Impacts of climate change on the risk of snow-induced forest damage in Finland

Abstract

This work studied the temporal and spatial variability of the risk of snowinduced forest damage in Finland under current and changing climatic conditions until the end of this century. The study was based on a snow accumulation model in which cumulative precipitation, air temperature and wind speed were used as input variables. The risk was analyzed in terms of the number of days per year when the accumulated amount of snow exceeded 20 kg m −2 . Based on the risk, the forest area and mean carbon stock of seedling, young thinning and advanced thinning stands at risk were calculated. Furthermore, the number of 5-day periods, when the accumulated amount of snow exceeded a risk limit, was calculated for the current and changing climatic conditions in order to study the frequency of damaging snowfalls. Compared to the baseline period 1961-1990, the risk of snow-induced forest damage and the amount of damaging snowfalls were predicted to decrease from the first 30-year period (1991-2020) onwards. Over the whole country, the mean annual number of risk days decreased by 11%, 23% and 56% in the first, second and third 30-year period, respectively, compared to the baseline period. In the most hazardous areas in north-western and north-eastern Finland, the number of risk days decreased from the baseline period of over 30 days to about 8 days per year at the end of the century. Correspondingly, the shares of the forest area at risk were 1.9%, 2.0% and 1.0% in the first, second and third 30-year period, respectively. The highest mean annual carbon stocks of young stands at risk were found in central, north-eastern and north-western Finland in the first and second 30-year period, varying between 0.6 and 1.2 Mg C ha −1 year −1 , meaning at highest 3% of the mean carbon stock (Mg C stem wood ha −1 ) of those areas. This study showed that although the risk of snowinduced forest damage was mainly affected by changes in critical weather events, the development of growing stock under the changing climatic conditions also had an effect on the risk assessment. However, timely management of forest stands in the areas with a high risk of snow-induced damage contributes to the trees' increased resistance to the damage.

Recent Change—Terrestrial Cryosphere

“…According these criteria, snow-induced forest damage was expected in Finland on average 65 times a year during the period 1961-2000, but as often as 150 times a year during the mild 1990s. During 1961-2000, the maximum number of heavy snow-load events occurred in 1994 in northern Finland (Gregow et al 2008;Kilpeläinen et al 2010). …”

Multiple Effects of Changes in Arctic Snow Cover

“…A modelling assessment of risk projected that compared with the baseline period 1961-1990, the amount of damaging snowfalls and risk of snow-induced forest damage will decrease, particularly in the north of Finland (Kilpelainen et al 2010).…”

Arctic Societies, Cultures, and Peoples in a Changing Cryosphere

“…Snow is an important factor in forest damage (Kilpelainen et al 2010). Heavier snowfalls and icing crush tree canopies and hinder new growth.…”