Critical soil moisture thresholds of plant water stress in terrestrial ecosystems
Language
en
Article de revue
This item was published in
Science Advances. 2022, vol. 8, n° 44, p. eabq7827
American Association for the Advancement of Science (AAAS)
English Abstract
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 ...Read more >
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.Read less <
Origin
Hal imported