The factors that determine the intensities of deer browsing and debarking on broadleaf tree around artificial grasslands

In the recent years, the deer browsing and debarking became the serious problem for forest regeneration, due to their direct damage on trees and saplings and/or the indirect effects through the domination of unpalatable understory vegetation. The intensities of browsing and debarking are affected by various factors, including region-specific vegetation features: for example, the understory cover by dwarf bamboo, which is tolerant for deer browsing, is common in Japanese temperate forests. However, the effects of these factors have rarely been examined at the same time. In the present study, we examined the effects of tree size, tree species, the distance from artificial grasslands, and the domination of dwarf bamboo on the intensities of browsing and debarking by sika deer (Cervus nippon) in broadleaf deciduous forests surrounded by artificial grasslands in Yamanashi Prefecture, central Japan. The occurrence probability of debarking was high in forests located near artificial grasslands and differed greatly by tree species. Maximum height and coverage of dwarf bamboo were not affected by the distance from the nearest artificial grassland. The numbers of saplings were low in the forests located near artificial grasslands and with tall dwarf bamboo. The occurrence probability of browsing on saplings was low in the forests with tall dwarf bamboo. Our study showed that the intensities of deer browsing and debarking were severe near artificial grasslands because the attraction of deer and the domination of unpalatable dwarf bamboo were affected by tree size and its species.