Towards physiologically meaningful water-use efficiency estimates from eddy covariance data

© 2017 John Wiley & Sons Ltd.

Bibliographische Detailangaben
Veröffentlicht in:Global change biology. - 1999. - 24(2018), 2 vom: 15. Feb., Seite 694-710
1. Verfasser: Knauer, Jürgen (VerfasserIn)
Weitere Verfasser: Zaehle, Sönke, Medlyn, Belinda E, Reichstein, Markus, Williams, Christopher A, Migliavacca, Mirco, De Kauwe, Martin G, Werner, Christiane, Keitel, Claudia, Kolari, Pasi, Limousin, Jean-Marc, Linderson, Maj-Lena
Format: Online-Aufsatz
Sprache:English
Veröffentlicht: 2018
Zugriff auf das übergeordnete Werk:Global change biology
Schlagworte:Journal Article Research Support, Non-U.S. Gov't Penman-Monteith equation aerodynamic conductance canopy gradients eddy covariance energy imbalance intrinsic water-use efficiency slope parameter surface conductance mehr... Water 059QF0KO0R Carbon Dioxide 142M471B3J Carbon 7440-44-0
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100 1 |a Knauer, Jürgen  |e verfasserin  |4 aut 
245 1 0 |a Towards physiologically meaningful water-use efficiency estimates from eddy covariance data 
264 1 |c 2018 
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500 |a Date Completed 23.10.2018 
500 |a Date Revised 09.04.2021 
500 |a published: Print-Electronic 
500 |a ErratumIn: Glob Chang Biol. 2021 May;27(9):1991. - PMID 33834574 
500 |a Citation Status MEDLINE 
520 |a © 2017 John Wiley & Sons Ltd. 
520 |a Intrinsic water-use efficiency (iWUE) characterizes the physiological control on the simultaneous exchange of water and carbon dioxide in terrestrial ecosystems. Knowledge of iWUE is commonly gained from leaf-level gas exchange measurements, which are inevitably restricted in their spatial and temporal coverage. Flux measurements based on the eddy covariance (EC) technique can overcome these limitations, as they provide continuous and long-term records of carbon and water fluxes at the ecosystem scale. However, vegetation gas exchange parameters derived from EC data are subject to scale-dependent and method-specific uncertainties that compromise their ecophysiological interpretation as well as their comparability among ecosystems and across spatial scales. Here, we use estimates of canopy conductance and gross primary productivity (GPP) derived from EC data to calculate a measure of iWUE (G1 , "stomatal slope") at the ecosystem level at six sites comprising tropical, Mediterranean, temperate, and boreal forests. We assess the following six mechanisms potentially causing discrepancies between leaf and ecosystem-level estimates of G1 : (i) non-transpirational water fluxes; (ii) aerodynamic conductance; (iii) meteorological deviations between measurement height and canopy surface; (iv) energy balance non-closure; (v) uncertainties in net ecosystem exchange partitioning; and (vi) physiological within-canopy gradients. Our results demonstrate that an unclosed energy balance caused the largest uncertainties, in particular if it was associated with erroneous latent heat flux estimates. The effect of aerodynamic conductance on G1 was sufficiently captured with a simple representation. G1 was found to be less sensitive to meteorological deviations between canopy surface and measurement height and, given that data are appropriately filtered, to non-transpirational water fluxes. Uncertainties in the derived GPP and physiological within-canopy gradients and their implications for parameter estimates at leaf and ecosystem level are discussed. Our results highlight the importance of adequately considering the sources of uncertainty outlined here when EC-derived water-use efficiency is interpreted in an ecophysiological context 
650 4 |a Journal Article 
650 4 |a Research Support, Non-U.S. Gov't 
650 4 |a Penman-Monteith equation 
650 4 |a aerodynamic conductance 
650 4 |a canopy gradients 
650 4 |a eddy covariance 
650 4 |a energy imbalance 
650 4 |a intrinsic water-use efficiency 
650 4 |a slope parameter 
650 4 |a surface conductance 
650 7 |a Water  |2 NLM 
650 7 |a 059QF0KO0R  |2 NLM 
650 7 |a Carbon Dioxide  |2 NLM 
650 7 |a 142M471B3J  |2 NLM 
650 7 |a Carbon  |2 NLM 
650 7 |a 7440-44-0  |2 NLM 
700 1 |a Zaehle, Sönke  |e verfasserin  |4 aut 
700 1 |a Medlyn, Belinda E  |e verfasserin  |4 aut 
700 1 |a Reichstein, Markus  |e verfasserin  |4 aut 
700 1 |a Williams, Christopher A  |e verfasserin  |4 aut 
700 1 |a Migliavacca, Mirco  |e verfasserin  |4 aut 
700 1 |a De Kauwe, Martin G  |e verfasserin  |4 aut 
700 1 |a Werner, Christiane  |e verfasserin  |4 aut 
700 1 |a Keitel, Claudia  |e verfasserin  |4 aut 
700 1 |a Kolari, Pasi  |e verfasserin  |4 aut 
700 1 |a Limousin, Jean-Marc  |e verfasserin  |4 aut 
700 1 |a Linderson, Maj-Lena  |e verfasserin  |4 aut 
773 0 8 |i Enthalten in  |t Global change biology  |d 1999  |g 24(2018), 2 vom: 15. Feb., Seite 694-710  |w (DE-627)NLM098239996  |x 1365-2486  |7 nnns 
773 1 8 |g volume:24  |g year:2018  |g number:2  |g day:15  |g month:02  |g pages:694-710 
856 4 0 |u http://dx.doi.org/10.1111/gcb.13893  |3 Volltext 
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