WU Bing1,ZHU Yuan-jun2,SHAO Ming-an3(1.College of Resources and Environment,Northwest A & F University,Yangling,Shaanxi 712100,2.State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,Institute of Soil and Water Conservation,3.Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101)
