1. Department of Urban and Environmental Science, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing 100871, China.
2. Ministry of Natural Resources, Ontario Forest Research Institute, 1235 Queen Street East, Sault Ste. Marie, ON, P6A 2E5, Canada, and Faculty of Forestry and The Forest Environment, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada.
3. Institute of Forest Ecology and Environment, Chinese Academy of Forestry, Beijing 100091, China.