1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China
2. University of the Chinese Academy of Sciences, Beijing 100049, China
3. Soil and Water Conservation Bureau of Shaanxi Province, Xian, Shaanxi 710004, China