中文摘要：

采集湖泊自然湿地及其周边围垦农田的代表性土壤剖面样品,测定了总有机碳含量,讨论了天然淡水湿地围垦成农田后的土壤有机碳的变化。结果表明,湿地表层（0～15 cm）土壤有机碳含量范围为15.35～25.63g/kg;而农田表层土壤有机碳则为6.77～23.42g/kg。湿地开垦为农田后,土壤表层和全剖面的土壤有机碳含量明显降低,围垦到30-40年后,有机碳的损失趋于稳定,年均损失在1.04-1.06%之间。开垦为旱地土壤的有机碳含量和碳密度显著低于开垦为稻田,一年两季水稻田土壤有机碳含量和碳密度均高于一年一季稻。

英文摘要：

Samples of topsoil land soil profile are collected from both natural wetlands and the cultivated croplands. With the measurement of general Soil organic carbon（SOC） contents, the paper discusses the change in SOC of natural wetlands cultivated into farmland, and the results show that SOC storage from the topsoil at0-15 cm is15.35～25.63g/k, while SOC of farmland topsoil is 6.77～23.42g/kg. After wetlands cultivated into farmlands, SOC contents of topsoil and soil profile are obviously decreasing. After 30 to 40 years, loss of SOC tends to be stable, with annual loss between 1.04 %and 1.06%. SOC and carbon density of cultivated upland soil are lower than those of cultivated paddy, and SOC and carbon density of the paddy with two seasons crops a year are higher than those of the paddy with one season crop a year.