ORCID Profile
0000-0002-5607-4741
Current Organisation
USDA Agricultural Research Service
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Publisher: Cold Spring Harbor Laboratory
Date: 05-02-2021
Publisher: Wiley
Date: 15-01-2023
DOI: 10.1111/PCE.14536
Abstract: The efficiency‐safety tradeoff has been thoroughly investigated in plants, especially concerning their capacity to transport water and avoid embolism. Stomatal regulation is a vital plant behaviour to respond to soil and atmospheric water limitation. Recently, a stomatal efficiency‐safety tradeoff was reported where plants with higher maximum stomatal conductance ( g max ) exhibited greater sensitivity to stomatal closure during soil drying, that is, less negative leaf water potential at 50% g max ( ψ gs50 ). However, the underlying mechanism of this g max ‐ ψ gs50 tradeoff remains unknown. Here, we utilized a soil‐plant hydraulic model, in which stomatal closure is triggered by nonlinearity in soil‐plant hydraulics, to investigate such tradeoff. Our simulations show that increasing g max is aligned with less negative ψ gs50 . Plants with higher g max (also higher transpiration) require larger quantities of water to be moved across the rhizosphere, which results in a precipitous decrease in water potential at the soil‐root interface, and therefore in the leaves. We demonstrated that the g max ‐ ψ gs50 tradeoff can be predicted based on soil‐plant hydraulics, and is impacted by plant hydraulic properties, such as plant hydraulic conductance, active root length and embolism resistance. We conclude that plants may therefore adjust their growth and/or their hydraulic properties to adapt to contrasting habitats and climate conditions.
Publisher: Frontiers Media SA
Date: 05-07-2022
Publisher: Research Square Platform LLC
Date: 06-12-2022
DOI: 10.21203/RS.3.RS-2344990/V1
Abstract: The evolution of xylem vessels and dense leaf vein networks in flowering plants enabled unprecedented increases in plant water transport and rates of CO 2 assimilation. We tested the hypothesis that independent of vein density, higher leaf vein topological efficiency ( VTE ), achieved with denser free vein endings, would reduce the extraxylary pathlength, further benefitting whole-leaf conductance, while reducing carbon investment, and releasing space for light capture. Our analysis across 52 phylogenetically erse angiosperm species demonstrated that for a given vein density, high VTE conferred by dense free endings can shorten the extraxylary pathlength by up to 11%. Across species, high VTE was associated with high stomatal conductance, non-vein area fraction for light capture, and low leaf mass per area. Our findings identify leaf vein topological efficiency as an important measure of the use of leaf space and biomass, and a key factor influencing plant adaptation to historical and future environmental conditions.
Publisher: Springer Science and Business Media LLC
Date: 30-09-2021
DOI: 10.1038/S41597-021-01006-6
Abstract: We introduce the AusTraits database - a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field c aigns, published literature, taxonomic monographs, and in idual taxon descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological attributes (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised in idual- and species-level measurements coupled to, where available, contextual information on site properties and experimental conditions. This article provides information on version 3.0.2 of AusTraits which contains data for 997,808 trait-by-taxon combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data, which also provides a template for other national or regional initiatives globally to fill persistent gaps in trait knowledge.
Publisher: Wiley
Date: 08-2023
DOI: 10.1111/PPL.14006
Publisher: Oxford University Press (OUP)
Date: 08-04-2022
Publisher: Wiley
Date: 21-06-2018
DOI: 10.1111/PCE.13345
Abstract: This article comments on: Water relations of Calycanthus flowers: Hydraulic conductance, capacitance, and embolism resistance.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-2019
Abstract: Coordination between plant height and xylem traits is aligned with habitat aridity across the Earth’s terrestrial biomes.
Publisher: Wiley
Date: 08-2022
Abstract: Leaf dry mass per unit area (LMA), carboxylation capacity ( V cmax ) and leaf nitrogen per unit area (N area ) and mass (N mass ) are key traits for plant functional ecology and ecosystem modelling. There is however no consensus about how these traits are regulated, or how they should be modelled. Here we confirm that observed leaf nitrogen across species and sites can be estimated well from observed LMA and V cmax at 25°C ( V cmax25 ). We then test the hypothesis that global variations of both quantities depend on climate variables in specific ways that are predicted by leaf‐level optimality theory, thus allowing both N area to be predicted as functions of the growth environment. A new global compilation of field measurements was used to quantify the empirical relationships of leaf N to V cmax25 and LMA. Relationships of observed V cmax25 and LMA to climate variables were estimated, and compared to independent theoretical predictions of these relationships. Soil effects were assessed by analysing biases in the theoretical predictions. LMA was the most important predictor of N area (increasing) and N mass (decreasing). About 60% of global variation across species and sites in observed N area , and 31% in N mass , could be explained by observed LMA and V cmax25 . These traits, in turn, were quantitatively related to climate variables, with significant partial relationships similar or indistinguishable from those predicted by optimality theory. Predicted trait values explained 21% of global variation in observed site‐mean V cmax25 , 43% in LMA and 31% in N area . Predicted V cmax25 was biased low on clay‐rich soils but predicted LMA was biased high, with compensating effects on N area . N area was overpredicted on organic soils. Synthesis . Global patterns of variation in observed site‐mean N area can be explained by climate‐induced variations in optimal V cmax25 and LMA. Leaf nitrogen should accordingly be modelled as a consequence (not a cause) of V cmax25 and LMA, both being optimized to the environment. Nitrogen limitation of plant growth would then be modelled principally via whole‐plant carbon allocation, rather than via leaf‐level traits. Further research is required to better understand and model the terrestrial nitrogen and carbon cycles and their coupling.
Publisher: Elsevier BV
Date: 04-2018
Publisher: Frontiers Media SA
Date: 03-02-2021
Publisher: Elsevier BV
Date: 03-2019
Publisher: Wiley
Date: 11-09-2017
Publisher: Cold Spring Harbor Laboratory
Date: 14-03-2022
DOI: 10.1101/2022.03.11.482897
Abstract: Plant function arises from a complex network of structural and physiological traits. Explicit representation of these traits, as well as their connections with other biophysical processes, is required to advance our understanding of plant-soil-climate interactions. We used the Terrestrial Regional Ecosystem Exchange Simulator (TREES) to evaluate physiological trait networks in maize. Net primary productivity (NPP) and grain yield were simulated across five contrasting climate scenarios. Simulations achieving high NPP and grain yield in high precipitation environments featured trait networks conferring high water use strategies: deep roots, high stomatal conductance at low water potential (“risky” stomatal regulation), high xylem hydraulic conductivity, and high maximal leaf area index. In contrast, high NPP and grain yield was achieved in dry environments with low late-season precipitation via water conserving trait networks: deep roots, high embolism resistance, and low stomatal conductance at low leaf water potential (“conservative” stomatal regulation). We suggest that our approach, which allows for the simultaneous evaluation of physiological traits and their interactions (i.e., networks), has potential to improve crop growth predictions in different environments. In contrast, evaluating single traits in isolation of other coordinated traits does not appear to be an effective strategy for predicting plant performance. Our process-based model uncovered two beneficial but contrasting trait networks for maize which can be understood by their integrated effect on water use/conservation. Modification of multiple, physiologically aligned, traits were required to bring about meaningful improvements in NPP and yield.
Publisher: Brill
Date: 20-10-2023
Publisher: Wiley
Date: 07-04-2021
DOI: 10.1111/PPL.13400
Publisher: Elsevier BV
Date: 02-2019
Publisher: Wiley
Date: 16-11-2022
DOI: 10.1111/GCB.16501
Abstract: “Least‐cost theory” posits that C 3 plants should balance rates of photosynthetic water loss and carboxylation in relation to the relative acquisition and maintenance costs of resources required for these activities. Here we investigated the dependency of photosynthetic traits on climate and soil properties using a new Australia‐wide trait dataset spanning 528 species from 67 sites. We tested the hypotheses that plants on relatively cold or dry sites, or on relatively more fertile sites, would typically operate at greater CO 2 drawdown (lower ratio of leaf internal to ambient CO 2 , C i : C a ) during light‐saturated photosynthesis, and at higher leaf N per area (N area ) and higher carboxylation capacity ( V cmax 25 ) for a given rate of stomatal conductance to water vapour, g sw . These results would be indicative of plants having relatively higher water costs than nutrient costs. In general, our hypotheses were supported. Soil total phosphorus (P) concentration and (more weakly) soil pH exerted positive effects on the N area – g sw and V cmax 25 – g sw slopes, and negative effects on C i : C a . The P effect strengthened when the effect of climate was removed via partial regression. We observed similar trends with increasing soil cation exchange capacity and clay content, which affect soil nutrient availability, and found that soil properties explained similar amounts of variation in the focal traits as climate did. Although climate typically explained more trait variation than soil did, together they explained up to 52% of variation in the slope relationships and soil properties explained up to 30% of the variation in in idual traits. Soils influenced photosynthetic traits as well as their coordination. In particular, the influence of soil P likely reflects the Australia's geologically ancient low‐relief landscapes with highly leached soils. Least‐cost theory provides a valuable framework for understanding trade‐offs between resource costs and use in plants, including limiting soil nutrients.
Publisher: Elsevier BV
Date: 02-2017
Publisher: Wiley
Date: 10-2020
DOI: 10.1111/PCE.13891
Publisher: Wiley
Date: 30-10-2020
DOI: 10.1111/NPH.16961
Publisher: Wiley
Date: 19-09-2022
DOI: 10.1111/NPH.18447
Abstract: Hydraulic failure resulting from drought-induced embolism in the xylem of plants is a key determinant of reduced productivity and mortality. Methods to assess this vulnerability are difficult to achieve at scale, leading to alternative metrics and correlations with more easily measured traits. These efforts have led to the longstanding and pervasive assumed mechanistic link between vessel diameter and vulnerability in angiosperms. However, there are at least two problems with this assumption that requires critical re-evaluation: (1) our current understanding of drought-induced embolism does not provide a mechanistic explanation why increased vessel width should lead to greater vulnerability, and (2) the most recent advancements in nanoscale embolism processes suggest that vessel diameter is not a direct driver. Here, we review data from physiological and comparative wood anatomy studies, highlighting the potential anatomical and physicochemical drivers of embolism formation and spread. We then put forward key knowledge gaps, emphasising what is known, unknown and speculation. A meaningful evaluation of the diameter-vulnerability link will require a better mechanistic understanding of the biophysical processes at the nanoscale level that determine embolism formation and spread, which will in turn lead to more accurate predictions of how water transport in plants is affected by drought.
Publisher: Cold Spring Harbor Laboratory
Date: 07-01-2021
DOI: 10.1101/2021.01.04.425314
Abstract: We introduce the AusTraits database - a compilation of measurements of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 375 traits across 29230 taxa from field c aigns, published literature, taxonomic monographs, and in idual taxa descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological parameters (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised in idual-, species- and genus-level observations coupled to, where available, contextual information on site properties. This data descriptor provides information on version 2.1.0 of AusTraits which contains data for 937243 trait-by-taxa combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data to increase our collective understanding of the Australian flora.
Publisher: Wiley
Date: 31-12-2019
DOI: 10.1111/GCB.14904
Abstract: Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to bio ersity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on in idual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
Publisher: Wiley
Date: 07-07-2022
DOI: 10.1111/PCE.14382
Abstract: Plant function arises from a complex network of structural and physiological traits. Explicit representation of these traits, as well as their connections with other biophysical processes, is required to advance our understanding of plant‐soil‐climate interactions. We used the Terrestrial Regional Ecosystem Exchange Simulator (TREES) to evaluate physiological trait networks in maize. Net primary productivity (NPP) and grain yield were simulated across five contrasting climate scenarios. Simulations achieving high NPP and grain yield in high precipitation environments featured trait networks conferring high water use strategies: deep roots, high stomatal conductance at low water potential (“risky” stomatal regulation), high xylem hydraulic conductivity and high maximal leaf area index. In contrast, high NPP and grain yield was achieved in dry environments with low late‐season precipitation via water conserving trait networks: deep roots, high embolism resistance and low stomatal conductance at low leaf water potential (“conservative” stomatal regulation). We suggest that our approach, which allows for the simultaneous evaluation of physiological traits, soil characteristics and their interactions (i.e., networks), has potential to improve our understanding of crop performance in different environments. In contrast, evaluating single traits in isolation of other coordinated traits does not appear to be an effective strategy for predicting plant performance.
Publisher: Cold Spring Harbor Laboratory
Date: 18-09-2019
DOI: 10.1101/772764
Abstract: Water released from wood tissue during transpiration (capacitance) can meaningfully affect daily water use and drought response. To provide context for better understanding of capacitance mechanisms, we investigated links between capacitance and wood anatomy. On twig wood of 30 temperate angiosperm tree species, we measured capacitance, water content, wood density, and anatomical traits, i.e., vessel dimensions, tissue fractions, and vessel-tissue contact fractions (fraction of vessel circumference in contact with other tissues). Across all species, the strongest predictors of capacitance were wood density (WD) and predawn lumen volumetric water content (VWC L-pd , r 2 adj =0.44, P .0001). Vessel-tissue contact fractions explained an additional ∼10% of the variation in capacitance. Regression models were not improved by including predawn relative water content (RWC pd ) or tissue lumen fractions. Among diffuse-porous species, VWC L-pd and vessel-ray contact fraction were the best predictors of capacitance, whereas among ring/semi-ring-porous species, VWC L-pd , WD and vessel-fibre contact fraction were the best predictors. Mean RWC pd was 0.65±0.13 and uncorrelated with WD. VWC L-pd was weakly negatively correlated with WD. Our findings imply that capacitance depends on the amount of stored water, tissue connectivity and the bulk wood properties arising from WD (e.g., elasticity), rather than the fraction of any particular tissue.
Publisher: Wiley
Date: 27-10-2020
DOI: 10.1111/NPH.16969
Abstract: The evolution of angiosperms was accompanied by the segregation and specialisation of their xylem tissues. This study aimed to determine whether the fraction and arrangement of parenchyma tissue influence the hydraulic efficiency–safety trade‐off in the basal angiosperms. We examined xylem anatomical structure and hydraulic functioning of 28 woody species of Magnoliids in a tropical rainforest of Madagascar and reported, for the first time, quantitative measurements that support the relationship between vessel‐to‐xylem parenchyma connectivity and the hydraulic efficiency–safety trade‐off. We also introduced a new measurement – the distance of species from the trade‐off limit – to quantify the co‐optimisation of hydraulic efficiency and safety. Although the basal angiosperms in this study had low hydraulic conductivity and safety, species with higher axial parenchyma fraction ( APf ) had significantly higher hydraulic conductivity. Hydraulic efficiency–safety optimisation was accompanied by higher APf and vessel‐to‐axial parenchyma connectivity. Conversely, species exhibiting high ray parenchyma fraction and high vessel‐to‐ray connectivity had lower K s and were further away from the hydraulic trade‐off limit line. Our results provide evidence that axial parenchyma fraction and paratracheal arrangement are associated with both enhanced hydraulic efficiency and safety.
Publisher: Wiley
Date: 15-10-2020
DOI: 10.1111/NPH.16940
Abstract: A classic theory proposes that plant xylem cannot be both highly efficient in water transport and resistant to embolism, and therefore a hydraulic efficiency–safety trade‐off should exist. However, the trade‐off is weak, and many species exhibit both low efficiency and low safety, falling outside of the expected trade‐off space. It remains unclear under what climatic conditions these species could maintain competitive fitness. We compiled hydraulic efficiency and safety traits for 682 observations of 499 woody species from 178 sites world‐wide and measured the position of each observation within the proposed trade‐off space. For both angiosperms and gymnosperms, observations from sites with high climatic seasonality, especially precipitation seasonality, tended to have higher hydraulic safety and efficiency than observations from sites with low seasonality. Specifically, high vapour pressure deficit, high solar radiation, and low precipitation during the wet season were driving factors. Strong climatic seasonality and drought in both dry and wet seasons appear to be ecological filters that select for species with co‐optimized safety and efficiency, whereas the opposite environmental conditions may allow the existence of plants with low efficiency and safety.
Location: United States of America
No related grants have been discovered for Sean Gleason.