1. College
of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
2. Field
Ecology Department, International Crane Foundation, P.O. Box 447, Baraboo, Wisconsin 53913-0447, United States
3. Laboratoire
des Sciences du Climat et de l′Environnement, CEA-CNRS-UVSQ, CE Orme
des Merisiers, 91191 Gif sur Yvette Cedex, France