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

Medlyn, Belinda E; De Kauwe, Martin G.; Lin, Yan-Shih; Knauer, Jürgen; Duursma, Remko A.; Williams, Christopher A.; Arneth, Almut LU ; Clement, Rob; Isaac, Peter and Limousin, Jean-Marc, et al. (2017) In New Phytologist
Abstract

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... (More)

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.

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Contribution to journal
publication status
in press
subject
keywords
Eddy covariance, Leaf gas exchange, Plant functional type (PFT), Stable isotopes, Stomatal conductance, Water-use efficiency
in
New Phytologist
publisher
Wiley-Blackwell
external identifiers
  • scopus:85020134074
ISSN
0028-646X
DOI
10.1111/nph.14626
language
English
LU publication?
yes
id
cd5036c0-e6d4-4662-a771-865ef3e33589
date added to LUP
2017-06-29 16:12:07
date last changed
2017-06-29 19:52:00
@article{cd5036c0-e6d4-4662-a771-865ef3e33589,
  abstract     = {<p>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 C<sub>3</sub> and C<sub>4</sub> species, whereas at ecosystem scale there is a difference between C<sub>3</sub> and C<sub>4</sub> 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.</p>},
  author       = {Medlyn, Belinda E and De Kauwe, Martin G. and Lin, Yan-Shih and Knauer, Jürgen and Duursma, Remko A. and Williams, Christopher A. and Arneth, Almut and Clement, Rob and Isaac, Peter and Limousin, Jean-Marc and Linderson, Maj Lena and Meir, Patrick and Martin-Stpaul, Nicolas and Wingate, Lisa},
  issn         = {0028-646X},
  keyword      = {Eddy covariance,Leaf gas exchange,Plant functional type (PFT),Stable isotopes,Stomatal conductance,Water-use efficiency},
  language     = {eng},
  publisher    = {Wiley-Blackwell},
  series       = {New Phytologist},
  title        = {How do leaf and ecosystem measures of water-use efficiency compare?},
  url          = {http://dx.doi.org/10.1111/nph.14626},
  year         = {2017},
}