土地利用变化对土壤团聚体有机碳的影响

目的]探讨土地利用变化对土壤团聚体有机碳的影响。方法]利用团聚体分组方法，选择红树林湿地和农田（由湿地开垦为农田）为研究对象，分析湿地转变为农田后土壤团聚体有机碳的变化规律。结果]土壤团聚体主要分布在2000～250μm粒级中。质量分数为76．52％。土壤有机碳含量在团聚体中分配呈现了在2000—250μm粒级中最大，50～250μm次之，〈50μm团聚体最小的规律。土地利用变化对土壤团聚体有机碳具有明显的影响，对2000～250μm粒级团聚体的影响最为显著，50～250μm次之。土壤有机碳含量与2000～250μm和〈50μm团聚体有机碳含量达到了极显著水平，但同50～250μm粒级有机碳含量并无明显相关。结论]湿地开垦为农田后导致土壤团聚体碳库发生了显著变化，其中2000～250μm粒级有机碳对土地利用变化的响应更为敏感。

Effects of Land Use Change on Organic Carbon in Soil Aggregates

Objective ] The study aimed to determine the effects of land use change on organic carbon in soil aggregates. Method ] Using aggregate fractionation method, the change of organic carbon in soil aggregates from wetland soil to farmland soil was studied. Result] The mass ratio of 2 000 -250 μm size in soil aggregates was highest in two soils, and its value was 76.52%. The distribution pattern of organic carbon content in soil aggregates was 2 000 - 250 μm 〉 50 - 250 μm 〉 less than 50 μm. Land use change had a remarkable effect on organic carbon in soil aggregates and the influence in the aggregate of 2 000 - 250 μm was the most significant. The correlation between organic carbon in 2 000 -250 μm or less than 50μm size aggregate and soil organic carbon content reached a significant level, but not remarkable in 50 -250 μm aggregate. Conclusion ] The shift from wetland to farmland significantly changed the soil carbon pools, and organic carbon of the 2 000 -250 μm size in aggregates was more sensitive to land-use change.