Model computations on the climate change effects on snow cover, soil moisture and soil frost in the boreal conditions over Finland

Abstract

This study considered how climate change affects the accumulation of snow, the soil moisture and soil frost at sites without tree cover in boreal conditions in Finland (60°-70°N). An increase of 4.5 °C in annual mean temperature and 20 % in annual precipitation were assumed for Finland by the year 2100 according to A2 emission scenario. Along with climate, the soil type of the permanent inventory plots of the Finnish National Forest Inventory was used. Soil and climate data were combined by using a process-based ecosystem model. Calculations were done for four periods: current climate , near future (2001-2020), mid-term future (2021-2050) and long-term future (2071-2100). According to our simulations, the average monthly duration and depth of snow decreased over the simulation period. However, the increasing precipitation may locally increase the snow depths in the mid-term calculations. In the autumn and winter, the average volumetric soil moisture content slightly increased in southern Finland during the near future, but decreased towards the end of the century, but still remained on a higher level than presently. In northern Finland, the soil moisture in the autumn and winter increased by the end of this century. In the summertime soil moisture decreased slightly regardless of the region. Throughout Finland, the length and the depth of soil frost decreased by the end of the century. In the south, the reduction in the depth was largest in the autumn and spring, while in the mid-winter it remained relatively deep in the middle of the century. In the north, the depth tended to increase during the first two calculation periods, in some areas, even during the third calculation period (2071-2100) due to reduced insulation effects of snow during cold spells. The wintertime increase in soil moisture and reduced soil frost may be reflected to reduced carrying capacity of soil for timber harvesting.

Projected decrease in wintertime bearing capacity on different forest and soil types in Finland under a warming climate

“…In accordance with previous studies (Venäläinen et al, 2001a(Venäläinen et al, , 2001bKellomäki et al, 2010), our results suggest that climate warming will lead to shorter soil frost periods reducing wintertime ground-bearing capacity. The projected decrease in the wintertime bearing season length was similar in the studied two climate model ensembles.…”

“…The climate warming is expected to be pronounced on high latitudes like in Finland (Räisänen and Ylhäisi, 2015;Ruosteenoja et al, 2016). Previous studies have indicated that the climate warming leads unsurprisingly to reduced soil frost depth and shorter soil frost periods (Venäläinen et al, 2001a(Venäläinen et al, , 2001bKellomäki et al, 2010;Jungqvist et al, 2014). This may shorten the winter harvesting season with good ground-bearing capacity, particularly on drained peatlands, having thus mainly negative impact on the forestry sector.…”

How can forage production in Nordic and Mediterranean Europe adapt to the challenges and opportunities arising from climate change?

“…On the other hand, increased precipitation in areas where temperatures remain below freezing can give longer-lasting snow cover in some areas (Johansson et al, 2011). Less snow cover can increase the occurrence, depth and duration of soil frost due to less insulation (Källomäki et al, 2010;Bjerke et al, 2015), and was shown to affect annual productivity of grasslands in Canada and Germany (Vankoughnett et al, 2016;Zeeman et al, 2017). There has been an increase in frequency of winter warming events in northern Norway, Sweden, and Finland during the last 50 years (Vikhamar-Schuler et al, 2016).…”

Integrating mechanistic disturbance models and stand dynamics of Norway spruce

“…Gonthier et al, 2005;La Porta et al, 2008;Müller et al, 2014). The effect of strong winds on forests is expected to increase due to the shorter frozen soil period that currently improve tree anchorage during the winter months (Blennow et al, 2010;Kellomäki et al, 2010;Gregow et al, 2011). Bark beetles are expected to benefit from the warmer temperatures by increased reproduction and having more generations with full life cycles (Bale et al, 2002).…”