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Risk for snow-induced forest damage will increase in eastern and northern Finland while winters become milder

Risk for snow-induced forest damage will increase in eastern and northern Finland while winters become milder

The impact of climate change on the risk of snow-induced forest damage was studied in a joint study by the Finnish Meteorological Institute and University of Eastern Finland.

Snow accumulating on tree crowns can cause damage in forest and furthermore hamper power transmission when damaged trees broke or bend over power lines. In Finland, the heaviest snow loads accumulate typically to the trees on fell tops in the eastern and northern parts of the country. On the other hand, in these areas trees are better adapted for heavy snow loads than elsewhere in Finland and snow-induced forest damage can occur anywhere in the country. The accumulation of snow on tree crowns is most efficient when temperature at the time of precipitation is close to freezing point so that the form of snowfall is heavy wet snow. On locations at high elevation, also rime accumulation increases crown snow loads substantially.

Winters in Finland are projected to become milder due to climate change and at the same time wintertime precipitation is projected to increase. When considering the snow damage in forests, most important are changes in the occurrence of weather conditions favourable for accumulation of crown snow load. The results of this study indicate that the heaviest snow loads will become on average lighter in southern and western Finland during the present century. Notwithstanding, in eastern and northern Finland the risk for snow-induced forest damage is projected to increase. "In these areas, the winters will be still in the future cold enough so that most of precipitation will fall as snow, and while winters become milder, the accumulation of wet snow will become more frequent. In addition, increasing humidity will increase the frequency of weather situations favourable for riming over these areas which are susceptible for rime accumulation due to the topography. According to these results, the increasing risk of snow damage in forests should be taken into account in forest management in these areas", says researcher Ilari Lehtonen from the Finnish Meteorological Institute.

The study has received funding from the Academy of Finland through the ADAPT and FORBIO research projects.

More information:

Researcher Ilari Lehtonen, tel. +358 50 380 2870, ilari.lehtonen@fmi.fi

Lehtonen I, Kämäräinen M, Gregow H, Venäläinen A & Peltola H, 2016: Heavy snow loads in Finnish forests respond regionally asymmetrically to projected climate change. Nat. Hazards Earth Syst. Sci.16: 2259–2271.

http://www.nat-hazards-earth-syst-sci.net/16/2259/2016/nhess-16-2259-2016.html


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