Alexandre Lhosmot->https://chrono-environnement.univ-fcomte.fr/spip.php?page=perso&nom=LHOSMOT&prenom=Alexandre] will present his thesis entitled, "Water and carbon transfers between peatlands, the atmosphere and aquifers, hydrological, geochemical and greenhouse gas flux models of the active peatland of Frasne (Massif du Jura, France)", on Tuesday 21 March 2023 at 2 pm in the Amphi Croisot, (Propédeutique building, la Bouloie, Besançon)
He carried out this work under the supervision of Marc Steinmann and Guillaume Bertrand.
The defense can also be followed in videoconference, link ZOOM on the invitation to download ICI
Composition of the jury:
Mr. Goldscheider Nico, Professor, Karlsruhe Institute of Technology, Germany Rapporteur
Mr. Poulenard Jérôme, Professor, University of Savoie Mont-Blanc, France Rapporteur
Ms. Probst Anne, Director of Research CNRS, University of Toulouse, France Examiner
Ms. Gandois Laure, Research Fellow CNRS, University of Toulouse, France Examiner
Mr. Gaillardet Jérôme, Professor, Univ. Paris Cité, Institut Universitaire de France, France Examiner
Mr. Gilbert Daniel, Professor, Univ. of Franche-Comté, France Examiner
Mr. Steinmann Marc, HDR Lecturer, Univ. from Franche-Comté, France Thesis supervisor
Mr. Bertrand Guillaume, Lecturer, Univ. from Franche-Comté, France Co-director of thesis
Abstract
While the ecosystem services of peatlands have a key role in addressing the challenges of the 21st century - climate, biodiversity, and water resources - they are directly threatened by anthropogenic activities (drainage) and climate change. Understanding the hydrological, biogeochemical and ecological mechanisms associated with the functioning of peatlands at different spatio-temporal scales is therefore fundamental to mitigate these impacts (management, restoration) and to assess the water and carbon dynamics of peatlands over the next few decades. . It is in this context that this work focuses on the functioning of the active peat bog of Forbonnet (municipality of Frasne, Doubs). This peat bog dominated by sphagnum is characteristic of temperate mid-mountain environments and is located in a syncline of a folded and karstified region: the Jura massif. This work has shown that the active peat bog is a system supplied with water by several components: direct precipitation; streams from nearby forested peatlands; and fluxes of carbonate waters feeding the deeper levels of peat. These carbonated waters transited in the syncline, involving transfers of water and/or pressures from a recharge area located on the adjacent anticline. This supply of carbonated water seems to favor the production of CH4 within the active bog, whereas the downstream part of the system (lower marsh and outlet) is not affected by this process. At the peatland-atmosphere interface, the net exchange of 4 at the scale of the active peatland (measured by eddy-covariance) is controlled by the combination of hydrological, physical and physiological factors via photosynthetic activity which can favor the oxidation of CH4 during the day. The GHG fluxes measured according to the typical ecohydrological gradient of peatlands are consistent with the seasonal cycle observed with the eddy-covariance method. However, the response of this gradient to different hydrometeorological conditions is contrasted according to the flows and presents threshold effects.
