1. College of Urban and Environmental Sciences; Peking University; Yiheyuan Road 5 Beijing 100871 China
2. Research group of Plant and Vegetation Ecology (PLECO); Department of Biology; University of Antwerp; Universiteitsplein 1, Wilrijk Antwerp B-2610 Belgium
3. Institute of Tibetan Plateau Research; Chinese Academy of Sciences; Beijing 100085 China
4. Jet Propulsion Laboratory; California Institute of Technology; Pasadena CA USA
5. Institute of Botany; University of Basel; Schönbeinstrasse 6 Basel 4056 Switzerland
6. Laboratoire des Sciences du Climat et de l'Environnement; CEA CNRS UVSQ; Gif-sur-Yvette France