Effects of grazing intensity on community characteristics and vegetation living states in alpine meadows

Changes in plant community characteristics and vegetation living states may reflect interspecific relationships and succession processes within plant communities. This study used the cold-season grazing grassland of the alpine meadow in Haibei, Qinghai Province as its research object to analyze and compare the characteristics of the vegetation community and the plant living state resulting from four different grazing management practices, including grazing prohibition (CK, no grazing), light grazing (LG, 4.5 sheep·ha⁻¹), moderate grazing (MG, 7.5 sheep·ha⁻¹), and heavy grazing (HG, 15 sheep·ha⁻¹). The results showed that 1) Gramineae, Cyperaceae, and weeds had the highest importance value indexes in LG, CK, and HG plots, respectively; 2) the Shannon-Wiener index, Simpson index, and Patrick richness showed an increasing trend with increasing grazing intensity; and 3) Elymus nutans and Poa orinosa had the highest survival status indexes in the LG plots, whereas Kobresia humilis and Saussurea nigrescens had the highest survival status indexes in the CK plots. Noteworthy, with the increase in grazing intensity, the survival status index of Saussurea nigrescens also increased. The results of this study showed that, as the grazing intensity increased, the community diversity of the alpine meadows and the survival status and dominant position of weeds in the community increased; in contrast, the survival status and dominant position of grasses in the community and the quality of the grassland decreased.