1. School of Geographical Science, Shanxi Normal University, Linfen, Shanxi Province, China
2. State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences (CAS), Urumqi, Xinjiang, China
3. Department of Geography, University of Kansas, Lawrence, KS, USA
4. Department of Geology, University of Kansas, Lawrence, KS, USA