Bark-stripping by Sika deer (Cervus nippon) in Nara Park, Japan

Abstract

We investigated bark-stripping by Sika deer (Cervus nippon) in the forest at Nara Park, which is inhabited by more than 1200 deer. We found bark-stripping in 33.8% of 1041 trees more than 1.3m in height. Among the 39 tree species recorded in 10 areas, 31 species were found to suffer various degrees of bark-stripping. The species most preferred by the deer were Lagerstroemia indica, Viburnum awabuki, Podocarpus macrophyllus, and Pieris japonica, whereas those less preferred were Prunus mume, Carpinus tschonoskii, Ginkgo biloba, Quercus myrsinaefolia, Sapium sebiferum, Zelkova serrata, and Pinus thunbergii. The frequency distribution of trunk diameter at breast height (DBH) of trees suffering from bark-stripping indicated a reverse J-shaped distribution. However, bark-stripping was performed randomly within each species, regardless of DBH. This suggests that bark-stripping by Sika deer depends on bark preference rather than DBH size. In each plot, the proportion of non-preferred trees increased with increasing distance from the Kasugayama Forest Reserve and/or Wakakusayama Hill, and decreased with increasing distance from the urban areas. The relationship between the spatial environmental gradient and bark-stripping by Sika deer suggests that regional conservation is necessary for the management of vegetation and the high-density Sika deer population in Nara Park.