1. Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China
2. School of Ecology and Nature Conservation Beijing Forestry University Beijing China
3. University of Chinese Academy of Sciences Beijing China
4. Department of Ecology and Evolutionary Biology University of California Los Angeles California USA
5. Institute of Grassland Science Northeast Normal University, and Key Laboratory of Vegetation Ecology Ministry of Education Changchun China