Differential phenotypic plasticity of subalpine trees predicts trait integration under climate warming

Understanding limiting factors of phenotypic plasticity is essential given its critical role in shaping biological adaptation and evolution in changing environments. It has been proposed that the pattern of phenotypic correlation could constrain trait plasticity. However, the interplay between phenotypic plasticity and integration has remained contentious. We experimentally simulated climate warming in juveniles of three subalpine tree species by exposing them to three-year in situ open-top chambers (OTCs), and then measured functional plasticity of 72 eco-physiological traits to evaluate whether phenotypic integration constituted an intrinsic constraint to plasticity. We also tested the relationship between the differences in plasticity and maintenance in trait integration. Phenotypic plasticity was positively associated with integration in deciduous tree species under warming. The difference in the plasticity of two paired traits could predict their integration in different environments, where traits displaying more similar plasticity were more likely to be correlated. Our study showed no indication that phenotypic integration constrained plasticity. More importantly, we demonstrated that differential plasticity between traits might result in a notable reorganization of the trait associations, and that warming commonly induced a tighter phenotype. Our study provides new insights into the interplay between phenotypic plasticity and integration in subalpine trees under climate warming.

Friends because of foes: synchronous movement within predator-prey domains

For prey, movement synchrony represents a potent antipredator strategy. Prey, however, must balance the costs and benefits of using conspecifics to mediate risk. Thus, the emergent patterns of risk-driven sociality depend on variation in space and in the predators and prey themselves. We applied the concept of predator-prey habitat domain, the space in which animals acquire food resources, to test the conditions under which individuals synchronize their movements relative to predator and prey habitat domains. We tested the response of movement synchrony of prey to predator-prey domains in two populations of ungulates that vary in their gregariousness and predator community: (i) elk, which are preyed on by wolves; and (ii) caribou, which are preyed on by coyotes and black bears. Prey in both communities responded to cursorial predators by increasing synchrony during seasons of greater predation pressure. Elk moved more synchronously in the wolf habitat domain during winter and caribou moved more synchronously in the coyote habitat domains during spring. In the winter, caribou increased movement synchrony when coyote and caribou domains overlapped. By integrating habitat domains with movement ecology, we provide a compelling argument for social behaviours and collective movement as an antipredator response. This article is part of the theme issue 'The spatial-social interface: A theoretical and empirical integration'.

An integrated fast-slow plant and nematode economics spectrum predicts soil organic carbon dynamics during natural restoration

Aboveground and belowground attributes of terrestrial ecosystems interact to shape carbon (C) cycling. However, plants and soil organisms are usually studied separately, leading to a knowledge gap regarding their coordinated contributions to ecosystem C cycling. We explored whether integrated consideration of plant and nematode traits better explained soil organic C (SOC) dynamics than plant or nematode traits considered separately. Our study system was a space-for-time natural restoration chronosequence following agricultural abandonment in a subtropical region, with pioneer, early, mid and climax stages. We identified an integrated fast-slow trait spectrum encompassing plants and nematodes, demonstrating coordinated shifts from fast strategies in the pioneer stage to slow strategies in the climax stage, corresponding to enhanced SOC dynamics. Joint consideration of plant and nematode traits explained more variation in SOC than by either group alone. Structural equation modeling revealed that the integrated fast-slow trait spectrum influenced SOC through its regulation of microbial traits, including microbial C use efficiency and microbial biomass. Our findings confirm the pivotal role of plant-nematode trait coordination in modulating ecosystem C cycling and highlight the value of incorporating belowground traits into biogeochemical cycling under global change scenarios.

Naturalized species drive functional trait shifts in plant communities

Despite decades of research documenting the consequences of naturalized and invasive plant species on ecosystem functions, our understanding of the functional underpinnings of these changes remains rudimentary. This is partially due to ineffective scaling of trait differences between native and naturalized species to whole plant communities. Working with data from over 75,000 plots and over 5,500 species from across the United States, we show that changes in the functional composition of communities associated with increasing abundance of naturalized species mirror the differences in traits between native and naturalized plants. We find that communities with greater abundance of naturalized species are more resource acquisitive aboveground and belowground, shorter, more shallowly rooted, and increasingly aligned with an independent strategy for belowground resource acquisition via thin fine roots with high specific root length. We observe shifts toward herbaceous-dominated communities but shifts within both woody and herbaceous functional groups follow community-level patterns for most traits. Patterns are remarkably similar across desert, grassland, and forest ecosystems. Our results demonstrate that the establishment and spread of naturalized species, likely in combination with underlying environmental shifts, leads to predictable and consistent changes in community-level traits that can alter ecosystem functions.

Refocusing the microbial rare biosphere concept through a functional lens

The influential concept of the rare biosphere in microbial ecology has underscored the importance of taxa occurring at low abundances yet potentially playing key roles in communities and ecosystems. Here, we refocus the concept of rare biosphere through a functional trait-based lens and provide a framework to characterize microbial functional rarity, a combination of numerical scarcity across space or time and trait distinctiveness. We demonstrate how this novel interpretation of the rare biosphere, rooted in microbial functions, can enhance our mechanistic understanding of microbial community structure. It also sheds light on functionally distinct microbes, directing conservation efforts towards taxa harboring rare yet ecologically crucial functions.

Root and biomass allocation traits predict changes in plant species and communities over four decades of global change

Global change is affecting the distribution and population dynamics of plant species across the planet, leading to trends such as shifts in distribution toward the poles and to higher elevations. Yet, we poorly understand why individual species respond differently to warming and other environmental changes, or how the trait composition of communities responds. Here we ask two questions regarding plant species and community changes over 42 years of global change in a temperate montane forest in Québec, Canada: (1) How did the trait composition, alpha diversity, and beta diversity of understory vascular plant communities change between 1970 and 2010, a period over which the region experienced 1.5°C of warming and changes in nitrogen deposition? (2) Can traits predict shifts in species elevation and abundance over this time period? For 46 understory vascular species, we locally measured six aboveground traits, and for 36 of those (not including shrubs), we also measured five belowground traits. Collectively, they capture leading dimensions of phenotypic variation that are associated with climatic and resource niches. At the community level, the trait composition of high-elevation plots shifted, primarily for two root traits: specific root length decreased and rooting depth increased. The mean trait values of high-elevation plots shifted over time toward values initially associated with low-elevation plots. These changes led to trait homogenization across elevations. The community-level shifts in traits mirrored the taxonomic shifts reported elsewhere for this site. At the species level, two of the three traits predicting changes in species elevation and abundance were belowground traits (low mycorrhizal fraction and shallow rooting). These findings highlight the importance of root traits, which, along with leaf mass fraction, were associated with shifts in distribution and abundance over four decades. Community-level trait changes were largely similar across the elevational and temporal gradients. In contrast, traits typically associated with lower elevations at the community level did not predict differences among species in their shift in abundance or distribution, indicating a decoupling between species- and community-level responses. Overall, changes were consistent with some influence of both climate warming and increased nitrogen availability.

Response of Seed Germination and Seedling Growth of Six Desert Shrubs to Different Moisture Levels under Greenhouse Conditions

Moisture is the most important environmental factor limiting seed regeneration of shrubs in desert areas. Therefore, understanding the effects of moisture changes on seed germination, morphological and physiological traits of shrubs is essential for vegetation restoration in desert areas. In March to June 2023, in a greenhouse using the potting method, we tested the effects of soil moisture changes (5%, 10%, 15%, 20% and 25%) on seed germination and seedling growth of six desert shrubs (Zygophyllum xanthoxylum, Nitraria sibirica, Calligonum mongolicum, Corethrodendron scoparium, Caragana korshinskii, and Corethrodendron fruticosu). Results showed that (1) seed germination percent and vigor index were significantly higher at 15 and 20% soil moisture content than at 5 and 10%; (2) shoot length, primary root length, specific leaf area and biomass of seedlings were significantly higher in the 15% and 20% soil moisture content treatments than in the 5% and 10% treatments; (3) superoxide dismutase activity (SOD) and soluble protein content (SP) decreased with decreasing soil water content, while peroxidase activity (POD) and catalase activity (CAT) showed a decreasing and then increasing trend with increasing soil water content; (4) the six seeds and seedling of shrubs were ranked in order of their survivability in response to changes in soil moisture: Caragana korshinskii > Zygophyllum xanthoxylum > Calligonum mongolicum > Corethrodendron scoparium > Corethrodendron fruticosu > Nitraria sibirica. Our study shows that shrub seedlings respond to water changes by regulating morphological and physiological traits together. More importantly, we found that C. korshinskii, Z. xanthoxylum and C. mongolicum were more survivable when coping with water deficit or extreme precipitation. The results of the study may provide a reference for the selection and cultivation of similar shrubs in desert areas under frequent extreme droughts in the future.

Soil microbial influences over coexistence potential in multispecies plant communities in a subtropical forest

Soil microbes have long been recognized to substantially affect the coexistence of pairwise plant species across terrestrial ecosystems. However, projecting their impacts on the coexistence of multispecies plant systems remains a pressing challenge. To address this challenge, we conducted a greenhouse experiment with 540 seedlings of five tree species in a subtropical forest in China and evaluated microbial effects on multispecies coexistence using the structural method, which quantifies how the structure of species interactions influences the likelihood for multiple species to persist. Specifically, we grew seedlings alone or with competitors in different microbial contexts and fitted individual biomass to a population dynamic model to calculate intra- and interspecific interaction strength with and without soil microbes. We then used these interaction structures to calculate two metrics of multispecies coexistence, structural niche differences (which promote coexistence) and structural fitness differences (which drive exclusion), for all possible communities comprising two to five plant species. We found that soil microbes generally increased both the structural niche and fitness differences across all communities, with a much stronger effect on structural fitness differences. A further examination of functional traits between plant species pairs found that trait differences are stronger predictors of structural niche differences than of structural fitness differences, and that soil microbes have the potential to change trait-mediated plant interactions. Our findings underscore that soil microbes strongly influence the coexistence of multispecies plant systems, and also add to the experimental evidence that the influence is more on fitness differences rather than on niche differences.

An appreciation of apex-to-base variation in xylem traits will lead to more precise understanding of xylem phenotypic plasticity

Xylem air embolism is the primary cause of drought-related tree mortality. Phenotypic plasticity of xylem traits is key for species acclimation to environmental variability and evolution. It is widely believed that plants increase xylem embolism resistance in response to drought. However, I argue that this hypothesis, based on extensive literature, relies on sampling methods that overlook predictable anatomical patterns, potentially biasing our understanding of acclimation and adaptation strategies.

Evolutionarily conserved core microbiota as an extended trait in nitrogen acquisition strategy of herbaceous species

Microbiota have co-evolved with plants over millions of years and are intimately linked to plants, ranging from symbiosis to pathogenesis. However, our understanding of the existence of a shared core microbiota across phylogenetically diverse plants remains limited. A common garden field experiment was conducted to investigate the rhizosphere microbial communities of phylogenetically contrasting herbaceous families. Through a combination of metagenomic sequencing, analysis of plant economic traits, and soil biochemical properties, we aimed to elucidate the eco-evolutionary role of the core rhizosphere microbiota in light of plant economic strategies. We identified a conserved core microbiota consisting of 278 taxa that was closely associated with the phylogeny of the plants studied. This core microbiota actively participated in multiple nitrogen metabolic processes and showed a strong correlation with the functional potential of rhizosphere nitrogen cycling, thereby serving as an extended trait in the plant nitrogen acquisition. Furthermore, our examination of simulated species loss revealed the crucial role of the core microbiota in maintaining the rhizosphere community's network stability. Our study highlighted that the core microbiota, which exhibited a phylogenetically conserved association with plants, potentially represented an extension of the plant phenotype and played an important role in nitrogen acquisition. These findings held implications for the utilization of microbiota-mediated plant functions.

Unveiling Arthropod Responses to Climate Change: A Functional Trait Analysis in Intensive Pastures

This study investigates the impact of elevated temperatures on arthropod communities in intensively managed pastures on the volcanic island of Terceira, Azores (Portugal), using a functional trait approach. Open Top Chambers (OTCs) were employed to simulate increased temperatures, and the functional traits of ground dwelling arthropods were analyzed along a small elevation gradient (180-400 m) during winter and summer. Key findings include lower abundances of herbivores, coprophagous organisms, detritivores, and fungivores at high elevations in summer, with predators showing a peak at middle elevations. Larger-bodied arthropods were more prevalent at higher elevations during winter, while beetles exhibited distinct ecological traits, with larger species peaking at middle elevations. The OTCs significantly affected the arthropod communities, increasing the abundance of herbivores, predators, coprophagous organisms, and fungivores during winter by alleviating environmental stressors. Notably, iridescent beetles decreased with elevation and were more common inside OTCs at lower elevations, suggesting a thermoregulatory advantage. The study underscores the importance of considering functional traits in assessing the impacts of climate change on arthropod communities and highlights the complex, species-specific nature of their responses to environmental changes.

Closely related species differ in their traits, but competition induces high intra-specific variability

Theories explaining community assembly assume that biotic and abiotic filters sort species into communities based on the values of their traits and are thus based on between-species trait variability (BTV). Nevertheless, these filters act on individuals rather than on species. Consequently, the selection is also influenced by intraspecific trait variability (ITV) and its drivers. These drivers may be abiotic (e.g., water availability) or biotic (e.g., competition). Although closely related species should have similar traits, many of them coexist. We investigated the relative magnitudes of BTV and ITV in coexisting closely related species and how their individual traits differ under different drivers of ITV. We manipulated conditions in a greenhouse pot experiment with four common Carex species, where individuals of each species originated from four source localities. Individuals were grown in factorial combinations of two moisture levels, with and without a competitor (grass species Holcus lanatus, a frequent competitor). We analyzed the variability of six morphological traits on individuals in the greenhouse and three morphological traits in the source localities. Species identity was the main determinant of differences in most traits. Competition exerted a greater effect than water availability. For leaf dry matter content (LDMC) and vegetative height, competition's effect even exceeded the variability among species. On the contrary, for specific leaf area (SLA) and clonal spread, the interspecific differences exceeded ITV induced by experimental treatments. SLA measured in the greenhouse closely correlated with values measured in field populations, while LDMC did not. The variability caused by source locality of ramets in the greenhouse was small, although sometimes significant. Closely related species differ in their traits, but for some traits, ITV can exceed BTV. We can expect that ITV can modify the processes of community assembly, particularly among coexisting closely related species.

Drought tolerance and species abundance mediate dry season negative density dependence in a tropical forest

Conspecific negative density dependence (CNDD) is thought to be a key process in maintaining plant diversity. However, the strength of CNDD is highly variable in space and time as well as among species, and correlates of this variation that might help to understand and explain it remain largely unquantified. Using Bayesian hierarchical models, we took advantage of 10-year seedling monitoring data that were collected annually in every dry and rainy season in a seasonal tropical forest. We quantified the interspecific variation in the strength of CNDD and its temporal variation. We also examined potential correlates of this interspecific and temporal variation, including species functional traits (such as drought-tolerant traits, defense-related traits, and recourse acquisition traits) and species abundances. In the dry season, we found a negative relationship between the density of neighboring conspecific seedlings on seedling survival, while in the rainy season, there was a negative relationship between the density of neighboring conspecific adults on seedling survival. In addition, we found that interspecific variation in CNDD was related to drought-tolerant traits in the dry season but not in the rainy season. Across years, we found that drought-intolerant species suffer less CNDD during the dry seasons that have higher rainfall, whereas drought-tolerant species suffer less CNDD when the dry season has lower rainfall. We also found that rare species suffered stronger CNDD in the dry season. Overall, our study highlights that CNDD is highly variable among species and through time, necessitating a deeper appreciation of the environmental and functional contexts of CNDD and their interactions.

Nitrogen enrichment enhances the negative top-down effect on plant functional traits

Eutrophication resulting from anthropogenic activities has been recognized as a significant driver of changes in ecosystem functioning. Furthermore, it may exacerbate the top-down effect and thus exert an important impact on plant growth. To test this hypothesis, we conducted a 3-year manipulative field experiment to investigate the impacts of nitrogen addition and crab herbivory on the growth of Phragmites australis in the salt marsh of the Yellow River Delta. The results demonstrated that a 3-year nitrogen addition can significantly increase the total nitrogen and carbon content of P. australis leaves, thereby enhancing their nutritional value and palatability, as well as increasing the proportion of leaves consumed by crabs. Therefore, nitrogen addition together with crab herbivory had a significant negative effect on P. australis height, leaf length, and leaf breadth in the ambient crab and procedural crab cage treatment compared to the crab exclusion treatment. The structural equation modeling further substantiated these findings. The model revealed a direct and positive correlation between nitrogen addition and leaf nutrient content (path coefficient = 0.34). Additionally, it demonstrated a direct and positive relationship between leaf nutrient content and the proportion of leaves consumed by crabs (path coefficient = 0.22). Simultaneously, there was an observed negative correlation (path coefficient = - 0.37) between the proportion of leaves consumed by crabs and plant functional traits, represented by leaf length in the model, during 2018. Moreover, the crab exclusion treatment significantly reduced the proportion of leaves consumed by crabs and thus enhanced the P. australis individuals, leaf number, and biomass. Overall, crab herbivory had a significant detrimental top-down effect on the growth of P. australis, and nitrogen enrichment may exacerbate this top-down effect. The findings of our study highlight the combined adverse effects of nutrient enrichment and top-down on plant functional traits and plant growth. The findings of this study will contribute to a comprehensive understanding of the underlying factors influencing vegetation degradation in coastal wetland, thereby establishing a solid theoretical framework for the conservation and management of wetland ecosystems within the context of global environmental change.

Influence of Functional Traits of Dominant Species of Different Life Forms and Plant Communities on Ecological Stoichiometric Traits in Karst Landscapes

Assessing the functional traits and ecological stoichiometric characteristics of dominant species across different life forms within plant communities in karst environments and investigating the inherent connection between them can provide insights into how species adjust their functional attributes in response to habitat heterogeneity. This approach offers a more comprehensive understanding of ecosystem processes and functions in contrast to examination of the taxonomic diversity of species. This study examines the relationship between the functional characteristics of dominant species in plant communities of various life forms in karst environments, focusing on deciduous leaf-soil ecological stoichiometry. The investigation relies on community science surveys, as well as the determination and calculation of plant functional traits and ecological stoichiometries, in plant communities of various life forms in Guizhou (a province of China). The findings of our study revealed considerable variability in the functional trait characteristics of dominant species across different plant-community life forms. Specifically, strong positive correlations were observed among plant height (PLH), leaf area (LA), leaf dry matter content (LDMC), and specific leaf area (SLA) in the dominant species. Additionally, our results indicated no significant differences in leaf ecological stoichiometry among different life forms. However, we did observe significant differences and strong positive correlations between soil N:P, withered material C:N, and apomictic C:P. Furthermore, our study found that plant height (PLH), leaf area (LA), and specific leaf area (SLA) were particularly sensitive to the ecological stoichiometry of soil and apomixis. The results of our study suggest that the functional traits of diverse plant-community life forms in karst regions are capable of adapting to environmental changes through various expressions and survival strategies. The development of various plant-community life forms in karst areas is particularly vulnerable to phosphorus limitation, and the potential for litter decomposition and soil nutrient mineralization is comparatively weaker. The functional traits of various plant-community life forms in karst regions exhibit greater sensitivity to both the soil's C:N ratio and the C:N ratio of apomictic material. Habitat variations may influence the ecological stoichiometric characteristics of the plant leaf-apomictic soil continuum.

Divergent structural leaf trait spectra in succulent versus non-succulent plant taxa

BACKGROUND AND SCOPE

Plant functional traits are the result of natural selection to optimize carbon gain, leading to a broad spectrum of traits across environmental gradients. Among plant traits, leaf water storage capacity is paramount for plant drought resistance. We explored whether leaf-succulent taxa follow trait correlations similar to those of non-leaf-succulent taxa to evaluate whether both are similarly constrained by relationships between leaf water storage and climate.

METHODS

We tested the relationships among three leaf traits related to water storage capacity and resource use strategies in 132 species comprising three primary leaf types: succulent, sclerophyllous, and leaves with rapid returns on water investment, referred to as fast return. Correlation coefficients among specific leaf area (SLA), water mass per unit of area (WMA), and saturated water content (SWC) were tested, along with relationships between leaf trait spectra and aridity determined from species occurrence records.

RESULTS

Both SWC and WMA at a given SLA were ~10-fold higher in succulent leaves than in non-succulent leaves. While SWC actually increased with SLA in non-succulent leaves, no relationship was detected between SWC and SLA in succulent leaves, although WMA decreased with SLA in all leaf types. A principal component analysis (PCA) revealed that succulent taxa occupied a widely different mean trait space than either fast-return (P < 0.0001) or sclerophyllous (P < 0.0001) taxa along the first PCA axis, which explained 63 % of mean trait expression among species. However, aridity only explained 12 % of the variation in PCA1 values. This study is among the first to establish a structural leaf trait spectrum in succulent leaf taxa and quantify contrasts in leaf water storage among leaf types relative to specific leaf area.

CONCLUSIONS

Trait coordination in succulent leaf taxa may not follow patterns similar to those of widely studied non-succulent taxa.

Comparing the Environmental Influences and Community Assembly of Protist Communities in Two Anthropogenic Coastal Areas

Anthropogenic stresses are intensively affecting the structure and function of microbial communities in coastal ecosystems. Despite being essential components of coastal ecosystems, the environmental influences and assembly processes of protist communities remain largely unknown in areas with severe disturbance. Here, we used 18S rRNA gene high-throughput sequencing to compare the composition, assembly process, and functional structure of the protist communities from the coastal areas of the Northern Yellow Sea (NYS) and the Eastern Bohai Sea (EBS). These two areas are separated by the Liaodong Peninsula and experience different anthropogenic stresses due to varying degrees of urbanization. We detected significant differences between the protist communities of the two areas. Environmental and geographic factors both influenced the composition of protist communities, with environmental factors playing a greater role. The neutral community model indicated that the assembly of protist communities was governed by deterministic processes, with stochastic processes having a stronger influence in the EBS area compared to the NYS area. The phototrophic and consumer communities, influenced by different environmental factors, differed significantly between the two areas. Our results provide insights into the biogeography and assembly of protist communities in estuaries under anthropogenic stresses, which may inform future coastal management.

How does climate change impact social bees and bee sociality?

Climatic factors are known to shape the expression of social behaviours. Likewise, variation in social behaviour can dictate climate responses. Understanding interactions between climate and sociality is crucial for forecasting vulnerability and resilience to climate change across animal taxa. These interactions are particularly relevant for taxa like bees that exhibit a broad diversity of social states. An emerging body of literature aims to quantify bee responses to environmental change with respect to variation in key functional traits, including sociality. Additionally, decades of research on environmental drivers of social evolution may prove fruitful for predicting shifts in the costs and benefits of social strategies under climate change. In this review, we explore these findings to ask two interconnected questions: (a) how does sociality mediate vulnerability to climate change, and (b) how might climate change impact social organisation in bees? We highlight traits that intersect with bee sociality that may confer resilience to climate change (e.g. extended activity periods, diet breadth, behavioural thermoregulation) and we generate predictions about the impacts of climate change on the expression and distribution of social phenotypes in bees. The social evolutionary consequences of climate change will be complex and heterogeneous, depending on such factors as local climate and plasticity of social traits. Many contexts will see an increase in the frequency of eusocial nesting as warming temperatures accelerate development and expand the temporal window for rearing a worker brood. More broadly, climate-mediated shifts in the abiotic and biotic selective environments will alter the costs and benefits of social living in different contexts, with cascading impacts at the population, community and ecosystem levels.

Brandt's vole (Lasiopodomys brandtii) affects the dominant position of three gramineous species by altering defense traits and interspecific competition

Rodents can cause considerable changes in plant community composition. However, relationships between shifts in species dominance and plant functional traits caused by rodents have seldom been investigated, especially for belowground functional traits. In this study, a set of enclosures was constructed to analyze the effects of 10 years of Brandt's voles' activities on the defense strategies and dominant position changes of three gramineous plants (Leymus chinensis, Stipa krylovii, and Cleistogenes squarrosa) in Inner Mongolia. Here, we measured the dominance, biomass, and fourteen functional traits of three plants. The effects of Brandt's voles on dominance, biomass, and functional traits were analyzed, and then we explored the effect of functional traits on plant dominance by using the structural equation model. Results showed that long-term feeding by Brandt's voles resulted in a significant decrease in the dominance of L. chinensis and S. krylovii, whereas C. squarrosa was positively affected. The belowground biomass of L. chinensis and S. krylovii was higher in the vole treatment, which showed that they were increasing their escape characteristics. The leaf thickness of L. chinensis and the leaf C:N ratio of S. krylovii significantly increased, while the specific leaf area of C. squarrosa significantly decreased. All three gramineous showed increased resistance traits in response to Brandt's voles, which positively affected their dominance. Tolerance-related traits of S. krylovii significantly increased, with the increasing growth rate of root length contributing to enhancing its dominance. We highlight that selective feeding by rodents led to the selection of different defense strategies by three gramineous plants, and that changes in biomass allocation and functional traits in the different species affected plant dominance, driving changes in the plant communities.

Plant traits regulated metal(loid)s in dominant herbs in an antimony mining area of the karst zone, China

Understanding how plant functional traits respond to mining activities and impact metal(loid)s accumulation in dominant species is crucial for exploring the driving mechanisms behind plant community succession and predicting the ecological restoration potential of these plants. In this study, we investigated four dominant herbaceous species (Artemisia argyi, Miscanthus sinensis, Ficus tikoua, and Ageratina adenophora) growing on antimony (Sb) mining sites (MS) with high Sb and arsenic (As) levels, as well as non-mining sites (NMS). The aim was to analyze the variations in functional traits and their contribution to Sb and As concentrations in plants. Our results indicate that mining activities enhanced soil nitrogen (N) limitation and phosphorus (P) enrichment, while significantly reducing the plant height of three species, except for F. tikoua. The four species absorbed more calcium (Ca) to ensure higher tolerance to Sb and As levels, which is related to the activation of Ca signaling pathways and defense mechanisms. Furthermore, plant Sb and As concentrations were dependent on soil metal(loid) levels and plant element stoichiometry. Overall, these findings highlight the regulatory role of plant element traits in metal(loid) concentrations, warranting widespread attention and further study in the future.

Leaf and twig traits predict habitat adaptation and demographic strategies in tropical freshwater swamp forest trees

Differences in demographic and environmental niches facilitate plant species coexistence in tropical forests. However, the adaptations that enable species to achieve higher demographic rates (e.g. growth or survival) or occupy unique environmental niches (e.g. waterlogged conditions) remain poorly understood. Anatomical traits may better predict plant environmental and demographic strategies because they are direct measurements of structures involved in these adaptations. We collected 18 leaf and twig traits from 29 tree species in a tropical freshwater swamp forest in Singapore. We estimated demographic parameters of the 29 species from growth and survival models, and degree of association toward swamp habitats. We examined pairwise trait-trait, trait-demography and trait-environment links while controlling for phylogeny. Leaf and twig anatomical traits were better predictors of all demographic parameters than other commonly measured leaf and wood traits. Plants with wider vessels had faster growth rates but lower survival rates. Leaf and spongy mesophyll thickness predicted swamp association. These findings demonstrate the utility of anatomical traits as indicators of plant hydraulic strategies and their links to growth-mortality trade-offs and waterlogging stress tolerance that underlie species coexistence mechanisms in tropical forest trees.

Resurrecting Historical Observations to Characterize Species-Specific Nesting Traits of Bumblebees

AbstractIn recent years, ecological research has become increasingly synthetic, relying on revolutionary changes in data availability and accessibility. In spite of their strengths, these approaches may cause us to overlook natural history knowledge that is not part of the digitized English-language scientific record. Here, we combine historic and modern documents to quantify species-specific nesting habitat associations of bumblebees (Bombus spp. Latreille, 1802 Apidae). We compiled nest location data from 316 documents, of which 81 were non-English and 93 were published before 1950. We tested whether nesting traits show phylogenetic signal, examined relationships between habitat associations at different scales, and compared methodologies used to locate nests. We found no clear phylogenetic signals, but we found that nesting habitat associations were somewhat generalizable within subgenera. Landcover associations were related to nesting substrate associations; for example, surface-nesting species also tended to be associated with grasslands. Methodology was associated with nest locations; community scientists were most likely and researchers using nest boxes were least likely to report nests in human-dominated environments. These patterns were not apparent in past syntheses based only on the modern digital record. Our findings highlight the tremendous value of historic accounts for quantifying species' traits and other basic biological knowledge needed to interpret global-scale patterns.

Context specific effects of substrate composition on the taxonomic and functional diversity of macroinvertebrate communities in temperate lowland streams

Substrate composition has been widely recognised as a primary variable shaping lotic macroinvertebrate communities at the habitat unit level. However, fundamental understanding of how communities inhabiting mineralogical habitats (i.e., gravel, sand and silt) are structured across differing rivers is lacking. Moreover, research largely focusses on gravel beds and fine sediment in general (<2 mm) and as a result detailed field observations specifically of the sand and silt fractions are lacking. Using data from five UK streams collated from published studies, we assess taxonomic and functional biodiversity (alpha and beta diversity) at the habitat unit level (as defined by substrate composition of sand, silt and gravel). We found that the composition of taxonomic communities were clearly different in all habitat units for each individual stream (and at the landscape scale), with comparable, but less strong, distinctions between substrates for functional macroinvertebrate community composition. However, alpha diversity metrics and Local Contribution to Beta Diversity (LCBD) recorded among the different habitat units varied significantly across individual rivers, and the amount of variation explained by the habitat unit for taxonomic and functional composition demonstrated considerable differences suggesting strong context dependence. The depositional fine sediment habitats of sand and silt were found to support a discrete community composition and differing levels of alpha and beta diversity within and between rivers. We advocate that care should be taken when seeking to generalise biodiversity patterns at a landscape scale as our study highlights the high degree of context dependency when considering the role of the habitat template. Moreover, our results provide evidence that discriminating between the size fractions of fine sediment habitats (sand or silt) is important to fully elucidate the wider ecological importance of these habitats and the distinct taxonomic and functional biodiversity they support.

Genome size variation in Cape schoenoid sedges (Schoeneae) and its ecophysiological consequences

PREMISE

Increases in genome size in plants-often associated with larger, low-density stomata and greater water-use efficiency (WUE)-could affect plant ecophysiological and hydraulic function. Variation in plant genome size is often due to polyploidy, having occurred repeatedly in the austral sedge genus Schoenus in the Cape Floristic Region (CFR), while species in the other major schoenoid genus in the region, Tetraria, have smaller genomes. Comparing these genera is useful as they co-occur at the landscape level, under broadly similar bioclimatic conditions. We hypothesized that CFR Schoenus have greater WUE, with lower maximum stomatal conductance (gwmax) imposed by larger, less-dense stomata.

METHODS

We investigated relationships between genome size and stomatal parameters in a phylogenetic context, reconstructing a phylogeny of CFR-occurring Schoeneae (Cyperaceae). Species' stomatal and functional traits were measured from field-collected and herbarium specimens. Carbon stable isotopes were used as an index of WUE. Genome size was derived from flow-cytometric measurements of leafy shoots.

RESULTS

Evolutionary regressions demonstrated that stomatal size and density covary with genome size, positively and negatively, respectively, with genome size explaining 72-75% of the variation in stomatal size. Larger-genomed species had lower gwmax and C:N ratios, particularly in culms.

CONCLUSIONS

We interpret differences in vegetative physiology between the genera as evidence of more-conservative strategies in CFR Schoenus compared to the more-acquisitive Tetraria. Because Schoenus have smaller, reduced leaves, they likely rely more on culm photosynthesis than Tetraria. Across the CFR Schoeneae, ecophysiology correlates with genome size, but confounding sources of trait variation limit inferences about causal relationships between traits.

Biodiversity in changing environments: An external-driver internal-topology framework to guide intervention

Accompanying the climate crisis is the more enigmatic biodiversity crisis. Rapid reorganization of biodiversity due to global environmental change has defied prediction and tested the basic tenets of conservation and restoration. Conceptual and practical innovation is needed to support decision making in the face of these unprecedented shifts. Critical questions include: How can we generalize biodiversity change at the community level? When are systems able to reorganize and maintain integrity, and when does abiotic change result in collapse or restructuring? How does this understanding provide a template to guide when and how to intervene in conservation and restoration? To this end, we frame changes in community organization as the modulation of external abiotic drivers on the internal topology of species interactions, using plant-plant interactions in terrestrial communities as a starting point. We then explore how this framing can help translate available data on species abundance and trait distributions to corresponding decisions in management. Given the expectation that community response and reorganization are highly complex, the external-driver internal-topology (EDIT) framework offers a way to capture general patterns of biodiversity that can help guide resilience and adaptation in changing environments.