Variation Characteristics of Plant Community Diversity and Above⁃Ground Biomass in Alpine Mountain along Altitude Grad in the Mangkang Mountain on Tibetan Plateau

Mountain ecosystems are the most biologically diverse areas on Earth, and many of their species play an important role in maintaining ecological balance. Protecting mountain ecosystems is conducive to the conservation of species diversity and the maintenance of ecological balance. In this paper, we take the vegetation communities at different altitude gradients in Mangkang Mountain area on the eastern edge of the Tibetan Plateau as the research object, and use the sample method to investigate the vegetation, and explore the relationship between species diversity and aboveground biomass of meadow and scrub communities in Mangkang Mountain and their changing patterns along the altitude gradient. The results showed that: (1) a total of 145 species of plants were found in the study area, belonging to 31 families and 68 genera, and the cover increased with the increase of elevation. (2) The pattern of change of plant species diversity along the altitudinal gradient was consistent, showing a "single peak" distribution pattern. The best fit curves of Shannon-wiener index, Simpson index, Margalef index, Pielou index and Shannon dominance index were all binomial and significantly correlated with each other (P<0.05). (3) The aboveground biomass of meadows was most fitted as a primary function with significant correlation with elevation (P < 0.05), the biomass of the scrub area was not significantly correlated with elevation (P > 0.05), and the species diversity was not significantly correlated with the biomass of the aboveground portion (P > 0.05). This study has important reference value for recognizing the distribution pattern of plant communities in Mangkang Mountain, as well as for future ecological protection and restoration.