LE STUDIUM RESEARCH FELLOW / ARD 2020 - PIVOTS Programme
Dr Fatima Laggoun Défarge & Dr Sébastien Gogo
Role of microorganisms in the Carbon Cycling of Peatlands
Considered among the world’s largest carbon sinks, peatlands play a key role in the global carbon cycle. Globally, they keep 1/3 of the carbon stored in the soil, produce about 25% of the methane (CH4) and export substantial amounts of dissolved carbon to aquatic environments. Carbon cycling in peatlands is limited by a slowed microbial degradation of dead plant organic matter (POM) due to constrained environmental conditions, i.e. high concentrations of phenolic compounds, low pH, and anoxic conditions. POM’s polymers are degraded by extracellular enzymes activities (EEA) produced by microorganisms, eventually resulting in the emission of CH4 and CO2 to the atmosphere.
Peatland are broadly distributed, although they are more abundant in the northern hemisphere (Canada and Russia). Environmental variations, both natural or anthropogenic, such as the change in temperature, soil water, pH, nutrients or oxygen concentration, may affect POM processing by microorganisms and in consequence the total carbon cycle and gas emissions. Mechanisms behind to the factors controlling POM processing in peatlands are still poor understood, and the present project aims to improve our understanding of those mechanisms in French peatlands. During her stay, the fellow is supporting an existing research project (GHG Exchange between Soils and the Atmosphere in peatland - PESAt) at the host laboratory. The fellow is developing the experimental protocol to measure EEA in peat soil and water in the host lab and is studying the microbial metabolism (EEA) in relation to two environmental factors, temperature and soil depth in the La Guette peatland (a long-term study site of the ISTO’s peatlands group).