Effects of sika deer (Cervus nippon) and Sasa nipponica on the temperature and moisture of the surface soil on Mt. Ohdaigahara

Abstract

We examined the effects of Sasa (Sasa nipponica, a dwarf bamboo) grazed by deer (Cervus nippon) or removed artificially on the temperature and moisture regime of the surface soil in a temperate mixed forest at Ohdaigahara, in southern Honshu, using four types of experimental plot, and involving combinations of deer (excluded or present) and Sasa (removed or intact). More than half of the observed values of the matric potential of the surface soil ranged between -4 and 0 kPa in all treatment plots, although the soil moisture tended to be less humid in the deer-excluded/Sasa-intact plot than in the other plots. The monthly mean soil temperature in the deer-excluded/Sasa-intact plot was 1-2 degrees lower than that in the control plot in summer, and 1-2 degrees higher than that in the control plot in winter. These results suggest that the increase in the aboveground biomass of Sasa in the deer-excluded/Sasa-intact plot induces changes in soil temperature and moisture by increasing the cover and transpiration by the Sasa. However, the differences in the environmental changes between the plots were small and unlikely to have significant effects on litter decomposition and N mineralization in the soil. As a result, the observed change in the aboveground biomass of Sasa does not seem likely to influence the nutrient cycle in this forest by changing the temperature and moisture of the surface soil.