Phylosymbiosis, the congruence of microbiome composition with host phylogeny, is a valuable framework for investigating plant–microbe associations and their evolutionary ecology. This review assesses the prevalence of phylosymbiosis across the plant kingdom, elucidates the fundamental ecological and evolutionary processes contributing to its occurrence based on previous research and explores commonly used methods for identifying phylosymbiosis. We find that the presence of phylosymbiosis may be influenced by both phylogenetic distance and the taxonomic level at which host plants are examined, with the strength of associations potentially decreasing as the taxonomic scale becomes finer. Notably, the endophytic microbiome exhibits a stronger phylosymbiosis signal compared with the epiphytic or rhizosphere-associated microbiomes. Microorganisms such as fungi and bacteria can yield highly variable evidence for phylosymbiosis due to differences in colonization, transmission or functional characteristics. We also outline how the four community assembly processes (dispersal, selection, diversification and drift) contribute to the establishment and maintenance of host–microbe phylosymbiosis. Furthermore, we highlight the diversity of methods employed to detect phylosymbiosis, which involves three key processes: constructing host phylogenies, assessing microbial data and statistically evaluating the correlation between host phylogeny and microbial composition. Remarkably different methodologies across studies make comparisons between findings challenging. To advance our understanding, future research is expected to explore phylosymbiosis at lower taxonomic levels and investigate different microbial communities coexisting synergistically within the same host. Understanding the relative importance of community assembly processes in driving phylosymbiosis will be critical for gaining deeper insights into the ecology and evolution of host–microbe interactions.

The decline in tree growth has become a global issue. It is critically important to explore the factors affecting tree growth under the background of global climate change to understand tree growth models. A database was established based on Robinia pseudoacacia growth and its driving factors on China’s Loess Plateau. Linear regression and three machine learning methods, including support vector machine, random forest (RF) and gradient boosting machine were used to develop R. pseudoacacia growth models considering forest age, density, climate factors and topographic factors. The root mean square deviation method was adopted to quantitatively assess the relationship between tree growth and soil properties. The average tree height of R. pseudoacacia on the Loess Plateau was 8.8 ± 0.1 m, the average diameter at breast height (DBH) was 10.4 ± 0.1 cm and the average crown diameter was 3.2 ± 0.1 m. The RF model was a fast and effective machine learning method for predicting R. pseudoacacia growth, which showed the best simulation capability and could account for 67% of tree height variability and 55% of DBH variability. Model importance indicated that forest age and stand density were the main factors predicting R. pseudoacacia growth, followed by climate factors. The trade-off between R. pseudoacacia growth and soil properties revealed that soil texture and soil pH were the primary determinants of R. pseudoacacia growth in this region. Our synthesis provides a good framework for sustainable forest management in vulnerable ecological areas under future climate change.

Plants typically experience great losses from their reproductive potential represented by ovule production to the post-dispersal crop of viable seed. We examined seed density and viability in a founder population of mountain birch (Betula pubescens ssp. tortuosa), aiming to quantify losses at different stages and examine potential selection forces on the reproduction success of the founder generation of an isolated population. At the time of the study (2017–2020), the population had recently reached reproductive maturity, following its colonization around 1990 through long-distance dispersal onto an early successional outwash plain in southeast Iceland. Seed densities were high, but 89% of apparently intact seeds did not contain an embryo, despite being visually indistinguishable from flled seeds. Externally evident losses amounted to about 45% of the total seed crop and were mostly due to predation by the gall midge Semudobia betulae. When all losses were accounted for, 2.7% of the seed crop remained viable and germinated. Pollen limitation may partially explain the high incidence of empty seeds. Excessive fower production is compatible with the predator satiation hypothesis but cannot explain pre-dispersal losses. Another adaptation to predation, masting, appears poorly developed in Iceland. Our results suggest the presence of constraints on the reproduction potential of the new island population, that are more limiting than in neighbouring populations, and we discuss their developmental, ecological, and environmental correlates.

The mating systems and floral traits often among relatives of hermaphroditic plants can exhibit considerable diversity. This diversity can be influenced by the evolution of selfing and associated floral traits as a form of reproductive assurance (RA) when pollen limitation (PL) results from insufficient pollinator availability. To explore whether the degree of PL primarily drives differences in mating systems and floral traits, we conducted a comprehensive study involving two closely related species, Halenia elliptica and Halenia grandiflora, in three sympatric sites. We investigated floral characteristics, pollinator visitation, PL, autonomous selfing ability, RA and mating system in studied populations. Our findings show that H. elliptica produces smaller flowers and less nectar production than H. grandiflora, making it less attractive to pollinators. Compared with H. grandiflora, H. elliptica experienced more severe outcross pollen limitation (OPL), but compensates with a higher capacity for autonomous selfing, ensuring seed production under natural conditions. Moreover, significant differences in mating systems were detected between them, with H. elliptica exhibiting a higher selfing rate than H. grandiflora across all studied sympatric populations. These differences are also reflected in variations in herkogamy and dichogamy. Our study suggested that the degree of OPL impacts the divergence in mating systems and floral traits between sympatric closely related species, offering valuable insights into the evolution of plant mating systems and floral traits.

Grazing exerts a profound influence on both the plant diversity and productivity of grasslands, while simultaneously exerting a significant impact on regulating grassland soil carbon sequestration. Moreover, besides altering the taxonomic diversity of plant communities, grazing can also affect their diversity of functional traits. However, we still poorly understand how grazing modifies the relationship between plant functional diversity (FD) and soil carbon sequestration in grassland ecosystems. Here, we conducted a grazing manipulation experiment to investigate the effects of different grazing regimes (no grazing, sheep grazing (SG) and cattle grazing (CG)) on the relationships between plant FD and soil carbon sequestration in meadow and desert steppe. Our findings showed that different livestock species changed the relationships between plant FD and soil organic carbon (SOC) in the meadow steppe. SG decoupled the originally positive relationship between FD and SOC, whereas CG changed the relationship from positive to negative. In the desert steppe, both SG and CG strengthened the positive relationship between FD and SOC. Our study illuminates the considerable impact of livestock species on the intricate mechanisms of soil carbon sequestration, primarily mediated through the modulation of various measures of functional trait diversity. In ungrazed meadows and grazed deserts, maintaining high plant FD is conducive to soil carbon sequestration, whereas in grazed meadows and ungrazed deserts, this relationship may disappear or even reverse. By measuring the traits and controlling the grazing activities, we can accurately predict the carbon sequestration potential in grassland ecosystems.

Invasive plants usually experience population differentiation as they expand from their initial invasive range to the edge. Moreover, invasive plants usually encounter competitors which shared different co-evolutionary histories with them. These factors may lead to varying responses of invasive plant populations to elevated nitrogen deposition during expansion. However, this issue has received limited attention in prior research. To address these challenges, we conducted a greenhouse experiment to investigate how population differentiation of Galinsoga quadriradiata interacts with the presence of various competitors in response to increased nitrogen deposition. Competitor types (new or old that shared short or long co-evolutionary history with the invader, respectively) were set to compete with the invasive central and edge populations under different nitrogen addition treatments. Individuals from the central population of G. quadriradiata, originating from the initial invasion range, showed greater total mass, reproduction and interspecific competitiveness compared with the edge population. Nitrogen addition improved growth and reproductive performance in both populations, and the central population had a stronger response compared with the edge population. The performance of G. quadriradiata was inhibited more effectively by old competitors than new competitors. Our results indicate that population differentiation occurs in terms of growth and competitiveness during the range expansion of G. quadriradiata, with the central population exhibiting superior performance. Co-evolutionary history with competitors is considered unfavorable for invasive plants in this study. Our results highlight the combined effects of population differentiation in invasive species and their co-evolution history with competitors in the context of global change factors.

Estimating the effects of extreme drought on the photosynthetic rates (Pn) of dominant plant species is crucial for understanding the mechanisms driving the impacts of extreme drought on ecosystem functioning. Extreme drought may result from either reduced rainfall amount or decreased rainfall frequency, and the impacts of different patterns of extreme drought may vary greatly. In addition, different grasslands likely appear various sensitivity to different extreme drought patterns. However, there have been no reports on the effects of different extreme drought patterns on dominant species Pn in different grassland types. Here, we conducted multi-year extreme drought simulation experiments (reducing each rainfall event by 66% during the growing season, CHR vs. completely excluding rainfall during a shorter portion of the growing season, INT) in two different grasslands (desert grassland vs. typical grassland) from 2014. The Pn of two dominant species in each grassland was measured in July and August 2017. Both CHR and INT significantly decreased dominant species Pn, with INT causing more negative impacts on Pn regardless of grassland types. The response ratios of Pn in desert grassland were generally higher than that of typical grassland, especially for Leymus chinensis in CHR. These results demonstrated that decreased rainfall frequency had a more negative effect on Pn compared with reduced rainfall amount, with grassland types changing the magnitude, but not the direction, of the effects of extreme drought patterns. These findings highlight the importance of considering extreme drought patterns and grassland types in ecosystem management in the face of future extreme droughts.

Biological invasions by alien and range-expanding native plant species can suppress native plants through allelopathy. However, the homeland security hypothesis suggests that some native plants can resist invasion by producing allelopathic compounds that inhibit the growth of invasive plants. Most research has focused on allelopathic interactions between individual native and invasive plant species, with less emphasis on how allelopathy helps entire native communities resist invasions. Additionally, limited knowledge exists about allelopathic interactions between range-expanding native species and recipient native communities, and their influence on invasion success. To bridge this knowledge gap, we conducted two greenhouse competition experiments to test reciprocal allelopathic effects between a native woody range-expanding species, Betula fruticosa, and a community of four native herbaceous species (Sanguisorba officinalis, Gentiana manshurica, Sium suave, and Deyeuxia angustifolia) in China. We assessed whether B. fruticosa and the native community differed in their competitive effects and responses, and whether these were influenced by activated carbon, which neutralizes allelochemicals in the soil. Activated carbon reduced the suppressive effects of the native community on the above-ground biomass of B. fruticosa, which indicates that the native community exerted a strong allelopathic effect on B. fruticosa. In contrast, activated carbon only marginally enhanced the suppressive effects of B. fruticosa on the native community, which indicates that allelopathy is not the primary mechanism by which B. fruticosa exerts its suppression. Overall, these findings support the homeland security hypothesis and suggest that biotic resistance from the native herbaceous community may limit the invasion success of the woody range-expander B. fruticosa.

The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models (LSM). Particularly in high-altitude regions, choosing appropriate atmospheric forcing datasets can effectively reduce uncertainties in the LSM simulations. Therefore, this study conducted four offline LSM simulations over the Tibetan Plateau (TP) using the Community Land Model version 4.5 (CLM4.5) driven by four state-of-the-art atmospheric forcing datasets. The performances of CRUNCEP (CLM4.5 model default) and three other reanalysis-based atmospheric forcing datasets (i.e. ITPCAS, GSWP3 and WFDEI) in simulating the net primary productivity (NPP) and actual evapotranspiration (ET) were evaluated based on in situ and gridded reference datasets. Compared with in situ observations, simulated results exhibited determination coefficients (R²) ranging from 0.58 to 0.84 and 0.59 to 0.87 for observed NPP and ET, respectively, among which GSWP3 and ITPCAS showed superior performance. At the plateau level, CRUNCEP-based simulations displayed the largest bias compared with the reference NPP and ET. GSWP3-based simulations demonstrated the best performance when comprehensively considering both the magnitudes and change trends of TP-averaged NPP and ET. The simulated ET increase over the TP during 1982–2010 based on ITPCAS was significantly greater than in the other three simulations and reference ET, suggesting that ITPCAS may not be appropriate for studying long-term ET changes over the TP. These results suggest that GSWP3 is recommended for driving CLM4.5 in conducting long-term carbon and water processes simulations over the TP. This study contributes to enhancing the accuracy of LSM in water–carbon simulations over alpine regions.

As a crucial strategy for sustainable agricultural production, green manure–crop rotation can regulate soil nutrient cycling and decrease the reliance on nitrogen fertilizers. However, we still lack a comprehensive understanding of the changes in soil eco-enzyme activities, microbial metabolism and nutrient limitations caused by leguminous green manure–crop rotation. Here, we conducted field experiments of leguminous green manure–crop rotation across China to analyze soil extracellular enzyme activities, specifically β-glucosidase (BG), N-acetyl-β-d-glucosaminidase (NAG), leucine aminopeptidase (LAP) and acid phosphatase (AP). The study revealed that long-term green manure–crop rotation increased carbon and nitrogen accumulation in farmland, with a significant average increase of 20.1% and 36.4% in BG, AP enzyme activities in topsoil, while showing a decrease in ln(NAG + LAP):ln(AP) ratios. The ratios of ln(BG):ln(NAG + LAP) and ln(NAG + LAP):ln(AP) in soil across various regions were typically below 1:1, indicating that soil microbial activity is more constrained by nitrogen and phosphorus nutrients rather than by carbon. Precipitation, temperature, soil total carbon (TC) and total nitrogen (TN) were identified as key environmental factors for extracellular enzyme activities and stoichiometric ratios. Our study highlights that the green manure–crop rotation alleviates nitrogen limitation while enhancing phosphorus limitation, and is closely related to the accumulation of TC and TN in the soil.

Asymmetric seasonal warming, characterized by more pronounced temperature increases in winter than in summer, has become a critical feature of global warming, especially in cold and high-altitude regions. Previous studies have primarily focused on year-round warming, while comparatively less attention was paid to winter warming. However, a significant knowledge gap exists regarding the impacts of winter warming on ecosystem functions. To address this, we conducted an 8-year manipulated warming experiment in an alpine grassland on the Tibetan Plateau, employing three treatments: no warming, year-round warming and winter warming. We found that neither year-round warming nor winter warming significantly alters species richness at the community level. Notably, community biomass stability was maintained via species asynchrony. However, warming exerted significant effects on the plant abundance groups (dominant, common and rare species). Specifically, winter warming enhanced the stability of dominant species by increasing species asynchrony of dominant species, as the compensatory dynamics occurred between the grass and forbs. In contrast, year-round warming reduced the stability of common species, correlated with an increase in species richness and a decline in asynchrony among common species. Thus, our study underscores the capacity of alpine grassland to maintain community biomass stability via asynchrony dynamics of species under different warming conditions, although the stability of different abundance groups would be changed. Importantly, our results provide valuable insights for understanding the alpine grassland ecosystem on the Tibetan Plateau.

In the Eurasian forest-steppe, with increasing aridity, the balance between naturally co-existing forest and grassland patches is expected to shift towards grassland dominance in the long run, although feedback mechanisms and changes in land-use may alter this process. In this study, we compared old and recent aerial photographs of Hungarian forest-steppes to find out whether and how the forest proportion and the number of forest patches change at the decadal time scale. The percentage area covered by forest significantly increased in all study sites. The observed forest encroachment may be a legacy from earlier land-use: due to ceased or reduced grazing pressure, forests are invading grasslands until the potential forest cover allowed by climate and soil is reached. The number of forest patches significantly increased at one site (Fülöpháza), while it decreased at two sites (Bugac and Orgovány) and showed no significant change at the fourth site (Tázlár). This indicates that forest encroachment can happen at least in two different ways: through the emergence of new forest patches in the grassland, and through the extension and coalescence of already existing forest patches. Though the present work revealed increasing tree cover at a decadal time scale, the dynamic process should be monitored in the future to see how the vegetation reacts to further aridification. This could help devise a conservation strategy, as the woody/non-woody balance has a profound influence on basic ecosystem properties.

Functional traits play a vital role in mediating the responses of ecosystem services to environmental changes and in predicting the functioning of the ecosystem. However, the connection between functional traits and ecosystem services has become increasingly intricate due to climate change and human activities for degraded ecosystems. To investigate this relationship, we selected 27 sampling sites in the Yanhe River Basin of the Chinese Loess Plateau, each containing two types of vegetation ecosystems: natural vegetation and artificial vegetation ecosystems. At each sampling site, we measured ecosystem services and calculated the composition index of community traits. We established a response–effect trait framework that included environmental factors such as climate, elevation and human activities. Our results showed that leaf tissue density (LTD) was the overlapping response and effect trait when responding to climate change. LTD is positively correlated with mean annual temperature and negatively correlated with supporting services. Under the influence of human activities, leaf nitrogen content and leaf dry matter content were carriers of environmental change. Comparing the two vegetation ecosystems, the relationship between functional traits and ecosystem services showed divergent patterns, indicating that human activities increased the uncertainty of the relationship between functional traits and ecosystem services. Trait-based ecology holds promise for enhancing predictions of ecosystem services responses to environmental changes. However, the predictive ability is influenced by the complexity of environmental changes. In conclusion, our study highlights the importance of understanding the complex connection between functional traits and ecosystem services in response to climate changes and human activities.

A meandering riverbank plays a vital role in maintaining natural river ecosystems, providing habitats for riparian vegetation. However, dams have significantly altered riverbank shapes. To restore the riparian ecosystems, it is imperative to understand how different riverbank curvatures influence them. This study aims to uncover the ecological impacts of riverbank curvature on the structure and assembly process of plant communities in the riparian zone of the Yangtze River, regulated by the Three Gorges Dam (TGD) in China. We categorized the riparian zones into four types: cove, lobe, wavy and linear shapes. We documented the composition and diversity of riparian plant communities. Our findings revealed that wavy and cove riverbanks exhibited greater species diversity (with Shannon–Wiener diversity index values 1.5× higher) compared to communities along linear riverbanks. Furthermore, the analysis of functional traits indicated that wavy riverbanks promoted the differentiation of plant functional traits, thus enhancing ecosystem functions, with functional dispersion index (FDis) values 1.3 times higher than those of linear riverbanks. Significant variations in the assembly of riparian communities were also observed among different riverbanks, with standardized effect size (SES) values indicating a higher degree of niche differentiation in cove riverbanks (SES = 0.4) compared to linear riverbanks (SES = –0.6). These results highlight the ecological importance of diverse riverbank curvatures in influencing the diversity, structure and assembly of riparian communities along the waterway. In summary, this study underscores the necessity of maintaining or restoring various natural morphological curvatures when rehabilitating riparian communities along rivers impacted by human activities.

The biomass of wetland plants is highly responsive to environmental factors and plays a crucial role in the dynamics of the soil organic carbon (SOC) pool. In this study, we collected and analyzed global data on wetland plant biomass from 1980 to 2021. By examining 1134 observations from 182 published papers on wetland ecosystems, we created a comprehensive database of wetland plant above-ground biomass (AGB) and below-ground biomass (BGB). Using this database, we analyzed the biomass characteristics of different climate zones, wetland types and plant species globally. Based on this, we analyzed the differences between the biomass of different plant species and the linkage between AGB and BGB and organic carbon. Our study has revealed that wetland plant AGB is greater in equatorial regions but BGB is highest in polar areas, and lowest in arid and equatorial zones. For plant species, the BGB of the Poales is higher than the AGB but Caryophyllales, Cyperales and Lamiales have higher AGB. Moreover, our findings indicate that BGB plays a more significant role in contributing to the organic carbon pool compared to AGB. Notably, when BGB is less than 1 t C ha⁻¹, even slight changes in biomass can have a significant impact on the organic carbon pool. And we observed that the SOC increases by 5.7 t C ha⁻¹ when the BGB content is low, indicating that the SOC is more sensitive to changes in biomass under such circumstances. Our study provides a basis for the global response of AGB and BGB of wetland plants to organic carbon.

Vegetation green-up is occurring earlier due to climate warming across the Northern Hemisphere, with substantial infuences on ecosystems. However, it is unclear whether temperature responses differ among various green-up stages. Using high-temporal-resolution satellite data of vegetation greenness and averaging over northern vegetation (30–75° N), we found the negative interannual partial correlation between the middle green-up stage timing (50% greenness increase in spring–summer) and temperature (R_P = −0.73) was stronger than those for the onset (15% increase, R_P = −0.65) and end (90% increase, R_P = −0.52) of green-up during 2000–2022. Spatially, at high latitudes, the middle green-up stage showed stronger temperature responses than the onset, associated with greater low-temperature constraints and stronger control of snowmelt on green-up onset as well as greater spring frost risk. At middle latitudes, correlations with temperature were similar between the onset and middle stages of green-up, except for grasslands of the Mongolian Plateau and interior western USA, where correlations with temperature were weaker for the middle stage due to water limitation. In contrast, the end of the green-up showed weaker temperature responses than the middle due to insuffcient water and high climatic temperature during the end of the green-up in most of the study region, except for cold regions in the interior western USA, western Russia and the Tibetan Plateau, where temperature was still a main driver during end of green-up. Our fndings underscore the differences in temperature responses among green-up stages, which alters the temporal alignment between plants and environmental resources.

Climate refugia can serve as a remnant habitat or stepping stones for species dispersal under climate warming. The largest freshwater lake by surface area, Lake Superior, USA and Canada, serves as a model system for understanding cooling-mediated local refugia, as its cool water temperatures and wave action have maintained shoreline habitats suitable for southern disjunct populations of arctic–alpine plants since deglaciation. Here, we seek to explain spatial patterns and environmental drivers of arctic–alpine plant refugia along Lake Superior’s shores, and assess future risk to refugia under moderate (+3.5 °C) and warmest (+5.7 °C) climate warming scenarios. First, we examined how the interactive effects of summer surface water temperatures and wind affected onshore temperatures, resulting in areas of cooler refugia. Second, we developed an ecological niche model for the presence of disjunct arctic–alpine refugia (pooling 1253 occurrences from 58 species) along the lake’s shoreline. Third, we fit species distribution models for 20 of the most common arctic–alpine disjunct species and predicted presence to identify refugia hotspots. Finally, we used the two climate warming scenarios to predict changes in the presence of refugia and disjunct hotspots. Bedrock type, elevation above water, inland distance, July land surface temperature from MODIS/Terra satellite and near-shore depth of water were the best predictors of disjunct occurrences. Overall, we predicted 2236 km of the shoreline (51%) as disjunct refugia habitat for at least one species under current conditions, but this was reduced to 20% and 7% with moderate (894 km) and warmest (313 km) climate change projections.

The intricate interplay among plant productivity and soil factors is a pivotal driver for sustaining the carbon sequestration capacity of coastal wetlands. Yet, it remains uncertain whether climate warming will reshape the cause-and-effect interactions between coastal plant productivity and soil factors. In this study, we combined a manipulative warming experiment with a convergent cross-mapping technique to quantify the causal relationships, which can be either unidirectional or bidirectional, between plants (gross primary productivity, GPP) and soil environment (e.g. soil temperature, moisture and salinity). Our findings revealed that warming amplified the interaction between GPP and soil salinity in the coastal wetland ecosystem. While soil temperature primarily drove this causal relationship in control plots, a more complex interaction emerged in warming plots: soil salinity not only directly influenced GPP but also indirectly affected it by altering soil temperature and moisture. Overall, warming increased the number of causal pathways linking GPP with soil environmental factors, such as the effect of soil salinity on GPP and the impacts of GPP on soil moisture. These findings provide experimental evidence of intensified plant–soil causality in coastal wetlands under climate warming.

Forest thinning and ground cover plant management play crucial roles in habitat enhancement, yet their effects on soil microbiota remain poorly understood. This study examines their impact on soil properties and bacterial communities in artifcial spruce forests (Picea asperata) within China’s Huangtuliang ecological corridor, a crucial habitat for giant pandas. Thinning signifcantly alters soil pH and total phosphorus (TP) levels, with minimal changes observed in total nitrogen (TN), microbial biomass carbon (MBC) and nitrogen (MBN). The combined effect of thinning and ground cover presence increases soil organic carbon (SOC) to 65.47 g/kg, contrasting with its absence. Thinning enhances the abundance of Proteobacteria, Acidobacteria and Chlorofexi while reducing Actinobacteria. Conversely, ground cover removal decreases Proteobacteria and Bacteroidetes but increases Chlorofexi, Verrucomicrobia and Rokubacteria. These changes lead to reduced bacterial community diversity, as indicated by a lower Shannon diversity index and distinct community composition differences demonstrated through beta-diversity analysis. Soil pH, TP and MBN are crucial in maintaining bacterial community structure, with pH and TP exhibiting the strongest correlations. Network analysis confrms the signifcant infuence of TP and pH on bacterial genera across various phyla. This study reveals the role of stochastic processes in highelevation, low-temperature ecological corridors (R² = 0.817), with thinning’s impact varying depending on the ground cover presence, thus enhancing effects post-removal by reducing dispersal limitation (migration rate, m = 0.96). These fndings highlight the ecological implications of habitat management in sensitive ecosystems and advance our understanding of microbial dynamics in critical habitats.

The decomposition of deadwood is a crucial process for the accumulation and sequestration of soil organic carbon (SOC) in forest ecosystems. However, the response of SOC to different decay classes of deadwood and the underlying mechanisms remain poorly understood. Here, we investigated the dynamics of SOC, soil properties, extracellular enzyme activities, and phospholipid fatty acid biomarkers across five decay classes (ranging from 1 to 5) of Masson pine (Pinus massoniana Lamb.) downed deadwood in a subtropical–temperate ecotone forest in Central China. Our results revealed a nonlinear response pattern of SOC along the deadwood decomposition gradient, with the maximum value at the decay class 4. Soil available nitrogen content, bacterial biomass, fungal biomass, the ratio of fungal-to-bacterial biomass, cellulase, activity and ligninase activity all increased with the intensification of deadwood decay, while soil pH decreased. The increase in SOC content was associated with a direct positive effect of bacteria and both direct and indirect positive effects of fungi by cellulose activity, but ligninase activity showed no significant relationship with SOC content. These findings suggest that cellulose and microbial biomass are key determinants of soil C formation and sequestration during deadwood decomposition. This study highlights the importance of the nonlinear response of SOC to deadwood decay, providing valuable insights for predicting future carbon-climate feedbacks.

Dioecious plants show sexual dimorphism in their phosphorus (P) availability responses. However, the understanding of sex-specific strategies for P utilization and acquisition under varying soil moisture levels remains unclear. Here, we assessed a range of root functional traits, soil P properties, total foliar P concentration ([P]) and leaf chemical P fractions—inorganic P ([Pi]), metabolite P ([PM]), lipid P ([PL]), nucleic acid P ([PN]) and residual P ([PR])—as well as other leaf functional traits in female and male trees under different soil moisture levels (25% for high and 7% for low). Our results showed that females had larger specific root length under well-watered conditions, resulting in greater root foraging capacity. This led to a 36.3% decrease in soil active [Pi] in the rhizosphere and a 66.9 % increase in total foliar [P], along with all five foliar chemical P fractions ([Pi], [PM], [PL], [PN] and [PR]) compared with males. However, males exhibited significantly higher photosynthetic P utilization efficiency than females. Especially under low soil moisture levels, males exhibited a significant reduction in soil active organic P, coupled with a large increase in the exudation of soil phosphatases and carboxylates. Furthermore, the proportion of [PM] in total foliar [P] was 42.0% higher in males than in females. Mantel and Spearman correlation analyses revealed distinct coordination and trade-offs between foliar P fraction allocation and below-ground P acquisition strategies between the two sexes. Leveraging these sex-specific strategies could enhance the resilience of dioecious populations in forest plantations facing climate-induced variability.

Drought can greatly impact the biodiversity of an ecosystem and play a crucial role in regulating its functioning. However, the specific mechanisms by which drought mediate the biodiversity effect (BE) on community biomass in above- and belowground through functional traits remain poorly understood. Here, we conducted a common garden experiment in a greenhouse, which included two plant species richness levels and two water addition levels, to analyze the effects of biodiversity on aboveground biomass (AGB), belowground biomass (BGB) and total biomass (TB), and to quantify the relationship between BEs and functional traits under drought conditions. Our analysis focused on partitioning BEs into above- and belowground complementarity effect (CE) and selection effect (SE) at the species level, which allowed us to better understand the impacts of biodiversity on community biomass and the underlying mechanisms. Our results showed that plant species richness stimulated AGB, BGB and TB through CEs. Drought decreased AGB, BGB and TB, simultaneously. In addition, the aboveground CE was positively associated with the variation in plant height. SEs in above- and belowground were negatively correlated with the community mean plant height and root length, respectively. Furthermore, drought weakened the aboveground CE by decreasing variation in plant height, resulting in a reduction in AGB and TB. Our findings demonstrate that the complementarity of species is an important regulator of community biomass in above- and belowground, the dynamics of biomass under environmental stress are associated with the response of sensitive compartments.

Biochar is a promising material for soil remediation. However, most studies testing the roles of biochar in soil remediation have considered the use of single types of biochar, and the role of biochar diversity, as well as its interaction with species diversity of plant communities, has rarely been considered. We hypothesize that biochar diversity can infuence the impacts of plant diversity on soil remediation. We grew grassland communities consisting of three or six plant species in cadmium (Cd)-contaminated soil mixed with one, two or four types of biochar, with no grassland community and no biochar addition as the controls. Without plant communities or with communities consisting of three species, total Cd was signifcantly lower in the soil mixed with four types of biochar than in the soil without biochar or mixed with one or two types of biochar. With communities consisting of six species, total Cd decreased with the increasing number of biochar types. Without biochar addition, soil total Cd was not infuenced by species richness, but with biochar addition, it was lower in the presence of communities with six species than in the absence of plant communities irrespective of how many types of biochar were added. Also, soil total Cd was lower in the presence of communities with six than with three plant species when two or four types of biochar were added. Our study indicates that increasing biochar diversity can promote the impact of plant diversity on remediating soil contaminated by heavy metals such as Cd.

The survival and reproduction of plants in a particular region are closely related to the local ecological niche. The use of species distribution models based on the ecological niche concept to predict potential distributions can effectively guide the protection of endangered plants, prevention and control of invasive plants, and plant introduction and ex-situ conservation. However, traditional methods and processes for predicting potential distributions of plants are tedious and complex, requiring the collection and processing of large amounts of data and the manual operation of multiple tools. Therefore, it is difficult to achieve large-scale prediction of the potential distributions of plants. To address these limitations, by collecting and organizing a large amount of basic data, occurrence records, and environmental data and integrating species distribution models and mapping techniques, a workflow to automatically predict the potential distributions of Chinese plants was established, thus the innovative work of predicting the potential distributions of 32 000 species of plants in China was completed. Furthermore, an online platform for predicting plant distributions in China based on visualization technology was developed, providing a basis for sharing the prediction results across a wide range of scientists and technologists. Users can quickly access information about the potential distributions of plants in China, providing a reference for the collection, preservation, and protection of plant resources. In addition, users can quickly predict the potential distribution of a certain plant in a certain region across China according to specific needs, thus providing technical support for biodiversity conservation.

Phytoplankton play an irreplaceable role as producers in maintaining lake ecosystems. Nevertheless, scant attention has been given to investigating the dispersion of phytoplankton communities and the factors influencing them across expansive areas. In this study, we present the results of a survey on the distribution of phytoplankton community and the effects of different driving factors in 11 lakes along Inner Mongolia in July–August 2020. Non-metric multidimensional scaling analysis and variance decomposition (VPA) were used to elucidate the distribution of phytoplankton communities and the response of drivers. A total of 169 species of phytoplankton from 8 phyla were detected. Both the abundance and diversity of phytoplankton in the Inner Mongolia lakes showed a trend of high in the east and low in the west (with Daihai Lake as the boundary). The Margalef index of phytoplankton significantly negatively correlated with salinity (r = −0.707, P < 0.05) and total dissolved solids (r = −0.720, P < 0.05), and both density and biomass highly significantly positively correlated with the suspended solids, Chlorophyll a and trophic level index. The VPA explained 38.9% of the changes in the phytoplankton community with the highest rate of explanation of land use. Therefore, preventing anthropogenic impacts, as well as reducing nutrient loads, can effectively ensure the ecological diversity of lake phytoplankton in lake populations with large geographical spans and varying levels of nutrients.

Plant roots show flexible traits to changing precipitation, but the factors driving root trait covariation remain poorly understood. This study investigated six key root traits and explored the potential driving factors, including plant community characteristics and soil properties, in the Zoige alpine meadow across five precipitation gradients: natural precipitation (1.0P), a 50% increasing precipitation (1.5P), and 30%, 50% and 90% decreasing precipitation (0.7P, 0.5P and 0.1P, respectively). Our results demonstrated distinct root trait responses to changes in precipitation. Both increasing (1.5P) and decreasing precipitation (0.1P, 0.5P and 0.7P) inhibited root diameter (RD), specific root length (SRL) and specific root area compared with 1.0P. Conversely, root tissue density and root nitrogen content increased under decreasing precipitation but declined under 1.5P. With increasing precipitation, root foraging strategies shifted with thinner RD and larger SRL to that with a larger diameter. Shifts in root strategies were primarily influenced by soil properties, specifically soil water content and available nitrogen. Additionally, root strategies in surface soils (0–10 cm) were mainly related to the grass and sedge coverage, whereas in deeper soils (10–20 cm) root strategies were related to overall plant community coverage and biomass. Our findings indicate that root trait variations and strategies in alpine meadows are co-driven by soil properties and plant communities in response to changing precipitation.

The protection and management of the wetland should consider the changes in hydrological connectivity (HC) caused by the structural modifications of the soil macropores. The main purpose of our work is to clarify and quantify the influence of the soil macropores volume on the vertical soil hydrodynamic process mechanically and statistically by taking the form of a case study in Yellow River Delta (YRD), and further reveal the vertical hydrological connectivity in this area. Based on X-ray computed tomography and constant head permeability test, the results showed a highly spatial heterogeneity of the soil structure in the YRD, hydraulic parameter (K_s) was negatively correlated with bulk density and positively with soil macropore volume, soil aeration and maximum water capacity. Using Hydrus 1-D software and the Green–Ampt model, we estimated the characteristics of the hydrodynamic process in the soil without macropores, then evaluated the effect of the soil macropore on soil hydrodynamic process by comparing the experimental results with the simulation results. We found that increasing soil microporosity improved the convenience of water movement, which would enhance the HC of the region. The results will further help to reveal the eco-hydrological process at a vertical scale in soil and provide a theoretical guide for wetland conservation and restoration.

Trade-offs have long been recognized as a crucial ecological strategy for plant species in response to environmental stresses and disturbances. However, it remains unclear whether trade-offs exist among different structures (or functions) of clonal plants in response to aeolian activities in sandy environments. We examined the growth (reproductive vs. vegetative), reproduction (sexual vs. asexual), and bud bank (tiller buds and rhizome buds, representing vertical and horizontal growth potential) characteristics of two dominant rhizomatous grasses (Psammochloa villosa and Phragmites australis) in the arid sand dunes of northwestern China. Our results showed that these two rhizomatous clonal species exhibited significant trade-offs in their adaptation strategies in response to changes in sand burial depth. Specifically, as sand burial depth increased, the clonal species tended to reduce their reproductive growth, sexual reproductive capacity, and horizontal growth potential, as evidenced by reductions in reproductive ramet number and proportion, panicles number, biomass, and their proportions, as well as rhizome bud number, biomass, and their proportions. Conversely, they increased vegetative growth, reproduction, and vertical growth potential, as evidenced by enhancements in vegetative ramet number and proportion, belowground bud number, biomass, and their proportions, and in tiller bud number, biomass, and their proportions. Our study underscores the importance of trade-offs in the adaptation strategies of rhizomatous clonal species in sandy environments where drought stress and aeolian disturbance coexist. Those trade-offs could ensure the population persistence and stability of pioneering psammophytes in sand dunes, which should be considered during sand-fixing and vegetation restoration efforts in arid sand dunes.

Plants adapt to the limitation of soil phosphorus (P) induced by nitrogen (N) deposition through a complex interaction of various root and leaf functional traits. In this study, a pot experiment was conducted to explore the effects of different levels of N addition (control, low N [LN]: 25 kg N ha⁻¹ yr⁻¹, high N [HN]: 50 kg N ha⁻¹ yr⁻¹) on tree growth, leaf nutrient content, foliar P fractions and root characteristics of two dominant tree species, the pioneer species Salix rehderiana Schneid and the climax species Abies fabri (Mast.) Craib, in a subalpine forest in southwestern China. The results demonstrated that LN addition had a minimal impact on leaf N and P contents. Conversely, HN addition significantly decreased the leaf P content in both species. Salix rehderiana exhibited more pronounced increases in specific root length and specific root area under P deficiency triggered by HN addition when compared with A. fabri. In contrast, A. fabri showed weaker morphological responses to N addition but had a higher proportion of foliar P to metabolic P, as well as higher root exudates rate and root phosphatase activity in response to HN addition. Abies fabri employs a synergistic approach by allocating a greater amount of leaf P to metabolite P and extracting P from the soil through P-mobilizing exudates and root phosphatase activity, while S. rehderiana exhibits higher flexibility in modifying its root morphology in response to P limitation induced by HN addition. This study provides insights into subalpine tree species adaptation to N-induced P limitation, emphasizing its significance for guiding forest management and conservation in the context of global climate change.

Global climate change poses a severe threat to mountain biodiversity. Phenotypic plasticity and local adaptation are two common strategies for alpine plant to cope with such change. They may facilitate organismal adaptation to contrasting environments, depending on the influences of the environment or genotype or their interacted effects. In this study, we use an endemic alpine plant (Rorippa elata) in the Hengduan mountains (HDM) to unravel its phenotypic basis of adaptation strategy and evaluate the relative contributions of environment and genotype to its phenotype. We transplanted 37 genotypes of R. elata into two common gardens across low and high elevations (2800 vs. 3800 m) during 2021–2022. Nine fitness-related traits were measured, including flowering probability and glucosinolates (GS) content. We estimated the environmental or genotypic contributions to the phenotype and identified the main environmental components. Our results revealed that both environment and genotype-by-environment interactions contributed to the phenotypes of R. elata. Latitudinal heterogeneity was identified as a key factor that explained 24% of the total phenotypic variation. In particular, genotypes of the northern HDM showed significantly higher plasticity in flowering probability than those of the southern HDM. Furthermore, within the southern HDM, GS content indicated local adaptation to herbivory stresses for R. elata genotypes along elevations. In conclusion, our results suggest that R. elata may have adapted to the alpine environment through species-level plasticity or regional-level local adaptation. These processes were shaped by either complex topography or interactions between genotype and mountain environments. Our study provides empirical evidence on the adaptation of alpine plants.

The dioecious plant, Hippophae rhamnoides, is a pioneer species in community succession on the Qinghai-Tibet Plateau (QTP), plays great roles in various ecosystem services. However, the males and females of the species differ both in their morphology and physiology, resulting in a change in the ratio of male to female plants depending on the environment. To further explore the functional traits critical to this sex-based distinctive response in the alpine grassland, we have surveyed the sex ratios, measured their photosynthetic parameters, height, leaf area and biomass allocation. The results showed that (i) The males had higher Pn, light saturation point, apparent quantum efficiency, A_max and lower water-use efficiency (WUE), which exhibited higher utilization efficiency or tolerance to strong light, while the females indicated higher utilization efficiency for low light and water. And it showed sex-specific biomass allocation patterns. (ii) H. rhamnoides populations across the successional stages all showed a male-biased sexual allocation, which was closely related to sex-specific WUE, Pn, root biomass/total biomass and root–crown ratio. (iii) The leaf traits of H. rhamnoides changed from higher N_area, P_area and leaf mass per area in the early and late to lower in the middle, which meant they moved their growth strategy from resource rapid acquisition to conservation as the succession progressed. (iv) The increasing soil total phosphorus mostly contributed to regulating the sex bias of populations and variations of traits during the succession. The results are vital for the management of grassland degradation and restoration due to shrub encroachment on the QTP.

Peatlands store one-third of the Earth’s carbon. Climate warming-induced peatlands vegetation shifted from Sphagnum to shrub, however, it is controversial whether this change leads to increased carbon losses. Through sequencing of the rhizosphere microbiome (vertically), measuring peat properties (vertically), a 35-day incubation experiment and a 35-day cross-inoculation experiment (only the upper layer), we investigated the ecosystem functions and the role of microbial communities and substrates in influencing the ecosystem functions of Sphagnum- and shrub-dominated peatlands in three locations in south China. The carbon dioxide (CO₂) emission from shrub-dominated peatlands was significantly lower than that from Sphagnum-dominated peatlands. The slow-growing fungi: Archaeorhizomyces, Hyphodiscus and Acidobacteria: Bryobacter, Occallatibacter were identified as keystone taxa in shrub-dominated peatlands, which mainly explained the effects of shrub microbial communities on CO₂ emission. The recalcitrant carbon content was the key substrate associated with CO₂ emission and the community composition of the plant rhizosphere microbiome. Furthermore, microbes fixed carbon in shrub-dominated peatlands was significantly higher than in Sphagnum-dominated peatlands, as the CO₂ emission reversed between Sphagnum- and shrub-dominated peatlands after soil sterilization. Overall, the relative abundance of keystone microbial taxa and nutrient levels decreased with peatland depth. Our study provided new evidence that climate change-induced peatland vegetation shift from Sphagnum to shrub leads to a higher accumulation of recalcitrant carbon, and does not deteriorate ecosystem functions. This study has implications for predicting the future influence of climate change on peatland ecosystems.

Plants produce secondary chemicals that may vary along with latitude due to changing abiotic and biotic stress gradients and local environmental conditions. Teasing apart the individual and combined effects of these different abiotic, such as soil nutrients, and biotic factors, such as soil biota and herbivores, on secondary chemicals is critical for understanding plant responses to changing environments. We conducted an experiment at different latitudes in China, using tallow tree (Triadica sebifera) seedlings sourced from a population at 31° N. These seedlings were cultivated in gardens located at low, middle and high latitudes, with either local soil or soil from the original seed collection site (origin soil). The seedlings were exposed to natural levels of aboveground herbivores or had them excluded. Plant secondary chemicals (both foliar and root), aboveground herbivores and soil characteristics were measured. Results showed that most leaf and root secondary metabolites depended on the interaction of the experimental site and soil type. Leaf and root phenolic and tannin concentrations were higher at the middle latitude site, especially in the origin soil. Root and foliar flavonoid concentrations increased when aboveground herbivores were excluded. Microbial communities depended strongly on soil treatment. The different responses of tannins versus flavonoids suggest that these two chemical classes differ in their responses to the varying abiotic and biotic factors in these sites along latitudes. Taken together, our results emphasize the importance of considering the interactive effects of local environmental conditions, soil properties and herbivoryin regulating plant chemical defenses.

Global climate change is expected to have a significant impact on ecosystems worldwide, especially for alpine meadows which are considered as one of the most vulnerable components. However, the effects of global warming on the plant nitrogen-phosphorus stoichiometry and resorption in alpine meadows remain unclear. Therefore, to investigate the plant nitrogen-phosphorus stoichiometry and resorption in alpine meadows on the Qinghai-Tibet Plateau, we conducted an artificial warming study using open-top chambers (OTCs) over the 3 years of warming period. We selected three dominant species, four height types of OTCs (0.4, 0.6, 0.8 and 1 m) and four warming methods (year-round warming, winter warming, summer-autumn-winter warming and spring- summer-autumn warming in the experiment) in this experiment. In our study, soil temperature significantly increased with increasing the height of OCTs under the different warming methods. Kobresia pygmaea presented an increase in nitrogen (N) limitation and Kobresia humilis presented an increase in phosphorus (P) limitation with increasing temperature, while Potentilla saundersiana was insensitive to temperature changes in terms of nitrogen and phosphorus limitations. Both nitrogen resorption efficiency:phosphorus resorption efficiency and N:P trends in response to rising temperatures were in the same direction. The differential responses of the chemical stoichiometry of the three species to warming were observed, reflecting that the responses of nitrogen and phosphorus limitations to warming are multifaceted, and the grassland ecosystems may exhibit a certain degree of self-regulatory capability. Our results show that using chemical dosage indicators of a single dominant species to represent the nitrogen and phosphorus limitations of the entire ecosystem is inaccurate, and using N:P to reflect the nutritional limitations might have been somewhat misjudged in the context of global warming.

An important challenge in ecology is to link functional traits to plant survival for generalizable predictions of plant demographical dynamics. However, whether root and leaf traits are consistently associated with tree survival remains uncertain because of the limited representation of root traits. Moreover, the relationships between plant traits and survival are rarely linear and are likely to vary with tree size. We analyzed demographic data from 17 901 trees of 32 subtropical tree species under 3-year-old monocultures to test whether root and leaf traits have consistent relationships with tree survival and how the relationships between traits and tree survival vary with tree diameter. We discovered that leaf and root traits have inconsistent effects on tree survival. Specifically, while specific leaf area (SLA; an acquisition strategy) showed a marginally significant negative impact on survival, root diameter (RD; a conservative trait within the one-dimensional root economic spectrum) also demonstrated a significant negative effect on survival. Furthermore, we found size-dependent relationships between traits and tree survival. The effect of SLA, leaf phosphorus concentration and specific root length, on survival shifted from negative to positive with increasing tree size. However, species with high leaf thickness and RD were positively linked to survival only for small trees. The results highlight that to accurately predict the relationships between traits and tree survival, it is essential to consider both above- and belowground traits, as well as the size-dependent relationships between traits and tree survival.

Alpine treelines are considered ecological monitors recording the impacts of climate change on trees and forests. To date, most treeline research has focused on how climate change drives treeline dynamics. However, little is known about how biotic interactions mediate treeline shifts, particularly in the case of tree recruitment, a bottleneck of treeline dynamics. We hypothesized that inter- and intraspecific facilitation determined the establishment and survival of tree seedlings at alpine treelines. To test this hypothesis, 630 Abies georgei var. smithii seedlings with different ages (4-6, 7-9 and 10-15 years old) were transplanted into three growth habitats (canopy-in, canopy-out and meadow) across the alpine treeline ecotone (4300-4500 m) in the Sygera Mountains, on the southeastern Qinghai-Tibetan Plateau. Microclimate, height growth, mortality rates and leaf functional traits of transplanted seedlings were measured over 3 years. We found that the variations in leaf functional traits were driven by microclimate. After the transplantation, the leaf concentrations of soluble sugars and starch and C:P ratio increased, whereas leaf size decreased. The resource use of seedlings gradually shifted to a more conservative strategy as indicated by changes in non-structural carbohydrates and nutrient concentrations. Radiation, temperature and moisture conditions, mediated by plant interactions, influenced seedling mortality and annual growth by affecting leaf morphological traits. Our findings illustrate how facilitation plays a crucial role in altering solar radiation and leaf trait functioning, determining seedling survival and growth at alpine treelines. We provide new insights into the underlying mechanisms for tree establishment and alpine treeline shifts in response to climate change.