Soil microorganisms are central to litter decomposition, yet the functional role of phyllosphere microorganisms—the initial colonizers of senescing leaves—and their interaction with soil biota remain poorly understood. To disentangle their respective and combined contribution, we conducted a 12-month decomposition experiment with Pinus massoniana needle litter under three microbial treatments: NS (non-sterilized needles + non-sterilized soil), NSS (non-sterilized needles + sterilized soil), and SNS (sterilized needles + non-sterilized soil). The combined microbial community (NS) exhibited the highest decomposition rates, resulting in greater mass loss (~36%) and lignin loss (~33%) after 12 months than treatments containing either microbial source alone (NSS: ~26% mass loss, ~24% lignin loss; SNS: ~19% mass loss, ~17% lignin loss). This enhancement was attributable to functional complementarity between phyllopshere and soil microbial communities, expressed through stage-specific shifts in community composition and lignin degradation capacity. Co-occurrence network analysis further revealed treatment-specific microbial interaction patterns and highlighted key decomposer taxa, including Oidiodendron, Mycena, and Acidothermus. Microbial succession occurred throughout decomposition, while dominant decomposer-related phyla remained broadly consistent, with fungi largely dominated by Ascomycota (~84%) and bacteria mainly represented by Proteobacteria (~47%), Acidobacteria (~17%), Actinobacteria (~15%), and Firmicutes (~13%). Importantly, these shared taxonomic groups exhibited distinct temporal dynamics and interaction patterns across treatments. Overall, our results demonstrate that phyllosphere microorganisms actively contribute to litter decomposition and, through functional complementarity with soil biota, enhance decay process. These phyllosphere-soil microbiome interactions provide new mechanistic insights into microbial regulation of litter decomposition and nutrient cycling in forest ecosystems.

In sandy desert environments, plants experience substantial variation in growing conditions throughout the dune fixation process. Despite its ecological importance, the link between xerophytic plant trait adaptation and dune stabilization remains poorly understood. To address this gap, we evaluated 13 leaf functional traits related to physiological, structural, and biochemical properties in selected xerophytic species across four dune stabilization stages in northwest China, namely semi-fixed dunes (D1; vegetation cover, 23%), fixed dunes (D2; 32%), biocrusted-fixed dunes (D3; 46%), and herbaceous-plant-fixed dunes (D4; 60%). We applied leaf trait network (LTN) analysis to explore complex trait interrelationships and assess changes in network parameters during stabilization. Results revealed that both leaf traits and LTNs varied with stabilization stage. At the fixed dune stage (D2), xerophytes shifted from a resource-acquisitive strategy emphasizing rapid carbon and nutrient uptake to a more conservative strategy characterized by slower returns on investment. Leaf trait network connectivity increased with stabilization, as indicated by decreasing average path length and increasing edge density. Connectivity was positively correlated with soil bulk density (BD) and negatively correlated with soil volumetric water content, suggesting that increasing BD and water stress drove plants to adopt broader trait combinations, enhancing stress tolerance and physiological plasticity during dune stabilization.

Anthropogenic habitat fragmentation is a major driver of biodiversity loss in terrestrial ecosystems. However, its effects on species interaction networks remain poorly understood, especially for soil microbial communities. Using 23 grassland fragments within an agricultural mosaic of the agropastoral ecotone of northern China, we investigated the cascading effects of habitat fragmentation on soil microbial networks mediated by biodiversity. We found that habitat fragmentation negatively influenced soil microbial diversity and networks primarily by reducing patch area. Larger patches supported higher species richness and more complex and stable networks of soil bacteria and fungi. Habitat fragmentation induced reduced patch area had no direct effect on network complexity and stability, but indirectly decreased network complexity and stability by decreasing the species richness of soil bacteria and fungi. Our findings demonstrate that habitat fragmentation not only declines soil microbial biodiversity but also simplifies and destabilizes soil microbial networks in the agropastoral ecotone of northern China. We suggest that examining soil microbial network patterns in remnant habitats can provide valuable insights into the ecological consequences of habitat fragmentation beyond biodiversity loss.

Though livestock grazing is the most common grassland management, its effects on species interactions and spatial patterns of soil microbial communities are still under-investigated. By using the nested sampling strategy, we investigated soil prokaryotic and fungal communities in alpine steppes being either grazed or fenced on the Qinghai-Tibet Plateau (QTP), focusing on their species interactions indicated by the co-occurrence network and spatial patterns based on changes in network node numbers along the increasing sampling area. Our results showed that grazing consistently enhanced the network complexity of the soil prokaryotic community in different sites, possibly because grazing enhanced environmental heterogeneity and resource pulses while restricting microbial dispersal through physical disturbances. In contrast, grazing inconsistently influenced the fungal network complexity, likely due to the deterministic, dominantly assembled fungal community and heterogeneous grazing effects on environmental properties in different sites. Different from the spatial pattern for the community richness, the richness for interacted or co-occurred species tended to increase along the sampling area before 64 m² for fungi and 256 m² for prokaryotes, respectively, but then decreased after these tipping points, no matter with grazing or fencing. These results demonstrate that the grazing effects on microbial network complexity depend on community assembly mechanisms, and changes in the network node number along the sampling area presented a reverse U shape spatially. These findings provide novel clues for a comprehensive understanding of grazing consequences in alpine grasslands.

Plant phenology plays a fundamental role in ecosystem functioning by regulating species interactions and biogeochemical cycles. While both climatic factors and internal phenological linkages influence plant life-history events, their relative contributions remain unclear, particularly in species-rich subtropical forests. Using 6 years of monthly litterfall data (leaves, flowers and fruits/seeds) from a subtropical evergreen broad-leaved forest, we combined cross-correlation analyses with generalized additive models (GAMs) into a unified framework to disentangle internal linkages among multiple phenological events and nonlinear climatic effects. We reveal three key findings. First, we identified distinct climatic drivers for each phenophase: temperature and wind speed primarily controlled leaf fall, day length regulated flowering and the El Niño-Southern Oscillation (ENSO) strongly influenced seed production. Second, internal phenological linkages exerted equally strong or stronger effects than climate, with flower production driving leaf abscission, photoperiod triggering flowering and both floral initiation and resource remobilization released from leaf abscission jointly determining seed production. Most notably, we discovered cross-year reproductive trade-offs mediated by resource allocation constraints, where current high seed output suppressed flowering in the following year. Our results demonstrate that community-level phenology emerges from the interplay between phenophase-specific climatic responses and endogenous physiological linkages across phenophases. These findings challenge climate-centric phenological models and highlight the need to integrate internal plant resource dynamics when forecasting ecosystem responses to environmental change.

Arbuscular mycorrhizal fungi (AMF) can facilitate plant invasions, particularly in nutrient-depleted soils. Establishment of this mutualism often depends on both soil nutrients and secondary chemicals released by plants. Yet, it remains unclear how invasive plants maintain or enhance AMF colonization in nutrient-deficient soil. We investigated the effects of different levels of nitrogen (N: 0, 2 or 10 ppm) and phosphorus (P: 0, 6 or 25 ppm) added to sand in a factorial design on three flavonoids (isoquercitrin, quercitrin, quercetin) associated with AMF colonization in root exudates of Triadica sebifera from introduced and native populations. We assessed effects of soil nutrients alone on secondary chemical metabolism with sterilized growth substrate treatments. We found that plants from introduced populations had higher root exudate concentrations of quercitrin and quercetin plus greater AMF colonization than those from native populations under every N and P treatment combination. The effects of P availability on flavonoids depended on N availability. Flavonoid concentrations and AMF colonization decreased with P addition under no N treatment but increased with P addition under low N treatment. P addition had smaller effects on AMF colonization under the high N treatment. In sterilized growth substrate, P addition had stronger effects on quercitrin than quercetin. These results suggest that soil nutrients may influence AMF colonization by modifying flavonoids in root exudates. Our findings provide evidence that the responses of flavonoid metabolism to soil nutrients are an important driver of AMF colonization and the ability of invasive plants to sustain performance under nutrient stress.

Human activities have intensified global nitrogen deposition, profoundly affecting plant community structure and ecological functions. Phragmites australis, a key wetland species, is widely distributed and ecologically important; however, the mechanisms underlying its long-term response to nitrogen deposition, and whether nitrogen-induced parental effect can be stably transmitted to offspring remain unclear. To address this, we conducted a greenhouse experiment involving 12 genotypes of P. australis to investigate the effects of simulated nitrogen deposition on parental phenotypes and transcriptomes, as well as the consequent effects on offspring growth. Our results indicated that parental simulated nitrogen deposition enhanced the adaptability of parental plants to high-nitrogen environments by modulating metabolic pathways and promoting increases in leaf area and biomass in most genotypes. The legacy effect (parental simulated nitrogen deposition only) and cumulative effect (continuous simulated nitrogen deposition) had only minor impact on offspring performance, with responses exhibiting genotype-specificity; only a few genotypes showed significant growth or reproductive advantages following parental simulated nitrogen deposition. These findings suggest that parental effect associated with nitrogen responses are difficult to transmit consistently to offspring at the population level. Consequently, under nitrogen deposition, the overall growth and clonal propagation of P. australis populations are unlikely to be significantly enhanced.

Forest recovery is a critical nature-based solution for mitigating climate change, yet the microbial mechanisms governing soil microbial carbon use efficiency (CUE) remain poorly understood in geochemically active landscapes. Here, we conducted a large-scale paired-site study across a ∼1200 km transect in the subtropical karst region of southwest China, comparing 23 pairs of maize croplands and naturally regenerated secondary forests. Forest recovery significantly increased soil organic carbon (SOC) stocks but suppressed microbial CUE by 18.8%. This reduction in CUE was coupled with a substantial decline in microbial specific growth rate, while specific respiration showed no significant change. Structural equation modeling revealed that forest recovery suppressed microbial metabolic activity through three convergent pathways: (i) enhanced physical protection by exchangeable calcium/magnesium and carbonates, which restricted substrate accessibility; (ii) a fundamental shift in microbial community structure from copiotrophic to oligotrophic dominance, characterized by lower rrn operon copy numbers and (iii) reduced phosphorus availability. These findings suggest that in lithologically constrained ecosystems, the enhanced mineral preservation of organic matter, acting in concert with increased plant carbon inputs, may outweigh the impact of microbial residue production efficiency in regulating SOC accumulation. This study highlights that the relationship between microbial CUE and SOC accumulation is highly context-dependent following forest recovery and emphasizes that Earth system models should integrate these geochemical-biotic feedbacks to accurately predict the carbon sink potential of karst restoration projects.

Seed mass is a key trait influencing plant form and function. It reflects parental resource investment and influences seedling growth as well as the construction of root and leaf organs. However, how seed mass regulates root and leaf functional traits in legume species remains unclear. In this study, we selected 16 common herbaceous legume species growing in pots. The results showed that seed mass exhibited a U-shaped quadratic relationship with both fine root diameter and fine root biomass. Seed mass was significantly positively correlated with single leaf area, specific leaf area and stomatal length. However, it showed no significant correlation with leaf nitrogen concentration, leaf vein traits or stomatal density. Meanwhile, the relationships between seed and root traits and between seed and leaf traits in these legume species were markedly different from those reported for global non-nitrogen-fixing plants. These results indicate that seed mass may selectively regulate certain root and leaf traits. These findings provide a new perspective for understanding the formation of life history strategies in legumes and their responses and adaptations to environmental change.

Precipitation legacy effects (PLEs) profoundly alter the recovery trajectories of semi-arid grasslands under global climate change, necessitating mechanistic quantification for accurate climate risk assessment in these vulnerable ecosystems. Based on a 7-year precipitation simulation experiment followed by an in situ natural recovery study in a semi-arid sandy grassland in Inner Mongolia, China, we characterized PLEs across multiple ecological hierarchies and varying precipitation patterns using data from the final treatment year and the first post-treatment year. Our results demonstrated that vegetation traits exhibited stronger PLEs than soil physicochemical properties. The magnitude of PLEs increased with higher functionalization (composition → productivity) and finer hierarchy (community → functional group), exceeding 50% when significant. Dry PLEs were generally stronger than wet PLEs; both exhibited bidirectional (positive/negative) performance, yet consistently showed an inverse relationship between vegetation traits and trait resilience. Mechanistically, PLEs of moderate wetting and extreme drying were primarily carried by vegetation-mediated information, whereas PLEs of moderate drying and spring drought legacies were mainly carried by soil-mediated material. Specifically, functional group composition served as the key information carrier: annuals primarily carried positive dry PLEs and negative wet PLEs, while perennials carried the opposite PLEs; and the prevalent negative PLEs in community-level productivity and species diversity were specifically attributed to perennial grasses expansion after drying and annual forbs expansion after wetting. Soil available nutrients acted as the key material carrier, promoting PLEs in annuals via synergistic physicochemical pathways. Overall, both dry and wet PLEs generally impeded the vegetation recovery of the sandy grassland ecosystem, despite positive effects on certain finer-hierarchy ecosystem traits. We conclude that ignoring PLEs may lead to a severe underestimation of climate change risks in semi-arid ecosystems, particularly regarding their most sensitive components.

Soil microbial necromass carbon (MNC), a critical component of soil organic carbon (SOC), plays a vital role in the formation and stabilization of SOC. Climate warming and increased atmospheric nitrogen (N) deposition are key factors influencing carbon sequestration in grassland ecosystems. However, the impacts of warming and N deposition, as well as their interactions, on soil MNC in arid grasslands remain poorly understood. In this study, we investigated soil MNC, including fungal necromass carbon (FNC) and bacterial necromass carbon (BNC), following a continuous 16-year manipulation of warming and N addition in a desert steppe in Inner Mongolia, China. We also analyzed these parameters in conjunction with soil microbial diversity, plant coverage and soil properties. The results showed that N addition significantly increased soil MNC and FNC, as well as fungal diversity while not affecting BNC or bacterial diversity. Warming did not significantly affect MNC (including both FNC and BNC) or soil microbial diversity and there was no interactive effect between warming and N addition. Soil MNC, FNC and BNC were found to be higher in the topsoil layer than in the subsoil layer, and FNC contributed more to SOC than BNC. Notably, the increase of soil MNC and FNC under N addition was mainly mediated by increased soil N content. This study clarifies the critical role of MNC in soil carbon storage and offers an empirically grounded basis for forecasting grassland carbon changes under future global change scenarios.

The role of local plant microbiome in affecting invasive plant growth remains unclear. We examined how aboveground and belowground microbes from 25 phylogenetically distinct local plants affect the growth and endophytic community assembly of the invasive Ageratina adenophora. Our results showed that both the plant phylogenetics and the microbial community composition of local plants shaped endophytic community assembly in A. adenophora seedlings. Phylogenetic and physicochemical factors of the local plants did not explain their effects on growth of A. adenophora. Instead, growth was affected by both the microbial sources associated with local plants and the endophytes selectively enriched by A. adenophora. Aboveground microbes promoted A. adenophora growth more strongly than belowground soil microbes. On average, A. adenophora seedlings inoculated with aboveground tissues harbored a greater relative abundance of beneficial microbes and a lower relative abundance of detrimental microbes compared to those receiving soil inoculation. These results highlight that the invasive A. adenophora can selectively recruit microbial communities from local plant microbiomes to enhance its growth.

Plant trait network (PTN) has been used to elucidate plant adaptations to environmental changes. Enhanced anthropogenic nitrogen (N) deposition has had marked impacts on grassland ecosystems. A decline in atmospheric N deposition has occurred in many regions across the globe in recent decades. However, no studies have evaluated whether and how PTNs are involved in resource-use strategies of the grassland community in response to disturbance of N input. We investigated the responses of architecture and hub traits within PTN of a grassland community to cessation of N addition for 5 years after consecutive N addition for 15 years in a temperate grassland of Inner Mongolia. We found that three functional modules (nutrient utilization, water maintenance and light acquisition) operated independently under N addition. However, a 3-fold reduction in PTN modularity was found in response to cessation of N input by enhancing the integration of water maintenance and light acquisition module. Moreover, traits associated with water maintenance were strongly coupled with the nutrient-utilization traits. Cessation of N addition shifted PTN hub traits from phosphorus (P)- to N-related traits by alleviating P limitation. The traits of key drivers for ecosystem functions remained the most sensitive and robust responders to changes in soil nutrients. These traits may function as ‘meta–traits’, and drive coordinated responses of other traits to environmental variation. We applied PTN for the first time to examine multi-trait structure and functional integration, and highlighted the necessity of integration of PTN with other analyses to understand how plants shift their strategies in adaptation to nutrient enrichment.

Drought stress significantly constrains plant growth and terrestrial ecosystem productivity by disrupting the synergistic interplay between carbon (C) assimilation and nitrogen (N) cycling. This review synthesized evidence for a multi-tiered “C-N dual limitation” feedback loop under drought conditions, driven by the following key mechanistic disruptions: (1) impaired photosynthetic C assimilation due to combined stomatal and non-stomatal limitations; (2) suppressed soil N mineralization and reduced root N uptake; (3) drought-driven shifts in microbial community structure that weaken organic N mobilization and mycorrhizal nutrient transport; and (4) a metabolic tradeoff in energy allocation, whereby Adenosine Triphosphate (ATP) and Nicotinamide Adenine Dinucleotide Phosphate Hydrogen (NADPH) are diverted from growth to antioxidant defense. To unravel the complexity of this C-N imbalance, we addressed three pivotal issues: (1) to dissect the interactive regulation of physiological, metabolic, and molecular processes that reinforce the feedback loop; (2) to contrast the C-N coordination strategies across C₃, C₄, and Crassulacean Acid Metabolism (CAM) plants, linking these differences to divergent drought resilience; (3) to evaluate pathways to mitigate this limitation, ranging from the targeting of key regulatory hubs such as TOR/SnRK1 and ABA-ROS signaling, to leveraging of rhizosphere microbial ecology, and to discuss their integration into predictive models. By integrating current insights, this review presents a coherent framework for understanding plant drought resistance and proposes actionable strategies for sustainable ecosystem management in a changing climate.