中文摘要：

以贵州普定县陈家寨小流域为对象,探讨5种不同土地利用方式0-20 cm土层各活性有机碳组分的差异特征及其与土壤总有机碳间的关系。结果表明：贵州陈家寨喀斯特小流域0-20 cm土层土壤总有机碳含量为42.03（±25.08）g/kg,其中灌木林地有机碳含量最高为77.44（±28.38）g/kg,是耕地有机碳含量的3.5倍;土壤水溶性有机碳的含量表现为灌木林地〉荒草地〉人工林〉果园〉耕地,游离活性有机碳的含量表现为灌木林地〉人工林〉荒草地〉果园〉耕地,易氧化有机碳的含量表现为灌木林地〉人工林〉荒草地〉耕地〉果园;土壤总有机碳含量与各活性碳组分间均有显著相关关系,其中与游离活性有机碳的相关系数最高。不同土地利用方式下土壤有机碳含量不同,各活性有机碳组分既有相同之处,又存在差异,说明土壤活性有机碳的复杂性,因此不同活性有机碳的表征指标无论数值还是变化趋势不能直接比较。

英文摘要：

The differences of active organic carbon fractions in 0-20 cm soil layers and their relationships with soil total organic carbon （ SOC ） were studied in the karst small watershed of Chenjiazhai, Puding county, Guizhou province, under different land use patterns. The results showed that the average content of total organic carbon in 0-20 cm soil layer of Chenjiazhai karst watershed in Guizhou was 77.44（±28.38）g/kg. The organic carbon content of shrub land was the highest （ 77.44 - 28.38 g/kg ） , which was 3.5 times of that of cultivated land. The content of soil water-soluble organic carbon in descending order was as follows： bushes〉 grassland〉 plantation〉 orchard〉 arable land. The content of free active organic carbon in descending order was as follows： bushes〉 plantation〉 grassland〉 arable land〉 orchard. The content of easily oxidized organic carbon in descending order were as follows： bushes〉 plantation〉grassland〉arable land 〉 orchard. There was a significant correlation between total soil organic carbon （ SOC ） content and active carbon components, and the correlation coefficient between free organic carbon and freeorganic carbon was the highest. The content of soil organic carbon was different under different land use patterns, and the contents of active organic carbon were similar and different, which indicated the complexity of soil active organic carbon. Therefore, the characterization index of different active organic carbon can not be directly compared regardless of the value or the trend of change.