The relationship between diversity and stability and its maintenance mechanisms are important topics in current ecological research. In this study of Leymus chinensis grasslands in the Xilin River Basin, Inner Mongolia, analyzed the relationship between diversity and stability under the joint interactions of complex environmental factors (i.e., climate, topography, soil, and human activities) from the perspective of the community assembly, and the maintenance mechanisms of diversity and stability of the grassland ecosystem. We found that: (i) Functional diversity had the highest explanatory power for community stability, and the main path relationships among grazing factors, plant functional traits, functional diversity, and community stability revealed that niche differentiation and the response of species diversity to environmental conditions were the key mechanisms for maintaining the relationship between community diversity and stability in a grazing-induced degradation process. (ii) The differentiation of species diversity was mainly a consequence of environmental filtering, whereas the differentiation of functional group diversity was mainly caused by differences in community-weighted trait means. The differentiation of functional diversity mainly depended on the distribution pattern of plant functional traits, and higher functional diversity of the community was observed with increasing divergence in plant functional traits. (iii) The magnitude of community-weighted trait means was mainly determined by climatic factors, whereas the environmental filtering on plant functional traits was mainly a consequence of the effects of soil factors. An increase in the divergence of plant functional traits was correlated with an increase in grazing intensity. The convergence of plant functional traits was attributed to environmental filtering effects of climatic and topographic factors. (ⅳ) Species diversity increased with increasing grazing intensity and improvement in soil conditions. The diversity of functional groups mainly depended on climatic conditions, and the magnitude of functional diversity mainly depended on grazing intensity.

Excel spreadsheet contains these tabs:

- Table S1. Environmental parameters for 69 communities, including four climate, three topographic, nine soil, and one grazing intensity variables

- trait range

- stability components

- trait moments

- CWM

- diversity

- degradation gradient