Plant functional traits offer a mechanistic framework for understanding how plant communities respond to environmental change and shape ecosystem functioning. However, despite rapid advances over the past decades, the role of functional traits in driving wetland ecosystem functioning remains less well understood than in terrestrial systems, thereby limiting effective wetland conservation and restoration. In this review, we synthesize existing evidence on how plant functional traits and functional diversity influence key wetland ecosystem functioning, such as productivity, carbon cycling and nutrient cycling. We find that functional traits are key regulators of ecosystem functioning; therefore, targeted restoration should prioritize species with specific traits. We also call for coordinated actions across local and landscape scales to manage potential trade-offs among restoration objectives and enhance ecosystem multifunctionality. Clarifying the roles of functional diversity and wetland-specific flooding-adaptive traits in driving ecosystem functioning is identified as an important focus for future work. Moreover, a deeper understanding of how functional traits and diversity regulate wetland ecosystem functioning requires more manipulative experiments. This review highlights the role of plant traits in mechanistically linking vegetation dynamics to ecosystem functioning in wetlands.

Anthropogenic global change profoundly affects terrestrial ecosystem structure and function, creating an urgent and persistent need to accurately predict future ecosystem states. Field-based manipulative experiments provide critical mechanistic insights into these impacts but are inherently limited in spatio-temporal scope. Conversely, process-based models can extrapolate to broader scales but often contain simplified or unrealistic mechanisms that lead to uncertain projections. Data-model integration has emerged as an essential approach to bridging this gap, testing model assumptions against empirical evidence and guiding experimental design via model-based hypotheses. This review synthesized progress in integrating manipulative experiments with process-based models across three key global change drivers: elevated CO₂, climate change (warming and altered rainfall) and nutrient manipulation. We demonstrated how this integration reduced key uncertainties in processes such as photosynthesis, carbon-nutrient coupling and soil biogeochemistry, whilst exposing persistent gaps in plant hydraulics, microbial dynamics and multifactorial stresses. These advances were most pronounced in representing CO₂ fertilization effects, including improved stomatal optimization theory, dynamic carbon allocation schemes and coupled carbon-nitrogen-phosphorus cycling. By contrast, its application to warming, rainfall change and multi-nutrient interactions remained underdeveloped. To catalyze future progress, we propose specific strategies to foster a more synergistic cycle of knowledge co-production. These include prioritizing the quantification of mechanism-specific data to develop dynamic model formulations, systematically using multi-site experimental networks to benchmark and refine model processes across scales, and strategically employing models to design targeted experiments. Ultimately, these strategies are indispensable for developing more realistic models and achieving predictive understanding of ecosystem responses to global change.

Livestock grazing can alter plant productivity and diversity through defoliation, trampling and excretion. To isolate effects of defoliation, researchers commonly employ clipping experiments, although these effects of defoliation can vary considerably depending on the intensity and duration of grazing, as well as the type of ecosystem. Here, we compiled data from 1006 pairs of observations across 96 studies to assess the impacts of simulated livestock defoliation on various measures of plant diversity (including evenness) and productivity in China’s grasslands. Overall, simulated livestock defoliation resulted in greater species richness and evenness, along with elevated aboveground net primary productivity (ANPP) and belowground biomass (BGB), but lower aboveground biomass (AGB). Moderate levels of defoliation produced a stronger positive response in diversity compared to light or heavy defoliation, similar to later-season defoliation. Such effects were absent in alpine meadows, which leading to a negative association between responses of diversity and elevation. AGB was reduced by defoliation in all contexts, while BGB increased more when defoliation was light, later in the season and with shorter experimental durations; these effects were stronger in drier areas. Simulated grazing’s effects on ANPP switched from positive to negative as intensity increased. Changes in diversity were positively correlated with changes in ANPP in response to defoliation. These findings highlight that the effects of defoliation are context-specific in China’s grasslands, with important implications for grassland management and conservation.

The increasing frequency of drought events and elevated nitrogen (N) deposition both affect plant carbon (C) utilization, but whether their individual and interactive effects promote, inhibit or have no effect on C uptake and allocation remains unclear. We conducted a meta-analysis using 1247 observations from 84 published articles to assess how N addition and drought jointly affected plant photosynthesis, biomass allocation and nonstructural carbohydrates (NSC) allocation. Our results showed that N addition overall increased plant net photosynthetic rate (Pn) and biomass accumulation but decreased whole plant total NSC storage. Conversely, drought overall decreased Pn and biomass accumulation while increased whole plant total NSC storage. N addition significantly increased aboveground biomass allocation, whereas drought significantly reduced leaf biomass (LB). Although N addition and drought did not have significant interaction on Pn, biomass allocation and NSC allocation in terrestrial plants, their interaction significantly increased the root biomass of evergreen broadleaf plants, the LB of deciduous broadleaf plants and the root-to-shoot ratio of annual herbs. In conclusion, N addition and drought had opposite effects on C uptake, biomass accumulation and NSC storage in terrestrial plants. The interaction of N addition and drought on biomass allocation was affected by plant functional types. This study enhances our understanding of plant C utilization strategies under multiple environmental changes.

Tropospheric ozone (O₃) is a major air pollutant that threatens wheat production. However, the mechanisms underlying cultivar-specific responses remain unclear, particularly how stomatal traits and leaf structural characteristics contribute to differences in O₃ sensitivity among cultivars. A field experiment was conducted using 13 winter wheat (Triticum aestivum L.) cultivars exposed to ambient (A-O₃) or elevated (E-O₃, 1.5 times A-O₃) O₃ treatment in a Free-Air O₃-Concentration Enrichment system (O₃-FACE). Elevated O₃ significantly increased stomatal density on both adaxial and abaxial leaf surfaces, with a stronger response on the adaxial side, indicating independent regulation between surfaces. At the anthesis stage, stomatal and pore width significantly increased under E-O₃, whereas their length was not affected. Elevated O₃ significantly reduced adaxial epidermal thickness, abaxial epidermal thickness, mesophyll tissue thickness, and total leaf thickness during grain filling, with significant O₃ × cultivar interactions for all traits except abaxial epidermal thickness. Cultivars were classified into sensitive, intermediate, and tolerant groups. Sensitive cultivars exhibited significant reductions in leaf structure, whereas tolerant cultivars largely maintained or even enhanced structural integrity. Overall, cultivar sensitivity to O₃ was not directly associated with stomatal traits but rather with the ability to preserve leaf anatomy. These findings suggest that maintaining flag leaf structure is critical for improving wheat resilience to rising O₃ levels.

Plant-microbe interactions are strongly influenced by global environmental change, but bacterial responses in diversity, assembly and cross-interface connectivity across multiple plant-soil interfaces remain poorly understood. Here, we investigated bacterial communitiated interface-specific responses in bacterial community structure, assembly processes and the contributions of different interfaces to leaf endophytic bacterial communities. We found that interface identity plays the dominant role in shaping bacterial phylogenetic α- and β-diversity, with soil communities exhibiting higher diversity than phyllosphere communities. Nitrogen addition significantly reduced phylogenetic α-diversity and resulted in a more stochastic phylogenetic structure in bulk soil, whereas warming enhanced phylogenetic clustering in rhizosphere soil. Notably, warming increased phylogenetic dispersion and β- diversity of leaf epiphytic bacteria but decreased β-diversity in rhizosphere soil, indicating contrasting above- and belowground responses. Community assembly across interfaces was dominated by homogeneous selection, with stochastic processes contributing in an interface-dependent manner. Leaf endophytic communities remained remarkably stable, suggesting strong host filtering. Microbial source tracking revealed that warming and N addition increased soil-derived contributions to leaf endophytes, with over 70% of the community originating from soil under global change treatments. Overall, our results demonstrate that long-term warming and N addition drive interface-specific bacterial assembly and enhance soil to leaf microbial connectivity, highlighting the importance of a multi-interface perspective in understanding microbial responses to global change.

Root exudates play a crucial role in the communication and interaction between plants and soil. However, the responses of carbon (C), nitrogen (N) and phosphorus (P) exudation rates and their stoichiometric ratios to multifunctional group species reseeding in severely degraded alpine meadows remain poorly understood. This study was conducted in a severely degraded alpine meadow and four species composition treatments were established: grass mixtures, grass + legume mixtures, grass + legume + sedge mixtures and grass + legume + forb mixtures. The results showed that among the four reseeding treatments, the grass + legume + sedge mixture exhibited the lowest root C exudate rate and total exudate capacity, while N and P exudation rates, as well as their total exudate capacities, did not differ significantly between treatments. The carbon-to-phosphorus (C:P) ratio of root exudate was lowest in the grass + legume + sedge mixture, while the carbon-to-nitrogen (C:N) and nitrogen-to-phosphorus (N:P) ratios showed no significant differences among the four reseeding treatments. Root C and P exudation rates, as well as the C:N and N:P ratios, were significantly correlated with plant diversity, aboveground biomass, total biomass, soil organic matter and electrical conductivity. Variation partitioning analysis showed that root C exudate rate was most strongly influenced by biomass, whereas N and P exudate rates were more strongly affected by plant diversity. These findings suggest that species reseeding patterns significantly influence root exudates and their stoichiometric characteristics and contribute to understand the trajectories of soil microbes and soil health under reseeding.

Nitrification is a crucial biogeochemical process that regulates soil inorganic nitrogen forms and triggers soil nitrogen losses. While the prevailing paradigm focuses on the role of functional microbial guilds that drive soil nitrification, a clear mechanistic link between tree species and soil nitrification remains to be established in forest ecosystems. With a common garden experiment, we examined the impacts of the leaf economics spectrum, tree phenology, and symbiotic fungal associations on soil nitrification across 12 subtropical tree species in January and September. Our results revealed that soil potential nitrification rates, ranging from -2.13 to 1.96 mg N kg^-1 d^-1, varied among different tree species. Liquidambar formosana exhibited the highest soil nitrification rate, while Lindera communis and Elaeocarpus decipiens had the lowest soil nitrification rates at both sampling times. Leaf traits were stronger predictors of soil nitrification than soil variables. In particular, acquisitive tree species characterized by greater specific leaf area and lower leaf dry matter content significantly promoted soil nitrification. Deciduous tree species exhibited significantly higher soil potential nitrification rates than those of evergreen tree species. Structural equation models showed that the leaf economics spectrum positively affected litter N content, which in turn increased soil ammonium availability and subsequently promoted ammonia-oxidizing archaeal abundance, ultimately facilitating soil nitrification. Taken together, our study demonstrates a leaf trait-based framework for linking tree species to ecological processes and emphasizes that the choice of tree species based on the leaf economics spectrum plays a vital role in predicting ecosystem functioning.

While mangrove restoration has a great potential for enhancing soil organic carbon (SOC) sequestration in coastal wetlands, microbial-mediated SOC decomposition introduces huge uncertainty to this process. Microbial carbon use efficiency (CUE) is a crucial trait for microorganisms controlling SOC turnover, but how mangrove restoration could affect microbial CUE remains unclear. Here, we investigated the effects of mangrove restoration on microbial CUE in a typical restored mangrove wetland and further explored its connection to microbial necromass carbon (MNC) content. Our results revealed mangrove restoration increased microbial CUE by 37.84%–56.76% due to an increase in organic carbon quality and a shift in microbial community structure from fast-growing r-strategist (bacteria-dominated including Proteobacteria and Bacteroidota) to slow-growing K-strategist (fungal taxa and bacterial phyla such as Actinobacteriota, Acidobacteriota, and Chloroflexi). Microbial CUE was also positively correlated with MNC, explaining 73% and 69% variations in fungal and bacterial necromass C, respectively. These findings indicate that mangrove restoration enhances SOC sequestration not only through increased plant-derived carbon input but also by elevating microbial CUE and promoting MNC accumulation. Although bacterial necromass carbon showed a higher percentage increase, fungal necromass constituted the dominant portion of the accrued microbial-derived carbon pool, underscoring the critical role of fungal communities in the formation of stable SOC. Our study highlights the significant role of microbial processes in promoting SOC accumulation during mangrove restoration. These results emphasize the importance of incorporating microbial processes into coastal wetland restoration strategies to maximize C sequestration.

In eastern North America, cucumber-root (Medeola virginiana) is a widely distributed perennial forest herb that has been used as an ecological indicator of white-tailed deer (Odocoileus virginiana) browsing due to its predictable responses to deer exclusion (i.e. increased height, abundance). However, cucumber-root is less likely to occupy sites with high concentrations of soil manganese (Mn), which may limit its utility as an indicator under limiting soil conditions. We examined responses of cucumber-root total counts and flowering abundance to deer exclusion, competitive release from surrounding vegetation, and soil application of dolomitic limestone to determine the relative effects of these treatments over 7 years (2014–2021). Prior to treatment, initial total and flowering abundance were best explained by soil extractable Mn concentration. Post-treatment, fencing best explained increases in total counts, but flowering abundance was most affected by soil extractable Mn and pH. Initial soil Mn concentrations determined the effectiveness of dolomitic limestone application; microplots with moderate to high soil Mn (>6 cmol_c kg^-1) had increased flowering with increased pH, while flowering decreased on microplots with initially low soil Mn concentrations (<6 cmol_c kg^-1). We suspect changes to soil chemistry from liming affected plant stress, but that stress was either alleviated or intensified depending on initial soil Mn concentrations. Herbivory is an important driver of plant abundance across our study area but flowering response, a critical component of plant demography, seems to be driven by soil Mn. Cucumber-root may have limited utility as an indicator because soil chemistry mediates flowering responses to deer exclusion.

Extreme drought events are projected to increase in frequency and severity, posing serious threats to the stability of forest ecosystems. Forest drought resilience—an essential indicator of ecosystem stability and carbon sequestration potential under climate change—remains poorly understood in terms of its spatial distribution and variation across plant functional types. Here, we assessed global patterns and underlying drivers of forest drought resilience across latitudinal gradients, plant functional types (angiosperms vs. gymnosperms), and taxonomic ranks, using generalized linear models that integrate 282 tree-ring chronologies with satellite environmental and biotic data. Results showed that high-latitude forests had significantly lower drought resilience than those in mid- and low-latitude regions, primarily due to the combined constraints of limited water availability and low temperature. Angiosperm-dominated forests exhibited higher drought resilience than gymnosperm-dominated forests, with the former mainly driven by nutrients and heat, but the latter more constrained by water availability and species diversity. Forest drought resilience also differed among specific taxonomic ranks. Notably, the angiosperm genus Quercus exhibited high drought resilience, while some gymnosperm genera, such as Tsuga and Juniperus, also demonstrated strong drought tolerance through distinct physiological and morphological adaptations. These findings reveal that forest drought resilience is jointly shaped by climatic constraints and biotic traits, with clear latitudinal and phylogenetic differences. Recognizing these patterns can inform region-specific forest management and conservation strategies aimed at enhancing ecosystem stability under intensifying climate change.

Climate change and intensified agricultural activities are altering hydrological regimes and nitrogen inputs in wetland ecosystems, yet the mechanisms by which dominant wetland plants coordinate their responses to water-nitrogen interactions across growth stages remain insufficiently understood. This study investigated the dominant species, Carex schmidtii, utilizing a controlled experiment with three water levels (low water level, LW; control water level, W0; high water level, HW) and three nitrogen additions levels (no nitrogen addition, N0; low nitrogen addition, N1; high nitrogen addition, N2). Results revealed that C. schmidtii displayed pronounced stage-dependent plasticity to water-nitrogen interactions. Water availability emerged as the key factor determining growth and resource allocation, whereas nitrogen effects were strongly modulated by water conditions. During the vegetative growth stage, water limitation suppressed plant growth regardless of nitrogen addition, Under no nitrogen addition, plant height in the low water level treatment decreased by 22.16% relative to the control water level, and this growth inhibition persisted even under high nitrogen inputs, indicating that nitrogen could not compensate for water deficiency. At low water level, water use efficiency (WUE) and nitrogen use efficiency (NUE) reached the highest values and displayed a positive correlation, indicating efficient resource utilization. During the reproductive growth stage, nitrogen played a stronger role in promoting structural development and maintaining functional stability. Nitrogen additions alleviated NUE reduction under low water, whereas high water induced an escape response marked by reduced WUE (−29.10%) and elevated NUE (+119%). These findings highlight contrasting coordination strategies across growth stages and provide new insight into the adaptive mechanisms of dominant wetland plants under shifting hydrological and nutrient regimes.

Atmospheric aerosols can influence plant growth and terrestrial carbon cycling by altering solar radiation regimes and microclimate conditions. However, accurately quantifying their net effects requires a better understanding of how aerosol-growth relationships are modulated by cloud cover conditions and plant traits, for which empirical evidence remains limited. To address this, we conducted a six-year field campaign to monitor PM_2.5 concentrations (as a proxy for aerosol loading), meteorological variables, and daily stem growth in two temperate tree species: aspen (Populus euramericana Neva.) and pine (Pinus tabuliformis Carr.). We systematically evaluated how aerosols affect tree growth and how these effects are regulated by cloud cover, tree size, and species. Our findings revealed that aerosols generally promoted the stem growth of aspen, primarily through their diffuse radiation fertilization effect and concomitant improvements in air humidity (i.e. lower vapor pressure deficit). This positive effect was highly dependent on sky conditions: growth increased linearly under clear skies but exhibited a saturating-to-declining trend under overcast skies. Additionally, tree size influenced aspen’s growth response to aerosols, with smaller trees showing a lower absolute enhancement in stem cross-sectional area but a greater relative stem growth rate under high aerosol conditions. In contrast to the fast-growing aspen, the slow-growing pine showed no significant stem growth response to aerosols. These field-based findings propose a mechanistic framework for studying aerosolecosystem interactions and provide empirical benchmarks essential for improving predictions of plant growth under realistic environmental conditions.

Drought strongly influences plant residue decomposition and forest carbon cycling, and these effects are mediated by tree species traits. Although angiosperm residues generally decompose faster than gymnosperm residues due to higher nutrient concentrations, it remains unclear whether drought effects differ consistently between tree species across different plant organs and how underlying traits drive these differences. Herein, we examined the decomposition of wood, fine roots and leaf litter from Pinus tabuliformis (gymnosperm) and Robinia pseudoacacia (angiosperm) under 0%, 40%, and 80% rainfall reduction on the Loess Plateau, China. Drought significantly decreased plant residue decomposition, with the magnitude of reduction varying with both drought intensity and tree species. Decomposition of all plant residues declined more under 80% rainfall reduction than under 40% rainfall reduction. Moreover, under 80% rainfall reduction, decomposition declined significantly more in R. pseudoacacia than in P. tabuliformis, whereas no significant difference was observed under 40% rainfall reduction. This is because R. pseudoacacia has lower carbon and lignin concentrations, lower Proteobacteria abundance, and higher phosphorus concentration and Actinobacteriota abundance, yielding greater moisture sensitivity of its residue decomposition. Furthermore, drought-induced reductions in decomposition were greater for wood and leaf litter than for fine roots. Variation partitioning analysis and structural equation modeling further demonstrated that interactions among residue moisture, traits, and microbes governed jointly decomposition. Our findings highlight that contrasting tree species traits underlie drought-induced reductions in residue decomposition in drylands, which have important implications for predicting dryland carbon fluxes under future climate change characterized by increasing drought intensity and forest mortality.

Symbiotic (SNF) and free-living (FLN) N₂ fixation are key bioavailable nitrogen (N) sources in agroecosystems; yet, their integrated response to intercropping remains inadequately understood. We conducted a field experiment with intercropped silage maize (Zea mays L.) and Chinese milk vetch (Astragalus sinicus L.), assessing the intercropping effects on N dynamics by examining SNF and FLN in conjunction with soil properties and the composition of rhizosphere microbial communities, thereby linking plant performance with belowground processes. Intercropping increased silage maize total dry matter yield by 14.36% but reduced the total amount of symbiotically fixed N (Ndfa). This reduction was due to the suppressed biomass and lower tissue N concentration of the intercropped Chinese milk vetch, while its fixation efficiency (%Ndfa) remained stable. Crucially, while the gross rate of soil FLN was unaltered, intercropping reprogrammed the partitioning of FLN-derived ¹⁵N in a species-specific manner: allocation to the microbial biomass N pool increased in the Chinese milk vetch rhizosphere (from 13.85% to 25.37%), whereas allocation to the plant-available nitrate (NO₃^–-N) pool increased in the silage maize rhizosphere (from 2.67% to 15.67%). Several dominant genera of diazotrophs (Sinorhizobium, Bradyrhizobium), other bacteria (Microvirga, Bacillus), and fungi (e.g. Fungi gen Incertae sedis) were positively correlated with the proportion of inorganic N derived from FLN. We conclude that short-term intercropping reduces total symbiotic N input but enhances system performance by species-specifically redirecting FLN-derived N, a process mediated by crop-specific rhizosphere microbiomes to optimize N bioavailability for the cereal crop.

Mycorrhizal symbioses are critical for plant population and community dynamics, yet their role in mediating plant geographic spread under increasing anthropogenic pressure remains poorly understood. Here, we compiled geographic distribution and mycorrhizal information for 8791 vascular plant species across China and investigated how plant mycorrhizal strategies interact with human footprint to shape the extent to which species fill their potential ranges across species and space. We found that anthropogenic activities significantly affected range filling of arbuscular mycorrhizal plants, disproportionately reducing range filling of narrowranged species while benefiting widespread species. Conversely, range filling of ectomycorrhizal plants was primarily associated with abiotic environments. Our results suggest that mycorrhizal symbioses play a critical role in mediating plant responses to anthropogenic pressures across broad geographic scales and highlight the need to integrate plant-mycorrhizal interactions to predict biodiversity shifts in a changing environment.

Ongoing human activities and climate change threaten global grasslands, where plant nutrients are essential for ecosystem stability. However, long-term assessments (1985–2022) of above- and below-ground nutrient tradeoffs remain limited. Here, we conducted a 37-year study along the precipitation gradient (267–441 mm) to investigate the dynamics and trade-offs of plant carbon (C), nitrogen (N) and phosphorus (P). Our study found that with increasing local precipitation, above-ground C, N and P contents increased, while below-ground C content declined. The long-term response of plant nutrients varied spatially; the drier north (267 mm) and central region (334 mm) showed increased above-ground C but decreased N and P over time, whereas the opposite pattern occurred in the wetter south (441 mm). Additionally, the trade-off values of plant C, N and P stocks increased with local precipitation, and temporal stability of the N and P trade-off values was lowest in the drier north. Finally, precipitation fluctuation, fertilizer input and per capita GDP were identified as the key drivers of plant above- and below-ground nutrient dynamics in the northern, central and southern regions, respectively. With increasing local precipitation, the effect of climate on trade-off values shifts from negative to positive, whereas the effect of human activities shifts from positive to negative. Our findings highlight that the long-term response of plant nutrients is regulated by local precipitation patterns, through which the precipitation gradient has reshaped plant nutrient regulation by shifting the dominant driver from climatic to human activities factors.

Forest disturbance and climate change have caused a growing abundance of lianas in tropical and many temperate forests, which imparts a sense of urgency to explore the factors that control liana community assembly. Here, we examined the changes in liana community structure and functional traits during secondary succession in a warm temperate oak forest, and then analyzed how these varied with forest structural and soil properties. Liana species showed lower stem density in the late stage (85 ind. ha^-1) than the earlier two stages (190 ind. ha^-1 and 230 ind. ha^-1, respectively). Liana diversity also decreased along the succession. Compared with the earlier successional stages, lianas in the late successional stage invested more in acquisitive stem (lower wood density) and root (lower root carbon content). The decreases in liana abundance and wood density were strongly related to the decreasing tree diversity and the increasing canopy cover, tree diameter and tree height, with weak relationships with soil properties. These results demonstrate that forest structure is the main driver of liana community structural and functional assembly during forest succession, and is likely to shape liana community mainly by filtering stem traits.

Accurate spatial distribution of vegetation types is fundamental to understanding ecosystem structure, biodiversity patterns and environmental responses. However, predicting the distribution of lower-level vegetation classification units such as alliances remains challenging due to limited and uneven sample availability, particularly for rare or narrow-niche communities. To address this issue, this study proposed the KnowSim method that integrates expert-defined ecological knowledge to evaluate environmental similarity between locations. Vegetation types were predicted by assigning each site the type of its most ecologically similar sample. The method was tested in two regions of the Tibetan Plateau (Bome and Zoige), which exhibit contrasting yet complementary climatic and topographic conditions, together representing the Plateau’s typical environmental settings. Results demonstrate that KnowSim consistently outperformed statistical methods (Random Forest, eXtreme Gradient Boosting, Support Vector Machine and Logistic Regression) in both accuracy and type diversity. The improvement was particularly evident for alliances with sparse samples, achieving up to 24.6% higher accuracy in Zoige for alliances with fewer than five training samples. Moreover, the predicted vegetation maps better aligned with ecological gradients and field observations, demonstrating both ecological interpretability and predictive robustness under sample-limited conditions.

Understanding how biotic interactions vary across environmental gradients is critical for explaining the patterns of species coexistence in forest communities. Recent studies indicate that mycorrhizal association and environmental factors, particularly rainfall, can shape variations in conspecific negative density dependence (CNDD), although long-term community level evidence from natural forests remains limited. Using 20-year seedling censuses from a species-rich tropical forest, we investigated how interannual rainfall variability and mycorrhizal type modulated CNDD and seedling survival. Our results showed that seedling survival was greater in the years with higher rainfall, which was largely regulated by the interactions between the conspecific and heterospecific neighbors. Notably, rainfall and conspecific density were the predominant drivers of seedling survival, showing that seedlings exhibited higher survival at low conspecific densities and positive or nonlinear responses to rainfall. Heterospecific neighbors also had positive effects on seedling survival, which may be influenced by habitat conditions. Moreover, CNDD was stronger in arbuscular mycorrhizal (AM) species than in ectomycorrhizal (ECM) species, particularly in wetter years. Our findings revealed that interannual rainfall interacted with species’ mycorrhizal strategies to shape demographic outcomes, underscoring the pivotal role of mycorrhizal types in determining seedling dynamics. Thus, our study highlights the importance of incorporating mycorrhizal types into the predictions of tropical forest biodiversity.

Arbuscular mycorrhizal (AM) fungi are well documented to alleviate physiological stress in plants. While AM fungal benefits under low-water conditions are well studied, AM fungal benefits under high-water conditions are far less understood. Previously, direct experimentation on AM fungal effects on plant performance has largely focused on agricultural crop species, frequently using categorical ambient and drought condition treatments rather than leveraging gradients appropriate for detecting non-linear responses. Thus, there is little understanding about how AM fungi may mediate native, terrestrial plant responses across gradients of water availability. Here, we tested the effects of AM fungi on a common, ruderal plants species (Solidago altissima) across a wide range of water availability in a greenhouse experiment. AM fungi improved plant performance at moderate and high levels of water availability, but surprisingly AM fungi did not improve plant performance in the lowest water availability treatment groups. Most importantly, without AM fungi, S. altissima was unable to take advantage of increasing water availability, indicating that even for a ruderal plant species, mycorrhizal associations may be a critical component to plastic responses in plant performance under climate-driven changes in water availability.

Genetically based trait covariances are critical for invasive plant adaptation. Clonal growth can facilitate local expansion; however, the evolutionary relationship between clonal timing and performance remains underexplored. Particularly, it is unclear how these traits covary to affect adaptation across latitudes. Here, we investigated variation and covariance in two clonal traits (the timing of the first ramet emergence and peak number of ramets within a growing season) of Spartina alterniflora, an aggressive coastal invader in China. We sampled eight populations spanning the entire latitudinal range of S. alterniflora along the Chinese coast (21° N–38° N). These seeds were cultivated in three common gardens at low (21° N), mid (28° N), and high (38° N) latitudes. Plants from low-latitude garden exhibited significantly earlier ramet emergence and greater ramet production than those in mid- and high-latitude gardens across the growing season, highlighting substantial phenotypic plasticity. The timing of the first ramet emergence showed a provenance-by-environment interaction, and was driven by abiotic factors at original sites. Furthermore, we found a generally negative covariance between ramet emergence time and ramet production, populations originating from low-latitudes consistently exhibited earlier ramet emergence with more ramets. Our findings suggest that clonal traits covariances were likely to benefit the local adaptation of S. alterniflora at low latitudes, and such covariances appeared to be driven by genetic admixture. Our study advances the understanding of how variable life-history strategies enable invasion success across environmental gradients in the introduced range, and highlights the need for region-specific management strategies tailored to local phenology.

Leaf nitrogen to phosphorus ratio (N:P) has widely been used to determine plant N and P limitations at community or larger scales. However, the underlying physiological mechanism of this rule of thumb has seldom been explored. Here, we quantify how leaf P fractions vary with leaf N:P and estimate the critical values and dynamics of leaf P fractions along the N:P gradient—from N limitation to P limitation, based on data collected from 143 unfertilized wild species in peer-reviewed literature. As leaf N:P increases, all P-fraction concentrations decline, with lipid P, inorganic P and residual P concentrations showing steeper declines than total P; the allocation-proportion ratios of metabolic P, nucleic acid P and lipid P shift from approximately ≤3:3:9 (corresponding to N:P ≤ 10), to 3:3:5 (N:P = 15) and to ≥3:3:3 (N:P ≥ 20). These findings suggest that most leaf P-fraction concentrations are more sensitive than total P to leaf N:P variations and reveal complicated P-use strategies of coordination (metabolic P and nucleic acid P) and trade-off (lipid P vs. metabolic P and nucleic acid P). This study provides a physiological explanation for using the leaf N:P ratio as a nutritional diagnosis and helps to better understand plant adaptive P-use strategies across diverse N and P availability conditions.

Phragmites australis is a dominant species in estuaries. It can reproduce sexually and clonally. Understanding the latitudinal patterns of the traits can help in predicting adaptive strategies across environmental gradients. However, changes in growth and reproductive traits of P. australis, as well as growth-reproduction relationships along latitudinal gradients remain unclear. We sampled P. australis from five estuaries along latitudinal gradients in China and analyzed changes in growth, reproductive, and biomass allocation. The results revealed that with increasing latitude, the ramet height, flowering frequency, inflorescence biomass per flowering ramet, and weight of 100 seeds increased, whereas the ramet density generally decreased. The latitudinal growth and reproduction patterns were primarily influenced by variations in the temperature, precipitation, and light intensity. These results suggest that high-latitude P. australis populations may reduce their flowering and seed production under climate warming.