Effects of deer grazing on soil C and N dynamics in Miscanthus sinensis grassland and Quercus serrata forest in Ashiu research forest, Japan

Abstract

ABSTRACTTo elucidate the grazing-induced changes in soil nutrient cycling, we compared vegetation and soil C and N dynamics, including inorganic N content and total C and N contents, among four plots: Quercus serrata plots inside and outside of a deer exclusion fence and Miscanthus sinensis plots inside and outside of the fence. A linear model with stepwise procedures was used to assess the effects of vegetation type, deer grazing, and soil layer. In the fenced M. sinensis plot, soil C and N contents were higher than in the other plots in autumn. This is likely because the mass of litter from regenerating herbaceous plants was about three times larger than that from Q. serrata. Regardless of the presence of Q. serrata canopy, soil contents were significantly higher outside the fence than inside during the observation periods, whereas the net nitrification rate showed the opposite trend in the summer. The result indicates that N uptake by herbaceous plants is effective in retaining in the fenced plots. In our study site, the regenerating herbaceous plants, especially M. sinensis, would play a greater key role in C sequestration and retention in the surface soil than do the canopy tree Q. serrata.