Debarking intensity of European bison in the Bieszczady Mountains in relation to forest habitat features

Abstract

The damage to trees that is caused by ungulate species is a natural result of their presence in ecosystems. High densities of ungulates may have a negative effect on biodiversity and the regeneration and survival of trees. The aim of this study was to identify the factors that affect the probability of the occurrence of damage in forest stands as a result of the presence of European bison (Bison bonasus). We collected data on the presence of European bison in given locations in winter and spring of 2020; this data also concerned damage to trees, forest stand characteristics, and densities of other ungulates.European bison was the most important debarking agent. Within the home range of the European bison, 344 forest stands were damaged, which represented 43.5% of all stands. The most frequent damage was bark stripping, 35.9%. The most important factors in terms of bark damage were canopy cover, dominating tree species, dominating tree age, and distance to a feeder. More debarking occurred in stands with open canopies, and coniferous species were more likely to be damaged than broadleaved species. Frequency of damage in forest stands with dominating Norway spruce was higher than 0.5, whereas for forest stands with silver fir and Scots pine it was over 0.4. Other coniferous species also presented a relatively high proportion of damage (0.38). The results of our study indicate a need for rational damage-prevention measures in the ranges of other free-living wisent populations that live in managed forests.