1. Department of Forest Management, School of Forestry, Northeast Forestry University, Harbin, P.R. China
2. Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, Northeast Forestry University, Harbin, P.R. China
3. School of Geographic Sciences, Harbin Normal University, Harbin, P.R. China
4. Key Laboratory of Forest Plant Ecology, Ministry of Education Northeast Forestry University, Harbin, P.R. China
5. Faculty of Forest Science, Kim Il Sung University, Pyongyang, Democratic People’s Republic of Korea