Spatial and temporal variations in plant water-use efficiency inferred from tree-ring, eddy covariance and atmospheric observations

Dekker, Stefan C.; Groenendijk, Margriet; Booth, Ben B.B.; Huntingford, Chris; Cox, Peter M.. 2016 Spatial and temporal variations in plant water-use efficiency inferred from tree-ring, eddy covariance and atmospheric observations. Earth System Dynamics, 7 (2). 525-533.

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Plant water-use efficiency (WUE), which is the ratio of the uptake of carbon dioxide through photosynthesis to the loss of water through transpiration, is a very useful metric of the functioning of the land biosphere. WUE is expected to increase with atmospheric CO2, but to decline with increasing atmospheric evaporative demand – which can arisefrom increases in near-surface temperature or decreases in relative humidity.We have used Δ13C measurements from tree rings, along witheddy covariance measurements from Fluxnet sites, to estimate thesensitivities of WUE to changes in CO2 and atmospheric humidity deficit.This enables us to reconstruct fractional changes in WUE, based on changes inatmospheric climate and CO2, for the entire period of the instrumental global climate record. We estimate that overall WUE increased from 1900 to2010 by 48 ± 22 %, which is more than double that simulated by thelatest Earth System Models. This long-term trend is largely driven byincreases in CO2, but significant inter-annual variability and regional differences are evident due to variations in temperature and relativehumidity. There are several highly populated regions, such as western Europeand East Asia, where the rate of increase of WUE has declined sharply in thelast 2 decades. Our data-based analysis indicates increases in WUE thattypically exceed those simulated by Earth System Models – implying thatthese models are either underestimating increases in photosynthesis orunderestimating reductions in transpiration.

Item Type: Publication - Article
Digital Object Identifier (DOI):
UKCEH and CEH Sections/Science Areas: Reynard
ISSN: 2190-4979
Additional Information. Not used in RCUK Gateway to Research.: Open Access paper - full text available via Official URL link.
NORA Subject Terms: Botany
Date made live: 08 Mar 2017 12:34 +0 (UTC)

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