Plant measurements on African tropical Maesopsis eminii seedlings contradict pioneering water use behaviour

Epila, J; Maes, WH; Verbeeck, H; Van Camp, J; Okullo, JBL; Steppe, K

Plant measurements on African tropical Maesopsis eminii seedlings contradict pioneering water use behaviour

Epila, J Maes, WH

Verbeeck, H Van Camp, J Okullo, JBL Steppe, K

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Publication Type:: Journal Article
Citation:: Environmental and Experimental Botany, 2017, 135 pp. 27 - 37
Issue Date:: 2017-03-01

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Field	Value	Language
dc.contributor.author	Epila, J	en_US
dc.contributor.author	Maes, WH https://orcid.org/0000-0002-1592-9299	en_US
dc.contributor.author	Verbeeck, H	en_US
dc.contributor.author	Van Camp, J	en_US
dc.contributor.author	Okullo, JBL	en_US
dc.contributor.author	Steppe, K	en_US
dc.date.issued	2017-03-01	en_US
dc.identifier.citation	Environmental and Experimental Botany, 2017, 135 pp. 27 - 37	en_US
dc.identifier.issn	0098-8472	en_US
dc.identifier.uri	http://hdl.handle.net/10453/125804
dc.description.abstract	© 2016 Elsevier B.V. With increased drought events affecting forests globally, little is known about their future impact on Africa's forests. In particular, we need to gain a better understanding of how key African forest species will respond to drought stress. In this study, we investigated functional traits and physiological responses to drought of the light-demanding pioneer species Maesopsis eminii Engl. The study involved an experiment on potted M. eminii seedlings with three different drought treatments in which sap flow (SF), stem diameter variation (SDV) and stomatal conductance (gs) were measured. Whereas low gs rates (39 ± 30 mmol m−2 s−1) and pronounced SF-VPD (vapour pressure deficit) and gs-VPD hysteresis loops during well-watered conditions indicated conservative stomatal control on water loss, nocturnal sap flow implied M. eminii is not able to completely block transpiration. At the onset of drought, the pioneer seedlings retained high stem diameter growth despite highly reduced soil moisture (>−0.95 ± 0.03 MPa) and SF rates, indicating that growth was prioritised. Contribution of stored stem water to daily water use was limited both during drought and control conditions, which was confirmed by the absence of time lags between photosynthetic active radiation (PAR)-SDV, PAR-SF and SDV-SF in all treatments. Below a soil water potential of −0.95 ± 0.03 MPa, leaves were gradually shed, but diurnal and nocturnal SF did not turn zero, and absolute stem diameter kept decreasing for the entire experimental period (115 days), portraying that M. eminii seedlings can survive only limited drought periods. In sum, this study demonstrated that species-specific traits, as opposed to species ecological strategy, govern drought performance. For M. eminii, its leaf traits proved pivotal to its drought performance.	en_US
dc.relation.ispartof	Environmental and Experimental Botany	en_US
dc.relation.isbasedon	10.1016/j.envexpbot.2016.12.006	en_US
dc.subject.classification	Plant Biology & Botany	en_US
dc.title	Plant measurements on African tropical Maesopsis eminii seedlings contradict pioneering water use behaviour	en_US
dc.type	Journal Article
utslib.citation.volume	135	en_US
utslib.for	0501 Ecological Applications	en_US
utslib.for	0601 Biochemistry and Cell Biology	en_US
utslib.for	0701 Agriculture, Land and Farm Management	en_US
utslib.for	05 Environmental Sciences	en_US
utslib.for	06 Biological Sciences	en_US
utslib.for	07 Agricultural and Veterinary 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.publication-status	Published	en_US
pubs.volume	135	en_US

Abstract:

© 2016 Elsevier B.V. With increased drought events affecting forests globally, little is known about their future impact on Africa's forests. In particular, we need to gain a better understanding of how key African forest species will respond to drought stress. In this study, we investigated functional traits and physiological responses to drought of the light-demanding pioneer species Maesopsis eminii Engl. The study involved an experiment on potted M. eminii seedlings with three different drought treatments in which sap flow (SF), stem diameter variation (SDV) and stomatal conductance (gs) were measured. Whereas low gs rates (39 ± 30 mmol m−2 s−1) and pronounced SF-VPD (vapour pressure deficit) and gs-VPD hysteresis loops during well-watered conditions indicated conservative stomatal control on water loss, nocturnal sap flow implied M. eminii is not able to completely block transpiration. At the onset of drought, the pioneer seedlings retained high stem diameter growth despite highly reduced soil moisture (>−0.95 ± 0.03 MPa) and SF rates, indicating that growth was prioritised. Contribution of stored stem water to daily water use was limited both during drought and control conditions, which was confirmed by the absence of time lags between photosynthetic active radiation (PAR)-SDV, PAR-SF and SDV-SF in all treatments. Below a soil water potential of −0.95 ± 0.03 MPa, leaves were gradually shed, but diurnal and nocturnal SF did not turn zero, and absolute stem diameter kept decreasing for the entire experimental period (115 days), portraying that M. eminii seedlings can survive only limited drought periods. In sum, this study demonstrated that species-specific traits, as opposed to species ecological strategy, govern drought performance. For M. eminii, its leaf traits proved pivotal to its drought performance.

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http://hdl.handle.net/10453/125804