FENG Yi-ming1,HE Ming-zhu3,XU Xiang-hong2,WANG Hui1(1.Forestry Department,Gansu Agricultural University,Lanzhou,Gansu 730070,2.College of Life Sciences and Technoligy,3.Shapotou Desert Experimental Research Station,Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Science,Gansu 730000)
