Tree height and species composition of young forest stands fifteen years after the large-scale wind disturbance in Tatra National Park

In November 2004, the windstorm Alzbeta damaged over 12 thousand ha of forests in the High Tatra Mts. It was the largest wind disaster in the modern forestry history of Slovakia. The process of forest regeneration at the post-disturbance area has to be monitored together with the effectiveness of implemented forestry measures. Therefore, we focused on tree measurements at 90 monitoring plots (MP) in 1 x 1 km net placed in the post-disturbance area in the Tatra National Park. We recorded tree species, number of trees (density) and tree heights. Besides that, stem diameters of trees with breast height diameter over 7 cm were measured. The field work was performed in the growing season of 2019, i.e. about 15 years after the wind disturbance. In total, 20 tree species, 15 broadleaves and 5 coniferous ones, were recorded at MP. The most frequent (28.9% of all trees) species was Norway spruce followed by silver birch (18.6%), rowan (16.9%) and goat willow (15.2%). Four species, i.e. European larch, wild cherry, grey alder and common alder contributed to the total number of trees between 1.8 and 4.8% each. Share of all other species together was about 5%. Tree height frequency was left-sided for the whole sampling set (all species together), as well as for individual species. Most of young trees were less than 1m high, but some of them exceeded 10 m. Further, tree density of over 100 individuals per are (100 m(2)) was found at 1/3 of all MPs. As many as 25% of MPs were characterized with tree densities between 61 and 90 individuals. At 23% of MPs, the number of trees was up to 30 individuals per are, and 20% of MPs had between 31 and 60 small trees per are. The results suggested that the post-disturbance forest stands in the High Tatras would be more resistant to wind storms and very probably also to bark beetles after reaching maturity than those, which were destructed and declined at the beginning of 21st century.