Impacts of plant and soil stoichiometry on species diversity in a desert ecosystem

Plant and soil stoichiometric ratios can be used to explain changes in the structural and functional characteristics of plant communities. Exploring the relationships between the stoichiometric ratios and plant diversity is helpful to further elucidate the effects of soil and nutrient constraints on community vegetation. However, such studies remain poorly understood in desert ecosystems. In this study, we analysed the effects of soil moisture and salt content on soil and leaf stoichiometry, species diversity and their relationships in the desert ecosystem of the Ebinur Lake basin. The results showed that: (i) Compared with the low soil moisture and salinity (SW2) environment, the soil and leaf C, N, P contents and soil stoichiometric ratios were larger in the high soil moisture and salinity (SW1) environment, and the leaf stoichiometric ratios were smaller. (ii) In SW1 environment, species diversity was negatively correlated with soil C:N and C:P, but weakly correlated with soil stoichiometric ratios in SW2 environment. In addition, the relationships between it and leaf stoichiometric ratios were reversed in different moisture and salinity environments. (iii) Structural equation modelling showed that leaf C:P, C:N and soil C:P had strong effects on species diversity. This research aims to provide a scientific reference for maintaining plant diversity, vegetation reconstruction and ecosystem restoration in desert areas, and enrich the ecological stoichiometric theory of desert ecosystems. Soil and plants in the desert ecosystem of the Ebinur Lake basin were mainly limited by N. The stoichiometric characteristics of the leaves and soil showed significant differences in the different moisture and salinity environments. The species diversity indices in high moisture and salinity were lower than those in a low moisture and salinity environment, which was related to soil salinity. The stoichiometric ratios of the leaf and soil were closely related to the species diversity, and the relationships between them were affected by soil moisture and salinity. Compared with soil, leaf stoichiometric ratios had a greater effect on species diversity.