Effects of grazing intensity and grazing season on plant species diversity in alpine meadow

For seven years, alpine meadow in an experiment in Haibei of Qinghai, China, has been lightly, moderately, or heavily grazed by cattle, or fenced off from grazing. Plant species richness and evenness showed different changes in summer and winter meadows. In summer meadow, species richness increased with grazing intensity, but species evenness reduced. In winter meadow, a hump model reflects the change in species richness that occurred with increase in grazing intensity, showing species richness was greatest at the moderate grazing intensity. Models of biodiversity change for the different meadows show that the summer meadow grazing intensity is too light.