Soil invertebrate diversity supports ecosystem multifunctionality along elevation gradients

Background and Aims: Mountain ecosystems are highly vulnerable to global changes. Soil biodiversity is critical for maintaining ecosystem multifunctionality, yet the contribution of soil invertebrate diversity in supporting multifunctionality in mountain ecosystems is poorly understood. Methods: Here, we assessed the contribution of soil invertebrate diversity, including α-diversity (i.e., species richness) and β-diversity (i.e., community composition), in explaining multiple ecosystem functions (e.g., water regulation, soil carbon stocks, nutrient cycling, organic matter decomposition, and pathogen control) along two independent elevation gradients of the Tibetan Plateau and Shennongjia Mountain in China. Results: Our results showed that ecosystem multifunctionality gradually increased with increasing elevation. Significant linear relationships were observed between species richness and community composition of soil invertebrates and multifunctionality along the elevation gradients, with species richness explaining more variance in multifunctionality than community composition. Furthermore, the positive associations between soil invertebrate richness and ecosystem multifunctionality remained consistent and robust along the two elevation gradients after considering climate and soil environmental variables. Structural equation modeling further revealed that the relationships between soil invertebrate diversity and ecosystem multifunctionality were primarily linked to elevation-induced variations in soil properties such as C/N ratio and pH. Conclusion: Our work highlights that the variation in soil invertebrate diversity along elevation gradients plays a critical role in supporting the multifunctionality of mountain ecosystems.