Effects of grazing intensity on plant community characteristics in mountain meadows in the middle section of the northern slope of the Tianshan Mountains

The study was to determine the effects of different grazing intensities on plant community species composition, importance values, community characteristics, and diversity of mountain meadow grasslands in the middle section of the northern slope of the Tianshan Mountains. Three kinds of grazing intensity were used, including no grazing (CK), light grazing (LG), and heavy grazing (HG). The results showed that the species composition was different under different grazing intensities. With increased grazing intensity, the importance value of high-quality gramineous plants and leguminous plants decreased, whereas that of Achnatherum inebrians and forbs increased. Margalef index, Shannon-Wiener index, Simpson index, and Pielou index for the plant community increased after an initial decrease but were the highest under the HG treatment. Plant community height, community coverage, community density, and aboveground and belowground biomass were significantly reduced (P < 0.05), and plant roots were primarily distributed in the 0–10 cm soil layer. Plant community richness, diversity, and community characteristics were negatively correlated. In conclusion, the increase in grazing intensity led to changes in species composition of plant communities in mountain meadows. The HG treatment increased the advantages of A. inebrians and forbs, and the plant community richness and diversity index were the highest; however, the height of the plant community was significantly reduced, as was density, coverage, and biomass.