Grazing affects plant community characteristics and the relationship between above-ground biomass and diversity, which has become a hot topic in grassland ecosystem research in recent years. The present study investigated grassland vegetation in the Two Rivers pastoral area based on 60 sampling points using sampling methods. The effects of grazing on the structural characteristics of plant communities were analysed using the α-diversity index, and the relationship between species diversity and the above-ground biomass of plant communities, as well as their changes, was explored. The results showed that grazing disturbance decreased the number of family species in the grassland plant communities and the similarity between communities; grazing activities significantly decreased the above-ground biomass of the grassland plant communities; the height and cover also showed a decreasing trend (p < 0.01), but the density of the grassland plant communities improved (p < 0.01). The Margalef index, the Shannon–Wiener index, and the Simpson index of the grassland plant communities all showed different degrees of decrease after grazing, while the Alatalo index showed an increase; biomass was positively correlated with the Margalef, Shannon–Wiener, and Alatalo indices and negatively correlated with the Simpson index (p < 0.01). Therefore, in the management and maintenance of grasslands, the impact of grazing on the structural characteristics of plant communities should be taken into account, and reasonable response policies should be implemented according to the actual local situation. This study provides a theoretical basis for grassland maintenance and management and the sustainable development of ecosystems in the pastoral areas of the two river sources of the Altay Mountains.

In order to explore the changes and interrelationships of grassland plant community species diversity and soil physicochemical properties with elevation gradient, this study takes the grassland in the Burzin forest area of Xinjiang as the research object and analyzes the responses of grassland species diversity, aboveground biomass, and soil physicochemical properties to the changes of elevation gradient within the altitude range of 1000~2200 m in this area. The results of the study show that: (1) The number of species and aboveground biomass reached the highest levels at elevation gradient III and showed a tendency of increasing and then decreasing with elevation. The Margalef and Shannon–Wiener indices were the largest at elevation III, while the Simpson and Alatalo indices were the largest at elevation I. (2) With the change of elevation, the available nitrogen (AN), available phosphorus (AP), soil electric conductivity (SEC), and soil pH showed a trend of increasing and then decreasing, while soil temperature decreased with elevation. Available potassium and soil water content reached their maximum values at elevation I and elevation IV, respectively. (3) The soil conductivity and diversity index were negatively correlated in elevation gradients I to III. In elevation gradient I~III, soil conductivity was positively correlated with the diversity index and aboveground biomass. Available nitrogen had a significant effect on plant diversity and biomass in elevation gradients IV to VI. (4) Aboveground biomass was significantly positively correlated with the Simpson’s index, while the relationship with the Shannon–Wiener index was less significant, and Margalef’s and Alatalo’s indices were not significant. Soil conductivity and pH significantly affected the Margalef and Simpson indices. Available nitrogen was closely related to the aboveground biomass and Margalef and Alatalo indices. Soil moisture content significantly affected Simpson’s index and the aboveground biomass. This study provides a solid theoretical foundation for the conservation and management of grassland plant community ecosystems along the elevation gradient, and has important reference value for study of the impact of environmental change on species diversity and biodiversity conservation.