207 results on '"Barton, Craig V M'
Search Results
2. Pastures and Climate Extremes: Impacts of Cool Season Warming and Drought on the Productivity of Key Pasture Species in a Field Experiment
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Amber C. Churchill, Haiyang Zhang, Kathryn J. Fuller, Burhan Amiji, Ian C. Anderson, Craig V. M. Barton, Yolima Carrillo, Karen L. M. Catunda, Manjunatha H. Chandregowda, Chioma Igwenagu, Vinod Jacob, Gil Won Kim, Catriona A. Macdonald, Belinda E. Medlyn, Ben D. Moore, Elise Pendall, Jonathan M. Plett, Alison K. Post, Jeff R. Powell, David T. Tissue, Mark G. Tjoelker, and Sally A. Power
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climate warming ,seasonal drought ,plant functional groups ,grassland ,rangeland ,aboveground production ,Plant culture ,SB1-1110 - Abstract
Shifts in the timing, intensity and/or frequency of climate extremes, such as severe drought and heatwaves, can generate sustained shifts in ecosystem function with important ecological and economic impacts for rangelands and managed pastures. The Pastures and Climate Extremes experiment (PACE) in Southeast Australia was designed to investigate the impacts of a severe winter/spring drought (60% rainfall reduction) and, for a subset of species, a factorial combination of drought and elevated temperature (ambient +3°C) on pasture productivity. The experiment included nine common pasture and Australian rangeland species from three plant functional groups (C3 grasses, C4 grasses and legumes) planted in monoculture. Winter/spring drought resulted in productivity declines of 45% on average and up to 74% for the most affected species (Digitaria eriantha) during the 6-month treatment period, with eight of the nine species exhibiting significant yield reductions. Despite considerable variation in species’ sensitivity to drought, C4 grasses were more strongly affected by this treatment than C3 grasses or legumes. Warming also had negative effects on cool-season productivity, associated at least partially with exceedance of optimum growth temperatures in spring and indirect effects on soil water content. The combination of winter/spring drought and year-round warming resulted in the greatest yield reductions. We identified responses that were either additive (Festuca), or less-than-additive (Medicago), where warming reduced the magnitude of drought effects. Results from this study highlight the sensitivity of diverse pasture species to increases in winter and spring drought severity similar to those predicted for this region, and that anticipated benefits of cool-season warming are unlikely to be realized. Overall, the substantial negative impacts on productivity suggest that future, warmer, drier climates will result in shortfalls in cool-season forage availability, with profound implications for the livestock industry and natural grazer communities.
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- 2022
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3. The partitioning of gross primary production for young Eucalyptus tereticornis trees under experimental warming and altered water availability
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Drake, John E., Tjoelker, Mark G., Aspinwall, Michael J., Reich, Peter B., Pfautsch, Sebastian, and Barton, Craig V. M.
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- 2019
4. Climate warming and tree carbon use efficiency in a whole-tree 13 CO₂ tracer study
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Drake, John E., Furze, Morgan E., Tjoelker, Mark G., Carrillo, Yolima, Barton, Craig V. M., and Pendall, Elise
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- 2019
5. The fate of carbon in a mature forest under carbon dioxide enrichment
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Jiang, Mingkai, Medlyn, Belinda E., Drake, John E., Duursma, Remko A., Anderson, Ian C., Barton, Craig V. M., and Boer, Matthias M.
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Atmospheric carbon dioxide -- Supply and demand -- Forecasts and trends ,Old growth forests -- Forecasts and trends -- Environmental aspects -- Australia ,Forest carbon -- Analysis -- Forecasts and trends -- Environmental aspects ,Carbon fixation -- Analysis -- Forecasts and trends -- Environmental aspects ,Market trend/market analysis ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
Atmospheric carbon dioxide enrichment (eCO.sub.2) can enhance plant carbon uptake and growth.sup.1-5, thereby providing an important negative feedback to climate change by slowing the rate of increase of the atmospheric CO.sub.2 concentration.sup.6. Although evidence gathered from young aggrading forests has generally indicated a strong CO.sub.2 fertilization effect on biomass growth.sup.3-5, it is unclear whether mature forests respond to eCO.sub.2 in a similar way. In mature trees and forest stands.sup.7-10, photosynthetic uptake has been found to increase under eCO.sub.2 without any apparent accompanying growth response, leaving the fate of additional carbon fixed under eCO.sub.2 unclear.sup.4,5,7-11. Here using data from the first ecosystem-scale Free-Air CO.sub.2 Enrichment (FACE) experiment in a mature forest, we constructed a comprehensive ecosystem carbon budget to track the fate of carbon as the forest responded to four years of eCO.sub.2 exposure. We show that, although the eCO.sub.2 treatment of +150 parts per million (+38 per cent) above ambient levels induced a 12 per cent (+247 grams of carbon per square metre per year) increase in carbon uptake through gross primary production, this additional carbon uptake did not lead to increased carbon sequestration at the ecosystem level. Instead, the majority of the extra carbon was emitted back into the atmosphere via several respiratory fluxes, with increased soil respiration alone accounting for half of the total uptake surplus. Our results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under eCO.sub.2, and challenge the efficacy of climate mitigation strategies that rely on ubiquitous CO.sub.2 fertilization as a driver of increased carbon sinks in global forests. Carbon dioxide enrichment of a mature forest resulted in the emission of the excess carbon back into the atmosphere via enhanced ecosystem respiration, suggesting that mature forests may be limited in their capacity to mitigate climate change., Author(s): Mingkai Jiang [sup.1] , Belinda E. Medlyn [sup.1] , John E. Drake [sup.1] [sup.2] , Remko A. Duursma [sup.1] , Ian C. Anderson [sup.1] , Craig V. M. Barton [...]
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- 2020
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6. Elevated atmospheric carbon dioxide concentrations promote ant tending of aphids
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Kremer, Jenni M. M., Nooten, Sabine S., Cook, James M., Ryalls, James M. W., Barton, Craig V. M., and Johnson, Scott N.
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- 2018
7. Optimal stomatal theory predicts <scp> CO 2 </scp> responses of stomatal conductance in both gymnosperm and angiosperm trees
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Anna Gardner, Mingkai Jiang, David S. Ellsworth, A. Robert MacKenzie, Jeremy Pritchard, Martin Karl‐Friedrich Bader, Craig V. M. Barton, Carl Bernacchi, Carlo Calfapietra, Kristine Y. Crous, Mirindi Eric Dusenge, Teresa E. Gimeno, Marianne Hall, Shubhangi Lamba, Sebastian Leuzinger, Johan Uddling, Jeffrey Warren, Göran Wallin, and Belinda E. Medlyn
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evergreen ,climate change ,photosynthesis ,Physiology ,free-air CO enrichment 2 ,water-use efficiency ,Plant Science ,deciduous - Abstract
Optimal stomatal theory predicts that stomata operate to maximise photosynthesis (Anet) and minimise transpirational water loss to achieve optimal intrinsic water-use efficiency (iWUE). We tested whether this theory can predict stomatal responses to elevated atmospheric CO2 (eCO2), and whether it can capture differences in responsiveness among woody plant functional types (PFTs). We conducted a meta-analysis of tree studies of the effect of eCO2 on iWUE and its components Anet and stomatal conductance (gs). We compared three PFTs, using the unified stomatal optimisation (USO) model to account for confounding effects of leaf–air vapour pressure difference (D). We expected smaller gs, but greater Anet, responses to eCO2 in gymnosperms compared with angiosperm PFTs. We found that iWUE increased in proportion to increasing eCO2 in all PFTs, and that increases in Anet had stronger effects than reductions in gs. The USO model correctly captured stomatal behaviour with eCO2 across most datasets. The chief difference among PFTs was a lower stomatal slope parameter (g1) for the gymnosperm, compared with angiosperm, species. Land surface models can use the USO model to describe stomatal behaviour under changing atmospheric CO2 conditions. AG gratefully acknowledges a studentship provided by the John Horseman Trust and the University of Birmingham. The BIFoR FACE facility is supported by the JABBS Foundation, the University of Birmingham and the John Horseman Trust. ARMK acknowledges support from the UK Natural Environment Research Council through grant NE/S015833/1. MJ and BEM acknowledge funding from the Australian Research Council (DE210101654, FL190100003).
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- 2022
8. Elevated atmosphericCO 2suppresses silicon accumulation and exacerbates endophyte reductions in plant phosphorus
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Johnson, Scott N., primary, Barton, Craig V. M., additional, Biru, Fikadu N., additional, Islam, Tarikul, additional, Mace, Wade J., additional, Rowe, Rhiannon C., additional, and Cibils–Stewart, Ximena, additional
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- 2023
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9. Optimal stomatal theory predicts CO2 responses of stomatal conductance in both gymnosperm and angiosperm trees
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Gardner, Anna, Jiang, Mingkai, Ellsworth, David S., MacKenzie, A. Robert, Pritchard, Jeremy, Bader, Martin K.-F., Barton, Craig V. M., Bernacchi, Carl, Calfapietra, Carlo, Crous, Kristine Y., Dusenge, Mirindi Eric, Gimeno, Teresa E., Hall, Marianne, Lamba, Shubhangi, Leuzinger, Sebastian, Uddling, Johan, Warren, Jeffrey, Wallin, Göran, Medlyn, Belinda E., Gardner, Anna, Jiang, Mingkai, Ellsworth, David S., MacKenzie, A. Robert, Pritchard, Jeremy, Bader, Martin K.-F., Barton, Craig V. M., Bernacchi, Carl, Calfapietra, Carlo, Crous, Kristine Y., Dusenge, Mirindi Eric, Gimeno, Teresa E., Hall, Marianne, Lamba, Shubhangi, Leuzinger, Sebastian, Uddling, Johan, Warren, Jeffrey, Wallin, Göran, and Medlyn, Belinda E.
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Optimal stomatal theory predicts that stomata operate to maximise photosynthesis (A(net)) and minimise transpirational water loss to achieve optimal intrinsic water-use efficiency (iWUE). We tested whether this theory can predict stomatal responses to elevated atmospheric CO2 (eCO(2)), and whether it can capture differences in responsiveness among woody plant functional types (PFTs). We conducted a meta-analysis of tree studies of the effect of eCO(2) on iWUE and its components A(net) and stomatal conductance (g(s)). We compared three PFTs, using the unified stomatal optimisation (USO) model to account for confounding effects of leaf-air vapour pressure difference (D). We expected smaller g(s), but greater A(net), responses to eCO(2) in gymnosperms compared with angiosperm PFTs. We found that iWUE increased in proportion to increasing eCO(2) in all PFTs, and that increases in A(net) had stronger effects than reductions in g(s). The USO model correctly captured stomatal behaviour with eCO(2) across most datasets. The chief difference among PFTs was a lower stomatal slope parameter (g(1)) for the gymnosperm, compared with angiosperm, species. Land surface models can use the USO model to describe stomatal behaviour under changing atmospheric CO2 conditions.
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- 2023
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10. Effects of elevated atmospheric carbon dioxide concentration on growth and physiology of Sitka spruce (Picea sitchensis (Bong.) Carr.)
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Barton, Craig V. M.
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571.2 - Abstract
The aim of this thesis is defined by the title, and two experimental approaches were used to investigate different aspects of the effect of elevated [CO2] on Sitka spruce; firstly the long term effect on mature tissue using branch bags and secondly, the interaction between [CO2] and nutrient supply rate on the growth and physiology of seedling trees. Six branches of six 16 year-old Sitka spruce trees were continuously exposed to elevated [CO2] (700 μmol mol-1) for four years. Branch growth, shoot numbers, needle size, stomatal density, nutrient and carbohydrate concentration, photosynthesis and stomatal conductance were measured throughout the experiment. There was no effect of elevated [CO2] on the growth of the branches or needles, or on the nutrient or carbohydrate concentrations of needles. Neither was there evidence for an acclimation of photosynthesis or stomatal conductance to growth in elevated [CO2] in current year needles. However, there was some down-regulation of photosynthesis in one-year old needles coincident with an increase in soluble carbohydrate concentration. In a second experiment one-year old seedlings were re-potted into sand and grown for eight months in open-top chambers in either ambient or 700 μmol mol-1 [CO2]. They were supplied with nutrients at two rates: a high rate designed to permit maximum growth rate, and a low rate 1/10 the high rate. Growth was measured each week and six harvests were made during the experiment. A purpose built whole-tree gas exchange system was used to measure independently above and below ground CO2 fluxes over 24 hours. Shoot photosynthesis responses to [CO2] and needle nutrient and carbohydrate concentrations were also measured. Elevated [CO2] enhanced growth and increased allocation to roots at both high and low nutrient supply rates, but growth enhancement was larger at the high nutrient supply rate.
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- 1997
11. Elevated atmospheric <scp> CO 2 </scp> suppresses silicon accumulation and exacerbates endophyte reductions in plant phosphorus
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Scott N. Johnson, Craig V. M. Barton, Fikadu N. Biru, Tarikul Islam, Wade J. Mace, Rhiannon C. Rowe, and Ximena Cibils–Stewart
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Ecology, Evolution, Behavior and Systematics - Published
- 2023
12. Optimal stomatal theory predictsCO 2responses of stomatal conductance in both gymnosperm and angiosperm trees
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Gardner, Anna, primary, Jiang, Mingkai, additional, Ellsworth, David S., additional, MacKenzie, A. Robert, additional, Pritchard, Jeremy, additional, Bader, Martin Karl‐Friedrich, additional, Barton, Craig V. M., additional, Bernacchi, Carl, additional, Calfapietra, Carlo, additional, Crous, Kristine Y., additional, Dusenge, Mirindi Eric, additional, Gimeno, Teresa E., additional, Hall, Marianne, additional, Lamba, Shubhangi, additional, Leuzinger, Sebastian, additional, Uddling, Johan, additional, Warren, Jeffrey, additional, Wallin, Göran, additional, and Medlyn, Belinda E., additional
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- 2022
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13. Tapping into the physiological responses to mistletoe infection during heat and drought stress
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H. N. Speckman, Daniel Metzen, Chelsea Maier, Craig V. M. Barton, Matthias M. Boer, Anne Griebel, Elise Pendall, Brendan Choat, Jennifer M. R. Peters, and Rachael H. Nolan
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Hot Temperature ,biology ,Physiology ,Vapour Pressure Deficit ,fungi ,Water ,Xylem ,Plant Science ,biology.organism_classification ,Eucalyptus ,Droughts ,Mistletoe ,Eucalyptus fibrosa ,Agronomy ,Soil water ,Eucalyptus moluccana ,Water use ,Transpiration - Abstract
Mistletoes are important co-contributors to tree mortality globally, particularly during droughts. In Australia, mistletoe distributions are expanding in temperate woodlands, while their hosts have experienced unprecedented heat and drought stress in recent years. We investigated whether the excessive water use of mistletoes increased the probability of xylem emboli in a mature woodland during the recent record drought that was compounded by multiple heatwaves. We continuously recorded transpiration ($T_{SLA}$) of infected and uninfected branches from two eucalypt species over two summers, monitored stem and leaf water potentials ($\Psi $) and used hydraulic vulnerability curves to estimate percent loss in conductivity (PLC) for each species. Variations in weather (vapor pressure deficit, photosynthetically active radiation, soil water content), host species and % mistletoe foliage explained 78% of hourly $T_{SLA}$. While mistletoe acted as an uncontrollable sink for water in the host even during typical summer days, daily $T_{SLA}$ increased up to 4-fold in infected branches on hot days, highlighting the previously overlooked importance of temperature stress in amplifying water loss in mistletoes. The increased water use of mistletoes resulted in significantly decreased host $\Psi _{\rm{leaf}}$ and $\Psi _{\rm{trunk}}$. It further translated to an estimated increase of up to 11% PLC for infected hosts, confirming greater hydraulic dysfunction of infected trees that place them at higher risk of hydraulic failure. However, uninfected branches of Eucalyptus fibrosa F.Muell. had much tighter controls on water loss than uninfected branches of Eucalyptus moluccana Roxb., which shifted the risk of hydraulic failure towards an increased risk of carbon starvation for E. fibrosa. The contrasting mechanistic responses to heat and drought stress between both co-occurring species demonstrates the complexity of host–parasite interactions and highlights the challenge in predicting species-specific responses to biotic agents in a warmer and drier climate.
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- 2021
14. Elevated atmospheric CO2 suppresses silicon accumulation and exacerbates endophyte reductions in plant phosphorus.
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Johnson, Scott N., Barton, Craig V. M., Biru, Fikadu N., Islam, Tarikul, Mace, Wade J., Rowe, Rhiannon C., and Cibils–Stewart, Ximena
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ATMOSPHERIC carbon dioxide , *ENDOPHYTIC fungi , *PHOSPHORUS , *PHOTOSYNTHETIC rates , *PLANT productivity , *TALL fescue , *GRASSES - Abstract
Many temperate grasses are both hyper‐accumulators of silicon (Si) and hosts of Epichloë fungal endophytes, functional traits which may alleviate environmental stresses such as herbivore attack. Si accumulation and endophyte infection may operate synergistically, but this has not been tested in a field setting, nor in the context of changing environmental conditions. Predicted increases in atmospheric CO2 concentrations can affect both Si accumulation and endophyte function, but these have not been studied in combination.We investigated how elevated atmospheric CO2 (eCO2), Si supplementation, endophyte‐presence and insect herbivory impacted plant growth, stoichiometry (C, N, P and Si), leaf gas exchange (rates of photosynthesis, stomatal conductance, transpiration rates) and endophyte production of anti‐herbivore defences (alkaloids) of an important pasture grass (tall fescue; Lolium arundinaceum) in the field.eCO2 and Si supplementation increased shoot biomass (+52% and +31%, respectively), whereas herbivory reduced shoot biomass by at least 35% and induced Si accumulation by 24%. Shoot Si concentrations, in contrast, decreased by 17%–21% under eCO2. Si supplementation and herbivory reduced shoot C concentrations. eCO2 reduced shoot N concentrations which led to increased shoot C:N ratios. Overall, shoot P concentrations were 26% lower in endophytic plants compared to non‐endophytic plants, potentially due to decreased mass flow (i.e. observed reductions in stomatal conductance and transpiration). Alkaloid production was not discernibly affected by any experimental treatment. The negative impacts of endophytes on P uptake were particularly strong under eCO2.We show that eCO2 and insect herbivory reduce and promote Si accumulation, respectively, incorporating some field conditions for the first time. This indicates that these drivers operate in a more realistic ecological context than previously demonstrated. Reduced uptake of P in endophytic plants may adversely affect plant productivity in the future, particularly if increased demand for P due to improved plant growth under eCO2 cannot be met. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]
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- 2023
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15. Optimal stomatal theory predicts CO
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Anna, Gardner, Mingkai, Jiang, David S, Ellsworth, A Robert, MacKenzie, Jeremy, Pritchard, Martin Karl-Friedrich, Bader, Craig V M, Barton, Carl, Bernacchi, Carlo, Calfapietra, Kristine Y, Crous, Mirindi Eric, Dusenge, Teresa E, Gimeno, Marianne, Hall, Shubhangi, Lamba, Sebastian, Leuzinger, Johan, Uddling, Jeffrey, Warren, Göran, Wallin, and Belinda E, Medlyn
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Optimal stomatal theory predicts that stomata operate to maximise photosynthesis (A
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- 2022
16. Increasing aridity will not offset CO2fertilization in fast‐growing eucalypts with access to deep soil water
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Daniel Nadal-Sala, Belinda E. Medlyn, David T. Tissue, Craig V. M. Barton, David S. Ellsworth, Mark G. Tjoelker, Nadine K. Ruehr, Santi Sabaté, and Carles Gracia
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0106 biological sciences ,Limiting factor ,Global and Planetary Change ,Irrigation ,Eucalyptus saligna ,010504 meteorology & atmospheric sciences ,Ecology ,biology ,Vapour Pressure Deficit ,Primary production ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Nutrient ,Agronomy ,Soil water ,Environmental Chemistry ,Environmental science ,Soil horizon ,0105 earth and related environmental sciences ,General Environmental Science - Abstract
Rising atmospheric [CO2 ] (Ca ) generally enhances tree growth if nutrients are not limiting. However, reduced water availability and elevated evaporative demand may offset such fertilization. Trees with access to deep soil water may be able to mitigate such stresses and respond more positively to Ca . Here, we sought to evaluate how increased vapor pressure deficit and reduced precipitation are likely to modify the impact of elevated Ca (eCa ) on tree productivity in an Australian Eucalyptus saligna Sm. plantation with access to deep soil water. We parameterized a forest growth simulation model (GOTILWA+) using data from two field experiments on E. saligna: a 2-year whole-tree chamber experiment with factorial Ca (ambient =380, elevated =620 μmol mol-1 ) and watering treatments, and a 10-year stand-scale irrigation experiment. Model evaluation showed that GOTILWA+ can capture the responses of canopy C uptake to (1) rising vapor pressure deficit (D) under both Ca treatments; (2) alterations in tree water uptake from shallow and deep soil layers during soil dry-down; and (3) the impact of irrigation on tree growth. Simulations suggest that increasing Ca up to 700 μmol mol-1 alone would result in a 33% increase in annual gross primary production (GPP) and a 62% increase in biomass over 10 years. However, a combined 48% increase in D and a 20% reduction in precipitation would halve these values. Our simulations identify high D conditions as a key limiting factor for GPP. They also suggest that rising Ca will compensate for increasing aridity limitations in E. saligna trees with access to deep soil water under non-nutrient limiting conditions, thereby reducing the negative impacts of global warming upon this eucalypt species. Simulation models not accounting for water sources available to deep-rooting trees are likely to overestimate aridity impacts on forest productivity and C stocks.
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- 2021
17. Plant productivity is a key driver of soil respiration response to climate change in a nutrient-limited soil
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Catriona A. Macdonald, Brajesh K. Singh, Craig V. M. Barton, Remko A. Duursma, Amit N. Khachane, Bhupinder P. Singh, David S. Ellsworth, and Ian C. Anderson
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0106 biological sciences ,Biomass (ecology) ,biology ,Climate change ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Soil respiration ,chemistry.chemical_compound ,Nutrient ,Microbial population biology ,chemistry ,Productivity (ecology) ,Agronomy ,Seedling ,Carbon dioxide ,Environmental science ,Ecology, Evolution, Behavior and Systematics ,010606 plant biology & botany - Abstract
Despite knowledge of the interaction between climate change factors significant uncertainty exists concerning the individual and interactive effects of elevated carbon dioxide (eCO2) and elevated temperature (eT) on the soil microbiome and function. Here we examine the individual and interactive effects of eCO2 and eT on tree growth, soil respiration (Rsoil), biomass, structural and functional composition of microbial community, nitrogen (N) mineralisation and N availability in a whole tree chamber experiment. Eucalyptus globulus plants were grown from seedling to ca. 10 m tall for 15 months in a nutrient-poor sandy soil under ambient and elevated (+ 240 ppm) atmospheric CO2 concentrations combined with ambient or elevated temperatures (+ 3 °C) in a full factorial design. Plant growth was strongly stimulated under eCO2, but eT had little impact on any measured plant property. In contrast, Rsoil was not consistently affected by eCO2 or eT, but correlated strongly with root and leaf biomass. The response of N-mineralisation and nutrient availability to eCO2 and eT varied across time, and available N correlated strongly with plant height. Further, the C:N ratio of the microbial biomass and leaves were both higher under eCeT treatment. However, these functional measures were not significantly linked to either structural or functional diversity of the soil microbiome. Taken together, these results suggest that in this low-nutrient soil, belowground processes are principally driven by aboveground productivity. Our work provides novel insight into mechanisms underlying above- and belowground response to climate change, and the potential to sequester C in a low-nutrient status soil under future climatic conditions may be limited .
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- 2021
18. Ecotrons: Powerful and versatile ecosystem analysers for ecology, agronomy and environmental science
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George A. Kowalchuk, Jörg-Peter Schnitzler, Clément Piel, Wolfgang W. Weisser, Nicolas Brüggemann, Jean-François Le Galliard, Samuel Abiven, Stuart H Larsen, Teis Nørgaard Mikkelsen, Sarah Garré, Florent Massol, Hans J. De Boeck, Ivan Nijs, Joana Sauze, Bernard Longdoz, Alexandru Milcu, Natalie Beenaerts, Nico Eisenhauer, Timo Domisch, Matteo Dainese, Francois Rineau, Thomas Pütz, Richard L. Jasoni, Andrea Ghirardo, John A. Arnone, Leonardo H. Teixeira, Vincent Leemans, Alban Gebler, Georg Niedrist, Damien Landais, Craig V. M. Barton, J. Barbro Winkler, Olivier Ravel, Jacques Roy, Mark G. Tjoelker, Anja Schmidt, Écotron Européen de Montpellier, Centre National de la Recherche Scientifique (CNRS), CEREEP-Ecotron Ile de France (UMS 3194), Département de Biologie - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'écologie et des sciences de l'environnement de Paris (iEES Paris ), Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Université Paul-Valéry - Montpellier 3 (UPVM)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Sub Ecology and Biodiversity, Ecology and Biodiversity, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université Paul-Valéry - Montpellier 3 (UPVM)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro - Montpellier SupAgro, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), and Université Paul-Valéry - Montpellier 3 (UPVM)-École pratique des hautes études (EPHE)
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0106 biological sciences ,010504 meteorology & atmospheric sciences ,Process (engineering) ,Ecology (disciplines) ,Biodiversity ,010603 evolutionary biology ,01 natural sciences ,Natural (archaeology) ,Soil ,experimentation ,[SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems ,environmental simulations ,Environmental Science(all) ,ddc:570 ,Environmental Chemistry ,Ecosystem ,controlled environment facilities ,Biology ,global change ,biodiversity ,0105 earth and related environmental sciences ,General Environmental Science ,2. Zero hunger ,Global and Planetary Change ,Ecology ,[SDE.IE]Environmental Sciences/Environmental Engineering ,business.industry ,Environmental resource management ,Research Review ,Global change ,15. Life on land ,research infrastructures ,ecosystem process measurements ,ddc ,Variety (cybernetics) ,Chemistry ,13. Climate action ,Controlled Environment Facilities ,Ecosystem Functioning ,Ecosystem Process Measurements ,Environmental Simulations ,Experimentation ,Global Change ,Research Infrastructures ,ecosystem functioning ,Complementarity (molecular biology) ,Environmental Science ,Environmental science ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology ,business - Abstract
Ecosystems integrity and services are threatened by anthropogenic global changes. Mitigating and adapting to these changes require knowledge of ecosystem functioning in the expected novel environments, informed in large part through experimentation and modelling. This paper describes 13 advanced controlled environment facilities for experimental ecosystem studies, herein termed ecotrons, open to the international community. Ecotrons enable simulation of a wide range of natural environmental conditions in replicated and independent experimental units while measuring various ecosystem processes. This capacity to realistically control ecosystem environments is used to emulate a variety of climatic scenarios and soil conditions, in natural sunlight or through broad‐spectrum lighting. The use of large ecosystem samples, intact or reconstructed, minimizes border effects and increases biological and physical complexity. Measurements of concentrations of greenhouse trace gases as well as their net exchange between the ecosystem and the atmosphere are performed in most ecotrons, often quasi continuously. The flow of matter is often tracked with the use of stable isotope tracers of carbon and other elements. Equipment is available for measurements of soil water status as well as root and canopy growth. The experiments ran so far emphasize the diversity of the hosted research. Half of them concern global changes, often with a manipulation of more than one driver. About a quarter deal with the impact of biodiversity loss on ecosystem functioning and one quarter with ecosystem or plant physiology. We discuss how the methodology for environmental simulation and process measurements, especially in soil, can be improved and stress the need to establish stronger links with modelling in future projects. These developments will enable further improvements in mechanistic understanding and predictive capacity of ecotron research which will play, in complementarity with field experimentation and monitoring, a crucial role in exploring the ecosystem consequences of environmental changes., Experimentation and modelling are necessary to predict ecosystem functioning under future environments and to develop mitigating and adapting strategies. This paper describes 13 advanced controlled environment facilities, called ecotrons, open to the international community. An ecotron comprises a set of replicated enclosures designed to host ecosystems samples and enable realistic simulations of above‐ and belowground environmental conditions, while simultaneously and automatically measuring ecosystem processes. The characteristics of these infrastructures are given as well as examples of collaborative projects hosted so far.
- Published
- 2021
19. High safety margins to drought-induced hydraulic failure found in five pasture grasses
- Author
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Vinod Jacob, Brendan Choat, Amber C. Churchill, Haiyang Zhang, Craig V. M. Barton, Arjunan Krishnananthaselvan, Alison K. Post, Sally A. Power, Belinda E. Medlyn, and David T. Tissue
- Subjects
Plant Leaves ,Dehydration ,Physiology ,Xylem ,Embolism ,Plant Science ,Poaceae ,Droughts - Abstract
Determining the relationship between reductions in stomatal conductance (g
- Published
- 2022
20. Optimal stomatal theory predicts CO2 responses of stomatal conductance in both gymnosperm and angiosperm trees.
- Author
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Gardner, Anna, Jiang, Mingkai, Ellsworth, David S., MacKenzie, A. Robert, Pritchard, Jeremy, Bader, Martin Karl‐Friedrich, Barton, Craig V. M., Bernacchi, Carl, Calfapietra, Carlo, Crous, Kristine Y., Dusenge, Mirindi Eric, Gimeno, Teresa E., Hall, Marianne, Lamba, Shubhangi, Leuzinger, Sebastian, Uddling, Johan, Warren, Jeffrey, Wallin, Göran, and Medlyn, Belinda E.
- Subjects
STOMATA ,ATMOSPHERIC carbon dioxide ,WATER efficiency ,GYMNOSPERMS ,WEATHER - Abstract
Summary: Optimal stomatal theory predicts that stomata operate to maximise photosynthesis (Anet) and minimise transpirational water loss to achieve optimal intrinsic water‐use efficiency (iWUE). We tested whether this theory can predict stomatal responses to elevated atmospheric CO2 (eCO2), and whether it can capture differences in responsiveness among woody plant functional types (PFTs).We conducted a meta‐analysis of tree studies of the effect of eCO2 on iWUE and its components Anet and stomatal conductance (gs). We compared three PFTs, using the unified stomatal optimisation (USO) model to account for confounding effects of leaf–air vapour pressure difference (D). We expected smaller gs, but greater Anet, responses to eCO2 in gymnosperms compared with angiosperm PFTs.We found that iWUE increased in proportion to increasing eCO2 in all PFTs, and that increases in Anet had stronger effects than reductions in gs. The USO model correctly captured stomatal behaviour with eCO2 across most datasets. The chief difference among PFTs was a lower stomatal slope parameter (g1) for the gymnosperm, compared with angiosperm, species.Land surface models can use the USO model to describe stomatal behaviour under changing atmospheric CO2 conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
21. Advances in remote sensing of plant stress
- Author
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Barton, Craig V. M.
- Published
- 2012
22. High safety margins to drought‐induced hydraulic failure found in five pasture grasses
- Author
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Jacob, Vinod, primary, Choat, Brendan, additional, Churchill, Amber C., additional, Zhang, Haiyang, additional, Barton, Craig V. M., additional, Krishnananthaselvan, Arjunan, additional, Post, Alison K., additional, Power, Sally A., additional, Medlyn, Belinda E., additional, and Tissue, David T., additional
- Published
- 2022
- Full Text
- View/download PDF
23. Pastures and Climate Extremes: Impacts of Cool Season Warming and Drought on the Productivity of Key Pasture Species in a Field Experiment
- Author
-
Churchill, Amber C., primary, Zhang, Haiyang, additional, Fuller, Kathryn J., additional, Amiji, Burhan, additional, Anderson, Ian C., additional, Barton, Craig V. M., additional, Carrillo, Yolima, additional, Catunda, Karen L. M., additional, Chandregowda, Manjunatha H., additional, Igwenagu, Chioma, additional, Jacob, Vinod, additional, Kim, Gil Won, additional, Macdonald, Catriona A., additional, Medlyn, Belinda E., additional, Moore, Ben D., additional, Pendall, Elise, additional, Plett, Jonathan M., additional, Post, Alison K., additional, Powell, Jeff R., additional, Tissue, David T., additional, Tjoelker, Mark G., additional, and Power, Sally A., additional
- Published
- 2022
- Full Text
- View/download PDF
24. No evidence of homeostatic regulation of leaf temperature in Eucalyptus parramattensis trees: integration of CO 2 flux and oxygen isotope methodologies
- Author
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John E. Drake, Margaret M. Barbour, Richard Harwood, Craig V. M. Barton, Peter B. Reich, Mark G. Tjoelker, and Angelica Vårhammar
- Subjects
0106 biological sciences ,0301 basic medicine ,Physiology ,Vapour Pressure Deficit ,Chemistry ,Plant Science ,Thermoregulation ,Photosynthesis ,Atmospheric sciences ,01 natural sciences ,Degree (temperature) ,Carbon cycle ,03 medical and health sciences ,Light intensity ,030104 developmental biology ,Poikilotherm ,Homeothermy ,010606 plant biology & botany - Abstract
Thermoregulation of leaf temperature (Tleaf ) may foster metabolic homeostasis in plants, but the degree to which Tleaf is moderated, and under what environmental contexts, is a topic of debate. Isotopic studies inferred the temperature of photosynthetic carbon assimilation to be a constant value of c. 20°C; by contrast, leaf biophysical theory suggests a strong dependence of Tleaf on environmental drivers. Can this apparent disparity be reconciled? We continuously measured Tleaf and whole-crown net CO2 uptake for Eucalyptus parramattensis trees growing in field conditions in whole-tree chambers under ambient and +3°C warming conditions, and calculated assimilation-weighted leaf temperature (TL-AW ) across 265 d, varying in air temperature (Tair ) from -1 to 45°C. We compared these data to TL-AW derived from wood cellulose δ18 O. Tleaf exhibited substantial variation driven by Tair , light intensity, and vapor pressure deficit, and Tleaf was strongly linearly correlated with Tair with a slope of c. 1.0. TL-AW values calculated from cellulose δ18 O vs crown fluxes were remarkably consistent; both varied seasonally and in response to the warming treatment, tracking variation in Tair . The leaves studied here were nearly poikilothermic, with no evidence of thermoregulation of Tleaf towards a homeostatic value. Importantly, this work supports the use of cellulose δ18 O to infer TL-AW , but does not support the concept of strong homeothermic regulation of Tleaf.
- Published
- 2020
25. Does root respiration in Australian rainforest tree seedlings acclimate to experimental warming?
- Author
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Stefan K. Arndt, Kristine Y. Crous, Mark G. Tjoelker, Zineb Choury, Peter B. Reich, Elise Pendall, Nam Jin Noh, Jinquan Li, and Craig V. M. Barton
- Subjects
0106 biological sciences ,Rainforest ,Physiology ,Cellular respiration ,Acclimatization ,Biome ,Global warming ,Australia ,Temperature ,Q10 ,Plant Science ,15. Life on land ,Biology ,010603 evolutionary biology ,01 natural sciences ,Trees ,Degree (temperature) ,Plant Leaves ,Horticulture ,Seedlings ,Respiration ,010606 plant biology & botany - Abstract
Plant respiration can acclimate to changing environmental conditions and vary between species as well as biome types, although belowground respiration responses to ongoing climate warming are not well understood. Understanding the thermal acclimation capacity of root respiration (Rroot) in relation to increasing temperatures is therefore critical in elucidating a key uncertainty in plant function in response to warming. However, the degree of temperature acclimation of Rroot in rainforest trees and how root chemical and morphological traits are related to acclimation is unknown. Here we investigated the extent to which respiration of fine roots (≤2 mm) of four tropical and four warm-temperate rainforest tree seedlings differed in response to warmer growth temperatures (control and +6 °C), including temperature sensitivity (Q10) and the degree of acclimation of Rroot. Regardless of biome type, we found no consistent pattern in the short-term temperature responses of Rroot to elevated growth temperature: a significant reduction in the temperature response of Rroot to +6 °C treatment was only observed for a tropical species, Cryptocarya mackinnoniana, whereas the other seven species had either some stimulation or no alteration. Across species, Rroot was positively correlated with root tissue nitrogen concentration (mg g−1), while Q10 was positively correlated with root tissue density (g cm−3). Warming increased root tissue density by 20.8% but did not alter root nitrogen across species. We conclude that thermal acclimation capacity of Rroot to warming is species-specific and suggest that root tissue density is a useful predictor of Rroot and its thermal responses in rainforest tree seedlings.
- Published
- 2020
26. Pastures and Climate Extremes: Impacts of Cool Season Warming and Drought on the Productivity of Key Pasture Species in a Field Experiment
- Author
-
Amber C. Churchill, Haiyang Zhang, Kathryn J. Fuller, Burhan Amiji, Ian C. Anderson, Craig V. M. Barton, Yolima Carrillo, Karen L. M. Catunda, Manjunatha H. Chandregowda, Chioma Igwenagu, Vinod Jacob, Gil Won Kim, Catriona A. Macdonald, Belinda E. Medlyn, Ben D. Moore, Elise Pendall, Jonathan M. Plett, Alison K. Post, Jeff R. Powell, David T. Tissue, Mark G. Tjoelker, and Sally A. Power
- Subjects
Plant Science - Abstract
Shifts in the timing, intensity and/or frequency of climate extremes, such as severe drought and heatwaves, can generate sustained shifts in ecosystem function with important ecological and economic impacts for rangelands and managed pastures. The Pastures and Climate Extremes experiment (PACE) in Southeast Australia was designed to investigate the impacts of a severe winter/spring drought (60% rainfall reduction) and, for a subset of species, a factorial combination of drought and elevated temperature (ambient +3°C) on pasture productivity. The experiment included nine common pasture and Australian rangeland species from three plant functional groups (C3 grasses, C4 grasses and legumes) planted in monoculture. Winter/spring drought resulted in productivity declines of 45% on average and up to 74% for the most affected species (Digitaria eriantha) during the 6-month treatment period, with eight of the nine species exhibiting significant yield reductions. Despite considerable variation in species’ sensitivity to drought, C4 grasses were more strongly affected by this treatment than C3 grasses or legumes. Warming also had negative effects on cool-season productivity, associated at least partially with exceedance of optimum growth temperatures in spring and indirect effects on soil water content. The combination of winter/spring drought and year-round warming resulted in the greatest yield reductions. We identified responses that were either additive (Festuca), or less-than-additive (Medicago), where warming reduced the magnitude of drought effects. Results from this study highlight the sensitivity of diverse pasture species to increases in winter and spring drought severity similar to those predicted for this region, and that anticipated benefits of cool-season warming are unlikely to be realized. Overall, the substantial negative impacts on productivity suggest that future, warmer, drier climates will result in shortfalls in cool-season forage availability, with profound implications for the livestock industry and natural grazer communities.
- Published
- 2021
27. Belowground Responses to Increased Atmospheric CO2 Concentration in Birch (Betula Pendula Roth.)
- Author
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Rey, Ana, Barton, Craig V. M., Jarvis, Paul G., Mohren, G. M. J., editor, Kramer, K., editor, and Sabaté, S., editor
- Published
- 1997
- Full Text
- View/download PDF
28. Forest-scale sap flux responses to rainfall in a dryland eucalyptus plantation
- Author
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Morgan, Huw D. and Barton, Craig V. M.
- Published
- 2008
29. ERRATUM: Forest-scale sap flux responses to rainfall in a dryland eucalyptus plantation
- Author
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Morgan, Huw D. and Barton, Craig V. M.
- Published
- 2008
30. Green-Up and Brown-Down: Modelling Grassland Foliage Phenology Responses to Soil Moisture Availability
- Author
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Yang, Jinyan, primary, Medlyn, Belinda E., additional, Barton, Craig V. M., additional, Churchill, Amber C., additional, De Kauwe, Martin G., additional, Jiang, Mingkai, additional, Krishnananthaselvan, Arjunan, additional, Tissue, David T., additional, Pendall, Elise, additional, and Power, Sally A., additional
- Published
- 2022
- Full Text
- View/download PDF
31. Tapping into the physiological responses to mistletoe infection during heat and drought stress
- Author
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Griebel, Anne, primary, Peters, Jennifer M R, additional, Metzen, Daniel, additional, Maier, Chelsea, additional, Barton, Craig V M, additional, Speckman, Heather N, additional, Boer, Matthias M, additional, Nolan, Rachael H, additional, Choat, Brendan, additional, and Pendall, Elise, additional
- Published
- 2021
- Full Text
- View/download PDF
32. Climate warming and tree carbon use efficiency in a whole‐tree 13 <scp>CO</scp> 2 tracer study
- Author
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Elise Pendall, Craig V. M. Barton, John E. Drake, Yolima Carrillo, Mark G. Tjoelker, and Morgan E. Furze
- Subjects
2. Zero hunger ,0106 biological sciences ,0301 basic medicine ,Biomass (ecology) ,Physiology ,Global warming ,Heterotrophic respiration ,chemistry.chemical_element ,Primary production ,Plant Science ,15. Life on land ,01 natural sciences ,Acclimatization ,03 medical and health sciences ,030104 developmental biology ,chemistry ,Agronomy ,13. Climate action ,TRACER ,Respiration ,Environmental science ,Carbon ,010606 plant biology & botany - Abstract
Autotrophic respiration is a major driver of the global C cycle and may contribute a positive climate warming feedback through increased atmospheric concentrations of CO2 . The extent of this feedback depends on plants' ability to acclimate respiration to maintain a constant carbon use efficiency (CUE). We quantified respiratory partitioning of gross primary production (GPP) and CUE of field-grown trees in a long-term warming experiment (+3°C). We delivered a 13 C-CO2 pulse to whole tree crowns and chased that pulse in the respiration of leaves, whole crowns, roots, and soil. We also measured the isotopic composition of soil microbial biomass and the respiration rates of leaves and whole crowns. We documented homeostatic respiratory acclimation of foliar and whole-crown respiration rates; the trees adjusted to experimental warming such that leaf-level respiration rates were not increased. Experimental warming had no detectable impact on respiratory partitioning or mean residence times. Of the 13 C label acquired by the trees, aboveground respiration consumed 10%, belowground respiration consumed 40%, and the remaining 50% was retained. Experimental warming of +3°C did not alter respiratory partitioning at the scale of entire trees, suggesting that complete acclimation of respiration to warming is likely to dampen a positive climate warming feedback.
- Published
- 2019
33. The partitioning of gross primary production for young Eucalyptus tereticornis trees under experimental warming and altered water availability
- Author
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Michael J. Aspinwall, Peter B. Reich, Mark G. Tjoelker, Craig V. M. Barton, Sebastian Pfautsch, and John E. Drake
- Subjects
0106 biological sciences ,0301 basic medicine ,Maintenance respiration ,Physiology ,Primary production ,Plant Science ,15. Life on land ,01 natural sciences ,Acclimatization ,Accelerated Growth ,03 medical and health sciences ,030104 developmental biology ,Agronomy ,Soil water ,Respiration ,Environmental science ,Ecosystem ,Precipitation ,010606 plant biology & botany - Abstract
The allocation of carbon (C) is an important component of tree physiology that influences growth and ecosystem C storage. Allocation is challenging to measure, and its sensitivity to environmental changes such as warming and altered water availability is uncertain. We exposed young Eucalyptus tereticornis trees to +3°C warming and elimination of summer precipitation in the field using whole-tree chambers. We calculated C allocation terms using detailed measurements of growth and continuous whole-crown CO2 and water exchange measurements. Trees grew from small saplings to nearly 9 m height during this 15-month experiment. Warming accelerated growth and leaf area development, and it increased the partitioning of gross primary production (GPP) to aboveground respiration and growth while decreasing partitioning below ground. Eliminating summer precipitation reduced C gain and growth but did not impact GPP partitioning. Trees utilized deep soil water and avoided strongly negative water potentials. Warming increased growth respiration, but maintenance respiration acclimated homeostatically. The increasing growth in the warmed treatment resulted in higher rates of respiration, even with complete acclimation of maintenance respiration. Warming-induced stimulations of tree growth likely involve increased C allocation above ground, particularly to leaf area development, whereas reduced water availability may not stimulate allocation to roots.
- Published
- 2019
34. Ecotrons: Powerful and versatile ecosystem analysers for ecology, agronomy and environmental science
- Author
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Roy, Jacques, Rineau, François, De Boeck, Hans J, Nijs, Ivan, Pütz, Thomas, Abiven, Samuel, Arnone, John A, Barton, Craig V M, Beenaerts, Natalie, Brüggemann, Nicolas, Dainese, Matteo, Domisch, Timo, Eisenhauer, Nico, Garré, Sarah, Gebler, Alban, Ghirardo, Andrea, Jasoni, Richard L, Kowalchuk, George, Landais, Damien, Larsen, Stuart H, Leemans, Vincent, Le Galliard, Jean‐François, Longdoz, Bernard, Massol, Florent, Mikkelsen, Teis N, Niedrist, Georg, Piel, Clément, Ravel, Olivier, Sauze, Joana, Schmidt, Anja, et al, University of Zurich, and Roy, Jacques
- Subjects
2300 General Environmental Science ,Global and Planetary Change ,10122 Institute of Geography ,Ecology ,2304 Environmental Chemistry ,2306 Global and Planetary Change ,Environmental Chemistry ,910 Geography & travel ,2303 Ecology ,General Environmental Science - Published
- 2021
- Full Text
- View/download PDF
35. Increasing aridity will not offset CO$_{2}$ fertilization in fast-growing eucalypts with access to deep soil water
- Author
-
Nadal-Sala, Daniel, Medlyn, Belinda E., Ruehr, Nadine K., Barton, Craig V. M., Ellsworth, David S., Gracia, Carles, Tissue, David T., Tjoelker, Mark G., and Sabat��, Santi
- Subjects
Earth sciences ,ddc:550 - Abstract
Rising atmospheric [CO$_{2}$] (C$_{a}$) generally enhances tree growth if nutrients are not limiting. However, reduced water availability and elevated evaporative demand may offset such fertilization. Trees with access to deep soil water may be able to mitigate such stresses and respond more positively to C$_{a}$. Here, we sought to evaluate how increased vapor pressure deficit and reduced precipitation are likely to modify the impact of elevated C$_{a}$ (eC$_{a}$) on tree productivity in an Australian Eucalyptus saligna Sm. plantation with access to deep soil water. We parameterized a forest growth simulation model (GOTILWA+) using data from two field experiments on E. saligna: a 2���year whole���tree chamber experiment with factorial C$_{a}$ (ambient =380, elevated =620 ��mol mol$^{-1}$) and watering treatments, and a 10���year stand���scale irrigation experiment. Model evaluation showed that GOTILWA+ can capture the responses of canopy C uptake to (1) rising vapor pressure deficit (D) under both C$_{a}$ treatments; (2) alterations in tree water uptake from shallow and deep soil layers during soil dry���down; and (3) the impact of irrigation on tree growth. Simulations suggest that increasing C$_{a}$ up to 700 ��mol mol$^{-1}$ alone would result in a 33% increase in annual gross primary production (GPP) and a 62% increase in biomass over 10 years. However, a combined 48% increase in D and a 20% reduction in precipitation would halve these values. Our simulations identify high D conditions as a key limiting factor for GPP. They also suggest that rising Ca will compensate for increasing aridity limitations in E. saligna trees with access to deep soil water under non���nutrient limiting conditions, thereby reducing the negative impacts of global warming upon this eucalypt species. Simulation models not accounting for water sources available to deep���rooting trees are likely to overestimate aridity impacts on forest productivity and C stocks.
- Published
- 2021
36. Ecotrons: Powerful and versatile ecosystem analysers for ecology, agronomy and environmental science
- Author
-
Roy, Jacques; https://orcid.org/0000-0003-2275-9870, Rineau, François; https://orcid.org/0000-0002-5135-6184, De Boeck, Hans J; https://orcid.org/0000-0003-2180-8837, Nijs, Ivan; https://orcid.org/0000-0003-3111-680X, Pütz, Thomas; https://orcid.org/0000-0003-2101-448X, Abiven, Samuel; https://orcid.org/0000-0002-5663-0912, Arnone, John A; https://orcid.org/0000-0002-5114-3023, Barton, Craig V M; https://orcid.org/0000-0003-0085-0534, Beenaerts, Natalie; https://orcid.org/0000-0001-5655-5943, Brüggemann, Nicolas; https://orcid.org/0000-0003-3851-2418, Dainese, Matteo; https://orcid.org/0000-0001-7052-5572, Domisch, Timo; https://orcid.org/0000-0001-7026-1087, Eisenhauer, Nico; https://orcid.org/0000-0002-0371-6720, Garré, Sarah; https://orcid.org/0000-0001-9025-5282, Gebler, Alban; https://orcid.org/0000-0002-7189-1571, Ghirardo, Andrea; https://orcid.org/0000-0003-1973-4007, Jasoni, Richard L; https://orcid.org/0000-0002-2657-5625, Kowalchuk, George; https://orcid.org/0000-0003-3866-0832, Landais, Damien, Larsen, Stuart H; https://orcid.org/0000-0002-4595-4858, Leemans, Vincent, Le Galliard, Jean‐François; https://orcid.org/0000-0002-5965-9868, Longdoz, Bernard; https://orcid.org/0000-0002-7737-8226, Massol, Florent; https://orcid.org/0000-0001-5017-121X, Mikkelsen, Teis N; https://orcid.org/0000-0001-7470-6522, Niedrist, Georg; https://orcid.org/0000-0002-7511-6273, Piel, Clément; https://orcid.org/0000-0002-2003-5759, Ravel, Olivier, Sauze, Joana; https://orcid.org/0000-0001-8095-299X, Schmidt, Anja; https://orcid.org/0000-0001-5339-219X, et al, Roy, Jacques; https://orcid.org/0000-0003-2275-9870, Rineau, François; https://orcid.org/0000-0002-5135-6184, De Boeck, Hans J; https://orcid.org/0000-0003-2180-8837, Nijs, Ivan; https://orcid.org/0000-0003-3111-680X, Pütz, Thomas; https://orcid.org/0000-0003-2101-448X, Abiven, Samuel; https://orcid.org/0000-0002-5663-0912, Arnone, John A; https://orcid.org/0000-0002-5114-3023, Barton, Craig V M; https://orcid.org/0000-0003-0085-0534, Beenaerts, Natalie; https://orcid.org/0000-0001-5655-5943, Brüggemann, Nicolas; https://orcid.org/0000-0003-3851-2418, Dainese, Matteo; https://orcid.org/0000-0001-7052-5572, Domisch, Timo; https://orcid.org/0000-0001-7026-1087, Eisenhauer, Nico; https://orcid.org/0000-0002-0371-6720, Garré, Sarah; https://orcid.org/0000-0001-9025-5282, Gebler, Alban; https://orcid.org/0000-0002-7189-1571, Ghirardo, Andrea; https://orcid.org/0000-0003-1973-4007, Jasoni, Richard L; https://orcid.org/0000-0002-2657-5625, Kowalchuk, George; https://orcid.org/0000-0003-3866-0832, Landais, Damien, Larsen, Stuart H; https://orcid.org/0000-0002-4595-4858, Leemans, Vincent, Le Galliard, Jean‐François; https://orcid.org/0000-0002-5965-9868, Longdoz, Bernard; https://orcid.org/0000-0002-7737-8226, Massol, Florent; https://orcid.org/0000-0001-5017-121X, Mikkelsen, Teis N; https://orcid.org/0000-0001-7470-6522, Niedrist, Georg; https://orcid.org/0000-0002-7511-6273, Piel, Clément; https://orcid.org/0000-0002-2003-5759, Ravel, Olivier, Sauze, Joana; https://orcid.org/0000-0001-8095-299X, Schmidt, Anja; https://orcid.org/0000-0001-5339-219X, and et al
- Abstract
Ecosystems integrity and services are threatened by anthropogenic global changes. Mitigating and adapting to these changes require knowledge of ecosystem functioning in the expected novel environments, informed in large part through experimentation and modelling. This paper describes 13 advanced controlled environment facilities for experimental ecosystem studies, herein termed ecotrons, open to the international community. Ecotrons enable simulation of a wide range of natural environmental conditions in replicated and independent experimental units while measuring various ecosystem processes. This capacity to realistically control ecosystem environments is used to emulate a variety of climatic scenarios and soil conditions, in natural sunlight or through broad‐spectrum lighting. The use of large ecosystem samples, intact or reconstructed, minimizes border effects and increases biological and physical complexity. Measurements of concentrations of greenhouse trace gases as well as their net exchange between the ecosystem and the atmosphere are performed in most ecotrons, often quasi continuously. The flow of matter is often tracked with the use of stable isotope tracers of carbon and other elements. Equipment is available for measurements of soil water status as well as root and canopy growth. The experiments ran so far emphasize the diversity of the hosted research. Half of them concern global changes, often with a manipulation of more than one driver. About a quarter deal with the impact of biodiversity loss on ecosystem functioning and one quarter with ecosystem or plant physiology. We discuss how the methodology for environmental simulation and process measurements, especially in soil, can be improved and stress the need to establish stronger links with modelling in future projects. These developments will enable further improvements in mechanistic understanding and predictive capacity of ecotron research which will play, in complementarity with field experimenta
- Published
- 2021
37. Pastures and Climate Extremes: Impacts of cool season warming and drought on the productivity of key pasture species in a field experiment
- Author
-
Ian C. Anderson, Alison K. Post, Amber C. Churchill, Chioma Igwenagu, Catriona A. Macdonald, Benjamin D. Moore, Belinda E. Medlyn, Karen L. M. Catunda, Yolima Carrillo, Vinod Jacob, Burhan Amiji, Sally A. Power, Jonathan M. Plett, Elise Pendall, David T. Tissue, Kathryn J. Fuller, Jeff R. Powell, Gil Won Kim, Haiyang Zhang, Manjunatha H. Chandregowda, Mark G. Tjoelker, and Craig V. M. Barton
- Subjects
geography ,Biomass (ecology) ,geography.geographical_feature_category ,biology ,biology.organism_classification ,Pasture ,Agronomy ,Productivity (ecology) ,Environmental science ,Digitaria eriantha ,Ecosystem ,Monoculture ,Rangeland ,Annual percentage yield - Abstract
Shifts in the timing, intensity and/or frequency of climate extremes, such as severe drought and heatwaves, can generate sustained shifts in ecosystem function with important ecological and economic impacts for rangelands and managed pastures. The Pastures and Climate Extremes experiment (PACE) in Southeast Australia was designed to investigate the impacts of a severe winter/spring drought (60% rainfall reduction) and, for a subset of species, a factorial combination of drought and elevated temperature (ambient +3 °C) on pasture productivity. The experiment included nine common pasture and Australian rangeland species from three plant functional groups (C3 grasses, C4 grasses and legumes) planted in monoculture. Winter/spring drought resulted in productivity declines of 45% on average and up to 74% for the most affected species (Digitaria eriantha) during the 6-month treatment period, with eight of the nine species exhibiting significant yield reductions. Despite considerable variation in species’ sensitivity to drought, C4 grasses were more strongly affected by this treatment than C3 grasses or legumes. Warming also had negative effects on cool-season productivity, associated at least partially with exceedance of optimum growth temperatures in spring and indirect effects on soil water content. The combination of winter/spring drought and year-round warming resulted in the greatest yield reductions. We identified responses that were either additive such that there was only as significant warming effect under drought (Festuca), or less-than-additive, where there was no drought effect under warming (Medicago), compared to ambient plots. Results from this study highlight the sensitivity of diverse pasture species to increases in winter and spring drought severity similar to those predicted for this region, and that anticipated benefits of cool-season warming are unlikely to be realised. Overall, the substantial negative impacts on productivity suggest that future, warmer, drier climates will result in shortfalls in cool-season forage availability, with profound implications for the livestock industry and natural grazer communities.
- Published
- 2020
38. Increasing aridity will not offset CO
- Author
-
Daniel, Nadal-Sala, Belinda E, Medlyn, Nadine K, Ruehr, Craig V M, Barton, David S, Ellsworth, Carles, Gracia, David T, Tissue, Mark G, Tjoelker, and Santi, Sabaté
- Subjects
Plant Leaves ,Soil ,Fertilization ,Australia ,Water ,Carbon Dioxide ,Trees - Abstract
Rising atmospheric [CO
- Published
- 2020
39. Increasing aridity will not offset CO2fertilization in fast‐growing eucalypts with access to deep soil water
- Author
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Nadal‐Sala, Daniel, primary, Medlyn, Belinda E., additional, Ruehr, Nadine K., additional, Barton, Craig V. M., additional, Ellsworth, David S., additional, Gracia, Carles, additional, Tissue, David T., additional, Tjoelker, Mark G., additional, and Sabaté, Santi, additional
- Published
- 2021
- Full Text
- View/download PDF
40. Whole-tree mesophyll conductance reconciles isotopic and gas-exchange estimates of water-use efficiency
- Author
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Craig V. M. Barton, Courtney E. Campany, Mark G. Tjoelker, Nerea Ubierna, John D. Marshall, John E. Drake, and Teresa E. Gimeno
- Subjects
0106 biological sciences ,0301 basic medicine ,Physiology ,Plant Science ,Photosynthesis ,01 natural sciences ,Trees ,03 medical and health sciences ,Respiration ,Water cycle ,Water-use efficiency ,Carbon Isotopes ,Direct effects ,Conductance ,Water ,15. Life on land ,Carbon Dioxide ,Eucalyptus ,Plant Leaves ,030104 developmental biology ,Agronomy ,13. Climate action ,Environmental science ,Phloem ,Mesophyll Cells ,010606 plant biology & botany - Abstract
Photosynthetic water-use efficiency (WUE) describes the link between terrestrial carbon (C) and water cycles. Estimates of intrinsic WUE (iWUE) from gas exchange and C isotopic composition (δ13 C) differ due to an internal conductance in the leaf mesophyll (gm ) that is variable and seldom computed. We present the first direct estimates of whole-tree gm , together with iWUE from whole-tree gas exchange and δ13 C of the phloem (δ13 Cph ). We measured gas exchange, online 13 C-discrimination, and δ13 Cph monthly throughout spring, summer, and autumn in Eucalyptus tereticornis grown in large whole-tree chambers. Six trees were grown at ambient temperatures and six at a 3°C warmer air temperature; a late-summer drought was also imposed. Drought reduced whole-tree gm . Warming had few direct effects, but amplified drought-induced reductions in whole-tree gm . Whole-tree gm was similar to leaf gm for these same trees. iWUE estimates from δ13 Cph agreed with iWUE from gas exchange, but only after incorporating gm . δ13 Cph was also correlated with whole-tree 13 C-discrimination, but offset by -2.5 ± 0.7‰, presumably due to post-photosynthetic fractionations. We conclude that δ13 Cph is a good proxy for whole-tree iWUE, with the caveats that post-photosynthetic fractionations and intrinsic variability of gm should be incorporated to provide reliable estimates of this trait in response to abiotic stress.
- Published
- 2020
41. Seasonal responses of xylem sap velocity to VPD and solar radiation during drought in a stand of native trees in temperate Australia
- Author
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Melanie J. B. Zeppel, Derek Eamus, Brad R. Murray, and Craig V. M. Barton
- Subjects
Eucalyptus crebra ,Ecophysiology ,biology ,Callitris ,Vapour Pressure Deficit ,Plant Biology & Botany ,Xylem ,Plant Science ,Vegetation ,biology.organism_classification ,Atmospheric sciences ,Eucalyptus ,Botany ,Physics::Space Physics ,Temperate climate ,Agronomy and Crop Science ,Physics::Atmospheric and Oceanic Physics - Abstract
Xylem sap velocity of two dominant tree species, Eucalyptus crebra F. Muell. and Callitris glaucophylla J. Thompson & L.A.S. Johnson, in a native remnant forest of eastern Australia was measured in winter and summer during a prolonged (> 12 months) and extensive drought. The influence of vapour pressure deficit (VPD) and solar radiation levels on the velocity of sap was determined. Pronounced hysteresis in sap velocity was observed in both species as a function of VPD and solar radiation. However, the rotation of the hysteresis curve was clockwise for the response of sap velocity to VPD but anti-clockwise in the response of sap velocity to radiation levels. A possible reason for this difference is discussed.The degree of hysteresis (area bounded by the curve) was larger for the VPD response than the response to solar radiation and also varied with season. A simple linear model was able to predict sap velocity from knowledge of VPD and solar radiation in winter and summer. The consistent presence of hysteresis in the response to sap velocity to VPD and solar radiation suggests that large temporal and spatial models of vegetation water use may require some provision for the different responses of sap velocity, and hence water use, to VPD and solar radiation, between morning and afternoon and between seasons.
- Published
- 2020
42. The fate of carbon in a mature forest under carbon dioxide enrichment
- Author
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Belinda E. Medlyn, Kristine Y. Crous, Sally A. Power, Peter B. Reich, Teresa E. Gimeno, Catriona A. Macdonald, Bruna Marques dos Santos, Scott N. Johnson, Brajesh K. Singh, David S. Ellsworth, Riikka Rinnan, Elise Pendall, Luke Collins, Andrew N. Gherlenda, Jinyan Yang, Yolima Carrillo, Elizabeth H.J. Neilson, Ian C. Anderson, Mark G. Tjoelker, Laura Castañeda-Gómez, Sönke Zaehle, Uffe N. Nielsen, John E. Drake, K. Mahmud, Sarah L. Facey, Raúl Ochoa-Hueso, Craig V. M. Barton, Agnieszka Wujeska-Klause, Benjamin Smith, Remko A. Duursma, Jeff R. Powell, Paul D. Rymer, Matthias M. Boer, Jennifer K. M. Walker, Kathryn M. Emmerson, Nam Jin Noh, Loïc Nazaries, Shun Hasegawa, Juan Piñeiro, Johanna Pihlblad, Varsha S. Pathare, Martin G. De Kauwe, Roberto L. Salomón, Ülo Niinemets, Mingkai Jiang, Markus Riegler, Alexandre A. Renchon, Astrid Kännaste, and Ben D. Moore
- Subjects
0106 biological sciences ,Carbon Sequestration ,010504 meteorology & atmospheric sciences ,chemistry.chemical_element ,Forests ,Carbon sequestration ,Global Warming ,Models, Biological ,010603 evolutionary biology ,01 natural sciences ,Trees ,Carbon cycle ,Soil respiration ,Soil ,chemistry.chemical_compound ,Biomass ,Photosynthesis ,0105 earth and related environmental sciences ,Eucalyptus ,Carbon dioxide in Earth's atmosphere ,Multidisciplinary ,Atmosphere ,Carbon sink ,Carbon Dioxide ,chemistry ,Agronomy ,Carbon dioxide ,Environmental science ,New South Wales ,Ecosystem respiration ,Carbon - Abstract
Atmospheric carbon dioxide enrichment (eCO2) can enhance plant carbon uptake and growth1–5, thereby providing an important negative feedback to climate change by slowing the rate of increase of the atmospheric CO2 concentration6. Although evidence gathered from young aggrading forests has generally indicated a strong CO2 fertilization effect on biomass growth3–5, it is unclear whether mature forests respond to eCO2 in a similar way. In mature trees and forest stands7–10, photosynthetic uptake has been found to increase under eCO2 without any apparent accompanying growth response, leaving the fate of additional carbon fixed under eCO2 unclear4,5,7–11. Here using data from the first ecosystem-scale Free-Air CO2 Enrichment (FACE) experiment in a mature forest, we constructed a comprehensive ecosystem carbon budget to track the fate of carbon as the forest responded to four years of eCO2 exposure. We show that, although the eCO2 treatment of +150 parts per million (+38 per cent) above ambient levels induced a 12 per cent (+247 grams of carbon per square metre per year) increase in carbon uptake through gross primary production, this additional carbon uptake did not lead to increased carbon sequestration at the ecosystem level. Instead, the majority of the extra carbon was emitted back into the atmosphere via several respiratory fluxes, with increased soil respiration alone accounting for half of the total uptake surplus. Our results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under eCO2, and challenge the efficacy of climate mitigation strategies that rely on ubiquitous CO2 fertilization as a driver of increased carbon sinks in global forests. Carbon dioxide enrichment of a mature forest resulted in the emission of the excess carbon back into the atmosphere via enhanced ecosystem respiration, suggesting that mature forests may be limited in their capacity to mitigate climate change.
- Published
- 2020
43. No evidence of homeostatic regulation of leaf temperature in Eucalyptus parramattensis trees: integration of CO
- Author
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John E, Drake, Richard, Harwood, Angelica, Vårhammar, Margaret M, Barbour, Peter B, Reich, Craig V M, Barton, and Mark G, Tjoelker
- Subjects
Plant Leaves ,Eucalyptus ,Temperature ,Homeostasis ,Carbon Dioxide ,Oxygen Isotopes ,Photosynthesis ,Trees - Abstract
Thermoregulation of leaf temperature (T
- Published
- 2019
44. Upside-down fluxes Down Under: CO2 net sink in winter and net source in summer in a temperate evergreen broadleaf forest
- Author
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Belinda E. Medlyn, Matthias M. Boer, Daniel Metzen, Elise Pendall, Chelsea Maier, Craig V. M. Barton, Remko A. Duursma, Christopher B. Williams, Anne Griebel, Víctor Resco de Dios, David T. Tissue, Peter Isaac, and Alexandre A. Renchon
- Subjects
010504 meteorology & atmospheric sciences ,Vapour Pressure Deficit ,Eddy covariance ,04 agricultural and veterinary sciences ,Enhanced vegetation index ,15. Life on land ,Evergreen ,Atmospheric sciences ,01 natural sciences ,Light intensity ,13. Climate action ,040103 agronomy & agriculture ,Temperate climate ,0401 agriculture, forestry, and fisheries ,Environmental science ,Leaf area index ,Ecosystem respiration ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
Predicting the seasonal dynamics of ecosystem carbon fluxes is challenging in broadleaved evergreen forests because of their moderate climates and subtle changes in canopy phenology. We assessed the climatic and biotic drivers of the seasonality of net ecosystem–atmosphere CO2 exchange (NEE) of a eucalyptus-dominated forest near Sydney, Australia, using the eddy covariance method. The climate is characterised by a mean annual precipitation of 800 mm and a mean annual temperature of 18 ∘C, hot summers and mild winters, with highly variable precipitation. In the 4-year study, the ecosystem was a sink each year (−225 g C m−2 yr−1 on average, with a standard deviation of 108 g C m−2 yr−1); inter-annual variations were not related to meteorological conditions. Daily net C uptake was always detected during the cooler, drier winter months (June through August), while net C loss occurred during the warmer, wetter summer months (December through February). Gross primary productivity (GPP) seasonality was low, despite longer days with higher light intensity in summer, because vapour pressure deficit (D) and air temperature (Ta) restricted surface conductance during summer while winter temperatures were still high enough to support photosynthesis. Maximum GPP during ideal environmental conditions was significantly correlated with remotely sensed enhanced vegetation index (EVI; r2 = 0.46) and with canopy leaf area index (LAI; r2 = 0.29), which increased rapidly after mid-summer rainfall events. Ecosystem respiration (ER) was highest during summer in wet soils and lowest during winter months. ER had larger seasonal amplitude compared to GPP, and therefore drove the seasonal variation of NEE. Because summer carbon uptake may become increasingly limited by atmospheric demand and high temperature, and because ecosystem respiration could be enhanced by rising temperatures, our results suggest the potential for large-scale seasonal shifts in NEE in sclerophyll vegetation under climate change.
- Published
- 2018
45. Upside-down fluxes Down Under: CO2 net sink in winter and net source in summer in a temperate evergreen broadleaf forest
- Author
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Renchon, Alexandre A., Griebel, Anne, Metzen, Daniel, Williams, Christopher A., Medlyn, Belinda E., Duursma, Remko A., Barton, Craig V. M., Maier, Chelsea, Boer, Matthias M., Isaac, Peter, Tissue, David T., Resco de Dios, Víctor, and Pendall, Elise
- Subjects
lcsh:Geology ,lcsh:QH501-531 ,lcsh:QH540-549.5 ,lcsh:QE1-996.5 ,lcsh:Life ,lcsh:Ecology - Abstract
Predicting the seasonal dynamics of ecosystem carbon fluxes is challenging in broadleaved evergreen forests because of their moderate climates and subtle changes in canopy phenology. We assessed the climatic and biotic drivers of the seasonality of net ecosystem–atmosphere CO2 exchange (NEE) of a eucalyptus-dominated forest near Sydney, Australia, using the eddy covariance method. The climate is characterised by a mean annual precipitation of 800 mm and a mean annual temperature of 18 ∘C, hot summers and mild winters, with highly variable precipitation. In the 4-year study, the ecosystem was a sink each year (−225 g C m−2 yr−1 on average, with a standard deviation of 108 g C m−2 yr−1); inter-annual variations were not related to meteorological conditions. Daily net C uptake was always detected during the cooler, drier winter months (June through August), while net C loss occurred during the warmer, wetter summer months (December through February). Gross primary productivity (GPP) seasonality was low, despite longer days with higher light intensity in summer, because vapour pressure deficit (D) and air temperature (Ta) restricted surface conductance during summer while winter temperatures were still high enough to support photosynthesis. Maximum GPP during ideal environmental conditions was significantly correlated with remotely sensed enhanced vegetation index (EVI; r2 = 0.46) and with canopy leaf area index (LAI; r2 = 0.29), which increased rapidly after mid-summer rainfall events. Ecosystem respiration (ER) was highest during summer in wet soils and lowest during winter months. ER had larger seasonal amplitude compared to GPP, and therefore drove the seasonal variation of NEE. Because summer carbon uptake may become increasingly limited by atmospheric demand and high temperature, and because ecosystem respiration could be enhanced by rising temperatures, our results suggest the potential for large-scale seasonal shifts in NEE in sclerophyll vegetation under climate change.
- Published
- 2018
46. Ecotrons: Powerful and versatile ecosystem analysers for ecology, agronomy and environmental science
- Author
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Roy, Jacques, primary, Rineau, François, additional, De Boeck, Hans J., additional, Nijs, Ivan, additional, Pütz, Thomas, additional, Abiven, Samuel, additional, Arnone, John A., additional, Barton, Craig V. M., additional, Beenaerts, Natalie, additional, Brüggemann, Nicolas, additional, Dainese, Matteo, additional, Domisch, Timo, additional, Eisenhauer, Nico, additional, Garré, Sarah, additional, Gebler, Alban, additional, Ghirardo, Andrea, additional, Jasoni, Richard L., additional, Kowalchuk, George, additional, Landais, Damien, additional, Larsen, Stuart H., additional, Leemans, Vincent, additional, Le Galliard, Jean‐François, additional, Longdoz, Bernard, additional, Massol, Florent, additional, Mikkelsen, Teis N., additional, Niedrist, Georg, additional, Piel, Clément, additional, Ravel, Olivier, additional, Sauze, Joana, additional, Schmidt, Anja, additional, Schnitzler, Jörg‐Peter, additional, Teixeira, Leonardo H., additional, Tjoelker, Mark G., additional, Weisser, Wolfgang W., additional, Winkler, Barbro, additional, and Milcu, Alexandru, additional
- Published
- 2021
- Full Text
- View/download PDF
47. Pastures and Climate Extremes: Impacts of cool season warming and drought on the productivity of key pasture species in a field experiment
- Author
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Churchill, Amber C., primary, Zhang, Haiyang, additional, Fuller, Kathryn J., additional, Amiji, Burhan, additional, Anderson, Ian C., additional, Barton, Craig V. M., additional, Carrillo, Yolima, additional, Catunda, Karen L. M., additional, Chandregowda, Manjunatha H., additional, Igwenagu, Chioma, additional, Jacob, Vinod, additional, Kim, Gil Won, additional, Macdonald, Catriona A., additional, Medlyn, Belinda E., additional, Moore, Ben D., additional, Pendall, Elise, additional, Plett, Jonathan M., additional, Post, Alison K., additional, Powell, Jeff R., additional, Tissue, David T., additional, Tjoelker, Mark G., additional, and Power, Sally A., additional
- Published
- 2020
- Full Text
- View/download PDF
48. Elevated CO2 alters the temperature sensitivity of stem CO2 efflux in a mature eucalypt woodland
- Author
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David S. Ellsworth, Nam Jin Noh, Kristine Y. Crous, Jinquan Li, Mark G. Tjoelker, Craig V. M. Barton, Elise Pendall, and Roberto L. Salomón
- Subjects
Maintenance respiration ,Carbon dioxide in Earth's atmosphere ,Q10 ,Growing season ,Plant Science ,Seasonality ,Biology ,medicine.disease ,Eucalyptus ,Animal science ,Respiration ,medicine ,Agronomy and Crop Science ,Water content ,Ecology, Evolution, Behavior and Systematics - Abstract
The CO2 efflux from tree stem surfaces to atmosphere (RS) is an important component in the carbon (C) balance of forest ecosystems. Rising atmospheric carbon dioxide concentrations [CO2] are expected to stimulate RS, because of greater C assimilation and carbohydrate supply to stems under rising [CO2]. Growth respiration (Rg) and maintenance respiration (Rm) during the warm growing season may respond differently to rising [CO2] due to different metabolic demands. To test the effect of elevated [CO2] (eCO2, ambient +150 ppm) on RS, we examined RS in mature Eucalyptus trees on a monthly basis for an entire year during the seventh year of exposure to eCO2. RS varied seasonally and mirrored seasonal variation in temperature. While RS was not significantly increased under eCO2 compared to ambient CO2 (aCO2), its temperature sensitivity was significantly decreased (Q10 of 1.92 for aCO2 and 1.56 for eCO2). The estimated annual Rg accounted for approximately 7–8% of annual total RS, 419 ± 103 g C m−2 yr-1, indicating that Rm contributes substantially to total RS in this mature woodland. Monthly mean RS was correlated with monthly mean soil temperature, soil moisture and monthly stem growth rate in this dry year, but soil moisture levels may have been insufficient to observe the impacts of eCO2 on stem growth in this droughted and phosphorous limited site. Our results highlight that eCO2 tends to increase Rm at low temperatures during the non-growing season, thus decreasing the temperature sensitivity of RS, despite a neutral effect of eCO2 on RS rates on a yearly basis.
- Published
- 2021
49. Tapping into the physiological responses to mistletoe infection during heat and drought stress.
- Author
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Griebel, Anne, Peters, Jennifer M R, Metzen, Daniel, Maier, Chelsea, Barton, Craig V M, Speckman, Heather N, Boer, Matthias M, Nolan, Rachael H, Choat, Brendan, and Pendall, Elise
- Subjects
EUCALYPTUS ,DROUGHTS ,MISTLETOES ,TEMPERATE forests ,SOIL moisture ,TREE mortality ,VAPOR pressure - Abstract
Mistletoes are important co-contributors to tree mortality globally, particularly during droughts. In Australia, mistletoe distributions are expanding in temperate woodlands, while their hosts have experienced unprecedented heat and drought stress in recent years. We investigated whether the excessive water use of mistletoes increased the probability of xylem emboli in a mature woodland during the recent record drought that was compounded by multiple heatwaves. We continuously recorded transpiration (|$T_{SLA}$|) of infected and uninfected branches from two eucalypt species over two summers, monitored stem and leaf water potentials (|$\Psi $|) and used hydraulic vulnerability curves to estimate percent loss in conductivity (PLC) for each species. Variations in weather (vapor pressure deficit, photosynthetically active radiation, soil water content), host species and % mistletoe foliage explained 78% of hourly |$T_{SLA}$|. While mistletoe acted as an uncontrollable sink for water in the host even during typical summer days, daily |$T_{SLA}$| increased up to 4-fold in infected branches on hot days, highlighting the previously overlooked importance of temperature stress in amplifying water loss in mistletoes. The increased water use of mistletoes resulted in significantly decreased host |$\Psi _{\rm{leaf}}$| and |$\Psi _{\rm{trunk}}$|. It further translated to an estimated increase of up to 11% PLC for infected hosts, confirming greater hydraulic dysfunction of infected trees that place them at higher risk of hydraulic failure. However, uninfected branches of Eucalyptus fibrosa F.Muell. had much tighter controls on water loss than uninfected branches of Eucalyptus moluccana Roxb. which shifted the risk of hydraulic failure towards an increased risk of carbon starvation for E. fibrosa. The contrasting mechanistic responses to heat and drought stress between both co-occurring species demonstrates the complexity of host–parasite interactions and highlights the challenge in predicting species-specific responses to biotic agents in a warmer and drier climate. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
50. No evidence of homeostatic regulation of leaf temperature in Eucalyptus parramattensis trees: integration of CO 2 flux and oxygen isotope methodologies
- Author
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Drake, John E., primary, Harwood, Richard, additional, Vårhammar, Angelica, additional, Barbour, Margaret M., additional, Reich, Peter B., additional, Barton, Craig V. M., additional, and Tjoelker, Mark G., additional
- Published
- 2020
- Full Text
- View/download PDF
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