Abstract
We reanalyzed the data in Inoue et al. (1973) to evaluate the factors affecting carbon accumulation and nitrogen dynamics in brown forest soils under Japanese cedar (Cryptomeria japonica D. Don) and Hinoki cypress (Chamaecyparis obtusa Endlicher) stands in the Shikoku district. Soil properties were predicted from climate, tree species, and soil types using multiple regression analysis. Carbon concentration in the surface horizon and carbon accumulation in the soil profile were lower in warmer areas, and were not significantly related with mean annual precipitation. Higher temperature may enhance decomposition rates of organic matter and reduce carbon accumulation in soil. In surface soil, temperature was the primary factor controlling soil carbon accumulation, while in the deeper soils, the effects of soil type and tree species became stronger. The C/N ratio in the surface horizon was higher in dry soil type than in moist soil type, and in areas where mean annual precipitation was high. The C/N ratio in the surface horizon was negatively correlated with carbon accumulation in the profile. The slow decomposition rate at the surface horizon related to low nitrogen availability, may reduce movement of organic matter down to deeper horizon.
