1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Water and Soil ConservationNorthwest A&F University Yangling Shaanxi 712100 PR China
2. Institute of Soil and Water ConservationChinese Academy of Sciences and Ministry of Water Resources Yangling Shaanxi 712100 PR China
3. Department of Soil and Water ConservationYangtze River Scientific Research Institute Wuhan Hubei 4300104 PR China