The European bison as seed dispersers: the effect on the species composition of a disturbed pine forest community

Abstract

We studied the process of change in plant species composition in a pine–spruce forest influenced by endozoochorous seed dispersal by the European bison Bison bonasus L. The intensity of endozoochory was 3.4 times higher in the open tree stand than in the surrounding undisturbed forest (t = –3.0836, df = 50, P = 0.003). Over 1578 individuals/ramets belonging to 23 vascular plant taxa developed on 114 bison dung piles. The process of colonization included two plant species that have never before been recorded in the studied forest community. Seven out of 14 species transferred by bison were small-seeded herbaceous plants without morphological adaptations for long-distance dispersal. The majority of plant species recorded on the bison dung (55.9%) occur in deciduous forests. In contrast, over 50% of the plants surrounding bison faeces represented species of coniferous forests. The PCA analysis revealed the existence of two distinct groups of plant species: within bison faeces and on random systematic samples. The Jaccard coefficient of species composition similarity between them was 0.28. Our results demonstrate that the European bison is an effective vector of plant propagules between plant communities. This fact could have great importance for the restoration of degraded habitats, and could also introduce the risk of invasion by alien species.