The influence of the forest management in the Białowieża forest on the species structure of the forest community.
Saving Europe's remaining natural forests is one of the main objectives of the political challenges to stop the ongoing decline of biodiversity. Conservationists and foresters need objective data to assess the success or failure of management actions to conserve biodiversity. Comparing the structural characteristics of forest communities that have been subjected to or excluded from forest management, and whose history is well known, makes it possible to assess the effects of anthropogenic pressures on biodiversity. One object that creates such opportunities is the Białowieża Forest (BF). Here, for the first time, a systematic sample of information on forest communities has been objectively collected to assess the impact of different management/protection regimes on the richness and species composition of forest communities. Species of vascular plants, bryophytes, liverworts, and epigeic lichens were recorded in the 1370 sample plots distributed in a grid of 650 × 650 m during years 2016-2018. The average number of plant species recorded in the 400 m2 sample plots was compared according to the following protection categories: Orłówka protection district (Orłówka PD) of the Białowieża National Park (BNP), which has been subject to strict protection since 1921 - 5.1 thousand ha, Hwoźna protection district of the BNP (Hwoźna PD), which has been under partial protection since 1996 - 5.1 thousand ha, nature reserves - 12 thousand ha, and commercial forests - 38.2 thousand ha. In terms of species richness, the commercial forests had on average, 4 fewer species than the Hwoźna PD, but did not differ significantly in this respect from the other protection categories. In the relevant forests in Orłówka PD, there were on average 4 species of bryophytes and lichens more than in the commercial forests, and this difference proved to be statistically significant. Based on rarefaction curves, the more species-rich contexts were commercial forests in all the trophic and humidity categories. From this study, it emerged that the differences in flora between the managed and strictly protected part of the BF are small and limited to some plant groups. However, this principle does not apply to bryophytes and non-native species.