Nathan Cousteur: CH₄ dynamics

Summary of the mission

CH₄ Dynamics

The role of trees in the methane cycle: development and refinement of a mechanistic model of production and transport

Methane (CH₄) is responsible for around 20 per cent of global warming (IPCC, 2023). However, the contribution of trees to the global methane budget remains one of the main sources of uncertainty (Saunois et al., 2020). Indeed, trees can act as sources, as sinks, or may not emit methane at all, depending on various biotic and abiotic processes. Methane fluxes emitted by trees result from a complex set of mechanisms: production by methanogenic archaea in the soil or within the tree itself, abiotic production, consumption by methanotrophic bacteria, and transport by diffusion or advection via the transpiration stream (Barba et al., 2019). These processes respond differently to variations in environmental conditions such as temperature, soil moisture and UV radiation. Against this background, my PhD research aims to improve our understanding of the factors that control methane fluxes at the tree level.