Diversity of ground beetles (Col.: Carabidae) in managed and protected forest ecosystems in two mountain mesoregions in the Carpathians (south−eastern Poland)

In 2016−2017 and 2021 the trapping of epigeic fauna was done in the two mesoregions of southern Poland: in Beskid Niski and in Bieszczady Zachodnie. In both mesoregions the traps were located in the forests under nature protection (Magurski and Bieszczadzki National Parks and nature reserves outside) and in stands subjected to sustainable forest management. The trapping was done using inventory plots established in regular grid 1×1 km, although every second plot (pair number) was sampled. In total 585 plots were sampled. Pitfall traps (Barber type, one trap per plot) filled with 100 ml of ethylene glycol were installed in the centres of the plots. In total 41,656 beetles representing 81 species were collected. The diversity of ground beetles was assessed using 3 indices which included number of taxa, Shannon−Wiener index (species diversity) and Margalef index (species richness). The data from the traps in which the number of collected carabids did not exceed 50 individuals were excluded with 333 trapping plots used for analysis. The trapping done in large areas in two mesoregions of south−eastern Poland (Beskid Niski and Bieszczady Zachodnie) revealed higher diversity of ground beetles in the forest ecosystems subjected to forest management (number of taxa 11.23 and 11.18, Shannon−Wiener index 1.764 and 1.833, Margalef index 2.128 and 2.297, respectively) in comparison with those under nature protection such as the national parks and nature reserves (number of taxa 9.68 and 10.45, Shannon−Wiener index 1.631 and 1.728, Margalef index 1.953 and 2.111, respectively). In line with the results from the literature, the diversity of Carabids was higher in the forest ecosystems dominated by deciduous trees (in this case beech) than in the stands with higher representation of coniferous species (in this case mainly Scots pine). The representatives of protected or rare species were collected in various stands offering favourable conditions regardless their status (managed or protected). Our results indicate that sustainable forest management, without clearcuts, does not negatively affect the diversity of this group of insects. Conversely, forestry operations acting as a kind of disturbance stimulate the diversity of ground beetles. It is, however, not clear if such effect can be observed in the other groups of organisms as the response of ground beetles can be unique.