Carbon and water fluxes in an arid-zone acacia savanna woodland: An analyses of seasonal patterns and responses to rainfall events

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Show simple item record Eamus, D Cleverly, J Boulain, N Grant, N Faux, R Villalobos-Vega, R 2014-04-27T18:06:04Z 2013-12-15
dc.identifier.citation Agricultural and Forest Meteorology, 2013, 182-183 pp. 225 - 238
dc.identifier.issn 0168-1923
dc.identifier.other C1 en_US
dc.description.abstract The study of landscape gas exchange in arid and semi-arid regions is less common than those of more mesic environments, despite their large geographical extent, their importance to regional climate, their socioeconomic values and the carbon and water balances of such regions. In this study we used eddy covariance measurements to examine net ecosystem exchange and water fluxes of a landscape dominated by a N-fixing tree (Acacia aneura; Mulga) as a function of soil moisture content, vapour pressure deficit, leaf area index and pulses of rain. Seasonal budgets of carbon and water, ecosystem-scale water-use-efficiency (the ratio of net ecosystem exchange to evapotranspiration) and inherent water-use-efficiency (ecosystem water-use-efficiency. ×. vapour pressure deficit) were also examined. Across the 12 month study, the landscape was a net sink for carbon, despite prolonged periods of zero rain.Changes in both net ecosystem exchange and evapotranspiration were tightly coupled to changes in the moisture content of the upper (10. cm) soil profile, but not the deeper profile and both responded rapidly to changes in soil moisture content. As vapour pressure deficit increased over the course of several consecutive days in the wet season there was no significant response of ecosystem water-use-efficiency. In contrast, in the dry season, as vapour pressure deficit increased ecosystem water-use-efficiency declined curvilinearly. However, in both wet and dry seasons, ecosystem water-use-efficiency declined with increasing soil moisture content. Daily inherent water-use-efficiency increased gradually following each rainfall event. As daily mean vapour pressure deficit increased between rain events, inherent water-use-efficiency increased in both the wet and dry seasons but with a steeper slope in the wet season. However, inherent water-use-efficiency decreased with increasing soil moisture in both seasons, and the slope of a semi-log plot of inherent water-use-efficiency versus soil moisture content decreased faster in the dry season than in the wet season. Similarly, the marginal carbon cost of water was smaller (0.3) in the wet than dry season (0.6). Variations in ecosystem leaf area index were correlated with the under storey component, which was highest in the wet season and lowest in the dry season. We therefore conclude that changes in under storey leaf area index were significant drivers of seasonal changes in canopy gas exchange. Mulga, despite maintaining leaf area index through the dry season in a semi-arid environment, supports little dry season evapotranspiration and relies, to a very large extent, on soil moisture in the upper soil profile rather than deeper stores of water. © 2013 Elsevier B.V.
dc.language eng
dc.relation.isbasedon 10.1016/j.agrformet.2013.04.020
dc.title Carbon and water fluxes in an arid-zone acacia savanna woodland: An analyses of seasonal patterns and responses to rainfall events
dc.type Journal Article
dc.parent Agricultural and Forest Meteorology
dc.journal.volume 182-183
dc.journal.number 3-4 en_US
dc.publocation Netherlands en_US
dc.identifier.startpage 225 en_US
dc.identifier.endpage 238 en_US SCI.Plant Functional Biology & Climate Change en_US
dc.conference Verified OK en_US
dc.for 0705 Forestry Sciences
dc.for 0607 Plant Biology
dc.personcode 000006
dc.personcode 108965
dc.personcode 108525
dc.personcode 111479
dc.personcode 114455
dc.personcode 109733
dc.percentage 50 en_US Forestry Sciences en_US
dc.classification.type FOR-08 en_US
dc.edition en_US
dc.custom en_US en_US
dc.location.activity en_US
dc.description.keywords Eddy covariance
dc.description.keywords Net ecosystem exchange
dc.description.keywords Optimisation of stomatal conductance
dc.description.keywords Rain pulses
dc.description.keywords Water-use-efficiency
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 2015-04-15 12:17:09.805752+10
pubs.consider-herdc true
utslib.collection.history Closed (ID: 3)
utslib.collection.history School of the Environment (ID: 344)

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