EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Peatlands methane origin and fluxes to the atmosphere: towards an integrative conceptual model of a temperate French peatland

Alexandre Lhosmot1, Adrien Jacotot2,3, Marc Steinmann1, Laure Gandois4, Philippe Binet1, Marie-Laure Toussaint1, Sébastien Gogo5, Daniel Gilbert1, Jean-Sébastien Moquet2, Sarah Coffinet5, Anne Boetsch1, Christophe Loup1, Fatima Laggoun-Défarge2, and Guillaume Bertrand1,6
Alexandre Lhosmot et al.
  • 1Chrono-Environnement, UMR 6249, Université de Franche-Comté, CNRS, Besançon, Montbéliard, France
  • 2Institut des Sciences de la Terre d'Orléans (ISTO), UMR 7327, Université d’Orléans, CNRS, Orléans, France
  • 3Sol, Agro et hydrosystèmes, Spatialisation (SAS), UMR 1069, INRAE, Institut Agro, Rennes, France
  • 4Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), UMR 5245, Université de Toulouse, CNRS, Toulouse, France
  • 5ECOBIO, UMR 6553, Université de Rennes, CNRS, Rennes, France
  • 6Water Resources and Environmental Engineering Laboratory, Federal University of Paraíba, 58051-900 Joao Pessoa, Brazil

Peatlands cover only 3 % of emerged lands, but their carbon stock represents about 30 % of the global soil organic carbon. Climate change and local anthropogenic disturbances deeply affect the hydrological functioning of peatlands. This may trigger carbon fluxes to surface waters and the atmosphere, thus leading to a positive feedback for global warming. It is therefore crucial to better estimate carbon fluxes between peatlands and the atmosphere and to delineate their major controlling constraints. To achieve this goal, we studied the functioning of a temperate mid-mountain peatland located in the French Jura Mountains, named the Frasne peatland.

The methane (CH4) dynamics of the Frasne peatland appear to be constrained by a range of hydrological, physical, biogeochemical, and biotic factors. From a hydrological point of view, the system is fed by local rainwater and injection of carbonated groundwater at the bottom of the peatland, which provides a major input of dissolved inorganic carbon (DIC) to the system. Values of the δ13CDIC were high (even reaching positive values up to 8.1 ‰) compared to the expected values in a limestone and C3 plant-dominated area such as the Jura Mountains, supporting biotic CH4 production within the peatland. Consistently, high-frequency eddy-covariance monitoring during 2.5 years allowed us to show that the site acted as a source of CH4 to the atmosphere (23.9 ± 0.6 g C m-2 year-1) with interannual, seasonal, and diurnal time scale dynamics. In particular, we found an outstanding diurnal cycle for CH4 with the highest fluxes at night and lower ones at mid-day. In addition, the mid-day fluxes were negative in spring, highlighting larger oxidative processes than CH4 production attributed to photosynthesis activity (i.e., soil oxygen penetration and endosymbiotic methanotrophs of Sphagnum). The range of CH4 emissions was also controlled by the interannual variation in precipitation amounts and by the seasonal temperature variation.

This conceptual production-emission model highlights that water-carbon interactions in the peatland depend on local biotic and abiotic factors but also on hydrological processes at the watershed scale. This also highlights the need to further constrain carbon transfers between the production and the emission zones (i.e., peatland-atmosphere interface and surface water exports). For this purpose, we will soon carry out a field campaign to measure the concentrations and isotopic values of dissolved gases in peat pore water along with an upstream downstream and a vertical gradient.

How to cite: Lhosmot, A., Jacotot, A., Steinmann, M., Gandois, L., Binet, P., Toussaint, M.-L., Gogo, S., Gilbert, D., Moquet, J.-S., Coffinet, S., Boetsch, A., Loup, C., Laggoun-Défarge, F., and Bertrand, G.: Peatlands methane origin and fluxes to the atmosphere: towards an integrative conceptual model of a temperate French peatland, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-13093,, 2023.