Risk of the wind damage to the forests in Poland on the basis of a stand damage risk model

On the basis of the wind damage risk model for forests using the data of the State Forests Information System, the stand damage risk factor W-r for each of the 430 forest districts in Poland and the threat measure M-s for a given forest district were determined. The measure of threat to forest M-s for a forest district is a methodical basis for assessing the potential damage to forests in Poland. Its value ranges from 8.1% for the Brzozka Forest District to 48.9% for the Ujsoly Forest District (fig. 1), giving the average value of 24.6% and standard deviation of 7.03%. The measure M-s was the basis for differentiating the levels of threat of wind damage to forest for forest districts. Level 1 (M-s <= 10%) indicates low threat, level 2 (10%<M-s <= 20%) - elevated threat, level 3 (20%<M-s <= 30%) - moderate threat, level 4 (30%<M-s <= 40%) - high threat, level 5 (M-s>40%) - very high threat. Low threat to forests was found only in two forest districts located in the western part of the country. 113 forest districts, which form large concentrations particularly in western and central Poland, are exposed to an elevated threat. Most forest districts (233) are classified to a group of moderate threat. They are located across the country and are mostly concentrated in the northern and southern regions of Poland. 71 forest districts exposed to high threat are concentrated in the south of Poland in the Carpathians and the Sudetes, with scattered presence in the north of the country. Most of the 11 forest districts with a very high threat to forests are located in the mountains (tab., fig. 1). For the forest districts with a particularly high and very high threat, new silvicultural procedures and the basis for decision making in the field of forest management should be developed to reduce the risk of damage to forest.