1. State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau; Northwest A&F University; Yangling Shaanxi 712100 China
2. Institute of Soil and Water Conservation; Chinese Academy of Sciences and Ministry of Water Resources; Yangling Shaanxi 712100 China
3. University of Chinese Academy of Sciences; Beijing 100049 China
4. Institute of Earth Environment; Chinese Academy of Sciences; Xi'an 710075 China
5. Kasuya Research Forest; Kyushu University; Fukuoka 811-2415 Japan
6. Arid Land Research Center; Tottori University; Tottori 680-0001 Japan