Specific Leaf Area Responses Research Articles

Idiosyncrasy and predictability in intraspecific trait–climate relationships of grasses

AbstractMany plant species can exhibit remarkable variation in leaf characteristics, depending on their abiotic and biotic environment. Environmental changes therefore have the potential to alter leaf traits, which in turn scale up to influence ecosystem processes including net primary productivity, susceptibility to fire, and palatability to herbivores. It is not well understood how consistent trait–environment relationships are among species, across sites and over time. This presents a fundamental challenge for functional ecology, because no study can measure all relevant species in all places at all times. Thus, understanding the limits of transferability is critical. We collected leaf trait measurements on 13 species of grass (family: Poaceae) across 11 sites and five years (n = 3091 individuals). Sites were arrayed along a spatial precipitation gradient in coastal northern California (annual precipitation of 590–1350 mm) with substantial interannual precipitation variability (from 60% below the 30‐year average to 100% above average). Temporal and spatial linear relationships between precipitation and specific leaf area (SLA) appear at first idiosyncratic, with each species sometimes displaying positive and sometimes negative responses. However, this variation arises from sampling different portions of an underlying hump‐shaped relationship, which was shared across most species. This hump‐shaped relationship was driven primarily by changes in leaf tissue density. These results suggest the potential for transferability among species, as well as between space and time, as long as the gradients are sufficiently long to capture the nonlinear response. Future work could explore the physiological basis of the nonlinear SLA response, including the possibility that distinct physiological mechanisms are operating at the two extremes of the gradient.

Diversity and mean specific leaf area of Mediterranean woody vegetation changes in response to summer drought across a double stress gradient: The role of phenotypic plasticity

AbstractAimMany aspects of vegetation response to increased drought remain uncertain but it is expected that phenotypic plasticity may be key to early adaptation of plants to environmental stress. In this work we observe the response of specific leaf area (SLA) of woody shrub vegetation to the summer drought typical of the Mediterranean climate. In addition, to observe the possible interaction between the impact of drought and the environmental characteristics of the ecosystems, communities from different edaphic and structural contexts distributed along the double stress gradient of the Mediterranean mountains (high temperature and low precipitation at low elevation; low temperature and high irradiation at high elevation) have been analysed.LocationCentral Mountain range of the Iberian Peninsula.MethodsAlong the entire altitudinal gradient, 33 shrub communities belonging to different habitat typologies (shrublands, rocky areas, hedgerows, understorey) were sampled before and after the passage of summer, both in 2017 and 2019. A total of 1724 individuals and 15,516 leaves were collected and measured to estimate the mean values and diversity of SLA of each community.ResultsThe community‐weighted mean and functional divergence have inverse quadratic relationships with the environmental gradient. Shrub communities at both ends of the gradient have low mean SLA values and high functional divergence of this trait. Summer drought implies a generalised decrease in the mean SLA of the communities throughout the gradient, as well as an alteration in functional richness and uniformity. However, the effect of summer drought on the plant community is mediated by the microenvironmental characteristics of its habitat.ConclusionsDrought acclimatisation of shrub communities through phenotypic plasticity leads to rapid changes in their functional leaf structure. In the long term, our results point to an increase in plant conservative strategies, reduced ecosystem productivity, slower nutrient recycling and the reduction of communities of specific habitats as drought increases.

Phenotypic plasticity and selection on leaf traits in response to snowmelt timing and summer precipitation

Vegetative traits of plants can respond directly to changes in the environment, such as those occurring under climate change. That phenotypic plasticity could be adaptive, maladaptive, or neutral. We manipulated the timing of spring snowmelt and amount of summer precipitation in factorial combination and examined responses of specific leaf area (SLA), trichome density, leaf water content (LWC), photosynthetic rate, stomatal conductance and intrinsic water-use efficiency (iWUE) in the subalpine herb Ipomopsis aggregata. The experiment was repeated in three years differing in natural timing of snowmelt. To examine natural selection, we used survival, relative growth rate, and flowering as fitness indices. A 50% reduction in summer precipitation reduced stomatal conductance and increased iWUE, and doubled precipitation increased LWC. Combining natural and experimental variation, earlier snowmelt reduced soil moisture, photosynthetic rate and stomatal conductance, and increased trichome density and iWUE. Precipitation reduction reversed the mortality selection favoring high stomatal conductance under normal and doubled precipitation, and higher LWC improved growth. Earlier snowmelt is a strong signal of climate change and can change expression of leaf morphology and gas exchange traits, just as reduced precipitation can. Stomatal conductance and SLA showed adaptive plasticity under some conditions.

Specific leaf area is modulated by nitrogen via changes in primary metabolism and parenchymal thickness in pepper.

Nitrogen promotes changes in SLA through metabolism and anatomical traits in Capsicum plants. Specific leaf area (SLA) is a key trait influencing light interception and light use efficiency that often impacts plant growth and production. SLA is a key trait explaining growth variations of plant species under different environments. Both light and nitrogen (N) supply are important determinants of SLA. To better understand the effect of irradiance level and N on SLA in Capsicum chinense, we evaluated primary metabolites and morphological traits of two commercial cultivars (Biquinho and Habanero) in response to changes in both parameters. Both genotypes showed increased SLA with shading, and a decrease in SLA in response to increased N supply, however, with Habanero showing a stable SLA in the range of N deficiency to sufficient N doses. Correlation analyses indicated that decreased SLA in response to higher N supply was mediated by altered amino acids, protein, and starch levels, influencing leaf density. Moreover, in the range of moderate N deficiency to N sufficiency, both genotypes exhibited differences in SLA response, with Biquinho and Habanero displaying alterations on palisade and spongy parenchyma, respectively. Altogether, the results suggest that SLA responses to N supply are modulated by the balance between certain metabolites content and genotype-dependent changes in the parenchyma cells influencing leaf thickness and density.

Variation in leaf xeromorphism in the desert palm genus Washingtonia (Arecaceae)

Washingtonia palms occur scattered in oases and canyons of the larger Sonoran Desert from lat. 24° to lat. 34° N. Northern oases have an arid temperate climate while those in the south experience seasonally dry, tropical conditions. A marked latitudinal cline in morphological characters has been described within the genus. We hypothesized that aridity-adapted leaf traits in Washingtonia palms, such as amphistomaty and isolaterality, could exhibit a predictable trend along the 1300-km-long gradient, allowing us to test whether the evolution of leaf xeromorphism is correlated with environmental aridity.We took measurements of anatomical and functional traits of leaves in 16 oases spanning the whole distributional range of the genus in Mexico and the US. Using regression models, we examined the response of specific leaf area, leaf greenness, ẟ13C, stomatal size, and stomatal density to latitude, site, and landform. We used Principal Components Analysis and correlation matrices to identify bioclimatic variables that might be playing a role in the observed latitudinal patterns.Palms at northern sites have waxy, glaucous, thick, leaves and exhibit xeromorphic traits such as amphistomaty and isolaterality. Palms at more tropical sites have glossy green, thin leaves that do not show xeromorphic traits.Leaf xeromorphism, a morphological and physiological syndrome in Washingtonia palms, increases with aridity.

Variability among Young Table Grape Cultivars in Response to Water Deficit and Water Use Efficiency

Climate change will lead to higher frequencies and durations of water limitations during the growing season, which may affect table grape yield. The aim of this experiment was to determine the variability among 3-year old table grape cultivars under the influence of prolonged water deficit during fruit development on gas exchange, growth, and water use efficiency. Six own rooted, potted table grape cultivars (cv. ‘Muscat Bleu’, ‘Fanny’, ‘Nero’, ‘Palatina’, ‘Crimson Seedless’ and ‘Thompson Seedless’) were subjected to three water deficit treatments (Control treatment with daily irrigation to 75% of available water capacity (AWC), moderate (50% AWC), and severe water deficit treatment (25% AWC)) for three consecutive years during vegetative growth/fruit development. Water deficit reduced assimilation, stomatal conductance, and transpiration, and increased water use efficiencies (WUE) with severity of water limitation. While leaf area and number of leaves were not affected by treatments in any of the tested cultivars, the response of specific leaf area to water deficit depended on the cultivar. Plant dry mass decreased with increasing water limitation. Overall, high variability of cultivars to gas exchange and water use efficiencies in response to water limitation was observed. ’Palatina’ was the cultivar having a high productivity (high net assimilation) and low water use (low stomatal conductance) and the cultivar ‘Fanny’ was characterized by the highest amount of total annual dry mass as well as the highest total dry mass production per water supplied during the experiment (WUEDM). Hence, ‘Fanny’ and ‘Palatina’ have shown to be cultivars able to cope with water limiting conditions and should be extensively tested in further studies.

Intraspecific trait variation in grassland plant communities along urban-rural gradients

Trait-based approaches have been successfully used to demonstrate how the modified ecological conditions within urban areas filter plant species within plant communities. However, there is growing evidence that trait measurement in situ may improve knowledge of the ecological mechanisms underlying such filtering processes. This study aimed to determine the relative contribution of inter- and intraspecific trait variation in explaining the influence of urban-rural gradients on grassland plant communities. Twenty-one stations were sampled along an urban-rural gradient in two French cities. Three functional traits (specific leaf area, maximum height and phenology), chosen to represent general adaptive strategies of plants, were measured on the 26 most abundant grassland plant species. By decomposing the community-level variance of these traits into species turnover, intraspecific trait variability and covariation, we showed how important it may be to take field measurements into account when studying trait distributions in urban ecology. High intraspecific variability may reinforce trait selection effects, for example by favoring both taller species and populations of taller individuals in urban areas in comparison with rural contexts. Advanced phenology at community-level was influenced by early flowering for almost all urban populations of each species while Specific Leaf Area responses were inconsistent. Because trait distributions and ecosystem functions are closely linked, we suggest that it is now important to develop trait-based approaches at community-level, including both intra- and inter-specific trait variability, in order to improve our knowledge of ecological processes operating in urban areas.

Specific responses of sap flux and leaf functional traits to simulated canopy and understory nitrogen additions in a deciduous broadleaf forest.

To investigate the effects of atmospheric nitrogen (N) deposition on water use characteristics and leaf traits of trees, we performed canopy (C50) and understory (U50) N additions as NH4NO3 of 50 kg N ha-1 year-1 in a deciduous broadleaf forest of central China. We measured xylem sap flux, crown area:sapwood area ratio (Ca:As), specific leaf area (SLA), mass-based leaf nitrogen content (Nmass) and leaf carbon isotope ratio (δ13C) of Liquidambar formosana Hance, Quercus acutissima Carruth. and Quercus variabilis Blume. Functional traits under different N addition treatments and their responses among tree species were compared and the relationship between xylem sap flux and leaf functional traits under N additions were explored. Results showed that under U50 sap-flux density of xylem significantly decreased for three tree species. But the effect of C50 on sap flux was species-specific. The decrease of sap-flux density with N additions might be caused by the increased Ca/As. δ13C remained constant among different N addition treatments. The responses of SLA and Nmass to N additions were species- and N addition approaches-specific. The correlation of xylem sap flux with leaf traits was not found. Our findings indicate that the effects of canopy N addition on xylem sap flux and leaf functional traits were species-specific and it is necessary to employ canopy N addition for exploring the real responses of forest ecosystems to climate changes in the future researches.

Changes in specific leaf area of dominant plants in temperate grasslands along a 2500-km transect in northern China

Specific leaf area (SLA) is a key trait with great ecological importance as it correlates with whole plant growth. We aimed to investigate how SLA varies with environmental factors at a geographical scale in temperate grasslands. We measured SLA and mass-based leaf nitrogen content (Nmass) of four dominant plant genera along a 2500 km climatic gradient in northern China grassland, and correlated SLA with mean annual precipitation (MAP), mean annual temperature (MAT), soil nitrogen concentration (soil N), soil C:N and Nmass. Climate accounts much more for SLA variation than soil variables for Stipa, Cleistogens and Carex. SLA of Stipa is negatively associated with MAP and soil N, while positively with MAT, but Cleistogenes and Carex show the opposite. For Leymus, soil N promotes SLA and accounts for largest fraction of SLA variation. Overall, SLA was positively correlated with Nmass in semi-arid regions, but not significant in arid regions. The genus-dependent responses of SLA may have consequences on ecosystem functioning, thus may help to predict the community composition and ecosystem functions under future climate scenario. The finding of SLA-Nmass trade-off and its susceptibility to precipitation will advance our understanding on plant resource use strategies.

Effects of extreme drought on specific leaf area of grassland species: A meta-analysis of experimental studies in temperate and sub-Mediterranean systems.

Here, we conducted a meta-analysis of experimental drought manipulation studies using rainout shelters in five sites of natural grassland ecosystems of Europe. The single studies assess the effects of extreme drought on the intraspecific variation of the specific leaf area (SLA), a proxy of plant growth. We evaluate and compare the effect size of the SLA response for the functional groups of forbs and grasses in temperate and sub-Mediterranean systems. We hypothesized that the functional groups of grasses and forbs from temperate grassland systems have different strategies in short-term drought response, measured as adjustment of SLA, with SLA-reduction in grasses and SLA-maintenance in forbs. Second, we hypothesized that grasses and forbs from sub-Mediterranean systems do not differ in their drought response as both groups maintain their SLA. We found a significant decrease of SLA in grasses of the temperate systems in response to drought while SLA of forbs showed no significant response. Lower SLA is associated with enhanced water-use efficiency under water stress and thus can be seen as a strategy of phenotypic adjustment. By contrast, in the sub-Mediterranean systems, grasses significantly increased their SLA in the drought treatment. This result points towards a better growth performance of these grasses, which is most likely related to their strategy to allocate resources to belowground parts. The observed SLA reduction of forbs is most likely a direct drought response given that competitive effect of grasses is unlikely due to the scanty vegetation cover. We point out that phenotypic adjustment is an important driver of short-term functional plant response to climatic extremes such as drought. Differential reactions of functional groups have to be interpreted against the background ofthe group's evolutionary configuration that can differ between climatic zones.

Linking Changes to Intraspecific Trait Diversity to Community Functional Diversity and Biomass in Response to Snow and Nitrogen Addition Within an Inner Mongolian Grassland.

In recent years, both the intraspecific and interspecific functional diversity (FD) of plant communities have been studied with new approaches to improve an understanding about the mechanisms underlying plant species coexistence. Yet, little is known about how global change drivers will impact intraspecific FD and trait overlap among species, and in particular how this may scale to impacts on community level FD and ecosystem functioning. To address this uncertainty, we assessed the direct and indirect responses of specific leaf area (SLA) among both dominant annual and subordinate perennial species to the independent and interactive effects of nitrogen and snow addition within the Inner Mongnolian steppe. More specifically, we investigated the consequences for these responses on plant community FD, trait overlap and biomass. Nitrogen addition increased the biomass of the dominant annual species and as a result increased total community biomass. This occurred despite concurrent decreases in the biomass of subordinate perennial species. Nitrogen addition also increased intraspecific FD and trait overlap of both annual species and perennial species, and consequently increased the degree of trait overlap in SLA at the community level. However, snow addition did not significantly impact intraspecific FD and trait overlap of SLA for perennial species, but increased intraspecific FD and trait overlap of annual species, of which scaled to changes in community level FD. We found that the responses of the dominant annual species to nitrogen and snow additions were generally more sensitive than the subordinate perennial species within the inner Mongolian grassland communities of our study. As a consequence of this sensitivity, the responses of the dominant species largely drove impacts to community FD, trait overlap and community biomass. In total, our study demonstrates that the responses of dominant species in a community to environmental change may drive the initial trajectories of change to community FD and functioning.

河北固城夏玉米比叶面积对水分梯度的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 河北固城夏玉米比叶面积对水分梯度的响应 DOI: 10.5846/stxb201701130104 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家行业专项（GYHY201306038） Response of specific leaf area of summer maize to water gradient in Hebei Gucheng Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:基于河北固城农试站2013-2015年夏玉米田间水分控制试验，研究了夏玉米比叶面积（SLA）随发育期的变化趋势，并分主要发育时段探讨了SLA与水分梯度的定量关系。结果表明，从七叶期开始夏玉米SLA随发育进程的推进总体呈下降趋势，七叶期至成熟期SLA变化范围平均为14.6-34.9m2/kg。尽管干旱胁迫会明显降低夏玉米地上绿叶面积和干重，但却使SLA表现出"补偿性"增大，用于弥补干旱胁迫导致光合产物不足引起的叶片扩张乏力。夏玉米出苗-拔节期、抽雄-成熟期土壤相对湿度（θ）每降低1%，SLA分别上升0.45m2/kg和0.07m2/kg，表明出苗-拔节期夏玉米对干旱的"适应"能力更强；而拔节-抽雄期SLA与θ的关系较为复杂，表现为先增大后减小的抛物线型。 Abstract:Specific leaf area (SLA), the ratio of green leaf area to its dry weight, is one of the most important parameters of leaf function evaluation, which could reflect resource utilization ability and adaptability to different environments of plants. Recently, many preliminary conclusions have been reported about the variation trend of maize SLA under drought stress, but most of them were qualitative descriptions and lacked quantitative analysis. In this study, based on water-control field experiments in Hebei Gucheng, China from 2013 to 2015, the variation trends of summer maize SLA on major developmental stages were investigated, and the quantitative relationships between SLA and soil moisture on different developmental stages were also established. As the experiment designed, 3 major developmental stages of summer maize (emergence to jointing, jointing to tasseling, tasseling to maturity), as well as[(emergence to jointing) + (jointing to tasseling)],[(emergence to jointing) + (tasseling to maturity)], and[(jointing to tasseling) + (tasseling to maturity)], were all water controlled in turn. The experiment was set with 4 water-control treatments and 1 contrast treatment, in which the soil relative moisture θ was ≤ 40% (T1), 40%-60% (T2), 60%-80% (T3), >80% (T4), and natural precipitation (T5), respectively. Results showed that the summer maize SLA presented a declining trend during the entire growing season, with an averaged variation range of 14.6-34.9m2/kg. Specifically, the SLA reached maximum value at seven-leaf stage (34.9m2/kg), declined rapidly at jointing stage (23.4m2/kg), decreased slightly at the tasseling stage (18.1-18.8m2/kg), and was the lowest at the maturity stage with an average of 14.6m2/kg. Experimental data showed that drought stress could significantly decrease the leaf area and dry weight of summer maize, but the SLA showed a "compensatory" larger value in order to compensate for the leaf expansion fatigue caused by insufficient photosynthates. The summer maize SLA had a significant linear negative correlation with soil moisture from the emergence to jointing and tasseling to maturity stages, with increase of 0.45m2/kg (emergence to jointing stage) and 0.07m2/kg (tasseling to maturity stage) when the soil relative moisture decreased by 1%, indicating that the summer maize had more adaptation to drought during emergence to jointing stage. However, the relationship between SLA and soil moisture on the jointing to tasseling stage was more complex; it first increased and then decreased with a parabola shape. 参考文献 相似文献 引证文献

Leaf trait associations with environmental variation in the wide‐ranging shrub Dodonaea viscosa subsp. angustissima (Sapindaceae)

Intra-species variation in specific leaf area (SLA) and leaf area (LA) provides mechanistic insight into the persistence and function of plants, including their likely success under climate change and their suitability for revegetation. We measured SLA and LA in 101 Australian populations of the perennial shrub Dodonaea viscosa (L.) Jacq. subsp. angustissima (narrow-leaf hop-bush) (Sapindaceae). Populations were located across about a 1000 km north–south gradient, with climate grading from arid desert to mesic Mediterranean. We also measured leaves from 11 populations across an elevational gradient (300–800 m asl), where aridity and temperature decrease with elevation. We used regression and principal component analyses to relate leaf traits to the abiotic environment. SLA displayed clinal variation, increasing from north to south and correlated with latitude and the first principal component of joint environmental variables. Both SLA and LA correlated positively with most climatic and edaphic variables. Across latitude, LA showed more variability than SLA. Changes in leaf density and thickness may have caused the relative stability of SLA. Only LA decreased with elevation. The absence of a SLA response to elevation could be a consequence of abiotic conditions that favour low SLA at both ends of the elevational gradient. We demonstrated that the widely distributed narrow-leaf hop-bush shows considerable variability in LA and SLA, which allows it to persist in a broad environmental envelope. As this shrub is widely used for revegetation in Australia, South America and the Asia-Pacific region, our results are consistent with the notion that seed used to revegetate mesic environments could be sourced from more arid areas to increase seed suitability to future climate change.

Light availability drives tree seedling success in a subtropical coastal dune forest in South Africa

In subtropical coastal dune forests of South Africa, the microenvironment of tree seedlings is largely influenced by a pervasive understorey woody herb, Isoglossa woodii. We examined whether the additional shading by I. woodii explains the competitive response of tree seedlings from these forests. Seedlings of four common mid- to late-successional tree species (Diospyros natalensis, Euclea racemosa, Sideroxylon inerme and Apodytes dimidiata) were grown at three densities of I. woodii in a common garden experiment under greenhouse conditions. The seedlings were grown at 1.6% and 13.5% of full sunlight and supplied with 1% and 10% nitrogen in half-strength Hoagland's nutrient solution. Total biomass and biomass allocation parameters were used to measure the competitive response of the seedlings. Seedlings attained maximum biomass at high light and high nutrient levels and showed species- and light-specific responses to biomass of I. woodii neighbours. Seedlings' allocation to roots increased with increasing light levels but decreased at higher nutrient levels. The leaf mass fraction (LMF) response to light and nutrient levels was opposite to that shown by root allocation. Specific leaf area (SLA) and leaf area ratio (LAR) decreased with increasing light conditions but were not responsive to manipulation of nutrients. The presence of I. woodii neighbours reduced LMF whilst the responses of SLA to neighbours depended on the light level and species. Leaf trait responses to manipulation of light conditions, I. woodii neighbour density and soil nutrient concentration are complex but overall demonstrate an overwhelming role of light in influencing seedling establishment in coastal dune forests. The competitive response of these seedlings to low irradiance reiterates the notion of phenotypic clustering at the seedling stage amongst shade tolerant tree species, which promotes seedling persistence and gradual transition into the tree layer. Our results highlight the role of additional understorey shading by the herb stratum in influencing tree recruitment dynamics and ultimately tree community structure in many of Africa's tropical lowland forests.

Specific leaf area responses to environmental gradients through space and time

Plant communities can respond to environmental changes by altering their species composition and by individuals (within species) adjusting their physiology. These responses can be captured by measuring key functional traits among and within species along important environmental gradients. Some anthropogenic changes (such as fertilizer runoff) are known to induce distinct community responses, but rarely have responses across natural and anthropogenic gradients been compared in the same system. In this study, we used comprehensive specific leaf area (SLA) data from a diverse Australian annual plant system to examine how individual species and whole communities respond to natural and anthropogenic gradients, and to climatically different growing seasons. We also investigated the influence of different leaf-sampling strategies on community-level results. Many species had similar mean SLA values but differed in SLA responses to spatial and temporal environmental variation. At the community scale, we identified distinct SLA responses to natural and anthropogenic gradients. Along anthropogenic gradients, increased mean SLA, coupled with SLA convergence, revealed evidence of competitive exclusion. This was further supported by the dominance of species turnover (vs. intraspecific variation) along these gradients. We also revealed strong temporal changes in SLA distributions in response to increasing growing-season precipitation. These climate-driven changes highlight differences among co-occurring species in their adaptive capacity to exploit abundant water resources during favorable seasons, differences that are likely to be important for species coexistence in this system. In relation to leaf-sampling strategies, we found that using leaves from a climatically different growing season can lead to misleading conclusions at the community scale.

A functional comparative approach to facilitation and its context dependence

Summary Our ability to generalize about broad patterns and outcomes of competitive interactions among plants has improved from a better understanding of functional traits. Facilitative interactions among plants also exhibit strong trait‐based patterns; however, very little empirical research has addressed the trait basis of different facilitative mechanisms or the applicability of traditionally defined functional strategies to facilitation. We present a series of predictions regarding the trait basis of a variety of facilitative mechanisms based on empirical patterns of trait responses to environmental filters and knowledge of plant–environment feedbacks. Using a leaf‐height‐seed framework to predict plant responses to facilitative effects of neighbours, we identify two categories of facilitative mechanisms based on similar predicted responses of specific leaf area (SLA), height and seed size: (i) facilitation of low‐SLA, large‐seeded and tall plants in environments typified by periodically unfavourable conditions; and (ii) facilitation of high‐SLA, small‐seeded and tall plants in persistently severe environments. We suggest that facilitation related to herbivory will be idiosyncratic with respect to these functional traits. Competition for limiting resources is predicted to reinforce trait‐based responses to facilitation in periodically severe environments, particularly under light competition, but to offset facilitative effects to some degree in persistently severe environments. Thus, biotic interactions may have stronger consequences for shifts in trait distributions in environments typified by disturbance, pulsed soil moisture and short growing seasons limited by low temperatures. Facilitative effects, in addition to facilitative responses, may also be regulated by functional traits, but there is much less empirical evidence for links between functional traits and ameliorative effects on the environment. However, we predict that leaf area index or other integrative traits related to canopy density are likely to be important effect traits for most facilitative mechanisms and should be integrated into more trait‐screening programs. Based on the exceptional contribution that trait‐based approaches have made for understanding other interactions, we suggest that taking a functional comparative approach to facilitation is an opportunity to improve our ability to identify general patterns and consequences of positive interactions.

Alien plant species with a wider global distribution are better able to capitalize on increased resource availability

• A high ability of alien plant species to capitalize on increases in resource availability has been suggested as an explanation for being globally successful. Here, we tested this hypothesis meta-analytically using existing data from experiments manipulating plant resources (light, water and nutrients). • From these studies we extracted the response to resource increase of biomass, as an indicator of plant performance, and the responses of two traits related to resource capture: root : shoot ratio and specific leaf area (SLA). For 211 species recorded in the Global Compendium of Weeds, we assessed the relationship between effect sizes from such studies and the number of global regions where a species was established. • We found that globally widespread species exhibited greater biomass responses to increases in resources overall, compared to less widespread species. Root : shoot ratio and SLA responses to increased resource availability were not related to species global distribution. • In general, globally widespread alien plant species were better able to capitalize on increased availability of resources, through achieving increased growth and biomass accumulation, while greater plasticity of key resource-capture traits per se did not appear to be related to greater success.

Succession‐induced trait shifts across a wide range of NW European ecosystems are driven by light and modulated by initial abiotic conditions

Summary1. For truly predictive community ecology, it is essential to understand the interplay between species traits, their environment and their impacts on the composition of plant communities. These interactions are increasingly understood for various environmental drivers, but our understanding of how traits, in general, change during succession is still modest. We hypothesize that (initial) abiotic conditions other than light drive the successional dynamics of other traits. The idea that different initial abiotic conditions lead to different trait trajectories during succession was predicted long ago but has never been tested for traits.2. In this study, we compared the successional (decades to centuries) trait trajectories of 19 ecosystem types in low‐altitude NW Europe using a database including >4700 plots. We tested which traits (out of a total of 12, including those associated with light competition strategies) show consistent shifts across ecosystems. Additionally, we investigated, through a novel partitioning of trait differences (using partial principal component analyses), whether abiotic factors can explain trait shifts that occur over and above light‐induced trait shifts.3. We show that canopy height, woodiness, leaf size and seed mass increase, and flowering onset and flowering duration decrease consistently with succession across ecosystems, while leaf economic traits and life span showed a mixed response during succession. Accounting for the effect of height revealed that the initial and prevailing abiotic conditions – particularly soil moisture – co‐determine trait shifts during succession. Therefore, different initial starting conditions may lead to different trajectories in trait space, most notably due to the differential response of specific leaf area (SLA), leaf nitrogen content and life span. For example, SLA decreases in seres that become drier over time (initially very wet), while it increases in seres that become wetter over time (initially very dry).4. Synthesis. Our novel approach of partitioning successional trait shifts between the influence of competition for light and other abiotic factors showed that trajectories of ecosystems through trait space can be explained by a combination of the two: a universal response to changing light availability and a specific response depending on initial abiotic conditions.

A method to construct dose–response curves for a wide range of environmental factors and plant traits by means of a meta-analysis of phenotypic data

In the past, biologists have characterized the responses of a wide range of plant species to their environment. As a result, phenotypic data from hundreds of experiments are publicly available now. Unfortunately, this information is not structured in a way that enables quantitative and comparative analyses. We aim to fill this gap by building a large database which currently contains data on 1000 experiments and 800 species. This paper presents methodology to generalize across different experiments and species, taking the response of specific leaf area (SLA; leaf area:leaf mass ratio) to irradiance as an example. We show how to construct and quantify a normalized mean light-response curve, and subsequently test whether there are systematic differences in the form of the curve between contrasting subgroups of species. This meta-analysis is then extended to a range of other environmental factors important for plant growth as well as other phenotypic traits, using >5300 mean values. The present approach, which we refer to as 'meta-phenomics', represents a valuable tool in understanding the integrated response of plants to their environment and could serve as a benchmark for future phenotyping efforts as well as for modelling global change effects on both wild species and crops.

Environmental and developmental controls on specific leaf area are little modified by leaf allometry

Summary 1. Recent work shows that large leaves tend to require higher biomass investments per unit leaf area than small leaves. As a consequence, specific leaf area (SLA), which is a focus trait for a bulk of physiological and ecological research programs, is dependent on leaf size variation. Here, we address whether size dependency alters the outcome of research dealing with SLA responses to environmental or developmental change. 2. We compiled lamina mass ( M ) and surface area ( A ) data for 2158 leaves of 26 species, coming from studies investigating the reaction of SLA to variation in rainfall, growth‐season length, light intensity, atmospheric CO 2 , fire frequency, type of branch and leaf and plant age. We fitted the function M = α A β to the data of each experimental situation separately, and implemented a method to split SLA response as measured in the original study (SLA ∆ m ) into response due to leaf size dependency (SLA ∆ a ), and response due to treatment effects, after controlling for leaf size dependency (SLA ∆ t ). 3. The sign of the reaction did not differ between SLA ∆ m and SLA ∆ t . However, the magnitude of that response changed for most contrasts, though in variable ways. 4. Conclusions of past experiments hold, for the most part, after re-analysis including size dependency. However, given the large heterogeneity found here, we advise that future work investigating SLA be prepared to account for leaf size dependency when the factors under focus are suspected to alter leaf size.