Figure 4 Non-metric multidimensional scaling (NMDS) plots depicting community turnover of different grazing gradients sites of dry season based on a Bray–Curtis similarity matrix of species abundance data.
The contour plots (Figure 5 and Figure 6) clearly show the local variation trend of diversity on the gradient of temperature, precipitation and grazing intensity. Vegetation diversity varied along the temperature and precipitation gradients, and the variation was greater along the precipitation gradients. The fluctuation characteristics of the contour lines showed that the variation range of vegetation diversity on the grazing gradient was greater than that on the temperature and precipitation gradients. In the dry season, vegetation diversity increased slightly with the increase of precipitation, while in the rainy season, vegetation diversity decreased first and then increased with the increase of precipitation.
In the rainy season, the vegetation diversity in DL, HL, EE and WA first decreased with the increase of grazing intensity, reached the lowest level at medium and low grazing intensity (1 or 2), then increased with the increase of grazing intensity, and reached the highest level at high grazing intensity (3), and finally the diversity index decreased again. In SP (DT=7.37 ℃, RT=11.01 ℃, DP=62.5 mm, RP=139.8 mm), vegetation diversity showed a significant increase with the increase of grazing intensity. During the rainy season, Pielou and Simpson indices were higher in high grazing intensity (3 and 4) than in medium grazing intensity (1 and 2), while Shannon index was also at a higher level, but significantly lower than Pielou and Simpson indices.