(1. Department of Earth Sciences, National Natural Science Foundation of China, Beijing 100085, China; 2.CollegeofLandScienceandT echnology ,ChinaAgriculturalUniversity ,Beijing100193,China; 3.CollegeofUrbanandEnvironmentalSciences,CentralChinaNormalUniversity ,W uhan 430079,China; 4.CollegeofGeographyandEnvironment,ShandongNormalUniversity ,Jinan250014,China; 5.CollegeofAppliedArtsandScience,BeijingUnionUniversity ,Beijing100191,China; 6.InstituteofT ibetan PlateauResearch,CAS,Beijing100101,China;7.DepartmentofGeography andSpatialInformationT echniques, NingboUniversity ,Ningbo31521 1,Zhejiang,China; 8.SchoolofEnvironmentalandGeographicalSciences,ShanghaiNormalUniversity , Shanghai200234,China;9.NortheastInstituteofGeographyandAgroecology , CAS,Changchun130102,China)