Modelling interranual variability of methane emissions from a temperate degraded peatland

Wetlands are the largest natural source of methane in the atmosphere. How the methane emissions from wetlands will evolve with global change is a subject of debate. In this study, we investigate the interannual variability of methane emissions from a temperate degraded peatland located in the Sologne region (French Region Centre) and test the ability of the land surface model ORCHIDEE to reproduce this variability. The site is instrumented for long term monitoring of the hydrological parameters, greenhouse gas emissions, dissolved organic content and biodiversity. The peat has undergone several perturbations due to the urbanization of the site that led to drainage and invasion by vascular plants (Molinia Caerula, Erica Tretalix). Our study focuses on the 2014-2020 period after a hydrological restoration was undertaken. The model, driven by meteorological data and constrained by in situ hydrological data, primary productivity and total soil carbon, is able to reproduce the general temporal trend in methane emissions. The model is used to investigate the effect of climatological conditions (droughts) and vegetation changes (invasion by vascular plants) on the observed trend of methane fluxes. The model is also used to study the relative contributions of different methane transport processes (by the plants, from ebullition and diffusion) to the methane flux observed in La Guette peatland.