\n\nEnvironmental variables that positively affect one aspect of plant fitness, may have no effect, or even negatively affect some other component of fitness.

Average responses of forest foliar traits to elevation are well understood, but far less is known about trait distributional responses to elevation at multiple ecological scales. This limits our understanding of the ecological scales at which trait variation occurs in response to environmental drivers and change. We analyzed and compared multiple canopy foliar trait distributions using field sampling and airborne imaging spectroscopy along an Andes-to-Amazon elevation gradient. Field-estimated traits were generated from three community-weighting methods, and remotely sensed estimates of traits were made at three scales defined by sampling grain size and ecological extent. Field and remote sensing approaches revealed increases in average leaf mass per unit area (LMA), water, nonstructural carbohydrates (NSCs) and polyphenols with increasing elevation. Foliar nutrients and photosynthetic pigments displayed little to no elevation trend. Sample weighting approaches had little impact on field-estimated trait responses to elevation. Plot representativeness of trait distributions at landscape scales decreased with increasing elevation. Remote sensing indicated elevation-dependent increases in trait variance and distributional skew. Multiscale invariance of LMA, leaf water and NSC mark these traits as candidates for tracking forest responses to changing climate. Trait-based ecological studies can be greatly enhanced with multiscale studies made possible by imaging spectroscopy.© 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

A key trait used in canopy and ecosystem function modeling, leaf mass per area (LMA), is influenced by changes in both leaf thickness and leaf density (LMA = Thickness × Density). In tall trees, LMA is understood to increase with height through two primary mechanisms: (i) increasing palisade layer thickness (and thus leaf thickness) in response to light and/or (ii) reduced cell expansion and intercellular air space in response to hydrostatic constraints, leading to increased leaf density. Our objective was to investigate within-canopy gradients in leaf anatomical traits in order to understand environmental factors that influence leaf morphology in a sugar maple (Acer saccharum Marshall) forest canopy. We teased apart the effects of light and height on anatomical traits by sampling at exposed and closed canopies that had different light conditions at similar heights. As expected, palisade layer thickness responded strongly to cumulative light exposure. Mesophyll porosity, however, was weakly and negatively correlated with light and height (i.e., hydrostatic gradients). Reduced mesophyll porosity was not likely caused by limitations on cell expansion; in fact, epidermal cell width increased with height. Palisade layer thickness was better related to LMA, leaf density and leaf thickness than was mesophyll porosity. Vein diameter and fraction of vascular tissue also increased with height and LMA, density and thickness, revealing that greater investment in vascular and support tissue may be a third mechanism for increased LMA with height. Overall, decreasing mesophyll porosity with height was likely due to palisade cells expanding into the available air space and also greater investments in vascular and support tissue, rather than a reduction of cell expansion due to hydrostatic constraints. Our results provide evidence that light influences both palisade layer thickness and mesophyll porosity and indicate that hydrostatic gradients influence leaf vascular and support tissues in mature Acer saccharum trees.© The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

In temperate deciduous forests, vertical gradients in leaf mass per area (LMA) and area-based leaf nitrogen (Narea) are strongly controlled by gradients in light availability. While there is evidence that hydrostatic constraints on leaf development may diminish LMA and Narea responses to light, inherent differences among tree species may also influence leaf developmental and morphological response to light. We investigated vertical gradients in LMA, Narea and leaf carbon isotope composition (δ13C) for three temperate deciduous species (Carpinus caroliniana Walter, Fagus grandifolia Ehrh., Liriodendron tulipifera L.) that differed in growth strategy (e.g., indeterminate and determinate growth), shade tolerance and leaf area to sapwood ratio (Al:As). Leaves were sampled across a broad range of light conditions within three vertical layers of tree crowns to maximize variation in light availability at each height and to minimize collinearity between light and height. All species displayed similar responses to light with respect to Narea and δ13C, but not for LMA. Light was more important for gradients in LMA for the shade-tolerant (C. caroliniana) and -intolerant (L. tulipifera) species with indeterminate growth, and height (e.g., hydrostatic gradients) and light were equally important for the shade-tolerant (F. grandifolia) species with determinate growth. Fagus grandifolia had a higher morphological plasticity in response to light, which may offer a competitive advantage in occupying a broader range of light conditions throughout the canopy. Differences in responses to light and height for the taller tree species, L. tulipifera and F. grandifolia, may be attributed to differences in growth strategy or Al:As, which may alter morphological and functional responses to light availability. While height was important in F. grandifolia, height was no more robust in predicting LMA than light in any of the species, confirming the strong role of light availability in determining LMA for temperate deciduous species.© The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

There is growing recognition that classifying terrestrial plant species on the basis of their function (into 'functional types') rather than their higher taxonomic identity, is a promising way forward for tackling important ecological questions at the scale of ecosystems, landscapes or biomes. These questions include those on vegetation responses to and vegetation effects on, environmental changes (e.g. changes in climate, atmospheric chemistry, land use or other disturbances). There is also growing consensus about a shortlist of plant traits that should underlie such functional plant classifications, because they have strong predictive power of important ecosystem responses to environmental change and/or they themselves have strong impacts on ecosystem processes. The most favoured traits are those that are also relatively easy and inexpensive to measure for large numbers of plant species. Large international research efforts, promoted by the IGBP–GCTE Programme, are underway to screen predominant plant species in various ecosystems and biomes worldwide for such traits. This paper provides an international methodological protocol aimed at standardising this research effort, based on consensus among a broad group of scientists in this field. It features a practical handbook with step-by-step recipes, with relatively brief information about the ecological context, for 28 functional traits recognised as critical for tackling large-scale ecological questions.

Optimizing crops to improve light absorption and CO assimilation throughout the canopy is a proposed strategy to increase yield and meet the needs of a growing population by 2050. Globally, the greatest population increase is expected to occur in Sub-Saharan Africa where large yield gaps currently persist; therefore, it is crucial to develop high-yielding crops adapted to this region. In this study, we screened 50 cowpea ( (L.) Walp) genotypes from the multi-parent advanced generation inter-cross (MAGIC) population for canopy architectural traits, canopy photosynthesis, and water-use efficiency using a canopy gas exchange chamber in order to improve our understanding of the relationships among those traits. Canopy architecture contributed to 38.6% of the variance observed in canopy photosynthesis. The results suggest that the light environment within the canopy was a limiting factor for canopy CO assimilation. Traits favoring greater exposure of leaf area to light such as the width of the canopy relative to the total leaf area were associated with greater canopy photosynthesis, especially in canopies with high biomass. Canopy water-use efficiency was highly determined by canopy photosynthetic activity and therefore canopy architecture, which indicates that optimizing the canopy will also contribute to improving canopy water-use efficiency. We discuss different breeding strategies for future programs aimed at the improvement of cowpea yield for the Sub-Saharan African region. We show that breeding for high biomass will not optimize canopy CO assimilation and suggest that selection should include multiple canopy traits to improve light penetration.© 2020 The Authors. Food and Energy Security published by John Wiley & Sons Ltd on behalf of Association of Applied Biologists.

Leaf functional traits are strongly tied to growth strategies and ecological processes across species, but few efforts have linked intraspecific trait variation to performance across ontogenetic and environmental gradients. Plants are believed to shift towards more resource-conservative traits in stressful environments and as they age. However, uncertainty as to how intraspecific trait variation aligns with plant age and performance in the context of environmental variation may limit our ability to use traits to infer ecological processes at larger scales.

Ferns that evolved from 400 million years ago show various functional traits and ecological strategies in extant species, over 80% of which belong to the youngest order Polypodiales. How the functional traits and strategies of ferns have changed during their evolutionary history remains unexplored. Here, we measured functional traits that are sensitive to environmental light and water availability in 345 fern species across fern phylogeny, and reconstructed their evolutionary histories. We found that ferns, mainly Polypodiales, have developed diversified functional traits in response to forest environments. Terrestrial species, especially Thelypteridaceae and Athyriaceae in eupolypods II, since the late Jurassic period, have shown decreased leaf mass per area (LMA) and area-based leaf nitrogen (N_area), but increased mass-based leaf nitrogen (N_mass) compared with early-derived polypods. Epiphytic species, mainly those in Polypodiaceae, have shown reductions in N_mass and individual leaf area (Area) since the late Cretaceous period. The adaption of functional traits of Polypodiales to forest environment may have played a crucial role in fern radiation since the late Jurassic period. Integrative analysis of functional traits, especially numerical ones, may shed new light on plant evolution.

Photosynthetic light acclimation of leaves can result from (i) changes in mass-based leaf nitrogen concentration, Nm, (ii) changes in leaf mass:area ratio, Ma, and (iii) partitioning of total leaf nitrogen among different pools of the photosynthetic machinery. We studied variations in Nm and Ma within the crowns of two peach (Prunus persica L. Batsch) trees grown in an orchard in Portugal, and one peach tree grown in an orchard in France. Each crown was digitized and a 3-D radiation transfer model was used to quantify the intra-crown variations in time-integrated leaf irradiance, <PARi>. Nitrogen concentration, leaf mass:area ratio, chlorophyll concentration, and photosynthetic capacity were also measured on leaves sampled on five additional peach trees in the orchard in Portugal. The data were used to compute the coefficients of leaf nitrogen partitioning among carboxylation, bioenergetics, and light harvesting pools. Leaf mass:area ratio and area-based leaf nitrogen concentration, Na, were nonlinearly related to <PARi>, and photosynthetic capacity was linearly related to Na. Photosynthetic light acclimation resulted mainly from changes in Ma and leaf nitrogen partitioning, and to a lesser extent from changes in Nm. This behavior contrasts with photosynthetic light acclimation observed in other tree species like walnut (Juglans regia L.) in which acclimation results primarily from changes in Ma.

Acclimation to ambient light has been assumed to be the principal cause of vertical gradients in leaf nitrogen, foliar morphology, and related traits in forest canopies. We examined the relative role of crown exposure, damage, and reproduction as correlates of vertical gradients in shoot and needle morphology, anatomy, and chemistry in a ~120-year-old stand of Pinus strobus L. (eastern white pine) in central Ontario. Internodes at the top of trees were longer, wider, and produced more fascicles, but had lower fascicle survivorship than lower-canopy shoots. Needles on upper-canopy shoots also had higher allocation to resin ducts than mid- or lower-canopy needles, contained less nitrogen on a mass basis, and showed a higher leaf mass per area, C/N ratio, and chlorophyll a/b ratio. Tree-to-tree variation among the 26 trees measured traits was high, owing, in part, to differences in crown damage and reproductive status. Crown damage was associated with reduced leaf mass per area and other traits associated with shade acclimation, while high cone production was associated with reduced leaf nitrogen and chlorophyll in the upper canopy. Our results suggest that factors other than light acclimation play an important role in determining vertical gradients in foliar morphology, nitrogen, and leaf production in forest canopies.

Combining palaeontological and neontological data offers a unique opportunity to investigate the relative roles of biotic and abiotic controls of species diversification, and the importance of origination versus extinction in driving evolutionary dynamics. Ferns comprise a major terrestrial plant radiation with an extensive evolutionary history providing a wealth of modern and fossil data for modelling environmental drivers of diversification. Here we develop a novel Bayesian model to simultaneously estimate correlations between diversification dynamics and multiple environmental trajectories. We estimate the impact of different factors on fern diversification over the past 400 million years by analysing a comprehensive dataset of fossil occurrences and complement these findings by analysing a large molecular phylogeny. We show that origination and extinction rates are governed by fundamentally different processes: originations depend on within-group diversity but are largely unaffected by environmental changes, whereas extinctions are strongly affected by external factors such as climate and geology. Our results indicate that the prime driver of fern diversity dynamics is environmentally driven extinction, with origination being an opportunistic response to diminishing ecospace occupancy.

建立植物功能性状与群落动态之间的关联是功能生态学的核心问题之一。本文基于鼎湖山1.44 ha塔吊样地的两次调查数据, 通过采集样地内所有4,142株个体的6种植物功能性状, 对比分析了个体水平植物功能性状和物种水平功能性状均值对不同垂直层次(灌木层、亚冠层和林冠层)个体生长的影响差异。首先, 分析了不同垂直层次下各植物功能性状的变化趋势; 其次, 计算了不同垂直层次下各植物功能性状的种内和种间变异水平; 最后, 运用结构方程模型探讨了植物功能性状、光竞争以及地下竞争对不同垂直层次树木生长的影响。结果表明: (1)不同垂直层次下的植物功能性状表现出明显的分异, 由灌木层至林冠层, 叶面积、比叶面积和能量供求关系指数显著降低, 而叶片厚度和叶片干物质含量显著升高; (2)不同垂直层次下植物功能性状的种间变异均大于种内变异, 且林冠层的种内功能性状变异均大于灌木层和亚冠层; (3)基于个体水平植物功能性状的结构方程模型较物种水平功能性状均值对生长具有更高的解释程度, 且个体水平植物功能性状的引入更有利于提高对灌木层个体生长的预测能力; (4)光竞争和地下竞争主要通过影响功能性状间接影响植物生长。由灌木层至林冠层, 同种间的相互作用逐渐减弱, 异种间的相互作用逐渐增强。综上, 将个体水平植物功能性状纳入分析有助于更好地理解群落的结构和动态。

The plant economics spectrum theory provides a useful framework to examine plant strategies by integrating the co-ordination of plant functional traits along a resource acquisition-conservation trade-off axis. Empirical evidence for this theory has been widely observed for seed plants (Spermatophyta). However, whether this theory can be applied to ferns (Pteridophyta), a ubiquitous and ancient group of vascular plants, has rarely been evaluated so far.We measured 11 pairs of plant functional traits on leaves and fine roots (diameter <2 mm) on 12 coexisting fern species in a sub-tropical forest. Litterbags of leaves and roots were placed in situ and exposed for 586 d to measure decomposition rates. The variation of traits across species and the co-ordination among traits within and between plant organs were analysed. Finally, the influence of the traits on decomposition rates were explored.Most leaf and root traits displayed high cross-species variation, and were aligned along a major resource acquisition-conservation trade-off axis. Many fern traits co-varied between leaves and fine roots, suggesting co-ordinated responses between above- and below-ground organs. Decomposition rates of leaves were significantly higher than those of fine roots, but they were significantly and positively correlated. Finally, our results highlight that the decomposition of both leaves and roots was relatively well predicted by the leaf and root economics spectra.Our results support the existence of an acquisition-conservation trade-off axis within ferns and indicate that traits have important 'afterlife' effects on fern litter decomposition. We conclude that the plant economics spectrum theory that is commonly observed across seed plants can be applied to ferns species, thereby extending the generality of this theory to this ancient plant lineage in our study site. Our study further suggests that the evolutionary and ecological basis for the relationships among key economics traits appears to be similar between ferns and seed plants. Future studies involving larger data sets will be required to confirm these findings across different biomes at larger spatial scales.© The Author(s) 2019. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

比叶质量(LMA)是叶片经济型谱中最基础的叶功能性状, 也是重要的复合型结构参数。LMA不仅与植物的许多生理反应密切相关, 而且能定量测定光合产物在单位叶面积的投入, 因而被认为是反映植物生态策略的重要指标。目前, 有关LMA的深入研究已在植物生态学、农学、林学、植物生理学领域全面展开。该文系统阐述了LMA在叶片整体、组织、细胞三个水平的结构解析和计算方法; 重点分析了LMA对光合作用的影响; 讨论了LMA的内在遗传差异以及外部的环境胁迫因子(温度、水分、光照)对LMA的影响, 以期梳理比叶质量研究的思路、策略和方法, 为今后的研究提供借鉴和参考。

\n\nDwarf stands of the mangrove Rhizophora mangle L. are extensive in the Caribbean. We fertilized dwarf trees in Almirante Bay, Bocas del Toro Province, north‐eastern Panamá with nitrogen (N) and phosphorus (P) to determine (1) if growth limitations are due to nutrient deficiency; and (2) what morphological and/or physiological factors underlie nutrient limitations to growth.

<p id="p00005"><strong>Aims:</strong> Plant functional traits, which reflect the adaptation mechanisms of plants to their environment, are important for ecosystem function. Leaves are the main photosynthetic organs of plants and the primary research object of functional traits. However, there are few studies about the variation of leaf functional traits with the increase of canopy vertical height. Taking a lower subtropical evergreen broad-leaved forest of Dinghushan as example, our study aims to detect the changes of leaf functional traits with the canopy vertical height, and explore the influence of canopy vertical height on leaf functional traits.</p><p id="p00010"><strong>Methods:</strong> Six dominant species from a subtropical evergreen broad-leaved forest in the Dinghushan National Nature Reserve and a total of 10 leaf functional traits of these species at different canopy heights were compared and analyzed in this study. Leaf functional traits include specific leaf area (SLA), chlorophyll relative content (SPAD), leaf dry matter content (LDMC), leaf carbon content (LCC), leaf nitrogen content (LNC), leaf phosphorus content (LPC), leaf N : P (N : P), equivalent water thickness (EWT), nitrogen balance index (NBI), and flavonoids content (FLAV).</p> <p id="p00015"><strong>Results:</strong> The results revealed that: (1) With the increase of canopy vertical height, LDMC, FLAV, EWT, and LPC exhibited an increasing trend, while SLA and NBI exhibited a decreasing trend. There was a significant correlation between leaf traits and vertical height, as exemplified by FLAV and NBI, SLA and EWT with a negative correlation, while LNC and LPC were positively correlated. (2) Leaf traits showed significant discrepancy among different tree species, which might be affected by the plant&#x02019;s own characteristics and the succession process of species in the community. (3) The intraspecific variation of leaf traits demonstrated different trends along vertical layers. With the increase of canopy vertical height, 67% of species displayed a significant increase in FLAV, while the NBI of 67% of species decreased significantly.</p> <p id="p00020"><strong>Conclusion:</strong> The variation of leaf traits with the increase of canopy vertical height in the subtropical evergreen broad-leaved forest reflects the adaptation of plants to the light environment and the utilization of water resources and energy.</p>

植物功能性状能够反映植物对环境变化的响应, 从而影响生态系统功能。叶片是植物功能性状的重要研究对象, 但随着树冠垂直高度的增加, 植物叶片功能性状的变化规律仍不清楚。为了更好地解释植物对所处环境的响应机制, 本研究以鼎湖山南亚热带常绿阔叶林6个优势树种为研究对象, 对这些树种不同冠层高度的叶片比叶面积(SLA)、叶绿素相对含量(SPAD)、叶干物质含量(LDMC)、叶片碳含量(LCC)、叶片氮含量(LNC)、叶片磷含量(LPC)、叶片氮磷比(N : P)、等效水厚度(EWT)、氮平衡指数(NBI)、类黄酮含量(FLAV)共10个功能性状指标进行比较分析。结果表明: (1)随树冠垂直高度的增加, 叶干物质含量、类黄酮含量、等效水厚度和叶片磷含量呈增加趋势, 比叶面积和氮平衡指数呈减小趋势; 在冠层垂直方向上, 类黄酮含量与氮平衡指数、比叶面积与等效水厚度呈极显著负相关, 叶片氮含量与叶片磷含量呈极显著正相关。(2)不同树种叶片功能性状差异显著, 可能受植物自身特性和群落树种演替进程的影响。(3)叶片功能性状的种内差异沿垂直层次呈现不同的变化趋势。其中, 67%的树种的类黄酮含量随树冠垂直高度增加而显著增加, 67%的树种的氮平衡指数随树冠垂直高度增加而显著减小。南亚热带常绿阔叶林不同树种叶片功能性状随树冠垂直高度增加产生的变化, 反映了植物对光环境的适应以及对水资源和能量利用的不同策略。

Size-dependent changes in plant traits are an important source of intraspecific trait variation. However, there are few studies that have tested if leaf trait co-variation and/or trade-offs follow a within-genotype leaf economics spectrum (LES) related to plant size and reproductive onset. To our knowledge, there are no studies on any plant species that have tested whether or not the shape of a within-genotype LES that describes how traits covary across whole plant sizes, is the same as the shape of a within-genotype LES that represents environmentally driven trait plasticity.We quantified size-dependent variation in eight leaf traits in a single coffee genotype (Coffea arabica var. Caturra) in managed agroecosystems with different environmental conditions (light and fertilization treatments), and evaluated these patterns with respect to reproductive onset. We also evaluated if trait covariation along a within-genotype plant-size LES differed from a within-genotype environmental LES defined with trait data from coffee growing in different environmental conditions.Leaf economics traits related to resource acquisition - maximum photosynthetic rates (A) and mass-based leaf nitrogen (N) concentrations - declined linearly with plant size. Structural traits - leaf mass, leaf thickness, and leaf mass per unit area (LMA) - and leaf area increased with plant size beyond reproductive onset, then declined in larger plants. Three primary LES traits (mass-based A, leaf N and LMA) covaried across a within-genotype plant-size LES, with plants moving towards the 'resource-conserving' end of the LES as they grow larger; in coffee these patterns were nearly identical to a within-genotype environmental LES.Our results demonstrate that a plant-size LES exists within a single genotype. Our findings indicate that in managed agroecosystems where resource availability is high the role of reproductive onset in driving within-genotype trait variability, and the strength of covariation and trade-offs among LES traits, are less pronounced compared with plants in natural systems. The consistency in trait covariation in coffee along both plant-size and environmental LES axes indicates strong constraints on leaf form and function that exist within plant genotypes.© The Author(s) 2021. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

植物性状反映了植物对生长环境的响应和适应，将环境、植物个体和生态系统结构、 过程与功能联系起来（所谓的&ldquo;植物功能性状&rdquo;）。该文介绍了植物功能性状的分类体系，综述了国内外植物功能性状与气候（包括气温、降水、光照）、地理空间变异（包括地形地 貌、生态梯度、海拔）、营养、干扰（包括火灾、放牧、生物入侵、土地利用）等环境因素，以及与生态系统功能之间关系的研究进展，探讨了全球变化（气候变化和CO₂浓度升高 ） 对个体和群落植物功能性状的影响。植物功能性状的研究已经取得很多成果，并应用于全球变化、古植被恢复和古气候定量重建、环境监测与评价、生态保护和恢复等研究中，但大尺度、多生境因子下的植物功能性状研究仍有待于加强，同时需要改进性状的测量手段；我国 的植物功能性状研究还需要更加明朗化和系统化。

Coexistence of multiple species is a fundamental aspect of plant and forest ecology. Although spatial arrangement of leaves within crowns is an important determinant of light interception and productivity, shoot structure varies considerably among coexisting canopy species. We investigated the relative importance of structural traits in determining the light availability of leaves (I) and light interception efficiency at the current-year shoot level (LIE; the total light interception of leaves divided by shoot biomass) at the top of crowns of 11 canopy species in a cool-temperate forest in Japan. In accordance with Corner's rules, the total mass, stem mass, total mass of leaf laminae, individual leaf area, and stem cross-sectional area of current-year shoot were positively correlated with each other, and branching intensity (the number of current-year shoots per branch unit of 1-m length) was inversely correlated with these traits across species. In contrast, I was correlated not with these traits, but with leaf elevation angle (a ). Moreover, variation in LIE across species was caused by variation in I (thus in a ). Thus, a is a key parameter for the leaf light interception of canopy shoots in this cool-temperate forest. Differences in a across species might be related to different physiological strategies that developed in the high light and water-limited environment of forest canopies. Small variation in the length of current-year shoots among species implies that variations in I and LIE would be important for the coexistence of these canopy species.

We studied the growth and photosynthetic characteristics of a toxic (CS506) and a nontoxic strain (CS509) of the bloom-forming cyanobacterium Cylindrospermopsis raciborskii grown under identical experimental conditions. When exposed to light-saturating growth conditions (100 μmol photons · m(-2)  · s(-1) ), values for maximal photosynthetic capacity (Pmax ) and maximum quantum yield (Fv /Fm ) indicated that both strains had an equal ability to process captured photons and deliver them to PSII reaction centers. However, CS506 grew faster than CS509. This was consistent with its higher light requirement for saturation of photosynthesis (Ik ). Greater shade tolerance of CS509 was indicated by its higher ability to harvest light (α), lower photosynthetic light compensation point (Ic ), and higher chlorophyll a to biovolume ratio. Strain-specific differences were found in relation to non-photochemical quenching, effective absorption cross-sectional area of PSIIα-centers (σPSIIα), and the antenna connectivity parameter of PSIIα (Jcon PSIIα). These findings highlighted differences in the transfer of excitation from phycobilisome/PSII to PSI, on the dependence on different pigments for light harvesting and on the functioning of the PSII reaction centers between the two strains. The results of this study showed that both performance and composition of the photosynthetic apparatus are different between these strains, though with only two strains examined we cannot attribute the performance of strain 506 to its ability to produce cylindrospermopsins. The emphasis on a strain-specific light adaptation/acclimation is crucial to our understanding of how different light conditions (both quantity and quality) can trigger the occurrence of different C. raciborskii strains and control their competition and/or dominance in natural ecosystems. © 2013 Phycological Society of America.

The effect of irradiance on leaf construction costs, chemical composition, and on the payback time of leaves was investigated. To enable more generalized conclusions, three different systems were studied: top and the most-shaded leaves of 10 adult tree species in a European mixed forest, top leaves of sub-dominant trees of two evergreen species growing in small gaps or below the canopy in an Amazonian rainforest, and plants of six herbaceous and four woody species grown hydroponically at low or high irradiance in growth cabinets. Daily photon irradiance varied 3-6-fold between low- and high-light leaves. Specific leaf area (SLA) was 30-130% higher at low light. Construction costs, on the other hand, were 1-5% lower for low-irradiance leaves, mainly because low-irradiance leaves had lower concentrations of soluble phenolics. Photosynthetic capacity and respiration, expressed per unit leaf mass, were hardly different for the low- and high-light leaves. Estimates of payback times of the high-irradiance leaves ranged from 2-4 d in the growth cabinets, to 15-20 d for the adult tree species in the European forest. Low-irradiance leaves had payback times that were 2-3 times larger, ranging from 4 d in the growth cabinets to 20-80 d at the most shaded part of the canopy of the mixed forest. In all cases, estimated payback times were less than half the life span of the leaves, suggesting that even at time-integrated irradiances lower than 5% of the total seasonal value, investment in leaves is still fruitful from a carbon-economy point of view. A sensitivity analysis showed that increased SLA of low-irradiance leaves was the main factor constraining payback times. Acclimation in the other five factors determining payback time, namely construction costs, photosynthetic capacity per unit leaf mass, respiration per unit leaf mass, apparent quantum yield, and curvature of the photosynthetic light-response-curve, were unimportant when the observed variation in each factor was examined.

\n\nPatterns of leaf attributes were compared at regional and global scales in relation to the seasonal availability of water.

Despite striking differences in climate, soils, and evolutionary history among diverse biomes ranging from tropical and temperate forests to alpine tundra and desert, we found similar interspecific relationships among leaf structure and function and plant growth in all biomes. Our results thus demonstrate convergent evolution and global generality in plant functioning, despite the enormous diversity of plant species and biomes. For 280 plant species from two global data sets, we found that potential carbon gain (photosynthesis) and carbon loss (respiration) increase in similar proportion with decreasing leaf life-span, increasing leaf nitrogen concentration, and increasing leaf surface area-to-mass ratio. Productivity of individual plants and of leaves in vegetation canopies also changes in constant proportion to leaf life-span and surface area-to-mass ratio. These global plant functional relationships have significant implications for global scale modeling of vegetation-atmosphere CO2 exchange.

Many key aspects of early angiosperms are poorly known, including their ecophysiology and associated habitats. Evidence for fast-growing, weedy angiosperms comes from the Early Cretaceous Potomac Group, where angiosperm fossils, some of them putative herbs, are found in riparian depositional settings. However, inferences of growth rate from sedimentology and growth habit are somewhat indirect; also, the geographic extent of a weedy habit in early angiosperms is poorly constrained. Using a power law between petiole width and leaf mass, we estimated the leaf mass per area (LMA) of species from three Albian (110-105 Ma) fossil floras from North America (Winthrop Formation, Patapsco Formation of the Potomac Group, and the Aspen Shale). All LMAs for angiosperm species are low (<125 g/m(2); mean = 76 g/m(2)) but are high for gymnosperm species (>240 g/m(2); mean = 291 g/m(2)). On the basis of extant relationships between LMA and other leaf economic traits such as photosynthetic rate and leaf lifespan, we conclude that these Early Cretaceous landscapes were populated with weedy angiosperms with short-lived leaves (<12 mo). The unrivalled capacity for fast growth observed today in many angiosperms was in place by no later than the Albian and likely played an important role in their subsequent ecological success.

This study addresses patterns of nutrient dynamics on a precipitation gradient (1800–3500 mm y−1) in lowland tropical forest with heterogeneous soil parent material, high plant species diversity and large changes in species composition. Mean foliar concentrations of phosphorus, potassium, calcium and magnesium decreased with increasing precipitation, whereas foliar carbon:nitrogen increased with increasing precipitation. Mean foliar nitrogen:phosphorus varied from 16.4–23.8 suggesting that plant productivity at these sites is limited by phosphorus. Total soil nitrogen increased as a function of foliar litter lignin:nitrogen, whereas net nitrogen mineralization rates decreased with increasing lignin:N indicating that as litter quality decreases, more soil nitrogen is held in soil organic matter and the mineralization of that nitrogen is slower. Extractable phosphorus in soil was negatively correlated with foliar litter lignin:phosphorus, illustrating effects of litter quality on soil phosphorus availability. Overall, the results suggest that variation in plant community composition along this precipitation gradient is tightly coupled with soil nutrient cycling. Much of our understanding of effects of precipitation on nutrient cycling in tropical forest is based on precipitation gradients across montane forest in Hawaii, where species composition and soil parent material are constant. Our results suggest that variation in parent material or species composition may confound predictions developed in model island systems.

Across plant species, leaves vary enormously in their size and their venation architecture, of which one major function is to replace water lost to transpiration. The leaf hydraulic conductance (K(leaf)) represents the capacity of the transport system to deliver water, allowing stomata to remain open for photosynthesis. Previous studies showed that K(leaf) relates to vein density (vein length per area). Additionally, venation architecture determines the sensitivity of K(leaf) to damage; severing the midrib caused K(leaf) and gas exchange to decline, with lesser impacts in leaves with higher major vein density that provided more numerous water flow pathways around the damaged vein. Because xylem embolism during dehydration also reduces K(leaf), we hypothesized that higher major vein density would also reduce hydraulic vulnerability. Smaller leaves, which generally have higher major vein density, would thus have lower hydraulic vulnerability. Tests using simulations with a spatially explicit model confirmed that smaller leaves with higher major vein density were more tolerant of major vein embolism. Additionally, for 10 species ranging strongly in drought tolerance, hydraulic vulnerability, determined as the leaf water potential at 50% and 80% loss of K(leaf), was lower with greater major vein density and smaller leaf size (|r| = 0.85-0.90; P < 0.01). These relationships were independent of other aspects of physiological and morphological drought tolerance. These findings point to a new functional role of venation architecture and small leaf size in drought tolerance, potentially contributing to well-known biogeographic trends in leaf size.

Ferns and fern allies have low photosynthetic rates compared with seed plants. Their photosynthesis is thought to be limited principally by physical CO2 diffusion from the atmosphere to chloroplasts. The aim of this study was to understand the reasons for low photosynthesis in species of ferns and fern allies (Lycopodiopsida and Polypodiopsida). We performed a comprehensive assessment of the foliar gas-exchange and mesophyll structural traits involved in photosynthetic function for 35 species of ferns and fern allies. Additionally, the leaf economics spectrum (the interrelationships between photosynthetic capacity and leaf/frond traits such as leaf dry mass per unit area or nitrogen content) was tested. Low mesophyll conductance to CO2 was the main cause for low photosynthesis in ferns and fern allies, which, in turn, was associated with thick cell walls and reduced chloroplast distribution towards intercellular mesophyll air spaces. Generally, the leaf economics spectrum in ferns follows a trend similar to that in seed plants. Nevertheless, ferns and allies had less nitrogen per unit DW than seed plants (i.e. the same slope but a different intercept) and lower photosynthesis rates per leaf mass area and per unit of nitrogen. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Analysis of plant functional traits and their phylogenetic relationships has shed light on the processes structuring the occurrence patterns of angiosperm taxa across environmental gradients. In montane tropical forests, angiosperms coexist with diverse communities of terrestrial ferns, with distinct evolutionary histories, leaf morphology, and reproductive systems. Here we examined the functional traits, functional dispersion, and phylogenetic diversity of ferns across a well-described gradient of moisture and soil nutrient availability in a premontane tropical rainforest in western Panama. We measured 15 functional traits from 33 terrestrial fern species occurring in 12 one-ha plots. We applied RLQ and fourth-corner analyses to assess relationships between trait and environmental variables and used beta regression to evaluate how functional dispersion responds to environmental factors. In addition, we analyzed trait distributions with respect to fern phylogeny. We found that functional composition was predicted by soil variables and dry season rainfall. Leaf phosphorus (P) increased and leaf carbon (C) to nitrogen (N) ratio decreased with increasing soil total N:P ratio. Functional dispersion decreased with increasing soil total N:P in wet sites and with increasing manganese in dry sites, suggesting that low soil fertility and dry season moisture stress both tend to reduce functional diversity. Traits exhibited phylogenetic clustering primarily at deep nodes associated with tree versus herbaceous fern clades. Our results indicate that environmental filtering of functional traits affects ferns in a similar way to angiosperms and highlight the association of the early tree fern clade with low fertility soils.© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Mosses are an understudied group of plants that can potentially confirm or expand principles of plant function described for tracheophytes, from which they diverge strongly in structure. We quantified 35 physiological and morphological traits from cell-, leaf- and canopy-level, for 10 ground-, trunk- and branch-dwelling Hawaiian species. We hypothesized that trait values would reflect the distinctive growth form and slow growth of mosses, but also that trait correlations would be analogous to those of tracheophytes. The moss species had low leaf mass per area and low gas exchange rate. Unlike for tracheophytes, light-saturated photosynthetic rate per mass (A(mass)) did not correlate with habitat irradiance. Other photosynthetic parameters and structural traits were aligned with microhabitat irradiance, driving an inter-correlation of traits including leaf area, cell size, cell wall thickness, and canopy density. In addition, we found a coordination of traits linked with structural allocation, including costa size, canopy height and A(mass). Across species, A(mass) and nitrogen concentration correlated negatively with canopy mass per area, analogous to linkages found for the 'leaf economic spectrum', with canopy mass per area replacing leaf mass per area. Despite divergence of mosses and tracheophytes in leaf size and function, analogous trait coordination has arisen during ecological differentiation.

The three-dimensional (3-D) architecture of a peach tree (Prunus persica L. Batsch) growing in an orchard near Avignon, France, was digitized in April 1999 and again four weeks later in May 1999 to quantify increases in leaf area and crown volume as shoots developed. A 3-D model of radiation transfer was used to determine effects of changes in leaf area density and canopy volume on the spatial distribution of absorbed quantum irradiance (PAR(a)). Effects of changes in PAR(a) on leaf morphological and physiological properties were determined. Leaf mass per unit area (M(a)) and leaf nitrogen concentration per unit leaf area (N(a)) were both nonlinearly related to PAR(a), and there was a weak linear relationship between leaf nitrogen concentration per unit leaf mass (N(m)) and PAR(a). Photosynthetic capacity, defined as maximal rates of ribulose-1,5-bisphosphate carboxylase (Rubisco) carboxylation (V(cmax)) and electron transport (J(max)), was measured on leaf samples representing sunlit and shaded micro-environments at the same time that the tree crown was digitized. Both V(cmax) and J(max) were linearly related to N(a) during May, but not in April when the range of N(a) was low. Photosynthetic capacity per unit N(a) appeared to decline between April and May. Variability in leaf nitrogen partitioning between Rubisco carboxylation and electron transport was small, and the partitioning coefficients were unrelated to N(a). Spatial variability in photosynthetic capacity resulted from acclimation to varying PAR(a) as the crown developed, and acclimation was driven principally by changes in M(a) rather than the amount or partitioning of leaf nitrogen.

Gross primary production (GPP)-the uptake of carbon dioxide (CO) by leaves, and its conversion to sugars by photosynthesis-is the basis for life on land. Earth System Models (ESMs) incorporating the interactions of land ecosystems and climate are used to predict the future of the terrestrial sink for anthropogenic CO. ESMs require accurate representation of GPP. However, current ESMs disagree on how GPP responds to environmental variations, suggesting a need for a more robust theoretical framework for modelling. Here, we focus on a key quantity for GPP, the ratio of leaf internal to external CO (χ). χ is tightly regulated and depends on environmental conditions, but is represented empirically and incompletely in today's models. We show that a simple evolutionary optimality hypothesis predicts specific quantitative dependencies of χ on temperature, vapour pressure deficit and elevation; and that these same dependencies emerge from an independent analysis of empirical χ values, derived from a worldwide dataset of >3,500 leaf stable carbon isotope measurements. A single global equation embodying these relationships then unifies the empirical light-use efficiency model with the standard model of C photosynthesis, and successfully predicts GPP measured at eddy-covariance flux sites. This success is notable given the equation's simplicity and broad applicability across biomes and plant functional types. It provides a theoretical underpinning for the analysis of plant functional coordination across species and emergent properties of ecosystems, and a potential basis for the reformulation of the controls of GPP in next-generation ESMs.

Investigating the causes and consequences of intraspecific trait variation (ITV) in plants is not novel, as it has long been recognized that such variation shapes biotic and abiotic interactions. While evolutionary and population biology have extensively investigated ITV, only in the last 10 years has interest in ITV surged within community and comparative ecology.Despite this recent interest, still lacking are thorough descriptions of ITV's extent, the spatial and temporal structure of ITV, and stronger connections between ITV and community and ecosystem properties. Our primary aim in this review is to synthesize the recent literature and ask: (1) How extensive is intraspecific variation in traits across scales, and what underlying mechanisms drive this variation? (2) How does this variation impact higher-order ecological processes (e.g. population dynamics, community assembly, invasion, ecosystem productivity)? (3) What are the consequences of ignoring ITV and how can these be mitigated? and (4) What are the most pressing research questions, and how can current practices be modified to suit our research needs? Our secondary aim is to target diverse and underrepresented traits and plant organs, including anatomy, wood, roots, hydraulics, reproduction and secondary chemistry. In addressing these aims, we showcase papers from the Special Issue.Plant ITV plays a key role in determining individual and population performance, species interactions, community structure and assembly, and ecosystem properties. Its extent varies widely across species, traits and environments, and it remains difficult to develop a predictive model for ITV that is broadly applicable. Systematically characterizing the sources (e.g. ontogeny, population differences) of ITV will be a vital step forward towards identifying generalities and the underlying mechanisms that shape ITV. While the use of species means to link traits to higher-order processes may be appropriate in many cases, such approaches can obscure potentially meaningful variation. We urge the reporting of individual replicates and population means in online data repositories, a greater consideration of the mechanisms that enhance and constrain ITV's extent, and studies that span sub-disciplines.© The Author(s) 2021. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A key element of most recently proposed plant strategy schemes is an axis of resource capture, usage and availability. In the search for a simple, robust plant trait (or traits) that will allow plants to be located on this axis, specific leaf area is one of the leading contenders. Using a large new unpublished database, we examine the variability of specific leaf area and other leaf traits, the relationships between them, and their ability to predict position on the resource use axis. Specific leaf area is found to suffer from a number of drawbacks; it is both very variable between replicates and much influenced by leaf thickness. Leaf dry‐matter content (sometimes referred to as tissue density) is much less variable, largely independent of leaf thickness and a better predictor of location on an axis of resource capture, usage and availability. However, it is not clear how useful dry matter content will be outside northwest Europe, and in particular in dry climates with many succulents.

为了解黄河三角洲地下水浅埋区柽柳（Tamarix chinensis Lour.）对地下水矿化度的适应特征,运用叶片气体交换和树干液流技术,测定了地下水埋深为0.9 m时淡水、微咸水（3 g&#x000b7;L^-1）、咸水（8 g&#x000b7;L^-1）和盐水（20 g&#x000b7;L^-1）四种矿化度下柽柳的光合作用和水分利用等参数。结果表明：随地下水矿化度升高：（1）土壤水、盐含量和土壤溶液绝对浓度均逐渐升高。（2）叶片最大净光合速率和光饱和点在咸水下最高;表观量子效率、气孔导度、蒸腾速率、胞间CO₂浓度、树干液流速率等在微咸水下最高;以上指标均在盐水矿化度下最低。水分利用效率和气孔限制值在微咸水下最低,盐水下最高。在地下水埋深0.9 m时,咸水矿化度下柽柳光合效率高,光照生态幅宽,水分利用效率高,适于柽柳幼苗的生长。

以昆仑山北坡前山带驼绒藜为试验材料,测定其光合、叶片氮、磷含量及比叶面积,并检验其相关关系。研究结果表明:①光合有效辐射和土壤含水量随海拔升高而增大,温度随海拔升高而降低;②驼绒藜的光合日进程曲线为“单峰型”,且没有出现明显的“午休”现象,到上午10:00左右达到最大值,而后逐渐下降;其最大净光合速率随海拔升高而增大;③随着海拔上升,叶片氮、磷含量及比叶面积均呈升高趋势;④单位面积最大光合速率（Aarea）与叶片氮（Nmass）、磷（Pmass）含量及比叶面积（SLA）的相关性均达到极显著水平,且呈高度正相关。逐步回归分析发现对Aarea贡献大小顺序为Nmass>SLA>Pmass。