FU, Zheng; CIAIS, Philippe; FELDMAN, Andrew; GENTINE, Pierre; MAKOWSKI, David; PRENTICE, I; STOY, Paul; BASTOS, Ana; J.-P., Wigneron

doi:10.1126/sciadv.abq7827

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FU, Zheng
Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] [LSCE]

CIAIS, Philippe
Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] [LSCE]

FELDMAN, Andrew
NASA Goddard Space Flight Center [GSFC]

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Science Advances. 2022, vol. 8, n° 44, p. eabq7827

American Association for the Advancement of Science (AAAS)

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Plant water stress occurs at the point when soil moisture (SM) limits transpiration, defining a critical SM threshold ( crit). Knowledge of the spatial distribution of  crit is crucial for future projections of climate and water resources. Here, we use global eddy covariance observations to quantify  crit and evaporative fraction (EF) regimes. Three canonical variables describe how EF is controlled by SM: the maximum EF (EF max),  crit , and slope (S) between EF and SM. We find systematic differences of these three variables across biomes. Variation in  crit , S, and EF max is mostly explained by soil texture, vapor pressure deficit, and precipitation, respectively, as well as vegetation structure. Dryland ecosystems tend to operate at low  crit and show adaptation to water deficits. The negative relationship between  crit and S indicates that dryland ecosystems minimize  crit through mechanisms of sustained SM extraction and transport by xylem. Our results further suggest an optimal adaptation of local EF-SM response that maximizes growing-season evapotranspiration and photosynthesis.< Réduire

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Critical soil moisture thresholds of plant water stress in terrestrial ecosystems

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