Post-doctoral Fellow Marie-Liesse Vermeire, will present the Department of Biological Science seminar with a talk entitled, "Evolution of soil organic matter protection mechanisms during pedogenesis, and impact on soil microbial populations". 

In the upper part of the solum of mineral soils, soil organic and mineral constituents co-evolve through pedogenesis, that in turn impacts the stabilization of soil organic matter (SOM) and its transformation by microorganisms. Predicting the evolution of the stock of SOM requires a process-based understanding of its decomposition and stabilization pathways. This seminar will first describe the SOM stabilization mechanisms, then use a study case (a 530-year chronosequence of podzolic soils) to assess their evolution during soil genesis, and the impact on soil microbial populations.

In the chronosequence, we revealed that SOM protection is both time- and horizon-specific. The microbiota also evolve during soil genesis. Fungi dominate in all horizons of the younger soils and in the topsoil of the older soils, while bacteria prevail in the cemented B horizons of older soils. Our results call for considering the microenvironment and parameters inherent to decomposer microorganisms to understand SOM protection processes in soils.