Multifunctionality changes with plant functional groups in Antarctica

Plant functional group is increasingly recognized as vital for supporting multiple ecosystem functions simultaneously. However, variations in "ecosystem multifunctionality" relative to plant functional groups remain unclear, particularly in Antarctic terrestrial ecosystems. In particular, how plant presence relates to multifunctionality, whether this directly relates to their carbon inputs, or indirectly, via local changes in abiotic (soil moisture and pH), and biotic (soil biodiversity and their interactions) factors, is still an unresolved question. In this study, we collected soil samples from five areas in the Antarctic region, ranging from bare soil to areas dominated by nonvascular plants such as lichens, mosses, and vascular plants. We examined 12 ecosystem functions associated with carbon sequestration, nitrogen stock and cycling, soil organic matter (SOM) decomposition, microbial biomass and pathogen control to calculate ecosystem multifunctionality. Our results showed that ecosystem multifunctionality was higher in areas colonized by nonvascular plants and vascular plants compared to bare soil, which was concurrent with enhanced levels of carbon sequestration, SOM decomposition, and microbial biomass. Our structural equation model (SEM) showed that increased ecosystem multifunctionality beneath plants was associated with a higher number of microbial module hubs (indicative of stronger interdependence among microbial taxa) in nonvascular plants, but not in vascular plants. Analysis of SEM standardized contributions revealed the direct pathway as predominant in the connectivity pattern between vascular plant presence and ecosystem multifunctionality. Overall, these findings enhance our understanding of the differences in the pathways linking nonvascular plants, vascular plants, and ecosystem multifunctionality. It further highlights the necessity of incorporating microbial interactions to more effectively evaluate ecosystem multifunctionality, particularly in the context of Antarctic ecosystems.