喀斯特地区坡耕地与退耕地土壤有机碳空间异质性及其影响因素  

Spatial variability of surface soil organic carbon and its influencing factors in cultivated slopes and abandoned lands in a Karst peak-cluster depression area

作　　者：吴敏[1,2,3] 刘淑娟[1,2,3] 叶莹莹[1,2] 张伟[1,2] 王克林[1,2] 陈洪松[1,2] 

机构地区：[1]中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,长沙410125 [2]中国科学院环江喀斯特生态系统观测研究站,环江547100 [3]中国科学院大学,北京100049

出　　处：《生态学报》2016年第6期1619-1627,共9页Acta Ecologica Sinica

基　　金：国家973计划项目课题(2015CB452703);中国科学院战略性先导科技专项子课题(XDA05070403);国家自然科学基金项目(31270555);中国科学院"西部之光"人才培养计划

摘　　要：利用网格采样(10 m×10 m),对比分析了典型喀斯特坡耕地(长期耕作)和退耕地(自然恢复)表层(0—15 cm)土壤有机碳(SOC)的空间变异特征,以期探究退耕恢复20a后SOC的空间异质性及其主要影响因素的变化。结果表明退耕地SOC含量(75.5 g/kg)显著高于坡耕地(15.1 g/kg),为坡耕地的5.0倍,说明自然恢复能显著提高SOC累积量;半变异函数分析结果表明退耕地基台值(521.7)为坡耕地(25.7)的14.9倍,说明退耕地SOC空间异质性远大于坡耕地。坡耕地和退耕地SOC的主要影响因子存在较大差异,土地覆盖类型、坡位、岩石出露率以及三者的交互作用显著控制着坡耕地SOC的空间格局,其贡献率分别为9.1%、6.3%、4.6%以及17.0%;土壤水分、坡度、岩石出露率以及三者的交互作用显著控制退耕地SOC的空间格局,其贡献率分别为26.0%、10.7%、7.2%以及3.6%;尽管岩石出露率对坡耕地和退耕地SOC的空间格局均有显著影响,但坡耕地SOC的主要控制因子为土地覆盖类型以及各因子的交互作用,而退耕地的主要控制因子为土壤水分。以上研究表明随着植被恢复和物种多样性增加,喀斯特坡地SOC的累积量和空间异质性增强,自然因素对SOC空间格局影响凸显,而岩石出露率始终控制SOC空间格局。Soil organic carbon（ SOC） content and its spatial heterogeneity are important components of regional and global carbon sequestration. However,the spatial variability of SOC in karst areas is poorly understood,especially in southwest China in areas of severe land degradation. In the present study,we selected isolated areas in the closest possible proximity to cultivated slopes in order to ensure similar soil and microclimate conditions. The spatial heterogeneity of cultivated slopes under long-term cultivation and abandoned lands under natural restoration in a karst peak-cluster depression area were analyzed by using the grid sampling method at 10 m × 10 m. A total of 230 soil samples were collected,including 123 from the cultivated slopes and 107 from abandoned lands. We used a one-way analysis of variance（ ANOVA） to evaluate the differences between the plots. The results showed that the average SOC content in the abandoned lands was ~ 5 times greater than that in the cultivated slopes,which indicates that vegetation recovery significantly improved the SOC content.The estimate of the spatial pattern and scaling of the studied SOC was performed by geostatistical analyses using semivariograms to determine the average variance between samples collected at increasing distances. The results showed that all semivariograms of the two plots were fitted to an exponential model. The sill values of the semivariogram functions for the abandoned lands were about 15 times greater those of the cultivated slopes,which indicates that the spatial variation of SOC in the abandoned lands was higher than that in the cultivated slopes. Stepwise regression and redundancy analysis showed that factors influencing the spatial distributions of SOC in the cultivated slopes and abandoned lands were different. In particular,land cover type,slope position,rock ratio,and their interaction explained 9. 1%,6. 3%,4. 6%,and 17. 0%of the total variance of SOC in the cultivated slopes,respectively. Soil water content,slope gradient,rock rati

关 键 词：喀斯特 土壤有机碳 空间异质性 冗余分析 

分 类 号：S153.6[农业科学—土壤学]