Quantifying soil moisture impacts on light use efficiency across biomes.

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Title: Quantifying soil moisture impacts on light use efficiency across biomes.
Author(s): Stocker, BD
Zscheischler, J
Keenan, TF
Prentice, IC
Peñuelas, J
Seneviratne, SI
Item Type: Journal Article
Abstract: Terrestrial primary productivity and carbon cycle impacts of droughts are commonly quantified using vapour pressure deficit (VPD) data and remotely sensed greenness, without accounting for soil moisture. However, soil moisture limitation is known to strongly affect plant physiology. Here, we investigate light use efficiency, the ratio of gross primary productivity (GPP) to absorbed light. We derive its fractional reduction due to soil moisture (fLUE), separated from VPD and greenness changes, using artificial neural networks trained on eddy covariance data, multiple soil moisture datasets and remotely sensed greenness. This reveals substantial impacts of soil moisture alone that reduce GPP by up to 40% at sites located in sub-humid, semi-arid or arid regions. For sites in relatively moist climates, we find, paradoxically, a muted fLUE response to drying soil, but reduced fLUE under wet conditions. fLUE identifies substantial drought impacts that are not captured when relying solely on VPD and greenness changes and, when seasonally recurring, are missed by traditional, anomaly-based drought indices. Counter to common assumptions, fLUE reductions are largest in drought-deciduous vegetation, including grasslands. Our results highlight the necessity to account for soil moisture limitation in terrestrial primary productivity data products, especially for drought-related assessments.
Publication Date: 31-Mar-2018
Date of Acceptance: 10-Feb-2018
URI: http://hdl.handle.net/10044/1/59029
DOI: https://dx.doi.org/10.1111/nph.15123
ISSN: 0028-646X
Publisher: Wiley
Start Page: 1430
End Page: 1449
Journal / Book Title: New Phytologist
Volume: 218
Issue: 4
Copyright Statement: © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords: drought impacts
eddy covariance
gross primary productivity (GPP)
light use efficiency
photosynthesis
soil moisture
standardized precipitation index
vapour pressure deficit (VPD)
drought impacts
eddy covariance
gross primary productivity (GPP)
light use efficiency
photosynthesis
soil moisture
standardized precipitation index
vapour pressure deficit (VPD)
06 Biological Sciences
07 Agricultural And Veterinary Sciences
Plant Biology & Botany
Publication Status: Published
Conference Place: England
Appears in Collections:Centre for Environmental Policy
Faculty of Natural Sciences



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