Abstract
This study clarified the present situation with respect to the effects of sika deer, Cervus nippon, on the forest vegetation in the Zenki region, Mt. Ohmine (Shimokitayama, Nara prefecture). The forest structure, deer population density, and dwarf bamboo, Sasa borealis, vegetation on the forest floor were surveyed. A forest census conducted in 2005 revealed that the size structure of 1443 stems over 1.3m in height showed an inverse-J shape in the 1.08-ha plot. Bark-stripped stems (≥5cm in diameter at breast height) were seen in 18 of 54 species (33.3%) and 144 of 1023 trees (14.1%). The population densities of sika deer in September and October 2008, estimated based on the fecal accumulation rate tecnique, were 11.2 and 24.0 head/km^2, respectively. The mean stem density of S. borealis was 0.0023±0.0159 stem/m^2 (mean±1SD, n=432) in 2009. In comparison with the density recorded in 1983 around the study plot (11.3±5.7 stem/m^2, n=184), the S. borealis vegetation had declined markedly. Therefore, we postulate that sika deer severely affected the forest floor vegetation, i.e., S. borealis vegetation, tree regeneration, and herbaceous plant growth.
