1. Institute of Ecology College of Urban and Environmental Science, and Key Laboratory for Earth Surface Processes of the Ministry of Education Peking University Beijing China
2. Ministry of Education Key Laboratory of Ecology and Resources Use of the Mongolian Plateau School of Ecology and Environment Inner Mongolia University Hohhot China
3. Ecology and Biodiversity Group Department of Biology Utrecht University Utrecht The Netherlands
4. Department of Ecosystem Science and Management University of Wyoming Laramie WY USA