1. College of Geography and Environment Science, Northwest Normal University Lanzhou China
2. Key Laboratory of Resource Environment and Sustainable Development of Oasis Northwest Normal University Lanzhou Gansu Province China
3. College of Pastoral Agriculture Science and Technology, Lanzhou University Lanzhou China
4. College of Grassland Agriculture, Northwest A & F University Yangling China
5. School of Water and Environment, Chang'an University Xi'an China