热带季节雨林与人工橡胶林土壤碳氮比较

选取我国西南部西双版纳地区的热带季节雨林和人工橡胶林为对象，比较了2006—2007年两种土地利用方式下凋落物输入、土壤总碳氮含量及活性碳、氮的季节性变化.结果表明:与热带季节雨林相比，橡胶林的地上年凋落物量较低，而地面凋落物残留量较高，反映了橡胶林凋落物分解速率(凋落物消失率常数值，K )较低;橡胶林凋落物和土壤的C/N比值较高，暗示了其林内有机物的可降解性较热带季节雨林弱;橡胶林表层土壤总有机碳、生物活性有机碳和微生物生物量碳含量只有热带季节雨林土壤的60%～70%，硝态氮含量较少，pH 值则比热带季节雨林土壤低1.1.说明热带季节雨林转变为橡胶林后，林内地上凋落物向土壤输入的碳、氮量减少，土壤碳、氮含量和有效性降低，并且土壤呈现酸化倾向.应制定合理的橡胶林土壤管理措施，阻止土壤质量的下降趋势，以维持橡胶林的生产可持续性.

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%〖KG-*2〗-〖KG-*7〗70% of those in seasonal rain forest, and the soil NO3--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.