1. State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, China
2. School of Environment, The University of Auckland, Auckland 1010, New Zealand
3. State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining 810016, China
4. Department of Geosciences and Natural Resource Management (IGN), University of Copenhagen, 1350 Copenhagen, Denmark
5. Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
6. College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China