Abstract
Ohdaigahara, one of the largest natural forests in south-western Japan, is now facing to the danger of vegetation collapse because of high density of deer. In the Fagus crenata-Abies homolepis-Sasa nipponica community, one of the main vegetation communities in Ohdaigahara, we conducted field experiments with manipulations of deer and mice, and studied the influence of deer and mice on aboveground and underground parts of S. nipponica. Under browsing pressure by deer, the aboveground part of S. nipponica was dwarfed and the biomass was small. On the contrary, the underground biomass was larger and the rhizome was longer. It seems that S. nipponica under browsing pressure by deer relatively invests to the underground part to spread under ground. Under browsing pressure by mice, on the other hand, S. nipponica produced a rhizome with lots of short internodes. In deer exclosures, the aboveground biomass of S. nipponica showed an increase over a three-year-and-ten-month period. However, the recovery during that period seemed not enough. More investigations about the interactions among other creatures and factors will help us to reveal the network of the lower part of the forest, and to present effective proposals for restoring the Ohdaigahara forest.
