Niche differentiation is the underlying mechanism maintaining the relationship between community diversity and stability under grazing pressure

Abstract

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, we analyzed the relationship between diversity (species diversity, functional diversity, and functional group diversity) and stability (multidimensional stability defined by relationships between resistance, resilience, functional variability, and structural variability) under the joint interactions of complex environmental factors (climatic, topographical, soil, and grazing factors) from the perspective of the community assembly (community-weighted trait means, trait divergence, and trait convergence), 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 was mainly caused by grazing and the response of species diversity to environmental conditions were the key mechanisms for maintaining the relationship between diversity and stability. (ii) The differentiation of species diversity was mainly a consequence of environmental filtering which is due to soil factors, whereas the differentiation of functional group diversity was mainly caused by differences in community-weighted trait means which were determined by climatic factors. The differentiation of functional diversity mainly depended on the divergence of plant functional traits which mainly correlated with an increase in grazing intensity. The diversity of functional groups mainly depended on climatic conditions, and the magnitude of functional diversity mainly depended on grazing intensity. Our study is expected to enrich understanding of stability maintenance mechanisms in grassland ecosystems and provide guidance for grassland restoration and biodiversity conservation.