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Interannual and seasonal variations in ecosystem transpiration and water use efficiency in a tropical rainforest

Aguilos Maricar, Stahl Clément, Burban Benoit, Herault Bruno, Courtois Elodie A., Coste Sabrina, Wagner Fabien, Ziegler Camille, Takagi Kentaro, Bonal Damien. 2019. Interannual and seasonal variations in ecosystem transpiration and water use efficiency in a tropical rainforest. Forests, 10:14, 20 p.

Journal article ; Article de recherche ; Article de revue à facteur d'impact Revue en libre accès total
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Quartile : Q1, Sujet : FORESTRY

Abstract : Warmer and drier climates over Amazonia have been predicted for the next century with expected changes in regional water and carbon cycles. We examined the impact of interannual and seasonal variations in climate conditions on ecosystem-level evapotranspiration (ET) and water use efficiency (WUE) to determine key climatic drivers and anticipate the response of these ecosystems to climate change. We used daily climate and eddyflux data recorded at the Guyaflux site in French Guiana from 2004 to 2014. ET and WUE exhibited weak interannual variability. The main climatic driver of ET and WUE was global radiation (Rg), but relative extractable water (REW) and soil temperature (Ts) did also contribute. At the seasonal scale, ET and WUE showed a modal pattern driven by Rg, with maximum values for ET in July and August and for WUE at the beginning of the year. By removing radiation effects during water depleted periods, we showed that soil water stress strongly reduced ET. In contrast, drought conditions enhanced radiation-normalized WUE in almost all the years, suggesting that the lack of soil water had a more severe effect on ecosystem evapotranspiration than on photosynthesis. Our results are of major concern for tropical ecosystem modeling because they suggest that under future climate conditions, tropical forest ecosystems will be able to simultaneously adjust CO2 and H2O fluxes. Yet, for tropical forests under future conditions, the direction of change in WUE at the ecosystem scale is hard to predict, since the impact of radiation on WUE is counterbalanced by adjustments to soil water limitations. Developing mechanistic models that fully integrate the processes associated with CO2 and H2O flux control should help researchers understand and simulate future functional adjustments in these ecosystems.

Mots-clés Agrovoc : Forêt tropicale humide, Écosystème forestier, Évapotranspiration, Changement climatique, Saison

Mots-clés géographiques Agrovoc : Guyane française

Classification Agris : K01 - Forestry - General aspects
F40 - Plant ecology
F60 - Plant physiology and biochemistry
P40 - Meteorology and climatology

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Agence(s) de financement européenne(s) : European Regional Development Fund

Auteurs et affiliations

  • Aguilos Maricar, INRA (GUF)
  • Stahl Clément, INRA (GUF)
  • Burban Benoit, INRA (FRA)
  • Herault Bruno, CIRAD-ES-UPR Forêts et sociétés (CIV) ORCID: 0000-0002-6950-7286
  • Courtois Elodie A., Université de Guyane (GUF)
  • Coste Sabrina, INRA (GUF)
  • Wagner Fabien, INPE (BRA)
  • Ziegler Camille, INRA (GUF)
  • Takagi Kentaro, Hokkaido University (JPN)
  • Bonal Damien, Université de Lorraine (FRA) - auteur correspondant

Source : Cirad-Agritrop (https://agritrop.cirad.fr/591352/)

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