Effects of grazing on vegetation diversity
The linear fitting analysis of the vegetation diversity index and grazing gradient in different sites showed that the diversity index of five sites in the dry season and four sites in the rainy season (except for SP) were inversely proportional to grazing intensity (Figure 2), indicating that vegetation diversity was generally lost in the dry season under grazing pressure. The slope of Pielou index is lower than that of Simpson and Shannon. In addition, the relationship between diversity and grazing pressure was different between sites and seasons (Figure 2). Among them, DL (DT=0.1 ℃, RT=4.69 ℃, DP=118.8 mm, RP=306.7 mm) in wet and cold climate had the lowest slope with the increase of grazing pressure in both dry and rainy seasons. SP (DT= 7.37 ℃, RT=11.01 ℃, DP=62.5 mm, RP=139.8 mm) belongs to the warm-dry climate type, and the relationship between vegetation diversity index and grazing intensity is obvious seasonality, which is inversely proportional in the dry season and directly proportional in the rainy season.