Plant community composition influences soil carbon (C) storage and stability in coastal wetlands, but such effects remain unclear in the non-growing season. In this study, the soil C content, density and stability were examined across five coastal plant communities—Spartina alterniflora, Suaeda salsa, Phragmites australis, mixed S. alterniflora–S. salsa communities and bare flat in the non-growing season in Yancheng, Jiangsu Province, China. The S. alterniflora community exhibited elevated soil organic and inorganic C contents, owing to its high biomass, strong C retention capacity and reduced bacterial abundances. The P. australis community showed higher dissolved organic C and microbial biomass C contents, driven by increased soil moisture and inorganic nitrogen (N) that promote microbial decomposition of plant residue. The S.salsa community had the lowest soil organic C density due to its low aboveground biomass, soil moisture and inorganic N and jointly microbial effects. However, the highest soil inorganic C density in bare flat was due to high soil moisture and microbially mediated stabilization of recalcitrant C. The lowest resistance index of C in P. australis community was associated with low electric conductivity, high C and N availability and bacterial effects. Soil C fractions, densities and resistance index of C decreased with soil depth, likely reflecting reduced water and N availability that constrain root and microbial activities. The results suggest that the S.alterniflora community enhances soil C accumulation, while P. australis community accumulate more labile C fractions, evoking low C stability due to interaction between soil physicochemical and microbial properties.

Land tillage disturbances and nutrient enrichment severely alter ecosystem processes and functions. Previous studies have investigated the effects of tillage disturbance and nutrient enrichment on plant communities and soil properties. However, integrated studies of the effects of tillage disturbance and nutrient enrichment on multiple below-ground ecological processes and functions are needed. Here, we conducted a field experiment in the Hulunber grassland, setting up four treatments (control, tillage disturbance (D), nutrient enrichment (NPKμ) and tillage disturbance plus nutrient enrichment (NPKμD)) to study the effects of tillage disturbance and nutrient enrichment on plant communities, soil microbial communities, and carbon mineralization. Compared to D treatment, NPKμD treatment increased plant community biomass through a significant 13-fold rise in annual and biennial plant biomass (p < 0.01). D treatment and NPKμD treatment significantly decreased the Shannon index of plant communities (p < 0.05). Microbial network complexity increased under NPKμ treatment whereas D treatment decreased it. Both D treatment and NPKμ treatment significantly reduced soil carbon mineralization, and NPKμ exacerbated the negative effects of tillage disturbance (p < 0.05). Partial Least Squares Path Modeling showed that plant diversity, biomass and soil properties influenced soil carbon mineralization directly and indirectly through soil bacterial and fungal communities. Our study suggests that nutrient enrichment promotes the recovery of plant community productivity after disturbance, while the recovery of plant diversity and soil microbial community structure may take a longer period. Therefore, achieving comprehensive ecological integrity characterized by stable plant community structure and healthy soil microbial communities requires long-term monitoring and targeted management measures.

Artificial light at night has become a common occurrence globally and may increase the risk of plant invasion. However, the effects of different intensities of artificial light at night on the growth of invasive and native plants are unclear. We individually cultivated five pairs of invasive and native plants from different families under ambient light, low artificial light at night, and high artificial light at night. Our study showed that the total biomass of both invasive and native plants increased significantly under low artificial light at night. However, while the total biomass of invasive plants increased significantly, that of native plants was significantly decreased under high artificial light at night. These findings indicate that invasive plants can better utilize light energy and have more effective photosynthetic response mechanisms under artificial light at night, while the photosynthesis of native plants is inhibited. The leaf dry matter content, and leaf nitrogen content of invasive plants were significantly higher than those of native plants under artificial light at night, and artificial light at night significantly improved the photosynthetic nitrogen use efficiency of invasive plants. This indicates that invasive plants have stronger phenotypic plasticity and nitrogen-distribution strategy under artificial light at night. In summary, the better physiological response of invasive plants compared with native plants under different intensities of artificial light at night may lead to the further spread of invasive plants in the ecosystem.

Spring frost involves low temperatures in spring. Research shows cold snaps can alter herbaceous plants' biomass allocation, impacting grassland ecosystems. However, the exact effects of frost timing and severity remain unclear. This study simulated spring frost based on characteristics of spring frost on the northern slope of the Tianshan Mountains to examine how alfalfa (Medicago sativa) and ryegrass (Lolium spp.) adjust biomass allocation under varying frost intensities and timings, including interspecific differences in these responses. The findings revealed that (1) compared to the control group (which did not undergo low-temperature treatment), alfalfa was more sensitive to high-intensity spring frost, exhibiting a significant decrease of 13.6% in the root weight ratio and increases of 8.65% and 4.96% in the stem and leaf weight ratios, respectively. In contrast, ryegrass displayed an inverse trend, although the changes were not significant. (2) Early stage spring frost (immediately after thinning) significantly affected alfalfa biomass allocation, leading to an 11.28% decrease in the root weight ratio, whereas it also significant increases of 3.78% the stem weight ratio by 7.51% and leaf weight ratio. In contrast, late stage spring frost (applied on the 17rd day after thinning) had a relatively greater effect on ryegrass, with the root weight ratio increasing by 4.13% and the stem weight ratio decreasing by 4.18%. These findings reveal plants' distinct adaptations to cryogenic stresses, improving our understanding of herbaceous growth responses to extreme weather in arid zones and offering data to support grassland ecosystem services in Xinjiang.

Microclimate can profoundly impact carbon (C) cycling in terrestrial ecosystems. However, due to the complex thermal conduction among air, water, and sediment, the responses of wetland microclimate to the driving forces of global change remain largely unexplored. Here, based on a two-year (2022-2023) field manipulative experiment in a freshwater wetland in the North China Plain, this study aimed to investigate the effects of simulated climate warming and atmospheric nitrogen (N) deposition on the temperatures of shallow-water, deep-water, and sediment. The nighttime warming effect increased the daily mean temperatures of the shallow-water, deep-water, and sediment layers by 0.71°C, 0.73°C, and 0.64°C, respectively. In addition, the diurnal temperature range of the deep-water layer was reduced by 0.17°C. In contrast, N addition did not affect the above parameters of shallow-water, deep-water, or sediment. The impact of N addition showed seasonal fluctuations. Warming-induced temperature increase was influenced mainly by solar radiation and water turbidity. Changes in submerged plant cover had a cooling effect at various vertical levels. In addition, increased wetland temperature may affect the rate of microbial metabolism to significantly increase the rate of carbon emissions. The present study offers empirical evidence concerning temperature changes at varying vertical levels within freshwater wetlands in the context of climate warming. Our findings emphasize the necessity of integrating data on shallow-water, deep-water, and sediment temperatures into the forecasting of wetland carbon cycling responses to global change.

Co-existing forest tree species associated with ectomycorrhizal (ECM) or arbuscular mycorrhizal (AM) fungi may have different nitrogen (N) acquisition strategies for various soil nitrogen (N) forms which can be difficult to determine under field conditions. Paired (ammonium/nitrate) ¹⁵N labeling to soils demonstrated that common conifers in Northeast China associated with ECM fungi took up more nitrate than ammonium. The N uptake strategy of co-existing broadleaved species, associated with either AM fungi or ECM fungi, remains to be determined. We conducted paired ¹⁵N labeling on seedlings of six common broadleaved species and four conifer species to reveal more nitrate uptake than ammonium by all ten species. Nitrate uptake contributed 49~83% (average 69%) to N uptake by these species, ranking in the order of AM broadleaved species (average 79%), ECM broadleaved species (average 70%) and ECM conifer species (average 60%). Random forest analysis suggested plant functional groups, mycorrhizal types and fine root to shoot ratios as important factors supporting the higher nitrate uptake by these species. Our results provided convincing evidence of substantial nitrate assimilation to different extents by common conifer and broadleaved tree species in Northeast China.

Leaf chemistry is known to affect phyllosphere microbiomes. Plant populations often evolve genetic differences in leaf chemistry across regions, driven by both abiotic and biotic factors, including insect herbivory. Plants in invasive populations may reassociate with native specialist insects, providing an ideal system to examine chemical-mediated plant-herbivore-phyllosphere microbiome interactions. Here, we conducted a common garden experiment using Ambrosia artemisiifolia populations differing in leaf chemistry and reassociation history with a specialist beetle to investigate how these variables correlate with phyllosphere microbial community diversity and composition. Plants from populations with a longer reassociation history had higher herbivore resistance and more complex phyllosphere communities with higher alpha diversity. These changes were correlated with shifts in concentrations of plant metabolites and expression levels of their underlying biosynthetic genes. The abundance of one of the fungal pathogens, Golovinomyces, decreased with the observed increase in resistance to the herbivore, however, another one, Pestaliopsis, showed the opposite pattern. While reassociation history was linked to population latitude, climatic and soil conditions at the sites of origin also contributed to between-population variation in leaf chemistry and phyllosphere fungal community composition. Our study suggests that genetic differences in leaf chemistry between plant populations can strongly affect herbivore resistance as well as phyllosphere fungal community diversity and composition. Because the variations in invasive plant leaf chemistry aligned with the time since the invasive plant populations were reassociated with the herbivore, it is conceivable that selection imposed by the herbivore may have contributed to the variation in herbivore resistance and phylloshpere communities.

The groundwater depth can affect the composition and structure of plant communities. However, effects of the groundwater depth on the characteristics of shrub–grass communities in muddy coastal zones remain uncertain. We conducted a field experiment to evaluate effects of the different groundwater depth, which included 0.54 m, 0.83 m, 1.18 m, 1.62 m, and 2.04 m, on soil salinity, soil moisture, community diversity, distribution pattern and growth of the dominant Tamarix chinensis in the muddy coastal zone of Bohai Bay. Our results showed that (1) the soil moisture and salinity gradually decreased with increasing groundwater depth (P<0.001); (2) The Simpson, Shannon‒Wiener, Pielou and Margalef indices of the T. chinensis communities were greatest in the plots with 1.62 m; (3) The dominant shrub T. chinensis population exhibited an aggregated distribution and optimal growth of T. chinensis shrubs emerged in the plots with 1.18 m or 1.62 m; (4) The groundwater depth affected the diversity of the plant community mainly by influencing soil salinity rather than moisture; the dominant shrub T. chinensis promoted diversity of plant community, but this facilitation effect was inhibited by soil salinity. Our results suggest that the optimal groundwater depth for maintaining biodiversity falls within the range of 1.18 to 1.62 m. Shallow groundwater diminishes biodiversity both directly through soil salinization and indirectly by impairing T. chinensis’ facilitation of biodiversity. Therefore, maintaining optimal groundwater levels and protecting T. chinensis are critical for biodiversity conservation and ecosystem recovery in muddy coastal areas.

Traditional studies of plant elemental composition have mainly focused on the concentrations of C, N and P and stoichiometric ratios among different plant species. Little attention was paid to the intraspecific variation of the elementome and the underlying mechanisms including phenotypic plasticity and adaptive evolution. We conducted salinity manipulation experiments in two common gardens with two lineages of a widespread grass (Phragmites australis), measuring ten element concentrations of the leaves and roots. The genetic distances and epigenetic distances were calculated from SSR and MS-AFLP markers, respectively. In a principal component analysis, the root elemental contents contributed to the first two principal components (PC1 and PC2), and the leaf elemental contents contributed to PC3 and PC4. The PC1 was affected by salinity, while the PC2 was affected by salinity, climate and their interaction. The PC3 was affected by salinity, while the PC4 was affected by lineage. Mantel tests showed a significant correlation between epigenetic and environmental distances as well as between epigenetic and genetic distances. The contribution of genetics to epigenetic variation was larger than the environment. Genetic and epigenetic variation was associated with different PCs. The elementome is decoupled between leaf and root, and the root elementome had a larger variability. The leaf epigenetic variation depends on the genetic variation, and is also induced by the external environmental changes. Intraspecific elementome variation reflects environment more than genetic and epigenetic variation. These insights shed light on the underlying ecological mechanisms that drive the intraspecific variation of the elementome.

Litsea coreana Levl. var. sinensis has developed four heteromorphic leaf types to adapt to the local environment. This study investigated functional traits of four heteromorphic leaf types through morphological, anatomical, photosynthetic, and activity compounds to elucidate their niche differentiation within a single tree. Lanceolate (La) type had the largest leaf length (LL = 8.43 cm), leaf shape index (LSI = 2.85), leaf perimeter (LP = 18.51 cm), but low palisade tissue thickness (TPTT), light saturation point (L_SP), and light compensation point (L_CP), suited for varied positions and mild, humid climates. Ovoid (Ov) and orbiculate (Or) types had highest leaf thickness (LT = 0.2 mm) and high TPTT (66.93 and 63.97 μm), high chlorophyll (0.695 and 0.696 mg/g), high net photosynthetic rate (P_Nmax = 8.140 and 6.618 μmol·m^-2·s^-1), high Total flavonoid content (TFC = 45.216 and 47.704 mg/g), adapting top and edge canopy positions amid high temperatures and sun. Oblanceolate (Ob) type had largest SLA (117.22 cm²/g) and high dark respiration rate (R_d), but low TPTT and chlorophyll, adapting for shade in the lower canopy. As the LL increased the LSI progressively increased. As the TPTT, the P/S (Palisade/Spongy) gradually increases. As the L_SP, the P_Nmax gradually increases. Three principal components were extracted with a cumulative contribution of 75.196%, of which the Ov type had the highest composite principal component score. Our findings provide evidence that the presence of heteromorphic leaf types facilitates the utilization of different microhabitat by L. coreana Levl. var. sinensis.

Microplastics in terrestrial ecosystems are relatively understudied compared to microplastics in well-studied marine and freshwater ecosystems. It is well-documented that soil microplastics can profoundly influence agricultural plant species; while terrestrial wild plants are primary producers and at the bottom of food chains, remarkably little is known about how microplastic abundances affect their growth and the related mechanisms. We selected 18 wild plant species, exposed them to an environmentally realistic microplastic gradient (ranging from 0 to 8000 items kg^–1 soil) for one growing season, and measured soil pH, nutrients and microbes, leaf fluorescence, and plant biomass. We also used structural equation modeling to link the associations between variables. 11% of the 18 wild plant species were inhibited by polypropylene (PP) microplastics, 39% were facilitated, and 50% were unaffected. Across all the 18 species, PP microplastics had no negative impacts on their whole-plant growth, as measured by the standardized effect size; microplastic abundance impacts on whole-plant growth exhibited hump-shaped reaction norms, and the abundance thresholds for positive impacts approximately ranged from 2000 to 6000 items kg^–1 soil. Soil pH played a key role in mediating microplastic impacts directly and indirectly by altering leaf chlorophyll and root nutrient uptake. These findings suggest that microplastic abundance thresholds could shape the whole-plant growth of terrestrial wild plants and microplastic abundance impacts might not rise consistently. Additionally, threshold effects highlight the importance of the full gamut of microplastic abundance gradients and provide insights into ecosystem management strategies.

Green stem photosynthesis is well known, but the effect of stem photosynthesis on plant growth and development remains uncertain. In this study, green stems of semiannual Rosa chinensis were subjected to a shading treatment to explore the effect of stem photosynthesis on the growth and biomass accumulation. The results showed that (1) Stem photosynthesis affected biomass accumulation and allocation in R. chinensis. The stem shading treatment decreased the biomass of R. chinensis by approximately 18.7%. The proportion of biomass allocated to the stems increased while the proportion of biomass allocated to the leaves and roots decreased. (2) Stem photosynthesis facilitates an increase in nonstructural carbohydrate concentration, chlorophyll a concentration and chlorophyll a/b of R. chinensis. (3) The net photosynthesis in the stems of R. chinensis was negative, and biomass accumulation was significantly positively correlated with the dark respiration rate in stems, indicating that stem photosynthesis fixed CO₂ released internally by respiration. This study reveals that stem photosynthesis in R. chinensis enhances biomass accumulation by promoting chlorophyll fluorescence and dark respiration rates in the stems. Furthermore, stem photosynthesis contributes to the balanced allocation of biomass by enhancing the proportional distribution of biomass to leaves and roots.

While the alerting effects of microbe-induced plant volatiles (MIPVs) to biotic stressors have been extensively studied, the ecological functions of MIPVs responding to abiotic stressors have received less attention. Using an interplant communication assay setup, we employed Phytolacca americana as a study species to investigate whether heavy metal-induced MIPVs released by the emitter plants contribute to metal tolerance in neighboring receiver plants. We found that high levels of manganese (Mn) stress increased the total MIPV emissions of plants cultivated in non-sterilized soil, in contrast to VOCs emitted by plants in sterilized soil. MIPVs produced by the Mn-stressed plants notably altered the hormonal profiles of the receiver plants, leading to increased similarity in soil microbial assembles and modification of CSR strategies. Consequently, the receiver plants exhibited enhanced tolerance to subsequent Mn stress, as evidenced by improved growth performance, increased antioxidant enzyme activities, and reduced membrane damage. By unraveling the mechanism underlying MIPV-mediated tolerance priming for neighboring plants, we reveal a key signal role of soil microorganisms involved in plant-plant communication. This study represents one of the initial efforts to elucidate the alerting effects of MIPVs induced by heavy metal stress on neighboring plants and its ecological consequences.

Seedling adaptation to precipitation change is of great significance for the development and succession of tropical forests under the global climate changes. Here, we conducted a field-based manipulative experiment to assess the performance of different functional seedling (Cassia siamea, N-fixing, and Syzygium hancei, non-N-fixing species) to altered precipitation pattern (control; wetter wet season, WW; delay dry season, DW) in a secondary tropical forest of southern China. The results showed that WW (wetter wet season) and DW (delay dry season) treatments significantly increased leaf mass per area (LMA) of S. hancei, however, precipitation treatment significantly decreased the leaf chlorophyll a concentration of C. siamea, while significantly increased leaf chl b and total chl contents of S. hancei. WW treatment significantly increased the relative grow rate (RGR) of height and total biomass of S. hancei seedling. Additionally, WW and DW treatments significantly increased the leaf soluble sugar concentrations of both seedlings, while DW significantly raised the starch concentration of leaf and coarse root of S. hancei. Moreover, DW treatment significantly enhanced leaf NSC concentrations of both seedlings in this tropical forests. It is surprising that WW treatment unregulated the allocation of soluble sugar, starch, and NSC of leaf and fine root in C. siamea. Thus, the variations of NSC storage and allocation among different tissues in two seedlings may directly reflect the different adapting mechanisms to altered precipitation pattern. Therefore, our results indicated that the S. hancei (non-N-fixing) seedling may adjust the NSC concentrations while the C. siamea (N-fixing) seedling may shift the NSC allocation among different organs adapting to the altered precipitation in the tropical forest.

Biochar is a highly effective soil amendment that has been widely used for ecological remediation and has shown great potential in promoting plant nutrient acquisition and growth. However, it remains unclear whether biochar addition influences competition between invasive and native plants and thus is suitable for restoration of communities invaded by exotic plants. We conducted a field experiment and a ¹⁵N labelling test to investigate the impact of biochar addition on N uptake of invasive Spartina alterniflora and native Phragmites australis under both intra- and interspecific competition. Biochar addition significantly promoted the NO₃⁻-N uptake rate of both P. australis and S. alterniflora under interspecific competition, and promoted the NH₄⁺-N uptake rate of both P. australis and S. alterniflora under both intra- and interspecific competition. However, biochar addition did not influence the competitive balance between S. alterniflora and P. australis. We conclude that biochar addition can enhance N uptake of both native and invasive plants, but cannot alter their competitive superiority in N acquisition or shift their N form preferences. The findings suggest that biochar application will not be useful if we target at restoring wetlands due to exotic plant invasions, as it cannot enhance the competitive advantages of natives over invasives. However, biochar may be applied if we target at restoring degraded wetlands caused by other disturbances such as such as salinization and nutrient impoverishment, as it will not enhance the competitive advantage of invasives over natives.

Increasing nitrogen (N) deposition exacerbates phosphorus (P) limitations in subtropical Chinese fir plantations, yet clonal mechanisms mediating root adaptation to heterogeneous P environments remain unclear. This study investigates the growth and metabolic responses of three clones (Y061/Y020: P-efficient; Y2C: P-sensitive) under N deposition and contrasting P distributions. Elevated N deposition enhanced aboveground and belowground biomass under heterogeneous P conditions, particularly enhancing Y061’s root length and surface area. Elevated N deposition significantly increased APase activity while decreasing organic acid secretion, particularly under homogeneous P-deficient conditions. Heterogeneous P supply amplified clonal divergence: P-efficient clones exhibited higher phosphorus absorption efficiency (PAE) than Y2C through root morphological plasticity, while N deposition upregulated APase activity but reduced total organic acids secretion. Metabolomic revealed N-driven shifts in exudate profiles, with lactic, malonic, succinic, and oxalic acid increasing while shikimic, quinic and malic acids decreased. Notably, nitrogen absorption efficiency (NAE) synergistically enhanced PAE under high N conditions. Clones Y061 and Y020 demonstrated superior N and P absorption capabilities, while clone Y2C prioritized enzymatic P mobilization in homogeneous deficiency but showed compromised growth. We demonstrate that N deposition restructures root foraging strategies along a “morphological-enzymatic” axis, where P-efficient clones exploit spatial nutrient heterogeneity through root proliferation rather than organic acid investment. These findings provide actionable solutions: (1) Deploying Y061 and Y020 clones in high-N regions improves productivity; (2) Mixed plantations mimicking heterogeneous P distribution enhance nutrient resilience. Our findings contribute to a deeper understanding of nutrient dynamics and providing targeted strategies for sustainable forestry in acidified subtropical soils.

The mechanisms of plant adaptation to environmental gradients have been the focus of ecological research, with environmental stresses driving coordinated or differentiated regulation of plant functional traits. Plant resource acquisition involves root trait plasticity and mycorrhizal symbiosis. However, root trait plasticity along precipitation gradients and root-mycorrhizal trade-offs remain unclear. We conducted community surveys along a west-east precipitation gradient in four natural grassland communities (alpine desert steppe, ADS; alpine steppe, AS; alpine meadow steppe, AMS; and alpine meadow, AM) on the plateau in northern Xizang Plateau. Six key root traits (root diameter, RD; root dry matter content, RDMC; root tissue density, RTD; specific root length, SRL; root branching intensity, RBI; and root length colonization percentage, RLC) were measured in 18 alpine plant species to investigate the coordination and trade-offs between root traits and mycorrhizal fungi along the precipitation gradient. Our results showed community-level declines in RDMC, RD, RTD, and RLC with increasing precipitation, contrasting with elevated RBI and SRL. Functional groups exhibited distinct patterns: grasses and legumes demonstrated root-mycorrhizal trade-offs, sedges displayed synergy, and forbs showed inconsistent responses. Divergent trends in plant root traits and mycorrhizal fungi were observed at the species level. Alpine plants in humid eastern meadows favored root elongation, while those in arid western desert steppe relied on radial growth and mycorrhizal fungal cooperation for resource acquisition. These findings highlight varied root absorption strategies among alpine plants along environmental gradients, supporting the importance of ecological niche diversification in maintaining alpine ecosystem diversity and stability.

A widely accepted perspective posits that an extension of the growing season enhances plant growth by increasing the duration of favorable environmental conditions under warming, which is described as an ecological effect. However, changes in growing season length can also influence plant functional traits and physiological processes, as suggested by the “leaf economics spectrum” theory, a physiological aspect frequently overlooked. Disentangling the ecological and physiological effects of growing season length on plant growth remains challenging due to their co-variation with climate factors. Here we explored the physiological effect through common garden experiments on the Qinghai-Tibetan Plateau. Our findings revealed a trade-off between growing season length and plant growth under controlled climatic conditions, a pattern further corroborated by satellite-based observations across most regions of the plateau. This trade-off was driven by a negative correlation between growing season length and photosynthetic efficiency, suggesting that an extended growing season does not necessarily translate into enhanced carbon assimilation. However, state-of-the-art dynamic global vegetation models failed to adequately capture this trade-off, underscoring the need to integrate the physiological effects of growing season length into these model frameworks for improved predictions of plant growth under climate change.

Trait-based functional diversity (FD) is an important predictor of tree species ecological multifunctionality (TS-EMF), but its relationship may be mediated by environmental factors. Currently, the study of threshold-dependent relationship between FD and TS-EMF along urban and suburban gradients and their environmental regulatory mechanisms is still quite limited. In this study, 12 typical tree species from urban and suburban forests in Shenyang were used to calculate TS-EMF by combining the multi-threshold and averaging method, and to assess community FD, aiming to reveal the role of FD on TS-EMF and how environmental factors regulate TS-EMF through FD and community-weight mean (CWM) traits. The results showed that urban TS-EMF was generally higher than suburban (P < 0.05). There were differences in the driving mechanisms of TS-EMF at different threshold levels, with air humidity (total effect: 0.435) and CWM P_n (net photosynthetic rate, relative importance: 24.42%) being the key drivers at high threshold levels. At low threshold levels, functional evenness (FEve) played a dominant role, but the extent to which influenced TS-EMF depended on the type and number of tree species within the TS-EMF threshold range. Notably, the effects of CWM P_n and FEve on TS-EMF showed threshold dependence, with thresholds of 61.18% and 64.47%, respectively. Additionally, the urban-suburban gradient could significantly influence the driving mechanism: the direct effect of environmental factors and CWM traits prevailed in urban forests, while suburban forests showed a multi-factorial cascade effect. The study showed that the formation of TS-EMF in urban forests is the result of multi-factorial coupling of traits, FD, and environment factors, and this finding provides a new theoretical perspective for understanding the ecosystem service drivers of urban forests.

We screened 161 eligible papers of experimental data across the Tibetan plateau for Meta-analysis, in order to systematically assess and validate potential application of plant resource allocation strategies, such as the optimal allocation hypothesis, the isometric allocation hypothesis, and the allometric allocation hypothesis under environmental changes, and to explore the effects of environmental factors (temperature change, grazing intensity) on plant resource allocation strategies in alpine grassland ecosystems on the Tibetan Plateau. Overall, we found that the aboveground and belowground growth relationship in alpine grasslands follows the allometric growth hypothesis, which was unaffected by warming, grazing and their interactions. In addition, the biomass transferred between aboveground and belowground, the former was decreased, while the later was increased under warming condition in alpine steppe implies that the resource allocation strategy in alpine steppe grassland may potentially follow the optimal allocation hypothesis. We further found that the effect of soil properties on biomass, not the biomass allocation, was different under warming and grazing condition in alpine grasslands, which further conforms the above conclusion. In addition, warming helped to mitigate the negative effects of grazing, which indicated that the interaction between warming and grazing is important in alpine grassland ecosystems. Overall, results of this study are of theoretical significance for understanding how moderate grazing affects the growth of plants in alpine grasslands under changing climate.

The allometric relationships between growth traits are critical to trees’ fitness, yet the mechanisms by which slope position affects tree growth and allometry remain poorly understood. This study examined growth traits and their allometric relationships in a 8-year-old Calocedrus macrolepis plantation in southwest China across three slope positions (upslope, mesoslope, and downslope). The measured growth traits included tree height (H), diameter at breast height (D), crown size (Crown), wood volume (V), and height under branch (HUB). The study also explored spatial variations in soil properties and microbial communities. Results showed that slope position altered allometric growth pattern, with larger allometric exponents at downslope for H, D and V relative to Crown and HUB, suggesting improved wood growth. Soil nutrient levels (nitrogen, phosphorus and available potassium) and microbial diversity, particularly the relative abundance of bacterial phyla such as Actinobacteria and Chloroflexi, were greater at mesoslope and downslope. Our study identified phosphorus and potassium as key drivers of enhanced allometric relationships. Functional groups like Endomycorrhizal and Ectomycorrhizal fungi, and functional groups involved in nitrogen cycling (Nitrogen respiration, Nitrate respiration), were strongly correlated with allometric exponents for D, V and Crown relative to HUB, suggesting their role in supporting structural growth and canopy expansion. These findings emphasize that variations in soil nutrients and microbial communities across slope positions regulate tree growth and allometry, with bacterial communities exerting a stronger influence than fungi. These insights contribute to sustainable forest management, particularly in optimizing planting site selection for improved tree growth in mountainous regions.

Invasions by non-native plant species are thought to be facilitated by factors like escape from specialized natural enemies and increased resource availability. However, the success of invasive plants also depends on interactions with native plants and soil organisms, including nematodes. Plants can experience both beneficial and harmful interactions with nematodes. Yet, research on how nematodes and nutrient levels interact to affect competition between invasive and native plants is lacking. We conducted a multi-species greenhouse experiment involving 10 invasive species and 20 native species to test the separate and combined effects of nutrient levels and nematodes on performance of individual invasive plant species, as well as their competition with native plant communities. High-nutrient conditions significantly enhanced the aboveground biomass (+119.4%), height (+26.9%), reproduction (+21.0%), and proportional aboveground biomass (+21.2%) of invasive plant species. Conversely, competition from native plant communities significantly reduced the mean aboveground biomass, height, and reproduction of the invasive species by 55.3%, 20.3%, and 13.5%, respectively. For invasive plants grown without competition, the high-nutrient treatment significantly enhanced total biomass and root diameter, although it decreased the root mass fraction, independent of nematode presence. Additionally, in the absence of competition, nematodes increased the specific root length of invasive plants by 3.6% under low-nutrient conditions but reduced it by 10.1% under high-nutrient conditions. These results indicate that nutrient enrichment, competition, and biotic interactions with nematodes can all play critical roles in shaping the growth and adaptive strategies of invasive plant species.

Invasive plants may exhibit priority effects and begin growth before native plants. Priority effects may be an important way that invasive species outcompete native plants. We tested priority effects on the invasive grass Smooth Brome Bromus inermis (cool season C₃), the cosmopolitan and invasive Bermuda grass Cynodon dactylon (warm season C₄) and a native grass species, Red Fescue Festuca rubra (cool season C₃), in the greenhouse. We grew each species alone, with a conspecific neighbor (intraspecific competition), concurrently with one of the two other heterospecifics (interspecific competition), and with a priority effect of one species being present 21 days before the heterospecific neighbor (priority effects). We recorded relative growth rates (RGR), as well as above- and belowground dry biomass. We also used a relative interaction index (RII) to determine the competitive abilities of each of these species. Smooth Brome was significantly heavier than Bermuda and Red Fescue, although Bermuda grass had the highest RGR of the three species. All three species showed stronger effects of intraspecific competition than interspecific competition. Most of the effects were competitive relative to plants grown alone. However, none of these three species exhibited priority effects, unlike a previous study. We conclude that increased competitive ability, particularly of Smooth Brome, may be sufficient to exclude native grasses.

Cactaceae is an important plant family in the semi-arid ecosystems of the Americas. However, few studies have analyzed their responses after wildfires. In this study, we assessed the survival rate and resprouting capacity of cacti from different growth forms one year after a wildfire in the Córdoba Mountains, central Argentina. Eight species are present in the study area, which were classified into four growth forms; then we established 158 plots and recorded the status (dead or alive) of each cactus, and size-related variables. We also documented microenvironmental characteristics (percentage cover of grasses, forbs, shrubs, rock and bare ground) and topographic information (slope and slope orientation) for each plot, estimating the resprouting capacity of each growth form. Survival rates and resprouting capacity varied among growth forms. The survival rate for arborescent growth form was 25%, while for globose, opuntioid and short columnar forms were 84%, 69% and 55%, respectively. Microenvironmental and topographic factors influenced resprouting capacity, though effects varied among growth forms. Globose growth form showed the highest recovery capacity after the wildfire, contrasting with arborescent growth form, of which only 2% of the individuals resprouted, predominantly on south- and north-facing slopes. In contrast, short columnar and opuntioid growth forms showed no significant relationship between survival or resprouting capacity, and the measured variables. These findings provide key insights into the role of fire in shaping cacti populations and highlight the need to consider species-specific and environmental interactions in conservation and management strategies for the Chaco forest.

Alpine regions sequester large vulnerable and unprotected soil organic carbon (SOC), determining its extreme sensitivity to global change and pivotal role in the carbon cycle. However, there is ongoing debate regarding how SOC storage and its stabilizing mechanism vary along altitudinal gradients. Here, we examined the SOC contents of soil aggregate and density fractions, and their interactions with climate, biology and soil properties along elevation (2100-3900 m) of western Yulong Mountain in southwest China. Results showed that SOC contents in bulk soils and heavy fractions significantly increased with elevated altitudes, whereas no changes in aggregates. The increasing Fe/Al oxides with altitudes might be responsible for such significant variations. While soil C-enzyme activities had strong effects on increasing SOC in macroaggregates (> 250 μm), aggregate stability (indicated by mean weight diameter and soil erodibility) mainly reduced SOC in microaggregates, silt and clay (< 250 μm). The structural equation models further showed that 57-91% of variations in SOC contents could be explained by environmental variables, with the Fe/Al oxides showing the strongest positive associations with SOC contents in bulk soils, light and heavy fractions. Taken together, our results emphasized positive impacts of mineral protection on the SOC stabilization at high altitudes. This not only offers novel insights into predicting soil C stability in alpine regions but also provides practical significance for soil C pool management across various altitudes.

Global warming and altered precipitation regimes may profoundly affect soil nitrogen (N) transformations. However, a comprehensive understanding of how soil N cycling responds to such climatic changes remains lacking, with few syntheses of field-based observations. Here, a meta-analysis was conducted using 755 paired data points from field observations worldwide to explore the effects of warming and altered precipitation on soil N transformation rates and to assess possible drivers of these effects. Warming positively affected the soil N mineralization and nitrification rates (+21.8% and +20.9%), but had no effect on the microbial immobilization rate. Similarly, increased precipitation accelerated soil N mineralization and nitrification (+10.2% and +9.4%), but did not alter microbial immobilization. In contrast, decreased precipitation did not affect any of the three N transformation rates. Moreover, warming effects on the N mineralization rate were mainly driven by the variations in soil moisture and soil total N content, while effects on the nitrification rate were regulated by changes in ammonia-oxidizing bacterial abundance. In addition, effects of increased precipitation on the N mineralization rate were largely dependent on changes in soil moisture and experimental manipulation characteristics, while effects on the nitrification rate were shaped by MAP, soil pH, ecosystem types, and treatment duration. Overall, increased temperature and precipitation accelerated soil N cycling and increased soil N availability, but decreased precipitation did not. These findings may improve predictions of biogeochemical cycling under future climate change scenarios.

Nitrogen (N) deposition alters the soil environment for forest trees, particularly in tropical regions, leading to variations in leaf traits. However, the adaptive responses of plantation tree species to chronic N deposition, via leaf traits modifications, remains poorly understood. We conducted a decade-long experiment involving N additions in two typical plantations dominated by Eucalyptus urophylla (EU) and Acacia auriculiformis (AA) in South China, to investigate species-specific leaf trait plasticity under N deposition. Our results showed that long-term N addition did not affect N and phosphorus (P) concentrations, sugar and starch levels, intrinsic water use efficiency (iWUE) and leaf mass per area (LMA), but lowered leaf total C content in both EU and AA. Moreover, it resulted in divergent traits between them, showing an increase in tannin and phenolics but a decrease in leaf water content (LWC) in AA but no such variations in EU. These differential responses were attributed to their unique leaf traits that EU contains high chemical defensive compounds and AA, as an N-fixing tree species, exhibits higher resource levels. The reduced leaf total C was redirected towards defense, without compromising iWUE through unchanged sugar and starch levels, particularly in AA. Our findings demonstrate that long-term N addition intensifies the coupling between C and water, resulting in a shift in C allocation in trees. Consequently, long-term N addition triggers different defensive strategies: a conservative defense in EU and an active defense in AA. This offers new insights into the adaptive mechanisms of forest plants under global change scenarios.

Arbuscular mycorrhizal fungi (AMF) and Bacillus play a crucial role in promoting the growth and defense of exotic plants, and their interaction may further enhance plant invasions. Soil nitrogen level is an important factor that affects the interaction. However, the effect of the interaction on the growth and defensive ability of exotic plants under different nitrogen levels remains unclear. In this study, a pot experiment was conducted using Rhizoglomus intraradices (RI) and Bacillus megaterium (BM), one of the dominant AMF and Bacillus in the rhizosphere of Flaveria bidentis, with three soil nitrogen levels (0, 3.75, 7.5 g m^-2) and four inoculation treatments (uninoculated, inoculation with RI, inoculation with BM, and co-inoculated with RI and BM). Significant correlations were observed between microbial inoculations and indicators of plant growth and defense across varying soil nitrogen levels. Co-inoculation notably enhanced both plant growth and defense compared to single inoculations, especially under the nitrogen concentration of 3.75 g m^-2. Specifically, compared to single inoculation, co-inoculation increased the biomass of F. bidentis by 8.27% and 16.4%, as well as the flavonoids concentration by 21.89% to 30.95% and phenolic acids concentration by 54.22% to 60.93%, respectively. These enhancements in growth and defensive compound production likely promote the competitive ability of F. bidentis and its resistance to biotic and abiotic stresses, thereby contributing to its successful invasion.

Drought represents a paramount abiotic stressor constraining global agroforestry productivity. Plants have evolved multifaceted adaptive strategies involving active modulation of symbiotic microbial communities to mitigate drought stress. These plant-associated microbes enhance plant drought adaptation via five principal mechanisms: 1) EPS-mediated biofilm formation on plant surface enhances hydroregulation and edaphic structural stability; 2) Osmoprotectant biosynthesis (e.g., proline) maintains cellular osmotic equilibrium; 3) Synthesizing antioxidants to reduce damage from reactive oxygen species and oxidative stress; 4) Regulating plant phytohormone metabolism by secreting hormones (e.g., IAA) and 1-aminocyclopropane-1-carboxylic deaminase (ACCD); 5) Emitting signaling molecules (e.g., volatile organic compounds, hormones, and enzymes) to activate plant drought adaptation. Future researches should focus on the development of host-specific drought-adaptive microbial consortia while elucidating phyllosphere-rhizosphere microbiome crosstalk , ultimately harnessing translational microbiome engineering to evaluate their efficacy in multi-environment agricultural systems.

The physiological response mechanisms of trees to climate change are complex, particularly across varying elevations and among different tree species. In this study, we collected tree ring samples from two dominant conifer species (Picea crassifolia and Pinus tabuliformis) at three elevations at the edge of the Tengger Desert. We used tree-ring width (TRW) and tree ring oxygen isotopes (δ¹⁸O_TR) to investigate how species and elevations affect their responses to climate change. Pearson's correlation analysis and relative importance analysis were used to study the specific response processes of the two conifers to climate. The results showed that the TRW was mainly controlled by SPEI during the growing season, which means that drought stress had the greatest effect on it. And δ¹⁸O_TR mainly responded to summer relative humidity (RH). Both TRW and δ¹⁸O_TR of Picea crassifolia showed higher sensitivity to climate change. This sensitivity is largely attributed to the rapid uptake of precipitation by its developed shallow-rooted root system, which allows it to retain the precipitation signal in both TRW and δ¹⁸O_TR. However, Picea crassifolia may be more susceptible to drought stress and growth decline or even death in the context of a warming region. Our results are important for understanding the impacts of climate change on forest ecosystems using multiple indicators and developing corresponding ecological conservation measures.

Plant reproductive phenology is sensitive to climate change and has great implications for plant reproduction, community structure and ecosystem functions. Shifts in reproductive phenology under warmer temperatures have been widely studied, but how other global change factors, such as nitrogen enrichment and altered precipitation, interact with warming to influence phenology remains poorly understood. We conducted a field experiment in a Tibetan alpine meadow to examine the effects of warming, nitrogen addition, precipitation reduction and their interaction on plant reproductive phenology in 2017 and 2021. We found that warming interacted with precipitation reduction to affect reproductive phenology, independent of nitrogen addition. Specifically, warming led to an advance in flowering (3.5 days) and fruiting onset (3.8 days), but precipitation reduction offset this effect. Warming also extended the duration of flowering and reproduction, but only when interacting with precipitation reduction. Nitrogen addition delayed the onset of flowering (2.1 days) and fruiting (1.8 days). Moreover, the effects of warming depended on the phenological niche of each species as well as its pollination mode. Early-flowering species advanced more in flowering onset than late-flowering species. The duration of flowering and reproduction of wind-pollinated species was prolonged while that of insect-pollinated species was shortened by warming. Our study highlights the necessity of considering the interaction of multiple factors in predicting phenological responses under global change and suggests that plant life-history traits should be taken into account in future studies.

Terrestrial plants are colonized by various microorganisms in the rhizosphere, phyllosphere and endosphere. Variations of microorganisms between these niches could affect plant performance. While studies have indicated that microorganisms associated with invasive plants may facilitate their invasion success, niche effects on the composition, function and co-occurrence network of invasive plant microbiomes remain poorly understood. In this study, we investigated the bacterial and fungal communities in the rhizosphere soil, root and leaf endospheres of two invasive plants, Flaveria bidentis and Eclipta prostrata. F. bidentis is a recently introduced species (introduced in 2001), whereas E. prostrata has been invaded in China for over 1000 years. We found that microbial community of F. bidentis and E. prostrata harbored more specialists, fewer unique amplicon sequence variants (ASV), and lower diversity and network complexity in the leaf endosphere than that in the rhizosphere soil. Moreover, the bacterial and fungal communities in the rhizosphere soil, root and leaf endospheres of F. bidentis were more diverse, included more unique ASVs, and had a higher network complexity than those of E. prostrata. Predicted functional profiles revealed that there were more beneficial bacteria and fewer pathogenic fungi associated with F. bidentis than those with E. prostrata. These results demonstrate that there is a significant niche differentiation in the two invasive plant microbiotas, and this work may also indicate potential impact of residence time of invasive plants on plant-microbe interactions.

Plant-soil feedback (PSF) effects of invasive plants are often regulated by abiotic factors, but whether soil water availability alters the impact of PSF on invasive plant growth and foliar herbivory remains unclear. We hypothesized that soil water content modifies PSF effects and then affects foliar herbivory. To test this, we established four soil water level treatments (soil surface elevated 0, 5, 10 or 15 cm above water) to examine their effects on PSF, growth traits, and herbivore resistance in the invasive weed Alternanthera philoxeroides. Results showed PSF was negative when soil surface was elevated 5 cm above water, but it was positive in other treatments. Soil condition, water treatment and their interactions significantly affected total biomass, leaf and branch numbers. As soil water content decreased, leaf nitrogen content increased, while the leaf C/N ratio decreased. Root nitrogen and C/N ratios were also affected by water treatment. Leaf mass per area and leaf area consumption rate were significantly affected by water content, with foliar herbivory being lowest when water content was at its minimum. Importantly, the effects of water availability on invasive plant performance and foliar herbivore resistance appeared to be stronger than those mediated by soil feedback. These findings suggest that soil water content, as a critical role, modifies the PSF effects on invasive plant performance, thereby indirectly affecting foliar herbivory.

While substantial nitrogen (N) input from yak urine in intensively grazed grasslands on the Qinghai-Tibetan Plateau (QTP) is well documented, the species-specific responses of dominant forage plants—particularly regarding N uptake efficiency, environmental impacts, and associated microbial dynamics—remain poorly understood. This study investigated Elymus nutans (Gramineae) and Kobresia graminifolia (Cyperaceae), two ecologically dominant species, to elucidate the divergent nitrogen transformation features under urine deposition. During the growing season, we simulated yak urine input by applying 640 mL urine per 40 cm × 40 cm patch in natural grasslands. Over six weeks, we measured total plant N uptake and soil nitrous oxide (N₂O) emissions, and evaluated soil nitrification rates through a two-week indoor incubation experiment. To elucidate the underlying microbial mechanisms, we analyzed the abundance and composition of rhizosphere ammonia-oxidizing archaea (AOA) and bacteria (AOB). Results showed that K. graminifolia exhibited significantly lower soil nitrification rates and N₂O emissions but higher total N uptake compared to E. nutans. Furthermore, K. graminifolia soil had lower AOB and higher AOA abundances. Specifically, the relative abundances of Nitrosophaera and Candidatus Nitrosocosmicus within AOA, as well as Nitrosovibrio and Nitrosomonas within AOB, were higher in K. graminifolia soil. These findings indicate that variations in nitrifier populations may be key drivers of differences in N uptake and N₂O emissions across dominant forage species. This study provides valuable insights for developing effective management strategies for intensively grazed grasslands on the QTP.

The north-south transitional zone in central China is a climatic and ecological sensitive area, and the southern margin of Pinus tabulaeformis distribution, yet regional response to climate has not been investigated. Here we developed different regional chronologies from 14 samplings along an east-west gradient in the Funiu Mountains. Correlation results indicated that regional tree growth was mainly limited by temperature and precipitation in May, especially for YM. Temperature in the south and precipitation in the north were significant limiting effects, except in LCM where trees were more limited by temperature in the south than precipitation in the north. The limiting effect of temperature in May gradually weakened from east to west, while the effect of precipitation in May was higher in YM (east) and BB (west) than in LCM (middle), and the promoting effect of precipitation in the north was stronger than that in the south. The self-calibrating Palmer Drought Severity Index (scPDSI) had significant positive correlations with tree growth from April to June, with the highest correlation in May. Tree growth increased in the 1970s-80s and then decreased after the 1990s indicated that the growth had degraded under global warming. This result supports the ecological marginal effect theory of growth degeneration of P. tabuliformis in NSTZ under global warming. However, whole regional tree growth also showed stronger recovery and resilience under extreme drought, the resilience basically restored to the pre-disturbance level after three years, which is obviously contradictory with tree growth trend and needs to be further studied.