Abstract: Lakeshore wetlands are among the ecosystems most vulnerable to climatic aridity, where soil microorganisms and their interactions play a pivotal role in maintaining ecosystem functions. However, it remains unclear how climatic aridity alters the complexity and stability of microbial co-occurrence networks in these intrazonal habitats, thereby impacting ecosystem multifunctionality (EMF). Here, we investigated soil microbial co-occurrence networks at 54 lakeshore wetland sites spanning a ~2,400 km climatic aridity gradient (covering both arid and semiarid regions) across the Mongolian Plateau and evaluated their relationships with EMF. Our results showed that climatic aridity significantly enhanced network complexity in arid lakeshore wetlands, whereas community stability significantly declined with increasing aridity in semiarid regions. Notably, aridity markedly reduced fungal diversity and community stability. Overall, microbial community stability and network complexity were regulated by biodiversity and jointly sustained the EMF in lakeshore wetlands. Specifically, EMF in semiarid regions was regulated by community stability mediated through network complexity; conversely, in arid regions, our findings underscore the predominant role of soil fungal diversity and stability in maintaining EMF. Collectively, this study demonstrates that the complexity and stability of microbial networks in lakeshore wetlands are shaped by climatic aridity and play a crucial role in maintaining EMF. These findings provide novel insights into the unique mechanisms by which biotic networks sustain ecosystem multifunctionality in intrazonal wetlands and offer theoretical guidance for the restoration of ecosystem functions in degraded wetlands. SCRIPT

Key words: ecosystem multifunctionality, network complexity, community stability, biodiversity, lakeshore wetland