中文摘要：

通过对江西泰和退化红壤区4种类型人工林（湿地松纯林、马尾松纯林、湿地松×枫香混交林以及枫香纯林）土壤各活性有机碳的含量测定，分析人工林类型及季节变化对土壤活性碳库的影响。结果表明：4种人工林的可溶性有机碳（ DOC）、易氧化有机碳（ ROC）、土壤微生物量碳（ MBC）的年平均值分别为52．67～105．17 mg/kg、6．68～13．33 g/kg、57．70～154．21 mg/kg。一年中4种人工林土壤DOC含量始终表现为：枫香纯林＞枫香×湿地松混交林＞马尾松纯林≈湿地松纯林；而ROC和MBC的年平均值则表现为枫香纯林≈枫香×湿地松混交林＞马尾松纯林≈湿地松纯林的趋势。各林地土壤的DOC、ROC、MBC含量具有明显的季节变化，基本变化趋势为夏、秋季大于冬、春季。

英文摘要：

This study was conducted in Taihe County ,a degraded red soil region in Jiangxi Province .It fo-cused on how plantation type and season affect the contents of soil labile organic carbon （ SLOC） .The contents of SLOC under pure forest of Pinus elliottii （Ⅰ） ,pure forest of Pinus massoniana （Ⅱ） ,mixed forest of P.el-liottii-L.formosana （Ⅲ） and pure forest of Liquidambar formosana （Ⅳ）,which were all built in 1991 were determined.The results showed that the contents of dissolved organic carbon （DOC）,readily oxidizable organic carbon （ROC）,and microbial biomass carbon （MBC） were in the ranges of 52.67~105.17,6.68~13.33 and 57.70~154.21 mg/kg,respectively.It was found that DOC decreased in the following order of Ⅳ〉Ⅲ〉Ⅱ≈Ⅰ,and the decreasing order of MBC and ROC was Ⅳ≈Ⅲ〉Ⅱ≈Ⅰ.The contents of DOC ,ROC and MBC with substantial seasonal fluctuations under different plantations were also observed .The soil DOC,MBC and ROC under the four plantations tended to be higher in summer and autumn than in spring and winter , which may be attributed to the climatic factors such as temperature and precipitation .