1. Institute of Natural Resources and Ecology, Heilongjiang Academy of Sciences, Harbin 150040, China
2. Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, CH-8903 Birmensdorf, Switzerland
3. Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China
4. School of Life Science, Hebei University, Baoding 071002, China
5. Heilongjiang Academy of Forestry, Harbin 150040, China