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.

https://doi.org/10.3390/f10010014

Article de revue ; Article de recherche ; Article de revue à facteur d'impact Revue en libre accès total

Prévisualisation

Version publiée - Anglais
Sous licence

.
Aguilos et al. - 2019 - Interannual and Seasonal Variations in Ecosystem Transpiration and Water Use Efficiency in a Tropical Rainforest.pdf
Télécharger (4MB) | Prévisualisation

Quartile : Q1, Sujet : FORESTRY

Résumé : 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, France

Classification Agris : K01 - Foresterie - Considérations générales
F40 - Écologie végétale
F60 - Physiologie et biochimie végétale
P40 - Météorologie et climatologie

Champ stratégique Cirad : CTS 6 (2019-) - Changement climatique

Agences de financement européennes : European Regional Development Fund

Auteurs et affiliations