Recently, it's been a serious issue of many regions in Japan that sika deer (Cervus nippon centralis) declines vegetation due to its intensive grazing. It affects soil carbon (C) and nitrogen (N) dynamics through the dominance of plants with lower productivity.

In Ashiu research forest in Kyoto, deer grazing pressure has increased remarkably and drastically affected grassland ecosystem; where Japanese pampas grass (Miscanthus sinensis) was dominant up to 2000, has completely changed into rush (Juncus effusus var. Decipens) dominant grassland. We established an exclosure (750 m²) in 2008 to trace vegetation recovery, and observed restration of pampas grass.

Here, we studied the effect of exclosure on soil C and N dynamics associated with vegetation recovery. We took soil samples at 0-10 cm under organic layer inside and outside of the exclosure in May, Aug. and Dec. 2010, then measured soil moisture, NO₃^- and NH₄⁺ concentration, net mineralization and nitrification rates, soil C and N, soil pH and water extractable organic C and N.

We found soil NO₃^- was significantly lower in May and Aug. though nitrification was higher in Aug. and soil C and N were higher in Dec., in the exclosure. These results suggest that the plants with higher biomass in the exclosure absorbed more NO₃^- in growing season and supplied more fresh organisms as litter during senescence.