干旱区生态环境知识资源中心

To quantify changes in soil properties caused by agroforestry management practice, the fractal dimension (D-m) of soil particle size distribution (PSD) and their relationships with soil bulk density, porosity, soil organic matter (SOM) and soil total nitrogen (TN) were investigated in five types of tree-cropping systems in Chongqing, southwestern China. The five tree-cropping systems included (1) Citrus sinensis (L.) Osbeck system (CO), (2) CO and Ipomoea batatas Lam system (CI), (3) CO and Arachishypogaea (L.) system (CA), (4) CO and Zea mays (L.) system (CZ), and (5) CO and Solanummelongena (L.) system (CS). The results showed that the D-m values ranged from 2.7318 to 2.8062 with an order CO > CS > CZ > CA > CI. The D-m was positively related to clay and silt contents, but negatively related to sand contents. A relatively closer relationship was found between D-m and soil bulk density, non-capillary porosity and soil TN than with capillary porosity, total porosity and SOM. Soil quality was more effectively improved under multiple-species systems than monoculture systems. Our study confirmed that D-m is a useful parameter able to describe and monitor changes of soil properties in agroforestry systems. The results provide scientific reference for evaluating effect of management practices in agroforestry systems and have important implications for sustainable management of tree-cropping systems.