Effects of elevated atmospheric [CO 2] on instantaneous transpiration efficiency at leaf and canopy scales in Eucalyptus saligna

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dc.contributor.author Barton, CV
dc.contributor.author Duursma, RA
dc.contributor.author Medlyn, BE
dc.contributor.author Ellsworth, DS
dc.contributor.author Eamus, D
dc.contributor.author Tissue, DT
dc.contributor.author Adams, MA
dc.contributor.author Conroy, J
dc.contributor.author Crous, KY
dc.contributor.author Liberloo, M
dc.contributor.author Löw, M
dc.contributor.author Linder, S
dc.contributor.author Mcmurtrie, RE
dc.date.accessioned 2012-10-12T03:33:17Z
dc.date.issued 2012-02
dc.identifier.citation Global Change Biology, 2012, 18 (2), pp. 585 - 595
dc.identifier.issn 1354-1013
dc.identifier.other C5 en_US
dc.identifier.uri http://hdl.handle.net/10453/18094
dc.description.abstract Rising atmospheric concentrations of CO 2 (C a) can reduce stomatal conductance and transpiration rate in trees, but the magnitude of this effect varies considerably among experiments. The theory of optimal stomatal behaviour predicts that the ratio of photosynthesis to transpiration (instantaneous transpiration efficiency, ITE) should increase in proportion to C a. We hypothesized that plants regulate stomatal conductance optimally in response to rising C a. We tested this hypothesis with data from young Eucalyptus saligna Sm. trees grown in 12 climate-controlled whole-tree chambers for 2 years at ambient and elevated C a. Elevated C a was ambient + 240 ppm, 60% higher than ambient C a. Leaf-scale gas exchange was measured throughout the second year of the study and leaf-scale ITE increased by 60% under elevated C a, as predicted. Values of leaf-scale ITE depended strongly on vapour pressure deficit (D) in both CO 2 treatments. Whole-canopy CO 2 and H 2O fluxes were also monitored continuously for each chamber throughout the second year. There were small differences in D between C a treatments, which had important effects on values of canopy-scale ITE. However, when C a treatments were compared at the same D, canopy-scale ITE was consistently increased by 60%, again as predicted. Importantly, leaf and canopy-scale ITE were not significantly different, indicating that ITE was not scale-dependent. Observed changes in transpiration rate could be explained on the basis that ITE increased in proportion to C a. The effect of elevated C a on photosynthesis increased with rising D. At high D, C a had a large effect on photosynthesis and a small effect on transpiration rate. At low D, in contrast, there was a small effect of C a on photosynthesis, but a much larger effect on transpiration rate. If shown to be a general response, the proportionality of ITE with C a will allow us to predict the effects of C a on transpiration rate. © 2011 Blackwell Publishing Ltd.
dc.language eng
dc.relation.isbasedon 10.1111/j.1365-2486.2011.02526.x
dc.title Effects of elevated atmospheric [CO 2] on instantaneous transpiration efficiency at leaf and canopy scales in Eucalyptus saligna
dc.type Journal Article
dc.parent Global Change Biology
dc.journal.volume 2
dc.journal.volume 18
dc.journal.number en_US
dc.publocation UK en_US
dc.publocation Singapore
dc.identifier.startpage en_US
dc.identifier.endpage en_US
dc.cauo.name SCI.Faculty of Science en_US
dc.conference Verified OK en_US
dc.for 0502 Environmental Science and Management
dc.personcode 000006
dc.percentage 100 en_US
dc.classification.name Environmental Science and Management en_US
dc.classification.type FOR-08 en_US
dc.edition en_US
dc.edition 1
dc.custom en_US
dc.date.activity en_US
dc.location.activity en_US
dc.description.keywords Elevated carbon dioxide
dc.description.keywords Eucalyptus
dc.description.keywords Transpiration efficiency
dc.description.keywords Water-use efficiency
dc.description.keywords Whole-tree chambers
pubs.embargo.period Not known
pubs.organisational-group /University of Technology Sydney
pubs.organisational-group /University of Technology Sydney/Faculty of Science
utslib.copyright.status Closed Access
utslib.copyright.date 2015-04-15 12:17:09.805752+10
pubs.consider-herdc false
utslib.collection.history Closed (ID: 3)
utslib.collection.history School of the Environment (ID: 344)

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