Spatiotemporal pattern of wild boar rooting in a Central European dry oak forest

Abstract

Wild boar (Sus scrofa) density has significantly increased worldwide. In Europe, oak acorns are basic diet items for the species. However, regeneration of temperate oak forests has become excessively low. Thus, better understanding of the patterns and dynamics of wild boar rooting and the spatiotemporal relationship between the acorn density and the rooting has special importance. In our study, the acorn density, the presence and intensity of the rooting were measured monthly in a 28-ha oak forest stand between 2016 October and 2019 April. Study site was divided to 400 m2 grid cells to investigate the spatiotemporal patterns of the rooting. Comparing the acorn densities, we stated that in the first 2 years, but not in the third one, the oaks were masting. During the acorn-rich periods (October–April), significant inter-annual differences were found in the proportions of the disturbed area between the non-mast and the other two mast years. Throughout our observations, 9.12% of the cells stayed undisturbed. On average, in 12.59% of the cells new rooted patches appeared, and 15.6% of them was repeatedly disturbed. Rooting were mainly litter disturbances in 71.75% of cases. Throughout acorn fall periods (September–November), the most intensively rooted sites were the poorest in acorns, while the unrooted sites were the richest. Our results demonstrate that wild boars have a great effect on acorn density and on the whole forest by rooting almost the entire ground surface at least once, but also the masting of the oaks has a crucial role in their rooting dynamics.