Impacts of the sika deer on montane and subalpine grasslands in Chichibu-Tama-Kai National Park and surrounds, central Japan

Abstract

We investigated the impact of the sika deer (Cervus nippon) on plant species composition in montane and subalpine grasslands in the Chichibu-Tama-Kai area, Yatsugatake area, and Minami-Alps area, central Japan. In 2008, we resampled 61 releves which had been sampled in the 1980s and counted the number of fecal pellets of the sika deer in a given grassland. We found that the number of fecal pellets of the sika deer in 2008 was positively associated with the change from the 1980s to 2008 in the axis 1 score of detrended correspondence analysis of species composition; the utilization of grasslands by the sika deer was the greatest factor to determine the change in species composition. Moreover, sika deer positively utilized grasslands in regions with shallow snow cover in winter and inhabited areas away from buildings. Plant species richness changed from increase to decrease with increasing utilization by the sika deer. Increase of the impact of the sika deer was accompanied by retrogression of vegetation cover, which led to woody species invasions and an increase of cover in species tolerant to grazing.