1. College of Geographic Science, Hunan Normal University, Changsha 410081, China
2. Department of Biological Sciences, the University of Québec at Montreal, Montreal, QC H3C 3P8, Canada
3. Key Laboratory of Agro-ecological Processes in Subtropical Region, The Chinese Academy of Sciences, Changsha 410125, China
4. Dongting Lake Station for Wetland Ecosystem Research, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125, China