Chang Guoliang 1, Zhao Wanqi 2, He Kangning 1, Shi Changqing 1
1.College of soil and Water Conservation,Beijing Forestry university, Key Laboratory of Soil and Water Conservation and Desertification Combating of MOE, 100083,Beijing; 2.Datong Forestry Tourism Bureau of Qinghai,810100,Datong, Qinghai:China