Effects of grazing and topography on α diversity and physical properties of the soil of alpine meadow communities in the Qinghai-Tibet Plateau

To explore the effects of grazing intensity and topography on the alpha diversity, soil’s physical properties, and the relationship between alpine meadow plant communities, three alpine meadow yak ranches in the northeastern Tibetan Plateau were selected. We were able to obtain results from our experiment, which are detailed as follows (1) Grazing intensity significantly impacted α diversity. The abundance index, Shannon–Wiener diversity index, dominance, and evenness were the highest during moderate grazing and were the lowest during heavy grazing, which were consistent with the " moderate disturbance hypothesis”. (2) The dominance and evenness of the shady slope reached the highest value during light grazing. (3) With the increase in grazing intensity, the soil’s bulk density increased and porosity and soil’s water content decreased, while the soil’s conductivity increased first and then decreased. (4) The porosity of the shady slope was higher than that of the sunny slope and the flat land; the soil’s water content, porosity, and conductivity of 0 – 10 cm layer were higher than that of the 10 – 20 cm layer, which was in contrast to the soil’s bulk density. (5) The correlation between soil’s physical properties and plant community’s diversity was significant in 0 – 10 cm soil layer; and soil’s bulk density was the closest. Topography and grazing intensity play an important role in the changes of the plant communities’ alpha diversity and soil’s physical properties in alpine meadow.