Effects of grazing intensity on community structure and the soil’s physical and chemical properties in an alpine meadow on the Eastern Qinghai-Tibet Plateau

In order to explore the effects of yak grazing disturbances on alpine meadows in different areas, we analyzed the aboveground biomass (AGB), belowground biomass (BGB), species richness (Richness), Shannon-Wiener index, Simpson index, Pielou index, 0–10 cm soil moisture (SM), and soil organic carbon (SOC) following grazing at different intensities (G₁, G₂, G₃ and G₁ < G₂ < G₃) in Maqu County (grazing intensity: G₁ = 13 sheep·ha^–1, G₂ = 17.6 sheep·ha^–1, G₃ = 32.5 sheep·ha^–1) in Gannan Prefecture, Gansu Province, and in Maqin County (grazing intensity: G₁ = 13.2 sheep·ha^–1, G₂ = 15 sheep·ha^–1, G₃ = 43.5 sheep·ha^–1) in Golog Prefecture, Qinghai Province. The results are as follows: 1) AGB showed a downward trend in both Gannan and Golog with increases in grazing intensity, and AGB in grazing areas was lower than that in no-grazing areas. AGB was significantly lower in Golog than in Gannan following G₃ treatment (P < 0.05). Under the same level of grazing intensity, BGB in Golog was distinctly lower than in Gannan (P < 0.05). 2) The species richness, Shannon-Wiener index and Pielou index of plant communities increased with increasing grazing intensity in the Gannan region. Following G₁ treatment, Richness, Shannon-Wiener index, Simpson index and Pielou index were significantly higher in Golog than in Gannan (P < 0.05). 3) In the no-grazing area, the AGB of high-quality pasture (grass and sedge) accounted for about 50% of aboveground biomass. With the increase in grazing intensity, the proportion of high-quality pasture was reduced, while the proportion of weeds (edible weeds and poisonous weeds) increased. 4) Following G₁ and G₂ treatments, soil organic carbon was significantly higher in Gannan than in Golog (P < 0.05). Long-term grazing disturbance significantly reduced soil moisture, and was significantly lower in Gannan than in Golog (P < 0.05). Regional differences have an impact on species diversity, soil organic carbon, and soil moisture. In summary, we conclude that grazing has a greater impact on the vegetation and soil of Gannan.