1. Forestry College, Inner Mongolia Agricultural University, Hohhot, China
2. Saihanwula National Forest Ecosystem Research Station, Chifeng, People’s Republic of China
3. Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Liupan Mountains Forest Ecosystems National Positioning Observation and Research Station, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, People’s Republic of China