1. College of Life Sciences, Anhui Normal University, Wuhu 241000, China
2. Key Laboratory of Regional Sustainable Development Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
3. Department of Environmental Science, University of Arizona, Tucson, AZ 85721, USA
4. School of Geography and Tourism, Anhui Normal University, Wuhu 241002, China