Variation In Leaf Traits Research Articles

Intraspecific variation in leaf traits facilitates the occurrence of trees at the Amazonia–Cerrado transition

The ability of plant species to adjust key functional traits through intraspecific variation may determine their success in persisting on our planet in the future, especially in unstable habitats, such as the Amazonia–Cerrado transition zone. We assessed intraspecific variation in 12 leaf morphological and anatomical traits for four tree species along a savanna–forest gradient, including rocky cerrado, typical cerrado and woodland savanna. Generally, all evaluated species showed great intraspecific variation. Our findings demonstrate that trees occurring in the woodland savanna are potentially more vulnerable to climate change, while in the cerrado the individuals presented higher tolerance to water deficit and high temperatures. Trees occurring in open-canopy habitats showed smaller stomata, higher stomata and trichome densities, compared to the same species growing in the woodland savanna. In contrast, the individuals in the woodland savanna shift leaf traits to increase resource acquisition (e.g. light), showing higher specific leaf area and larger stomata, compared to cerrado individuals. We have shown that vegetation-induced shifts in leaf morphological and anatomical traits are a major effect in within-species variability, with consequences for persistence and tolerance of species under future climatic conditions.

Leaf trait variability explains how plant community composition changes under the intense pressure of deer herbivory

AbstractThere is growing evidence indicating that intraspecific trait variation (ITV) plays a prominent role in determining plant community composition. In this study, we investigated the significance of ITV in identifying the processes that shape the development of forest understory plant communities in an area in which excessive herbivory by overabundant deer populations has been an issue. We measured functional traits (height, leaf area, leaf mass per area, leaf dry matter content, and leaf toughness) of 13 forest floor plant species growing in two contrasting sites in which deer were overabundant or had been completely excluded, respectively, and examined the relationships between species dominance and interspecific trait variation and ITV. We detected variations in the trait plasticity of size and morphological features among species, reflecting species‐specific strategies in response to herbivory and consequently observed marked differences in species composition and diversity at the two sites. Notably, small stature and less costly leaves were identified as important traits that enable plants to persist under conditions of intense deer herbivory probably because such plants are less exposed to herbivory and simultaneously optimize carbon assimilation. In contrast, large‐sized plants with costly leaves tended to dominate the plant community in the absence of deer herbivory, as these plants would tend to gain a competitive advantage with respect to the acquisition of space and light. The findings of this study indicate that a focus on ITV represents a promising approach for determining the general ecological patterns of plant communities responding to environmental disturbance.

Functional leaf traits indicate phylogenetic signals in forests across an elevational gradient in the central Himalaya.

Traits are the primary attributes that distinguish a species niche. Species and higher taxa are part of a structured phylogeny, and variation in plant traits depends on lineage as well as on environmental conditions. Therefore, it is crucial to investigate linkages between taxonomic identity, shared ancestry, and environment for understanding the variation in leaf traits. We investigated the evolutionary relationships, based on multiple gene sequences among 26 plant species sampled along an elevational gradient from 650 to 3600m a.s.l. in the central Himalaya. We tested for the phylogenetic signal based on three different measures in 10 leaf traits having a significant association with the resource acquisition-conservation trade-offs axis and influencing plant growth, development, and ecological performance. We further assessed the role of elevation and growth forms as the potential drivers of leaf traits variation while controlling for phylogeny. 5 out of 10 leaf traits showed significant phylogenetic signal. Plant species clustered more often by growth forms at the tips of the phylogeny indicating multiple instances of independent evolution. Evergreen taxa showed niche separation with deciduous and incorporated larger trait variation. Trait variations were guided by both growth forms and elevation when accounted for phylogeny. Growth form has a higher contribution to trait variation compared to elevation. Trade-offs were detected between resource conservation and resource acquisition machinery traits (that would maximise carbon gain), differing between growth forms and along elevation.

Prediction of leaf traits of lianas and trees via the integration of wavelet spectra in the visible-near infrared and thermal infrared domains

Predicting leaf traits using models based on spectroscopic data can provide essential information to advance ecological research and future Earth system models. Most current models are based on Partial Least Squares Regression (PLSR) algorithms that attempt to predict a set of leaf traits of several plant groups using leaf spectra. However, PLSR models tend to be inconsistent in describing the importance of absorption features when used to predict leaf traits. Likewise, the effect of contrasting absorption features of different plant groups on the prediction and evaluation of PLSR models is not well understood. Hence, this study focuses on using wavelet spectra to overcome current PLSR's limitation and improve leaf trait predictions. Specifically, we explored the use of visible–near-infrared (0.45–1.0 μm) and mid- long-wave infrared spectra (2.55–11 μm) to predict three-leaf traits of lianas and trees: Leaf Mass Area (LMA), Water Content (WC), and Equivalent Water Thickness (EWT). We also compare the effect of life forms on the prediction of traits by using sun leaves collected from 14 liana species and 21 tree species (n = 700) from a Neotropical Dry Forest. On each leaf, reflectance measurements were performed for both selected spectral regions; then, leaf traits were estimated from a leaf segment. Leaf reflectance was first resampled and then processed using continuous wavelet transformation (CWT) to derive the wavelet spectra. PLSR models linking the leaf traits and the reflectance or wavelet spectra were compared. Our results reveal that PLSR models based on wavelet spectra require fewer components to predict traits (13–16) than those based on reflectance (25–29). In addition, PLSR models' performance (e.g., R2) of testing datasets tend to be higher for models based on wavelet spectra (LMA = 0.83; WC = 0.77; EWT = 0.68) than reflectance (LMA = 0.78; WC = 0.76; EWT = 0.49). Wavelet spectra models also seem to better characterize absorption features that drive the variability of leaf traits than models based on reflectance. However, life forms play an essential role in model performance, where the prediction of lianas' traits presenting lower R2 (R2 = 0.61 ± 0.25) than trees' traits (R2 = 0.69 ± 0.15) regardless of the type of spectra or leaf trait. Our findings highlight the use of wavelet spectra to overcome limitations of the PLSR models for predicting leaf traits and the need to explore potential bias associated with plant groups on the model evaluations.

Effects of ontogenetic stage and leaf age on leaf functional traits and the relationships between traits in Pinus koraiensis

Investigating the effects of ontogenetic stage and leaf age on leaf traits is important for understanding the utilization and distribution of resources in the process of plant growth. However, few studies have been conducted to show how traits and trait-trait relationships change across a range of ontogenetic stage and leaf age for evergreen coniferous species. We divided 67 Pinus koraiensis Sieb. et Zucc. of various sizes (0.3–100 cm diameter at breast height, DBH) into four ontogenetic stages, i.e., young trees, middle-aged trees, mature trees and over-mature trees, and measured the leaf mass per area (LMA), leaf dry matter content (LDMC), and mass-based leaf nitrogen content (N) and phosphorus content (P) of each leaf age group for each sampled tree. One-way analysis of variance (ANOVA) was used to describe the variation in leaf traits by ontogenetic stage and leaf age. The standardized major axis method was used to explore the effects of ontogenetic stage and leaf age on trait-trait relationships. We found that LMA and LDMC increased significantly and N and P decreased significantly with increases in the ontogenetic stage and leaf age. Most trait-trait relationships were consistent with the leaf economic spectrum (LES) at a global scale. Among them, leaf N content and LDMC showed a significant negative correlation, leaf N and P contents showed a significant positive correlation, and the absolute value of the slopes of the trait-trait relationships showed a gradually increasing trend with an increasing ontogenetic stage. LMA and LDMC showed a significant positive correlation, and the slopes of the trait-trait relationships showed a gradually decreasing trend with leaf age. Additionally, there were no significant relationships between leaf N content and LMA in most groups, which is contrary to the expectation of the LES. Overall, in the early ontogenetic stages and leaf ages, the leaf traits tend to be related to a "low investment-quick returns" resource strategy. In contrast, in the late ontogenetic stages and leaf ages, they tend to be related to a "high investment-slow returns" resource strategy. Our results reflect the optimal allocation of resources in Pinus koraiensis according to its functional needs during tree and leaf ontogeny.

Individual-level leaf trait variation and correlation across biological and spatial scales.

Even with increasing interest in the ecological importance of intraspecific trait variation (ITV) for better understanding ecological processes, few studies have quantified ITV in seedlings and assessed constraints imposed by trade‐offs and correlations among individual‐level leaf traits. Estimating the amount and role of ITV in seedlings is important to understand tree recruitment and long‐term forest dynamics. We measured ten different size, economics, and whole leaf traits (lamina and petiole) for more than 2,800 seedlings (height ≥ 10 cm and diameter at breast height < 1 cm) in 283 seedling plots and then quantified the amount of ITV and trait correlations across two biological (intraspecific and interspecific) and spatial (within and among plots) scales. Finally, we explored the effects of trait variance and sample size on the strength of trait correlations. We found about 40% (6%–63%) variation in leaf‐level traits was explained by ITV across all traits. Lamina and petiole traits were correlated across biological and spatial scales, whereas leaf size traits (e.g., lamina area) were weakly correlated with economics traits (e.g., specific lamina area); lamina mass ratio was strongly related to the petiole length. Trait correlations varied among species, plots, and different scales but there was no evidence that the strength of trait relationships was stronger at broader than finer biological and spatial scales. While larger trait variance increased the strength of correlations, the sample size was the most important factor that was negatively related to the strength of trait correlations. Our results showed that a large amount of trait variation was explained by ITV, which highlighted the importance of considering ITV when using trait‐based approaches in seedling ecology. In addition, sample size was an important factor that influenced the strength of trait correlations, which suggests that comparing trait correlations across studies should consider the differences in sample size.

Reprint of: Drivers of within-tree leaf trait variation in a tropical planted forest varying in tree species richness

In plant ecology, community-weighted trait means are often used as predictors for ecosystem functions. More recently, also within-species trait variation has been confirmed to contribute to ecosystem functioning. We here go even further and assess within-individual trait variation, assuming that every leaf in a plant individually adjusts to its micro-environment. Using forest plots varying in tree species richness (Sardinilla experiment, Panama), we analysed how leaf traits within individual trees vary along the vertical crown gradient. Furthermore, we tested whether niche partitioning in mixed stands results in a decrease of within-species leaf trait variation and whether niche partitioning can be also observed at the level of individual trees. We focused on leaf traits that describe the growth strategy along the conservative-acquisitive spectrum of growth. We found a decrease in within-species variation of specific leaf area (SLA) with increasing neighbourhood species richness. Both sampling height and local neighbourhood richness contributed to explaining within-species leaf trait variation, which however, varied in importance among different species and traits. With increasing sampling height, leaf dry matter content (LDMC), carbon to nitrogen ratio and lignin content increased, while leaf nitrogen concentration (leaf N), SLA, cellulose and hemicellulose decreased. Variation in leaf N decreased with increasing neighbourhood species richness, while the magnitude of within-individual variation of most traits was unaffected by neighbourhood species richness. Our results suggest an increased niche partitioning with increasing species richness both in a plant community and at the level of individual plants. Our findings highlight the importance of including within-individual trait variation to understand biodiversity-ecosystem functioning relationships.

Minimum temperature drives community leaf trait variation in secondary montane forests along a 3000-m elevation gradient in the tropical Andes

ABSTRACT Background: Leaf functional traits (LFT) influence resource acquisition and are important for understanding ecosystem processes. Climate and land use are key filters of community composition and LFT, however, how the relative importance of these filter changes with elevation has been little studied in the Andes. Aims: To gain insight into the functional response of Andean forests to climate and disturbance in naturally regenerated forest stands. Methods: We measured leaf blade thickness (LBT), leaf area (LA), specific leaf area (SLA), and leaf dry matter content (LDMC) from 13 secondary forest communities, along a 3000-m elevation transect. We derived basal area-weighted mean community (CWM) trait values to assess the effect of climate and disturbance on the functional structure of regenerating tree communities. Results: Community LFT progressively shifted along the elevation gradient driven by changes in temperature and successional stages towards communities with thicker leaves with low SLA. Reduction in LDMC with elevation suggested that both succulence and sclerophylly were important strategies in these forests. Conclusions: Our findings reinforce the validity of LFT as a powerful predictor to explore the ecological strategies of tree species in climate scenarios. Warmer conditions could result in a shift from slower to faster resource acquisition strategies at higher elevations.

Eucalyptusspp. leaf traits determine litter processing by fungi and invertebrates

AbstractEucalyptusis one of the most cultivated genera globally. Conversion of native forests intoEucalyptusspp. monocultures leads to species‐specific changes in the quality of the litter that contributes to the structure and function of allochthonous‐based aquatic systems.We used a microcosm approach to compare the relative importance of structural and chemical leaf trait variability among congeneric exoticEucalyptusspecies (E. camaldulensis,E. globulus,E. grandis, andE. nitens) and two Portuguese native species—alder (Alnus glutinosa) and oak (Quercus robur)—on microbial‐mediated decomposition and invertebrate shredder (Trichoptera:Sericostoma vittatum) consumption.Structural leaf traits, rather than chemical characteristics, appeared to be the main determinants of leaf‐processing dynamics. Differences between the exotic species were mainly determined by the persistence (E. globulus,E. grandis, andE. nitens) or detachment (E. camaldulensis) of the cuticular barrier soon after immersion. Detachment favoured an earlier and higher level of fungal colonisation, as well as a higher mass loss.Sericostoma vittatumexhibited higher consumption rates when fed by the nitrogen‐rich and softer alder leaves,E. camaldulensis, and oak. Consistently lower consumption rates were observed in the other threeEucalyptusspecies (64–77% lower thanE. camaldulensis). Leaf litter from these species was colonised by a lower number of fungal species and was dominated byFlagellospora curta.Results suggest that streams adjacent toE. camaldulensismonocultures receive a continuous supply of easily degradable organic matter throughout the year. The potential effect of subsidies from this species in alleviating the general negative impacts ofEucalyptusplantations on native bordered aquatic systems remains to be evaluated.

Centre-periphery approaches based on geography, ecology and historical climate stability: what explains the variation in morphological traits of Bulnesia sarmientoi?

The centre-periphery hypothesis posits that higher species performance is expected in geographic and ecological centres rather than in peripheral populations. However, this is not the commonly found pattern; therefore, alternative approaches, including the historical dimension of species geographical ranges, should be explored. Morphological functional traits are fundamental determinants of species performance, commonly related to environmental stability and productivity. We tested whether or not historical processes may have shaped variations in tree and leaf traits of the Chaco tree Bulnesia sarmientoi. Morphological variation patterns were analysed from three centre-periphery approaches: geographical, ecological and historical. Tree (stem and canopy) and leaf (leaf size and specific leaf area) traits were measured in 24 populations across the species range. A principal component analysis was performed on morphological traits to obtain synthetic variables. Linear mixed-effects models were used to test which of the implemented centre-periphery approaches significantly explained trait spatial patterns. The patterns retrieved from the three centre-periphery approaches were not concordant. The historical approach revealed that trees were shorter in centre populations than in the periphery. Significant differences in leaf traits were observed between the geographical centre and the periphery, mainly due to low specific leaf area values towards the geographical centre. We did not find any pattern associated with the ecological centre-periphery approach. The decoupled response between leaf and tree traits suggests that these sets of traits respond differently to processes occurring at different times. The geographical and historical approaches showed centres with extreme environments in relation to their respective peripheries, but the historical centre has also been a climatically stable area since the Last Glacial Maximum. The historical approach allowed for the recovery of historical processes underlying variation in tree traits, highlighting that centre-periphery delimitations should be based on a multi-approach framework.

Mistletoes and their eucalypt hosts differ in the response of leaf functional traits to climatic moisture supply.

Trade-offs between photosynthesis and the costs of resource capture inform economic strategies of plants across environmental gradients and result in predictable variation in leaf traits. However, understudied functional groups like hemiparasites that involve dramatically different strategies for resource capture may have traits that deviate from expectations. We measured leaf traits related to gas exchange in mistletoes and their eucalypt hosts along a climatic gradient in relative moisture supply, measured as the ratio of precipitation to pan evaporation (P/Ep), in Victoria, Australia. We compared traits for mistletoes vs. hosts as functions of relative moisture supply and examined trait-trait correlations in both groups. Eucalypt leaf traits responded strongly to decreasing P/Ep, consistent with economic theory. Leaf area and specific leaf area (SLA) decreased along the P/Ep gradient, while C:N ratio, leaf thickness, N per area, and δ13C all increased. Mistletoes responded overall less strongly to P/Ep based on multivariate analyses; individual traits sometimes shifted in parallel with those of hosts, but SLA, leaf thickness, and N per area showed no significant change across the gradient. For mistletoes, leaf thickness was inversely related to leaf dry matter content (LDMC), with no relationship between SLA and mass-based N. In mistletoes, reduced costs of transpiration (reflecting their lack of roots) and abundant succulent leaf tissue help account for observed differences from their eucalypt hosts. Trait-based analysis of atypical functional types such as mistletoes help refine hypotheses based on plant economics and specialized adaptations to resource limitation.

Intraspecific variations in leaf traits, productivity and resource use efficiencies in the dominant species of subalpine evergreen coniferous and deciduous broad‐leaved forests along the altitudinal gradient

Abstract Many studies have reported intraspecific variations in leaf functional traits, but their contribution to plant performance and ecosystem function are poorly understood. We studied altitudinal gradients of intraspecific variations in leaf traits, productivity and resource use efficiency in the dominant species of subalpine evergreen coniferous and deciduous broad‐leaved forests in Japan. We addressed three hypotheses, which are exclusive to each other. (1) Leaf traits vary along the leaf economics spectrum (LES). Plants that grow at lower and higher altitudes have fast‐ and slow‐return strategies, respectively, which improve productivity or resource use efficiency in the respective habitat. (2) Leaf trait variations are not consistent with the LES, but they contribute to improving productivity or resource use efficiency in the respective habitat. (3) Leaf trait variations do not contribute to improving productivity or resource use efficiency at higher altitudes. On the studied mountain range, Fagus crenata, a deciduous broad‐leaved tree, and Abies mariesii, an evergreen conifer, are the dominant species at lower and higher altitudes respectively. In F. crenata, leaf mass per area (LMA) and nitrogen concentrations were higher at higher altitudes. The net assimilation rate and light use efficiency during the growing season were greater at higher altitudes, which compensated for the shorter growing season in terms of annual productivity. In A. mariesii, the LMA was lower and the leaf life span was unchanged at higher altitudes. Productivity and resource use efficiency decreased with altitude. Synthesis. We conclude that F. crenata improves its productivity and resource use efficiency at higher altitudes by altering its leaf functional traits (Hypothesis 2), whereas alterations to leaf traits in A. mariesii are not associated with any improvement at higher altitudes (Hypothesis 3), which may result from the negative impact of environmental stress. Hence, the ecological significance of altitudinal variations in leaf traits depends on species and environment.

Photosynthetic response of young oaks to biochar amendment in field conditions over 3 years

ABSTRACT Amendment by biochar made by thermal degradation of biomass is expected to enhance carbon sequestration through stimulating carbon assimilation by plants. We clarified the effect of biochar amendment on the photosynthesis of trees in forest ecosystems. Biochar was applied to young oak trees (Quercus serrata) in temperate deciduous forest at rates of 0, 5, 10 and 20 Mg ha−1 in four plots (C0, C5, C10, and C20). The variation in photosynthetic parameters (the maximum photosynthetic rate: Pmax, maximum carboxylation rate: Vcmax and the potential rate of electron transport: Jmax) and leaf traits (the stomatal conductance: gc, leaf mass per area (LMA) and leaf nutrient concentrations) were examined every month during the growing seasons for 3 years. Pmax generally increased in C5 and C10 and did not increase in C20. Similarly, Vcmax and Jmax increased in C5 and C10 and correlated significantly positively with Pmax, suggesting that biochar amendment basically increased the photosynthetic rate through improvements in physiological activities but that there was a maximum useful dosage. We also found that gc, LMA and leaf nutrient (N, Mg, and S) showed significant positive correlations with Pmax, indicating that an increase in photosynthetic rates would be supported by these leaf traits. However, stimulation of photosynthesis became smaller year by year, indicating that the effects of biochar amendment faded gradually. We concluded that biochar amendment basically improved the photosynthesis of oak trees in the forest through the change of all gc, LMA and leaf nutrient concentrations but declined yearly.

Predictability of leaf traits with climate and elevation: a case study in Gongga Mountain, China.

Leaf mass per area (Ma), nitrogen content per unit leaf area (Narea), maximum carboxylation capacity (Vcmax) and the ratio of leaf-internal to ambient CO2 partial pressure (χ) are important traits related to photosynthetic function, and they show systematic variation along climatic and elevational gradients. Separating the effects of air pressure and climate along elevational gradients is challenging due to the covariation of elevation, pressure and climate. However, recently developed models based on optimality theory offer an independent way to predict leaf traits and thus to separate the contributions of different controls. We apply optimality theory to predict variation in leaf traits across 18 sites in the Gongga Mountain region. We show that the models explain 59% of trait variability on average, without site- or region-specific calibration. Temperature, photosynthetically active radiation, vapor pressure deficit, soil moisture and growing season length are all necessary to explain the observed patterns. The direct effect of air pressure is shown to have a relatively minor impact. These findings contribute to a growing body of research indicating that leaf-level traits vary with the physical environment in predictable ways, suggesting a promising direction for the improvement of terrestrial ecosystem models.

The GenTree Leaf Collection: Inter‐ and intraspecific leaf variation in seven forest tree species in Europe

AbstractMotivationTrait variation within species can reveal plastic and/or genetic responses to environmental gradients, and may indicate where local adaptation has occurred. Here, we present a dataset of rangewide variation in leaf traits from seven of the most ecologically and economically important tree species in Europe. Sample collection and trait assessment are embedded in the GenTree project (EU‐Horizon 2020), which aims at characterizing the genetic and phenotypic variability of forest tree species to optimize the management and sustainable use of forest genetic resources. Our dataset captures substantial intra‐ and interspecific leaf phenotypic variability, and provides valuable information for studying the relationship between ecosystem functioning and trait variability of individuals, and the response and resilience of species to environmental changes.Main types of variable containedWe chose morphological and chemical characters linked to trade‐offs between acquisition and conservation of resources and water use, namely specific leaf area, leaf size, carbon and nitrogen content and their ratio, and the isotopic signature of stable isotope 13C and 15N in leaves.Spatial location and grainWe surveyed between 18 and 22 populations per species, 141 in total, across Europe.Time periodLeaf sampling took place between 2016 and 2017.Major taxa and level of measurementWe sampled at least 25 individuals in each population, 3,569 trees in total, and measured traits in 35,755 leaves from seven European tree species, i.e. the conifers Picea abies, Pinus pinaster and Pinus sylvestris, and the broadleaves Betula pendula, Fagus sylvatica, Populus nigra and Quercus petraea.Software formatThe data files are in ASCII text, tab delimited, not compressed.

Taxon-specific variability of leaf traits in three long-ranging fossil-species of the Paleogene and Neogene: Responses to climate?

Taxon-specific variability of leaf traits in three long-ranging fossil-species of the Paleogene and Neogene: Responses to climate?

Herbivory and leaf traits of two tree species from different successional stages in a tropical dry forest

ABSTARCT Leaf traits are analyzed as essential drivers for the evolutionary and ecological role of plant defense mechanisms. Plants show leaf trait variation as a response to the diverse environmental conditions, like different successional stages. Those variations can impact leaf herbivory rates and drive changes in the allocation of plant resources. In this study, we aimed at comparing the expression of leaf defenses in established plants over different successional stages in a tropical dry forest to understand how these defenses modify the plant–herbivore interactions based on herbivory rates. We analyzed physical leaf traits (specific leaf area, thickness, and density), nutrient content (N, P, and K), total phenolic compounds, and leaf herbivory, of the native tree species Aspidosperma pyrifolium and Cenostigma pyramidale, in early- and late-successional stage areas. Results showed that the plant investment in defenses varies according to the successional stage and that both species have similar defense strategies, confirming the resource availability hypothesis. Individuals from the early stage adopt a strategy to lower sclerophylly, higher nutrient content and less phenolic compounds, while the late-stage individuals showed an opposite behaviour. For both species in this study, the average percentage of leaf herbivory observed was 40% higher in the early compared to the late-stage area. Our data indicate that plant defenses are tightly coupled to sclerophylly and investments in secondary metabolites, and the environmental conditions of different successional stage drive that plasticity in such leaf traits.

Trade-off relationship between light interception and leaf water shedding at different canopy positions of 73 broad-leaved trees of Yangji Mountain in Jiangxi Province, China

<p indent=0mm>As light interception and leaf water shedding may require different leaf traits, trade-offs may exist between the leaves’ abilities in light interception and leaf water shedding. Moreover, such trade-offs may vary with the vertical canopy position as leaf traits vary with tree height. We studied the variations in leaf traits at different canopy positions to study how canopy positions would affect the trade-off between the traits related to light interception and leaf water shedding in subtropical broad-leaved trees. We used the standardized major axis regression method to analyze the relationships among leaf morphological traits (leaf thickness and leaf length/width ratio), configuration traits (leaf angle and leaf drip tip length), and physiological traits (photosynthesis-light saturation point and photosynthesis-light compensation point) between sun and shade leaves. The results are as follows: (i) There was no significant difference in the leaf thickness and leaf length/width ratio at different canopy positions (<italic>P</italic>>0.05). The leaf angle (34.92°±1.15°), light saturation point ((954.89±27.86) µmol/(m²·s)), and light compensation point ((29.45±1.02) µmol/(m²·s)) at the upper canopy were significantly higher than those at the lower canopy (leaf angle: 16.66°±0.50°, light saturation point: (520.74±15.47) µmol/(m²·s), and light compensation point: (12.54±0.38) µmol/(m²·s); <italic>P<</italic>0.05). However, the leaf drip tip length was significantly shorter at the upper canopy position ((4.26±0.15) mm) than at the lower canopy position ((7.18±0.22) mm; <italic>P</italic><0.05). (ii) There were significant correlations among leaf angle, leaf drip tip length, light saturation point, and light compensation point at different canopy positions (<italic>P</italic><0.05), but the leaf drip tip length and leaf length/width ratio were only weakly correlated at the upper canopy leaves (<italic>P</italic><0.05). (iii) Common slope (<italic>P</italic>>0.05) and isometric scaling existed among the leaf angle, light saturation point, and light compensation point at different canopy positions, but there was no common constant (<italic>P</italic><0.05). These results indicated that the canopy position does not alter the trade-off strategy between light interception and leaf water shedding. The leaf drip tip length and inclination were mainly affected by the light saturation point and light compensation point.

Patterns in intraspecific variation in root traits are species‐specific along an elevation gradient

Abstract Intraspecific trait variation is an important driver of plant performance in different environments. Although roots acquire essential resources that vary with the environment, most studies have focused on intraspecific variation in leaf traits, and research on roots is often restricted to a few species. It remains largely unclear how and to what extent root traits vary with the environment and whether general intraspecific patterns exist across species. We compared intraspecific variation in specific root length (SRL), root diameter, root tissue density (RTD) and root branching density of 11 species along a 1,000 m elevation gradient in the French Alps. We tested (a) the extent of intraspecific versus interspecific root trait variation along the gradient, (b) whether intraspecific trait patterns with elevation were consistent among species and (c) whether environmental variables better explained intraspecific variation in root traits than elevation. Specifically, we hypothesised that within a species, root trait values would adjust to enhance resource acquisition (either through an increase in SRL or root diameter, and/or in branching density) and/or conservation (increased RTD) at higher elevations. Species identity explained most of the overall variation in root traits. Elevation explained only a minor proportion of intraspecific root trait variation, which was larger within than between elevations. Also, trait relationships with elevation rarely agreed with our hypotheses, varied strongly across species and were often differently related to environmental variation. Generally, climate, soil and vegetation properties better explained intraspecific root variation than elevation, but these relationships were highly species‐dependent. Along complex environmental gradients where multiple properties simultaneously change, roots of different species vary in different ways, leading to species‐specific patterns in intraspecific root trait variation. The lack of support for our hypotheses may be caused by the multiple interactions between environmental properties, small‐scale soil heterogeneity, species phylogeny and changing plant–plant interactions. Our findings suggest that, to enhance our understanding of the effects of environmental change on plant performance, we need to better integrate the multiple dimensions of plant responses to change and measure a broader set of root traits and environmental variables. A free Plain Language Summary can be found within the Supporting Information of this article.

Drivers of within-tree leaf trait variation in a tropical planted forest varying in tree species richness

In plant ecology, community-weighted trait means are often used as predictors for ecosystem functions. More recently, also within-species trait variation has been confirmed to contribute to ecosystem functioning. We here go even further and assess within-individual trait variation, assuming that every leaf in a plant individually adjusts to its micro-environment. Using forest plots varying in tree species richness (Sardinilla experiment, Panama), we analysed how leaf traits within individual trees vary along the vertical crown gradient. Furthermore, we tested whether niche partitioning in mixed stands results in a decrease of within-species leaf trait variation and whether niche partitioning can be also observed at the level of individual trees. We focused on leaf traits that describe the growth strategy along the conservative-acquisitive spectrum of growth. We found a decrease in within-species variation of specific leaf area (SLA) with increasing neighbourhood species richness. Both sampling height and local neighbourhood richness contributed to explaining within-species leaf trait variation, which however, varied in importance among different species and traits. With increasing sampling height, leaf dry matter content (LDMC), carbon to nitrogen ratio and lignin content increased, while leaf nitrogen concentration (leaf N), SLA, cellulose and hemicellulose decreased. Variation in leaf N decreased with increasing neighbourhood species richness, while the magnitude of within-individual variation of most traits was unaffected by neighbourhood species richness. Our results suggest an increased niche partitioning with increasing species richness both in a plant community and at the level of individual plants. Our findings highlight the importance of including within-individual trait variation to understand biodiversity-ecosystem functioning relationships.