Atmospheric dryness reduces photosynthesis along a large range of soil water deficits

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Title: Atmospheric dryness reduces photosynthesis along a large range of soil water deficits
Authors: Fu, Z
Ciais, P
Prentice, IC
Gentine, P
Makowski, D
Bastos, A
Luo, X
Green, J
Stoy, P
Yang, H
Hajima, T
Item Type: Journal Article
Abstract: Both low soil water content (SWC) and high atmospheric dryness (vapor pressure deficit, VPD) can negatively affect terrestrial gross primary production (GPP). The sensitivity of GPP to soil versus atmospheric dryness is difficult to disentangle, however, because of their covariation. Using global eddy-covariance observations, here we show that a decrease in SWC is not universally associated with GPP reduction. GPP increases in response to decreasing SWC when SWC is high and decreases only when SWC is below a threshold. By contrast, the sensitivity of GPP to an increase of VPD is always negative across the full SWC range. We further find canopy conductance decreases with increasing VPD (irrespective of SWC), and with decreasing SWC on drier soils. Maximum photosynthetic assimilation rate has negative sensitivity to VPD, and a positive sensitivity to decreasing SWC when SWC is high. Earth System Models underestimate the negative effect of VPD and the positive effect of SWC on GPP such that they should underestimate the GPP reduction due to increasing VPD in future climates.
Issue Date: 21-Feb-2022
Date of Acceptance: 28-Jan-2022
DOI: 10.1038/s41467-022-28652-7
ISSN: 2041-1723
Publisher: Nature Research
Journal / Book Title: Nature Communications
Volume: 13
Copyright Statement: © The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit
Sponsor/Funder: AXA Research Fund
Commission of the European Communities
Funder's Grant Number: AXA Chair Programme in Biosphere and Climate Impacts
Publication Status: Published
Article Number: ARTN 989
Appears in Collections:Grantham Institute for Climate Change

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