Leaf Economic Traits Research Articles

Leaf Photosynthetic and Functional Traits of Grassland Dominant Species in Response to Nutrient Addition on the Chinese Loess Plateau

Leaf photosynthetic and functional traits of dominant species are important for understanding grassland community dynamics under imbalanced nitrogen (N) and phosphorus (P) inputs. Here, the effects of N (N0, N50, and N100, corresponding to 0, 50, and 100 kg ha-1 yr-1, respectively) or/and P additions (P0, P40, and P80, corresponding to 0, 40, and 80 kg ha-1 yr-1) on photosynthetic characteristics and leaf economic traits of three dominant species (two grasses: Bothriochloa ischaemum and Stipa bungeana; a leguminous subshrub: Lespedeza davurica) were investigated in a semiarid grassland community on the Loess Plateau of China. Results showed that, after a three-year N addition, all three species had higher specific leaf area (SLA), leaf chlorophyll content (SPAD value), maximum net photosynthetic rate (PNmax), and leaf instantaneous water use efficiency (WUE), while also having a lower leaf dry matter content (LDMC). The two grasses, B. ischaemum and S. bungeana, showed greater increases in PNmax and SLA than the subshrub L. davurica. P addition alone had no noticeable effect on the PNmax of the two grasses while it significantly increased the PNmax of L. davurica. There was an evident synergetic effect of the addition of N and P combined on photosynthetic traits and most leaf economic traits in the three species. All species had relatively high PNmax and SLA under the addition of N50 combined with P40. Overall, this study suggests that N and P addition shifted leaf economic traits towards a greater light harvesting ability and, thus, elevated photosynthesis in the three dominant species of a semiarid grassland community, and this was achieved by species-specific responses in leaf functional traits. These results may provide insights into grassland restoration and the assessment of community development in the context of atmospheric N deposition and intensive agricultural fertilization.

Size- and environment-driven seedling survival and growth are mediated by leaf functional traits.

Ecologists usually find that plant demography (e.g. survival and growth) changes along with plant size and environmental gradients, which suggests the effects of ontogeny-related processes and abiotic filtering. However, the role of functional traits underlying the size– and environment–demography relationships is usually overlooked. By measuring individual-level leaf traits of more than 2700 seedlings in a temperate forest, we evaluated how seedling traits mediated the size– and environment–demography relationships. We found leaves were larger for taller seedlings; leaf economics traits were more conservative in taller seedlings and under high-light and low-elevation conditions. Structural equation modelling showed that a higher survival probability for taller seedlings was indirectly driven by their larger leaf area. Although taller seedlings had lower growth rates, larger and more resource-conservative leaves could promote the growth of these tall seedlings. Environmental variables did not influence seedling survival and growth directly but did influence growth indirectly by mediating trait variation. Finally, species-specific variation in traits along with size and environments was associated with the species-specific variation in seedling survival and growth. Our study suggests that not only plant ontogeny- and environment-related ecological processes, but functional traits are also important intermediary agents underlying plant size– and environment–demography relationships.

Coordination of leaf hydraulic and economic traits in Cinnamomum camphora under impervious pavement

BackgroundPaved urban environments can pose great threats to the physiological functioning and ecological services of street trees. In this context, assessment of leaf phenotypic plasticity is crucial for understanding the ecological strategy of tree species under impervious pavements.ResultsIn this study, we measured a set of leaf economic traits, hydraulic traits of Cinnamomum camphora, and surrounding environmental factors in a street site (the soil was covered by the impervious pavement) and a park site (the soil was covered by grass) in Hefei, eastern China. Compared with the park site, trees in the street site had higher stomatal length (SL), leaf thickness (LT), maximum photochemical quantum yield of photosystem II (Y(II)), and lower stomatal density (SD), specific leaf area (SLA), the leaf water potential at 50% loss of hydraulic conductance (P50), and leaf turgor loss point (TLP). Redundancy analysis showed that air relative humidity and volumetric soil water content caused these traits to be altered.ConclusionsOur results showed that C. camphora adapted to the street pavement environment through the coordination of leaf economic and leaf hydraulic traits, and adopted the slow investment return type in the leaf economic spectrum and high drought resistance to meet its actual physiological needs. This finding provides a new perspective for understanding the physiological strategies of street trees to adapt to urban pavement environments.

Leaf Economic and Hydraulic Traits Signal Disparate Climate Adaptation Patterns in Two Co-Occurring Woodland Eucalypts.

With climate change impacting trees worldwide, enhancing adaptation capacity has become an important goal of provenance translocation strategies for forestry, ecological renovation, and biodiversity conservation. Given that not every species can be studied in detail, it is important to understand the extent to which climate adaptation patterns can be generalised across species, in terms of the selective agents and traits involved. We here compare patterns of genetic-based population (co)variation in leaf economic and hydraulic traits, climate–trait associations, and genomic differentiation of two widespread tree species (Eucalyptus pauciflora and E. ovata). We studied 2-year-old trees growing in a common-garden trial established with progeny from populations of both species, pair-sampled from 22 localities across their overlapping native distribution in Tasmania, Australia. Despite originating from the same climatic gradients, the species differed in their levels of population variance and trait covariance, patterns of population variation within each species were uncorrelated, and the species had different climate–trait associations. Further, the pattern of genomic differentiation among populations was uncorrelated between species, and population differentiation in leaf traits was mostly uncorrelated with genomic differentiation. We discuss hypotheses to explain this decoupling of patterns and propose that the choice of seed provenances for climate-based plantings needs to account for multiple dimensions of climate change unless species-specific information is available.

Leaf spectroscopy reveals divergent inter- and intra-species foliar trait covariation and trait-environment relationships across NEON domains.

Concurrent measurement of multiple foliar traits to assess the full range of trade-offs among and within taxa and across broad environmental gradients is limited. Leaf spectroscopy can quantify a wide range of foliar functional traits, enabling assessment of interrelationships among traits and with the environment. We analyzed leaf trait measurements from 32 sites along the wide eco-climatic gradient encompassed by the US National Ecological Observatory Network (NEON). We explored the relationships among 14 foliar traits of 1103 individuals across and within species, and with environmental factors. Across all species pooled, the relationships between leaf economic traits (leaf mass per area, nitrogen) and traits indicative of defense and stress tolerance (phenolics, nonstructural carbohydrates) were weak, but became strong within certain species. Elevation, mean annual temperature and precipitation weakly predicted trait variation across species, although some traits exhibited species-specific significant relationships with environmental factors. Foliar functional traits vary idiosyncratically and species express diverse combinations of leaf traits to achieve fitness. Leaf spectroscopy offers an effective approach to quantify intra-species trait variation and covariation, and potentially could be used to improve the characterization of vegetation in Earth system models.

Geomorphological processes shape plant community traits in the Arctic

AbstractAimGeomorphological processes profoundly affect plant establishment and distributions, but their influence on functional traits is insufficiently understood. Here, we unveil trait–geomorphology relationships in Arctic plant communities.LocationHigh‐Arctic Svalbard, low‐Arctic Greenland and sub‐Arctic Fennoscandia.Time period2011–2018.Major taxa studiedVascular plants.MethodsWe collected field‐quantified data on vegetation, geomorphological processes, microclimate and soil properties from 5,280 plots and 200 species across the three Arctic regions. We combined these data with database trait records to relate local plant community trait composition to dominant geomorphological processes of the Arctic, namely cryoturbation, deflation, fluvial processes and solifluction. We investigated the relationship between plant functional traits and geomorphological processes using hierarchical generalized additive modelling.ResultsOur results demonstrate that community‐level traits are related to geomorphological processes, with cryoturbation most strongly influencing both structural and leaf economic traits. These results were consistent across regions, suggesting a coherent biome‐level trait response to geomorphological processes.Main conclusionsThe results indicate that geomorphological processes shape plant community traits in the Arctic. We provide empirical evidence for the existence of generalizable relationships between plant functional traits and geomorphological processes. The results indicate that the relationships are consistent across these three distinct tundra regions and that geomorphological processes should be considered in future investigations of functional traits.

Regional and local determinants of drought resilience in tropical forests.

The increase in severity of droughts associated with greater mortality and reduced vegetation growth is one of the main threats to tropical forests. Drought resilience of tropical forests is affected by multiple biotic and abiotic factors varying at different scales. Identifying those factors can help understanding the resilience to ongoing and future climate change. Altitude leads to high climate variation and to different forest formations, principally moist or dry tropical forests with contrasted vegetation structure. Each tropical forest can show distinct responses to droughts. Locally, topography is also a key factor controlling biotic and abiotic factors related to drought resilience in each forest type. Here, we show that topography has key roles controlling biotic and abiotic factors in each forest type. The most important abiotic factors are soil nutrients, water availability, and microclimate. The most important biotic factors are leaf economic and hydraulic plant traits, and vegetation structure. Both dry tropical forests and ridges (steeper and drier habitats) are more sensitive to droughts than moist tropical forest and valleys (flatter and wetter habitats). The higher mortality in ridges suggests that conservative traits are not sufficient to protect plants from drought in drier steeper habitats. Our synthesis highlights that altitude and topography gradients are essential to understand mechanisms of tropical forest's resilience to future drought events. We described important factors related to drought resilience, however, many important knowledge gaps remain. Filling those gaps will help improve future practices and studies about mitigation capacity, conservation, and restoration of tropical ecosystems.

Intraspecific variation in plant economic traits predicts trembling aspen resistance to a generalist insect herbivore.

Patterns of trait expression within some plant species have recently been shown to align with the leaf economics spectrum paradigm. Resistance to herbivores is also expected to covary with leaf economics traits. We selected 36 mature Populus tremuloides genotypes in a common garden to assess whether aspen leaf economics patterns follow those observed among species globally. We also evaluated leaf economics strategies in the context of insect resistance by conducting bioassays to determine the effects of plant traits on preference and performance of Lymantria dispar. We found that: (1) intraspecific trait patterns of P. tremuloides parallel those exhibited by the interspecific leaf economics spectrum, (2) herbivores preferred leaves from genotypes with resource-acquisitive strategies, and (3) herbivores also performed best on genotypes with resource-acquisitive strategies. We conclude that a leaf economics spectrum that incorporates defense traits is a useful tool for explaining intraspecific patterns of variation in plant strategies, including resistance to herbivores.

Leading trait dimensions in flood-tolerant plants.

Background and AimsWhile trait-based approaches have provided critical insights into general plant functioning, we lack a comprehensive quantitative view on plant strategies in flooded conditions. Plants adapted to flooded conditions have specific traits (e.g. root porosity, low root/shoot ratio and shoot elongation) to cope with the environmental stressors including anoxic sediments, and the subsequent presence of phytotoxic compounds. In flooded habitats, plants also respond to potential nutrient and light limitations, e.g. through the expression of leaf economics traits and size-related traits, respectively. However, we do not know whether and how these trait dimensions are connected.MethodsBased on a trait dataset compiled on 131 plant species from 141 studies in flooded habitats, we quantitatively analysed how flooding-induced traits are positioned in relation to the other two dominant trait dimensions: leaf economics traits and size-related traits. We evaluated how these key trait components are expressed along wetness gradients, across habitat types and among plant life forms.Key ResultsWe found that flooding-induced traits constitute a trait dimension independent from leaf economics traits and size-related traits, indicating that there is no generic trade-off associated with flooding adaptations. Moreover, individual flooding-induced traits themselves are to a large extent decoupled from each other. These results suggest that adaptation to stressful environments, such as flooding, can be stressor specific without generic adverse effects on plant functioning (e.g. causing trade-offs on leaf economics traits).ConclusionsThe trait expression across multiple dimensions promotes plant adaptations and coexistence across multifaceted flooded environments. The decoupled trait dimensions, as related to different environmental drivers, also explain why ecosystem functioning (including, for example, methane emissions) are species and habitat specific. Thus, our results provide a backbone for applying trait-based approaches in wetland ecology by considering flooding-induced traits as an independent trait dimension.

Differential Investment Strategies in Leaf Economic Traits Across Climate Regions Worldwide.

The leaf economics spectrum (LES) is the leading theory of plant ecological strategies based on functional traits, which explains the trade-off between dry matter investment in leaf structure and the potential rate of resource return, revealing general patterns of leaf economic traits investment for different plant growth types, functional types, or biomes. Prior work has revealed the moderating role of different environmental factors on the LES, but whether the leaf trait bivariate relationships are shifted across climate regions or across continental scales requires further verification. Here we use the Köppen–Geiger climate classification, a very widely used and robust criterion, as a basis for classifying climate regions to explore climatic differences in leaf trait relationships. We compiled five leaf economic traits from a global dataset, including leaf dry matter content (LDMC), specific leaf area (SLA), photosynthesis per unit of leaf dry mass (Amass), leaf nitrogen concentration (Nmass), and leaf phosphorus concentration (Pmass). Moreover, we primarily used the standardized major axis (SMA) analysis to establish leaf trait bivariate relationships and to explore differences in trait relationships across climate regions as well as intercontinental differences within the same climate type. Leaf trait relationships were significantly correlated across almost all subgroups (P < 0.001). However, there was no common slope among different climate zones or climate types and the slopes of the groups fluctuated sharply up and down from the global estimates. The range of variation in the SMA slope of each leaf relationship was as follows: LDMC–SLA relationships (from −0.84 to −0.41); Amass–SLA relationships (from 0.83 to 1.97); Amass–Nmass relationships (from 1.33 to 2.25); Nmass–Pmass relationships (from 0.57 to 1.02). In addition, there was significant slope heterogeneity among continents within the Steppe climate (BS) or the Temperate humid climate (Cf). The shifts of leaf trait relationships in different climate regions provide evidence for environmentally driven differential plant investment in leaf economic traits. Understanding these differences helps to better calibrate various plant-climate models and reminds us that smaller-scale studies may need to be carefully compared with global studies.

The carbon economics of vegetative phase change.

Across plant species and biomes, a conserved set of leaf traits govern the economic strategy used to assimilate and invest carbon. As plants age, they face new challenges that may require shifts in this leaf economic strategy. In this study, we investigate the role of the developmental transition, vegetative phase change (VPC), in altering carbon economics as plants age. We used overexpression of microRNA 156 (miR156), the master regulator of VPC, to modulate the timing of VPC in Populus tremula x alba, Arabidopsis thaliana and Zea mays to understand the impact of this transition on leaf economic traits, including construction cost, payback time and return on investment. Here, we find that VPC causes a shift from a low-cost, quick return juvenile strategy to a high-cost, high-return adult strategy. The juvenile strategy is advantageous in light-limited conditions, whereas the adult strategy provides greater returns in high light. The transition between these strategies is correlated with the developmental decline in the level of miR156, suggesting that is regulated by the miR156/SPL pathway. Our results provide an ecophysiological explanation for the existence of juvenile and adult leaf types and suggest that natural selection for these alternative economic strategies could be an important factor in plant evolution.

Variation in carbon isotope composition of plants across an aridity gradient on the Loess Plateau, China

Carbon isotope composition (indicated by leaf δ13C) reflects plants' strategies to balance carbon acquisition and water loss, which is directly linked to water use efficiency. At a large scale, leaf δ13C has been demonstrated to be closely related to climate and plant functional types; however, at a regional scale, its variation across an aridity gradient and species categories and its covariation with traits in leaf economic spectrum (LES) traits are still unclear. Here, a multivariate statistical analysis was carried out with 271 observations of leaf δ13C from 22 sampling sites on the Loess Plateau. Our results showed that (1) mean leaf δ13C did not differ significantly among life forms in C3 plants, with the maximum mean values occurring in geophytes (−26.31‰) and the minimum values occurring in lianas (−28.29‰); (2) the leaf δ13C responses of different life forms, families and species categories to climates were consistent for C3 plants, namely, they presented similar response rates to changes along the aridity gradient (represented by the moisture index); (3) climate, soil, species category, and leaf economic spectrum traits jointly explained 78.4% of the variation in leaf δ13C for C3 plants. Species category was the largest determinant of leaf δ13C variations for both C3 and C4 plants. Revealing the variation in leaf δ13C of the Loess Plateau plants not only helps us to understand plant adaptation strategies under arid conditions but also provides scientific support for ecological management in vegetation restoration regions.

Did selection for seed traits across the Cretaceous/Paleogene boundary sort plants based on ploidy?

Paleobotanists debate whether the Cretaceous/Paleogene boundary (KPB) event was selective. As the hypothesis that the KPB event selected for plants with fast-return leaf economic traits (e.g. deciduousness) has lost empirical support in recent investigations, researchers have turned to alternative hypotheses to explain an abrupt decline in primary productivity across the KPB. Two contemporary hypotheses designed to explain selectivity among plants across the KPB are that (1) polyploids exhibited greater survivorship than their diploid progenitors or counterparts (i.e. the KPB-whole genome duplication or WGD hypothesis) and that (2) plants with desiccation-tolerant (DT), i.e. orthodox, seeds exhibited greater survivorship than plants with desiccationsensitive (DS), also known as recalcitrant, seeds. Late embryogenesis abundant (LEA) protein gene families are perceived to confer DT and seed longevity among vascular plants. Non-parametric Wilcoxon signed-rank test for matched pairs and a Mann-Whitney U test reveal that plant lineages perceived to have undergone WGD across the KPB exhibit significantly greater numbers of LEA genes than those that did not. On the basis of these data, this investigation elicits a merger between the KPB-WGD and KPB-seed traits concepts. However, emphasis is shifted from the concept of WGD as an immediate adaptation to climatic stress at the KPB (the KPB-WGD hypothesis) to the concept that WGD was an exaptation, which, by definition, fortuitously enhanced the survival of vascular plants across the KPB but that probably evolved initially in other climatic contexts.

Leaf Trait Networks Based on Global Data: Representing Variation and Adaptation in Plants.

The interdependence of multiple traits allows plants to perform multiple functions. Acquiring an accurate representation of the interdependence of plant traits could advance our understanding of the adaptative strategies of plants. However, few studies focus on complex relationships among multiple traits. Here, we proposed use of leaf trait networks (LTNs) to capture the complex relationships among traits, allowing us to visualize all relationships and quantify how they differ through network parameters. We established LTNs using six leaf economic traits. It showed that significant differences in LTNs of different life forms and growth forms. The trait relationships of broad-leaved trees were tighter than conifers; thus, broad-leaved trees could be more efficient than conifers. The trait relationships of shrubs were tighter than trees because shrubs require multiple traits to co-operate efficiently to perform multiple functions for thriving in limited resources. Furthermore, leaf nitrogen concentration and life span had the highest centrality in LTNs; consequently, the environmental selection of these two traits might impact the whole phenotype. In conclusion, LTNs are useful tools for identifying key traits and quantifying the interdependence of multiple traits.

Coupling Relationship of Leaf Economic and Hydraulic Traits of Alhagisparsifolia Shap. in a Hyper-Arid Desert Ecosystem.

In this study, Alhagi sparsifolia Shap. was used to test the hypothesis that leaf economic and hydraulic traits are coupled in plants in a hyper-arid region. Five economic traits and six hydraulic traits were examined to explore the relationship. Results showed that the stomatal density (SD) on both surfaces was coupled with maximum stomatal conductance to water vapor (gwmax) and leaf tissue density (TD). SD on adaxial surface (SDaba) was significantly positively related to vein density (VD) but negatively related to leaf thickness (LT) and stomatal length on adaxial surface (SLada). Nitrogen concentration based on mass (Nmass) was significantly negatively correlated with leaf mass per area (LMA), LT, and VD, whereas nitrogen concentration based on area (Narea) was significantly positively related to LMA and TD. Mean annual precipitation (MAP) contributed the most to the changes in LT and stomatal length (SL). Soil salt contributed the most to TD, SD, and gwmax. Soli nutrients influenced the most of LMA and VD. Mean annual temperature contributed the most to Nmass and Narea. In conclusion, the economics of leaves coupled with their hydraulic traits provides an economical and efficient strategy to adapt to the harsh environment in hyper-arid regions.

Coordination of plant hydraulic and photosynthetic traits: confronting optimality theory with field measurements.

Summary Close coupling between water loss and carbon dioxide uptake requires coordination of plant hydraulics and photosynthesis. However, there is still limited information on the quantitative relationships between hydraulic and photosynthetic traits.We propose a basis for these relationships based on optimality theory, and test its predictions by analysis of measurements on 107 species from 11 sites, distributed along a nearly 3000‐m elevation gradient.Hydraulic and leaf economic traits were less plastic, and more closely associated with phylogeny, than photosynthetic traits. The two sets of traits were linked by the sapwood to leaf area ratio (Huber value, v H). The observed coordination between v H and sapwood hydraulic conductivity (K S) and photosynthetic capacity (V cmax) conformed to the proposed quantitative theory. Substantial hydraulic diversity was related to the trade‐off between K S and v H. Leaf drought tolerance (inferred from turgor loss point, –Ψtlp) increased with wood density, but the trade‐off between hydraulic efficiency (K S) and –Ψtlp was weak. Plant trait effects on v H were dominated by variation in K S, while effects of environment were dominated by variation in temperature.This research unifies hydraulics, photosynthesis and the leaf economics spectrum in a common theoretical framework, and suggests a route towards the integration of photosynthesis and hydraulics in land‐surface models.

Trait‐based responses to land use and canopy dynamics modify long‐term diversity changes in forest understories

AbstractAimLand use is the foremost cause of global biodiversity decline, but species do not respond equally to land‐use practices. Instead, it is suggested that responses vary with species traits, but long‐term data on the trait‐mediated effects of land use on communities are scarce. Here we study how forest understorey communities have been affected by two land‐use practices during 4–5 decades, and whether changes in plant diversity are related to changes in functional composition.LocationFinland.Time period1968–2019.Major taxa studiedVascular plants.MethodsWe resurveyed 245 vegetation plots in boreal herb‐rich forest understories, and used hierarchical Bayesian linear models to relate changes in diversity, species composition, average plant size, and leaf economic traits to reindeer abundance, forest management intensity, and changes in climate, canopy cover and composition. We also studied the relationship between species evenness and plant size across both space and time.ResultsIntensively managed forests decreased in species richness and had increased turnover, but management did not affect functional composition. Increased reindeer densities corresponded with increased leaf dry matter content, evenness and diversity, and decreased height and specific leaf area. Successional development in the canopy was associated with increased specific leaf area and decreased leaf dry matter content and height in the understorey over the study period. Effects of reindeer abundance and canopy density on diversity were partially mediated by vegetation height, which had a negative relationship with evenness across both space and time. Observed changes in climate had no discernible effect on any variable.Main conclusionsFunctional traits are useful in connecting vegetation changes to the mechanisms that drive them, and provide unique information compared to turnover and diversity metrics. These trait‐dependent selection effects could inform which species benefit and which suffer from land‐use changes and explain observed biodiversity changes under global change.

Coordination of leaf economics traits within the family of the world's fastest growing plants (Lemnaceae)

Abstract The duckweed family (Lemnaceae) is a group of free‐floating aquatic plants with bodies consisting of single floating fronds that multiply clonally. Although they are known to have the fastest relative growth rate (RGR) among higher plants, their functional trait coordination in relation to within‐family variation of RGR is poorly understood. We tested how duckweed species fit within the trait covariation patterns known as the world‐wide leaf economics spectrum (LES). To this end, several functional traits were evaluated for 15 duckweed species, and their covariation patterns were compared with those in the global database of plant functional traits. As a group, duckweeds exhibited the most acquisitive suite of traits, with extremely small leaf mass per area (LMA), short life span and high mass‐based photosynthetic rate (Amass). These LES traits showed a tight correlation with RGR, corroborating our hypothesis that acquisitive leaf resource economics underpins their extremely high RGR. However, unlike other higher plants, LMA showed weak association with leaf life span and Amass within duckweed family. We also found a unique positive correlation between duckweed LMA and area‐based photosynthetic rates, an indication that their LMA represents different functional significance compared to typical higher plants. Synthesis. Duckweeds, the world's fastest growing plants, mostly follow the world‐wide LES and locate at its extreme end. The slight deviation from the LES highlights that duckweeds experience some physical and chemical constraints not faced by other higher plants.

Leaf vein density enhances vascular redundancy instead of carbon uptake at the expense of increasing water leaks in oaks

Predicting plant growth from functional traits has been a long-term goal of experimental botany. Early studies considered that resource traits align across a single axis, from high to low growth rates. The drivers of nocturnal and cuticular leaf conductances have received much recent attention, but how they align with other functional traits along axes of resource use remains to be investigated. Here we examined correlated evolution of secondary growth, leaf economic, stomatal, venation and gas exchange traits across 12 Quercus species growing in a common garden. Variation in growth correlated with variation in assimilation and nocturnal conductance (gn). Our observations are consistent with the hypothesis of a negative relationship between SLA and leaf vein density (VLAall) within oaks, indicating that increased VLAall is a strategy to enhance leaf vascular redundancy against stress or perturbation as the degree of sclerophylly increases. gn was negatively correlated with growth and decoupled from daytime conductance and photosynthesis. gn seemed to be a passive process in this genus, apparently driven by enhanced water supply that results from increased VLAall. We also observed a positive relationship between leaf vein density and cuticular conductance, indicating that increasing VLAall may incur significant water costs under strong drought.

Consistent trait-environment relationships within and across tundra plant communities.

A fundamental assumption in trait-based ecology is that relationships between traits and environmental conditions are globally consistent. We use field-quantified microclimate and soil data to explore if trait-environment relationships are generalizable across plant communities and spatial scales. We collected data from 6,720 plots and 217 species across four distinct tundra regions from both hemispheres. We combined these data with over 76,000 database trait records to relate local plant community trait composition to broad gradients of key environmental drivers: soil moisture, soil temperature, soil pH and potential solar radiation. Results revealed strong, consistent trait-environment relationships across Arctic and Antarctic regions. This indicates that the detected relationships are transferable between tundra plant communities also when fine-scale environmental heterogeneity is accounted for, and that variation in local conditions heavily influences both structural and leaf economic traits. Our results strengthen the biological and mechanistic basis for climate change impact predictions of vulnerable high-latitude ecosystems.