沱江流域不同土地利用方式紫色土有机碳储量特征

沱江流域是长江上游四川境内的重要支流，紫色土为其主要的耕地资源。由于长期人口过载和不合理利用，流域内紫色土退化普遍严重。以四川盆地沱江流域紫色土为研究对象，按流域各区段分上中下游三层选样，研究不同土地利用方式下紫色土有机碳储量特征，为紫色土退化评估及地力维护提供参考。结果显示，不同土地利用方式紫色土壤有机碳总量以林地（13．876g／kg）显著高于果园地（9．655g／kg）、菜园地（9．261g／kg）、草坡地（7．968g／kg），以玉米地（6．134g／kg）最低。水溶性有机碳的含量呈现林地〉果园地〉菜园地〉草坡地〉玉米地趋势。同时，流域上、中、下游紫色土有机碳总量总体上差异显著，且以上游区段紫色土壤有机碳总量最高。流域中下游紫色土有机碳总量变化较大。其中，林地以下游高于中游，果园及草坡地以中游高于下游。而且，菜园地、玉米地在3个区段上差异未达显著水平。沱江流域紫色土有机碳储量总体特征表现上游最高，中下游变化复杂，下游略高于中游区域。

Soil Organic Carbon Storage of Purple Soil in Different Land Uses in Tuojiang River Valley, Sichuan

The Tuojiang River, running through Sichuan Basin as a key tributary to the Yangtze River, characterizes dominant in purple soil distributions. However, over-population and irrational land uses result in serious degradation of purple soil. So as to evaluate the tensity of degradation and scavenge for productivity improvement, this study focused on surveying the soil organic carbon storage and distribution within different land uses in the Tuojiang River basin. The results showed that significant differences can be analyzed among soil organic carbon contents of forestland, orchard, vegetable garden, maize field and grass slope, which were measured as 13. 876, 9. 655, 9,261, 6. 134 g/kg and 7. 968 g/kg, respectively. The dissolved organic soil carbon content also embodies the same changing trend. In different sections of the Tuojiang River basin, soil carbon content is significantly higher than those in the lower reaches, but complicate changes can be investigated between the middle and the lower reaches. A general tendency is that organic soil carbon content in the upper reaches is higher than those in the lower reaches, and that those in the middle reaches is the lowest in amount.