Title : Impact of wild boar rooting on a soil seed bank of oak-linden-hornbeam forest in the Bialowieza Forest
The wild boar is an omnivorous animal, and by foraging (rooting) disturbs the topsoil layer. In some regions of Poland and Europe seasonal fluctuations in rooting have been observed. Wild boars not only eat plants but also strongly modify their habitat. In Bia?owie?a Forest wild boar most frequently visit oak-hornbeam forests growing on fertile soil. On sites where the forest floor is covered with dense vegetation germination of seeds is difficult, and wild boar rooting can promote the removal of diaspores from deeper layers of the soil seed bank. The aim of this study was to assess the impact of wild boar rooting on the soil seed bank in a natural oak-linden-hornbeam forest. Observations were carried out on permanent plots (100 squares of 8 m x 8 m) in the strictly protected zone of Bia?owie?a National Park (Bia?owie?a Forest). The Bia?owie?a Forest (62 219 ha) is the best-preserved forest ecosystem within the temperate zone in Europe and widely regarded as a model forest, related to observations and research into pristine deciduous and mixed forests. Samples of the soil seed bank were taken from plots which showed varying intensities of wild boar rooting (frequency and an average percentage of an exposed ground surface). Areas to be sampled were selected on the basis of archival data. Squares were divided into low (series A), medium (series B) and highly rooted (series C). The series of squares significantly (P<0,001) differed in their intensity of rooting. The research was conducted by the seedling emergence method during two vegetation seasons. Altogether, 7985 seedlings (of 67 taxa) germinated from 240 soil samples. The highest number of germinated seedlings and species were found in the highly rooted squared. In all the series dominant species was Urtica dioica. In the soil seed bank, 19 species of anemochory germinated and accounted for 27.5% of all species present in the seed bank of all series. Permanent wild boar rooting increased the species richness in the soil seed bank and increased the number of species with higher light requirements.