Department of Ecology;
College of Urban and Environmental Sciences;
and Key Laboratory for Earth Surface Processes of the Ministry of Education;
Peking University;
Beijing 100871 (China);
School of Urban and Environmental Sciences;
Northeast Normal University;
Changchun 130024 (China);
Institute of Biological Sciences;
University of Tsukuba;
Tsukuba;
Ibaraki 305-8572 (Japan);