13 June 2020
Climate change induces multiple abiotic and biotic risks to forests and forestry. Risks in different spatial and temporal scales must be considered to ensure preconditions for sustainable multifunctional management of forests for different ecosystem services. For this purpose, the present review article summarizes the most recent findings on major abiotic and biotic risks to boreal forests in Finland under the current and changing climate, with the focus on windstorms, heavy snow loading, drought and forest fires and major insect pests and pathogens of trees. In general, the forest growth is projected to increase mainly in northern Finland. In the south, the growing conditions may become suboptimal, particularly for Norway spruce. Although the wind climate does not change remarkably, wind damage risk will increase especially in the south, because of the shortening of the soil frost period. The risk of snow damage is anticipated to increase in the north and decrease in the south. Increasing drought in summer will boost the risk of large‐scale forest fires. Also, the warmer climate increases the risk of bark beetle outbreaks and the wood decay by Heterobasidion root rot in coniferous forests. The probability of detrimental cascading events, such as those caused by a large‐scale wind damage followed by a widespread bark beetle outbreak, will increase remarkably in the future. Therefore, the simultaneous consideration of the biotic and abiotic risks is essential.
In Finland, projected climate change acts to increase forest growth by the mid‐21st century, particularly in the northern parts of the country. Nonetheless, in the south, the growing conditions may become suboptimal for Norway spruce due to drought and excessively high temperatures. Biotic damages, mainly caused by Spruce bark beetles and Heterobasidions, are anticipated to increase in southern Finland. Abiotic disturbances due to windstorms, drought and forest fires will be exacerbated especially in the south with snow damages in the north. Climate change likewise increases detrimental cascading events, for example, large‐scale wind damages followed by a widespread bark beetle outbreak.