Ecosystem Multifunctionality in Semi-Arid Wetlands Is Jointly Driven by Soil Environmental Factors and Microorganisms

Biodiversity promotes ecosystem multifunctionality (EMF), yet it remains unclear how wetland types mediate the biodiversity-EMF relationship. This study investigated the differences in maintaining ecosystem functionality between lacustrine (lake) and riverine (river) wetlands in a semi-arid region. We examined how multiple soil environmental variables individually influence plant communities, soil enzyme activities, and microbial community composition and diversity, and we further explored how these factors drive EMF via interactions with microbial communities. Results showed that both individual ecosystem functions and EMF were significantly lower in lacustrine wetlands compared to riverine wetlands. Plant community attributes were the primary drivers of spatial heterogeneity in bacterial, fungal, and archaeal communities; conversely, soil enzyme activities were more strongly correlated with soil structure. Structural Equation Modeling (SEM) revealed distinct regulatory mechanisms: riverine wetlands were primarily subject to direct linkage between ecosystem multifunctionality and microbial diversity, whereas lacustrine wetlands exhibited a regulatory paradigm dominated by environmental filtering, where abiotic stressors (e.g., salinity and soil moisture) indirectly drove EMF by reshaping plant communities. These findings provide critical theoretical and technical insights for the conservation and restoration of wetland ecosystems.