1. Lanzhou University, College of Pastoral Agriculture Science and Technology, State Key Laboratory of Grassland Agro-ecosystems, Lanzhou 730020, China
2. Chinese Academy of Science, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou Gansu 730000, China
3. Lanzhou University, College of Pastoral Agriculture Science and Technology, State Key Laboratory of Grassland Agro-ecosystems, Lanzhou 730020, ChinacInstitute of Arid Meteorology, China Meteorological Administration, Lanzhou 730020, China