2.1 Study area
The study was carried out in the Bayanbulak Grassland, which is the second largest grassland in China and is located in the Bayanbulak Basin of the Tianshan Mountains, Xinjiang Uygur Autonomous Region, northwest China. It covers an area of approximately 23 000 km2and contains around 36 plant species belonging to 26 genera and 16 families (Gong et al., 2010).