1. Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, P.O. Box 9717, Beijing 100101, China
2. USDA Forest Service, Oregon State University, Oregon 97333, USA
3. Department of Ecology and Evolutionary Biology, University of Kansas, KS 66045, USA
4. Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH 03824, USA
5. Institute of Forestry Ecology and Environment Protection, Chinese Academy of Forestry, Beijing 100091, China