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Articles containing the keyword 'damage'.

Category: Research article

article id 10134, category Research article
Matti Sirén, Jari Ala-Ilomäki, Harri Lindeman, Jori Uusitalo, Kalle E.K. Kiilo, Aura Salmivaara, Ari Ryynänen. (2019). Soil disturbance by cut-to-length machinery on mid-grained soils. Silva Fennica vol. 53 no. 2 article id 10134. https://doi.org/10.14214/sf.10134
Highlights: The number of machine passes, volumetric water content in the mineral soil and the depth of the organic layer were the controlling factors for rut formation; The harvester rut depth was a good predictor of the forwarder rut formation; Changes in the penetration resistance were highest at depths of 20–40 cm.

Factors affecting soil disturbance caused by harvester and forwarder were studied on mid-grained soils in Finland. Sample plots were harvested using a one-grip harvester. The harvester operator processed the trees outside the strip roads, and the remaining residues were removed to exclude the covering effect of residues. Thereafter, a loaded forwarder made up to 5 passes over the sample plots. The average rut depth after four machine passes was positively correlated to the volumetric water content at a depth of 0–10 cm in mineral soil, as well as the thickness of the organic layer and the harvester rut depth, and negatively correlated with penetration resistance at depths of both 0–20 cm and 5–40 cm. We present 5 models to predict forwarder rut depth. Four include the cumulative mass driven over a measurement point and combinations of penetration resistance, water content and the depth of organic layer. The fifth model includes harvester rut depth and the cumulative overpassed mass and provided the best fit. Changes in the penetration resistance (PR) were highest at depths of 20–40 cm. Increase in BD and VWC decreased PR, which increased with total overdriven mass. After four to five machine passes PR values started to stabilize.

  • Sirén, Natural Resources Institute Finland (Luke) c/o Aalto University, P.O. Box 15600, FI-00076 Aalto, Finland ORCID ID:E-mail: matti.siren@luke.fi (email)
  • Ala-Ilomäki, Natural Resources Institute Finland (Luke) c/o Aalto University, P.O. Box 15600, FI-00076 Aalto, Finland ORCID ID: http://orcid.org/0000-0002-6671-7624 E-mail: jari.ala-ilomaki@luke.fi
  • Lindeman, Natural Resources Institute Finland (Luke), Korkeakoulunkatu 7, FI-33720 Tampere, Finland ORCID ID:E-mail: harri.lindeman@luke.fi
  • Uusitalo, Natural Resources Institute Finland (Luke), Korkeakoulunkatu 7, FI-33720 Tampere, Finland ORCID ID: http://orcid.org/0000-0003-3793-1215 E-mail: jori.uusitalo@luke.fi
  • Kiilo, Versowood, Teollisuuskatu 1, FI-11130 Riihimäki, Finland ORCID ID:E-mail: kalle.kiilo@versowood.fi
  • Salmivaara, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00791 Helsinki, Finland ORCID ID:E-mail: aura.salmivaara@luke.fi
  • Ryynänen, Natural Resources Institute Finland (Luke), Kaironiementie 15, FI-39700 Parkano, Finland ORCID ID:E-mail: ari.ryynanen@luke.fi
article id 9918, category Research article
Ari Nikula, Vesa Nivala, Juho Matala, Kari Heliövaara. (2019). Modelling the effect of habitat composition and roads on the occurrence and number of moose damage at multiple scales. Silva Fennica vol. 53 no. 1 article id 9918. https://doi.org/10.14214/sf.9918
Highlights: The occurrence and number of moose damage were modelled with a zero-inflated count model; An admixture of mature forests within plantations increased the number of damage; Vicinity of inhabited areas and roads reduced damage; Plantations in landscapes with a large amount of pine-dominated thinning forests had less damage in Lapland; Damage risk assessment should include characteristics specific to each region.

We modelled the effect of habitat composition and roads on the number and occurrence of moose (Alces alces L.) damage in Ostrobothnia and Lapland using a zero-inflated count model. Models were developed for 1 km2, 25 km2 and 100 km2 landscapes consisting of equilateral rectangular grid cells. Count models predict the number of damage, i.e. the number of plantations and zero models the probability of a landscape being without damage for a given habitat composition. The number of moose damage in neighboring grid cells was a significant predictor in all models. The proportion of mature forest was the most frequent significant variable, and an increasing admixture of mature forests among plantations increased the number and occurrence of damage. The amount of all types of plantations was the second most common significant variable predicting increasing damage along with increasing amount of plantations. An increase in thinning forests as an admixture also increased damage in 1 km2 landscapes in both areas, whereas an increase in pine-dominated thinning forests in Lapland reduced the number of damage in 25 km2 landscapes. An increasing amount of inhabited areas in Ostrobothnia and the length of connecting roads in Lapland reduced the number of damage in 1 and 25 km2 landscapes. Differences in model variables between areas suggest that models of moose damage risk should be adjusted according to characteristics that are specific to the study area.

  • Nikula, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, Ounasjoentie 6, FI-96200 Rovaniemi, Finland ORCID ID:E-mail: ari.nikula@luke.fi (email)
  • Nivala, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, Ounasjoentie 6, FI-96200 Rovaniemi, Finland ORCID ID:E-mail: vesa.nivala@luke.fi
  • Matala, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: juho.matala@luke.fi
  • Heliövaara, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: kari.heliovaara@helsinki.fi
article id 9918, category Research article
Ari Nikula, Vesa Nivala, Juho Matala, Kari Heliövaara. (2019). Modelling the effect of habitat composition and roads on the occurrence and number of moose damage at multiple scales. Silva Fennica vol. 53 no. 1 article id 9918. https://doi.org/10.14214/sf.9918
Highlights: The occurrence and number of moose damage were modelled with a zero-inflated count model; An admixture of mature forests within plantations increased the number of damage; Vicinity of inhabited areas and roads reduced damage; Plantations in landscapes with a large amount of pine-dominated thinning forests had less damage in Lapland; Damage risk assessment should include characteristics specific to each region.

We modelled the effect of habitat composition and roads on the number and occurrence of moose (Alces alces L.) damage in Ostrobothnia and Lapland using a zero-inflated count model. Models were developed for 1 km2, 25 km2 and 100 km2 landscapes consisting of equilateral rectangular grid cells. Count models predict the number of damage, i.e. the number of plantations and zero models the probability of a landscape being without damage for a given habitat composition. The number of moose damage in neighboring grid cells was a significant predictor in all models. The proportion of mature forest was the most frequent significant variable, and an increasing admixture of mature forests among plantations increased the number and occurrence of damage. The amount of all types of plantations was the second most common significant variable predicting increasing damage along with increasing amount of plantations. An increase in thinning forests as an admixture also increased damage in 1 km2 landscapes in both areas, whereas an increase in pine-dominated thinning forests in Lapland reduced the number of damage in 25 km2 landscapes. An increasing amount of inhabited areas in Ostrobothnia and the length of connecting roads in Lapland reduced the number of damage in 1 and 25 km2 landscapes. Differences in model variables between areas suggest that models of moose damage risk should be adjusted according to characteristics that are specific to the study area.

  • Nikula, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, Ounasjoentie 6, FI-96200 Rovaniemi, Finland ORCID ID:E-mail: ari.nikula@luke.fi (email)
  • Nivala, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, Ounasjoentie 6, FI-96200 Rovaniemi, Finland ORCID ID:E-mail: vesa.nivala@luke.fi
  • Matala, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: juho.matala@luke.fi
  • Heliövaara, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: kari.heliovaara@helsinki.fi
article id 7751, category Research article
Göran Nordlander, Euan G. Mason, Karin Hjelm, Henrik Nordenhem, Claes Hellqvist. (2017). Influence of climate and forest management on damage risk by the pine weevil Hylobius abietis in northern Sweden. Silva Fennica vol. 51 no. 5 article id 7751. https://doi.org/10.14214/sf.7751
Highlights: Analysis of survey data from 292 reforestation areas in northern Sweden show that the probability of pine weevil damage can be predicted with a standard error of 0.12; Three variables are important in the optimal model: proportion of seedlings in mineral soil, age of clear-cut, and temperature sum; Temperature sum in the model can be adjusted to reflect future climate scenarios.

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

  • Nordlander, Swedish University of Agricultural Sciences (SLU), Department of Ecology, P.O. Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: Goran.Nordlander@slu.se
  • Mason, University of Canterbury, School of Forestry, Private Bag 4800, Christchurch 8140, New Zealand; Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID: http://orcid.org/0000-0001-9024-9106 E-mail: euan.mason@canterbury.ac.nz (email)
  • Hjelm, Skogforsk, The Forest Research Institute of Sweden, Ekebo 2250, SE-268 90 Svalöv, Sweden; Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: karin.hjelm@skogforsk.se
  • Nordenhem, Swedish University of Agricultural Sciences (SLU), Department of Ecology, P.O. Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: h.nordenhem@telia.com
  • Hellqvist, Swedish University of Agricultural Sciences (SLU), Department of Ecology, P.O. Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: Claes.Hellqvist@slu.se
article id 1741, category Research article
Seppo Nevalainen. (2017). Comparison of damage risks in even- and uneven-aged forestry in Finland. Silva Fennica vol. 51 no. 3 article id 1741. https://doi.org/10.14214/sf.1741
Highlights: Damage risks in two forest management regimes were estimated by means of a literature review and a questionnaire to Finnish forestry experts; Damage risks were usually estimated to be higher in even-aged than in uneven-aged management regimes; In some cases, however, damage risks may be higher in uneven-aged stands (root-rot infected Norway spruce stands and mechanical damage due to repeated thinnings).

The literature on the most prominent forest damage related to even-aged and uneven-aged forest management regimes was reviewed. A questionnaire to expert researchers was conducted to estimate risks in even-aged and uneven-aged forest management chains in Finland. There are only a few empirical comparisons of damage risks in even- and uneven-aged stands in the literature. The results from the expert survey showed that the damage risks were higher in even-aged management in Norway spruce and Scots pine. However, the variation in the risks between individual chains and between individual causes was high. The highest risks in Scots pine were caused by moose (in even-aged chains) and harvesting damage (in uneven-aged chains). In Norway spruce, root rot caused the highest risks in both even-aged and uneven-aged chains. The higher risks in even-aged forestry are largely due to the many associated practices which favour various types of damage. However, there are some important exceptions: the damage risks may be higher in some uneven-aged stands, especially in Norway spruce stands infected with root rot where the utilization of undergrowth or natural regeneration can be risky. Moreover, the repeated thinnings in uneven-aged stands may lead to increased mechanical damage.

  • Nevalainen, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: seppo.nevalainen@luke.fi (email)
article id 1693, category Research article
Olalla Díaz-Yáñez, Blas Mola-Yudego, José Ramón González-Olabarria. (2017). What variables make a forest stand vulnerable to browsing damage occurrence? Silva Fennica vol. 51 no. 2 article id 1693. https://doi.org/10.14214/sf.1693
Highlights: Stands more vulnerable to browsing damage are young with lower densities and dominated by birch, pine or mixed species; Stand size could play a role on forest susceptibility to browsing occurrence.

Ungulate browsing results in important damages on the forests, affecting their structure, composition and development. In the present paper, we examine the occurrence of browsing damage in Norwegian forests, using data provided by the National Forest Inventory along several consecutive measurements (entailing the period 1995–2014). A portfolio of variables describing the stand, site and silvicultural treatments are analyzed using classification trees to retrieve combinations related to browsing damage. Our results indicate that the most vulnerable forest stands are young with densities below 1400 trees ha–1 and dominated by birch, pine or mixed species. In addition, stand diversity and previous treatments (e.g. thinnings) increase the damage occurrence and other variables, like stand size, could play a role on forest susceptibility to browsing occurrence although the latter is based on weaker evidence. The methods and results of our study can be applied to implement management measures aiming at reducing the browsing damages of forests.

  • Díaz-Yáñez, School of Forest Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland ORCID ID: http://orcid.org/0000-0003-3829-5759 E-mail: olalla.diaz@gmail.com (email)
  • Mola-Yudego, Norwegian Institute of Bioenergy Research, P.O. Box, 115, 1431 Ås, Norway; School of Forest Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland ORCID ID: http://orcid.org/0000-0003-0286-0170 E-mail: blas.mola@uef.fi
  • González-Olabarria, Forest Sciences Centre of Catalonia (CTFC-CEMFOR), Ctra. de St. Llorenç de Morunys, km 2, 25280 Solsona, Spain ORCID ID: http://orcid.org/0000-0002-5040-712X E-mail: jr.gonzalez@ctfc.es
article id 1565, category Research article
Teija Ruuhola, Ari Nikula, Nivala Vesa, Seppo Nevalainen, Juho Matala. (2016). Effects of bedrock and surficial deposit composition on moose damage in young forest stands in Finnish Lapland. Silva Fennica vol. 50 no. 3 article id 1565. https://doi.org/10.14214/sf.1565
Highlights: The effect of bedrock and soil on moose damage in forest plantations were examined; Moose damage were concentrated in nutrient rich bedrock areas; Bedrock of damaged stands contained a higher proportion of mafic and alkaline rocks; Pine-dominated stands on fine grained fertile forest sites had the highest damage risk.

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

  • Ruuhola, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Yliopistokatu 6, FI-80101 Joensuu, Finland; University of Eastern Finland, Faculty of Science and Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: teija.ruuhola@uef.fi
  • Nikula, Natural Resources Institute Finland (Luke), Economics and Society, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: ari.nikula@luke.fi (email)
  • Vesa, Natural Resources Institute Finland (Luke), Economics and Society, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: vesa.nivala@luke.fi
  • Nevalainen, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Yliopistokatu 6, FI-80101 Joensuu, Finland ORCID ID:E-mail: seppo.nevalainen@luke.fi
  • Matala, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Yliopistokatu 6, FI-80101 Joensuu, Finland ORCID ID:E-mail: juho.matala@luke.fi
article id 1188, category Research article
Kristina Wallertz, Henrik Nordenhem, Göran Nordlander. (2014). Damage by the pine weevil Hylobius abietis to seedlings of two native and five introduced tree species in Sweden. Silva Fennica vol. 48 no. 4 article id 1188. https://doi.org/10.14214/sf.1188
Highlights: Both native and introduced confer species in Sweden can be highly susceptible to damage by the pine weevil; Douglas fir and Sitka spruce were generally the most damaged among six studied conifer species; The results highlight some of the risks in establishing exotic tree species for forest production.
There is increasing interest in using introduced species in Swedish forestry in response to climate change, but it is important to assess their resistance to native pests. Thus, we compared the extent of pine weevil feeding on two dominant native conifers, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.), the non-host deciduous broadleaf hybrid aspen (Populus × wettsteinii Hämet-Ahti) and four introduced conifers: Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), hybrid larch (Larix × marschlinsii Coaz), Sitka spruce (Picea sitchensis (Bong.) Carriére) and lodgepole pine (Pinus contorta Douglas ex Loudon). The extent of feeding damage on seedlings and its effect on their vitality were examined in a field study in south-central Sweden and a laboratory experiment, which gave largely consistent results. Generally, the species most heavily attacked by the pine weevil, in both experiments, were Douglas fir and Sitka spruce. In the field experiment pine weevils killed or severely damaged significantly higher proportions of Douglas fir and Sitka spruce seedlings (60%) than any other species except Norway spruce (49%). Among conifer seedlings the proportions of killed or severely damaged seedlings were lowest for Scots pine and hybrid larch (27%) and Lodgepole pine (36%). The results indicate that most conifer species planted on young clear-cuttings in Sweden need some kind of pine weevil protection, and the possibility that introducing new tree species might increase damage caused by pests must be considered. For instance, widespread use of hybrid aspen could reduce damage by pine weevils, but increase damage by other, untested pests or pathogens.
  • Wallertz, Unit for Field-based Forest Research, Swedish University of Agricultural Sciences (SLU), Asa Research Station, SE-36030 Lammhult, Sweden ORCID ID:E-mail: kristina.wallertz@slu.se (email)
  • Nordenhem, Department of Ecology, Swedish University of Agricultural Sciences (SLU), P.O. Box 7044, SE-75007 Uppsala, Sweden ORCID ID:E-mail: henrik.nordenhem@slu.se
  • Nordlander, Department of Ecology, Swedish University of Agricultural Sciences (SLU), P.O. Box 7044, SE-75007 Uppsala, Sweden ORCID ID:E-mail: goran.nordlander@slu.se
article id 1120, category Research article
Ilari Lehtonen, Petri Hoppula, Pentti Pirinen, Hilppa Gregow. (2014). Modelling crown snow loads in Finland: a comparison of two methods. Silva Fennica vol. 48 no. 3 article id 1120. https://doi.org/10.14214/sf.1120
Highlights: A new method to model crown snow loads is presented and compared with a previously published simpler method; The heaviest crown snow loads in Finland are found to typically occur in the eastern parts of the country; The relative importance of different snow load types varies between different regions of Finland.
The spatial occurrence of heavy crown snow loads in Finland between 1961 and 2010 is studied by using for the first time a model that classifies the snow load into four different types: rime, dry snow, wet snow and frozen snow. In producing this climatology, we used meteorological observations made at 29 locations across Finland. The model performance is evaluated against classified daily images of canopy snow cover and with the help of two short case studies. The results are further compared to those achieved with a simpler method used in previous studies. The heaviest crown snow loads are found to occur typically in eastern Finland. The new method reveals that this holds not only for the total snow loads but also for the different snow load types, although there are certain differences in their geographical occurrence. The greatest benefit achieved with the new method is the inclusion of rime accretion. The forests most prone to heavy riming are those located on tree-covered hills in northern Finland, but as the terrain elevation affects riming efficiency greatly, these small-scale variations in the snow load amounts could not be described in this study in great detail. Moreover, the results are more inaccurate in northern Finland where variations in the terrain elevation are greater than elsewhere. Otherwise, the largest uncertainties in this study are related to wind speed measurements and possibly partly because of that, we were not able to detect any significant trends in the crown snow-load amounts over the study period.
  • Lehtonen, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland ORCID ID:E-mail: ilari.lehtonen@fmi.fi (email)
  • Hoppula, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland ORCID ID:E-mail: petri.hoppula@fmi.fi
  • Pirinen, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland ORCID ID:E-mail: pentti.pirinen@fmi.fi
  • Gregow, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland ORCID ID:E-mail: hilppa.gregow@fmi.fi
article id 1003, category Research article
Raffaele Spinelli, Carolina Lombardini, Natascia Magagnotti. (2014). The effect of mechanization level and harvesting system on the thinning cost of Mediterranean softwood plantations. Silva Fennica vol. 48 no. 1 article id 1003. https://doi.org/10.14214/sf.1003
Highlights: Whole-tree harvesting is 40–50% cheaper than cut-to-length harvesting; Mechanization reduced thinning cost by a factor 4; Between 1.5 and 6% of the residual trees were damaged; Mechanized cut-to-length harvesting allows controlled biomass release; Mechanized whole-tree harvesting is the cheapest option for energy chip production.
The study compared motor-manual cut-to-length (CTL) harvesting, motor-manual whole-tree (WT) harvesting, mechanized CTL harvesting and mechanized WT harvesting as applied to the production of energy chips from the second thinning of Mediterranean pine plantations in flat terrain. Mechanization increased productivity between 6 and 20 times, depending on process step. It also allowed reducing thinning cost by a factor 4. Shifting from CTL to WT harvesting resulted in a reduction of harvesting cost between 40 and 50%. Fuel consumption was between 40 and 100% higher for CTL harvesting than for WT harvesting. Mechanization entailed a reduction of fuel consumption between 10 and 40%. Stand damage was generally low, between 1.5 and 6%. Mechanized CTL harvesting resulted in the lowest incidence of wounding, and the difference between mechanized CTL and manual WT harvesting was statistically significant. Soil compaction was absent or very small, depending on treatment. Mechanized thinning may produce larger increases of soil bulk density, compared to motor-manual thinning, but the difference is small, although significant. CTL harvesting leaves a larger amount of biomass on the soil, which relieves possible concerns about soil nutrient depletion. On the other hand, heavy residue loads may increase fire risk especially in sensitive Mediterranean environments.
  • Spinelli, CNR IVALSA,Via Madonna del Piano 10, Sesto Fiorentino (FI), Italy ORCID ID:E-mail: spinelli@ivalsa.cnr.it (email)
  • Lombardini, CNR IVALSA,Via Madonna del Piano 10, Sesto Fiorentino (FI), Italy ORCID ID:E-mail: lombardini@ivalsa.cnr.it
  • Magagnotti, CNR IVALSA,Via Biasi 75, S. Michele all’Adige (TN), Italy ORCID ID:E-mail: magagnotti@ivalsa.cnr.it
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 447, category Research article
Jim Kiser. (2011). Histochemical and geometric alterations of sapwood in coastal Douglas-fir following mechanical damage during commercial thinning. Silva Fennica vol. 45 no. 4 article id 447. https://doi.org/10.14214/sf.447
Histochemical and geometric alterations to sapwood in mechanically damaged Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco) trees were quantified 14 years after thinning. Discoloration and decay were measured in felled damaged and undamaged trees. Compartmentalized walls were identified and measured macroscopically. Sapwood to heartwood ratio was measured incrementally along the boles. Results showed a distinct reaction zone forming at the time of injury. Compartmentalized walls 1–3 were less distinct and heavily resinous streaking was evident in extant tissues, particularly in the axial direction. Post-damaged sapwood was burl-like for 4–6 years and tracheids contained resin-filled lumina. Damaged wood volumes were modeled by multiple regression. Wound depth, wound area, and diameter inside bark (DIB) accounted for 73% of the discolored volume (p = 0.02). DIB alone accounted for just over 55% of the response. Post-damaged sapwood averaged 15 mm (SE = 2.3 mm) greater in width on the side opposite the damage along the length of the boards. Wound area explained just over 65% of this response (p = 0.003). Sapwood area was not significantly different between damaged and control trees (p = 0.56). Results indicate that wounded Douglas-fir trees may slow conversion of sapwood to heartwood on the bole side opposite the wound, possibly as a response to maintain sapwood area necessary for physiological maintenance of the existing crown. About 19% of the lower bole volume in damaged trees was affected by discoloration and secondarily by structural changes. Reduction in value of the lower log can be as high as 19% by conventional bucking practices. Alternatives are presented to reduce the value loss to between 2.5% to 3.5%.
  • Kiser, P.O. Box 3729, Pagosa Springs, Colorado, USA ORCID ID:E-mail: jim.kiser@parelli.com (email)
article id 114, category Research article
Roy V. Rea. (2011). Impacts of moose (Alces alces) browsing on paper birch (Betula papyrifera) morphology and potential timber quality. Silva Fennica vol. 45 no. 2 article id 114. https://doi.org/10.14214/sf.114
Although moose browsing effects on the growth and morphology of birch are well studied, effects of moose browsing on potential timber quality of birch have received little attention. Here, an assessment was made of the impacts of moose (Alces alces L.) damage to Paper Birch (Betula papyrifera Marsh.) trees from a 20-year old clear cut area in a sub-boreal spruce forest within the Aleza Lake Research Forest, near Prince George, British Columbia, Canada. Specifically, differences in overall tree architecture and in the internal characteristics of trees that had been severely damaged and suppressed by moose winter browsing were compared to birch trees that had not been damaged by moose in this way and were considered free-to-grow. The average stem diameter, number of annular growth rings, and height of stem breaks made by moose on suppressed birches at the point of breakage was 17.9 ± 6.6 mm, 4.6 ± 1.2, and 141.8 ± 32.0 cm, respectively. Stem diameters and the heights above-the-ground of stem breaks made by moose during sequential breakage events were not significantly different (all p ≥ 0.05) from one another. Decay was significantly (all p ≤ 0.001) more extensive in trees where branches had been broken off by moose than in trees with no breaks or where breaks were from unknown agents. Suppressed birches were significantly (p = 0.048) more exposed (farther from their nearest tree neighbor) when compared to birches that were free-to-grow. The distance from birch trees to species-specific neighbors (of any species) did not differ (all p ≥ 0.05) between suppressed and free-to-grow birches. Suppressed birches damaged from intense browsing and stem breakage were significantly (≤ 0.001) farther away from other birches showing signs of slight to moderate browsing than free-to-grow birches were from similar conspecifics. Because moose appear to impact the potential wood quality of birch, forest managers should consider the impacts that browsing and stem breakage can have on birch timber where these trees co-occur with and are eaten by moose.
  • Rea, University of Northern British Columbia, 3333 University Way, Prince George, BC, Canada V2N 4Z9 ORCID ID:E-mail: reav@unbc.ca (email)
article id 32, category Research article
Susete Marques, Jordi Garcia-Gonzalo, José G. Borges, Brigite Botequim, M. Manuela Oliveira, José Tomé, Margarida Tomé. (2011). Developing post-fire Eucalyptus globulus stand damage and tree mortality models for enhanced forest planning in Portugal. Silva Fennica vol. 45 no. 1 article id 32. https://doi.org/10.14214/sf.32
Forest and fire management planning activities are carried out mostly independently of each other. This paper discusses research aiming at the development of methods and tools that can be used for enhanced integration of forest and fire management planning activities. Specifically, fire damage models were developed for Eucalyptus globulus Labill stands in Portugal. Models are based on easily measurable forest characteristics so that forest managers may predict post-fire mortality based on forest structure. For this purpose, biometric data and fire-damage descriptors from 2005/2006 National Forest Inventory plots and other sample plots within 2006, 2007 and 2008 fire areas were used. A three-step modelling strategy based on logistic regression methods was used. In the first step, a model was developed to predict whether mortality occurs after a wildfire in a eucalypt stand. In the second step the degree of damage caused by wildfires in stands where mortality occurs is quantified (i.e. percentage of mortality). In the third step this mortality is distributed among trees. Data from over 85 plots and 1648 trees were used for modeling purposes. The damage models show that relative damage increases with stand basal area. Tree level mortality models indicate that trees with high diameters, in dominant positions and located in regular stands are less prone to die when a wildfire occurs.
  • Marques, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail: smarques@isa.utl.pt (email)
  • Garcia-Gonzalo, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Borges, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Botequim, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Oliveira, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Tomé, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Tomé, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
article id 120, category Research article
Antti J. Lukkarinen, Seppo Ruotsalainen, Teijo Nikkanen, Heli Peltola. (2010). Survival, height growth and damages of Siberian (Larix sibirica Ledeb.) and Dahurian (Larix gmelinii Rupr.) larch provenances in field trials located in southern and northern Finland. Silva Fennica vol. 44 no. 5 article id 120. https://doi.org/10.14214/sf.120
The aim of this study was to analyse differences in the survival and height growth of, as well as damages to Siberian (Larix sibirica Ledeb.) and Dahurian (Larix gmelinii Rupr.) larch provenances over four growing seasons in field trials established in 2006 in southern (Punkaharju) and northern Finland (Kivalo). In this context, the study also investigated if the geographical and climatic conditions of the origin of the provenance could explain the differences between the provenances. The study material consisted of 20 Russian Siberian and Dahurian larch provenances and five seed sources from Finland (4) and Russia (1) as comparison lots. It was found that the Finnish seed sources of Siberian larch survived well in both the Kivalo and Punkaharju trials. Five northern latitude Russian provenances, of which one was Dahurian and the remainder were Siberian larches, had the highest survival in Kivalo. However, the differences observed in survival between provenances were only significant (p < 0.05) in Kivalo. Regardless of the trial, the differences, however, in height growth were significant and large between provenances. The southern Dahurian larches had a superior height growth in Punkaharju. The northern Dahurian larch provenance from Magadan (59°50′N, 150°40′E) had the largest height growth in Kivalo, among some northern Siberian larches. Damages were diverse, though Dahurian larches had less mammal damage than the Siberian larches. In general, the differences between provenances were not significant. Latitude and altitude best explained the differences between provenances, but also mean temperature, temperature sum and continentality index affected them (p < 0.05).
  • Lukkarinen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: antti.lukkarinen@pp.inet.fi (email)
  • Ruotsalainen, Finnish Forest Research Institute, FI-58450 Punkaharju, Finland ORCID ID:E-mail:
  • Nikkanen, Finnish Forest Research Institute, FI-58450 Punkaharju, Finland ORCID ID:E-mail:
  • Peltola, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
article id 138, category Research article
Santiago Martín-Alcón, José Ramón González-Olabarría, Lluís Coll. (2010). Wind and snow damage in the Pyrenees pine forests: effect of stand attributes and location. Silva Fennica vol. 44 no. 3 article id 138. https://doi.org/10.14214/sf.138
Wind and snow-induced damage have been analyzed at stand level for three pine forests in the Central-Eastern Pyrenees (Pinus nigra Arn. salzmanii, Pinus sylvestris L. and Pinus uncinata Ram.). Stand-level models have been then developed for the most affected two species, Pinus sylvestris L. and Pinus uncinata Ram., to describe damage severity. The models were based on data from national forest inventory plots. They included variables related to the spatial location and structure of the stands, being validated using a sub-set of the database (25% of the plots randomly selected). Mountain pine forests (Pinus uncinata Ram.) were the most heavily affected by wind and snow disturbances. For both mountain and Scots pine species, topographic exposure and the severity of the local storm regime had an important effect on the degree of damage. Stand’s resistance to wind and snow was found to be dependent on the combined effect of basal area and mean slenderness of the dominant trees. For a given slenderness ratio, damage increased strongly in lower-density stands, particularly in stands with basal areas below 15 m2/ha. Stand structure was particularly important to define the resistance of Scots pine stands, which presented a higher vulnerability to wind and snow under higher degree of even-agedness. The models presented in this study provide empirically-based information that can be used to implement silvicultural practices to minimize the risk of those forests to suffer wind and snow-related damages.
  • Martín-Alcón, Forest Technology Center of Catalonia, Solsona, Lleida, Spain ORCID ID:E-mail: santiago.martin@ctfc.es (email)
  • González-Olabarría, Forest Technology Center of Catalonia, Solsona, Lleida, Spain ORCID ID:E-mail:
  • Coll, Forest Technology Center of Catalonia, Solsona, Lleida, Spain ORCID ID:E-mail:
article id 138, category Research article
Santiago Martín-Alcón, José Ramón González-Olabarría, Lluís Coll. (2010). Wind and snow damage in the Pyrenees pine forests: effect of stand attributes and location. Silva Fennica vol. 44 no. 3 article id 138. https://doi.org/10.14214/sf.138
Wind and snow-induced damage have been analyzed at stand level for three pine forests in the Central-Eastern Pyrenees (Pinus nigra Arn. salzmanii, Pinus sylvestris L. and Pinus uncinata Ram.). Stand-level models have been then developed for the most affected two species, Pinus sylvestris L. and Pinus uncinata Ram., to describe damage severity. The models were based on data from national forest inventory plots. They included variables related to the spatial location and structure of the stands, being validated using a sub-set of the database (25% of the plots randomly selected). Mountain pine forests (Pinus uncinata Ram.) were the most heavily affected by wind and snow disturbances. For both mountain and Scots pine species, topographic exposure and the severity of the local storm regime had an important effect on the degree of damage. Stand’s resistance to wind and snow was found to be dependent on the combined effect of basal area and mean slenderness of the dominant trees. For a given slenderness ratio, damage increased strongly in lower-density stands, particularly in stands with basal areas below 15 m2/ha. Stand structure was particularly important to define the resistance of Scots pine stands, which presented a higher vulnerability to wind and snow under higher degree of even-agedness. The models presented in this study provide empirically-based information that can be used to implement silvicultural practices to minimize the risk of those forests to suffer wind and snow-related damages.
  • Martín-Alcón, Forest Technology Center of Catalonia, Solsona, Lleida, Spain ORCID ID:E-mail: santiago.martin@ctfc.es (email)
  • González-Olabarría, Forest Technology Center of Catalonia, Solsona, Lleida, Spain ORCID ID:E-mail:
  • Coll, Forest Technology Center of Catalonia, Solsona, Lleida, Spain ORCID ID:E-mail:
article id 165, category Research article
Yrjö Nuutinen, Kari Väätäinen, Antti Asikainen, Robert Prinz, Jaakko Heinonen. (2010). Operational efficiency and damage to sawlogs by feed rollers of the harvester head. Silva Fennica vol. 44 no. 1 article id 165. https://doi.org/10.14214/sf.165
In mechanical cutting, deep damage caused by feed rollers can reduce the yield of good quality timber for the sawmill and plywood industries. Additionally the feeding and energy efficiency of feed rollers are important for the profitability of harvester cutting. The objectives of this study were to compare the damages to sawlogs, as well as the time and fuel consumption of stem feeding with six different steel feed rollers during the processing of stems using a single grip harvester. This study tested two rollers with big spikes, two rollers with small spikes, one roller with studs in v-angle and one roller with adaptable steel plates in the ring of the roller. A highly detailed, and accurate processing and fuel consumption projection was recorded using the harvester’s automated data collector on a log and stem level. The roller adaptable plate averaged, for unbarked sawlogs, the lowest damages of 3.7 mm. While the damages of the roller with big spikes were the deepest with an average of 7.8 mm. For medium stems, volume of 0.35 m3, the range of differences between the maximum and minimum effective feeding time per roller was 6–19%, which would increase the effective time consumption of cutting by 1–3%. Corresponding differences in fuel consumption during total stem processing were in the range of 7–15%. According to this study it can be concluded that the traditional rollers with spikes were most effective in processing and fuel consumption, but at the same time they caused the deepest damages to the sawlogs. The roller type with adaptable steel plates was the most effective for small stems, additionally it also caused the least damage to the sawlogs.
  • Nuutinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: yrjo.nuutinen@metla.fi (email)
  • Väätäinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Asikainen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Prinz, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Heinonen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
article id 175, category Research article
Heikki Hänninen, Jaana Luoranen, Risto Rikala, Heikki Smolander. (2009). Late termination of freezer storage increases the risk of autumn frost damage to Norway spruce seedlings. Silva Fennica vol. 43 no. 5 article id 175. https://doi.org/10.14214/sf.175
Over the last few years it has become increasingly common in artificial forest regeneration to extend the planting period by using freezer-stored seedlings for early summer plantings. Developmentally, however, planted freezer-stored seedlings lag behind seedlings planted earlier in the spring. As freezer-stored seedlings also start hardening later, they are more susceptible to early autumn frosts, especially in years when the thermal growing season ends and the first autumn frosts come earlier than usual. By means of computer simulations with a simple temperature sum model and long-term air-temperature data from three locations in Finland, we examined the effect of the freezer-storage termination date on the risk of autumn frost damage to the seedlings. The long-term simulations revealed a drastic effect of year-to-year variation in the thermal conditions during the growing season on the occurrence of autumn frost damage. Such results provide crucial information complementary to those obtained in field experiments, which are always restricted to a relatively short time period. Together with earlier field data, the present results suggest that at an average regeneration site in central Finland, the planting of seedlings whose storage has terminated on 15 June and 22 June involve autumn frost damage every tenth and every fifth year, respectively. The sensitivity analysis revealed that the temperature sum requirement of maturation has a great effect on the risk of autumn frost damage, thus pinpointing the need for experimental studies addressing this ecophysiological trait of the seedlings.
  • Hänninen, Plant Ecophysiology and Climate Change Group (PECC), Department of Biological and Environmental Sciences, Box 65, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: heikki.hanninen@helsinki.fi (email)
  • Luoranen, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • 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 235, category Research article
Ari Nikula, Ville Hallikainen, Risto Jalkanen, Mikko Hyppönen, Kari Mäkitalo. (2008). Modelling the factors predisposing Scots pine to moose damage in artificially regenerated sapling stands in Finnish Lapland. Silva Fennica vol. 42 no. 4 article id 235. https://doi.org/10.14214/sf.235
Moose (Alces alces) damage in forest plantations have been at a high level in Finland in recent decades. Nowadays, moose is the most severe pest in Scots pine plantations also in Finnish Lapland. So far, despite the high level of damage and different bio-geographical conditions in Northern Finland, most of the moose-damage research has been carried out in Southern Finland. A number of research have also been performed to analyse factors affecting browsing but predictive models are rare. Data from 123 randomly selected and artificially regenerated pine plantations in Northern Finland were used in modelling the risk of moose browsing. The stands had been regenerated during 1984–1995. A total of 508 sample plots (range 2–8 plots per stand) were measured. Hierarchical logistic regression models with a random factor were constructed to predict the probability of leader-shoot browsing of pine on a plot. The number of planted pines and deciduous trees overtopping the pines were the most important predictors increasing the browsing probability. The results support earlier findings that deciduous trees overtopping or reaching the height of the pines should be cleaned from the immediate vicinity of the pines. Seedlings with a height ranging from 75 to 299 centimetres were more susceptible to browsing. Heavy soil scarification, such as ploughing or mounding, increased the browsing probability compared with lighter scarification methods. Soil type did not affect the browsing probability, but paludification decreased it. The within-stand variation in deciduous trees density and height should be taken into account in future moose browsing risk assessments. In Lapland, high moose damage risk areas are characterized by a low elevation and higher temperature sum.
  • Nikula, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: ari.nikula@metla.fi (email)
  • Hallikainen, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
  • Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
  • Hyppönen, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
  • Mäkitalo, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
article id 242, category Research article
Jyrki Hytönen, Paula Jylhä. (2008). Fifteen-year response of weed control intensity and seedling type on Norway spruce survival and growth on arable land. Silva Fennica vol. 42 no. 3 article id 242. https://doi.org/10.14214/sf.242
The effects of seedling type (2-year-old container seedlings vs. 4-year-old bare-rooted seedlings) and post-planting vegetation control intensity on the growth and survival of Norway spruce (Picea abies (L.) Karst.) seedlings were compared based on 15-year data from a field experiment established on arable land. Vegetation control treatments with terbuthylazine and glyphosate were carried out 1–3 times on successive years, either as overall or spot applications. The highest stand volumes were obtained with the combination of large bare-rooted seedlings and effective vegetation control. Volume of bare-rooted seedlings was greater than that of container seedlings in all treatments (e.g. on the control plots 9.5 m3/ha vs. 4.1 m3/ha). The best results were obtained with the most intensive weed control treatments (spot treatment repeated twice and overall application repeated three times). These treatments increased both bare-rooted and containerised seedlings’ survival by 33–40% units and their height, breast height diameter, and volume by 45–49%, 17–47%, and 249–279%, respectively. In terms of survival, the container seedlings, in due part to their smaller size, benefited from vegetation control more than the bare-rooted seedlings. Successive early summer frosts damaged the seedlings and significantly retarded their growth. The frequency of frost damage was not affected by vegetation control nor was it attributed to seedling type.
  • Hytönen, Finnish Forest Research Institute, Kannus Research Unit, P.O. Box 44, FI-69101, Kannus, Finland ORCID ID:E-mail: jyrki.hytonen@metla.fi (email)
  • Jylhä, Finnish Forest Research Institute, Kannus Research Unit, P.O. Box 44, FI-69101, Kannus, Finland ORCID ID:E-mail:
article id 254, category Research article
Johanna Joensuu, Kari Heliövaara, Eino Savolainen. (2008). Risk of bark beetle (Coleoptera, Scolytidae) damage in a spruce forest restoration area in central Finland. Silva Fennica vol. 42 no. 2 article id 254. https://doi.org/10.14214/sf.254
A beetle inventory using window traps was performed to examine the effect of forest restoration by artificial addition of dead wood on the abundance of beetles and to evaluate the risk of bark beetle damage in a forest restoration area. The number of beetle families was slightly increased, but no consistent differences were found in the abundance of families containing saproxylic Coleoptera between the restoration and control plots. The abundance and species number of bark beetles and longhorn beetles were significantly higher on the restoration plots. Ips typographus and Pityogenes chalcographus increased only slightly in abundance. In the regression models produced, the abundance of bark beetles was best explained by the volume of recently dead wood. However, the bark beetle species whose abundance increased most were secondary and the material also suggests an increase in the abundance of bark beetles’ natural enemies. The risk of bark beetle damage in the area is thus considered insignificant.
  • Joensuu, Dept. of Forest Ecology, University of Helsinki, Finland ORCID ID:E-mail: johanna.joensuu@metsanhoitajat.fi (email)
  • Heliövaara, Dept. of Forest Ecology, University of Helsinki, Finland ORCID ID:E-mail:
  • Savolainen, Kuopio Natural History Museum, Kuopio, Finland ORCID ID:E-mail:
article id 354, category Research article
Mervi Talvitie, Olli Leino, Markus Holopainen. (2006). Inventory of sparse forest populations using adaptive cluster sampling. Silva Fennica vol. 40 no. 1 article id 354. https://doi.org/10.14214/sf.354
In many studies, adaptive cluster sampling (ACS) proved to be a powerful tool for assessing rare clustered populations that are difficult to estimate by means of conventional sampling methods. During 2002 and 2003, severe drought-caused damage was observed in the park forests of the City of Helsinki, Finland, especially in barren site pine and spruce stands. The aim of the present study was to examine sampling and measurement methods for assessing drought damage by analysing the effectiveness of ACS compared with simple random sampling (SRS). Horvitz-Thompson and Hansen-Hurwitz estimators of the ACS method were used for estimating the population mean and variance of the variable of interest. ACS was considerably more effective than SRS in assessing rare clustered populations such as those resulting from drought damage. The variances in the ACS methods were significantly smaller and the inventory efficiency in the field better than in SRS.
  • Talvitie, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: mervi.talvitie@helsinki.fi (email)
  • Leino, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Holopainen, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
article id 351, category Research article
Jiaojun Zhu, Xiufen Li, Zugen Liu, Wei Cao, Yutaka Gonda, Takeshi Matsuzaki. (2006). Factors affecting the snow and wind induced damage of a montane secondary forest in northeastern China. Silva Fennica vol. 40 no. 1 article id 351. https://doi.org/10.14214/sf.351
In order to understand the processes of snow and wind induced damage in a natural montane, secondary forest in northeastern China, we examined the impacts of site conditions on the snow and wind damage; analyzed if the dominant tree species differed in their susceptibilities to the damage; and established the relationships between the characteristics of tree and stand and the damage. The results indicated that in regard to the topography factors, slope steepness and soil depth played a relatively important role for the damage. Damage ratios of all types combined were positively related with the composition of dominant tree species. The stand density was also important in determining resistance to the damage, i.e., the densely populated stand exhibited less overall damage ratios; however, the dominant tree species were commonly damaged easily by the snow and wind. Four damage modes found (uprooting, stem breakage, canopy damage and bending) were closely related to the stem taper (p < 0.05), and they could be ranked in following order: bending (92.0 ) > uprooting (85.3) > stem breakage (80.1) > canopy damage (65.0). In regard to differences in tree species’ susceptibilities to the damage, Betula costata exhibited the most uprooting, bending and overall damage ratios; while Quercus mongolica showed the highest breakage (both stem breakage and canopy damage) ratio, and Fraxinus mandshurica exhibited the least damage ratio (overall). The major six tree species could also be divided into two groups according to the overall damage ratios, i.e., more susceptible ones (B. costata, Ulmus laciniata and Q. mongolica), and less susceptible ones (F. mandshurica, Acer mono and Juglans mandshurica) to the snow and wind damage.
  • Zhu, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China ORCID ID:E-mail: zrms29@yahoo.com (email)
  • Li, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China; Graduate School of Chinese Academy of Sciences, Yuquan Road 19-A, Beijing, 100039, China ORCID ID:E-mail:
  • Liu, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China; Graduate School of Chinese Academy of Sciences, Yuquan Road 19-A, Beijing, 100039, China ORCID ID:E-mail:
  • Cao, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China ORCID ID:E-mail:
  • Gonda, Faculty of Agriculture, Niigata University, Ikarashi 2-8050, Niigata, 950-2181, Japan ORCID ID:E-mail:
  • Matsuzaki, Faculty of Agriculture, Niigata University, Ikarashi 2-8050, Niigata, 950-2181, Japan ORCID ID:E-mail:
article id 374, category Research article
Jyrki Hytönen, Paula Jylhä. (2005). Effects of competing vegetation and post-planting weed control on the mortality, growth and vole damages to Betula pendula planted on former agricultural land. Silva Fennica vol. 39 no. 3 article id 374. https://doi.org/10.14214/sf.374
Effects of competing vegetation and weed control methods (fibre board mulch, cover crop of clover, various herbicides) on the survival and growth of and vole damage to silver birch (Betula pendula Roth) were analysed based on data from a field experiment established in southern Finland. The cover percentage of competing vegetation and its shading effect were assessed, and seedling size and vitality were recorded several times during the 11-year research period. Mean seedling height and height increment decreased linearly with increasing vegetation cover. Seedling mortality started to significantly increase once the vegetation cover had reached the level of 60–80%. Herbicides significantly retarded increase of weed cover on the initially weedless areas for two to three years, and a cover crop promoted increase in cover percentage. Successful weed control with herbicides significantly increased seedling growth and survival. After 11 years, the average stem volume on the herbicide-treated plots (28.9 m3 ha–1) was 2.5-fold as compared to that of the control plots (11.6 m3 ha–1). Furthermore, seedling mortality on the control plots (21%) was almost 3.5-fold as compared to the seedling mortality on herbicide-treated plots (6%). Having a cover crop proved to be an ineffective weed control method both in terms of seedling growth and survival. The application of mulch had only a slight effect on height increment (0.6 m in 11 years), but on the other hand, it considerably decreased seedling mortality (control: 21%, mulch treatment: 1.5%). These differences were not, however, statistically significant. Small seedling size, high shading class, and high vegetation coverage percentage increased the risk of voles damaging the seedlings.
  • Hytönen, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FI-69101 Kannus, Finland ORCID ID:E-mail: jyrki.hytonen@metla.fi (email)
  • Jylhä, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FI-69101 Kannus, Finland ORCID ID:E-mail:
article id 604, category Research article
Dan Glöde, Ulf Sikström. (2001). Two felling methods in final cutting of shelterwood, single-grip harvester productivity and damage to the regeneration. Silva Fennica vol. 35 no. 1 article id 604. https://doi.org/10.14214/sf.604
In order to find an efficient and careful way of final-cutting shelterwoods, two felling methods, in a single-grip harvester system, were compared with respect to productivity and damage caused to the regeneration. The shelterwood (140–165 m3/ha) consisted of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) and the natural regeneration (9530–11 780 seedlings/ha) mostly of Norway spruce. Treatments were: (i) conventional felling on both sides of the harvester striproad, preferably in blanks of the regeneration; (ii) felling of the trees top-end first into the striproad using a method named “tossing the caber”. Both treatments included forwarding after felling. Conventional felling had a non-significantly higher productivity (27.4 m3/E15–h) and lower cost (25.9 SEK/m3) than tossing the caber (26.1 m3/E15–h and 27.2 SEK/m3). However, tossing the caber was significantly more efficient in the felling and processing of pine trees compared with conventional felling. The mean proportions of the disappeared and damaged seedlings were approximately 40% after both treatments. The logging-related damage to the regeneration decreased with increased distance to the striproad in the tossing the caber treatment but not in conventional felling. The conclusions were that there were no differences between the treatments regarding productivity, cost and total damage to the regeneration in mixed conifer shelterwoods but that tossing the caber could be a more productive method than conventional felling in pine dominated stands. Tossing the caber could also be beneficial at a regeneration height of 2–3 m since at this height the damage to the regeneration seems less than at conventional felling.
  • Glöde, SkogForsk, Uppsala Science Park, S-751 83 Uppsala, Sweden ORCID ID:E-mail: dan.glode@skogforsk.se (email)
  • Sikström, SkogForsk, Uppsala Science Park, S-751 83 Uppsala, Sweden ORCID ID:E-mail:
article id 637, category Research article
Hirofumi Kuboyama, Hiroyasu Oka. (2000). Climate risks and age-related damage probabilities – effects on the economically optimal rotation length for forest stand management in Japan. Silva Fennica vol. 34 no. 2 article id 637. https://doi.org/10.14214/sf.637
We estimated the damage probability according to age class and major climatic disasters based on ‘Statistical Yearbook of National Forest Insurance’ from 1960 to 1996. The probability of snow damage is high for young stands, then gradually decreases with age. On the other hand, the risk of wind damage gradually increases with age. Decisions about rotation age should be based on the distribution of damage probability with stand age. Risk of damage has two contradictory effects on the optimal rotation period; one is that the rotation-shortening effect caused by risk of damage around harvest age; another is the rotation-extending effect due to decrease of rent by the risk of damage through the raising period. Change of optimal rotation depends on the relative magnitude of these effects. We examine this by calculating land expectation value (LEV) using a simulation model with the empirical damage probability, price and cost. Change of the optimal rotation period obtained from the national average damage probability is not significant. However, the optimal rotation is shorter in high wind risk areas and is longer in high snow risk areas. It is because the damage probability for a mature stand is high in the case of wind and low in the case of snow. In addition, the extent of decrease in LEV is smaller for wind than for snow. The results of simulation based on empirical data confirm that the optimal rotation period can become either shorter or longer through incorporating risk in decision making, depending on the damage probability distribution with stand age.
  • Kuboyama, Forestry and Forest Products Research Institute Tohoku Center, Nabeyashiki 72, Shimo-Kuriyagawa, Morioka, Iwate, 020-0123 Japan ORCID ID:E-mail: kuboyama@ffpri-thk.affrc.go.jp (email)
  • Oka, Forestry and Forest Products Research Institute Tohoku Center, Nabeyashiki 72, Shimo-Kuriyagawa, Morioka, Iwate, 020-0123 Japan ORCID ID:E-mail:
article id 642, category Research article
Jonas Rönnberg. (2000). Logging operation damage to roots of clear-felled Picea abies and subsequent spore infection by Heterobasidion annosum. Silva Fennica vol. 34 no. 1 article id 642. https://doi.org/10.14214/sf.642
Two studies were carried out to examine the effects of clear-felling operations on stump roots of Norway spruce (Picea abies (L.) Karst.). In study I, the number of cases and the degree of damage to stump roots of Norway spruce were investigated on three clear-felled sites in northern and southern Sweden respectively. The cutting was done in winter or spring. A mean of 37% of the stumps had signs of root damage caused by clear-felling operations. Study II was carried out on two sites in southern and two sites in northern Sweden. The trees were clear-felled in June or July. The frequency of natural infection by Heterobasidion annosum (Fr.) Bref. through damaged roots was compared to infection through stump surfaces. The total area of damage on roots was 88% of the stump surface area. On average, 54% of the stumps were infected through the stump surface and 19% through locations of root damage. The root infections, however, were generally small in size as compared to stump surface infections. The study shows that damage to roots at clear-felling may be extensive, but this probably is not of great importance for the efficacy of stump treatment against H. annosum.
  • Rönnberg, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: jonas.ronnberg@ess.slu.se (email)
article id 648, category Research article
Sauli Härkönen. (1999). Forest damage caused by the Canadian beaver (Castor canadensis) in South Savo, Finland. Silva Fennica vol. 33 no. 4 article id 648. https://doi.org/10.14214/sf.648
The increasing Canadian beaver (Castor canadensis) population has caused forest damage in Finland. However, the occurrence, extent and importance of the damage have not been comprehensively studied. The field inspection was carried out in all of the beaver damage areas (n = 50) in the Anttola, Juva and Pieksämäki game management units in summer 1998. The characteristics of the damage areas, types of damage and the severity of the damage were examined. The size of the damage areas averaged 2.2 ha. The damage areas occurred on peatland forest more (p < 0.05) than expected. The dominant tree species were commercially valuable trees such as Scots pine (Pinus sylvestris) (33%), Norway spruce (Picea abies) (18%) and birches (Betula spp.) (47%). Birch occurred as dominant tree species more (p < 0.05) than expected. The proportion of older forest development classes was considerable. The most important type of damage was flooding (50%) caused by the damming activity of beavers. The trees were dead or dying in 18% of the damage areas. It was estimated that the ecosystem engineering performed by beavers was of no importance in 28% of the damage areas. Prevention of beaver damage has been carried out in 80% of the damage areas. In the study area, beaver numbers have steadily increased, although the number of beavers taken by hunting and the allowed hunting harvest have sharply increased. It is suggested that the methods used to prevent beaver damage should be improved and a compensation system should be provided by the state for the most damaged areas. Beavers can cause damage to commercial forestry, and this should be taken into account more effectively in the management plans made by the game management districts.
  • Härkönen, South Savo Game Management District, P.O. Box 14, FIN-51901 Juva, Finland ORCID ID:E-mail: sauli.harkonen@riistanhoitopiirico.inet.fi (email)
article id 648, category Research article
Sauli Härkönen. (1999). Forest damage caused by the Canadian beaver (Castor canadensis) in South Savo, Finland. Silva Fennica vol. 33 no. 4 article id 648. https://doi.org/10.14214/sf.648
The increasing Canadian beaver (Castor canadensis) population has caused forest damage in Finland. However, the occurrence, extent and importance of the damage have not been comprehensively studied. The field inspection was carried out in all of the beaver damage areas (n = 50) in the Anttola, Juva and Pieksämäki game management units in summer 1998. The characteristics of the damage areas, types of damage and the severity of the damage were examined. The size of the damage areas averaged 2.2 ha. The damage areas occurred on peatland forest more (p < 0.05) than expected. The dominant tree species were commercially valuable trees such as Scots pine (Pinus sylvestris) (33%), Norway spruce (Picea abies) (18%) and birches (Betula spp.) (47%). Birch occurred as dominant tree species more (p < 0.05) than expected. The proportion of older forest development classes was considerable. The most important type of damage was flooding (50%) caused by the damming activity of beavers. The trees were dead or dying in 18% of the damage areas. It was estimated that the ecosystem engineering performed by beavers was of no importance in 28% of the damage areas. Prevention of beaver damage has been carried out in 80% of the damage areas. In the study area, beaver numbers have steadily increased, although the number of beavers taken by hunting and the allowed hunting harvest have sharply increased. It is suggested that the methods used to prevent beaver damage should be improved and a compensation system should be provided by the state for the most damaged areas. Beavers can cause damage to commercial forestry, and this should be taken into account more effectively in the management plans made by the game management districts.
  • Härkönen, South Savo Game Management District, P.O. Box 14, FIN-51901 Juva, Finland ORCID ID:E-mail: sauli.harkonen@riistanhoitopiirico.inet.fi (email)
article id 648, category Research article
Sauli Härkönen. (1999). Forest damage caused by the Canadian beaver (Castor canadensis) in South Savo, Finland. Silva Fennica vol. 33 no. 4 article id 648. https://doi.org/10.14214/sf.648
The increasing Canadian beaver (Castor canadensis) population has caused forest damage in Finland. However, the occurrence, extent and importance of the damage have not been comprehensively studied. The field inspection was carried out in all of the beaver damage areas (n = 50) in the Anttola, Juva and Pieksämäki game management units in summer 1998. The characteristics of the damage areas, types of damage and the severity of the damage were examined. The size of the damage areas averaged 2.2 ha. The damage areas occurred on peatland forest more (p < 0.05) than expected. The dominant tree species were commercially valuable trees such as Scots pine (Pinus sylvestris) (33%), Norway spruce (Picea abies) (18%) and birches (Betula spp.) (47%). Birch occurred as dominant tree species more (p < 0.05) than expected. The proportion of older forest development classes was considerable. The most important type of damage was flooding (50%) caused by the damming activity of beavers. The trees were dead or dying in 18% of the damage areas. It was estimated that the ecosystem engineering performed by beavers was of no importance in 28% of the damage areas. Prevention of beaver damage has been carried out in 80% of the damage areas. In the study area, beaver numbers have steadily increased, although the number of beavers taken by hunting and the allowed hunting harvest have sharply increased. It is suggested that the methods used to prevent beaver damage should be improved and a compensation system should be provided by the state for the most damaged areas. Beavers can cause damage to commercial forestry, and this should be taken into account more effectively in the management plans made by the game management districts.
  • Härkönen, South Savo Game Management District, P.O. Box 14, FIN-51901 Juva, Finland ORCID ID:E-mail: sauli.harkonen@riistanhoitopiirico.inet.fi (email)
article id 692, category Research article
Eero Mattila. (1998). Use of satellite and field information in a forest damage survey of eastern Finnish Lapland in 1993. Silva Fennica vol. 32 no. 2 article id 692. https://doi.org/10.14214/sf.692
The study area consists of the Finnish part of a Landsat 5 TM image from 1990. Three independent field samples were measured during 1991–93 in the study area. The first sample was used to compile training areas for supervised maximum likelihood classification of the image. Classification accuracy was studied in the second sample. The spectral separability of the forest strata usable in practical forestry was poor. The extent of the damage area was estimated by the principle of stratified sampling. The estimate included considerable bias because the field sample had not been objectively selected from the image classes. The third field sample was measured as part of the National Forest Inventory of Finland. It is wholly objective, and about ten times larger than the two earlier field samples. The poor spectral separability of the forest strata was confirmed by the NFI sample. However, this sample could be used in stratified sampling with little or no bias in the estimation of the damage area estimate. 14 different damage types were separated according to specific damaging agent. A thematic map was produced which presents the spatial distribution of two damage-rich image classes. The study area comprises 18 300 sq.km, of which 38% were damaged. At first sight it would appear that the proportion of damaged forest has tripled in ten years. However, this is not the case because now special attention was paid to forest health in the field work. Despite this, it is possible that some damage caused by unfavourable climatic phenomena in the ’80s was still perceptible in 1993. No damage caused directly by air pollution has yet been verified in the study area.
  • Mattila, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail: eero.mattila@metla.fi (email)

Category: Research note

article id 1017, category Research note
Jeanette Edlund, Urban Bergsten, Hans Arvidsson. (2013). A forest machine bogie with a bearing capacity dependent contact area: acceleration and angular orientation when passing obstacles and drawbar pull force and free rolling resistance on firm ground. Silva Fennica vol. 47 no. 3 article id 1017. https://doi.org/10.14214/sf.1017
Highlights: The Long Tracked Bogie principle (LTB) has low contact area on firm ground with low load, it increases when higher traction force is needed and on softer soil; Free rolling resistance on firm ground was 60% of the value for a conventional bogie; LTB appears to pass wider ditches/cavities, more smoothly with lower pitch angle, than a conventional bogie.
The Long Tracked Bogie with contact area dependent on bearing capacity was compared to a conventional bogie. Two unloaded Vimek 608 forwarders with different bogies and with the traction from the front wheel removed were compared. Two high obstacles, 0.1 and 0.2 m high, respectively and 0.15 m in width, and two deep obstacles/ditches with a depth of 0.2 m and a width 1 and 1.5 m were used for tests. Towing tests on flat ground were done by connecting the machines to each other with a load cell in between.  There were no or small differences in acceleration when passing obstacles between the two types of bogie. LTB passed wider ditches/cavities with lower pitch angles (one bogie/side passing) and 0.2 m obstacles with higher roll angles than a conventional bogie. On firm ground, free rolling resistance of the LTB was about 60% of the resistance of the conventional bogie. The drawbar pull force for the LTB was indicated to be a few percentage units higher than for the conventional bogie when it was driving with a towed machine acting as a braking force. The LTB principle might yield opportunities to improve the way we construct bogies for forest machines. Even if the contact area is low on firm ground when the machine is running with low load, it increases when higher traction force is needed and on softer soil. Further field tests are needed to evaluate the LTB when used on soft ground and with higher load as well.
  • Edlund, Sveaskog AB, SE-941 86 Piteå, Sweden ORCID ID:E-mail: jeanette.edlund@sveaskog.se
  • Bergsten, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden ORCID ID:E-mail: urban.bergsten@slu.se (email)
  • Arvidsson, SMP Umeå, SE-904 03 Umeå, Sweden ORCID ID:E-mail: hans.arvidsson@smp.sp.se
article id 442, category Research note
Emil Modig, Bo Magnusson, Erik Valinger, Jonas Cedergren, Lars Lundqvist. (2012). Damage to residual stand caused by mechanized selection harvest in uneven-aged Picea abies dominated stands. Silva Fennica vol. 46 no. 2 article id 442. https://doi.org/10.14214/sf.442
Permanent field plots were established in two uneven-aged Norway spruce (Picea abies (L.) Karst) dominated stands in west-central Sweden. The objective was to quantify level and type of damage caused by harvesting and to quantify the difference between two treatments: T20) only skid road harvest (20 m distance between ca. 4 m wide roads), and T40) skid road harvest (40 m distance between ca. 4 m wide roads) combined with thinning between the roads. In T40, the goal was to harvest approximately the same standing volume as in T20. After harvest, two circular sample plots (radius 18 m, i.e. 1018 m2) were established at random locations within each treated area. All mechanical damage on the stem caused by harvest was measured and registered, including bark stripping larger than 15 cm2, stem broken or split, and tearing of branches causing damage on the stem. About 70–90 per cent of the damaged trees were smaller than 15 cm dbh. Very few trees larger than 25 cm dbh were damaged. In T20, more than 50 per cent of the damaged trees were located less than 5 m from the skid road, compared to less than 25 per cent for T40, in which more than 50 per cent of the damaged trees were located 5–10 m from the skid road. Creating only half the number of skid roads caused no more damage, and was probably more profitable because mean stem volume was about 1.5 times larger than in T20.
  • Modig, Statens fastighetsverk, Jokkmokk, Sweden ORCID ID:E-mail:
  • Magnusson, Skogsstyrelsen, Bräcke, Sweden ORCID ID:E-mail:
  • Valinger, Deparment of Forest Ecology and Management, SLU, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Cedergren, Mariehamn, Åland ORCID ID:E-mail:
  • Lundqvist, Deparment of Forest Ecology and Management, SLU, SE-901 83 Umeå, Sweden ORCID ID:E-mail: lars.lundqvist@slu.se (email)
article id 534, category Research note
Ilkka Leinonen, Heikki Hänninen. (2002). Adaptation of the timing of bud burst of Norway spruce to temperate and boreal climates. Silva Fennica vol. 36 no. 3 article id 534. https://doi.org/10.14214/sf.534
The adaptation of the annual cycle of development of boreal and temperate trees to climatic conditions has been seen as a result of stabilizing selection caused by two opposite driving forces of natural selection, i.e. the tolerance of unfavorable conditions during the frost exposed season (survival adaptation) and the effective use of growth resources during the growing season (capacity adaptation). In this study, two theories of the effects of climate on the adaptation of the timing of bud burst of trees were evaluated. This was done with computer simulations by applying a temperature sum model for predicting the timing of bud burst of different Norway spruce genotypes on the basis of air temperature data from various climatic conditions. High geographical variation in the temperature response of bud burst, typical for Norway spruce, was included in the theoretical analyses. The average timing of bud burst and the corresponding risk of occurrence of damaging frost during the susceptible period after bud burst were calculated for each genotype in each climate. Two contrasting theories of the stabilizing selection were evaluated, i.e. the overall adaptedness of each genotype was evaluated either 1) by assuming a fixed threshold for the risk of frost damage, or 2) by assuming a tradeoff between the risk of frost damage and the length of the growing season. The tradeoff assumption produced predictions of between provenance variation in bud burst which correspond more closely with empirical observations available in literature, compared to the fixed threshold assumption.
  • Leinonen, University of Oklahoma, Department of Botany and Microbiology, Norman, OK 73019, USA ORCID ID:E-mail: leinonen@ou.edu (email)
  • Hänninen, University of Helsinki, Department of Ecology and Systematics, FIN-00014 Helsinki, Finland ORCID ID:E-mail:

Category: Article

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.

The PDF includes a summary in German.

  • Nuorteva, ORCID ID:E-mail:
article id 7452, category Article
Olli Vaartaja. (1955). Factors causing mortality of tree seeds and succulent seedlings. Acta Forestalia Fennica vol. 62 no. 3 article id 7452. https://doi.org/10.14214/aff.7452

Germlings and small tree seedlings are exposed to extreme conditions in the forest floor. In this study the influence of climatic factors to seeds and seedlings were studied experimentally, and an attempt was made to estimate the importance of various factors in several sowing experiments in Finland.  

Seeds of Scots pine (Pinus sylvestris L.) were subjected to temperature variations which simulated those of exposed forest sites. The seeds lost some of their germinative capacity during the five-day treatments. Succulent seedlings died when subjected to immersion for 15 minutes at temperatures from 51.5 to 55 ºC. After a hardening pretreatments the seedlings tolerated 2-3 ºC higher temperatures. In artificial humus soil exposed to strong insolation for 15 minutes, temperatures in the range of 54-65 ºC proved to be critical for the seedlings. In natural conditions, also little lower temperatures may prove fatal. Exposure of succulent seedlings of Scots pine and Norway spruce (Picea abies (L.) Karst.) to insolation showed that most damage occurred on humus, quartz sand, and humus-sand mixture, due to rapid evaporation. Seeds of Scots pine, Norway spruce, Betula pendula and Betula pubescens tolerated poorly drought if germination had progressed to a 5–10 mm long radicle. Succulent seedlings tolerated 53-77 days long drought better in humus than in fine silty sand. Seedlings of Pinus sylvestris, Picea abies, Alnus incana and A. glutinosa tolerated cold variably. The developmental stage of the seedling affected cold resistance. Pine seeds sown in furrows germinated well after rain and the survival was high. Frost heaving, snail and insects caused some damages. Germination was lowest at the shallowest furrows. Sowing on natural surfaces gave poor results. Largest damages were caused by birds and ants. 

 The PDF includes a summary in Finnish.  

  • Vaartaja, 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.

The PDF includes a summary in German.

  • Kangas, 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.

The PDF includes a summary in German.

  • 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.

The PDF includes a summary in German.

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

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

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

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

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

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

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

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

The PDF includes a summary in German
  • Kangas, ORCID ID:E-mail:
article id 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.

The PDF includes a summary in German.

  • Multamäki, ORCID ID:E-mail:
article id 7340, category Article
P. S. Tikka. (1938). Puiden vikanaisuuksien vaikutuksesta hakkuutulokseen Perä-Pohjolan havumetsissä. Acta Forestalia Fennica vol. 46 no. 5 article id 7340. https://doi.org/10.14214/aff.7340
English title: The effect of injuries of the stems to amount of merchantable timber in the northernmost Finland.

The effect of different kinds of injuries in the amount of merchantable timber was studied in 57 sample plots in the northernmost Finland. Without any injuries the yield of timber would have been 72.3% in Scots pine (Pinus sylverstris L.) and 89.9% in Norway spruce (Picea abies (L.) H. Karst.). Butting, and removal of parts of the stems due to Injuries decreased the volume by 10.4% in pine and 13.5% in spruce. The main cause for butting of pine was fire wounds, and butt rot in spruce. Also pine blister rust (Peridermium pini and Cronartium flaccidum) causes injuries in Scots pine. The better the forest site type, the smaller is the timber discarded due to injuries. In pine 54% and in spruce 53% of the trees and were healthy. The forests in the northernmost Finland are over-mature which increase the occurrence of fire wounds and decay. Thus, forest fire control and the felling or thinning of over-mature stands will improve the quality of the timber in the long run.

The PDF includes a summary in German.

  • Tikka, 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 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 5639, category Article
Dimitris Athanassiadis. (1997). Residual stand damage following cut-to-length harvesting operations with a farm tractor in two conifer stands. Silva Fennica vol. 31 no. 4 article id 5639. https://doi.org/10.14214/sf.a8541

The objectives of this study were to record residual stand damage during harvesting operations and evaluate the influence of factors such as distance of the tree from the strip road, machine parts, operational phase, on the occurrence of tree wounds. The machine was a farm tractor equipped with a crane mounted on the front axle and a single grip harvester head. The study was carried out in two stands located in Southeast Sweden. Stand 1 was a 30-year-old Norway spruce (Picea abies (L.) H. Karst.) plantation on an afforested pasture while stand 2 was a 90-year-old mixed stand of Norway spruce, Scots pine (Pinus sylvestris L.), birch (Betula pendula Roth) and aspen (Populus tremula L.).

The mean damage percentage was 6.3% for the first stand and 6.5% for the second stand. Sixty-five percent of the wounds were less than 50 cm2, with 91% of the damage occurring on the stem and 91% of the damage on or below the root collar. Sixty-six percent of the wounds produced by the stem under processing or by the harvesting head while only 10% of the wounds were produced by the tractor wheel. Damaged trees were distributed evenly in the crane reach zone. Significant differences were found between rut depths after one, two, four and six passes of the tractor in stand 1.

  • Athanassiadis, ORCID ID:E-mail:
article id 5618, category Article
Marja-Leena Nykänen, Marianne Broadgate, Seppo Kellomäki, Heli Peltola, Christopher Quine. (1997). Factors affecting snow damage of trees with particular reference to European conditions. Silva Fennica vol. 31 no. 2 article id 5618. https://doi.org/10.14214/sf.a8519

Within the European Community snow damage affects an estimated 4 million m3 of timber every year, causing significant economic losses to forest owners. In Northern Europe, for example, the occurrence of snow damage has increased over the last few decades mainly due to the increase in total growing stock. The most common form of damage is stem breakage, but trees can also be bent or uprooted. Trees suffering snow damage are also more prone to consequential damage through insect or fungal attacks.

Snow accumulation on trees is strongly dependent upon weather and climatological conditions. Temperature influences the moisture content of snow and therefore the degree to which it can accumulate on branches. Wind can cause snow to be shed, but can also lead to large accumulations of wet snow, rime or freezing rain. Wet snow is most likely in late autumn or early spring. Geographic location and topography influence the occurrence of damaging forms of snow, and coastal locations and moderate to high elevations experience large accumulations. Slope plays a less important role and the evidence on the role of aspect is contradictory. The occurrence of damaging events can vary from every winter to once every 10 years or so depending upon regional climatology. In the future, assuming global warming in northern latitudes, the risk of snow damage could increase, because the relative occurrence of snowfall near temperatures of zero could increase.

The severity of snow damage is related to tree characteristics. Stem taper and crown characteristics are the most important factors controlling the stability of trees. Slightly tapering stems, asymmetric crowns, and rigid horizontal branching are all associated with high risk. However, the evidence on species differences is less clear due to the interaction with location. Management of forests can alter risk through choice of regeneration, tending, thinning and rotation. However, quantification and comparison of the absolute effect of these measures is not yet possible. An integrated risk model is required to allow the various locational and silvicultural factors to be assessed. Plans are presented to construct such a model, and gaps in knowledge are highlighted.

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

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

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

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

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

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

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

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

  • Kaitera, ORCID ID:E-mail:
  • Jalkanen, ORCID ID:E-mail:
article id 5523, category Article
Reijo Solantie. (1993). Snow and soil frost in Finnish forests. Silva Fennica vol. 27 no. 4 article id 5523. https://doi.org/10.14214/sf.a15684

Abundant snowfalls and thick snow cover influence forest ecology mainly in two ways. Snow loading increases the number of damaged stems, which increases the amount of decay in stems, in its turn important for many animals. Second, the ground remains unfrozen under the snow cover, which is of crucial importance for many perennial species of ground vegetation. These winter phenomena also have influenced the early Finnish culture as man in his everyday life in the wilderness was in close contact with nature. In this paper, ecological interactions between snow conditions, forest flora, fauna and early culture are discussed mainly with reference to the province of Uusimaa in Southern Finland.

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

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

The PDF includes an abstract in Finnish.

  • Hänninen, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Laitinen, ORCID ID:E-mail:
  • Pajari, ORCID ID:E-mail:
  • Repo, ORCID ID:E-mail:
article id 5507, category Article
John L. Innes. (1993). Methods to estimate forest health. Silva Fennica vol. 27 no. 2 article id 5507. https://doi.org/10.14214/sf.a15668

A range of different indices are available for assessing the health of trees in forests. An even larger range can be used for the assessment of the health of forest ecosystems. Most studies made in connection with ”forest decline” and the impact of air pollution and other environmental stresses on forests have concentrated on the assessment of crown transparency and crown discoloration in individual trees. These are non-specific indicators which are now known to be sometimes of relatively little value when determining the health of a forest ecosystem. Numerous problems exist with both, and the standardisation of assessments between and even within countries has not been achieved. Consequently, studies claiming to compare ”defoliation” between different countries cannot be substantiated. The emphasis on crown transparency and crown discoloration has resulted in the neglect of a number of other indices that could be of considerable value. These include a variety of visual measures of crown condition and also several non-visual bioindicators. Some of these techniques are objective, reducing the present reliance on observed standardization. A large number of potential techniques are currently at the research stage and have yet to be adequately tested in field trials. This represent an area where a substantial amount of further research is required.

  • Innes, ORCID ID:E-mail:
article id 5486, category Article
Kari Löyttyniemi, Risto Heikkilä, Seppo Repo. (1992). Pine tar in preventing moose browsing. Silva Fennica vol. 26 no. 3 article id 5486. https://doi.org/10.14214/sf.a15647

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

The PDF includes an abstract in Finnish.

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

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

The PDF includes an abstract in Finnish.

  • Heikkilä, ORCID ID:E-mail:
  • Löyttyniemi, ORCID ID:E-mail:
article id 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.

The PDF includes an abstract in Finnish

  • Långström, ORCID ID:E-mail:
  • Hellqvist, 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.

The PDF includes an abstract in Finnish

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

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

The PDF includes an abstract in Finnish.

  • Heikkilä, ORCID ID:E-mail:
article id 5427, category Article
Matti Nuorteva. (1990). Salama puustokuolemien aiheuttajana. Silva Fennica vol. 24 no. 2 article id 5427. https://doi.org/10.14214/sf.a15581
English title: Lightning as a cause of death of tree groups.
English keywords: lightning; forest damage

The writer reports in this discussion article of four stands in Finland that have died due to a bolt of lightning. A death of a group of trees because of lightning has been relatively uncommon for the forest professionals. The trees may not have no lightning marks. The four sites are presented in detail. Characteristic for this type of death of trees is, for instance, that trees have died within a circular area (of usually 30 m of diameter), only conifers have died, trees die from the top down, sometimes marks can be found in trees in the centre of the area, and under the bark may be brown patches or stripes.

  • Nuorteva, ORCID ID:E-mail:
article id 5393, category Article
Erkki Annila. (1989). Metsien kunto ja bioottiset tuhonaiheuttajat. Silva Fennica vol. 23 no. 4 article id 5393. https://doi.org/10.14214/sf.a15551
English title: Condition of forests and biotic damages .

This review discusses whether forests are affected by biotic damages due to present or future environmental disturbances, and do environmental threats, such as air pollution and climatic change, weaken the condition of forest in a way that makes them vulnerable to damages by fungi and insect. The defence mechanisms of trees and factors affecting the development of an outbreak are described. Finally, the ways that air pollution and climatic change may affect biotic damages are discussed. 

  • Annila, 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.

The PDF includes an abstract in Finnish.

  • Rostad, 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.

The PDF includes an abstract in Finnish.

  • Christersson, ORCID ID:E-mail:
  • Fircks, ORCID ID:E-mail:
article id 5350, category Article
Heikki Hänninen, Paavo Pelkonen. (1988). Frost hardiness and over-wintering of forest trees. Silva Fennica vol. 22 no. 3 article id 5350. https://doi.org/10.14214/sf.a15507

This issue of Silva Fennica consists of eight articles, which are based on a co-nordic conference ”Frost hardiness and over-wintering in forest tree seedlings”, held in Joensuu, Finland, during December 1–3, 1986. The whole annual cycle of the trees is considered. Emphasis is given on methods for the study of frost hardiness, genetic variation in frost hardiness, nitrogen metabolism, bud dormancy release, and joint effect of natural and anthropogenic stress factors in the winter damage of forest trees. Practical implications for tree breeding and nursery management are discussed.

The PDF includes an abstract in Finnish.

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

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

The PDF includes an abstract in Finnish.

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

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

The PDF includes an abstract in Finnish.

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

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

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

The PDF includes a summary in Finnish.

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

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

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

The PDF includes a summary in Finnish.

  • Löyttyniemi, ORCID ID:E-mail:
article id 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 5218, category Article
Jouni Suoheimo. (1984). Isokorvakärsäkkään aikuisten esiintyminen ja merkitys männyn luontaiselle uudistamiselle Pohjois-Lapissa. Silva Fennica vol. 18 no. 3 article id 5218. https://doi.org/10.14214/sf.a15397
English title: The occurrence of Otiorrhynchus nodosus and its significance for the natural regeneration of Scots pine in Lapland.

The aim of the present study was to survey the occurrence of Otiorrhynchus nodosus Müller weevils and their significance for the natural regeneration of Scots pine (Pinus sylvestris L.). The study was carried out during summer 1982 at Inari in northern Lapland.

There were two sample plots, one situated in a Scots pine seed-tree area and the other, the control sample plot, in an area with a coverage of mountain birch (Betula pubescens subsp. tortuosa, now subsp. czerepanovii). A total of 177 Otiorhynchus weevils were caught. Movement of the weevils reached its climax in July. There were 86% more individuals in the seed-tree area than in the mountain birch area. No damage to the pine germlings or seedlings was not observed, although the situation could be different during the peaks of the veewil populations.

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  • Suoheimo, ORCID ID:E-mail:
article id 5218, category Article
Jouni Suoheimo. (1984). Isokorvakärsäkkään aikuisten esiintyminen ja merkitys männyn luontaiselle uudistamiselle Pohjois-Lapissa. Silva Fennica vol. 18 no. 3 article id 5218. https://doi.org/10.14214/sf.a15397
English title: The occurrence of Otiorrhynchus nodosus and its significance for the natural regeneration of Scots pine in Lapland.

The aim of the present study was to survey the occurrence of Otiorrhynchus nodosus Müller weevils and their significance for the natural regeneration of Scots pine (Pinus sylvestris L.). The study was carried out during summer 1982 at Inari in northern Lapland.

There were two sample plots, one situated in a Scots pine seed-tree area and the other, the control sample plot, in an area with a coverage of mountain birch (Betula pubescens subsp. tortuosa, now subsp. czerepanovii). A total of 177 Otiorhynchus weevils were caught. Movement of the weevils reached its climax in July. There were 86% more individuals in the seed-tree area than in the mountain birch area. No damage to the pine germlings or seedlings was not observed, although the situation could be different during the peaks of the veewil populations.

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  • Suoheimo, ORCID ID:E-mail:
article id 5213, category Article
Bo Långström. (1984). Windthrown Scots pines as brood material for Tomicus piniperda and T. minor. Silva Fennica vol. 18 no. 2 article id 5213. https://doi.org/10.14214/sf.a15392

In the 1980 and 1981, windthrown and felled Scots pine (Pinus sylvestris L.) were examined at 8 localities in Sweden. The number and length of egg galleries as well as the number of exit holes of Tomicus piniperda (L.) and T. minor (Hart.) were recorded on sample sections (30 m in length) distributed at 3 m intervals on the 37 fallen pine stems, which were successfully colonized by the beetles. In addition, 78 uprooted pines were surveyed in 6 localities. Most trees were attacked by T. piniperda, but only a few by T. minor. Successful colonization often resulted in the production of several thousand beetles per tree, the maximum being approximately 1,800. The attack density of T. piniperda seldom exceeded 200 egg galleries/m3 bark area, and the brood production usually remained below 1,000 beetles/m3. Much higher figures were obtained or T. minor. In T. piniperda, the rate of reproduction (i.e. the number of exit holes /egg gallery) decreased rapidly with increasing attack density, whereas T. minor seemed to be less sensitive to intraspecific competition.

The PDF includes a summary in Finnish.

  • Långström, ORCID ID:E-mail:
article id 5213, category Article
Bo Långström. (1984). Windthrown Scots pines as brood material for Tomicus piniperda and T. minor. Silva Fennica vol. 18 no. 2 article id 5213. https://doi.org/10.14214/sf.a15392

In the 1980 and 1981, windthrown and felled Scots pine (Pinus sylvestris L.) were examined at 8 localities in Sweden. The number and length of egg galleries as well as the number of exit holes of Tomicus piniperda (L.) and T. minor (Hart.) were recorded on sample sections (30 m in length) distributed at 3 m intervals on the 37 fallen pine stems, which were successfully colonized by the beetles. In addition, 78 uprooted pines were surveyed in 6 localities. Most trees were attacked by T. piniperda, but only a few by T. minor. Successful colonization often resulted in the production of several thousand beetles per tree, the maximum being approximately 1,800. The attack density of T. piniperda seldom exceeded 200 egg galleries/m3 bark area, and the brood production usually remained below 1,000 beetles/m3. Much higher figures were obtained or T. minor. In T. piniperda, the rate of reproduction (i.e. the number of exit holes /egg gallery) decreased rapidly with increasing attack density, whereas T. minor seemed to be less sensitive to intraspecific competition.

The PDF includes a summary in Finnish.

  • Långström, ORCID ID:E-mail:
article id 5202, category Article
Kari Löyttyniemi. (1983). Flight periods of some birch timber insects. Silva Fennica vol. 17 no. 4 article id 5202. https://doi.org/10.14214/sf.a15185

Flight periods of insects breeding on birch (Betula sp.) timber were observed by means of window flight traps baited with freshly cut birch logs in five locations in Finland from 1972 to 1976. Only few species were caught during the study. In general, these species were on the wing during midsummer, although flight periods of some of them were relatively long. Scolytus ratzeburgi Jans. caused harmful staining of wood within a month from attack, but the damage by the wood-boring pests remained negligible throughout the first storage summer.

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  • Löyttyniemi, ORCID ID:E-mail:
article id 5197, category Article
Kari Heliövaara, Erkki Annila, Eero Terho. (1983). Effect of nitrogen fertilization and insecticides on the population density of pine bark bug, Aradus cinnamomeus (Heteroptera, Aradidae). Silva Fennica vol. 17 no. 4 article id 5197. https://doi.org/10.14214/sf.a15180

The effect of nitrogen fertilization and two insecticides on the occurrence of the plant pine bark bug, Aradus cinnamomeus Panzer, was investigated in a young Scots pine (Pinus sylvestris L.) stand in Southern Finland. Three years after the treatment the bug density was lowest in the trees treated with lindane or dimethoate. However, in spite of the increasing height growth of the trees, they did not grow significantly faster than the control trees. Nitrogen fertilization increased both bug density and the height growth of the trees. Thus, the value of nitrogen fertilization against Aradus cinnamomeus remains obscure.

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  • Heliövaara, ORCID ID:E-mail:
  • Annila, ORCID ID:E-mail:
  • Terho, ORCID ID:E-mail:
article id 5195, category Article
Matti Rousi. (1983). Susceptibility of pine to mammalian herbivores in northern Finland. Silva Fennica vol. 17 no. 4 article id 5195. https://doi.org/10.14214/sf.a15178

An inventory of Scots pine (Pinus sylvestris L.) graft collection in Kolari (67°15’ N, 23°45’ S) showed that severe damage by arctic hare (Lepus timidus L.), root and bank vole (Microtus oeconomus Pallas and M. agrestis L.) and moose (Alces alces L.) was done to grafts in size and in rather poor condition. Furthermore, the damage by arctic hare was dependent on the dry matter content of the needles. Another inventory in a fertilization experiment in a pine pole-stage forest showed that nitrogen fertilization increased the damage by arctic hare. On the basis of the present results, an assumption was made that the formation of repellent substances against herbivorous mammals is connected with wintering process of northern pines.

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  • Rousi, ORCID ID:E-mail:
article id 5195, category Article
Matti Rousi. (1983). Susceptibility of pine to mammalian herbivores in northern Finland. Silva Fennica vol. 17 no. 4 article id 5195. https://doi.org/10.14214/sf.a15178

An inventory of Scots pine (Pinus sylvestris L.) graft collection in Kolari (67°15’ N, 23°45’ S) showed that severe damage by arctic hare (Lepus timidus L.), root and bank vole (Microtus oeconomus Pallas and M. agrestis L.) and moose (Alces alces L.) was done to grafts in size and in rather poor condition. Furthermore, the damage by arctic hare was dependent on the dry matter content of the needles. Another inventory in a fertilization experiment in a pine pole-stage forest showed that nitrogen fertilization increased the damage by arctic hare. On the basis of the present results, an assumption was made that the formation of repellent substances against herbivorous mammals is connected with wintering process of northern pines.

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  • Rousi, ORCID ID:E-mail:
article id 5177, category Article
Kari Löyttyniemi. (1983). Preliminary testing of the resistance of Finnish softwood timbers to Macrotermitinae termites. Silva Fennica vol. 17 no. 1 article id 5177. https://doi.org/10.14214/sf.a15092

The resistance of Finnish softwood timbers to Macrotermitinae termites was tentatively tested under tropical conditions in Zambia using a field microtest method. Picea abies (L.) H. Karst. and Larix sibirica L. sapwood and heartwood, as well as Pinus sylvestris L. sapwood, and the sapwood of the locally grown Pinus kesiya, exhibited no natural termite resistance. On the other hand, Juniperus communis heartwood appeared to be virtually immune and the heartwood of P. Sylvestris had some resistance. There were also some differences in the resistance of the heartwood of the different P. Sylvestris individuals tested, which was correlated with the width of the annual rings in the wood samples. The termite species involved were Microtermes sp. and Odontotermes sp. The possibilities of using different types of Finnish softwood timber in the regions in the tropics where there is a risk of termite damage is discussed.

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  • Löyttyniemi, ORCID ID:E-mail:
article id 5168, category Article
Kari Heliövaara. (1982). The pine bark bug, Aradus cinnamomeus (Heteroptera, Aradidae) and the height growth rate of young Scots pines. Silva Fennica vol. 16 no. 4 article id 5168. https://doi.org/10.14214/sf.a15083

Relationships between densities of pine bark bug, Aradus cinnamomeus Panzer and the height growth of young Scots pine (Pinus sylvestris L.) were studied in several habitats, including a highly infested area in Southern Finland. The slower the growth of the pines was, the greater was the height up to which bugs were found. On the average, maximum bug density was noted at a height corresponding to a fifth of the height of the tree. In stands restocked by natural generation, the greatest bug densities were noted in pines about three metres high and over twenty years old. Bug densities in trees whose height growth had been decelerating for five years were twice those in trees whose growth was accelerating. A significant negative correlation was found between the bug density and the last-year height increment.

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  • Heliövaara, ORCID ID:E-mail:
article id 5146, category Article
J. N. Cape, D. Fowler. (1981). Changes in epicuticular wax of Pinus sylvestris exposed to polluted air. Silva Fennica vol. 15 no. 4 article id 5146. https://doi.org/10.14214/sf.a15373

Scanning Electron Microscopy was used to study structural changes in epicuticular vax of Pinus sylvestris L. with time. Changes in the contact angle of water droplets and in cuticular transpiration were also measured. By using material from a polluted and an unpolluted site it was shown that the ageing process occurs faster on polluted air, leading to greater cuticular transpiration and smaller contact angles at polluted sites.

  • Cape, ORCID ID:E-mail:
  • Fowler, ORCID ID:E-mail:
article id 5144, category Article
Lennart Folkeson. (1981). Impact of air-borne copper and zinc pollution on lichen and bryophyte vegetation near a brass foundry. Silva Fennica vol. 15 no. 4 article id 5144. https://doi.org/10.14214/sf.a15371

Air-borne Cu and Zn from a brass foundry at Gusum, SE Sweden, have considerably disturbed the lichen and bryophyte vegetation in the coniferous forest environment. The occurrence of lichens on Norway spruce twigs decreased rapidly with increasing Cu concentrations in Hypogymnia physodes above 90 ppm (background value 10–15). The epiphytic vegetation is reduced within 2–3 km from the foundry. Only stunted individuals occur in the close vicinity of the pollution source.

The cover of one of the quantitatively most important mosses, Hylocomnium splendens, is greatly reduced by the heavy-metal deposition. Cover values of 20–50% are not uncommon in distant sites (Cu concentration 15–35 ppm). There is a significant negative correlation between Cu concentration in the moss and its cover. The moss cannot survive much more than ca. 130 ppm Cu (and 360 ppm Zn). Live individuals are no more found within 1.5 km from the foundry.

  • Folkeson, ORCID ID:E-mail:
article id 5141, category Article
Lisbeth Mortensen, Knud V. Weisberg. (1981). A method for measurement of actue leaf injury on tobacco indicator plants. Silva Fennica vol. 15 no. 4 article id 5141. https://doi.org/10.14214/sf.a15368

A technique for instrumental scoring of damaged leaves on tobacco (Nicotiana tabacum) indicator plants caused by ozone in the lower atmosphere is being developed. The leaves are photographed in situ with an integrated unit, which illuminates the leaf from behind and keeps the camera in a well-defined position. By using microfilm and a minus green filter, it is possible to obtain negatives where the necrotic flecks appear as dark spots on a white leaf. The negatives are scanned in a TV-system and the size of the damaged fraction of the leaf is calculated by a microprosessor and is shown as a percentage of the leaf.

  • Mortensen, ORCID ID:E-mail:
  • Weisberg, ORCID ID:E-mail:
article id 5141, category Article
Lisbeth Mortensen, Knud V. Weisberg. (1981). A method for measurement of actue leaf injury on tobacco indicator plants. Silva Fennica vol. 15 no. 4 article id 5141. https://doi.org/10.14214/sf.a15368

A technique for instrumental scoring of damaged leaves on tobacco (Nicotiana tabacum) indicator plants caused by ozone in the lower atmosphere is being developed. The leaves are photographed in situ with an integrated unit, which illuminates the leaf from behind and keeps the camera in a well-defined position. By using microfilm and a minus green filter, it is possible to obtain negatives where the necrotic flecks appear as dark spots on a white leaf. The negatives are scanned in a TV-system and the size of the damaged fraction of the leaf is calculated by a microprosessor and is shown as a percentage of the leaf.

  • Mortensen, ORCID ID:E-mail:
  • Weisberg, ORCID ID:E-mail:
article id 5123, category Article
Heljä-Sisko Katainen, Seppo Kellomäki. (1981). Happaman veden vaikutus männyn taimiin. Silva Fennica vol. 15 no. 3 article id 5123. https://doi.org/10.14214/sf.a15064
English title: Effect of foliar application of dilute sulphuric acid on Scots pine seedlings.

Needle damages, transpiration, photosynthesis and needle and stem height growth of Scots pine (Pinus sylvestris L.) seedlings treated with dilute sulphuric acid were studied. The acidity of the solution was pH 3. Application of a dilute solution of sulphuric acid equivalent to the normal amount of precipitation occurring during the growing season damaged the surface of two-year-old needles but not that of the current-year needles. A reduction in the photosynthetic rate of 10–30% was observed compared with the untreated seedlings. Transpiration of the seedlings was not affected by the treatment. Needle growth and stem height growth of the seedlings growing on a substrate representing poor sandy soil were reduced. Increased needle growth and stem height growth were characteristic for the seedlings growing on substrate representing fertile moraine.

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  • Katainen, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
article id 5110, category Article
Helena Lehtiö. (1981). Effect of air pollution on the volatile oil in needles of Scots pine (Pinus sylvestris L.). Silva Fennica vol. 15 no. 2 article id 5110. https://doi.org/10.14214/sf.a15051

The amount of volatile oil and monoterpene composition in Scots pine (Pinus sylvestris L.) needles were studied in trees growing near two factories and in the city of Kuopio, Central Finland. Trees in these locations are exposed principally to sulphur dioxide and fluoride emissions.

The amount of volatile oil increased with increasing injury class in the trees growing near the fertilizer factory. The amounts of volatile oil in trees near the pulp mill differed in the various injury classes. More oil was found in younger needles. The greatest differences in monoterpene composition were in the amounts of camphene, α-pinene, myrcene and tricyclene.

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  • Lehtiö, ORCID ID:E-mail:
article id 5088, category Article
Reijo Solantie, Kari Ahti. (1980). Säätekijöiden vaikutus Etelä-Suomen lumituhoihin v. 1959. Silva Fennica vol. 14 no. 4 article id 5088. https://doi.org/10.14214/sf.a15029
English title: The influence of weather on the snow damages for forests in Southern Finland in 1959.

Snow and rime, attached to branches of conifers, seriously damaged forests in a region of 11,000 km2 in Southern Finland during a passage of two nearly occluded cyclones in 1959. The roles of different weather elements were studied by considering the variations occurring in them over this region and its surroundings. Damage occurred only inside an accentuated pattern of copious orographic precipitation. Precipitation only became attached to and retained on branches in such parts of the area where temperature varied on both sides of freezing point but did not exceed 0.6°C. Furthermore, damage only occurred in forests where rime formed (above a certain level and on sloping towards the prevailing wind).

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  • Solantie, ORCID ID:E-mail:
  • Ahti, ORCID ID:E-mail:
article id 5082, category Article
K. M. Bhat. (1980). Pith flecks and ray abnormalities in birch wood. Silva Fennica vol. 14 no. 3 article id 5082. https://doi.org/10.14214/sf.a15023

Samples that had extensive pith flecks, caused by the larvae of Dendromyza betulae (now Phytobia betulae E.Kang), were collected from two trees of Betula pendula Roth and two B. pubescens Erhr. The age of the trees varied from 45 to 56 years. The effect of larvae injury on the rays was studied. The width of affected rays in both species was more than twice that of normal rays. The height and frequency also increased considerably. When describing the anatomy of Betula species the pith flecks should be treated with caution in order to avoid confusion and misinterpretation. 

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  • Bhat, ORCID ID:E-mail:
article id 5074, category Article
Jukka Selander, Matti Nuorteva. (1980). Feromonivalmisteen käyttö kirjanpainajien torjumiseksi kuolevassa kuusikossa. Silva Fennica vol. 14 no. 2 article id 5074. https://doi.org/10.14214/sf.a15015
English title: Use of synthetic pheromones for the control of spruce bark beetle in a heavily infested Norway spruce stand.

The dying-off of more trees in an over-aged Norway spruce (Picea abies (L.) H. Karst.) stand caused by Ips-bark beetles was reduced by a pheromone preparation, ipslure. 20 preparations placed in trapping bolts captured more than 13,700 specimens of Ips typographus L. and Ips duplicatus Sahlb., which alone corresponded to a saving of five old trees in this valuable exhibition and seed collection stand. Attractance of ipslure to the following predators of bark beetles was also examined; Thanasimus formicarius, T. rufipes, Epuracea bickhardti, Rhizophagus ferrugineus, Pityophagus ferrugineus.

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  • Selander, ORCID ID:E-mail:
  • Nuorteva, ORCID ID:E-mail:
article id 5022, category Article
Jukka Selander, Paavo Kalo. (1979). Männyn taimen pihkan monoterpeenien vaikutuksista tuhonkestävyyteen tukkimiehentäitä, Hylobius abietis L. ( Coleoptera, Curculionidae) vastaan. Silva Fennica vol. 13 no. 2 article id 5022. https://doi.org/10.14214/sf.a14876
English title: Evaluation of resistance of Scots pine seedlings against the large pine weevil Hylobius abietis L. in relation to their monoterpene composition.

The development of Scots pine (Pinus sylvestris L.) seedlings and damage caused by Hylobius abietis L. (Coleoptera, Curculionidae) were studied during a three-year period. Olfactory responses of H. abietis was studied in laboratory with several volatile oils isolated from different kinds of P. sylvestris seedlings. Resistance of seedlings against H. Abietis was evaluated in terms of their monoterpene composition. Three aspects of resistance (preference, antibiosis and tolerance) were evaluated separately. Seedling chemotype was found to be associated with these aspects of host resistance on only minor scale. Discussion was attached to a further search for host resistance arising from other properties and constituents of oleoresin. Height growth of the seedlings recovering from weevil damage was 86–91% compared to healthy seedlings.

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  • Selander, ORCID ID:E-mail:
  • Kalo, 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 4992, category Article
Kari Löyttyniemi, Raimo Hiltunen. (1978). Monoterpenes in Scots pine in relation to browsing preference by moose (Alces alces L.). Silva Fennica vol. 12 no. 2 article id 4992. https://doi.org/10.14214/sf.a14846

Monoterpene hydrocarbon contents of needles in Scots pine (Pinus sylvestris L.) plants both damaged and untouched by the moose (Alces alces L.) were compared in the study. The material was collected in an 8-year-old plantation in Central Finland. Needle samples were taken from the topmost shoot whorl of the plants in the middle of April, 1976. Only minor differences were found between the plant groups. Thus, terpenes in pine presumably play no important role in the browsing preference by moose.

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  • Löyttyniemi, ORCID ID:E-mail:
  • Hiltunen, ORCID ID:E-mail:
article id 7088, category Article
Uunio Saalas. (1919). Kaarnakuoriaisista ja niiden aiheuttamista vahingoista Suomen metsissä. Acta Forestalia Fennica vol. 10 no. 1 article id 7088. https://doi.org/10.14214/aff.7088
English title: Bark beetles and insect damages in Finnish forest.

The aim of the study was to investigate the abundance of bark beetle species and their damage in Finland. The bark beetle populations were studied in several areas in Finland, both in sites with known beetle damage and without. Two-meter wide lines were measured in the sample plots, where all trees were studied for bark beetle damage in the stem and the crown of the trees. The abundance of bark beetle species and the beetle damages in 25 study areas, and 52 different species are discussed in detail.

Divided by their lifestyle, the most important groups of bark beetles are the pine shoot beetles (Tomicus sp.), beetles reproducing in Scots pine (Pinus sylvestris L.) stems and branches under the bark, beetles reproducing in Norway spruce (Picea abies (L.) H. Karst.) stems and branches under the bark, beetles living in the other coniferous trees, beetles reproducing in roots, beetles reproducing under the Betula sp. bark, beetles reproducing in other deciduous trees and beetles reproducing inside of the stems. Of individual species, Blastophagus piniperda (now Tomicus piniperda) and B. minor cause worst damage to pine and Ips typographus (L.) and Pityogenes chalcographus (L.) to spruce. Serious damage is caused also by Xyloterus lineatus to coniferous trees, Polygraphus polygraphus and P. subopacus to Norway spruce and Scolytus Ratzburgi to Betula sp.

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  • Saalas, ORCID ID:E-mail:
article id 7017, category Article
A. J. Bonsdorff. (1918). Beiträge zur Kenntnis der Sturmschäden in Finnland. Acta Forestalia Fennica vol. 8 no. 2 article id 7017. https://doi.org/10.14214/aff.7017
English title: Writings on knowledge on wind damages in Finland.

The article represents, based on meteorological data from 1900-1910 and 1911-1915 and annual reports of forest directorate with descriptions or statistics about wind damages of trees in state owned lands, the biggest storms in Finland and the damage they have caused to forests. The most powerful storms of the studied period and damages they caused are presented.  

It was found out that the storm damages take place primarily during the growing season. Frozen ground and a snow cover protects the trees from falling.
  • Bonsdorff, ORCID ID:E-mail:
article id 7017, category Article
A. J. Bonsdorff. (1918). Beiträge zur Kenntnis der Sturmschäden in Finnland. Acta Forestalia Fennica vol. 8 no. 2 article id 7017. https://doi.org/10.14214/aff.7017
English title: Writings on knowledge on wind damages in Finland.

The article represents, based on meteorological data from 1900-1910 and 1911-1915 and annual reports of forest directorate with descriptions or statistics about wind damages of trees in state owned lands, the biggest storms in Finland and the damage they have caused to forests. The most powerful storms of the studied period and damages they caused are presented.  

It was found out that the storm damages take place primarily during the growing season. Frozen ground and a snow cover protects the trees from falling.
  • Bonsdorff, ORCID ID:E-mail:
article id 7016, category Article
A. J. Bonsdorff. (1917). Studien über die Sturmrichtungen in Finnland. Acta Forestalia Fennica vol. 8 no. 1 article id 7016. https://doi.org/10.14214/aff.7016
English title: Studies on directions of the storms in Finland.

There are lot of storm damages in the Finnish forests. They are particularly common in forests logged as strips or with clear cuts, but not absent in selection forestry either. To protect the forests from natural disasters requires more intensive management. For the forestry purposes it is important to know the most common wind directions of different parts of the country. The paper finds out which stormy wind directions are most dangerous to Finnish forests and hence need to be mostly taken into consideration when planning logging operations.  The study is based on meteorological data that has been compared with the reports of storm damages in state owned forests.

The most storm damage take place during the growing season, and to some extent in late fall. The regeneration felling should take place against the primary direction of the stormy winds. The paper represents the most common wind directions for different parts of the country. However, the wind directions may vary from the primary with local conditions such as altitude differences. 

  • Bonsdorff, ORCID ID:E-mail:
article id 7016, category Article
A. J. Bonsdorff. (1917). Studien über die Sturmrichtungen in Finnland. Acta Forestalia Fennica vol. 8 no. 1 article id 7016. https://doi.org/10.14214/aff.7016
English title: Studies on directions of the storms in Finland.

There are lot of storm damages in the Finnish forests. They are particularly common in forests logged as strips or with clear cuts, but not absent in selection forestry either. To protect the forests from natural disasters requires more intensive management. For the forestry purposes it is important to know the most common wind directions of different parts of the country. The paper finds out which stormy wind directions are most dangerous to Finnish forests and hence need to be mostly taken into consideration when planning logging operations.  The study is based on meteorological data that has been compared with the reports of storm damages in state owned forests.

The most storm damage take place during the growing season, and to some extent in late fall. The regeneration felling should take place against the primary direction of the stormy winds. The paper represents the most common wind directions for different parts of the country. However, the wind directions may vary from the primary with local conditions such as altitude differences. 

  • Bonsdorff, ORCID ID:E-mail:
article id 4871, category Article
Kari Löyttyniemi. (1972). Hybridihaavikoiden hyönteistuhoista. Silva Fennica vol. 6 no. 3 article id 4871. https://doi.org/10.14214/sf.a14678
English title: Insect damages in hybrid aspen stands.
Original keywords: hybridihaapa; hyönteistuhot

Hybrid aspen (Populus tremula L. x Populus tremuloides Michx.) has been grown in Finland for about 20 years, and the area of the stands is currently about 400 ha. Growing is planned to be greatly expanded to grow raw material for match industry. The aim of this investigation was to study susceptibility of hybrid aspen to insect damages. Insect damages in hybrid aspen, growing in Southern Finland, were examined in 15 stands in 1972. Saperda species were observed to be the most numerous and harmful insect species. Saperda carcharias L. occurred in 26% and Saperda populnea L. in 36% off trees inspected. Mass occurrence of Chionaspis salicis L. was observed in some sample areas.

  • Löyttyniemi, ORCID ID:E-mail:
article id 4870, category Article
Matti Nuorteva. (1972). Tumamonisärmiöviruksen käytöstä ruskean mäntypistiäisen (Neodiprion sertifer Geoffr.) torjunnassa. Silva Fennica vol. 6 no. 3 article id 4870. https://doi.org/10.14214/sf.a14676
English title: Use of the nuclear polyhedrosis virus in the control of the European pine sawfly (Neodiprion sertifer Geoff.).

Experimental applications of the nuclear polyhedrosis virus (Borrelinavirus diprionis) to control of the European pine sawfly (Neodiprion sertifer Geoff.) was carried out during the last outbreak of this sawfly in in Scots pine (Pinus sylvestris L.) in Finland in 1963. Quantities of polyhedrosis virus preparation, collected and purified in Finland were available as concentrations packed in capsules. Spraying took place in three localities in southwestern Finland when the larvae were in I–III instars.

When Finnish and Swedish preparations were used 83–96% of larval colonies were completely destroyed within 14 days. In addition, an attempt was made to change the virus in latent stage, present already in the area, to acute stage by application of substrates which are probably harmless to pine, but were expected to stress the larvae. Ground quarts as spray had the best lethal effect upon larvae.

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  • Nuorteva, 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 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 4778, category Article
Kari Löyttyniemi. (1968). Teeri (Lyrurus tetrix L.) männyn taimien tuholaisena taimitarhassa. Silva Fennica vol. 2 no. 4 article id 4778. https://doi.org/10.14214/sf.a14563
English title: Feeding of terminal shoots of Scots pine seedlings by the black grouse (Lyrurus tetrix) in nursery.
Original keywords: taimitarha; taimituhot; mänty; versot; teeri

In early spring 1968 it was noticed that the black grouses (Lyrurus tetris L.) was eating terminal shoots of Scots pine (Pinus sylvestris L.) seedlings in a tree nursery in Luumäki, Southern Finland. The terminal shoots were picked 1–4 cm from the top of the seedlings. In total some thousands of two-year-old seedlings were damaged. The depth of the snow was 10–15 cm deep and only the tops of the seedlings could be seen above the surface of the snow.

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  • Löyttyniemi, ORCID ID:E-mail:
article id 4746, category Article
Kari Löyttyniemi. (1967). Tikaskuoriaisesta (Trypodendron lineatum Oliv., Col., Scolytidae) kuorellisen havupuutavaran pilaajana. Silva Fennica vol. 1 no. 2 article id 4746. https://doi.org/10.14214/sf.a14456
English title: Damages caused to timber with bark by spruce ambrosia beetle (Trypodendron lineatum) in Finland.

The paper studied the effect of felling time and conditions in the forest depot of timber to damages caused by spruce ambrosia beetle (Trypodendron lineatum Oliv.) to coniferous timber with bark, both experimentally and observing forest depots in Finland. Effects of fellings was studied by studying the abundance of the beetles in logging residue.

The results show that the spruce ambrosia beetles favour timber felled during the late autumn and winter, stored in a shaded place in the forest. In addition, new spruce stumps maintain and increase the beetle population. Fellings in the forest will increase population during the next year and cause damages in forest depot of timber nearby, because the insect breeds in the stumps. The experiments showed that it is possible to diminish the damages caused by the beetle to timber with bark by spraying with insecticides, and timing the fellings and transport of timber so that there is no timber in the forest in the spring during the time when the insect swarms.

The PDF includes a summary in German.

  • Löyttyniemi, ORCID ID:E-mail:
article id 7670, category Article
Risto Heikkilä. (1991). Moose browsing in a Scots pine plantation mixed with deciduous tree species. Acta Forestalia Fennica no. 224 article id 7670. https://doi.org/10.14214/aff.7670

The utilization of available food resources by the moose (Alces alces L.) was studied in a Scots pine (Pinus sylvestris L.) plantation containing an admixture of deciduous species. Rowan (Sorbus aucuparia L.) and aspen (Populus tremula L.) were highly utilized compared to pine and both silver birch (Betula pendula Roth) and downy birch (B. pubescens Ehrh.). However, they were not capable of withstanding continuous browsing by moose owing to their diminished biomass. In total, the browsing intensity (number of browsed twigs/tree) on pine and birch was about double of that on rowan and aspen.

The number of browsed twigs per tree increased as the amount of available main branches increased. The number of bites per available branch, as well as the maximum diameter of the bites, decreased as the density of the plantation increased. Silver birch was more used by moose than pubescent birch as well as planted silver birch compared with naturally regenerated trees.

Main stem breakage was especially common in winter 1988, the average height of the pine and birch trees being over two meters. The tops of broken stems were commonly utilized as food. The increase in moose density and the relatively deep snow cover evidently promoted the incidence of serious damage. The number of undamaged trees/ha was greater in dense than in sparse parts of the stand.

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  • Heikkilä, ORCID ID:E-mail:
article id 7663, category Article
Anne Sairanen. (1990). Site characteristics of Scots pine stands infected by Gremmeniella abietina in Central Finland. 1: Mineral soil sites. Acta Forestalia Fennica no. 216 article id 7663. https://doi.org/10.14214/aff.7663

Mineral soil sites where Scots pine (Pinus sylvestris L.) were suffering from Gremmeniella abietina die-back (Lagerb.) M. Morelet. were characterized and classified in Central Finland. The tree stand, ground vegetation, soil type and site topography were described in 163 sample plots in 16 stands. The sites were classified according to system developed by Cajander and numerically using TWINSPAN analysis based on the ground vegetation. The site topography of severely damaged stands was checked from colour infrared aerial photographs. The disease was most severe in depressions and frost pockets. Apart from topography no significant correlations were found between disease severity and site factors. No typical vegetational pattern of forest type of the severely affected stands could be detected. Most of the stands were growing on medium-coarse, unfertile soil with a rather thick humus layer.

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  • Sairanen, ORCID ID:E-mail:
article id 7659, category Article
Ari Lääperi. (1990). Hoidettujen talvilaitumien vaikutus hirvituhoihin mäntytaimikoissa. Acta Forestalia Fennica no. 212 article id 7659. https://doi.org/10.14214/aff.7659
English title: Effect of winter feeding on moose damage to young Scots pine stands.

The establishment of moose (Alces alces L.) winter feeding sites, their utilization and their effect on damage to young Scots pine (Pinus sylvestris L.) plantations was studied in Ruokolahti-Imatra area in Eastern Finland in 1987–89. During the period, the density in the area was about 3–5 moose/ 1,000 ha.

Six feeding sites were established by fertilization, offering mineral lics and the tops of aspen and Scot pine and by salting the tops of pine. The moose preferred the feeding site to control areas during both summer and winter. In winter browsing was very heavy, especially in those areas located in or close to traditional wintering areas. In winter no moose were seen in the summer habitats.

The extent of, and fluctuations in moose damage were studied in 47 Scots pine plantations in the immediate surroundings of the feeding sites (29 plantations), control areas (18 plantations) and also 68 randomly selected pine plantations. Before the experiment began in 1987 four plantations had been seriously damaged. During the study period only one plantation was seriously damaged. However, it could not be conclusively proved that damage to the pine plantations had been reduced as a result of the feeding sites. The results of the study can be put into practice elsewhere to create better living conditions for moose in their winter habitats. However, the food offered at the feeding site should be in the right proportion to the number of animals wintering in the area, so that the risk of damage to nearby plantations would be kept as small as possible.

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  • Lääperi, ORCID ID:E-mail:
article id 7604, category Article
Jukka Laine, Hannu Mannerkoski. (1980). Lannoituksen vaikutus mäntytaimikoiden kasvuun ja hirvituhoihin karuilla ojitetuilla nevoilla. Acta Forestalia Fennica no. 166 article id 7604. https://doi.org/10.14214/aff.7604
English title: Effect on fertilization on tree growth and elk damage in young Scots pine stands planted on drained, nutrient-poor open bogs in Finland.

An attempt was made in this study to determine which nutrients and in what amounts should be used in the fertilization of Scots pine (Pinus sylvestris L.) seedling stands on nutrient-poor open bogs in order to obtain optimum seedling growth and to minimize the risk of elk damage.

The most important nutrient to improve seedling growth in the experiments was phosphorus. Already rather small amounts produced a significant effect although the effect of higher dosages seemed to be longer lasting. After fertilization also nitrogen gave significant increase in growth. The number of seedlings damaged by elk increased the most on N-fertilized plots. Also, phosphorus increased the occurrence of elk damage, but effect seemed to be related to the better growth and more suitable size of P-fertilized seedlings. The effect of potassium on seedling growth and on occurrence of elk damage was negligible.

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  • Laine, ORCID ID:E-mail:
  • Mannerkoski, ORCID ID:E-mail:
article id 7570, category Article
Antti Isomäki, Tauno Kallio. (1974). Consequences of injury caused by timber harvesting machines on the growth and decay of spruce (Picea abies (L.) Karst.). Acta Forestalia Fennica no. 136 article id 7570. https://doi.org/10.14214/aff.7570

The study material was collected from 10 localities in South Finland in 1971–72. The material comprised 816 damaged Norway spruce (Picea abies (L.) H. Karst.) trees with a total of 978 injuries.

Decay (discoloration) spread upward from the damaged point was about three times as fast as downward. The mean rate of advance upward was 21 cm/year. The decay spreading at the quickest rate started from above-ground root collar injuries. The size of the damaged area (surface area, width and depth) correlated positively with the rate of increase in decay initiated by the injury. For the first 10 years the decay advanced at the same rate after which the advance became slower though not ceasing. Damage produced in the early summer caused a faster spread of decay than that produced in the late summer or winter. The rate of advance was the greater the larger the stem involved. When decay started from trunk damage its rate of advance was greater the faster the growth of the trees. With a better soil type, the rate of advance in decay increased. Fertilization increased the rate of advance.

The widest stem injuries reduced tree growth by about one-third, and severed roots by nearly half of the growth of trees where the width of the injuries was 0–4 cm. Fomes annosus (Heterobasidion annosum) infected spruce injuries especially in the southern coastal district. The farthest tips of discoloration proved in most cases to be sterile. The most common fungus isolated from these sites was Stereum sanguinolentum.

The PDF includes a summary in Finnish.

  • Isomäki, ORCID ID:E-mail:
  • Kallio, ORCID ID:E-mail:
article id 7570, category Article
Antti Isomäki, Tauno Kallio. (1974). Consequences of injury caused by timber harvesting machines on the growth and decay of spruce (Picea abies (L.) Karst.). Acta Forestalia Fennica no. 136 article id 7570. https://doi.org/10.14214/aff.7570

The study material was collected from 10 localities in South Finland in 1971–72. The material comprised 816 damaged Norway spruce (Picea abies (L.) H. Karst.) trees with a total of 978 injuries.

Decay (discoloration) spread upward from the damaged point was about three times as fast as downward. The mean rate of advance upward was 21 cm/year. The decay spreading at the quickest rate started from above-ground root collar injuries. The size of the damaged area (surface area, width and depth) correlated positively with the rate of increase in decay initiated by the injury. For the first 10 years the decay advanced at the same rate after which the advance became slower though not ceasing. Damage produced in the early summer caused a faster spread of decay than that produced in the late summer or winter. The rate of advance was the greater the larger the stem involved. When decay started from trunk damage its rate of advance was greater the faster the growth of the trees. With a better soil type, the rate of advance in decay increased. Fertilization increased the rate of advance.

The widest stem injuries reduced tree growth by about one-third, and severed roots by nearly half of the growth of trees where the width of the injuries was 0–4 cm. Fomes annosus (Heterobasidion annosum) infected spruce injuries especially in the southern coastal district. The farthest tips of discoloration proved in most cases to be sterile. The most common fungus isolated from these sites was Stereum sanguinolentum.

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  • Isomäki, ORCID ID:E-mail:
  • Kallio, ORCID ID:E-mail:
article id 7555, category Article
Paavo Havas. (1971). Injury to pines in the vicinity of a chemical processing plant in Northern Finland. Acta Forestalia Fennica no. 121 article id 7555. https://doi.org/10.14214/aff.7555

The present investigation shows that injury to pines (Pinus silvestris L.) in the boreal coniferous zone (65 °N) occurs in winter conditions in the vicinity of a fertilizer processing plant, unless they are covered by snow. This kind of injury has multiple causes. Firstly, fertilizer dust discharged from the process operations may reduce the degree of xeromorphism of the needles, which further results in disorders of the water economy. Secondly, along with the wet fertilizer dust the needles absorb toxic substances, especially, fluorides and certain sulphur compounds. The amounts of fluorides, in particular, are large enough to bring about damage. The combined effect of these factors causes trees to die during winters with long periods of intense cold. It seems, therefore, that in the northern conditions pollution may have effects not observable in more southern regions.

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  • Havas, ORCID ID:E-mail:
article id 4703, category Article
E. A. Jamalainen. (1960). Havupuiden taimistojen talvituhosienivauriot ja niiden kemiallinen torjunta. Silva Fennica no. 108 article id 4703. https://doi.org/10.14214/sf.a9138
English title: Damage by low-temperature parasitic fungi on coniferous nurseries and its chemical control.

Since 1954 studies have been carried out by the Department of Plant Pathology of Agricultural Research Centre on occurrence of low-temperature parasitic fungi in nurseries in Finland. This paper reports analysis of the damage caused by the fungus to Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seedlings.

In Southern and southwestern Finland, scarcely any damage caused by low-temperature parasitic fungi to coniferous seedlings was found. On the other hand, in Central, Eastern and Northern Finland, considerable injuries were present in the seedlings. The extent of damage varies between different localities and in a same location from year to year. The extent of damage is mostly dependent on snow cover which is heaviest in Central and Northern Finland. Damages are largest in wooded areas and in places where snow accumulates abundantly and remains until late in the spring.

The principal cause of winter damage to spruce seedlings is Hepotricia nigra (Hartig) which causes black snow mould. Depending on the amount of infestation, the damage can be limited to scattered groups or consist of large areas of dead seedlings. The fungus is unable to infect the plants during warm months of the growing season. The most damaging parasitic fungus in Scots pine is Phacidium infestans (Karst.) causing snow blight. The infestation varies from reddish-brown patches of infected seedlings to large areas of infected plants. Also, Botrytis cinerea has been determined from one- and two-year plants of pine and spruce.

In trials of chemical control by PCNB (pentachloronitrobenzene) gave nearly complete control of low-temperature parasitic fungi in one-year spruce seedlings. In addition, a compound of zineb (Dithane Z-78) gave similar results. Chemical control of the fungi is now common in the nurseries.

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  • Jamalainen, ORCID ID:E-mail:
article id 4695, category Article
Hirvivahinkokomitea. (1960). Hirvivahinkokomitean mietintö. Silva Fennica no. 106 article id 4695. https://doi.org/10.14214/sf.a9134
English title: Report of committee on damage by moose.

The increase in moose (Alces alces) population of Finland in 2000th century has caused significant damages in agriculture and forestry. Amendment was made to the Game Law to compensate damage by moose to agricultural crops from state funds. It has been suggested already in 1936 that compensations should be paid for the damages caused to the forests as well. Finally, in 1956 the Government appointed a committee to study the quality and quantity of the damages caused by moose to the young stands. The committee carried out an inquiry about the extent of the damage in 1956–1957, in which 12,000 private forest holdings were studied.

According to the study, moose cause damage mainly to young Scots pine stands in Southwestern Finland and Western Finland, and the districts of Uusimaa-Häme, East Häme, South Karelia and East Savo. However, the number of forest holdings suffering from damage was relatively low, about 5.6% in the whole country in 1951–1956. The damage is concentrated on Scots pine-, aspen, and birch-dominated young stands. The study of the level of the damage showed, that only 14% of the pine and 17% of stands of other tree species should be reforested due to the damage.

The committee suggests that compensation is paid for those damages that require reforestation. Reforestation would be affected with the help of State relief funds under the provision of the Act on Forest Improvement. The owner would also receive a tax reduction for a lost growing season. In addition, attention to moose damages in the forests should be taken into account when moose hunting permissions are issued.

The PDF includes a summary in English.

  • Hirvivahinkokomitea, ORCID ID:E-mail:
article id 4695, category Article
Hirvivahinkokomitea. (1960). Hirvivahinkokomitean mietintö. Silva Fennica no. 106 article id 4695. https://doi.org/10.14214/sf.a9134
English title: Report of committee on damage by moose.

The increase in moose (Alces alces) population of Finland in 2000th century has caused significant damages in agriculture and forestry. Amendment was made to the Game Law to compensate damage by moose to agricultural crops from state funds. It has been suggested already in 1936 that compensations should be paid for the damages caused to the forests as well. Finally, in 1956 the Government appointed a committee to study the quality and quantity of the damages caused by moose to the young stands. The committee carried out an inquiry about the extent of the damage in 1956–1957, in which 12,000 private forest holdings were studied.

According to the study, moose cause damage mainly to young Scots pine stands in Southwestern Finland and Western Finland, and the districts of Uusimaa-Häme, East Häme, South Karelia and East Savo. However, the number of forest holdings suffering from damage was relatively low, about 5.6% in the whole country in 1951–1956. The damage is concentrated on Scots pine-, aspen, and birch-dominated young stands. The study of the level of the damage showed, that only 14% of the pine and 17% of stands of other tree species should be reforested due to the damage.

The committee suggests that compensation is paid for those damages that require reforestation. Reforestation would be affected with the help of State relief funds under the provision of the Act on Forest Improvement. The owner would also receive a tax reduction for a lost growing season. In addition, attention to moose damages in the forests should be taken into account when moose hunting permissions are issued.

The PDF includes a summary in English.

  • Hirvivahinkokomitea, ORCID ID:E-mail:
article id 4693, category Article
Martti Nenonen, Juhani Jukola. (1960). Tukkimiehen täin (Hylobius abietis L.) tuhoista mäntytaimistoissa ja niiden torjunnasta DDT :n avulla. Silva Fennica no. 104 article id 4693. https://doi.org/10.14214/sf.a9132
English title: Pine weevil (Hylobius abietis L.) injuries and their control by DDT in Scots pine seedling stands.

The aim of the study was to find out more about pine weevil (Hylobious abietis L.) injuries in Scots pine (Pinus sylvestris L.) seedling stands and their control by means of DDT. For this purpose, inventories were made of seedling stands established earlier. Control experiments were made on burnt areas by planting seedlings dipped in a DDT emulsion.

The results of the inventories show that injuries caused by pine weevils can, in certain circumstances, especially in seedling stands established by planting, cause the complete failure in artificial regeneration. The extent and quality of the injuries vary greatly according to planting method, treatment of the cutting area, age of the seedling stand, environmental factors, and weather conditions. The most extensive injuries occur in regeneration areas of old Norway spruce stands burnt after clear cutting and planted with Scots pine seedlings. Injuries are greater in seedling stands established by planting, especially after broadcast burning, than in seedling stands originating either from artificial or natural seeding. The quality of the patch for sowing or planting has a considerable effect on the quantity and character of the injuries: in a patch from which organic matter has been removed, injuries do not appear or they are slighter. Seedlings can be protected effectively and economically by dipping their tops up to the root collar, in a DDT emulsion before planting.

The PDF includes a summary in English.

  • Nenonen, ORCID ID:E-mail:
  • Jukola, ORCID ID:E-mail:
article id 4693, category Article
Martti Nenonen, Juhani Jukola. (1960). Tukkimiehen täin (Hylobius abietis L.) tuhoista mäntytaimistoissa ja niiden torjunnasta DDT :n avulla. Silva Fennica no. 104 article id 4693. https://doi.org/10.14214/sf.a9132
English title: Pine weevil (Hylobius abietis L.) injuries and their control by DDT in Scots pine seedling stands.

The aim of the study was to find out more about pine weevil (Hylobious abietis L.) injuries in Scots pine (Pinus sylvestris L.) seedling stands and their control by means of DDT. For this purpose, inventories were made of seedling stands established earlier. Control experiments were made on burnt areas by planting seedlings dipped in a DDT emulsion.

The results of the inventories show that injuries caused by pine weevils can, in certain circumstances, especially in seedling stands established by planting, cause the complete failure in artificial regeneration. The extent and quality of the injuries vary greatly according to planting method, treatment of the cutting area, age of the seedling stand, environmental factors, and weather conditions. The most extensive injuries occur in regeneration areas of old Norway spruce stands burnt after clear cutting and planted with Scots pine seedlings. Injuries are greater in seedling stands established by planting, especially after broadcast burning, than in seedling stands originating either from artificial or natural seeding. The quality of the patch for sowing or planting has a considerable effect on the quantity and character of the injuries: in a patch from which organic matter has been removed, injuries do not appear or they are slighter. Seedlings can be protected effectively and economically by dipping their tops up to the root collar, in a DDT emulsion before planting.

The PDF includes a summary in English.

  • Nenonen, ORCID ID:E-mail:
  • Jukola, ORCID ID:E-mail:
article id 7609, category Article
Matti Kärkkäinen. (1969). Metsän vaurioituminen kesäaikaisessa puunkorjuussa. Acta Forestalia Fennica no. 100 article id 7609. https://doi.org/10.14214/aff.7609
English title: The amount of injuries caused by timber transportation in the summer.

The purpose of this study was to build a mathematic predictive model for the formation of injuries and to try its usability in predicting. The empirical data consisted of 24 thinning sites, which were situated mainly in forests owned by forestry companies. The timber was made by strip roads. The terrain transportation of timber was carried out by forwarders or by agricultural tractor-trailer combinations.

The model has been compiled by multiple regression analysis. The predictive model has been interpreted so that the formation of injuries is, for one part, dependent of the number of trees exposed to damages, and, on the other hand, on the factors influencing the probability of injuries, the possibility for this existing. The number of trees exposed to injuries is dependent on the density of strip roads and on the amount of standing timber left after logging. The probability of injuries is influenced by the quality of the standing timber, the type of soil and the intensity of the timber harvesting process.

The predictive model has been interpreted in similar way as the number of injured trees. The possibility of formation of injuries is mainly affected by the length of strip roads and the amount of the standing timber. The probability of injuries is influenced, for the part of the number of root injuries by the strength of the soil type, and probably also by transportation equipment. For the amount of stem injuries no valid predictive equation was found in this study.

  • Kärkkäinen, ORCID ID:E-mail:
article id 7609, category Article
Matti Kärkkäinen. (1969). Metsän vaurioituminen kesäaikaisessa puunkorjuussa. Acta Forestalia Fennica no. 100 article id 7609. https://doi.org/10.14214/aff.7609
English title: The amount of injuries caused by timber transportation in the summer.

The purpose of this study was to build a mathematic predictive model for the formation of injuries and to try its usability in predicting. The empirical data consisted of 24 thinning sites, which were situated mainly in forests owned by forestry companies. The timber was made by strip roads. The terrain transportation of timber was carried out by forwarders or by agricultural tractor-trailer combinations.

The model has been compiled by multiple regression analysis. The predictive model has been interpreted so that the formation of injuries is, for one part, dependent of the number of trees exposed to damages, and, on the other hand, on the factors influencing the probability of injuries, the possibility for this existing. The number of trees exposed to injuries is dependent on the density of strip roads and on the amount of standing timber left after logging. The probability of injuries is influenced by the quality of the standing timber, the type of soil and the intensity of the timber harvesting process.

The predictive model has been interpreted in similar way as the number of injured trees. The possibility of formation of injuries is mainly affected by the length of strip roads and the amount of the standing timber. The probability of injuries is influenced, for the part of the number of root injuries by the strength of the soil type, and probably also by transportation equipment. For the amount of stem injuries no valid predictive equation was found in this study.

  • Kärkkäinen, ORCID ID:E-mail:
article id 7609, category Article
Matti Kärkkäinen. (1969). Metsän vaurioituminen kesäaikaisessa puunkorjuussa. Acta Forestalia Fennica no. 100 article id 7609. https://doi.org/10.14214/aff.7609
English title: The amount of injuries caused by timber transportation in the summer.

The purpose of this study was to build a mathematic predictive model for the formation of injuries and to try its usability in predicting. The empirical data consisted of 24 thinning sites, which were situated mainly in forests owned by forestry companies. The timber was made by strip roads. The terrain transportation of timber was carried out by forwarders or by agricultural tractor-trailer combinations.

The model has been compiled by multiple regression analysis. The predictive model has been interpreted so that the formation of injuries is, for one part, dependent of the number of trees exposed to damages, and, on the other hand, on the factors influencing the probability of injuries, the possibility for this existing. The number of trees exposed to injuries is dependent on the density of strip roads and on the amount of standing timber left after logging. The probability of injuries is influenced by the quality of the standing timber, the type of soil and the intensity of the timber harvesting process.

The predictive model has been interpreted in similar way as the number of injured trees. The possibility of formation of injuries is mainly affected by the length of strip roads and the amount of the standing timber. The probability of injuries is influenced, for the part of the number of root injuries by the strength of the soil type, and probably also by transportation equipment. For the amount of stem injuries no valid predictive equation was found in this study.

  • Kärkkäinen, ORCID ID:E-mail:
article id 4727, category Article
Erkki Pulliainen, Kalervo Salonen. (1965). Orava männyn siemen- ja silmutuholaisena. Silva Fennica no. 117 article id 4727. https://doi.org/10.14214/sf.a14285
English title: Damage caused by squirrel (Sciurus vulgaris) to pine-buds.
Original keywords: taimituhot; orava; silmut; kasvutappiot; mänty

When the seed harvest of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) are low, pine and spruce buds are among the secondary food items of squirrel (Sciurus vulgaris L.) in Finland. In this study, conducted in Nokia in Southern Finland in 1962-1963, eating of pine buds by squirrel is described. The eaten buds in 15-years old Scots pine seedlings were recorded in two seedling stands.

According to the results, the squirrels selected the largest buds of the best seedlings in the studied stands. In over 50% of the cases the squirrels chose only the buds of the leading shoot, especially the terminal bud. In half of the trees, a side bud of the leading shoot continued the growth, which causes form defects in the trees. In 35% of the damaged trees, a lateral branch continued the growth. Well-growing seedling stands may be especially susceptible for damages caused by, for instance, squirrels.

The PDF includes a summary in Finnish.

  • Pulliainen, ORCID ID:E-mail:
  • Salonen, ORCID ID:E-mail:
article id 4707, category Article
Oiva Suominen. (1961). Metsiköiden alttius lumituhoon. Tutkimus Etelä-Suomessa talvella 1958-59 sattuneesta lumituhosta. Silva Fennica no. 112 article id 4707. https://doi.org/10.14214/sf.a14234
English title: Susceptibility of stands to devastation by snow. Investigation into snow devastation in Southern Finland in winter 1958-59.
Original keywords: lumituhot; mesätuhot; etelärannikko

Exceptionally widespread snow damages occurred in January 1959 in the southern coastal region of Finland. An inquiry showed that significant devastation had occurred over an area of 42,620 ha. The purpose of the present investigation was to study the susceptibility to snow damages of different stands in different locations. Only the stem breakage was recorded. 924 stands along 92 one-kilometre lines were studied in the western continuation of Salpausselkä ridge in the summer 1960. A supplementary study was carried out in 1961 in separate stands.

Most heavily damaged stands were found in a damage zone closest (31–40 km) to the coast of Gulf of Finland. The damages were 39% fewer in the zone 61–70 km from the coast. No stands over 140 m above sea level escaped damage. Stands on the edge of an open area such as a field, lake etc. fared better than areas within the forest. Eastern slopes were more susceptible for snow damages in these weather conditions. Also, conifers were more frequently damaged than deciduous trees. Dense stands, and stands aged 61–100 years had most damages.

The PDF includes a summary in English.

  • Suominen, ORCID ID:E-mail:
article id 4707, category Article
Oiva Suominen. (1961). Metsiköiden alttius lumituhoon. Tutkimus Etelä-Suomessa talvella 1958-59 sattuneesta lumituhosta. Silva Fennica no. 112 article id 4707. https://doi.org/10.14214/sf.a14234
English title: Susceptibility of stands to devastation by snow. Investigation into snow devastation in Southern Finland in winter 1958-59.
Original keywords: lumituhot; mesätuhot; etelärannikko

Exceptionally widespread snow damages occurred in January 1959 in the southern coastal region of Finland. An inquiry showed that significant devastation had occurred over an area of 42,620 ha. The purpose of the present investigation was to study the susceptibility to snow damages of different stands in different locations. Only the stem breakage was recorded. 924 stands along 92 one-kilometre lines were studied in the western continuation of Salpausselkä ridge in the summer 1960. A supplementary study was carried out in 1961 in separate stands.

Most heavily damaged stands were found in a damage zone closest (31–40 km) to the coast of Gulf of Finland. The damages were 39% fewer in the zone 61–70 km from the coast. No stands over 140 m above sea level escaped damage. Stands on the edge of an open area such as a field, lake etc. fared better than areas within the forest. Eastern slopes were more susceptible for snow damages in these weather conditions. Also, conifers were more frequently damaged than deciduous trees. Dense stands, and stands aged 61–100 years had most damages.

The PDF includes a summary in English.

  • Suominen, ORCID ID:E-mail:
article id 4648, category Article
Paavo Yli-Vakkuri. (1955). Männyn kylvötaimistojen hirvivahingoista Pohjanmaalla. Silva Fennica no. 88 article id 4648. https://doi.org/10.14214/sf.a9111
English title: Elk damage in seedling stands of Scots pine in Ostrobothnia.

The article reviews the occurrence of damage causes by elk (Alces alces L.) in young Scots pine (Pinus sylvestris L.) stands established by direct seeding in the Ostrobothia region in Finland. The data was collected by random sampling, and consists of 110 sample plots in pine stands, established in 1930-1944.

Signs of elk damages could be observed in 20% of the stands. In more than half of the damaged stands pine seedlings were damaged by elk, on the rest of the stands the damage was targeted to hardwood saplings only. With the present density of elk population, the damage has an insignificant bearing upon the development of pine seedling stands in Ostrobothnia. The weaknesses of silvicultural state of the stands have been caused by other factors than elk.

Silviculturally weak stands were more liable to elk damage than strong ones. The occurrence of elk damage was more usual in stands with hardwood mixture than in pure pine stands. Especially goat willow, mountain ash and aspen, but also to some decree birch, seem to attract elk. Those factors that promote hardwood growth: fertility of the site, swampiness and the presence of seeding hardwoods in the area, increase the stand’s liability to elk damage.

The article includes an abstract in English and a summary in Swedish.

  • Yli-Vakkuri, ORCID ID:E-mail:
article id 4648, category Article
Paavo Yli-Vakkuri. (1955). Männyn kylvötaimistojen hirvivahingoista Pohjanmaalla. Silva Fennica no. 88 article id 4648. https://doi.org/10.14214/sf.a9111
English title: Elk damage in seedling stands of Scots pine in Ostrobothnia.

The article reviews the occurrence of damage causes by elk (Alces alces L.) in young Scots pine (Pinus sylvestris L.) stands established by direct seeding in the Ostrobothia region in Finland. The data was collected by random sampling, and consists of 110 sample plots in pine stands, established in 1930-1944.

Signs of elk damages could be observed in 20% of the stands. In more than half of the damaged stands pine seedlings were damaged by elk, on the rest of the stands the damage was targeted to hardwood saplings only. With the present density of elk population, the damage has an insignificant bearing upon the development of pine seedling stands in Ostrobothnia. The weaknesses of silvicultural state of the stands have been caused by other factors than elk.

Silviculturally weak stands were more liable to elk damage than strong ones. The occurrence of elk damage was more usual in stands with hardwood mixture than in pure pine stands. Especially goat willow, mountain ash and aspen, but also to some decree birch, seem to attract elk. Those factors that promote hardwood growth: fertility of the site, swampiness and the presence of seeding hardwoods in the area, increase the stand’s liability to elk damage.

The article includes an abstract in English and a summary in Swedish.

  • Yli-Vakkuri, ORCID ID:E-mail:
article id 4647, category Article
Pekka Sainio. (1955). Hirven talvisesta ravinnosta. Silva Fennica no. 88 article id 4647. https://doi.org/10.14214/sf.a9109
English title: Winter nutrition of elk.

Increase in the elk (Alces alces L.) population and the problems of its grazing has called for detailed research. The present study concentrated on three observation areas representing northern, western and eastern parts of Finland. There were 28 field observers watching 68 elks.

Earlier investigations in Finland indicate that aspen (Populus tremula L.) is the staple diet of elk. This study reached different conclusions, probably largely because of aspen is gradually becoming an increasingly rare tree species in Finland. According to this study, the principal food of elk in the winter is willow (Salix sp.). In the whole country, willow accounts for about 70% of elk’s nutrition. In the Far North the percentage is approx. 90. Of the other tree species, the order of preference is: aspen, Scots pine, mountain ash, juniper and birch. In addition, in Western Finland where snow is less deep, lingonberry and blueberry shrubs are on the menu. Beard moss on the spruce was frequently eaten locally. Elk seems to have eaten mainly the last annual shoot of trees and bushes. In few cases it has gnawed the bark of Scots pine, aspen and willow. Elk consumes in average 340 twigs or terminal shoots per day in the winter. This corresponds to about 1.8 kg of food.

The problem of elks damaging Scots pine seedlings has been observed in Western Finland, were the elk population is higher. The article suggests that suitable feeding places would be left for elk in places that are unsuitable for agriculture or forestry. Leaving, for instance, birch seedlings in Scots pine stands has been noticed to attract elks and to increase the damage to pine.

The article includes an abstract in English and a summary in Swedish.

  • Sainio, ORCID ID:E-mail:
article id 4647, category Article
Pekka Sainio. (1955). Hirven talvisesta ravinnosta. Silva Fennica no. 88 article id 4647. https://doi.org/10.14214/sf.a9109
English title: Winter nutrition of elk.

Increase in the elk (Alces alces L.) population and the problems of its grazing has called for detailed research. The present study concentrated on three observation areas representing northern, western and eastern parts of Finland. There were 28 field observers watching 68 elks.

Earlier investigations in Finland indicate that aspen (Populus tremula L.) is the staple diet of elk. This study reached different conclusions, probably largely because of aspen is gradually becoming an increasingly rare tree species in Finland. According to this study, the principal food of elk in the winter is willow (Salix sp.). In the whole country, willow accounts for about 70% of elk’s nutrition. In the Far North the percentage is approx. 90. Of the other tree species, the order of preference is: aspen, Scots pine, mountain ash, juniper and birch. In addition, in Western Finland where snow is less deep, lingonberry and blueberry shrubs are on the menu. Beard moss on the spruce was frequently eaten locally. Elk seems to have eaten mainly the last annual shoot of trees and bushes. In few cases it has gnawed the bark of Scots pine, aspen and willow. Elk consumes in average 340 twigs or terminal shoots per day in the winter. This corresponds to about 1.8 kg of food.

The problem of elks damaging Scots pine seedlings has been observed in Western Finland, were the elk population is higher. The article suggests that suitable feeding places would be left for elk in places that are unsuitable for agriculture or forestry. Leaving, for instance, birch seedlings in Scots pine stands has been noticed to attract elks and to increase the damage to pine.

The article includes an abstract in English and a summary in Swedish.

  • Sainio, ORCID ID:E-mail:
article id 4647, category Article
Pekka Sainio. (1955). Hirven talvisesta ravinnosta. Silva Fennica no. 88 article id 4647. https://doi.org/10.14214/sf.a9109
English title: Winter nutrition of elk.

Increase in the elk (Alces alces L.) population and the problems of its grazing has called for detailed research. The present study concentrated on three observation areas representing northern, western and eastern parts of Finland. There were 28 field observers watching 68 elks.

Earlier investigations in Finland indicate that aspen (Populus tremula L.) is the staple diet of elk. This study reached different conclusions, probably largely because of aspen is gradually becoming an increasingly rare tree species in Finland. According to this study, the principal food of elk in the winter is willow (Salix sp.). In the whole country, willow accounts for about 70% of elk’s nutrition. In the Far North the percentage is approx. 90. Of the other tree species, the order of preference is: aspen, Scots pine, mountain ash, juniper and birch. In addition, in Western Finland where snow is less deep, lingonberry and blueberry shrubs are on the menu. Beard moss on the spruce was frequently eaten locally. Elk seems to have eaten mainly the last annual shoot of trees and bushes. In few cases it has gnawed the bark of Scots pine, aspen and willow. Elk consumes in average 340 twigs or terminal shoots per day in the winter. This corresponds to about 1.8 kg of food.

The problem of elks damaging Scots pine seedlings has been observed in Western Finland, were the elk population is higher. The article suggests that suitable feeding places would be left for elk in places that are unsuitable for agriculture or forestry. Leaving, for instance, birch seedlings in Scots pine stands has been noticed to attract elks and to increase the damage to pine.

The article includes an abstract in English and a summary in Swedish.

  • Sainio, ORCID ID:E-mail:
article id 4546, category Article
Peitsa Mikola. (1938). Kuusen latvus- ja runkomuodosta Maanselän lumituhoalueella. Silva Fennica no. 47 article id 4546. https://doi.org/10.14214/sf.a9071
English title: Crown and stem form of Norway spruce in the snow damage areas of Maanselkä in Northern Finland.

Finnish tree species have adapted differently to heavy snow loads that occur especially in fell areas in Kuusamo and Salla as well as Maanselkä area in Sotkamo and Rautavaara in Northern Finland. Norway spruce (Picea abies Karst. L) is adapted better than Scots pine (Pinus sylvestris L.). The aim of this study was to investigate how crown and stem form of Norway spruce in the snow damage area of Maanselkä area differ from other areas in the same region.  

Relatively broad crown at the base of the stem, quickly tapering crown and narrow and even upper crown were typical for trees growing in the snow damaged areas. The higher the altitude is, the stronger tapering the crown is. The tapering begins usually in a height of 4-5 meters. Even the stem diameter begins to taper strongly at this height. In the areas where heavy snow does not cause snow damage, top of crown is broader. Also, in the snow damage areas the damaged trees seem to have broader crown shape than the trees with little damages.  

Height of the trees decreases in the snow damage areas compared to forests in lower altitudes, which can be caused both by wind and snow load. 

The article includes a German summary. 

  • Mikola, ORCID ID:E-mail:
article id 4464, category Article
Esko Kangas. (1932). Tutkimuksia kaasutuhoista Imatran valtionpuistossa. Silva Fennica no. 23 article id 4464. https://doi.org/10.14214/sf.a9020
English title: Studies on gas damages in the state forests in Imatra.

A forest damage was detected in spring 1931 near electro-chemical factory in Imatra in Eastern Finland. It was deduced that it was caused by a gas discharge from the factory. A survey was made to describe the damages. Forests in the damaged area of five hectares were Scots pine (Pinus sylvestris L.) dominated and 60-80 years old. According to the factory, the exhaust gases contained 0.4 mg chlorine per liter. In addition, chlorate containing liquids evaporated thorough the chimney, which seemed to have been the main cause of the damage. The chlorates may have concentrated in the snow covering the trees during the winter. The Scots pine trees had lost all the needles in spring, but grew new needles in the summer. In some trees the new needles were few or undeveloped. Some mild damages were noticed in pine and Betula sp. during the growing season. Forest edges and trees higher that the other trees were worst damaged. Pine was most sensitive to the emission. Pine weakened by the gas damages were attacked by insects, the most important being Pissodes sp. The secondary insect damage is likely to kill the surviving trees. The dying pines should be removed only if it is necessary to prevent the spreading of insect damage. The trees may hinder the spreading of further gas emissions. In future, other tree species should be preferred over pine.

The PDF includes a summary in German.

  • Kangas, ORCID ID:E-mail:
article id 4464, category Article
Esko Kangas. (1932). Tutkimuksia kaasutuhoista Imatran valtionpuistossa. Silva Fennica no. 23 article id 4464. https://doi.org/10.14214/sf.a9020
English title: Studies on gas damages in the state forests in Imatra.

A forest damage was detected in spring 1931 near electro-chemical factory in Imatra in Eastern Finland. It was deduced that it was caused by a gas discharge from the factory. A survey was made to describe the damages. Forests in the damaged area of five hectares were Scots pine (Pinus sylvestris L.) dominated and 60-80 years old. According to the factory, the exhaust gases contained 0.4 mg chlorine per liter. In addition, chlorate containing liquids evaporated thorough the chimney, which seemed to have been the main cause of the damage. The chlorates may have concentrated in the snow covering the trees during the winter. The Scots pine trees had lost all the needles in spring, but grew new needles in the summer. In some trees the new needles were few or undeveloped. Some mild damages were noticed in pine and Betula sp. during the growing season. Forest edges and trees higher that the other trees were worst damaged. Pine was most sensitive to the emission. Pine weakened by the gas damages were attacked by insects, the most important being Pissodes sp. The secondary insect damage is likely to kill the surviving trees. The dying pines should be removed only if it is necessary to prevent the spreading of insect damage. The trees may hinder the spreading of further gas emissions. In future, other tree species should be preferred over pine.

The PDF includes a summary in German.

  • Kangas, ORCID ID:E-mail:
article id 4458, category Article
Esko Kangas. (1931). Siikakankaan mäntytaimistojen tuhoista. Silva Fennica no. 17 article id 4458. https://doi.org/10.14214/sf.a8999
English title: Siikakankaan mäntytaimistojen tuhoista.

Regeneration of large open areas in dry mineral soil forest sites that usually grow Scots pine (Pinus sylvestris L.) have several problems. For instance, soil frost, snow, ground vegetation and dryness can prevent germination and growth of seedlings. The damages caused by insects and fungi in seedlings of a large burned area in Siikakangas in Southern Finland was studied. A forest fire burned the area nearly completely in 1909, and 310 hectares have been sowed or planted with mostly Scots pine during the following years. Minor areas have been regenerated with Pinus montana Noll, Pinus excelsa Lamb., Pinus murrayana Balf. and Larix sibirica Ledeb.

No completely healthy pine seedling stands could be found in the area. About 41% of the seedlings in the sample plots were damaged. The most common causes for damage were Evetria resinella (now Retinia resinella L.), Luperus pinicola (now Calomicrus pinicola (Duft.)), Pissodes notatus (now Pissodes castaneus Degeer), Evetria turionana Hb. and Hylobious abietis L. The most usual fungal disease was Lophodermium sp. Evetria resinella caused damages in all the area. Evetria turionana, Pissodes notatus and Hylobius abietina were found in the older seedling stands. Other damages were more localized. The slacks in the terrain seemed to have most damages, the original cause being probably soil frost. Some damages, as Lophodermium, were related to the density of the seedlings, especially in the sown areas. Cleaning of seedling stands could decrease these damages. Planting seems to have succeeded better than patch sowing.

The PDF includes a summary in German.

  • Kangas, ORCID ID:E-mail:
article id 4458, category Article
Esko Kangas. (1931). Siikakankaan mäntytaimistojen tuhoista. Silva Fennica no. 17 article id 4458. https://doi.org/10.14214/sf.a8999
English title: Siikakankaan mäntytaimistojen tuhoista.

Regeneration of large open areas in dry mineral soil forest sites that usually grow Scots pine (Pinus sylvestris L.) have several problems. For instance, soil frost, snow, ground vegetation and dryness can prevent germination and growth of seedlings. The damages caused by insects and fungi in seedlings of a large burned area in Siikakangas in Southern Finland was studied. A forest fire burned the area nearly completely in 1909, and 310 hectares have been sowed or planted with mostly Scots pine during the following years. Minor areas have been regenerated with Pinus montana Noll, Pinus excelsa Lamb., Pinus murrayana Balf. and Larix sibirica Ledeb.

No completely healthy pine seedling stands could be found in the area. About 41% of the seedlings in the sample plots were damaged. The most common causes for damage were Evetria resinella (now Retinia resinella L.), Luperus pinicola (now Calomicrus pinicola (Duft.)), Pissodes notatus (now Pissodes castaneus Degeer), Evetria turionana Hb. and Hylobious abietis L. The most usual fungal disease was Lophodermium sp. Evetria resinella caused damages in all the area. Evetria turionana, Pissodes notatus and Hylobius abietina were found in the older seedling stands. Other damages were more localized. The slacks in the terrain seemed to have most damages, the original cause being probably soil frost. Some damages, as Lophodermium, were related to the density of the seedlings, especially in the sown areas. Cleaning of seedling stands could decrease these damages. Planting seems to have succeeded better than patch sowing.

The PDF includes a summary in German.

  • Kangas, ORCID ID:E-mail:

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