中文摘要：

以贵州西南部喀斯特山区35年生和14年生花椒林为研究对象,并以未退耕旱地为对照,研究表层土壤（0-20 cm）水稳性团聚体分布及有机碳矿化特征,探讨土壤有机碳周转对不同花椒种植年限的响应。结果表明：随团聚体粒径的降低,两种年龄花椒林土壤水稳性团聚体含量呈现先增加后减少的倒＂V＂形分布,土壤水稳性团聚体分布主要出现在5-2、2-1和1-0.5 mm 3个粒级中;与旱地相比,花椒种植明显增加了全土和团聚体中有机碳和活性有机碳含量,并以14年生花椒林较高,而35年生花椒林存在较明显的衰减;随花椒种植年限的增加,土壤有机碳矿化累积量呈递减趋势,但土壤有机碳周转半衰期以14年生花椒林较长,显著高于旱地和35年生花椒林,表明14年生花椒林土壤有机碳更易累积,表现出较好的土壤碳固存能力;喀斯特山区种植花椒后,土壤有机碳存在＂汇-源＂的转换过程,因此花椒种植应注重长期维护管理,防止土壤质量的衰退。

英文摘要：

Taking two Chinese prickly ash orchards （35- and 14-year-old, respectively） in the karst mountain region of southwest Guizhou as test objects, and using the dryland as the control, we studied the changes of water-stable aggregates and organic carbon in surface soil （0-20 cm）, and discussed the response of soil organic carbon turnover to ages of Chinese prickly ash planta- tion. The contents of soil water-stable oggregates presented in an inverted ＇ V＇ -shaped distribu- tion with the decreasing soil aggregate size in two plantation ages, and the distribution of soil wa- ter-stable aggregates was dominant in 5 - 2, 2- 1, and 1 - 0.5 mm sizes. Compared with the dryland, organic carbon and readily oxidizable organic carbon in whole soil and different aggre- gates increased significantly in Chinese prickly ash plantations, being highest in the 14 years old Chinese prickly ash plantation, while an obvious decrease trend was found in the 35 years old plantation. With the increasing age of the plantations, cumulative mineralization of soil organic carbon decreased, but the soil organic carbon turnover was significantly longer in the 14 years old Chinese prickly ash plantation as compared with the dryland and the 35 years old Chinese prickly ash plantation, indicating that soil organic carbon was easier to accumulate in the 14 years old Chinese prickly ash plantation. After planting Chinese prickly ash in the karst region, the soil played a role of carbon sink at early stage, but transformed into carbon source thereafter. There- fore, we suggested that attention should be paid to long-term maintenance and management ofChinese prickly ash plantations to prevent soil quality decline in karst regions.