Species niche and interspecific associations alter flora structure along a fertilization gradient in an alpine meadow of Tianshan Mountain, Xinjiang

The niche breadth, niche overlap, and interspecific associations of species in Bayinbuluke alpine meadow were investigated using ecology statistics to explore the competitive connection between the species and restricted resources in the community and the stable coexistence relationships among populations under different nitrogen addition gradients in the short term. The findings demonstrate the following. (1) The importance value of species shifted, with the fertilization samples Festuca ovina and Poa annua becoming the species with the highest importance value. Species richness fell gradually as fertilization gradient progressed, while the number of species grew initially and subsequently decreased. (2) Under different fertilization methods, the niche width and niche overlap values of the principal species changed. A positive link was found between niche width values and critical values under fertilization treatment compared with the controls. (3) By using the variance ratio approach, Pearson's correlation, and the association coefficient test, a positive correlation was discovered among species under low fertilization gradient treatment. However, a negative correlation was found under other gradients.