In the year 2008 the stormy wind in central Slovenia destroyed more than 500,000 m3 of wood mass at an area of 20,000 hectares. 700 hectares of forests were completely destroyed. This research focuses on the mountain pass Črnivec area (the forest economic unit Gornji Grad in the forest economic area Nazarje). 320 permanent sample plots (PSP) were analysed with multi-version methods and logistic regression to collect data on trees and forest stands. The aim was to find out which characteristics of sites and stands have influence on the scale and level of damage on stands, as well as give recommendations concerning the reduction of high winds hazard in forest management. The data from PSP and other material (stand map, air photos, damage map) was obtained from the Slovenian Forest Service, regional unit Nazarje. The windfall occurrence model includes seven of twenty-seven variables: altitude, location, incline, wood stock of spruce, fir and beech, and bedrock. The most important among them is the bedrock, since the chance of windfall decreases for a quotient of 0.37 on a silicate ground. Another important factor is the location; the chance of windfall is 1.48 higher at the windward side then at the leeward side. The results show that the damage level on stands with more deciduous trees is far lower.
|