Badger Meles meles setts and bryophyte diversity: A newly found role for the game animal in European temperate forests

Badgers (Meles meles) inhabiting Central European forests may be a leading factor driving changes in plant species community and diversity. The digging activity of badgers may shape plant species communities in important ways, especially in managed forests where natural events on the forest floor (e.g. soil disturbance due to tree uprooting) are largely eliminated by silviculture. We tested the following hypotheses in our study: that badger burrows act as focal sites which allow many bryophyte species to occur and complete their reproductive cycle; that the effect of burrows as focal sites of bryophyte diversity is more pronounced in mesotrophic forests than in fertile forests; and that the bryophyte communities of badger burrows differ quantitatively and qualitatively from those of their near vicinity. The study was done in 2013 in the Kampinos Forest, one of the largest (ca. 385km2) lowland forest complexes in central Poland. We distinguished two types of research sites: badger burrows (main setts) and paired reference plots. The pairs of plots were divided into two groups depending on habitat fertility (C/N ratio): lower-fertility plots (N=20) and higher-fertility plots (N=20). All data were collected from circular plots (5.64m radius); the burrow plots were centered on the badger burrows and were paired with same-size reference plots. We recorded 55 bryophyte species in the survey, 26 of them exclusively on burrows. The beta diversity of the bryophyte assemblages, expressed as total dissimilarity, turnover and nestedness, was similar for the burrows and the reference plots. The mean number of bryophyte species and their Shannon H′ diversity index were significantly higher for burrow plots than for undisturbed reference plots. Neither the number of species nor the species diversity of bryophytes were affected by the interaction of habitat fertility. We observed no relation between the profile of bryophyte groups on the burrows and specific substrate, acidity or life history. Only epiphytic bryophytes were overrepresented in burrow plots. The spatial scale and range of disturbance caused by badger digging suggest that badger setts contribute to the diversity of bryophyte species in managed and protected forests in Central Europe. The burrowing activity of badgers seems to be an important factor boosting the diversity of bryophyte species in managed forests, especially where natural topsoil disturbances are limited by silviculture practices. In forest ecosystems, badger activity creates a patch distribution of microhabitats for vascular plants – and also for bryophytes, as shown here.