Impact of the structure of different selection forest types on their wind resistance in High Tatra National Park

The paper evaluates the impact of two selection forest types with different tree species composition and their static stability against the windstorm that has affected the forest stands of High Tatra National Park in 2004 and uprooted more than 12 000 ha of the forest. The research objects were compartment 707 in protective district Vy né Hágy and compartment 12041 in protective district Ke marské aby. Studied stands had different tree species composition. In compartment 707, Norway spruce was the dominant tree species with the admixture of Silver fir and Scots pine. In compartment 12041, the Silver fir ratio reached 25% and Norway spruce as the main tree species accounted for 65%. In 1986 permanent research plots (PRP) of 0.25 ha were established in both compartments. This article reports the structure of both selection forests before the calamity (year 1996) and after it (year 2009). Despite the high values of the static stability indicator, which were in the stands nearly equal, the trees of the upper and middle layer were uprooted or broken. In both stands, the lower layer of selection forest was preserved. In compartment 12041, where the fir ratio in tree species composition of the selection forest was 25%, the current amount of fir in the next tree generation increased up to 41% after the windstorm. The regeneration processes in the selection forest structure were sufficient and created conditions for securing the following stand generation. The research results in both investigated stands showed, that the silvicultural interventions in the forests of High Tatra NP should form a selection or mosaic structure in the stands respectively. Their natural tree species composition creates good conditions for the application of close-to-nature management and the maintaining of the next forest generation without additional silvicultural interventions.