in spruce. The compressive strength parallel to the grain in dry condition was, however, higher than in normal wood both in pine and spruce.

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  • Ollinmaa, ORCID ID:E-mail:
article id 5125, category Article
Ilppo Greis, Seppo Kellomäki. (1981). Crown structure and stem growth of Norway spruce undergrowth under varying shading. Silva Fennica vol. 15 no. 3 article id 5125. https://doi.org/10.14214/sf.a15066

The crown structure and stem growth of Norway spruce (Picea abies (L.) H. Karst.) undergrowth was studied in relation to the prevailing light conditions and potential photosynthesis. Shading decreased the stem height growth more than the length increment of laterals, producing a plate-shaped crown in deep shade. Needles responded to shading by adopting a horizontal inclination in deep shade. The needles were wide and thin respectively in shade. In the open the needle cross-section was almost square. Stem radial growth and height growth were both affected by shading exhibiting a linear response to the prevailing light conditions and the potential photosynthesis. Light conditions under dominating trees were closely correlated with the basal area of the dominating trees.

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  • Greis, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
article id 7039, category Article
Olli Heikinheimo. (1920). Pohjois-Suomen kuusimetsien esiintyminen, laajuus ja puuvarastot. Acta Forestalia Fennica vol. 15 no. 1 article id 7039. https://doi.org/10.14214/aff.7039
English title: The distribution and volume of Norway spruce forests in Northern Finland.

Norway spruce (Picea abies (L.) H. Karst.) forests in Northern Finland are situated mainly in the state lands. The survey is based on silvicultural surveys made in the northernmost districts of the state forests. The quality of private lands of the area was deduced based on the adjacent state lands and specific observations. A map was drawn on the distribution of productive Norway spruce forest in the study area.

The continuous Norway spruce forest areas covered 1,112,000 hectares, of which 866,000 hectares were on the state lands. Especially in the northern parts of the area also more fragmented spruce forest could be found (130,000 hectares in the state lands). The estimated total volume of the wood in the forests in the state and private lands was 57.78 million m3 in the continuous spruce forest area. The spruce forests were often situated on hill and fell areas relatively high above the sea level. In the areas north of the 66th parallel, almost half of the forests were above 300 meters above the sea level. Because spruce forests of the state lands were concentrated near watershed areas, the wood harvesting was more expensive, and reduced the value of the state forests. The spruce forests grow usually on fresh mineral soil sites. However, towards north the species was found on drier sites. The stands were mostly pure spruce stands or mixed birch-spruce stands. The older age groups were the most common, but young stands were rare.

  • Heikinheimo, ORCID ID:E-mail:
article id 5081, category Article
Reijo Jokinen. (1980). Metsälannoituksella saatavan kasvunlisäyksen arviointi. Silva Fennica vol. 14 no. 3 article id 5081. https://doi.org/10.14214/sf.a15022
English title: Estimation of growth response achieved through forest fertilization.

Dependence of the growth increase given by fertilization on different stand characteristics is examined in this article. The aim was to determine whether the volume growth increase can be accurately determined beforehand when fertilization is carried out on mineral soil sites at a dosage of 120 kg N/ha. The material consisted mostly on of mature stands ready for cutting, a total of 22 Scots pine (Pinus sylvestris L.) and 20 Norway spruce (Picea abies (L.) H. Karst.) stands. Increase in basal area, height quality class and basal area of the stand were found to best explain the increment and its increase in the regression equations calculated for different types of fertilizer and the control level.

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  • Jokinen, ORCID ID:E-mail:
article id 5070, category Article
Olavi Luukkanen, Stig Johansson. (1980). Flower induction by exogenous plant hormones in Scots pine and Norway spruce grafts. Silva Fennica vol. 14 no. 1 article id 5070. https://doi.org/10.14214/sf.a15011

The aim of the present study was to establish whether hormone treatments would promote flowering in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) grafts under Finnish conditions. Also, an attempt was made to test the efficiency of hormones as well as the variation in response among different clones. Six Scots pine and six Norway spruce clones were selected in each seed orchard based on their flowering intensity, and treated with growth hormones (GA, NAA) of different dosages by spraying. Flowering was observed one year after the treatments.

None of the treated or untreated spruce grafts flowered. However, poor flowering in the natural stands indicated that the environmental conditions during the previous years did not favour flowering. On the other hand, a distinct increase in flowering in Scots pine was observed as a result of spraying with hormone solutions. Treatments with gibberellin had a distinct promoting effect both on male and female flowering in the Scots pine grafts, although the responses varied between the different hormones or clones. The relative effect was generally stronger in male flowering.

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  • Luukkanen, ORCID ID:E-mail:
  • Johansson, ORCID ID:E-mail:
article id 5069, category Article
Jouni Mikola. (1980). The effect of seed size and duration of growth on the height of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) provenances and progenies at the nursery stage. Silva Fennica vol. 14 no. 1 article id 5069. https://doi.org/10.14214/sf.a15010

In this paper the connection between seed weight and amount and duration of growth are studied at the progeny level within stands or climatically uniform areas, and at the provenance level within larger geographic areas. The material consists of materials of several experiments in the nursery of Maisala in Southern Finland in 1971–76. The origins of the plant material used in the different experiments ranged from progenies of individual Scots pine (Pinus sylvestris L.) or Norway spruce (Picea abies (L.) H. Karst.) trees to provenance selections covering almost the whole natural range of these species.

The effect of seed weight on plant height is strongest immediately after germination and subsequently decreases steadily, when the genetic growth properties of the plants themselves become effective. The effect is usually visible at least until the end of the 1st growing season. This relationship varies considerably depending on the material studied. The connections between the duration and the amount of height growth also proved to differ according to the nature of genetic variation. In wide selection of provenances, which show clear genetic differentiation in annual growth rhythm. The variation in the duration of growth accounts for most of the differences in total height growth. At the individual and family level or between provenances of a limited area, there seems to be no clear connection between the duration and the amount of growth. It seems that the duration of the annual growing period is a genetic property, which is not affected by seed weight.

The total height alone in 1-year old test material grown in a greenhouse had hardly any value in the forecasting of growth capacity. The growth differences were caused mainly by the variation in seed size and growth rate differences during the growing period.

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  • Mikola, ORCID ID:E-mail:
article id 5065, category Article
Juhani Niiranen. (1980). Methods used in cutting propagation of forest trees in Finland. Silva Fennica vol. 14 no. 1 article id 5065. https://doi.org/10.14214/sf.a15006

Cutting propagation of forest trees has recently been done in Finland mainly by the Foundation for Forest Tree Breeding. The aim has been to develop methods which could be used in forest nurseries for large scale production of rooted cuttings. Methods are being developed for tree species which seem to offer possibilities for economically profitable vegetative propagation. The most important tree species has been Norway spruce (Picea abies (L.) RH. Karst.), and also larches (Larix sp.), lodgepole pine (Pinus contorta), birches (Betula sp.), alders (Alnus sp.) and hybrid aspen (Populus tremula x P. tremuloides) are propagated. The sensitive rooting phase takes place in plastic greenhouses which have ventilation on the roof top, mist irrigation equipment and separate heating systems for the air and the ground. Methods used for cutting propagation of Norway spruce, lodgepole pine, larch species and broadleaved trees are described.

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  • Niiranen, ORCID ID:E-mail:
article id 5063, category Article
Pirkko Velling. (1980). Variation in the density of wood of different Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst.) origins in provenance tests. Silva Fennica vol. 14 no. 1 article id 5063. https://doi.org/10.14214/sf.a15004

The study concerned with variations in the density of the wood of different provenances in provenance test series of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) RH. Karst.), established in 1931. Increment cores were collected from 10 sample trees from each sample block. The density of the pine wood was noticeably higher than that of spruce. The basic density was in average 450 kg/m3 for Scots pine, and the variation between different origins was 3–9%, while the average basic density of spruce was under 400 kg/m3 and the variation 3–10%. Statistically significant differences were found between the mean basic densities of different provenances in all sub-experiments for spruce, but only in one pine sub-experiment. However, these differences were not due to the altitude or latitude of the place of the origin. Volume growth seems to be the dominant component in the formation of dry matter yield.

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  • Velling, ORCID ID:E-mail:
article id 5062, category Article
I. Etverk. (1980). Geographical variability of the Norway spruce in the Estonian SSR. Silva Fennica vol. 14 no. 1 article id 5062. https://doi.org/10.14214/sf.a15003

The productivity and several morphological features of Estonian Norway spruce (Picea abies L. Karst.) show significant geographical variation. This is no doubt because of differences in the climatic and soil conditions, which in spite of the small area of the country is quite large. In order to check the possible geographical variability of the gene pool, preliminary experiments were carried out in 1969, when seeds from 93 spruce stands originating from 14 forest enterprises were sowed in a nursery. After two years, the seedlings originating from south-eastern Estonia were the tallest. The seedlings from northern origins were smallest. However, it cannot be maintained that spruces from Southern Estonia are of better genotype than genotype from Northern Estonia since the genotypes are evaluated on the basis of ecological conditions under which the experiments are carried out. Another study suggests that an average shift of 7° to the east of the territory for spruces are suitable for cultivation in Estonia.

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  • Etverk, ORCID ID:E-mail:
article id 5061, category Article
Max Hagman. (1980). Experiences with Norway spruce provenances in Finland. Silva Fennica vol. 14 no. 1 article id 5061. https://doi.org/10.14214/sf.a15002

Ecological investigations have shown that Norway spruce (Picea abies (L.) H. Karst.) reached Western Finland about 1,500–1,000 years B.C. and did not reach Åland islands before around the year 0. The species spread into Finland from the east and north-east, having survived the glaciation somewhere in the central parts of the Asian continent. Geographical variation has provided foresters with provenances of better growth and higher economic yield. In Finland, provenances, for instance, from Austria, Eastern Germany, Romania, Southern Poland and Slovakia have been planted in experiments, mostly in various parts of Southern Finland. According to the results of the experiments, it seems that for the more northern parts of Finland and Sweden the best material was to be obtained from north-east Europe.

The Scandinavian countries decided in 1975 to make a common assessment of all the provenance experiments with Norway spruce. The synthesis confirms the earlier view that provenances from the most north-eastern parts of Central Europe are of the greatest value for Finland.

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  • Hagman, ORCID ID:E-mail:
article id 5051, category Article
Aili Tuimala. (1979). Kuusen lahon aiheuttamista puutavaralajisiirtymistä ja kantohintamenetyksistä. Silva Fennica vol. 13 no. 4 article id 5051. https://doi.org/10.14214/sf.a14908
English title: Changes in timber assortments and loss in stumpage prices caused by decay in growing Norway spruce timber.

Material for this study was collected from 26 stands marked for clear cutting in Southern Finland. The volume of decayed Norway spruce (Picea abies (L.) H. Karst.) timber and pulpwood was determined by deducting the volumes of these assortments (as recorded on the measurement certificate) from the volume of the standing trees. To obtain the economic loss, the volume of decayed wood was multiplied by the difference in stumpage prices between spruce timber of pulpwood and pine pulpwood. In the 17 stands of Buyer A the loss in timber volume caused by decay was 5.84% and the loss in stumpage price 2.84 Fmk/m3 (means weighted by volume). The corresponding figures in the 9 stands of Buyer B were 10.87% and 5.50 Fmk/m3, respectively.

At the mean stumpage price level for the felling season 1977-78 the losses in the stands m.f.c. mentioned above were 2.87% per unit price in the stands of Buyer A and 5.75% in the stands of Buyer B.

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  • Tuimala, ORCID ID:E-mail:
article id 5029, category Article
Seppo Kellomäki. (1979). Metsän tarjoamat fyysiset hyödyt yhdyskuntasuunnittelussa. Silva Fennica vol. 13 no. 2 article id 5029. https://doi.org/10.14214/sf.a14885
English title: Benefits of forests in urban environment .

The potentials of forests in abatement of urban noise and air impurities are discussed based on literature and calculations. Excess attenuation of 6–7 dB seems to be possible in noise abatement applying Norway spruce (Picea abies (L.) H. Karst.) plantations. The potential in dust sedimentation is of 10,000–20,000 kg/ha/year and absorbtion to 7 kg/ha/yr. Forests seem also have considerable potential for control of climatic conditions in urban areas. Management of forests in urban environment is discussed. 

This paper was presented in the ‘Man and the Biosphere’ programme Project 2 seminar held on August 24–25 1978 in Hyytiälä research station of University of Helsinki. 

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  • Kellomäki, ORCID ID:E-mail:
article id 5017, category Article
T. Raunemaa, A. Hautojärvi, P. Jartti, J. Laurén, V. Lindfors, J. Räisänen. (1979). Trace element analysis of sound and decayed Norway spruce (Picea abies) by XRF and NAA methods. Silva Fennica vol. 13 no. 1 article id 5017. https://doi.org/10.14214/sf.a14871

Ashed tree samples from sound and decayed Norway spruce (Picea abies (L.) H. Karst.) were studied by means of fast neutron activation analysis, and for comparison, also by X-ray fluorescence analysis. In fast neutron activation analysis, the following elements were detected: (Na), Mg, Al, Si, K, Ca, Mn, Rb, Sr and Ba, and according to the results of the X-ray fluorescence method the elements present in the wood samples were: K, Ca, Mn, Rb, Sr and Ba. A general diminishing was revealed by both methods in most elemental concentrations studied, with exception of K and Rb, when going from a sound tree to a decayed one. The use of the ratio of the amounts of potassium to calcium as an indication of the degree of decay is therefore proposed.

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  • Raunemaa, ORCID ID:E-mail:
  • Hautojärvi, ORCID ID:E-mail:
  • Jartti, ORCID ID:E-mail:
  • Laurén, ORCID ID:E-mail:
  • Lindfors, ORCID ID:E-mail:
  • Räisänen, ORCID ID:E-mail:
article id 5003, category Article
Hannu Saarenmaa. (1978). Kaarnakuoriaisten (Col., Scolytidae) esiintyminen eräässä kanadanmajavan (Castor canadensis Kuhl) aiheuttaman tulvan seurauksena kuolleessa metsikössä. Silva Fennica vol. 12 no. 3 article id 5003. https://doi.org/10.14214/sf.a14857
English title: The occurrence of bark beetles (Col., Scolytidae) in a dead spruce stand flooded by beavers (Castor canadensis Kuhl.) .

 

The aim of the study was to determine which kinds of insects had infected the Norway spruce (Picea abies (L.) H. Karst.) in different stands killed by flooding caused by beavers (Castor canadensis Kuhl), and if there was any danger that they would subsequently cause damage in the surrounding forests. The effect of tree diameter and certain stand characteristics on the fauna of dead trees are discussed. The occurrence of different insect combinations and qualifications for their coexistence were studied.

Pityogenes chalcographus L., Trypodendron lineatum O., Hylurgops palliatus Gyll. and Dryocetes autographus Ratz. occurred most abundantly. 20 phloem or wood boring species were observed in 5 regular succession types. Secondary species occurred in a virgin stand while Ips typographus L. was found at the edge of a felling area. Owing to the flooding, species preferring moist conditions were abundant. In this case damages had not spread to the surrounding forests which, however, might be possible under certain conditions.

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  • Saarenmaa, ORCID ID:E-mail:
article id 4963, category Article
Tapio Lehtiniemi. (1977). Männyn ja kuusen siementen gammasäteilyherkkyyteen vaikuttavista tekijöistä. Silva Fennica vol. 11 no. 1 article id 4963. https://doi.org/10.14214/sf.a14814
English title: Factors affecting gamma-irradiation sensitivity of Scots pine and Norway spruce.

This study, comprising three experiments, aims to determine the effect of the geographical origin of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seeds, and the duration of the time lag between the moisture treatment and subsequent irradiation on the gamma-irradiation sensitivity of seeds.

The studies showed that the greater the irradiation dose seeds were subjected to the slower the rate of germination. In general, small radiation doses (250–1,000 rad) had a stimulating effect and the final germination percentage (36–40 days) increased. However, when the level was further increased, the germination percentage decreased. Air-dry and moistened seeds withstood irradiation better than others. In a study with moistened seeds from different geographical sources, pine and spruce seeds from Northern Finland were less able to withstand irradiation than those originating from the south.

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  • Lehtiniemi, ORCID ID:E-mail:
article id 4941, category Article
Seppo Kellomäki, Pirkko Pohjapelto. (1976). Metsikkösadannan määrä ja vaihtelu eräässä luonnontilaisessa kuusikossa. Silva Fennica vol. 10 no. 2 article id 4941. https://doi.org/10.14214/sf.a14787
English title: The distribution of throughfall in a virgin spruce stand.
Original keywords: kuusi; metsikkösadanta; sademäärä

The aim of the paper was to study the amount and distribution of rainfall in a virgin Norway spruce (Picea abies (L.) H. Karst.) stand. Special attention has been paid to the dependence of throughfall on the characteristics of the precipitation falling on an open area and the stand.

The throughfall was 62% of the precipitation in the open. The best independent variable as regards the throughfall was the amount of precipitation falling in the open. The heaviness of precipitation in the open gave no meaningful correlation. Horizontal layout of the stand was found to have some effect on the throughfall. The throughfall was also influenced by the tree species composition of the stand. Only 52% of the total variance of the amount of water caught by the rain gauges could be predicted with the characteristics of the precipitation in the open and the stand.

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  • Kellomäki, ORCID ID:E-mail:
  • Pohjapelto, ORCID ID:E-mail:
article id 4930, category Article
Tapio Lehtiniemi. (1976). Ionisoivan säteilyn vaikutus varastokuivien ja liotettujen metsäpuiden siementen idäntään ja taimien alkukehitykseen. Silva Fennica vol. 10 no. 1 article id 4930. https://doi.org/10.14214/sf.a14772
English title: Effect of ionizing radiation on the germination of storage-dry and soaked forest tree seeds and on the initial development of seedlings.

The study was carried out in order to find out the changes taking place in germination of seeds in certain tree species as a function of gamma irradiation, the height growth of the seedlings produced and the types of phenotypic mutants possibly found in the generation that had received radiation. The tree species studied were Pinus sylvestris L., Picea abies (L.) H. Karst., Betula verrucosa (Betula pendula Roth), B. Pubescens Ehrh., Alnus glutinosa (L.) Gaertn. and Alnus incana (L.) Moench.

Soaked seeds that had received a rather small dose of radiation germinated usually better than storage-dry seeds, B. pubescens being an exception. The damages observed in germination, height growth and the relative number of mutants were greater the higher the irradiation doses. The LD50 dose (germination, 28 days) was as follows in the case of the different tree species (storage dry/soaked): P. Sylvestris 1,500-2,000/2500-3,000, P. abies 1,000-1,500/4,000-4,500, B. pendula 9,500-10,000/7,000-7,500, B. pubescens >10,000/7,500-8,000 and A. Glutinosa 10,000/8,500-9,000 rad. Mass production of different mutants of deciduous trees for ornamental purposes, for example, appears to be easy using gamma-irradiation. On the other hand, the possibility of increasing tree growth remains open for further study.

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  • Lehtiniemi, ORCID ID:E-mail:
article id 4924, category Article
Teklé Kapustinskaité. (1975). Puuston kasvu ja turpeen tuhkapitoisuus ojitetuilla soilla. Silva Fennica vol. 9 no. 3 article id 4924. https://doi.org/10.14214/sf.a14766
English title: Ash content of peatland soils and stand growth in connection with drainage.

The ash content has been found to correlate with the fertility of peatlands. Relationship between height of 80-year-old stands and ash content of peat in topmost 30 cm layer was examined in Lithuanian conditions. On drained peatlands with ash content of peat from 3% to 8% pine stands increase in height. Ash content of peat being about 7% Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands on drained sites are found to be of equal height. Ash content of peat more than 8–9% has no significant effect on growth of pine or spruce stands. Birch (Betula verrucosa (B. Pendula Roth.) and Betula pubescens Erhrh.), stands are less sensitive to ash content of peat compared with other species. Black alder (Alnus glutinosa L. Gaertn.) stands occurred in sites with ash content of peat more than 8–10%. The height of the stands become equal both in drained and undrained sites in the cases where ash content of peat is about 16–18%. Ash (Fraxinus exelsior L.) stands attain high productivity on drained sites with ash content of peat about 20%.

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  • Kapustinskaité, ORCID ID:E-mail:
article id 4888, category Article
Olavi Luukkanen. (1973). Havaintoja kuusen vapaapölytysjälkeläistöjen ja männyn metsikköalkuperien CO2-aineenvaihdunnasta. Silva Fennica vol. 7 no. 4 article id 4888. https://doi.org/10.14214/sf.a14726
English title: Observations on CO2 exchange in open pollinated progenies of Norway spruce and provenances of Scots pine.

Photosynthesis and dark respiration in five families of autochtonous Norway spruce (Picea abies (L.) H. Karst.) and in seedlings from twenty Finnish stands of Scots pine (Pinus sylvestris L.) were investigated in constant environmental conditions. Values of CO2 exchange were compared with the height growth and weight of seedlings in Norway spruce and with the weight alone in Scots pine. No statistically significant differences were found in CO2 exchange among progenies or stands. Photosynthetic efficiency and photosynthetic capacity showed a positive correlation both in spruce and in pine. Growth and net photosynthetic capacity were linearly and positively correlated in pine. Spruce and a higher light compensation point than pine. The use of an open IRGA system with several simultaneous measurements and the trap-type cuvette construction in genetic work are discussed.

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  • Luukkanen, ORCID ID:E-mail:
article id 4882, category Article
Hannu Mannerkoski. (1973). Ekologisia havaintoja eräältä ojitetulta suolta. Silva Fennica vol. 7 no. 2 article id 4882. https://doi.org/10.14214/sf.a14718
English title: Ecological investigations in a drained peatland area.

The paper deals with the relationships between macronutrients, ground vegetation and tree crop on a drained peatland area in Central Finland. The former herb-rich spruce swamp was drained in 1930s. The Norway spruce (Picea abies (L.) H. Karst.) stand was established by planting under a nurse crop of birch, which was removed later.

There was a negative correlation between the thickness of the peat layer and the volume and mean height of the growing stock. This was found to depend on the negative correlation prevailing between the potassium content of the topmost peat layer and the thickness of the peat cover. The deficiency of potassium is clearly discernible as deficiency symptoms in the needles, the intensity of which showed a strong correlation with the stand characteristics studied. Among the nutrient characteristics of the topmost peat layer, total potassium and the N/K and P/K ratios showed the closest correlation with the stand characteristics. The communities into which the ground vegetation was divided differed from each other with regard to the calcium content of the peat substrate.

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  • Mannerkoski, ORCID ID:E-mail:
article id 4872, category Article
Matti Kärkkäinen. (1972). Kuusen ja männyn sydänpuuosuudesta. Silva Fennica vol. 6 no. 3 article id 4872. https://doi.org/10.14214/sf.a14679
English title: The proportion of heartwood in Norway spruce (Picea abies) and Scots pine (Pinus sylvestris).
Original keywords: kuusi; mänty; sydänpuu; kuitupuu; läpimitta

The study deals with the variation in the proportion of heartwood  in Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) both within and between stems as examined on the basis of literature. Special attention is paid to an application, in which on the basis of the diameter of pulpwood bolts, efforts are made to predict the proportion of heartwood in the total volume of bolts. It is shown that the method, even when based on homogenous material of 564 Norway spruce and Scots pine bolts, easily leads to wrong conclusions concerning the proportion of heartwood.

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  • Kärkkäinen, 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.

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  • Hari, ORCID ID:E-mail:
  • Lehtiniemi, ORCID ID:E-mail:
article id 4865, category Article
Tauno Kallio. (1972). Esimerkki kuusikon lahovikaisuuden Etelä-Suomessa aiheuttamasta taloudellisesta menetyksestä. Silva Fennica vol. 6 no. 2 article id 4865. https://doi.org/10.14214/sf.a14668
English title: An example on the economic loss caused by decay in growing Norway spruce timber in Southern Finland.

A growing stand of Norway spruce (Picea abies (L.) H. Karst.) marked for cutting was investigated in the winter of 1971–72 in Helsinki in Southern Finland in order to determine the economic loss caused by decay. Taking a sample from growing spruce trees with increment borer is not a reliable method of determining the frequency of decay. The decayed stems were twice measured for assortment cutting into lengths; the first time disregarding the decay and the second time doing the actual assortment cutting according to the grade of timber. The direct economic loss caused by decay was 13% of the price for standing timber. The indirect loss may be as great as the direct loss.

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  • Kallio, ORCID ID:E-mail:
article id 4864, category Article
Matti Kärkkäinen. (1972). Havaintoja kuusen oksaisuudesta. Silva Fennica vol. 6 no. 2 article id 4864. https://doi.org/10.14214/sf.a14667
English title: Observations on the branchiness of Norway spruce.

The material comprised 12 Norway spruces (Picea abies (L.) H. Karst.) from Central Finland, with 2,118 branches. The exact location of the branches on the stems, their diameter at the thick end, their length, and the green weight of all the branches was measured on two-metre lengths of the stem.

According to the results, the diameter of a branch can be estimated very accurately from its length. The variation of branch diameter along the stem was also very regular, although there were considerable differences from one tree to another. The greatest work requirement for trimming was in the middle and upper parts of the green crown. Branch variables per tree, such as the number and cross-section area o the branches, could be satisfactorily estimated from the volume or breast-height diameter of the stem.

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  • Kärkkäinen, ORCID ID:E-mail:
article id 4861, category Article
Tauno Kallio, Yrjö Norokorpi. (1972). Kuusikon tyvilahoisuus. Silva Fennica vol. 6 no. 1 article id 4861. https://doi.org/10.14214/sf.a14664
English title: Butt rot in a Norway spruce stand.

The study was carried out in a Norway spruce (Picea abies (L.) H. Karst.) stand in Southern Finland which was to be clear-cut due to decay. The species composition and incidence of decay fungi were investigated from the cut surfaces of the stumps. In addition, the colour and size of the decayed spot was observed.

About 28% of the total number of trees were decayed. Fomes annosus (Heterobasidion annosum) was the most common decay fungus. It was identified from 75% of the decayed trees, and was the sole agent in 43% of these trees. Armillaria mellea was the second commonest decay fungus. It decayed trees mostly in combination with Fomes annosus. The most common colours of the decay produced by F. annosus were reddish or yellowish brown. The decay caused by A. mellea was blackish brown. The causative agent cannot be reliably identified on the basis of the colour of the decayed part.

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  • Kallio, ORCID ID:E-mail:
  • Norokorpi, ORCID ID:E-mail:
article id 4859, category Article
Eljas Pohtila. (1972). Istutuskuoppaan annetun kuparihienofosfaatin vaikutus männyn ja kuusen taimien elossapysymiseen ja pituuskasvuun eräällä kulotetulla ja auratulla uudistusalalla Koillis-Suomessa. Silva Fennica vol. 6 no. 1 article id 4859. https://doi.org/10.14214/sf.a14662
English title: Effect of fine-grounded copper rock phosphate placed in the planting hole on the survival and height growth of Scots pine and Norway spruce in a burnt and furrowed reforestation are in northeast Finland.

The paper describes the results of a fertilization experiment, in which transplants of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) were fertilized with various doses of fine-ground copper rock phosphate (33% P2O5, 4% Cu) placed direct in the planting hole. The experiment was made in northeast Finland on a clear-cut, burnt-over and furrowed moraine heath. The fertilization increased especially the survival and condition of the Scots pines and increased to some extent also the height growth of the plants. The spruce survived better than the pines.

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  • Pohtila, ORCID ID:E-mail:
article id 4854, category Article
G. M. Kozubov. (1971). Elektronimikroskooppisia tutkimuksia männyn ja kuusen kukka-aiheiden kehityksestä. Silva Fennica vol. 5 no. 4 article id 4854. https://doi.org/10.14214/sf.a14656
English title: Electron microscopic studies in the development of strobile primordia of Scots pine and Norway spruce.

This article is an abstract from a lecture given in Helsinki on 2.12.1970. Physiological differences in different parts of developing primordia of micro- and macrostrobiles are manifested in the ultrastructure of the cell tissues. In electron microscopy, the study off metabolic activities can be combined with the anatomical examination of the flower primordia.

The generative cells of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) develop under the strong metabolic activity of surrounding layers of cells. Simultaneously the activity and development of the organelles in generative cells becomes hindered, and these inhibitions will exist until the fertilization. It can be concluded that the higher the gradient of sexualization of the cells in different parts of flower primordia, the weaker the metabolic activity in these cells.

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  • Kozubov, ORCID ID:E-mail:
article id 4853, category Article
Olavi Luukkanen, Pentti K. Räsänen, Paavo Yli-Vakkuri. (1971). Neulasten väri myöhemmän kasvun ja lannoitusvaikutuksen ilmaisijana. Silva Fennica vol. 5 no. 4 article id 4853. https://doi.org/10.14214/sf.a14655
English title: The use of needle colour in predicting growth and response to fertilization.
Original keywords: mänty; kuusi; taimet; lannoitus; neulaset; kasvu

About 4,000 seedlings of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) were planted in 1965 both on a clear-cut and sheltered area in Central Finland. In the autumn of 1966 needle colour was determined by using Muncell Color Charts which allowed a quantitative measurement of three colour dimensions (hue, value, and chroma). Terminal shoot growth was recorded for two years after colour measurements. In both species, fertilization (NPK in the spring of the year of colour measurement) as well as other site factors caused differences in all three dimensions of needle colour. A regression of shoot growth on needle colour was found in both species. In most cases colour value (darkness) and, in spruce, also chroma, predicted the subsequent growth almost as well as did these two-colour variables together.

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  • Luukkanen, ORCID ID:E-mail:
  • Räsänen, ORCID ID:E-mail:
  • Yli-Vakkuri, ORCID ID:E-mail:
article id 4848, category Article
Matti Kärkkäinen. (1971). Lahon leviäminen puunkorjuun aiheuttamista kuusen runko- ja juurivaurioista. Silva Fennica vol. 5 no. 3 article id 4848. https://doi.org/10.14214/sf.a14650
English title: Decay following logging injury in stems and roots of Norway spruce.

The material of 78 damaged Norway spruce (Picea abies (L.) H. Karst.) trees was gathered in Southern Finland in order to clarify the advance of decay. The harvesting which had caused the scars had been carried out 12 years earlier and at the moment of the investigation the growing stand was 110 years old. It was noticed that the variables used could explain only a few per cent of the variation of the advance of decay. It was concluded that the only important thing in practice is whether the injuries are in roots or in stems.

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  • Kärkkäinen, ORCID ID:E-mail:
article id 4841, category Article
Hannu Mannerkoski. (1971). Lannoituksen vaikutus kylvösten ensi kehitykseen turvealustalla. Silva Fennica vol. 5 no. 2 article id 4841. https://doi.org/10.14214/sf.a14643
English title: Effect of fertilization on the initial development of Scots pine and Norway spruce plantations established by sowing on peat.

Experiments were carried out to find out the effect of fertilizer application on germination, seedling emmergnece and initial development in conifer plantations established on peat by sowing, with a special reference to Scots pine (Pinus sylvestris L.). The experiments were carried out in 1968–70 in laboratory, in greenhouse and in the field.

In the greenhouse experiments with Y fertilizer for peat soils (14% N, 18% P2O5, 10% K2O) it was shown that germination and seedling emergence decreased markedly with increased fertilizer application. Mortality among seedlings that had emerged was the higher the larger quantities of fertilizer had been applied. The effect of fertilization was the greater, the drier the substrate. Fine ground rock phosphate (33% P2O5) promoted seedling emergence on a dry substrate but not on a wet one.

The field experiments carried out in Central Finland included dry and wet sites. Y fertilizer, Oulu Saltpeter (25% N), fine-ground rock phosphate and potassium salt (50% K2O) were used. According to the results, easily soluble fertilizers decreased seedling emergence. On wet sites the effect of Y fertilizer was weaker than on drier sites. Fine-ground rock phosphate slightly increased the number of seedlings emerging. Height growth was increased during the first three growing seasons only by those fertilizers containing phosphorus.

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  • Mannerkoski, ORCID ID:E-mail:
article id 4840, category Article
Paavo Yli-Vakkuri. (1971). Havaintoja latvakasvainten pakkasvaurioista kuusen taimistoissa Itä-Savossa. Silva Fennica vol. 5 no. 2 article id 4840. https://doi.org/10.14214/sf.a14642
English title: Winter frost damages to the leaders of Norway spruce saplings in Eastern South-Finland.
Original keywords: Itä-Savo; kuusi; pakkasvauriot; pääverso

In the eastern parts of South-Finland the growing season of 1967 was highly favourable, which resulted in good height growth during the following year. During the summer 1968, temperature conditions were unfavourable, while the middle of summer was cold and the later part of the growing season unusually hot. The following winter had exceptionally cold spells from January to March, which caused Norway spruce (Picea abies (L.) H. Karst.) abundant winter frost damages such as dead shoots and buds, and destroyed needles.

These damages occurred particularly in stands with height of 0.5–3 m, and the occurrence of damages seemed to concentrate to the parts of saplings that had been immediately above the snow cover. Detailed observations on spruce plantations growing under a dense nurse stand of alder (Alnus sp.) indicated that explicitly the top shoots suffered from damages and not so much the laterals. When the needles of the leader suffered from minor damages, the shoot continued to grow normally. Still, sometimes a branch took over and became a new leader. If only the leader bud was killed, further stem development became dependent on one of the topmost lateral buds. When the upper part of the leaded died, one of the lateral shoots at its base usually became the new leader.

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  • Yli-Vakkuri, ORCID ID:E-mail:
article id 4835, category Article
Kari Löyttyniemi. (1971). Havupunkin, Oligonychus ununguis (Jacobi), aiheuttaman neulasvioituksen vaikutuksesta kuusen taimien kasvuun. Silva Fennica vol. 5 no. 1 article id 4835. https://doi.org/10.14214/sf.a14624
English title: Influence of damage caused to needles of Norway spruce by spruce spider mite, Oligonychus ununguis, on seedling growth.

The study was carried out in order to establish the possible influence of damage caused to the needles of Picea abies (L.) H. Karst. by the spruce spider mite, Oligonychus ununguis (Jacobi), and the growth of the damaged seedlings. The study was carried out in 1968–1970 by comparing growth of seedlings infected with spruce spider mite with that of seedlings where mites had been killed with acaricide (Eradex®). In the seedlings that had not been treated with acaricide, the number of wintering eggs were 60, 20 and 5 per shoot in the various years of the study. When the experiment was laid out, before planting and acaricide treatment, the seedlings were four years old, all seadlings were heavily infected, the number of wintering eggs being 100 per shoot. The growth of infected seedlings was 3, 20 and 15% smaller than that obtained for the seedlings which had been treated with acaricide.

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  • Löyttyniemi, ORCID ID:E-mail:
article id 4831, category Article
Lauri Mikkola. (1970). Kuusilajien risteytyvyydestä. Silva Fennica vol. 4 no. 4 article id 4831. https://doi.org/10.14214/sf.a14620
English title: On the crossability of Picea species.

Seed development was microscopically studied after controlled pollinations. In all the interspecific crosses incompatibility occured. In the following crosses the growth of all the pollen tubes stopped before they had penetrated through the nuclear cap: Picea abies (L.) Karst. x mariana, abies x jezoensis (and the reciprocal), abies x omorika (and the reciprocal), mariana x asperata, mariana x jezoensis and Picea abies x Pinus sylvestris L.

Some of the eggs were fertilized in the crosses Picea abies x glauca (and the reciprocal) abies x asperata, abies x koyamai, abies x obovata, mariana x omorika and jezoensis x omorika. Embryo degeneration was observed in all these crosses. All the embryos died in the crosses abies x glauca (and the reciprocal) as well as jezoensis x omorika. Adequate amounts of full seed for germination test was obtained from the crosses abies x asperata, abies x koyamai and abies x obovata. In all these crosses there were seeds which were able to germinate and the hybrids are now one growth season old.

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  • Mikkola, ORCID ID:E-mail:
article id 4831, category Article
Lauri Mikkola. (1970). Kuusilajien risteytyvyydestä. Silva Fennica vol. 4 no. 4 article id 4831. https://doi.org/10.14214/sf.a14620
English title: On the crossability of Picea species.

Seed development was microscopically studied after controlled pollinations. In all the interspecific crosses incompatibility occured. In the following crosses the growth of all the pollen tubes stopped before they had penetrated through the nuclear cap: Picea abies (L.) Karst. x mariana, abies x jezoensis (and the reciprocal), abies x omorika (and the reciprocal), mariana x asperata, mariana x jezoensis and Picea abies x Pinus sylvestris L.

Some of the eggs were fertilized in the crosses Picea abies x glauca (and the reciprocal) abies x asperata, abies x koyamai, abies x obovata, mariana x omorika and jezoensis x omorika. Embryo degeneration was observed in all these crosses. All the embryos died in the crosses abies x glauca (and the reciprocal) as well as jezoensis x omorika. Adequate amounts of full seed for germination test was obtained from the crosses abies x asperata, abies x koyamai and abies x obovata. In all these crosses there were seeds which were able to germinate and the hybrids are now one growth season old.

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  • Mikkola, ORCID ID:E-mail:
article id 4817, category Article
Leo Heikurainen, Jukka Ouni. (1970). Turvemaiden taimistojen pituuskasvusta. Silva Fennica vol. 4 no. 2 article id 4817. https://doi.org/10.14214/sf.a14606
English title: Height growth of seedling stands growing on peatland.

This paper presents the results of a contest performed on behalf of the Finnish bank Kansallis-Osake-Pankki and the Central Forestry Board Tapio on growing trees on peatlands. Over 5,000 sample plots were established on drained peatlands in various parts of Finland. The aim was to achieve a best possible growth of seedling stands on peatland. The factors influencing the growth of 85 best Scots pine (Pinus sylvestris L.) and 60 best Norway spruce (Picea abies (L.) H.Karst.) sample plots were studied.

The height growth of the seedling stands decreased towards the north. Fertilization seemed not to decrease the regional differences; rather on the contrary. On the other hand, fertilization increased height growth, but evidently so that the increase obtained was greater in the southern than in the northern parts of the country. Light fertilization (50 kg/ha of K2O and 60 kg/ha of O2P5) caused a clear increase in height growth while heavy fertilization (100 g/ha of K2O and 120 kg/ha of O2P5), had same effect but to much greater extent than the former. Spruce seedling stands in particular benefitted of the heavy fertilization.

Fertilization did not eliminate the original differences in the quality of the sites in question, but these could still be seen in the height growth after fertilization. The effect of drain spacing on the height growth was not very clear. In dense seedling stands (800 seedlings/ha) the height growth of the dominant seedlings was greater than that obtained in stands of lower density. Hold-overs caused a decrease in the growth of the seedling stands.

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  • Heikurainen, ORCID ID:E-mail:
  • Ouni, ORCID ID:E-mail:
article id 4810, category Article
Pentti Solin. (1970). Kuusen käpyjen säilyttäminen jäähdyttämössä ja sen vaikutus niistä saatavan siemenen itävyyteen. Silva Fennica vol. 4 no. 1 article id 4810. https://doi.org/10.14214/sf.a14598
English title: Cold storage of Norway spruce cones and its effect on seed viability.

The aim of the study was to establish how the cold storage of cones of Norway spruce (Picea abies (L.) H. Karst.) affects the viability of the seeds and the percentage ratio in 7 days. A parallel study was made of the longevity of seed in barn-stored cones subject to weather fluctuations and the longevity of seed extracted immediately and stored in the conventional way in an air-tight container. The cones were collected near Kuopio in Central Finland and near Tampere.

The viability and germination rate of the control sample was constant throughout the storage period. This storage method proved the best. The viability of seeds kept in cones declined in cold storage after 3 ½ months. The cones collected in Tampere were damaged by Laspeyresia strobilella, which affected the viability of the seeds.

The viability of seeds stored in cones in a barn had not weakened by the end of May, however, they deteriorated during the summer, as did the seeds stored in cones in the cold storage. Viability of the seeds was still 94% in October. The germination rate was constant in each lot up to the end of May, after which it decreased to 81.7–86.1% in October.

The results show that healthy spruce cones can be stored in paper sacks in a single layer in cold storage and in an ordinary barn for several months without it affecting the viability of the seeds.

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  • Solin, ORCID ID:E-mail:
article id 4803, category Article
Kari Löyttyniemi. (1969). Männyn ja kuusen siemenien esikäsittelyn vaikutuksesta itämiseen ja taimien alkukehitykseen kasvihuoneoloissa. Silva Fennica vol. 3 no. 3 article id 4803. https://doi.org/10.14214/sf.a14591
English title: The effect of treatment of Scots pine and Norway spruce seeds on their germination and the early development of the seedlings.

The aim of this study was to establish the need of treatment of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seeds to be sown in greenhouse. 3 x 100 seeds of each treatment (soaking in water, treatment with Pb3O4, treatment with tiram-containing coating substance) were sown in a glasshouse on a fertilized garden peat, and covered with peat layer of 6 mm thickness. The development of seedlings was followed for 100 days before the final measurement.

Soaking the seeds with water made germination somewhat faster. In spruce the germination percentage increased, but the opposite was observed in pine. No difference could be observed between the results from soaking with acid water from peat soil and lake water. Drying the soaked seeds for a week before sowing had no harmful influence on the germination or the early development of the seedlings. Treatment with Pb3O4 did not affect the germination speed or the seedling percentage of pine or spruce, but increased the germination percentage of spruce. Coating decreased germination and seedling percentages in pine. However, the differences between the treatments were so small that their practical significance is negligible.

Germination of both the species initiated on an average in 8 days, and 16 days after sowing 80% of the seeds had germinated. Seedling mortality was about 10% of the total number of seedlings, the most common reason being damping-off.

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  • Löyttyniemi, ORCID ID:E-mail:
article id 4802, category Article
Kari Löyttyniemi. (1969). Äkämäpunkkilaji (Nalepella haarlovi var. piceae-abietis Löyttyniemi, Acarina, Eriophyidae) kuusen taimien tuholaisena taimitarhoissa. Silva Fennica vol. 3 no. 3 article id 4802. https://doi.org/10.14214/sf.a14590
English title: An Eriophyidae species damaging Norway spruce seedlings in nurseries in Finland.

In Finland the mite Nalepella is found in Norway spruce (Picea abies (L.) H. Karst.) in forests practically in every tree, and even in the nurseries. The paper reports on the occurrence of Nalepella Haarlovi var. picea-abietis Löyttyniemi in Finland in tree nurseries in Finland. The study is based on a large material, collected in connection with an investigation into spruce spider mites.

Nalepella lives vagrantly on the needles. Due to the sucking of the mites, the needles turn yellow, become dry an die. Single patches from sucking cannot be seen by the naked eye. They occur on all sides of the needles. The worst damage to spruce seedlings in nurseries is caused to the needles located in the top of the seedling. Sometimes the terminal bud dryes and the whole terminal shoot can die. However, the whole seedlings seldom die in consequence of the Nalepella mite alone. Subsequent damage to the injured needles is often caused by fungus Cladosporium herbarum.

The study shows that the mite causes economically significant damages only in the nurseries. In forests no such damages were observed in seedlings or in older trees. In 1965–68, significant damages occurred in 16 nurseries in Finland. About 600,000 four-year-old seedlings were destroyed in 1967. The damages were economically important only in the 4-year-old seedlings.

According to the study, seedlings damaged by Nalepella can be used for planting as they recover rather well after planting in the forest. Moreover, the damages end after planting, and density of the mite population decreases during the first summer.

The mite overwinters as egg on needles. The eggs hatch in Southern Finland in the end of April and in the beginning of May.

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  • Löyttyniemi, 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.

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  • Leikola, ORCID ID:E-mail:
  • Pylkkö, ORCID ID:E-mail:
article id 7529, category Article
Lauri Ilvessalo. (1913). Versuche mit ausländischen Holzarten im Staatsforst Vesijako. Acta Forestalia Fennica vol. 2 no. 2 article id 7529. https://doi.org/10.14214/aff.7529
English title: Experiments with foreign tree species in state forest Vesijako, Finland.

The study area is state owned forest of Vesijako in southern middle Finland that has earlier been intensively managed with slash-and-burn agriculture and then partly reforested with foreign coniferous tree species after controlled burnings. The total area planted with foreign species consists of 66 sample areas, altogether 28 hectares. The data has been collected in summer 1909. 

The most of studied sample areas have been unsuccessful, but there are still many areas that are too young to be assessed. The originally with foreign species reforested areas are now pine stands. The tree species in experiments have been e.g. larch (Larix sibirica and L. europaea), Siberian stone pine (Pinus cembra sibirica), Siberian fir (Abies sibirica o. pichta), balsam fir (Abies balsamea), white fir (Abies pectinate also Abies alba), white spruce (Picea alba also Picea glauca), Weymouth pinen (Pinus strobus) and European / Swiss mountain pine (Pinus montana  also P. mugo, P. mugho).

The most important result of the experiments with controlled burning is that stand of grey alder (Alnus incana) with only low economic value can be effectively altered into coniferous forests (Pinus silvestris).
  • Ilvessalo, ORCID ID:E-mail:
article id 7529, category Article
Lauri Ilvessalo. (1913). Versuche mit ausländischen Holzarten im Staatsforst Vesijako. Acta Forestalia Fennica vol. 2 no. 2 article id 7529. https://doi.org/10.14214/aff.7529
English title: Experiments with foreign tree species in state forest Vesijako, Finland.

The study area is state owned forest of Vesijako in southern middle Finland that has earlier been intensively managed with slash-and-burn agriculture and then partly reforested with foreign coniferous tree species after controlled burnings. The total area planted with foreign species consists of 66 sample areas, altogether 28 hectares. The data has been collected in summer 1909. 

The most of studied sample areas have been unsuccessful, but there are still many areas that are too young to be assessed. The originally with foreign species reforested areas are now pine stands. The tree species in experiments have been e.g. larch (Larix sibirica and L. europaea), Siberian stone pine (Pinus cembra sibirica), Siberian fir (Abies sibirica o. pichta), balsam fir (Abies balsamea), white fir (Abies pectinate also Abies alba), white spruce (Picea alba also Picea glauca), Weymouth pinen (Pinus strobus) and European / Swiss mountain pine (Pinus montana  also P. mugo, P. mugho).

The most important result of the experiments with controlled burning is that stand of grey alder (Alnus incana) with only low economic value can be effectively altered into coniferous forests (Pinus silvestris).
  • Ilvessalo, ORCID ID:E-mail:
article id 7529, category Article
Lauri Ilvessalo. (1913). Versuche mit ausländischen Holzarten im Staatsforst Vesijako. Acta Forestalia Fennica vol. 2 no. 2 article id 7529. https://doi.org/10.14214/aff.7529
English title: Experiments with foreign tree species in state forest Vesijako, Finland.

The study area is state owned forest of Vesijako in southern middle Finland that has earlier been intensively managed with slash-and-burn agriculture and then partly reforested with foreign coniferous tree species after controlled burnings. The total area planted with foreign species consists of 66 sample areas, altogether 28 hectares. The data has been collected in summer 1909. 

The most of studied sample areas have been unsuccessful, but there are still many areas that are too young to be assessed. The originally with foreign species reforested areas are now pine stands. The tree species in experiments have been e.g. larch (Larix sibirica and L. europaea), Siberian stone pine (Pinus cembra sibirica), Siberian fir (Abies sibirica o. pichta), balsam fir (Abies balsamea), white fir (Abies pectinate also Abies alba), white spruce (Picea alba also Picea glauca), Weymouth pinen (Pinus strobus) and European / Swiss mountain pine (Pinus montana  also P. mugo, P. mugho).

The most important result of the experiments with controlled burning is that stand of grey alder (Alnus incana) with only low economic value can be effectively altered into coniferous forests (Pinus silvestris).
  • Ilvessalo, ORCID ID:E-mail:
article id 7529, category Article
Lauri Ilvessalo. (1913). Versuche mit ausländischen Holzarten im Staatsforst Vesijako. Acta Forestalia Fennica vol. 2 no. 2 article id 7529. https://doi.org/10.14214/aff.7529
English title: Experiments with foreign tree species in state forest Vesijako, Finland.

The study area is state owned forest of Vesijako in southern middle Finland that has earlier been intensively managed with slash-and-burn agriculture and then partly reforested with foreign coniferous tree species after controlled burnings. The total area planted with foreign species consists of 66 sample areas, altogether 28 hectares. The data has been collected in summer 1909. 

The most of studied sample areas have been unsuccessful, but there are still many areas that are too young to be assessed. The originally with foreign species reforested areas are now pine stands. The tree species in experiments have been e.g. larch (Larix sibirica and L. europaea), Siberian stone pine (Pinus cembra sibirica), Siberian fir (Abies sibirica o. pichta), balsam fir (Abies balsamea), white fir (Abies pectinate also Abies alba), white spruce (Picea alba also Picea glauca), Weymouth pinen (Pinus strobus) and European / Swiss mountain pine (Pinus montana  also P. mugo, P. mugho).

The most important result of the experiments with controlled burning is that stand of grey alder (Alnus incana) with only low economic value can be effectively altered into coniferous forests (Pinus silvestris).
  • Ilvessalo, ORCID ID:E-mail:
article id 7529, category Article
Lauri Ilvessalo. (1913). Versuche mit ausländischen Holzarten im Staatsforst Vesijako. Acta Forestalia Fennica vol. 2 no. 2 article id 7529. https://doi.org/10.14214/aff.7529
English title: Experiments with foreign tree species in state forest Vesijako, Finland.

The study area is state owned forest of Vesijako in southern middle Finland that has earlier been intensively managed with slash-and-burn agriculture and then partly reforested with foreign coniferous tree species after controlled burnings. The total area planted with foreign species consists of 66 sample areas, altogether 28 hectares. The data has been collected in summer 1909. 

The most of studied sample areas have been unsuccessful, but there are still many areas that are too young to be assessed. The originally with foreign species reforested areas are now pine stands. The tree species in experiments have been e.g. larch (Larix sibirica and L. europaea), Siberian stone pine (Pinus cembra sibirica), Siberian fir (Abies sibirica o. pichta), balsam fir (Abies balsamea), white fir (Abies pectinate also Abies alba), white spruce (Picea alba also Picea glauca), Weymouth pinen (Pinus strobus) and European / Swiss mountain pine (Pinus montana  also P. mugo, P. mugho).

The most important result of the experiments with controlled burning is that stand of grey alder (Alnus incana) with only low economic value can be effectively altered into coniferous forests (Pinus silvestris).
  • Ilvessalo, ORCID ID:E-mail:
article id 7529, category Article
Lauri Ilvessalo. (1913). Versuche mit ausländischen Holzarten im Staatsforst Vesijako. Acta Forestalia Fennica vol. 2 no. 2 article id 7529. https://doi.org/10.14214/aff.7529
English title: Experiments with foreign tree species in state forest Vesijako, Finland.

The study area is state owned forest of Vesijako in southern middle Finland that has earlier been intensively managed with slash-and-burn agriculture and then partly reforested with foreign coniferous tree species after controlled burnings. The total area planted with foreign species consists of 66 sample areas, altogether 28 hectares. The data has been collected in summer 1909. 

The most of studied sample areas have been unsuccessful, but there are still many areas that are too young to be assessed. The originally with foreign species reforested areas are now pine stands. The tree species in experiments have been e.g. larch (Larix sibirica and L. europaea), Siberian stone pine (Pinus cembra sibirica), Siberian fir (Abies sibirica o. pichta), balsam fir (Abies balsamea), white fir (Abies pectinate also Abies alba), white spruce (Picea alba also Picea glauca), Weymouth pinen (Pinus strobus) and European / Swiss mountain pine (Pinus montana  also P. mugo, P. mugho).

The most important result of the experiments with controlled burning is that stand of grey alder (Alnus incana) with only low economic value can be effectively altered into coniferous forests (Pinus silvestris).
  • Ilvessalo, ORCID ID:E-mail:
article id 7529, category Article
Lauri Ilvessalo. (1913). Versuche mit ausländischen Holzarten im Staatsforst Vesijako. Acta Forestalia Fennica vol. 2 no. 2 article id 7529. https://doi.org/10.14214/aff.7529
English title: Experiments with foreign tree species in state forest Vesijako, Finland.

The study area is state owned forest of Vesijako in southern middle Finland that has earlier been intensively managed with slash-and-burn agriculture and then partly reforested with foreign coniferous tree species after controlled burnings. The total area planted with foreign species consists of 66 sample areas, altogether 28 hectares. The data has been collected in summer 1909. 

The most of studied sample areas have been unsuccessful, but there are still many areas that are too young to be assessed. The originally with foreign species reforested areas are now pine stands. The tree species in experiments have been e.g. larch (Larix sibirica and L. europaea), Siberian stone pine (Pinus cembra sibirica), Siberian fir (Abies sibirica o. pichta), balsam fir (Abies balsamea), white fir (Abies pectinate also Abies alba), white spruce (Picea alba also Picea glauca), Weymouth pinen (Pinus strobus) and European / Swiss mountain pine (Pinus montana  also P. mugo, P. mugho).

The most important result of the experiments with controlled burning is that stand of grey alder (Alnus incana) with only low economic value can be effectively altered into coniferous forests (Pinus silvestris).
  • Ilvessalo, ORCID ID:E-mail:
article id 7529, category Article
Lauri Ilvessalo. (1913). Versuche mit ausländischen Holzarten im Staatsforst Vesijako. Acta Forestalia Fennica vol. 2 no. 2 article id 7529. https://doi.org/10.14214/aff.7529
English title: Experiments with foreign tree species in state forest Vesijako, Finland.

The study area is state owned forest of Vesijako in southern middle Finland that has earlier been intensively managed with slash-and-burn agriculture and then partly reforested with foreign coniferous tree species after controlled burnings. The total area planted with foreign species consists of 66 sample areas, altogether 28 hectares. The data has been collected in summer 1909. 

The most of studied sample areas have been unsuccessful, but there are still many areas that are too young to be assessed. The originally with foreign species reforested areas are now pine stands. The tree species in experiments have been e.g. larch (Larix sibirica and L. europaea), Siberian stone pine (Pinus cembra sibirica), Siberian fir (Abies sibirica o. pichta), balsam fir (Abies balsamea), white fir (Abies pectinate also Abies alba), white spruce (Picea alba also Picea glauca), Weymouth pinen (Pinus strobus) and European / Swiss mountain pine (Pinus montana  also P. mugo, P. mugho).

The most important result of the experiments with controlled burning is that stand of grey alder (Alnus incana) with only low economic value can be effectively altered into coniferous forests (Pinus silvestris).
  • Ilvessalo, ORCID ID:E-mail:
article id 4756, category Article
Bo Eklund. (1967). Om tillväxtens årliga variation hos tall och gran jämte betydelsen av hänsynstaganden härtil. Silva Fennica vol. 1 no. 4 article id 4756. https://doi.org/10.14214/sf.a14540
English title: Annual variation of increment in Scots pine and Norway spruce in Sweden.

This lecture discusses the problem of the annual variation in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.), and its significance. A newly constructed instrument for field measurements of diameter growth is described, also the latest of the Royal College of Forestry’s series of machines for annual ring measurement. The method of constructing an annual ring index is also mentioned.

Examination of material from undisturbed stands in Northern Sweden has shown that the annual ring index series for pine are characterised by a relatively marked autocorrelation, which increases with latitude, implying that the annual ring index for a given calendar year is positively correlated with that for the year immediately preceding it. However, this seems not to be so in spruce, in which the annual ring index series is marked by the effect of the changes in cone production from the year to year. The annual ring index for spruce may be expressed in the form of climatic functions, according to which the index can be approximately calculated or known values of the meteorological variables contained in the function, in association with numerical expressions for the cone production. By means of a number of examples illustrating annual ring series from thinned stands. It is shown finally how the response to thinning can be presented in a more essential form from the variation in the annual rings, and how climatically corrected increment can be determined.

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  • Eklund, ORCID ID:E-mail:
article id 4745, category Article
Ilmari Schalin. (1967). Microfungi in the humus layer of pine, spruce and birch stands in southern Finland. Silva Fennica vol. 1 no. 2 article id 4745. https://doi.org/10.14214/sf.a14455

This study elucidates the composition of the microfungal populations of the humus layer of tree forest types – Vaccinium type with Scots pine (Pinus sylvestris L.), Myrtillus type with Norway spruce (Picea abies (L.) H. Karst.) and Oxalis-Myrtillus type with birch (Betula sp.). The results indicate that the microfungi encountered in these sites bear close resemblances. The number of species increased but little towards the more fertile sites from VT to OMT. The main difference was limited to the quantitative relationships between the species.

The microfungal density in the humus layer was greatest in VT, and only slightly less in MT and OMT, in this order. In all the sampling areas, occurrence of the microfungi reached a maximum in the middle of summer, at a time when the maximum temperatures were registered in the humus. The quantitative abundance during the early autumn bears a relation to the yield of litter.

The microfungi most commonly encountered in all sampling areas were those of rapid growth, Mucor, Morierella and Penicillium species, along with Trichoderma, a little slower in growth, and actively decomposing cellulose. Mucor fungi, favouring moisture, were most abundant in the early summer and in the autumn. The Mortierella and Penicillium species, which survive dryness, were most abundant in the middle of the summer. The former is twice as common in MT and OMT than in VT, and the latter twice as common in VT as in OMT.

Scopulariopsis and Verticillium species were found regularly in MT and OMT. One Acremonium species was found almost exclusively in VT, and some Aspergillus and Mycogene in OMT alone. Sterilia mycelia was relatively abundant in MT and OMT in particular. Different kinds of yeast fungi were encountered generally in MT and OMT.

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  • Schalin, ORCID ID:E-mail:
article id 4738, category Article
Sakari Lilja. (1967). Tuomen merkityksestä kuusen tuomiruostesienen, Pucciniastrum padi (Kunze & Schm.) Diet., esiintymiselle kuusessa. Silva Fennica vol. 1 no. 1 article id 4738. https://doi.org/10.14214/sf.a14448
English title: Significance of the bird-cherry (Prunus padus L.) for the occurrence of the rust, Puccinastrum padi (Kunze & Schm.) in spruce.

The present study deals with the occurrence of the rust, Pucciniastrum padi (Kunze & Schm.) Diet., in the shoots and cones of Norway spruce (Picea abies (L.) H. Karst.) in the forest area of the training and experimental farm of Helsinki University at Viikki (60’10’ N; 25’ E). The most important task was to clarify the correlation between the occurrences of the disease in spruce and the abundance of the alternative host of the disease, bird-sherry (Prunus padus L.).

Infected shoots were encountered in a 17-year-old planted seedling stand of spruce. In this stand 8.4% of the seedlings were infected. The density of bird-cherry trees was in the stand higher than in the surrounding areas. The number of infected shoots was the greatest in those places where the density of bird-cherries was highest and already at a distance of some ten metres form the bird-cherry stands the degree of infection decreased considerably. The portion of infected cones in the whole material of this study was 19.5%.

The dependence of the frequency of disease on the abundance of bird-cherries at different distances from the spruce stand was studied by means of regression analysis. For this reason, the percentage infected cones were determined by sample plots and the abundance of bird-cherry trees from six zones (0–50, 50–100, 100–150, 150–200, 200–300, and 300–500 m) around each sample plot. The results showed that the dependence between the degree of infection of cones and the abundance of bird-cherry in the surroundings only reached the closest zone. There were also infected cones at greater distance, for instance, 200–300 m from the bird-cherries about 10% of the cones could be infected. Both the infected cones and shoots were longer than the healthy ones.

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  • Lilja, ORCID ID:E-mail:
article id 7511, category Article
Jukka Tyrväinen. (1995). Wood and fiber properties of Norway spruce and its suitability for thermomechanical pulping. Acta Forestalia Fennica no. 249 article id 7511. https://doi.org/10.14214/aff.7511

In the first part of the study, the selected wood and fiber properties were investigated in terms of their occurrence and variation in wood, as well as their relevance for thermomechanical pulping process and related end-products. It was concluded that the most important factors were the fiber dimensions, juvenile wood content, and in some cases, the content of heartwood being associated with extremely dry wood with low permeability in spruce. The following pulpwood assortments of which pulping potential was assumed to vary were formed: wood from regeneration cuttings, first-thinnings wood, and sawmill chips.

In the experimental part of the study, the average wood and fibre characteristics and their variation were determined for the raw material groups. Subsequently, each assortment – equalling about 1,500 m3 roundwood – was pulped separately for 24 h period. The properties of obtained newsgrade thermomechanical pulps were then determined.

Thermomechanical pulping (TMP) from sawmill chips had the highest proportion of long fibres, smallest proportion of fines, and had generally the coarsest and longest fibers. TMP from first-thinned wood was the opposite, whereas that from regeneration cuttings fell in between these two. High proportion of dry heartwood in wood originating from regeneration cuttings produced a slightly elevated shives content. However, no differences were found in pulp specific energy consumption. The obtained pulp tear index was clearly the best in TMP made from sawmill chips and poorest in pulp from first-thinned wood, which had generally inferior strength properties. No big differences in any of the strength properties were found between pulp from sawmill residual wood and regeneration cuttings. Pulp optical properties were superior in TMP from first-thinnings. No noticeable differences were found in sheet density, bulk, air permeance or roughness between the three pulps.

The most important wood quality factors were the fibre length, fibre cross-sectional dimensions and percentage juvenile wood. Differences found in the quality of TMP assortments suggest that they could be segregated and pulped separately to obtain specific product characteristics and to minimize unnecessary variation in the raw material and pulp quality.

  • Tyrväinen, ORCID ID:E-mail:
article id 7504, category Article
Alpo Luomajoki. (1993). Kuusen sopeutuminen Suomen ilmastoon hedekukkimisaikojen perusteella arvioituna. Acta Forestalia Fennica no. 242 article id 7504. https://doi.org/10.14214/aff.7504
English title: Climatic adaptation of Norway spruce (Picea abies (L.) Karsten) in Finland based on male flowering phenology.

Anthesis was studied at the canopy level in 10 Norway spruce (Picea abies (L.) H. Karst.) stands from 9 localities in Finland was studied in 1963-74. Distribution of pollen catches were compared with the normal Gaussian distribution. The basis for the timing studies was the 50% point of the anthesis-fitted normal distribution. Development was characterized in calendar days, in degree days (>5°C) and in period units. The count of each unit began on March 19 (included). Male flowering in Norway spruce stands was found to have more annual variation in quantity than in Scots pine (Pinus sylvestris L.) stands studied earlier.

Anthesis in spruce in Northern Finland occurred at a later date than in the south. The heat sums needed for anthesis varied latitudinally less in spruce than in pine. The variation of pollen catches in spruce increased towards north-west as in the case of Scots pine. In the unprocessed data, calendar days were found to be the most accurate forecast of anthesis in Norway spruce. Locally, the period unit could be a more accurate parameter for the stand average. However, on a calendar day basis, when annual deviations between expected and measured heat sums were converted to days, period units were narrowly superior to days.

The geographical correlations respected to timing of flowering, calculated against distances measured along simulated post-glacial micgation routes, were stronger than purely latitudinal correlations. Effects of the reinvasion of Norway spruce into Finland are thus still visible in spruce populations just as they were in Scots pine populations.

The proportion of the average annual heat sum needed for spruce anthesis grew rapidly north of a latitude of ca. 63° and the heat sum needed for anthesis decreased only slightly towards the timberline. In light of flowering phenology, it seems probable that north-western third of Finnish Norway spruce populations are incompletely adapted to the prevailing cold climate. A moderate warming of the climate would therefore be beneficial for Norway spruce. This accords roughly with the adaptive situation in Scots pine

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  • Luomajoki, ORCID ID:E-mail:
article id 7678, category Article
Lauri. Valsta. (1992). An optimization model for Norway spruce management based on individual-tree growth models. Acta Forestalia Fennica no. 232 article id 7678. https://doi.org/10.14214/aff.7678

A nonlinear programming algorithm was combined with two individual-tree growth simulators consisting of distance-independent diameter and height growth models and mortality models. Management questions that can be addressed by the optimization model include the timing, intensity and type of thinning, rotation age, and initial density. The results were calculated for Norway spruce (Picea abies (L.) H. Karst.) stands on Oxalis-Myrtillus site in Southern Finland, where the stand density after clearing of a seedling stand is about 2,000 trees/ha.

The optimum thinning programs were characterized by late first thinnings (at dominant height of 15–17 m) and relatively high growing stock levels. It was optimal to thin from above, unless mean annual increment was maximized instead of an economic objective. In most cases, the optimum number of thinnings was two or three. Compared to a no-thinning alternative, thinnings increased revenues by 15 –45% depending on the objective of stand management. Optimum rotation was strongly dependent on the interest rate.

Hooke and Jeeves’ direct search method was used for determining optimum solutions. The performance of the optimization algorithm was examined in terms of the number of functional evaluations and the equivalence of the objective function values of repeated optimizations.

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  • Valsta, 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.

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  • Kubin, ORCID ID:E-mail:
  • Kemppainen, ORCID ID:E-mail:
article id 7660, category Article
Heikki Hänninen. (1990). Modelling bud dormancy release in trees from cool and temperate regions. Acta Forestalia Fennica no. 213 article id 7660. https://doi.org/10.14214/aff.7660

The premises of several models obtained from literature on bud dormancy release in trees from cool and temperate regions differs from each other with respect to responses to air temperature during the rest period of the buds. The predicted timing of bud burst in natural conditions varied among the models, as did the prediction of the models for the outcome of a chilling experiment.

Experimental results with two-year old seedlings of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) did not agree with any of the models. The experimental results also deviated from abundand earlier findings, which also disagreed with any of the models. This finding suggests that Finnish provenances of Scots pine and Norway spruce differ from more southern provenances with respect to temperature regulation of bud dormancy release.

A synthesis model for the effects of air temperature on bud dormancy release in trees was developed on the basis of the previous models and the experimental results of both the present and previous studies. The synthesis model contains part of the original models as special cases. The parameters of the synthesis model represent several aspects of the bud dormancy release of trees that should be addressed separately with each species and provenance in experimental studies. Further aspects of dormancy release were discussed, in order to facilitate further development of the models.

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  • Hänninen, ORCID ID:E-mail:
article id 7656, category Article
Kari Leinonen, Matti Leikola, Antti Peltonen, Pentti Räsä­nen. (1989). Kuusen luontainen uudistaminen Pirkka-­Hämeen metsälautakunnassa. Acta Forestalia Fennica no. 209 article id 7656. https://doi.org/10.14214/aff.7656
English title: Natural regeneration of Norway spruce in Pirkka-Häme Forestry Board District, Southern Finland.

The aim of the present study was to evaluate and develop the use of natural regeneration of Norway spruce (Picea abies (L.) H. Karst.) in private forestry. The study was carried out using a line-plot survey with permanent circular sample plots. In total 40 regeneration sites were measured. The study includes results from three successive inventories: prior to the shelterwood cutting, in the summer after the cutting, and one year after the cutting. Regression and logistic regression analyses were used to construct models describing the effect of various factors on the restocking of the stands.

The standing volume prior to the shelterwood cutting was on average 236 m3/ha (ranging from 80 to 428 m3/ha) and after the cutting 120 m3/ha (39–220 m3/ha). The average number of stems per hectare decreased from 435 to 186. Prior to the shelterwood cutting 22% of the stands were satisfactorily restocked. After the cutting and one year later these percentages were 6 and 29%, respectively. Prior to the shelterwood cutting the number of acceptable seedlings was 1,440/ha, in the summer and year later 1,308/ha and 1,546/ha, respectively. Prior to the shelterwood cutting the characteristics of the mother stands did not correlate well with the number of seedlings. The change in the number of seedlings during the initial stage of shelterwood method depended on height of the seedling stand, amount of logging waste and number of germlings prior to the cutting. The risk to fail in regeneration was highest in the poorly restocked, sparse shelterwood stands, where a fast expansion of grass vegetation took place.

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  • Leinonen, ORCID ID:E-mail:
  • Leikola, ORCID ID:E-mail:
  • Peltonen, ORCID ID:E-mail:
  • Räsä­nen, ORCID ID:E-mail:
article id 7655, category Article
Leena Finér. (1989). Biomass and nutrient cycle in fertilized and unfertilized pine, mixed birch and pine and spruce stands on a drained mire. Acta Forestalia Fennica no. 208 article id 7655. https://doi.org/10.14214/aff.7655

At the beginning of the investigation period the total biomass of the Scots pine (Pinus sylvestris L.) stands on the ordinary sedge pine mire was 48 t/ha. The biomass of the mixed stands of Scots pine and birch (Betula pubescens Erhr.) on the herbrich sedge pine mire was 91 t/ha, out of which 60% was from pine. The biomass of the Norway spruce (Picea abies (L.) H. Karst.) on the Vaccinium-Myrtillus spruce mire was 148 t/ha. The average annual net increment of the stand biomass was 5.8 t/ha in the unfertilized pine stand and 6.7 t/ha in the NPK and micronutrient fertilized one during the six-year investigation period. The corresponding figures in the mixed stand were 7.2 t/ha and 7.6 t/ha. The net increment of the biomass in the unfertilized spruce stand was 6.9 t/ha and in the fertilized 8.4 t/ha. A considerable proportion of the net increment was lost to the ground as litter in all stands.

The nitrogen, phosphorus, potassium, magnesium, iron, manganese, zinc, copper and boron cycles were investigated. The annual nitrogen uptake from the soil was 26–42 kg/ha, that of phosphorus 2.5–3.4 kg/ha, potassium 4.5–12 kg/ha, calcium 12–29 kg/ha, magnesium 2–4 kg/ha, iron 1.4–6.6 kg/ha, manganese less than 2 kg/ha and the other nutrients only some grams. Only part of the fertilized nutrients was fixed in the stand.

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  • Finér, 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.

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  • Henttonen, ORCID ID:E-mail:
article id 7626, category Article
Aarne Nyyssönen, Risto Ojansuu. (1982). Metsikön puutavaralajirakenteen, arvon ja arvokasvun arviointi. Acta Forestalia Fennica no. 179 article id 7626. https://doi.org/10.14214/aff.7626
English title: Assessment of timber assortments, value and value increment of stands in Finland.

The paper is the final report of a study on the estimation of value increment and inherent variables of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands. The main aim was to obtain improved criteria for decision-making concerning the priority of stands for regeneration.

The construction of various estimation models and their reliability are discussed in detail. The study, together with some previous papers, has resulted in a system which on the basis of a number of easily assessed stand variables gives for the stands concerned the volume of stems, percentages of timber assortments, stumpage value, volume increment and value increment.

The following examples are given with regard to the practical application of the results, in addition to the determination of the relative maturity of stands: 1) The study of various trends in stand development; the comparison between the volume and value variables. 2) The estimation of timber assortments needed for a cutting budget, trees marked for felling etc. 3) The calculation of the value of forests.

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  • Nyyssönen, ORCID ID:E-mail:
  • Ojansuu, ORCID ID:E-mail:
article id 7618, category Article
Songkram Thammincha. (1981). Climatic variation in radial growth of Scots pine and Norway spruce and its importance in growth estimation. Acta Forestalia Fennica no. 171 article id 7618. https://doi.org/10.14214/aff.7618

Variation in the radial growth of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) was studied in 10 localities in Southern Finland. The aim of the study was to utilize the information on variation in the growth indices for growth estimation, and to evaluate the relative accuracy of growth estimation based on the data from increment boring, in comparison to other methods.

The climatic variation in periodic growth (5-year-period) in Southern Finland is about 11% of the normal level. The results suggest that the data from 10 localities can be used in the computation of the index series for Southern Finland and that the data from 10 relascope plots are required in the study of the climatic variation in tree growth in a given locality. The standard error of the estimate in actual growth estimation for past and future periods by the stand function method is about 23%, the errors of the method involving increment boring being 6% and 16% respectively in past and future growth estimation. The respective methods yield about 20% and 13% error in average growth estimation. With aid of the average growth indices for Southern Finland in local growth estimation the accuracy is distinctly improved, the error being equal to 12% only, while the accuracy in other cases is slightly improved.

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  • Thammincha, 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.

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  • Nyyssönen, ORCID ID:E-mail:
  • Mielikäinen, 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 7592, category Article
Anna-Maija Hallaksela. (1977). Kuusen kantojen mikrobilajisto. Acta Forestalia Fennica no. 158 article id 7592. https://doi.org/10.14214/aff.7592
English title: Microbial flora isolated from Norway spruce stumps.

The aim of the study was to identify the microbes which reach the cut surface of Norway spruce (Picea abies (L.) Karst.) stumps during the first year after felling by means of air born spores, determine their occurrence frequency and the combinations in which they occur, investigate the colour changes in the wood caused by microbes and identify the microbial species isolated from the sap- and heart-wood.

The material consisted of 360 spruce stumps. 300 of the stumps were innoculated with five different fungi (Phlebia gigantea, Botrytis cinerea, Gliocladium deliquescens, Trichoderma viride, Verticicladiella procera) in order to inhibit air-born attack by Heterobasidion annosum. 60 stumps were left untreated as controls.

The cultural characteristics of the following fungi isolated from the stumps have been described e.g.: Ceraceomerulius serpens, Chondrostereum purpureum, Cylindrobasidium evolvens, Peniophora pithya, Phlebia gigantea (Phlebiopsis gigantea) , P. subserialis, Sistotrema brinhmannii, Bjerkandera adusta, Coriolellus serialis, Trametes zonata, Armillariella mellea, Panellus mitis, Nectria fucheliana (microconidial-stage), Ascocoryne cylichnium (conidial-stage), Leptographium lundbergii, Acremonium butyri, Gliocladium deliquescens, Verticicladiella procera.

The proportion of Basidiomycotina fungi out of