1. CAS Key Laboratory of Forest Ecology and Management; Institute of Applied Ecology, Chinese Academy of Sciences; Shenyang 110164 China
2. University of Chinese Academy of Sciences; Beijing 100049 China
3. Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education; Guangxi Teachers Education University; No. 175 Mingxiu East Road Nanning 530001 China
4. Institute of Sand Fixation and Silviculture, Liaoning Province; Fuxin 123000 China
5. Daxinganling Academy of Forest Science of Inner Mongolia; Yakeshi 022150 China
6. USDA Forest Service, Pacific Northwest Research Station; Corvallis OR 97331 USA