[1] Beijing Forest Univ, Key Lab Soil & Water Conservat & Combat, Beijing 100083, Peoples R China
[2] Water & Soil Conservat Inst Yanan City, Yanan 716000, Shaanxi, Peoples R China
[3] Univ Alabama, Dept Geog, Tuscaloosa, AL 35487 USA
[4] Beijing Forest Univ, Coll Environm Sci & Engn, Beijing 100083, Peoples R China
[5] China Agr Univ, Coll Resources & Environm Sci, Beijing 100094, Peoples R China