The general information of the sampled sites in the study area.

MAT and MAP in Table 1 are the abbreviations of mean annual temperature and mean annual precipitation, respectively (the same below). These climate data were the averages of observation data collected during a 30 year period (1987–2017). TMS, TTS and TD represent temperate meadow steppe, typical temperate steppe and temperate desert, respectively. The dominant soil types were from the “1:1,000,000 Soil Map of China in 2007”.