Sa Xiao

Understanding the macroecological drivers of biodiversity and ecosystem stability, i.e. the ability of an ecosystem to maintain its structure and function, is crucial to inform how ecosystems can be managed and conserved effectively. Here, we conducted a field survey of plant and soil biota (bacteria, fungi, and nematodes) and estimated the temporal stability of aboveground productivity (ecosystem stability, proxied by normalized difference vegetation index [NDVI]) in 378 plots along an aridity gradient at a 1200 × 1200 km area in the Qinghai‐Tibetan Plateau. We found that ecosystem stability first increased then decreased with thresholds at aridity 0.24 along the spatial gradient. Plant diversity was positively related to ecosystem stability across the aridity gradient, whereas soil biodiversity, particularly fungi, was positively associated with ecosystem stability only under more water‐limited conditions (aridity > 0.2). Mechanisms for maintaining ecosystem stability shifted from plant community to soil fungal community with thresholds at aridity 0.2 along the aridity gradient. Our results underscore that plant and soil biota should be particularly maintained for ecosystem stability under less and more water‐limited conditions, respectively.

Summary: Trait‐based ecology provides a mechanistic framework for predicting how species and trophic interactions respond to environmental change, yet cross‐trophic trait linkages remain poorly understood. We investigated how the expansion of poisonous plants reshapes functional traits of plants, soil microbes, and soil fauna along climatic gradients on the Qinghai–Tibet Plateau, and how these shifts affect multitrophic trait networks and ecosystem complexity. To address this, we quantified 36 functional traits covering plants, bacteria, fungi, nematodes, and mites from 150 plots at 15 sites spanning a large climatic gradient. We found that poisonous plants induced coordinated shifts in trait values toward an acquisitive strategy in plants (thinner and softer leaves) and microbes (faster C and N cycling), but toward a conservative strategy in soil fauna (larger body size). Temperature weakened the poisonous plant–induced shift of plant trait values toward acquisitive strategies, whereas precipitation amplified the poisonous plant–induced shift of soil fauna trait values toward conservative strategies. Network analyses revealed that poisonous plants diminished connectivity and complexity among plant–microbe–fauna trait modules. By integrating trait‐based and network approaches across plants, microbes, and soil fauna, our study provides the first empirical evidence that poisonous plants can generate cross‐trophic trait mismatches and weaken the connectivity of plant–microbe–fauna trait networks across temperature and precipitation gradients. These findings advance trait‐based ecology by showing how poisonous plants can reorganize above‐ and belowground functional relationships, with implications for understanding biodiversity change in alpine grasslands.

Invasive plant species present a growing ecological and economic challenge, and often adapt rapidly to their novel environments through complex demographic and evolutionary processes. Invasion genomics offers powerful tools to disentangle these processes, but most studies rely on geographically narrow sampling across native and non‐native ranges. Erigeron canadensis is a cosmopolitan weed native to North America that has successfully invaded diverse climates worldwide. We used double‐digest restriction site‐associated DNA sequencing (ddRADseq) to investigate the genetic diversity and structure of 280 E. canadensis populations across the Northern Hemisphere. We found that native and non‐native populations maintained comparable genetic diversity. Population structure analyses revealed four genetic clusters that were mainly differentiated along latitudinal and aridity gradients. However, one cluster was strongly overrepresented in the non‐native compared to the native range. In the native range, genetic differentiation was shaped by spatial and environmental gradients, while in non‐native regions human‐mediated dispersal and repeated introductions disrupted environmentally driven genetic structure. Migration network analyses revealed limited intercontinental connectivity and a possible role of long‐distance dispersal in within‐range expansions. Genomic offset analyses showed that genotype‐environment mismatches in non‐native populations associated with reduced growth and reproduction. Together, our results indicate that the invasion dynamics of E. canadensis were driven by multiple introductions, population admixture, and lineage sorting, while some genotypes contributed disproportionately to the spread of this invader. The presence of apparent maladaptation suggests that even long‐established invaders may still be evolving in response to their novel environment, raising concerns about potential future expansions.

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.

Aim: Woody plant encroachment is reshaping grassland ecosystem functions worldwide. While its aboveground impacts are well documented, how this process alters microbial communities—key drivers of belowground processes—remains poorly understood. We aimed to (1) quantify the general effects of global woody plant encroachment on soil microbial community attributes in grasslands and (2) identify the abiotic and biotic factors driving these changes. Location: Global grassland ecosystems. Time Period: 2000–2024. Major Taxa Studied: Soil microbial communities (bacteria, fungi). Methods: We conducted a meta‐analysis of 241 paired observations to evaluate changes in microbial composition, diversity, biomass, activity and enzyme activity under woody plant encroachment. Results: Woody plant encroachment significantly altered soil properties. Woody plant encroachment also promoted a comprehensive increase in microbial community diversity, biomass, microbial activity and enzyme activity, as well as changes in community composition. The nitrogen‐fixing status of the encroaching species (biotic factor) significantly affected microbial responses: encroachment by nitrogen‐fixing plants resulted in a higher abundance of Bacteroidetes, fungal richness, microbial biomass phosphorus and phosphatase activity compared to non‐nitrogen‐fixing plants. In addition, abiotic factors, such as mean annual temperature, soil organic carbon and total nitrogen were identified as key factors driving microbial responses. Specifically, mean annual precipitation, mean annual temperature and elevation jointly regulated the effects of woody plant encroachment on soil microbial community attributes by influencing plant and soil properties. Main Conclusions: This meta‐analysis demonstrated that woody plant encroachment significantly reshaped soil microbial communities in grassland ecosystems. Our findings highlight the role of abiotic factors (climate, elevation, organic carbon and total nitrogen), and biotic factors (nitrogen‐fixing status) in mediating the response of soil microbial communities. These insights contribute to a better understanding of belowground ecological processes and provide valuable guidance for grassland management and predictions of biogeochemical cycles under global change.

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.

Global change drivers, such as shrub encroachment, alter above‐ and belowground communities, and the consequences of these changes for ecosystem functioning are largely unknown. We used the modified Price equation to quantify how the presence of shrubs alters the richness, composition, and abundance of plant and nematode communities and the resulting effects on ecosystem functioning (i.e., plant biomass and nematode carbon [C] metabolism) on the Qinghai‐Tibet Plateau. Plots with shrubs had increased plant biomass (mostly due to persisting plant species producing more biomass) and nematode C metabolism (mostly due to increases in nematode species richness). The strength of the species richness effect on plant biomass was positively associated with the strength of the species richness on nematode C metabolism. Increases in the biomass of persisting species and species gains promote plant biomass and nematode C metabolism, respectively, which may accelerate decomposition and C turnover on the Qinghai‐Tibet Plateau.

Global climate change is causing plants and other organisms to naturally expand their ranges to higher latitudes or altitudes. This expansion is leading to a strong reshuffling of biotic interactions with consequent ecosystem functions in the new ranges. We report here that soil fauna communities respond strongly to the cushion plants in a large‐scale latitudinal gradient in the Qinghai–Tibet Plateau. Local taxonomic, functional, and phylogenetic diversity of soil nematodes increased with the presence of cushion plants independently of the latitudinal gradient, but communities became more functionally similar in the presence of cushion plants and with increasing latitude. This functional homogenization was driven by deterministic processes through which the presence of cushion plants favored some functional traits (i.e., nematode trophic groups: herbivores and bacterivores). Our study reveals functional homogenizations of soil fauna communities in response to climate warming‐induced plant range expansion. Given that soil nematodes represent the most abundant and functionally diverse animal communities in terrestrial ecosystems, these findings indicate important changes in the functional dimension of biodiversity and in the delivery of ecosystem functions under climate change.