WU Cheng-yong^{1, 2}, CAO Guang-chao², CHEN Ke-long², E Chong-yi^{1, 2}, MAO Ya-hui^{1, 2}, ZHAO Shuang-kai^{1, 2}, WANG Qi^{1, 2}, SU Xiao-yi^{1, 2}, WEI Ya-lan^{1, 2} 

¹ College of Geographical Sciences, Qinghai Normal University, Xining 810008, P.R.China
² Key Laboratory of Environment and Ecology of Qinghai-Tibet Plateau, Ministry of Education/Qinghai Key Laboratory of Natural Geography and Environmental Processes, Xining 810008, P.R.China