1. School of Ecology and Environment, Xinjiang University , Urumqi 830046, Xinjiang , China
2. Key Laboratory of Oasis Ecology, Ministry of Education , Urumqi 830046 , China
3. Xinjiang Jinghe Observation and Research Station of Temperate Desert Ecosystem, Ministry of Education , Jinghe 833300 , China
4. Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University , Nanning 530004 , China