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Articles containing the keyword 'risk assessment'.

Category: Research article

article id 635, category Research article
Manfred J. Lexer, Karl Hönninger, Helfried Scheifinger, Christoph Matulla, Nikolaus Groll, Helga Kromp-Kolb. (2000). The sensitivity of central European mountain forests to scenarios of climatic change: methodological frame for a large-scale risk assessment. Silva Fennica vol. 34 no. 2 article id 635. https://doi.org/10.14214/sf.635
The methodological framework of a large-scale risk assessment for Austrian forests under scenarios of climatic change is presented. A recently developed 3D-patch model is initialized with ground-true soil and vegetation data from sample plots of the Austrian Forest Inventory (AFI). Temperature and precipitation data of the current climate are interpolated from a network of more than 600 weather stations to the sample plots of the AFI. Vegetation development is simulated under current climate (‘control run’) and under climate change scenarios starting from today's forest composition and structure. Similarity of species composition and accumulated biomass between these two runs at various points in time were used as assessment criteria. An additive preference function which is based on Saaty’s AHP is employed to synthesize these criteria to an overall index of the adaptation potential of current forests to a changing climate. The presented methodology is demonstrated for a small sample from the Austrian Forest Inventory. The forest model successfully simulated equilibrium species composition under current climatic conditions spatially explicit in a heterogenous landscape based on ground-true data. At none of the simulated sites an abrupt forest dieback did occur due to climate change impacts. However, substantial changes occured with regard to species composition of the potential natural vegetation (PNV).
  • Lexer, Institute of Silviculture, University of Agricultural Sciences, Peter-Jordanstrasse 70, A-1190 Vienna, Austria ORCID ID:E-mail: lexer@edv1.boku.ac.at (email)
  • Hönninger, Institute of Silviculture, University of Agricultural Sciences, Peter-Jordanstrasse 70, A-1190 Vienna, Austria ORCID ID:E-mail:
  • Scheifinger, Institute of Meteorology and Physics, University of Agricultural Sciences, Türkenschanzstrasse 18, A-1180 Vienna, Austria ORCID ID:E-mail:
  • Matulla, Institute of Meteorology and Physics, University of Agricultural Sciences, Türkenschanzstrasse 18, A-1180 Vienna, Austria ORCID ID:E-mail:
  • Groll, Institute of Meteorology and Physics, University of Agricultural Sciences, Türkenschanzstrasse 18, A-1180 Vienna, Austria ORCID ID:E-mail:
  • Kromp-Kolb, Institute of Meteorology and Physics, University of Agricultural Sciences, Türkenschanzstrasse 18, A-1180 Vienna, Austria ORCID ID:E-mail:

Category: Review article

article id 695, category Review article
Marja-Leena Päätalo. (1998). Factors influencing occurrence and impacts of fires in northern European forests. Silva Fennica vol. 32 no. 2 article id 695. https://doi.org/10.14214/sf.695
The return interval and number of fires vary, depending on the geographical location in interaction with climate, topography and amount of fuel. During recent decades, in northern Europe the number and severity of fires have been insignificant compared with Mediterranean region, in which fire return intervals may be 15–35 years, compared to the average of 60–120 years for boreal forests. This is partly due to the efficient system of fire protection in northern Europe, but is mainly due to the less favourable climate for fire and the smaller human impact on ignition of forest fires. The consequences of fire are related to both site and stand characteristics, site being the most important factor controlling the stability of stands. Dry sites being more flammable and likely to ignite are associated with high risk of fire. In northern Europe, due to the interaction between species and site, the role of species difference in risk of fire damage is not clear. In southern Europe, fire risk cannot be explained by differences between tree species. There, other vegetation (shrubs, etc.) is of major importance for the risk of fire. Management of forests can, to some degree, alter the risk and the occurrence of fire. In northern Europe, logging may have compensated for fire occurrence by decreasing the amount of fuel. In addition, forest roads act as fire-breaks and facilitate fire-fighting. On the contrary, in southern Europe the risk of fire has been found to increase because the traditional forest uses and management have decreased, which increases the accumulation of fuel. However, it is not yet possible to quantify and compare the effect of management in absolute terms. Currently, some tools, such as fire-risk indices, remote sensing and GIS-based techniques, are available for prediction of fire risk in some areas. For example, fire-risk indices are most suitable for areas, like northern Europe, which have a low fire risk. In high-risk areas, such as southern Europe, more sophisticated techniques are needed for assessment of the risk. In the future, assuming global warming at northern latitudes (2 x CO2 climate), the risk of fire damage could also increase in northern Europe. Therefore, to allow the various locational and silvicultural factors to be assessed on the European level, an integrated risk model is needed.
  • Päätalo, Faculty of Forestry, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland ORCID ID:E-mail:

Category: Article

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:

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