Responses of alpine meadow functional group composition and nutrient quality to grazing intensity

To explore the responses of alpine meadow to long-term grazing activities of yaks, the alpine meadow on the eastern margin of the Qinghai-Tibet Plateau was selected as the research object. The effects of different grazing intensities on plant community biomass, functional group composition changes and forage quality were investigated in alpine meadow, and the interaction between vegetation functional group composition changes and forage quality was discussed. The results showed that: 1) The plant community biomass under grazing prohibition treatment was the highest, but the biomass of plant community decreased with the increase in grazing intensity. 2) Species richness and diversity showed a single peak with the rise in grazing intensity. The community diversity index, species richness, and evenness index under moderate grazing were higher than those under light grazing and heavy grazing. 3) Plant crude protein and crude ash content increased as grazing intensity increased. 4) With the increase in grazing intensity, there was no significant change in the proportion of Leguminosae, Ranunculaceae, and Forbs, while the proportion of Gramineae decreased. The proportion of Gramineae and Cyperaceae varied in the opposite way. 5) There was a significant correlation between the composition of functional groups and forage nutrition. The crude protein content decreased with the decrease in the proportion of Gramineae. However, it was negatively correlated with the proportion of Leguminosae, Ranunculaceae, and Asteraceae. In summary, plant community characteristics and nutritional quality have changed to different degrees under different grazing intensities. Compared with grazing prohibition, light grazing had the most effectively promoted aboveground and underground biomass. Moderate grazing was conducive to improving community species diversity, maintaining grassland plant community stability, and promoting sustainable development of grassland ecosystems.