globalchange  > 影响、适应和脆弱性
DOI: 10.1111/gcb.13893
Scopus记录号: 2-s2.0-85041375135
论文题名:
Towards physiologically meaningful water-use efficiency estimates from eddy covariance data
作者: Knauer J.; Zaehle S.; Medlyn B.E.; Reichstein M.; Williams C.A.; Migliavacca M.; De Kauwe M.G.; Werner C.; Keitel C.; Kolari P.; Limousin J.-M.; Linderson M.-L.
刊名: Global Change Biology
ISSN: 13541013
出版年: 2018
卷: 24, 期:2
起始页码: 694
结束页码: 710
语种: 英语
英文关键词: aerodynamic conductance ; canopy gradients ; eddy covariance ; energy imbalance ; intrinsic water-use efficiency ; Penman–Monteith equation ; slope parameter ; surface conductance
Scopus关键词: aerodynamics ; canopy architecture ; carbon cycle ; ecophysiology ; eddy covariance ; energy balance ; net ecosystem exchange ; physiological response ; primary production ; terrestrial ecosystem ; uncertainty analysis ; water use efficiency
英文摘要: 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. © 2017 John Wiley & Sons Ltd
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110516
Appears in Collections:影响、适应和脆弱性
气候变化事实与影响

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作者单位: Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, Jena, Germany; International Max Planck Research School for Global Biogeochemical Cycles (IMPRS-gBGC), Jena, Germany; Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia; Michael-Stifel-Center Jena for Data-Driven and Simulation Science, Jena, Germany; Graduate School of Geography, Clark University, Worcester, MA, United States; Department of Biological Science, Macquarie University, North Ryde, NSW, Australia; ARC Centre of Excellence for Climate Extremes, University of New South Wales, Sydney, NSW, Australia; Department of Ecosystem Physiology, University of Freiburg, Freiburg, Germany; School of Life and Environmental Science, University of Sydney, Brownlow Hill, NSW, Australia; Department of Physics, University of Helsinki, Helsinki, Finland; Centre d'Ecologie Fonctionnelle et Evolutive, Université de Montpellier, Montpellier, France; Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden

Recommended Citation:
Knauer J.,Zaehle S.,Medlyn B.E.,et al. Towards physiologically meaningful water-use efficiency estimates from eddy covariance data[J]. Global Change Biology,2018-01-01,24(2)
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