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Bark beetle (Ips typographus) outbreaks have the potential to damage large areas of spruce-dominated forests in Scandinavia. To define forest management strategies that will minimize the risk of bark beetle attacks, we need robust models that link forest structure and composition to the risk and potential damage of bark beetle attacks. Since data on bark beetle infestation rates and corresponding damages does not exist in Norway, we implement a previously published meta-model for estimating I. typographus damage probability and intensity. Using both current and projected climatic conditions we used the model to estimate damage inflicted by I. typographus in Norwegian spruce stands. The model produces feasible results for most of Norway's climate and forest conditions, but a revised model tailored to Norway should be fitted to a dataset that includes older stands and lower temperatures. Based on current climate and forest conditions, the model predicts that approximately nine percent of productive forests within Norway's main spruce-growing region will experience a loss ranging from 1.7 to 11 m3/ha of spruce over a span of five years. However, climate change is predicted to exacerbate the annual damage caused by I. typographus, potentially leading to a doubling of its detrimental effects. [ABSTRACT FROM AUTHOR]

Sitka spruce (Picea sitchensis (Bong.) Carr.) was introduced in Atlantic Europe in the nineteenth century. Forests of this species are the major forest type in the United Kingdom and Ireland, with substantial areas in Norway, France and Denmark. Most forests are managed under a patch clearfelling regime on comparatively short (35-50 years) rotations. However, forest policies in a number of countries seek to increase the structural and species diversity of Sitka spruce forests: such measures are also proposed to help adapt to projected climate change and management of climate risk. Datasets from 26 experimental plots in Atlantic Europe representing existing and alternative management approaches showed high carbon stocks under current management and lower stocks in all alternatives. In addition, there was little evidence of Sitka spruce being grown successfully in long-term intimate mixture. Thinning is required to increase the diversity of Sitka spruce forests, but this can result in increased risk of wind damage, and hence reduction in carbon stocks, other than on the most sheltered sites. Such risks will be higher with the wetter soils anticipated from greater winter rainfall. Future management of Sitka spruce forests for carbon sequestration should focus both on improvement of current management (e.g. use of higher-yielding genotypes) and on developing wind-stable stands through careful thinning to act as long-term carbon stores. [ABSTRACT FROM AUTHOR]

An international Expert Panel was established in 2007 to undertake an assessment of the impacts of climate change on forests and forest-dependent people as well as on management and policy options for effective adaptation to climate change. This paper summarizes the main findings of the assessment, which has also revealed severe limitations in current knowledge. Much more research is needed, especially on the forest-related social and economic impacts of climate change. Despite the limitations of current knowledge, climate change is progressing too quickly to postpone actions pending the outcomes of future studies. The assessment confirms that the practices associated with sustainable forest management are likely to help reduce environmental, social and economic vulnerabilities under a wide range of potential future climatic conditions. [ABSTRACT FROM AUTHOR]

This paper presents the results of investigations of tree-ring growth in Dahurian larch (Larix cajanderi Mayr.) and Scots pine (Pinus sylvestris L.) in Central Yakutia, Eastern Siberia. The study used dendrochronological methods to analyse the influence of climate on tree growth and forest development in a permafrost area. Three larch sites and one pine site were investigated. The duration of tree-ring chronologies at all four sites was more than 200 years. Analysis of soil temperature influences on radial increment was carried out for the period from 1934 to 2006. For dependence of larch growth from soil moisture content on different depths, the data since 1988 were used. The study demonstrated that tree growth was largely dependent on soil hydrothermal conditions. The results of statistical analyses indicated that the radial growth of Dahurian larch and Scots pine in Central Yakutia was significantly correlated with soil temperature and moisture at various depths. Correlations with soil temperature at the different depths were 0.4-0.5 (p<0.05), especially during the winter period. Negative correlations with soil temperature were revealed in summer on the dry sites. Taking into account the droughty climate of Central Yakutia, soil moisture correlates well with the radial increment of trees (up to r=0.8, or higher). The highest correlation was revealed with the last year's autumn soil moisture. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the impacts of elevated carbon dioxide (CO 2 ) and temperature on the establishment, growth and mortality of the branches of Scots pine ( Pinus sylvestris L). In 1997, 16 young trees were individually enclosed in chambers, in eastern Finland, for a period of 5 years (1997–2001), in an environment that simulated the future climate for the region. There were four replicates of each treatment, including combinations of ambient and elevated CO 2 and temperature. Measurements were carried out on the establishment of new branches, branch diameter growth and branch mortality. Elevated temperature and elevated CO 2 had no positive effect on the number of branches that established each year or branch diameter growth. They were, instead, related to tree height growth and stem diameter growth, respectively. However, elevated CO 2 and temperature caused an increase in branch mortality. [ABSTRACT FROM AUTHOR]

Intraspecific variability in responses to temperature and shade was studied at Champenoux, north-eastern France, with seedlings from five Polish provenances of silver fir ( Abies alba Mill.). Acclimation of photosynthesis to temperature was investigated in seedlings exposed to 10, 25 and 35°C in a climate chamber for 1 week. During two growth seasons, a population of seedlings was grown in the nursery under four different irradiance regimens: 100, 48, 18 and 8% of natural irradiance. Maximum carboxylation rate ( V cmax ), maximum light driven electron flow ( J max ) and maximum net carbon dioxide assimilation rate ( A max ) measured at 25°C increased with population altitude. One week of exposure to 35°C caused discoloration and massive needle shedding. After 2 years’ acclimation to different levels of irradiance, a significant interprovenance variability was evidenced in growth, total biomass, biomass allocation and photosynthetic performance. This study provided evidence for the existence of functional variation among the examined provenances. [ABSTRACT FROM AUTHOR]

In this study, the snow and soil frost conditions in three different forest stand treatments in northern Sweden were investigated during winter and spring 1998/99. In total, 49 frost tubes and 25 snow gauges were used in one clear-cut area, one multilayered shelterwood of mixed Scots pine (Pinus sylvestris) and Norway spruce (Picea abies), and one single-layered shelterwood of old Scots pine. The snow cover was thicker and smoother and less soil frost was observed in the clear-cut area than in the shelterwoods. In the multilayered shelterwood the mean snow cover was shallower than in the single-layered shelterwood, but with larger spatial variation in snow depth related to the canopy density and with patches of snow and soil frost that lasted until early summer. Close to the shelter trees in the single-layered shelterwood the deepest soil frost was observed during the winter and early start of snow melting and soil frost thawing in spring. In conclusion, the snow and soil frost depths in the shelterwoods were related to the stem density. The single-layered shelterwood of large pines appeared to promote an earlier snowmelt and thawing of the soil frost than the multilayered shelterwood of mixed pine and spruce. [ABSTRACT FROM AUTHOR]