[Comparison of soil C and N in rubber plantation and seasonal rain forest].

With the rubber plantation and seasonal rain forest in Xishuangbanna of Southwestern China as test objectives, a comparative study was conducted on their litter input, soil total C and N contents, and seasonal changes of soil active C and N from 2006 to 2007. Comparing with seasonal rain forest, rubber plantation had lower amount of aboveground litterfall and higher amount of floor mass, reflecting the lower decomposition rate (turnover coefficient, K) of litters, and had higher C/N ratio of litters and soil, indicating that the organic matters in rubber plantation were more resistant to degradation. The surface soil total organic C, labile organic C, and microbial biomass C concentrations in rubber plantation accounted for 60%-70% of those in seasonal rain forest, and the soil NO3(-)-N concentration and pH value in rubber plantation were lower than those in seasonal rain forest, indicating that the conversion from seasonal rain forest to rubber plantation decreased the C and N inputs from aboveground litterfall and the availability of soil C and N, and caused soil acidification. Moderate land management strategies for rubber plantations were needed to prevent the degradation of soil quality and to maintain the productive sustainability.