Trees tolerate an extreme heatwave via sustained transpirational cooling and increased leaf thermal tolerance

Drake, JE; Tjoelker, MG; Vårhammar, A; Medlyn, B; Reich, PB; Leigh, A; Pfautsch, S; Blackman, CJ; López, R; Aspinwall, MJ; Crous, KY; Duursma, RA; Kumarathunge, D; De Kauwe, MG; Jiang, M; Nicotra, AB; Tissue, DT; Choat, B; Atkin, OK; Barton, CVM

Trees tolerate an extreme heatwave via sustained transpirational cooling and increased leaf thermal tolerance

Drake, JE Tjoelker, MG Vårhammar, A Medlyn, B Reich, PB Leigh, A

Pfautsch, S Blackman, CJ López, R Aspinwall, MJ Crous, KY Duursma, RA Kumarathunge, D De Kauwe, MG Jiang, M Nicotra, AB Tissue, DT Choat, B Atkin, OK Barton, CVM

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Publication Type:: Journal Article
Citation:: Global Change Biology, 2018, 24 (6), pp. 2390 - 2402
Issue Date:: 2018-06-01

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Field	Value	Language
dc.contributor.author	Drake, JE	en_US
dc.contributor.author	Tjoelker, MG	en_US
dc.contributor.author	Vårhammar, A	en_US
dc.contributor.author	Medlyn, B	en_US
dc.contributor.author	Reich, PB	en_US
dc.contributor.author	Leigh, A https://orcid.org/0000-0003-3568-2606	en_US
dc.contributor.author	Pfautsch, S	en_US
dc.contributor.author	Blackman, CJ	en_US
dc.contributor.author	López, R	en_US
dc.contributor.author	Aspinwall, MJ	en_US
dc.contributor.author	Crous, KY	en_US
dc.contributor.author	Duursma, RA	en_US
dc.contributor.author	Kumarathunge, D	en_US
dc.contributor.author	De Kauwe, MG	en_US
dc.contributor.author	Jiang, M	en_US
dc.contributor.author	Nicotra, AB	en_US
dc.contributor.author	Tissue, DT	en_US
dc.contributor.author	Choat, B	en_US
dc.contributor.author	Atkin, OK	en_US
dc.contributor.author	Barton, CVM	en_US
dc.date.available	2017-11-21	en_US
dc.date.issued	2018-06-01	en_US
dc.identifier.citation	Global Change Biology, 2018, 24 (6), pp. 2390 - 2402	en_US
dc.identifier.issn	1354-1013	en_US
dc.identifier.uri	http://hdl.handle.net/10453/122045
dc.description.abstract	© 2018 John Wiley & Sons Ltd 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 CO2 and H2O, leaf temperatures, leaf thermal tolerance, and leaf and branch hydraulic status. The heatwave reduced midday canopy photosynthesis to near zero but transpiration persisted, maintaining canopy cooling. A standard photosynthetic model was unable to capture the observed decoupling between photosynthesis and transpiration at high temperatures, suggesting that climate models may underestimate a moderating feedback of vegetation on heatwave intensity. The heatwave also triggered a rapid increase in leaf thermal tolerance, such that leaf temperatures observed during the heatwave were maintained within the thermal limits of leaf function. All responses were equivalent for trees with a prior history of ambient and warmed (+3°C) temperatures, indicating that climate warming conferred no added tolerance of heatwaves expected in the future. This coordinated physiological response utilizing latent cooling and adjustment of thermal thresholds has implications for tree tolerance of future climate extremes as well as model predictions of future heatwave intensity at landscape and global scales.	en_US
dc.relation.ispartof	Global Change Biology	en_US
dc.relation.isbasedon	10.1111/gcb.14037	en_US
dc.subject.classification	Ecology	en_US
dc.subject.mesh	Eucalyptus	en_US
dc.subject.mesh	Plant Leaves	en_US
dc.subject.mesh	Trees	en_US
dc.subject.mesh	Plant Transpiration	en_US
dc.subject.mesh	Hot Temperature	en_US
dc.subject.mesh	Climate Change	en_US
dc.subject.mesh	Forests	en_US
dc.title	Trees tolerate an extreme heatwave via sustained transpirational cooling and increased leaf thermal tolerance	en_US
dc.type	Journal Article
utslib.citation.volume	6	en_US
utslib.citation.volume	24	en_US
utslib.for	0607 Plant Biology	en_US
utslib.for	050101 Ecological Impacts of Climate Change	en_US
utslib.for	05 Environmental Sciences	en_US
utslib.for	06 Biological Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
utslib.copyright.status	closed_access
pubs.issue	6	en_US
pubs.publication-status	Published	en_US
pubs.volume	24	en_US

Abstract:

© 2018 John Wiley & Sons Ltd 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 CO2 and H2O, leaf temperatures, leaf thermal tolerance, and leaf and branch hydraulic status. The heatwave reduced midday canopy photosynthesis to near zero but transpiration persisted, maintaining canopy cooling. A standard photosynthetic model was unable to capture the observed decoupling between photosynthesis and transpiration at high temperatures, suggesting that climate models may underestimate a moderating feedback of vegetation on heatwave intensity. The heatwave also triggered a rapid increase in leaf thermal tolerance, such that leaf temperatures observed during the heatwave were maintained within the thermal limits of leaf function. All responses were equivalent for trees with a prior history of ambient and warmed (+3°C) temperatures, indicating that climate warming conferred no added tolerance of heatwaves expected in the future. This coordinated physiological response utilizing latent cooling and adjustment of thermal thresholds has implications for tree tolerance of future climate extremes as well as model predictions of future heatwave intensity at landscape and global scales.

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http://hdl.handle.net/10453/122045