Interactive effects of elevated CO <inf>2</inf> and drought on nocturnal water fluxes in Eucalyptus saligna

Zeppel, MJB; Lewis, JD; Medlyn, B; Barton, CVM; Duursma, RA; Eamus, D; Adams, MA; Phillips, N; Ellsworth, DS; Forster, MA; Tissue, DT

Interactive effects of elevated CO <inf>2</inf> and drought on nocturnal water fluxes in Eucalyptus saligna

Zeppel, MJB

Lewis, JD Medlyn, B Barton, CVM Duursma, RA Eamus, D

Adams, MA Phillips, N Ellsworth, DS Forster, MA Tissue, DT

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Publication Type:: Journal Article
Citation:: Tree Physiology, 2011, 31 (9), pp. 932 - 944
Issue Date:: 2011-09-01

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Field	Value	Language
dc.contributor.author	Zeppel, MJB https://orcid.org/0000-0002-5510-0936	en_US
dc.contributor.author	Lewis, JD	en_US
dc.contributor.author	Medlyn, B	en_US
dc.contributor.author	Barton, CVM	en_US
dc.contributor.author	Duursma, RA	en_US
dc.contributor.author	Eamus, D https://orcid.org/0000-0003-2765-8040	en_US
dc.contributor.author	Adams, MA	en_US
dc.contributor.author	Phillips, N	en_US
dc.contributor.author	Ellsworth, DS	en_US
dc.contributor.author	Forster, MA	en_US
dc.contributor.author	Tissue, DT	en_US
dc.date.issued	2011-09-01	en_US
dc.identifier.citation	Tree Physiology, 2011, 31 (9), pp. 932 - 944	en_US
dc.identifier.issn	0829-318X	en_US
dc.identifier.uri	http://hdl.handle.net/10453/18144
dc.description.abstract	Nocturnal water flux has been observed in trees under a variety of environmental conditions and can be a significant contributor to diel canopy water flux. Elevated atmospheric CO 2 (elevated [CO 2]) can have an important effect on day-time plant water fluxes, but it is not known whether it also affects nocturnal water fluxes. We examined the effects of elevated [CO 2] on nocturnal water flux of field-grown Eucalyptus saligna trees using sap flux through the tree stem expressed on a sapwood area (J s) and leaf area (E t) basis. After 19 months growth under well-watered conditions, drought was imposed by withholding water for 5 months in the summer, ending with a rain event that restored soil moisture. Reductions in J s and E t were observed during the severe drought period in the dry treatment under elevated [CO 2], but not during moderate- and post-drought periods. Elevated [CO 2] affected night-time sap flux density which included the stem recharge period, called 'total night flux' (19:00 to 05:00, J s,r), but not during the post-recharge period, which primarily consisted of canopy transpiration (23:00 to 05:00, J s,c). Elevated [CO 2] wet (EW) trees exhibited higher J s,r than ambient [CO 2] wet trees (AW) indicating greater water flux in elevated [CO 2] under well-watered conditions. However, under drought conditions, elevated [CO 2] dry (ED) trees exhibited significantly lower J s,r than ambient [CO 2] dry trees (AD), indicating less water flux during stem recharge under elevated [CO 2]. J s,c did not differ between ambient and elevated [CO 2]. Vapour pressure deficit (D) was clearly the major influence on night-time sap flux. D was positively correlated with J s,r and had its greatest impact on J s,r at high D in ambient [CO 2]. Our results suggest that elevated [CO 2] may reduce night-time water flux in E. saligna when soil water content is low and D is high. While elevated [CO 2] affected J s,r, it did not affect day-time water flux in wet soil, suggesting that the responses of J s,r to environmental factors cannot be directly inferred from day-time patterns. Changes in J s,r are likely to influence pre-dawn leaf water potential, and plant responses to water stress. Nocturnal fluxes are clearly important for predicting effects of climate change on forest physiology and hydrology. © 2011 The Author. Published by Oxford University Press. A ll rights reserved.	en_US
dc.relation.ispartof	Tree Physiology	en_US
dc.relation.isbasedon	10.1093/treephys/tpr024	en_US
dc.subject.classification	Plant Biology & Botany	en_US
dc.subject.mesh	Eucalyptus	en_US
dc.subject.mesh	Plant Leaves	en_US
dc.subject.mesh	Plant Stems	en_US
dc.subject.mesh	Plant Roots	en_US
dc.subject.mesh	Dehydration	en_US
dc.subject.mesh	Carbon Dioxide	en_US
dc.subject.mesh	Carbon	en_US
dc.subject.mesh	Water	en_US
dc.subject.mesh	Soil	en_US
dc.subject.mesh	Greenhouse Effect	en_US
dc.subject.mesh	Plant Transpiration	en_US
dc.subject.mesh	Circadian Rhythm	en_US
dc.subject.mesh	Western Australia	en_US
dc.subject.mesh	Plant Stomata	en_US
dc.title	Interactive effects of elevated CO <inf>2</inf> and drought on nocturnal water fluxes in Eucalyptus saligna	en_US
dc.type	Journal Article
utslib.citation.volume	9	en_US
utslib.citation.volume	31	en_US
utslib.for	060705 Plant Physiology	en_US
utslib.for	0602 Ecology	en_US
utslib.for	0607 Plant Biology	en_US
utslib.for	0705 Forestry 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
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
utslib.copyright.status	open_access
pubs.issue	9	en_US
pubs.publication-status	Published	en_US
pubs.volume	31	en_US

Abstract:

Nocturnal water flux has been observed in trees under a variety of environmental conditions and can be a significant contributor to diel canopy water flux. Elevated atmospheric CO 2 (elevated [CO 2]) can have an important effect on day-time plant water fluxes, but it is not known whether it also affects nocturnal water fluxes. We examined the effects of elevated [CO 2] on nocturnal water flux of field-grown Eucalyptus saligna trees using sap flux through the tree stem expressed on a sapwood area (J s) and leaf area (E t) basis. After 19 months growth under well-watered conditions, drought was imposed by withholding water for 5 months in the summer, ending with a rain event that restored soil moisture. Reductions in J s and E t were observed during the severe drought period in the dry treatment under elevated [CO 2], but not during moderate- and post-drought periods. Elevated [CO 2] affected night-time sap flux density which included the stem recharge period, called 'total night flux' (19:00 to 05:00, J s,r), but not during the post-recharge period, which primarily consisted of canopy transpiration (23:00 to 05:00, J s,c). Elevated [CO 2] wet (EW) trees exhibited higher J s,r than ambient [CO 2] wet trees (AW) indicating greater water flux in elevated [CO 2] under well-watered conditions. However, under drought conditions, elevated [CO 2] dry (ED) trees exhibited significantly lower J s,r than ambient [CO 2] dry trees (AD), indicating less water flux during stem recharge under elevated [CO 2]. J s,c did not differ between ambient and elevated [CO 2]. Vapour pressure deficit (D) was clearly the major influence on night-time sap flux. D was positively correlated with J s,r and had its greatest impact on J s,r at high D in ambient [CO 2]. Our results suggest that elevated [CO 2] may reduce night-time water flux in E. saligna when soil water content is low and D is high. While elevated [CO 2] affected J s,r, it did not affect day-time water flux in wet soil, suggesting that the responses of J s,r to environmental factors cannot be directly inferred from day-time patterns. Changes in J s,r are likely to influence pre-dawn leaf water potential, and plant responses to water stress. Nocturnal fluxes are clearly important for predicting effects of climate change on forest physiology and hydrology. © 2011 The Author. Published by Oxford University Press. A ll rights reserved.

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http://hdl.handle.net/10453/18144