1. a State Key Laboratory of Resources and Environmental Information System , Institute of Geographical Sciences and Natural Resources Research , Chinese Academy of Sciences , A11, Datun Road, Anwai, 100101 Beijing, China
2. b Graduate School of the Chinese Academy of Sciences , A19, Yuquan Road, Shijingshan, 100039 Beijing, China
3. c Xinjiang Institute of Ecology and Geography , Chinese Academy of Sciences , No. 40, South Beijing Road, 830011 Urumqi, Xinjiang, China