Leaf Morphological Traits Research Articles

Facilitation drives tree seedling survival at alpine treelines

Abstract Alpine treelines are considered ecological monitors recording the impacts of climate change on trees and forests. To date, most treeline research has focused on how climate change drives treeline dynamics. However, little is known about how biotic interactions mediate treeline shifts, particularly in the case of tree recruitment, a bottleneck of treeline dynamics. We hypothesized that inter- and intraspecific facilitation determined the establishment and survival of tree seedlings at alpine treelines. To test this hypothesis, 630 Abies georgei var. smithii seedlings with different ages (4–6, 7–9 and 10–15 years old) were transplanted into three growth habitats (canopy-in, canopy-out and meadow) across the alpine treeline ecotone (4300–4500 m) in the Sygera Mountains, on the southeastern Qinghai-Tibetan Plateau. Microclimate, height growth, mortality rates and leaf functional traits of transplanted seedlings were measured over 3 years. We found that the variations in leaf functional traits were driven by microclimate. After the transplantation, the leaf concentrations of soluble sugars and starch and C:P ratio increased, whereas leaf size decreased. The resource use of seedlings gradually shifted to a more conservative strategy as indicated by changes in non-structural carbohydrates and nutrient concentrations. Radiation, temperature and moisture conditions, mediated by plant interactions, influenced seedling mortality and annual growth by affecting leaf morphological traits. Our findings illustrate how facilitation plays a crucial role in altering solar radiation and leaf trait functioning, determining seedling survival and growth at alpine treelines. We provide new insights into the underlying mechanisms for tree establishment and alpine treeline shifts in response to climate change.

Consistent pattern in scaling relationships of leaf dry mass versus area of woody species co-occurring in dry-hot and wet-hot habitats

The scaling relationships between leaf dry mass (LDM) and surface area (LA) can reflect the efficiency of light harvesting and photosynthesis, as well as the ability of plants to withstand biotic and abiotic stress. However, it remains little unknown whether plants alter the scaling relationships of LDM and LA, as along with leaf mass investment per unit area in common species growing in different habitats with high temperature and contrasting water availability. This study involved measuring LA, LDM, and leaf morphological traits (e.g., leaf thickness, dry mass per unit area, and density) in 14 woody species (10 tree species, 2 shrub species, and 2 liana species) that co-occur in wet-hot (WH) and dry-hot (DH) habitats in southwest China. Our results showed that the scaling exponents (α) of LDM vs. LA were consistently greater than 1.0 (indicating the increase in LA fails to keep pace with increasing LDM) for all 14 common species at both sites, irrespective of their growth forms. Furthermore, species exhibited a higher leaf mass investment per unit area and leaf density at the DH site compared to the WH site. These results suggest that the law of “diminishing returns” applies to the scaling relationships of LDM and LA in common species inhabiting both types of habitats. Additionally, plants at the DH site increased leaf mass and density investments, potentially reflecting an essential adaptation to strong selective pressure experienced by plant species in that habitat. This study provides new insights into the scaling relationships of LDM and LA in contrasting habitats, enriching our understanding of the plant life-history strategies and adaptations in response to climate change.

Leaf functional traits and ecological niche of Fagus grandifolia and Oreomunnea mexicana in natural forests and plantings as a proxy of climate change.

Functional traits reflect species' responses to environmental variation and the breadth of their ecological niches. Fagus grandifolia and Oreomunnea mexicana have restricted distribution in upper montane cloud forests (1700-2000 m a.s.l.) in Mexico. These species were introduced into plantings at lower elevations (1200-1600 m a.s.l.) that have climates predicted for montane forests in 2050 and 2070. The aim was to relate morphological leaf traits to the ecological niche structure of each species. Leaf functional traits (leaf area, specific leaf area [SLA], thickness, and toughness) were analyzed in forests and plantings. Atmospheric circulation models and representative concentration pathways (RCPs: 2.6, 4.5, 8.5) were used to assess future climate conditions. Trait-niche relationships were analyzed by measuring the Mahalanobis distance (MD) from the forests and the plantings to the ecological niche centroid (ENC). For both species, leaf area and SLA were higher and toughness lower in plantings at lower elevation relative to those in higher-elevation forests, and thickness was similar. Leaf traits varied with distance from sites to the ENC. Forests and plantings have different environmental locations regarding the ENC, but forests are closer (MD 0.34-0.58) than plantings (MD 0.50-0.70) for both species. Elevation as a proxy for expected future climate conditions influenced the functional traits of both species, and trait patterns related to the structure of their ecological niches were consistent. The use of distances to the ENC is a promising approach to explore variability in species' functional traits and phenotypic responses in optimal versus marginal environmental conditions.

Does local soil factor drive functional leaf trait variation? A test on Neilingding Island, South China.

Leaf traits were affected by soil factors and displayed varietal differences in forest. However, few examples have been reported on the Island ecosystems. We comprehensively investigated 9 leaf traits (leaf length, leaf width, leaf area, SLA, leaf fresh weight, leaf C content, leaf N content, leaf K content, leaf C:N ratio) of 54 main subtropical woody species and soil parameters (soil pH, total C content, total N content, total K content, available N content, available P content, available K content and soil moisture) in Neilingding Island, Shenzhen, southern China. Intra-and interspecific variation of leaf traits were measured and their correlations with soil parameters were explored. The interspecific variations of leaf C:N ratio, leaf N content and leaf fresh weight were higher than their intraspecific variations. The intraspecific variation of leaf K content was larger than that of interspecific one, accounting for 80.69% of the total variance. Positive correlations were found among intraspecific coefficients of variations in leaf morphological traits. The correlation analysis between the variation of intraspecific traits and the variation of soil parameters showed that changes in soil factors affected leaf morphology and stoichiometry. The interaction between soil moisture and soil available P content was the key factor on intraspecific variations of leaf traits including leaf area, leaf fresh weight, leaf C and leaf K content. We concluded that leaf traits of plants in the island were tightly related to soil parameters. Soil parameters, especially soil moisture and available P content, affected plant leaf morphology and stoichiometry at the local scale.

Atmospheric particulate matter deposition in herbaceous species on a university campus in Colombia

Atmospheric particulate matter (PM) is one of the most harmful atmospheric pollutants with implications for human health. Plants have been used as an alternative for the removal of atmospheric PM in urban environments. The removal of PM depends on different plant morphological traits, including trichomes and epicuticles evaluated on trees. However, leaf traits for herbaceous plants commonly used in urban gardens have not been fully explored. This study used filtering to quantify the PM deposition and to describe leaf morphological traits throughout optical devices on 20 leaves from six herbaceous species –Calathea rufibarba, Calathea zebrina, Heliconia psittacorum, Heliconia rostrata, Philodendron sp. and Dieffenbachia sp. Our results suggest that structures such as trichomes –C. rufibarba– and epicuticle –H. psittacorum– play a role in PM deposition. On the other hand, large leaf size did not influence the deposition of PM per leaf unit area. Therefore, for improving city air quality, our study suggests selecting species with epidermal traits independent of leaf area. This is the first study focusing on ornamental herbaceous species ability for PM deposition in urban environments in Medellín, Colombia.

On the pre-adaptation of Mitragyna species to urban environments of Thailand

ABSTRACT As trees growing in urban environments are subjected to various stresses, it is important to select species that are naturally tolerant to such stresses. We compared the adaptability of three native Mitragyna species (M. diversifolia, M. hirsuta, and M. rotundifolia) from various parts of Thailand, growing in a wide range of environments and stresses. Various leaf morphological and physiological traits of trees growing along the roadside with their counterparts in the natural habitat were compared. The adaptability potential of the species, quantified through the plasticity index (PI), indicated an overall low plasticity for all traits. We attribute the low observed plasticity to the three species having a wide distribution range spanning diverse abiotic conditions. This includes low resource environments, and as such, they are pre-adapted to conditions similar to their native habitat. As the Mitragyna species already grow in diverse abiotic conditions, their ecological performance under stressful conditions (roadside) is not vastly different, potentially making them viable for planting in urban environments. We conclude that such species with similar trait level of PIs in both native and urban environments can successfully establish and thrive in urban green spaces under highly stressful urban conditions and provide sustained valuable ecosystem services.

Leaf Traits Explain the Growth Variation and Nitrogen Response of Eucalyptus urophylla × Eucalyptus grandis and Dalbergia odorifera in Mixed Culture.

Mixed cultivation with legumes may alleviate the nitrogen (N) limitation of monoculture Eucalyptus. However, how leaf functional traits respond to N in mixed cultivation with legumes and how they affect tree growth are unclear. Thus, this study investigated the response of leaf functional traits of Eucalyptus urophylla × Eucalyptus grandis (E. urophylla × E. grandis) and Dalbergia odorifera (D. odorifera) to mixed culture and N application, as well as the regulatory pathways of key traits on seedling growth. In this study, a pot-controlled experiment was set up, and seedling growth indicators, leaf physiology, morphological parameters, and N content were collected and analyzed after 180 days of N application treatment. The results indicated that mixed culture improved the N absorption and photosynthetic rate of E. urophylla × E. grandis, further promoting seedling growth but inhibiting the photosynthetic process of D. odorifera, reducing its growth and biomass. Redundancy analysis and path analysis revealed that leaf nitrogen content, pigment content, and photosynthesis-related physiological indicators were the traits most directly related to seedling growth and biomass accumulation, with the net photosynthetic rate explaining 50.9% and 55.8% of the variation in growth indicators for E. urophylla × E. grandis and D. odorifera, respectively. Additionally, leaf morphological traits are related to the trade-off strategy exhibited by E. urophylla × E. grandis and D. odorifera based on N competition. This study demonstrated that physiological traits related to photosynthesis are reliable predictors of N nutrition and tree growth in mixed stands, while leaf morphological traits reflect the resource trade-off strategies of different tree species.

Stomatal density, type and their relationships with leaf morphological traits in Vitis vinifera L. varieties

This study was carried out to determine the relationships between stomatal density and type and some leaf morphological traits in 10 grapevine varieties (Vitis vinifera L.). The study was performed during the vegetation period of 2022-2023 in the vineyards of the Research Station for Viticulture of Ankara University Faculty of Agriculture in Kalecik-Ankara. ‘Lival’, ‘Tekirdağ Seedless’, ‘Beauty Seedless’, ‘Michele Palieri’, ‘Cabernet Sauvignon’, ‘Narince’, ‘Syrah’, ‘Kalecik Karası’, ‘Alphonse Lavallée’ and ‘Hasandede’ varieties, grafted on 5BB rootstock, were evaluated as experimental materials in the study. The results revealed that there have been significant variations among varieties in terms of stomatal density, distribution of stomatal types, the proportion of trichomes, and leaf thickness. In general, stomatal density ranged from 168.17 to 268.27 stomata mm-2 in the varieties. The presence of the three different stomatal types (same level, raised above, and sunken) was detected by SEM images. The percentage of stomatal types varied between 39-59 for the same level, 25-42 for the raised above and 10-26 for the sunken. The percentage of the same level stomatal type was found to be higher than the other two types in all varieties. In addition, the same level stomatal type exhibited negative correlations with the raised above and the sunken stomatal types. In terms of leaf characteristics, the proportion of trichomes showed a negatively significant correlation (r = -0.309; p<0.01) with stomatal density. However, the relationship between leaf thickness and stomatal density was not significant.

Identifying quantitative trait locus and candidate genes for maize (Zea mays L.) plant architecture traits based on segregating populations constructed by high‐generation sister lines

AbstractLeaf length, width and angle are important traits in the architecture of maize plants. Delving into the genetic mechanisms of these traits is of utmost significance for promoting population yield. In this study, we employed the high‐generation sister lines PCU and PCM, which have significant differences in leaf morphological traits, as parental entities for the creation of F2 and F2:3 populations. Through quantitative trait locus (QTL) mapping of the traits in the three ear leaves by ICIM, 55 QTL were obtained, with six stable QTL selected across divergent populations. These QTL had physical spans ranging from 0.34 to 44.8 Mbp. Through gene annotation and qRT‐PCR, Zm00001d007382, Zm00001d035965, Zm00001d042777 and Zm00001d020641 were predicted as potential candidates for regulating maize plant architecture. The results of this study lay a foundation for analysing the genetic mechanisms of maize plant architecture traits and cloning‐related genes.

Effect of provenance on leaf morphological traits and secondary metabolite levels in leaf extracts of Myrtle (Myrtus communis L.) in Morocco

Myrtus communis L. is widely used as an aromatic and medicinal plant. In this work, we investigate the influence of provenance on leaf morphological traits and secondary metabolite levels in leaf extracts of Myrtle. Samples of myrtle from different geographically distinct areas were measured and analysed for polyphenols, flavonoids, condensed tannins, and antioxidant activity using the DPPH test. The analysis of result reveals the significant variance among populations in terms of morphological traits and levels of secondary compounds, particularly in terms of polyphenols, flavonoids, condensed tannins, and reducing power. Correlations between certain studied traits and environmental conditions were recorded. Leaf size and methanolic leaf extract yields from Moroccan myrtle showed as good criteria for natural population selection. Precipitation, temperature, and altitude were determinants of variation in leaf morphological traits, extract yield, and their polyphenolic, tannin, and flavonoid compounds. Based on the studied traits, three major groups were identified with few clear geographical affiliations. The IZA population from the Western Rif and GHA from the Pre-Rif formed a separate group from the other populations, characterized by the highest extract yields. The BRA population from the central plateau formed a distinct isolated group from the others. This population, collected from a location with low annual rainfall values was the richest in tannins with relatively high levels of polyphenols and flavonoids compared to other populations. This means that drought affects the amount of polyphenols and flavonoids. The geographical structure of the third group is mixed, including the IKA and AGH (Pre-Rif) populations, BS and RAB from the Central Plateau, and BT from the Western Rif.

Leaf morphological traits show greater responses to changes in climate than leaf physiological traits and gas exchange variables.

Adaptation to changing conditions is one of the strategies plants may use to survive in the face of climate change. We aimed to determine whether plants' leaf morphological and physiological traits/gas exchange variables have changed in response to recent, anthropogenic climate change. We grew seedlings from resurrected historic seeds from ex-situ seed banks and paired modern seeds in a common-garden experiment. Species pairs were collected from regions that had undergone differing levels of climate change using an emerging framework-Climate Contrast Resurrection Ecology, allowing us to hypothesise that regions with greater changes in climate (including temperature, precipitation, climate variability and climatic extremes) would be greater trait responses in leaf morphology and physiology over time. Our study found that in regions where there were greater changes in climate, there were greater changes in average leaf area, leaf margin complexity, leaf thickness and leaf intrinsic water use efficiency. Changes in leaf roundness, photosynthetic rate, stomatal density and the leaf economic strategy of our species were not correlated with changes in climate. Our results show that leaves do have the ability to respond to changes in climate, however, there are greater inherited responses in morphological leaf traits than in physiological traits/variables and greater responses to extreme measures of climate than gradual changes in climatic means. It is vital for accurate predictions of species' responses to impending climate change to ensure that future climate change ecology studies utilise knowledge about the difference in both leaf trait and gas exchange responses and the climate variables that they respond to.

Genetic variation in growth and leaf traits associated with local adaptation to climate in yellow birch (Betula alleghaniensis Britton)

Understanding patterns of variation in functional traits of hardwood trees is crucial for conserving and managing North American temperate forests under climate change. This study examined provenance variation of yellow birch ( Betula alleghaniensis Britton) in growth, biomass allocation, leaf morphology, and stable carbon isotope composition. Trees were grown from 10 seed sources originating from across Canada and the northern USA. Height and diameter were not significantly related to climate at seed origin, suggesting that variation may be better explained by site factors, such as soil pH and soil moisture. In contrast, carbon isotope composition and leaf morphological traits were significantly correlated to climate variables including temperature, precipitation, and solar radiation. Provenances from warmer, drier localities tended to have higher stable carbon isotope ratio (δ13C), greater specific leaf area, and narrower leaf width than their counterparts from cooler, wetter climates. Thus, variation in leaf morphological traits appears to be involved in adaptation of yellow birch to variation in temperature and moisture availability across the species’ range. Our results suggest that there may exist potential for selection and breeding of drought-resistant yellow birch genotypes to aid in reforestation under climate change.

Doubled Haploid Lines Derived from a European Maize Flint Landrace Contrast in Recovery from Cold Stress

Suboptimal temperatures at sowing and emergence affect the early development of maize, with potentially irreversible effects later in the growing season. We studied recovery from cold stress of an inbred line (B73) and 13 Doubled Haploid lines derived from a European flint maize landrace. After a cold treatment (20–12 °C, day–night) from sowing to seedling establishment, seedlings were transplanted and grown in the greenhouse until the V8 stage (eight leaves fully developed), when we measured agronomically relevant plant traits and spectral indices of mature leaves. Survival rates of transplanted seedlings after cold treatment ranged from 10% to 100%. After a strong delay in early development due to cold, the surviving plants were able to compensate for this delay at later stages of recovery. They reached the V8 stage after only five more growing degree days than plants grown under the control treatment (25–18 °C, day–night). Plants from the most cold-tolerant genotypes (PE0401 and PE0100) accumulated more root and shoot biomass at the end of the recovery phase compared with the same genotypes exposed to the control treatment. The genotypes with the most plastic leaf morphological traits (PE0161 and PE0072) had little reduction in leaf biomass at the end of the recovery phase in comparison with less responsive genotypes such as PE0171. We conclude that genotypes that survived cold treatment with minimal cold damage of seedling leaves can be candidates for further cold recovery studies and breeding. Nevertheless, such studies must take trait acclimation for other suboptimal conditions into consideration.

Underlying plant trait strategies for understanding the carbon sequestration in Banj oak Forest of Himalaya

Plant functional attributes are subjected to environmental adjustments, which lead to modulations in forest processes under environmental changes. However, a comprehensive assessment of the relationships between plant traits and carbon stock remains subtle. The present study attempted to accomplish the gap of knowledge by examining the linkages between forest carbon with plant traits within the Banj Oak forest in the Garhwal Himalaya. Twelve individuals from three major species in the Banj Oak forest were randomly selected for trait measurements, and soil samples were collected randomly across the area for evaluation of soil nutrients and carbon. Forest biomass and soil carbon were estimated following standard protocols. A Structural Equation Model (SEM) was applied to establish the relationship between above ground carbon (AGC) and soil organic carbon (SOC) with leaf and stem traits, and soil nutrients. Stem traits were tree height and tree diameter; whereas leaf morphological traits were leaf area, specific leaf area, leaf dry matter content; leaf physiological traits were photosynthesis rate, stomatal conductance, and transpiration rate; and leaf biochemical traits were leaf carbon concentration, leaf nitrogen concentration, and leaf phosphorus concentration. Soil nutrients were available nitrogen, available phosphorus, and exchangeable potassium. Based on SEM results, AGC of the forest was positively correlated with stem traits and leaf physiological traits, while negatively correlated with leaf morphological traits. SOC was positively correlated with soil nutrients and leaf biochemical traits, whereas negatively correlated with stem traits. These findings may support for precise quantification of forest carbon and modeling of forest carbon stocks besides providing inputs to forest managers for devising effective forest management strategies.

FAMeLeS: A multispecies and fully automated method to measure morphological leaf traits

Abstract Leaf shape parameters are of key importance to explain the role of energy balance and water economy in plant species distribution, plant productivity and, more generally, in plant–environment interactions. Yet, leaf shape measurements based on image processing are still challenging due to the high diversity of leaf shapes, colours and sizes leading to the development of time‐consuming methods with a narrow field of applicability, sometimes species‐specific or often limited to a few species. We developed a fully automated method for measuring multiple leaf shape parameters (area, perimeter, length, width, circularity and solidity) based on a large image sampling of leaf diversity (including litter) belonging to 587 species and spread over 232 countries worldwide. To evaluate the accuracy of the method to detect small objects, the sampling particularly targeted Mediterranean ecosystems (32 species and 25,205 leaves), in which small leaves often represent methodological challenges. We compared our approach and found that its mean error in leaf area measurement (+0.46%) was 1.7–148 times lower than four existing methods. It was also the only one capable of detecting and measuring all leaves in the test data set, even variegated and small leaves (less than 1 mm2). Its reliability was extensively checked on the largest and most diversified data set ever used. Our method, accessible to the broader scientific community, was simple, rapid and effective on multiple image file types and on a high diversity of leaf size, shape and colour. As such, our approach allows measurement not only on fresh leaves but also on dry leaves, such as leaf litter or leaves from herbaria. This tolerance to leaf characteristics is crucial to increase large‐scale sampling efforts and paves the way for a standardized multispecies approach to measuring leaf morphological traits for ecological and agricultural studies.

Elevational variations of leaf morphological traits and its responses to simulated climate warming in Tibetan alpine meadows

Both climate and environment changes can lead to variations in leaf morphological traits within or among herbaceous species. However, evidence for leaf morphological traits of alpine herbaceous species shifts with elevations, particularly under climate warming, is scarce. A field experimental warming experiment was conducted to address these questions in alpine meadows on the Tibetan Plateau. We measured the leaf morphological traits including leaf length, leaf width, leaf perimeter, leaf area of alpine herbaceous species along a slope of the Nyenqing-Tanggula Mountain (from 4600 m to 5200 m) on the Tibetan Plateau. Our results revealed that warming greatly decreased plant cover, species richness, and plant biomass of alpine meadows, but had no significant effects on soil carbon and nutrients. Leaf area across warming and control treatments was on average larger in low-elevation alpine meadows, and smaller toward the high-elevation alpine meadows, with leaf length and length/width ratio significantly decreased with increasing elevations. Leaf area and leaf length were positively corelated with growing season air temperature and soil temperature, but had no significant relationship with growing season precipitation, soil moisture, and photosynthetically active radiation. The decreasing elevational pattern in leaf size could be mainly attributed to the decreasing in leaf length. In response to experimental warming, our results further revealed that leaf size tended to be larger in warming plots than control plots along the elevational gradient, and the warming effects on leaf size varied greatly with herbaceous species. However, warming greatly decreased community-weighted means leaf area in mid-elevations, but increased that in both lower and higher elevations, which were mainly due to warming-induced variations in species richness and plant coverage. Our findings will fill the knowledge gap and provided valuable observational evidence in exploring elevational pattern of leaf size in Tibetan alpine meadows.

Utjecaj ekspozicije krošnje na morfološka svojstva iglica devet četinjača

The aim of this research was to investigate if the crown exposure of some conifers influenced to needle properties. The leaf morphological traits of sixty-six trees of nine conifers: Atlas cedar, Austrian pine, Blue spruce, Douglas fir, European spruce, European yew, Serbian spruce, Silver fir, and White fir, from six Belgrade parks, were analyzed. Five needles were measured from each of the four main crown exposures. Length, width, area and perimeter of needles were investigated. Species, parks in which they were found, as well as crown exposures, differed mostly in needle length and needle width. Correlations between measured needle traits were determined by linear regression analysis. Strong positive correlations were found between the length, perimeter, and area of needles. The differences among the species in terms of light requirement determine species for individual planting as light-loving or partial shade species (Atlas cedar, European spruce, Serbian spruce, Blue spruce, Austrian pine and Douglas fir), or for group planting as shade-loving species (Silver fir, White fir and European yew).

Comparison of resistance to pest infestation between native and exotic mangrove species

Pest infestation is one of the critical biotic threats to mangrove ecosystem stability. Early observations of infestation-induced damage and plant resistance could reveal the initial status of insect attacks. However, the differences between the pest resistance of native and exotic mangrove species remain poorly addressed. Here, we collected leaf photosynthetic, nutritional, morphological, and optical traits from four native and two exotic mangrove species in a subtropical mangrove ecosystem under healthy and infested conditions. Interspecific differences in resistance to pest infestation were assessed based on trait and spectral susceptibility. The results showed that photosynthetic pigments and anthocyanin correlated significantly with the health status of mangrove species. Chlorophyll a, chlorophyll b, and total chlorophyll contents in native species decreased significantly after infestation compared to those in exotic species, which led to consequent decreases in red-edge range reflectivity. Our findings demonstrate that both exotic species, Sonneratia apetala, and Sonneratia caseolaris, have much higher resistance to pest infestation than native species.

Genotypic differences in water deficit effects on leaf and crown traits in mature field-grown cocoa

Cocoa trees are highly sensitive to water stress but these negative effects may differ genetically and may be mitigated by potassium (K) application. We studied these effects on six-year-old adult trees, five genotypes produced by somatic-embryogenesis, and one by cross pollination (Hybrid), grown under sub-optimal field conditions in central Côte d'Ivoire. Trees were subjected to two soil water treatments (with or without dry season irrigation) and two K fertilization levels (with and without K). We assessed interactive effects of treatments on several leaf and crown traits: sap flux density (SF), leaf water potential (LWP), stomatal conductance (Gs), leaf size (LS), specific leaf area (SLA), leaf water content (LWC), leaf area index (LAI), light interception, litterfall and a visual index of whole-plant water stress (WSI). Mixed-effects model results revealed that withholding irrigation negatively affected SF, LWP, Gs, LS, SLA, LAI and light capture and increased WSI scores. Potassium application did not significantly mitigate the negative effects of withholding irrigation. A significant effect of genotype was observed for most of the monitored leaf physiological, morphological and crown traits. Furthermore, we found significant, positive interactions between genotype and irrigation for SF, LWP, leaf area, LS, SLA, LWC, LAI and intercepted light, suggesting that the differences in observed responses to drought conditions are genotype-specific. These results provide insights into the acclimation strategies of cocoa and genetic variation therein, and can be used to select drought-tolerant genotypes.

The ontogenetic dimension of plant functional ecology

Abstract Plant functional strategies change considerably as plants develop, driven by intraindividual variability in anatomical, morphological, physiological and architectural traits. Developmental trait variation arises through the complex interplay among genetically regulated phase change (i.e. ontogeny), increases in plant age and size, and phenotypic plasticity to changing environmental conditions. Although spatial drivers of intraspecific trait variation have received extensive research attention, developmentally driven intraspecific trait variation is largely overlooked, despite widespread occurrence. Ontogenetic trait variation is genetically regulated, leads to dramatic changes in plant phenotypes and evolves in response to predictable changes in environmental conditions as plants develop. Evidence has accumulated to support a general shift from fast to slow relative growth rates and from shade to sun leaves as plants develop from the highly competitive but shady juvenile niche to the stressful adult niche in the systems studied to date. Nonetheless, there are major gaps in our knowledge due to examination of only a few environmental factors selecting for the evolution of ontogenetic trajectories, variability in how ontogeny is assigned, biogeographic sampling biases on trees in temperate biomes, dependencies on a few broadly sampled leaf morphological traits and a lack of longitudinal studies that track ontogeny within individuals. Filling these gaps will enhance our understanding of plant functional ecology and provide a framework for predicting the effects of global change threats that target specific ontogenetic stages. Read the free Plain Language Summary for this article on the Journal blog.