Hanwen Cui

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.

Numerous studies have demonstrated that climate warming and the presence of shrubs affect herbaceous plant community composition and function. However, how the temporal stability of herbaceous plant community biomass responds to combinations of warming and the presence of shrubs remains largely unexplored. The effects and mechanisms of simulated warming and shrubs on the community stability were investigated in a 5‐year field experiment in alpine grasslands. Our results showed that warming alone or shrubs alone reduced community stability by decreasing species richness and temporal asynchrony. Additionally, warming alone or shrubs alone reduced community stability by decreasing community‐weighted means of leaf dry matter content of species. We also found that the interaction of warming and shrubs had a cumulative negative effect on plant community stability by increasing species synchrony. Synthesis. Our study suggests that continued global warming and shrub expansion may negatively affect the stability of natural grassland functions and services, and highlights the importance of temporal asynchrony and traits among species in moderating the effects of global change on ecosystem stability.

Dominant plants play crucial roles in supporting the functioning of terrestrial ecosystems. Plants can influence the spatial heterogeneity of environmental factors, as well as the spatial turnover in the composition of soil communities (i.e. β‐diversity of soil communities). However, we still poorly understand how dominant plants drive the spatial turnover in multiple ecosystem functions (β‐multifunctionality hereafter), and to which extent the effects of dominant plants are mediated by changes in environmental heterogeneity and the β‐diversity of soil communities. Antarctica supports one of the most challenging environments on the planet including low temperature and water availability. Here, we collected soil samples under three dominant plants (lichen, moss and vascular plants) and bare ground. We measured carbon storage, nutrient availability, nutrient decomposition, microbial biomass and pathogen control to calculate β‐multifunctionality. Both non‐vascular and vascular plants were associated with increased β‐multifunctionality compared to bare ground. We further showed that lichen mainly affected β‐multifunctionality through soil temperature heterogeneity and β‐bacterial diversity. Similarly, moss mainly affected β‐multifunctionality through the spatial heterogeneity of soil water content and β‐bacterial diversity. However, vascular plants did not significantly affect environmental heterogeneity. Instead, the responses of β‐multifunctionality to vascular plants were mainly driven by the β‐diversity of soil communities. These results indicate that environmental heterogeneity is important for turnover in multiple ecosystem functions in early successional stages (dominated by non‐vascular plants), while the importance of soil communities' heterogeneity becomes more significant in late successional stages (dominated by vascular plants). Synthesis. Our findings highlight the fundamental role of dominant plants in controlling the spatial turnover in ecosystem functions, and suggest that accelerated succession under current climate warming may increase bacterial β‐diversity but decrease abiotic heterogeneity, thereby leading to both increases (e.g. regarding functions related to microbial biomass) and decreases (e.g. regarding functions related to nutrient availability) in β‐multifunctionality and hence the spatial turnover in levels of ecosystem functioning.