How do leaf and ecosystem measures of water-use efficiency compare?

The terrestrial carbon and water cycles are intimately linked: the carbon cycle is driven by photosynthesis, while the water balance is dominated by transpiration, and both fluxes are controlled by plant stomatal conductance. The ratio between these fluxes, the plant water-use efficiency (WUE), is a...

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Veröffentlicht in:	The New phytologist Jg. 216; H. 3; S. 758 - 770
Hauptverfasser:	Medlyn, Belinda E., De Kauwe, Martin G., Lin, Yan‐Shih, Knauer, Jürgen, Duursma, Remko A., Williams, Christopher A., Arneth, Almut, Clement, Rob, Isaac, Peter, Limousin, Jean‐Marc, Linderson, Maj‐Lena, Meir, Patrick, Martin‐StPaul, Nicolas, Wingate, Lisa
Format:	Journal Article
Sprache:	Englisch
Veröffentlicht:	England New Phytologist Trust 01.11.2017 Wiley Subscription Services, Inc Wiley Wiley-Blackwell
Schlagworte:	C3 plants C4 plants carbon Carbon cycle Conductance Covariance crops Data data collection Databases, Factual deciduous forests Ecosystem Ecosystems eddy covariance Fluxes Forests Gas exchange Grasslands Hydrologic cycle Isotopes leaf gas exchange Leaves Life Sciences Measurement methods Photosynthesis plant functional type (PFT) Plant Leaves - physiology Plant Transpiration Poaceae - physiology Resistance Stable isotopes Stomata Stomatal conductance Transpiration uncertainty Vegetal Biology Vortices Water Water balance Water use water use efficiency stable isotopes stomatal conductance plant functional type (PFT) leaf gas exchange eddy covariance water-use efficiency dynamique des écosystèmes réserve en eau de la plante bilan hydrique isotope stable covariance carbon cycle photosynthèse utilisation de l'eau conductance stomatique photosynthesis cycle du carbone Efficience d'utilisation de l'eau
ISSN:	0028-646X, 1469-8137, 1469-8137
Online-Zugang:	Volltext
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Zusammenfassung:	The terrestrial carbon and water cycles are intimately linked: the carbon cycle is driven by photosynthesis, while the water balance is dominated by transpiration, and both fluxes are controlled by plant stomatal conductance. The ratio between these fluxes, the plant water-use efficiency (WUE), is a useful indicator of vegetation function. WUE can be estimated using several techniques, including leaf gas exchange, stable isotope discrimination, and eddy covariance. Here we compare global compilations of data for each of these three techniques. We show that patterns of variation in WUE across plant functional types (PFTs) are not consistent among the three datasets. Key discrepancies include the following: leaf-scale data indicate differences between needleleaf and broadleaf forests, but ecosystem-scale data do not; leaf-scale data indicate differences between C3 and C4 species, whereas at ecosystem scale there is a difference between C3 and C4 crops but not grasslands; and isotope-based estimates of WUE are higher than estimates based on gas exchange for most PFTs. Our study quantifies the uncertainty associated with different methods of measuring WUE, indicates potential for bias when using WUE measures to parameterize or validate models, and indicates key research directions needed to reconcile alternative measures of WUE.
Bibliographie:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 content type line 23 USDOE
ISSN:	0028-646X 1469-8137 1469-8137
DOI:	10.1111/nph.14626