Abstract:
Representative plant communities on the northern slope of the Usun Mountains, Xinjiang were selected for sampling and investigation. A total of 48 plots were established along the slope, ranging from 1,400 to 3,000m asl. The investigated vegetation communities covered all community types along the altitude gradient. Using TWINSPAN classification, GAM model diversity index fitting and comprehensive DCCA sorting analysis, the results showed that: (1) Plant genera and species were relatively diverse. Rosaceae, Cruciferae, Leguminosae, Compositae, Poaceae and Labiatae were relatively abundant, seed propagation was dominant. (2) Four vegetation vertical bands were classified from high to low elevation as sub-alpine meadow, coniferous forest, mountain steppe and desert steppe, respectively. (3) Total species richness, Simpson index, Shannon-Wiener diversity index and Pielou evenness index exhibited multiple peaks with the increase in elevation gradient, although only the last Pielou evenness index peak was very obvious. (4) The specific species diversity index pattern observed along the northern slope of the Usun Mountains was likely related to climate and soil nutrient status, and was specific for the Tianshan Mountains. (5) Under complex mountainous terrain, the differences in biotope conditions were very significant. The combination of elevation, slope, soil moisture, available phosphorus, available potassium and pH influenced and controlled the formation of community distribution patterns on the northern slope. This study revealed vegetation distribution patterns and their relationship with the environment on the northern slope of the Usun Mountains and provided important information for biodiversity conservation and the development.
