ORCID Profile
0000-0002-8499-5580
Current Organisations
Graduate University of Science and Technology, Vietnam Academy of Science and Technology
,
Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology
,
Muséum National d'Histoire Naturelle
,
Western Sydney University
,
University of Idaho
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Ecology | Ecosystem Function | Ecological Physiology | Global Change Biology | Plant Physiology | Ecological Impacts of Climate Change | Ecological Applications |
ANZSRC Socio-Economic Objective (SEO)
Forest and Woodlands Land Management | Ecosystem Adaptation to Climate Change | Management of Water Consumption by Plant Production | Sparseland, Permanent Grassland and Arid Zone Land and Water Management | Forest and Woodlands Water Management | Native Forests | Mountain and High Country Land and Water Management | Flora, Fauna and Biodiversity at Regional or Larger Scales | Forest and Woodlands Flora, Fauna and Biodiversity
Related Links
Publications
Leaf traits drive differences in biomass partitioning among major plant functional types
Publisher: Cold Spring Harbor Laboratory
Date: 25-08-2015
DOI: 10.1101/025361
Abstract: 1. The partitioning of biomass into leaves and stems is one of the most uncertain and influential components of global vegetation models (GVMs). Although GVMs typically assume that the major woody plant functional types (PFTs) differ in biomass partitioning, empirical studies have not been able to justify these differences. Here we test for differences between PFTs in partitioning of biomass between leaves and stems. 2. We use the recently published Biomass And Allometry Database (BAAD), a large database including observations for in idual plants. The database covers the global climate space, allowing us to test for direct climate effects in addition to PFT. 3. The leaf mass fraction (LMF, leaf / total aboveground biomass) varied strongly between PFTs (as defined by deciduous vs. evergreen and gymnosperm vs. angiosperm). We found that LMF, once corrected for plant height, was proportional to leaf mass per area across PFTs. As a result, the PFTs did not differ in the amount of leaf area supported per unit above ground biomass. We found only weak and inconsistent effects of climate on biomass partitioning. 4. Combined, these results uncover fundamental rules in how plants are constructed and allow for systematic benchmarking of biomass partitioning routines in GVMs.
The peaked response of transpiration rate to vapour pressure deficit in field conditions can be explained by the temperature optimum of photosynthesis
Publisher: Elsevier BV
Date: 06-2014
Applying the Concept of Ecohydrological Equilibrium to Predict Steady State Leaf Area Index
Publisher: American Geophysical Union (AGU)
Date: 08-2018
DOI: 10.1029/2017MS001169
Description and test of a simple process-based model of forest growth for mixed-species stands
Publisher: Elsevier BV
Date: 05-2007
Near-optimal response of instantaneous transpiration efficiency to vapour pressure deficit, temperature and [CO2 ] in cotton (Gossypium hirsutum L.)
Publisher: Elsevier BV
Date: 2013
Using models to guide field experiments: a priori predictions for the CO 2 response of a nutrient‐ and water‐limited native Eucalypt woodland
Publisher: Wiley
Date: 09-05-2016
DOI: 10.1111/GCB.13268
Abstract: The response of terrestrial ecosystems to rising atmospheric CO2 concentration (Ca ), particularly under nutrient-limited conditions, is a major uncertainty in Earth System models. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment, recently established in a nutrient- and water-limited woodland presents a unique opportunity to address this uncertainty, but can best do so if key model uncertainties have been identified in advance. We applied seven vegetation models, which have previously been comprehensively assessed against earlier forest FACE experiments, to simulate a priori possible outcomes from EucFACE. Our goals were to provide quantitative projections against which to evaluate data as they are collected, and to identify key measurements that should be made in the experiment to allow discrimination among alternative model assumptions in a postexperiment model intercomparison. Simulated responses of annual net primary productivity (NPP) to elevated Ca ranged from 0.5 to 25% across models. The simulated reduction of NPP during a low-rainfall year also varied widely, from 24 to 70%. Key processes where assumptions caused disagreement among models included nutrient limitations to growth feedbacks to nutrient uptake autotrophic respiration and the impact of low soil moisture availability on plant processes. Knowledge of the causes of variation among models is now guiding data collection in the experiment, with the expectation that the experimental data can optimally inform future model improvements.
Corrigendum: Reconciling the optimal and empirical approaches to modelling stomatal conductance
Publisher: Wiley
Date: 04-10-2012
Understorey productivity in temperate grassy woodland responds to soil water availability but not to elevated [CO2 ]
Publisher: Wiley
Date: 14-02-2018
DOI: 10.1111/GCB.14038
Abstract: Rising atmospheric [CO
New developments in the effort to model ecosystems under water stress
Publisher: Wiley
Date: 25-08-2016
DOI: 10.1111/NPH.14082
Whole-tree chambers for elevated atmospheric CO2 experimentation and tree scale flux measurements in south-eastern Australia: The Hawkesbury Forest Experiment
Publisher: Elsevier BV
Date: 15-07-2010
fitplc - an R package to fit hydraulic vulnerability curves
Publisher: Universite de Bordeaux
Date: 16-01-2017
Abstract: We describe a toolkit to fit hydraulic vulnerability curves, such as the percent loss of xylem hydraulic conductivity ('PLC curves') as a function of the water potential. The toolkit is implemented as an R package, and is thus free to use and open source. The package fits the Weibull or sigmoidal function to measurements of PLC, conductance or conductivity, at corresponding leaf or stem water potentials. From the fitted curve, estimates of Px (the water potential at which x% conductivity is lost, e.g. the P50), and slope parameter (Sx) are provided together with confidence intervals (CI) around the fitted line. The CIs are estimated with the bootstrap. We also demonstrate the advantages of using mixed-effects models in situations where multiple in iduals are measured on a species, as compared to the more traditional approach of fitting curves separately and averaging the parameters. We demonstrate the use of the new package with ex le data on seven species measured with two different techniques.
Does canopy mean nitrogen concentration explain variation in canopy light use efficiency across 14 contrasting forest sites?
Publisher: Oxford University Press (OUP)
Date: 02-2012
Abstract: The maximum light use efficiency (LUE = gross primary production (GPP)/absorbed photosynthetic photon flux density (aPPFD)) of plant canopies has been reported to vary spatially and some of this variation has previously been attributed to plant species differences. The canopy nitrogen concentration [N] can potentially explain some of this spatial variation. However, the current paradigm of the N-effect on photosynthesis is largely based on the relationship between photosynthetic capacity (A(max)) and [N], i.e., the effects of [N] on photosynthesis rates appear under high PPFD. A maximum LUE-[N] relationship, if it existed, would influence photosynthesis in the whole range of PPFD. We estimated maximum LUE for 14 eddy-covariance forest sites, examined its [N] dependency and investigated how the [N]-maximum LUE dependency could be incorporated into a GPP model. In the model, maximum LUE corresponds to LUE under optimal environmental conditions before light saturation takes place (the slope of GPP vs. PPFD under low PPFD). Maximum LUE was higher in deciduous/mixed than in coniferous sites, and correlated significantly with canopy mean [N]. Correlations between maximum LUE and canopy [N] existed regardless of daily PPFD, although we expected the correlation to disappear under low PPFD when LUE was also highest. Despite these correlations, including [N] in the model of GPP only marginally decreased the root mean squared error. Our results suggest that maximum LUE correlates linearly with canopy [N], but that a larger body of data is required before we can include this relationship into a GPP model. Gross primary production will therefore positively correlate with [N] already at low PPFD, and not only at high PPFD as is suggested by the prevailing paradigm of leaf-level A(max)-[N] relationships. This finding has consequences for modelling GPP driven by temporal changes or spatial variation in canopy [N].
Trees tolerate an extreme heatwave via sustained transpirational cooling and increased leaf thermal tolerance
Publisher: Wiley
Date: 02-02-2018
DOI: 10.1111/GCB.14037
Abstract: Heatwaves are likely to increase in frequency and intensity with climate change, which may impair tree function and forest C uptake. However, we have little information regarding the impact of extreme heatwaves on the physiological performance of large trees in the field. Here, we grew Eucalyptus parramattensis trees for 1 year with experimental warming (+3°C) in a field setting, until they were greater than 6 m tall. We withheld irrigation for 1 month to dry the surface soils and then implemented an extreme heatwave treatment of 4 consecutive days with air temperatures exceeding 43°C, while monitoring whole-canopy exchange of CO
Reconciling the optimal and empirical approaches to modelling stomatal conductance
Publisher: Wiley
Date: 11-01-2011
Carbon dynamics of eucalypt seedlings exposed to progressive drought in elevated [CO2] and elevated temperature
Publisher: Oxford University Press (OUP)
Date: 08-2013
Abstract: Elevated [CO2] and temperature may alter the drought responses of tree seedling growth, photosynthesis, respiration and total non-structural carbohydrate (TNC) status depending on drought intensity and duration. Few studies have addressed these important climatic interactions or their consequences. We grew Eucalyptus globulus Labill. seedlings in two [CO2] concentrations (400 and 640 μl l(-1)) and two temperatures (28/17 and 32/21 °C) (day/night) in a sun-lit glasshouse, and grew them in well-watered conditions or exposed them to two drought treatments having undergone different previous water conditions (i.e., rewatered drought and sustained drought). Progressive drought in both drought treatments led to similar limitations in growth, photosynthesis and respiration, but reductions in TNC concentration were not observed. Elevated [CO2] ameliorated the impact of the drought during the moderate drought phase (i.e., Day 63 to Day 79) by increasing photosynthesis and enhancing leaf and whole-plant TNC content. In contrast, elevated temperature exacerbated the impact of the drought during the moderate drought phase by reducing photosynthesis, increasing leaf respiration and decreasing whole-plant TNC content. Extreme drought (i.e., Day 79 to Day 103) eliminated [CO2] and temperature effects on plant growth, photosynthesis and respiration. The combined effects of elevated [CO2] and elevated temperature on moderate drought stressed seedlings were reduced with progressive drought, with no sustained effects on growth despite greater whole-plant TNC content.
Optimal stomatal behaviour around the world
Publisher: Springer Science and Business Media LLC
Date: 02-03-2015
DOI: 10.1038/NCLIMATE2550
Phylogeny and foraging behaviour shape modular morphological variation in bat humeri
Publisher: Wiley
Date: 29-12-2021
DOI: 10.1111/JOA.13380
Abstract: Bats show a remarkable ecological ersity that is reflected both in dietary and foraging guilds (FGs). Cranial ecomorphological adaptations linked to diet have been widely studied in bats, using a variety of anatomical, computational and mathematical approaches. However, foraging‐related ecomorphological adaptations and the concordance between cranial and postcranial morphological adaptations remain unexamined in bats and limited to the interpretation of traditional aerodynamic properties of the wing (e.g. wing loading [WL] and aspect ratio [AR]). For this reason, the postcranial ecomorphological ersity in bats and its drivers remain understudied. Using 3D virtual modelling and geometric morphometrics (GMM), we explored the phylogenetic, ecological and biological drivers of humeral morphology in bats, evaluating the presence and magnitude of modularity and integration. To explore decoupled patterns of variation across the bone, we analysed whole‐bone shape, diaphyseal and epiphyseal shape. We also tested whether traditional aerodynamic wing traits correlate with humeral shape. By studying 37 species from 20 families (covering all FGs and 85% of dietary guilds), we found similar patterns of variation in whole‐bone and diaphyseal shape and unique variation patterns in epiphyseal shape. Phylogeny, diet and FG significantly correlated with shape variation at all levels, whereas size only had a significant effect on epiphyseal morphology. We found a significant phylogenetic signal in all levels of humeral shape. Epiphyseal shape significantly correlated with wing AR. Statistical support for a diaphyseal‐epiphyseal modular partition of the humerus suggests a functional partition of shape variability. Our study is the first to show within‐structure modular morphological variation in the appendicular skeleton of any living tetrapod. Our results suggest that diaphyseal shape correlates more with phylogeny, whereas epiphyseal shape correlates with diet and FG.
Interactive effects of elevated CO 2 and drought on nocturnal water fluxes in Eucalyptus saligna
Publisher: Oxford University Press (OUP)
Date: 25-05-2011
Abstract: Nocturnal water flux has been observed in trees under a variety of environmental conditions and can be a significant contributor to diel canopy water flux. Elevated atmospheric CO(2) (elevated [CO(2)]) can have an important effect on day-time plant water fluxes, but it is not known whether it also affects nocturnal water fluxes. We examined the effects of elevated [CO(2)] on nocturnal water flux of field-grown Eucalyptus saligna trees using sap flux through the tree stem expressed on a sapwood area (J(s)) and leaf area (E(t)) basis. After 19 months growth under well-watered conditions, drought was imposed by withholding water for 5 months in the summer, ending with a rain event that restored soil moisture. Reductions in J(s) and E(t) were observed during the severe drought period in the dry treatment under elevated [CO(2)], but not during moderate- and post-drought periods. Elevated [CO(2)] affected night-time sap flux density which included the stem recharge period, called 'total night flux' (19:00 to 05:00, J(s,r)), but not during the post-recharge period, which primarily consisted of canopy transpiration (23:00 to 05:00, J(s,c)). Elevated [CO(2)] wet (EW) trees exhibited higher J(s,r) than ambient [CO(2)] wet trees (AW) indicating greater water flux in elevated [CO(2)] under well-watered conditions. However, under drought conditions, elevated [CO(2)] dry (ED) trees exhibited significantly lower J(s,r) than ambient [CO(2)] dry trees (AD), indicating less water flux during stem recharge under elevated [CO(2)]. J(s,c) did not differ between ambient and elevated [CO(2)]. Vapour pressure deficit (D) was clearly the major influence on night-time sap flux. D was positively correlated with J(s,r) and had its greatest impact on J(s,r) at high D in ambient [CO(2)]. Our results suggest that elevated [CO(2)] may reduce night-time water flux in E. saligna when soil water content is low and D is high. While elevated [CO(2)] affected J(s,r), it did not affect day-time water flux in wet soil, suggesting that the responses of J(s,r) to environmental factors cannot be directly inferred from day-time patterns. Changes in J(s,r) are likely to influence pre-dawn leaf water potential, and plant responses to water stress. Nocturnal fluxes are clearly important for predicting effects of climate change on forest physiology and hydrology.
Vertical canopy gradients in δ13C correspond with leaf nitrogen content in a mixed-species conifer forest
Publisher: Springer Science and Business Media LLC
Date: 28-03-2006
smatr 3– an R package for estimation and inference about allometric lines
Publisher: Wiley
Date: 29-09-2011
Leaf mass per area, not total leaf area, drives differences in above‐ground biomass distribution among woody plant functional types
Publisher: Wiley
Date: 31-05-2016
DOI: 10.1111/NPH.14033
Abstract: Here, we aim to understand differences in biomass distribution between major woody plant functional types ( PFT s) (deciduous vs evergreen and gymnosperm vs angiosperm) in terms of underlying traits, in particular the leaf mass per area (LMA) and leaf area per unit stem basal area. We used a large compilation of plant biomass and size observations, including observations of 21 084 in iduals on 656 species. We used a combination of semiparametric methods and variance partitioning to test the influence of PFT , plant height, LMA, total leaf area, stem basal area and climate on above‐ground biomass distribution. The ratio of leaf mass to above‐ground woody mass ( M F / M S ) varied strongly among PFT s. We found that M F / M S at a given plant height was proportional to LMA across PFT s. As a result, the PFT s did not differ in the amount of leaf area supported per unit above‐ground biomass or per unit stem basal area. Climate consistently explained very little additional variation in biomass distribution at a given plant size. Combined, these results demonstrate consistent patterns in above‐ground biomass distribution and leaf area relationships among major woody PFTs, which can be used to further constrain global vegetation models.
Estimating annual GPP, NPP and stem growth in Finland using summary models
Publisher: Elsevier BV
Date: 2010
Plasticity influencing the light compensation point offsets the specialization for light niches across shrub species in a tropical forest understorey
Publisher: Wiley
Date: 03-06-2013
Self‐shading affects allometric scaling in trees
Publisher: Wiley
Date: 13-07-2010
Forest productivity under climate change: A checklist for evaluating model studies
Publisher: Wiley
Date: 07-03-2011
DOI: 10.1002/WCC.108
Abstract: Climate change is highly likely to impact on forest productivity over the next century. The direction and magnitude of change are uncertain because many factors are changing simultaneously, such as atmospheric composition, temperature, rainfall, and land use. Simulation models have been widely used to estimate how these interacting factors might combine to alter forest productivity. Such studies have used many different types of models with different underlying assumptions. To evaluate predictions made by such studies, it is essential to understand the type of model and the assumptions used. In this article, we provide a checklist for use when evaluating modeled estimates of climate change impacts on forest productivity. The checklist highlights the assumptions that we believe are critical in determining model outcomes. Models are classified into different general types, and assumptions relating to effects of atmospheric CO 2 concentration, temperature, water availability, nutrient cycling, and disturbance are discussed. Our main aim is to provide a guide to enable correct interpretation of model projections. The article also challenges modelers to improve the quality of information provided about their model assumptions. WIREs Clim Change 2011 2 332–355 DOI: 10.1002/wcc.108 This article is categorized under: Assessing Impacts of Climate Change Evaluating Future Impacts of Climate Change
Effects of elevated atmospheric [CO2 ] on instantaneous transpiration efficiency at leaf and canopy scales in Eucalyptus saligna
Publisher: Wiley
Date: 19-09-2012
Seasonal variation in photosynthetic capacity of montane conifers
Publisher: Wiley
Date: 12-2004
Elevated CO2 alleviates the negative impact of heat stress on wheat physiology but not on grain yield
Publisher: Oxford University Press (OUP)
Date: 24-08-2019
DOI: 10.1093/JXB/ERZ386
Abstract: Elevated CO2 protects wheat photosynthesis from heat stress damage via increased electron transport and facilitates recovery of photosynthesis and biomass but not the yield due to heat-induced grain abortion.
Canopy leaf area of a mature evergreen Eucalyptus woodland does not respond to elevated atmospheric [CO2 ] but tracks water availability
Publisher: Wiley
Date: 09-02-2016
DOI: 10.1111/GCB.13151
Abstract: Canopy leaf area, quantified by the leaf area index (L), is a crucial driver of forest productivity, water use and energy balance. Because L responds to environmental drivers, it can represent an important feedback to climate change, but its responses to rising atmospheric [CO2] and water availability of forests have been poorly quantified. We studied canopy leaf area dynamics for 28 months in a native evergreen Eucalyptus woodland exposed to free-air CO2 enrichment (the EucFACE experiment), in a subtropical climate where water limitation is common. We hypothesized that, because of expected stimulation of productivity and water-use efficiency, L should increase with elevated [CO2]. We estimated L from diffuse canopy transmittance, and measured monthly leaf litter production. Contrary to expectation, L did not respond to elevated [CO2]. We found that L varied between 1.10 and 2.20 across the study period. The dynamics of L showed a quick increase after heavy rainfall and a steady decrease during periods of low rainfall. Leaf litter production was correlated to changes in L, both during periods of decreasing L (when no leaf growth occurred) and during periods of increasing L (active shedding of old foliage when new leaf growth occurred). Leaf lifespan, estimated from mean L and total annual litter production, was up to 2 months longer under elevated [CO2] (1.18 vs. 1.01 years P = 0.05). Our main finding that L was not responsive to elevated CO2 is consistent with other forest FACE studies, but contrasts with the positive response of L commonly predicted by many ecosystem models.
MAESPA: A model to study interactions between water limitation, environmental drivers and vegetation function at tree and stand levels, with an example application to [CO2 ] × drought interactions
Publisher: Copernicus GmbH
Date: 05-07-2012
Abstract: Abstract. Process-based models (PBMs) of vegetation function can be used to interpret and integrate experimental results. Water limitation to plant carbon uptake is a highly uncertain process in the context of environmental change, and many experiments have been carried out that study drought limitations to vegetation function at spatial scales from seedlings to entire canopies. What is lacking in the synthesis of these experiments is a quantitative tool incorporating a detailed mechanistic representation of the water balance that can be used to integrate and analyse experimental results at scales of both the whole-plant and the forest canopy. To fill this gap, we developed an in idual tree-based model (MAESPA), largely based on combining the well-known MAESTRA and SPA ecosystem models. The model includes a hydraulically-based model of stomatal conductance, root water uptake routines, drainage, infiltration, runoff and canopy interception, as well as detailed radiation interception and leaf physiology routines from the MAESTRA model. The model can be applied both to single plants of arbitrary size and shape, as well as stands of trees. The utility of this model is demonstrated by studying the interaction between elevated [CO2] (eCa) and drought. Based on theory, this interaction is generally expected to be positive, so that plants growing in eCa should be less susceptible to drought. Experimental results, however, are varied. We apply the model to a previously published experiment on droughted cherry, and show that changes in plant parameters due to long-term growth at eCa (acclimation) may strongly affect the outcome of Ca × drought experiments. We discuss potential applications of MAESPA and some of the key uncertainties in process representation.
Coupled response of stomatal and mesophyll conductance to light enhances photosynthesis of shade leaves under sunflecks
Publisher: Wiley
Date: 08-11-2016
DOI: 10.1111/PCE.12841
Abstract: Light gradients within tree canopies play a major role in the distribution of plant resources that define the photosynthetic capacity of sun and shade leaves. However, the biochemical and diffusional constraints on gas exchange in sun and shade leaves in response to light remain poorly quantified, but critical for predicting canopy carbon and water exchange. To investigate the CO
Leaf area index inferred from solar beam transmission in mixed conifer forests on complex terrain
Publisher: Elsevier BV
Date: 09-2003
Does physiological acclimation to climate warming stabilize the ratio of canopy respiration to photosynthesis?
Publisher: Wiley
Date: 28-04-2016
DOI: 10.1111/NPH.13978
Abstract: Given the contrasting short‐term temperature dependences of gross primary production (GPP) and autotrophic respiration, the fraction of GPP respired by trees is predicted to increase with warming, providing a positive feedback to climate change. However, physiological acclimation may d en or eliminate this response. We measured the fluxes of aboveground respiration ( R a ), GPP and their ratio ( R a /GPP) in large, field‐grown Eucalyptus tereticornis trees exposed to ambient or warmed air temperatures (+3°C). We report continuous measurements of whole‐canopy CO 2 exchange, direct temperature response curves of leaf and canopy respiration, leaf and branch wood respiration, and diurnal photosynthetic measurements. Warming reduced photosynthesis, whereas physiological acclimation prevented a coincident increase in R a . Ambient and warmed trees had a common nonlinear relationship between the fraction of GPP that was respired above ground ( R a /GPP) and the mean daily temperature. Thus, warming significantly increased R a /GPP by moving plants to higher positions on the shared R a /GPP vs daily temperature relationship, but this effect was modest and only notable during hot conditions. Despite the physiological acclimation of autotrophic respiration to warming, increases in temperature and the frequency of heat waves may modestly increase tree R a /GPP, contributing to a positive feedback between climate warming and atmospheric CO 2 accumulation.
Bias in the mean tree model as a consequence of Jensen’s inequality
Publisher: Elsevier BV
Date: 12-2003
Boom and bust: rapid feedback responses between insect outbreak dynamics and canopy leaf area impacted by rainfall and CO 2
Publisher: Wiley
Date: 04-06-2016
DOI: 10.1111/GCB.13334
Abstract: Frequency and severity of insect outbreaks in forest ecosystems are predicted to increase with climate change. How this will impact canopy leaf area in future climates is rarely tested. Here, we document function of insect outbreaks that fortuitously and rapidly occurred in an ecosystem under free-air CO
Trajectories: how functional traits influence plant growth and shade tolerance across the life-cycle
Publisher: Cold Spring Harbor Laboratory
Date: 26-10-2016
DOI: 10.1101/083451
Abstract: Plant species differ in many functional traits that drive differences in rates of photosynthesis, biomass allocation, and tissue turnover. Yet, it remains unclear how – and even if – such traits influence whole-plant growth, with the simple linear relationships predicted by existing theory often lacking empirical support. Here we present a new theoretical framework for understanding the effect of erse functional traits on plant growth and shade-tolerance, extending a widely-used theoretical model that links growth rate in seedlings with a single leaf trait to explicitly include influences of size, light environment, and five other prominent traits: seed mass, height at maturation, leaf mass per unit leaf area, leaf nitrogen per unit leaf area, and wood density. Based on biomass production and allocation, this framework explains why the influence of prominent traits on growth rate and shade tolerance often varies with plant size and why the impact of size on growth varies among traits. Considering growth rate in height, we find the influence of: i) leaf mass per unit leaf area is strong in small plants but weakens with size, ii) leaf nitrogen per unit leaf area does not change with size, iii) wood density is present across sizes but is strongest at intermediate sizes, iv) height at maturation strengthens with size, and v) seed mass decreases with size. Moreover, we show how traits moderate plant responses to light environment and also determine shade tolerance, supporting erse empirical results. By disentangling the effects of plant size, light environment and traits on growth rates, our results provide a solid theoretical foundation for trait ecology and thus provide a platform for understanding growth across erse species around the world.
Rooting depth explains [CO 2 ]× drought interaction in Eucalyptus saligna
Publisher: Oxford University Press (OUP)
Date: 12-05-2011
Abstract: Elevated atmospheric [CO(2)] (eC(a)) often decreases stomatal conductance, which may delay the start of drought, as well as alleviate the effect of dry soil on plant water use and carbon uptake. We studied the interaction between drought and eC(a) in a whole-tree chamber experiment with Eucalyptus saligna. Trees were grown for 18 months in their C(a) treatments before a 4-month dry-down. Trees grown in eC(a) were smaller than those grown in ambient C(a) (aC(a)) due to an early growth setback that was maintained throughout the duration of the experiment. Pre-dawn leaf water potentials were not different between C(a) treatments, but were lower in the drought treatment than the irrigated control. Counter to expectations, the drought treatment caused a larger reduction in canopy-average transpiration rates for trees in the eC(a) treatment compared with aC(a). Total tree transpiration over the dry-down was positively correlated with the decrease in soil water storage, measured in the top 1.5 m, over the drying cycle however, we could not close the water budget especially for the larger trees, suggesting soil water uptake below 1.5 m depth. Using neutron probe soil water measurements, we estimated fractional water uptake to a depth of 4.5 m and found that larger trees were able to extract more water from deep soil layers. These results highlight the interaction between rooting depth and response of tree water use to drought. The responses of tree water use to eC(a) involve interactions between tree size, root distribution and soil moisture availability that may override the expected direct effects of eC(a). It is essential that these interactions be considered when interpreting experimental results.
Light inhibition of leaf respiration in field-grown Eucalyptus saligna in whole-tree chambers under elevated atmospheric CO2 and summer drought
Publisher: Wiley
Date: 14-12-2011
DOI: 10.1111/J.1365-3040.2011.02465.X
Abstract: We investigated whether the degree of light inhibition of leaf respiration (R) differs among large Eucalyptus saligna grown in whole-tree chambers and exposed to present and future atmospheric [CO(2) ] and summer drought. Associated with month-to-month changes in temperature were concomitant changes in R in the light (R(light) ) and darkness (R(dark) ), with both processes being more temperature dependent in well-watered trees than under drought. Overall rates of R(light) and R(dark) were not significantly affected by [CO(2) ]. By contrast, overall rates of R(dark) (averaged across both [CO(2) ]) were ca. 25% lower under drought than in well-watered trees. During summer, the degree of light inhibition of leaf R was greater in droughted (ca. 80% inhibition) than well-watered trees (ca. 50% inhibition). Notwithstanding these treatment differences, an overall positive relationship was observed between R(light) and R(dark) when data from all months/treatments were combined (R(2) = 0.8). Variations in R(light) were also positively correlated with rates of Rubisco activity and nitrogen concentration. Light inhibition resulted in a marked decrease in the proportion of light-saturated photosynthesis respired (i.e. reduced R/A(sat) ). Collectively, these results highlight the need to account for light inhibition when assessing impacts of global change drivers on the carbon economy of tree canopies.
How should we model plant responses to drought? An analysis of stomatal and non-stomatal responses to water stress
Publisher: Elsevier BV
Date: 12-2013
A test of an optimal stomatal conductance scheme within the CABLE land surface model
Publisher: Copernicus GmbH
Date: 24-02-2015
Abstract: Abstract. Stomatal conductance (gs) affects the fluxes of carbon, energy and water between the vegetated land surface and the atmosphere. We test an implementation of an optimal stomatal conductance model within the Community Atmosphere Biosphere Land Exchange (CABLE) land surface model (LSM). In common with many LSMs, CABLE does not differentiate between gs model parameters in relation to plant functional type (PFT), but instead only in relation to photosynthetic pathway. We constrained the key model parameter "g1", which represents plant water use strategy, by PFT, based on a global synthesis of stomatal behaviour. As proof of concept, we also demonstrate that the g1 parameter can be estimated using two long-term average (1960–1990) bioclimatic variables: (i) temperature and (ii) an indirect estimate of annual plant water availability. The new stomatal model, in conjunction with PFT parameterisations, resulted in a large reduction in annual fluxes of transpiration (~ 30% compared to the standard CABLE simulations) across evergreen needleleaf, tundra and C4 grass regions. Differences in other regions of the globe were typically small. Model performance against upscaled data products was not degraded, but did not noticeably reduce existing model–data biases. We identified assumptions relating to the coupling of the vegetation to the atmosphere and the parameterisation of the minimum stomatal conductance as areas requiring further investigation in both CABLE and potentially other LSMs. We conclude that optimisation theory can yield a simple and tractable approach to predicting stomatal conductance in LSMs.
Elevated [CO E ucalyptus radiata seedlings
Publisher: Wiley
Date: 13-02-2014
DOI: 10.1111/PCE.12260
Abstract: It has been reported that elevated temperature accelerates the time-to-mortality in plants exposed to prolonged drought, while elevated [CO(2)] acts as a mitigating factor because it can reduce stomatal conductance and thereby reduce water loss. We examined the interactive effects of elevated [CO(2)] and temperature on the inter-dependent carbon and hydraulic characteristics associated with drought-induced mortality in Eucalyptus radiata seedlings grown in two [CO(2)] (400 and 640 μL L(-1)) and two temperature (ambient and ambient +4 °C) treatments. Seedlings were exposed to two controlled drying and rewatering cycles, and then water was withheld until plants died. The extent of xylem cavitation was assessed as loss of stem hydraulic conductivity. Elevated temperature triggered more rapid mortality than ambient temperature through hydraulic failure, and was associated with larger water use, increased drought sensitivities of gas exchange traits and earlier occurrence of xylem cavitation. Elevated [CO(2)] had a negligible effect on seedling response to drought, and did not ameliorate the negative effects of elevated temperature on drought. Our findings suggest that elevated temperature and consequent higher vapour pressure deficit, but not elevated [CO(2)], may be the primary contributors to drought-induced seedling mortality under future climates.
On the minimum leaf conductance: its role in models of plant water use, and ecological and environmental controls
Publisher: Wiley
Date: 25-08-2019
DOI: 10.1111/NPH.15395
Abstract: Contents Summary 693 I. Introduction 693 II. Comparison of various definitions and measurement techniques of minimum conductance 694 III. Cuticular conductance 695 IV. Contribution of stomata 696 V. Environmental and ecological variation in minimum conductance 696 VI. Use of minimum conductance in models 698 VII. Conclusions 703 Acknowledgements 703 References 703 SUMMARY: When the rate of photosynthesis is greatly diminished, such as during severe drought, extreme temperature or low light, it seems advantageous for plants to close stomata and completely halt water loss. However, water loss continues through the cuticle and incompletely closed stomata, together constituting the leaf minimum conductance (g
Desiccation time during drought is highly predictable across species of Eucalyptus from contrasting climates
Publisher: Wiley
Date: 08-08-2019
DOI: 10.1111/NPH.16042
Abstract: Catastrophic failure of the water transport pathway in trees is a principal mechanism of mortality during extreme drought. To be able to predict the probability of mortality at an in idual and landscape scale we need knowledge of the time for plants to reach critical levels of hydraulic failure. We grew plants of eight species of Eucalyptus originating from contrasting climates before allowing a subset to dehydrate. We tested whether a trait-based model of time to plant desiccation t
Light interception efficiency explained by two simple variables: A test using a diversity of small- to medium-sized woody plants
Publisher: Wiley
Date: 08-11-2012
DOI: 10.1111/J.1469-8137.2011.03943.X
Abstract: • Plant light interception efficiency is a crucial determinant of carbon uptake by in idual plants and by vegetation. Our aim was to identify whole-plant variables that summarize complex crown architecture, which can be used to predict light interception efficiency. • We gathered the largest database of digitized plants to date (1831 plants of 124 species), and estimated a measure of light interception efficiency with a detailed three-dimensional model. Light interception efficiency was defined as the ratio of the hemispherically averaged displayed to total leaf area. A simple model was developed that uses only two variables, crown density (the ratio of leaf area to total crown surface area) and leaf dispersion (a measure of the degree of aggregation of leaves). • The model explained 85% of variation in the observed light interception efficiency across the digitized plants. Both whole-plant variables varied across species, with differences in leaf dispersion related to leaf size. Within species, light interception efficiency decreased with total leaf number. This was a result of changes in leaf dispersion, while crown density remained constant. • These results provide the basis for a more general understanding of the role of plant architecture in determining the efficiency of light harvesting.
Co-optimal distribution of leaf nitrogen and hydraulic conductance in plant canopies
Publisher: Oxford University Press (OUP)
Date: 05-04-2012
Abstract: Leaf properties vary significantly within plant canopies, due to the strong gradient in light availability through the canopy, and the need for plants to use resources efficiently. At high light, photosynthesis is maximized when leaves have a high nitrogen content and water supply, whereas at low light leaves have a lower requirement for both nitrogen and water. Studies of the distribution of leaf nitrogen (N) within canopies have shown that, if water supply is ignored, the optimal distribution is that where N is proportional to light, but that the gradient of N in real canopies is shallower than the optimal distribution. We extend this work by considering the optimal co-allocation of nitrogen and water supply within plant canopies. We developed a simple 'toy' two-leaf canopy model and optimized the distribution of N and hydraulic conductance (K) between the two leaves. We asked whether hydraulic constraints to water supply can explain shallow N gradients in canopies. We found that the optimal N distribution within plant canopies is proportional to the light distribution only if hydraulic conductance, K, is also optimally distributed. The optimal distribution of K is that where K and N are both proportional to incident light, such that optimal K is highest to the upper canopy. If the plant is constrained in its ability to construct higher K to sun-exposed leaves, the optimal N distribution does not follow the gradient in light within canopies, but instead follows a shallower gradient. We therefore hypothesize that measured deviations from the predicted optimal distribution of N could be explained by constraints on the distribution of K within canopies. Further empirical research is required on the extent to which plants can construct optimal K distributions, and whether shallow within-canopy N distributions can be explained by sub-optimal K distributions.
How do leaf and ecosystem measures of water-use efficiency compare?
Publisher: Wiley
Date: 02-06-2017
DOI: 10.1111/NPH.14626
Abstract: The terrestrial carbon and water cycles are intimately linked: the carbon cycle is driven by photosynthesis, while the water balance is dominated by transpiration, and both fluxes are controlled by plant stomatal conductance. The ratio between these fluxes, the plant water-use efficiency (WUE), is a useful indicator of vegetation function. WUE can be estimated using several techniques, including leaf gas exchange, stable isotope discrimination, and eddy covariance. Here we compare global compilations of data for each of these three techniques. We show that patterns of variation in WUE across plant functional types (PFTs) are not consistent among the three datasets. Key discrepancies include the following: leaf-scale data indicate differences between needleleaf and broadleaf forests, but ecosystem-scale data do not leaf-scale data indicate differences between C
The optimal stomatal response to atmospheric CO2 concentration: Alternative solutions, alternative interpretations
Publisher: Elsevier BV
Date: 12-2013
Related Organisations
Graduate University Of Science And Technology, Vietnam Academy Of Science And Technology
Location: Viet Nam
Institute Of Ecology And Biological Resources, Vietnam Academy Of Science And Technology
Location: Viet Nam
Related Funding Activities
Discovery Projects - Grant ID: DP120104055
Start Date: 02-2012
End Date: 09-2016
Amount: $330,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP140100232
Start Date: 02-2015
End Date: 12-2018
Amount: $331,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP160103436
Start Date: 03-2016
End Date: 06-2019
Amount: $428,100.00
Funder: Australian Research Council
View Funded Activity