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以桂西北喀斯特原生林地、自然恢复地、放牧+火烧草地和玉米-红薯轮作地为对象,研究了不同人为干扰方式下4种生态系统中土壤团聚体含量及其有机碳的稳定性.结果表明:除玉米-红薯轮作地土壤的水稳性团聚体(>0.25 mm)含量为37.7%外,其余样地土壤水稳性团聚体(>0.25 mm)含量均大于70%;土壤团聚体结构破坏率为玉米-红薯轮作地(54.9%)>放牧+火烧草地(23.2%)>自然恢复地(9.8%)和原生林地(9.6%),差异显著.随培养时间的延长,团聚体有机碳的矿化速率先增加后减小,20 d后趋于平稳,而且随团聚体粒级的减小逐渐增大;相同粒级团聚体中有机碳的矿化速率为原生林地>放牧+火烧草地和自然恢复地>玉米-红薯轮作地;原生林地有机碳矿化率在1.7%～3.8%,显著高于自然恢复地、放牧火烧草地和玉米-红薯轮作地;有机碳的累积矿化量与矿化速率变化规律一致.土壤有机碳和团聚体中有机碳含量分别与矿化速率和累积矿化量呈极显著正相关,与矿化率极显著负相关.
The contents of soil aggregate and the stability of soil organic carbon in four kinds of ecosystems with different man-made disturbances were studied in the areas of native karst land, natural restoration, grazing + fire grassland and corn-sweet potato rotation in the northwest of Guangxi. The results showed that : The contents of soil water-stable aggregates (> 0.25 mm) were all more than 70% except for the water-stable aggregates (> 0.25 mm) of soil from sweet potato rotation field and 37.7% (54.9%), grazing + burning grassland (23.2%), natural recovery (9.8%) and primary forestland (9.6%), the difference was significant.As the incubation time prolonged, the organic carbon The mineralization rate firstly increased and then decreased, then stabilized after 20 days, and gradually decreased with the decrease of aggregate size. The mineralization rates of organic carbon in the same size fractions were primary forest land> grazing + fire grassland and Natural reclamation land> corn> sweet potato rotation>. The mineralization rate of organic carbon in native woodland was 1.7% ~ 3.8%, which was significantly higher than that of natural restoration, grazing and burning grassland and corn-sweet potato rotation. The cumulative mineralization of organic carbon and ore The rate of change is consistent with that of organic carbon and aggregates in soil Carbon content was significantly and positively correlated with mineralization rate and mineralization, respectively, and significantly negatively correlated with mineralization rate.