1. Key Laboratory of Alpine Ecology and Biodiversity; Institute of Tibetan Plateau Research; Chinese Academy of Sciences; 16 Lincui Road Chaoyang District Beijing 100101 China
2. CAS Center for Excellence in Tibetan Plateau Earth Sciences; 16 Lincui Road Chaoyang District Beijing 100101 China
3. College of Urban and Environmental Sciences; Peking University; Beijing 100871 China
4. Department of Biology; Centre of Excellence PLECO (Plant and Vegetation Ecology); University of Antwerp; Universiteitsplein 1 B-2610 Wilrijk Belgium