1College of Life and Geography Sciences, Qinghai Normal University, Qinghai, Xining 810000, P.R. China
2Key Laboratory of Tibetan Plateau Environment and Resources (Ministry of Education), Xining 810008, P.R. China
3Chinese Academy of Engineering, Beijing 100088, P.R. China
4School of Environment, Beijing Normal University, Beijing 100875, P.R. China
Pol. J. Environ. Stud. 2014;23(6):2093–2102