Effects of browsing by sika deer (Cervus nippon) on subalpine vegetation at Mt. Kita, central Japan

The effects of browsing by sika deer ( Cervus nippon ) on subalpine vegetation ( Betula forests and tall grasslands) were investigated in the South Alps National Park, Japan. The browsing ratio (the number of browsed quadrats to the number of quadrats occurring in each plot) was significantly higher in Betula forests than in grasslands. A significant negative correlation was found between the browsing ratio and some species diversity indices (number of species and the Shannon–Wiener diversity index) in the Betula forests, but not in grasslands. The frequency of occurrence and the number of preferred browse species were significantly higher in Betula forests than in grasslands. Browsing was not always the most serious on the most frequent vegetation. For example, Polemonium caeruleum L. subsp. yezoense var. nipponicum , which is listed as vulnerable on Japan’s red list of threatened species and was low in occurrence in Betula forests compared to grasslands, was more browsed in Betula forests than in grasslands. Less frequently occurring species subjected to more browsing could easily disappear. The disappearance of such species would exert a strong effect on the species pool in the area.