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Seminar | Environmental Science Division

Linking Biogeochemical and Geomorphic Processes to Further Our Understanding of Soil Organic Matter Dynamics

EVS Seminar

Abstract: Most of the earth’s terrestrial ecosystem is composed of sloping landscapes, where soil organic matter dynamics is partly controlled by the mass movement events that laterally distribute topsoil. Accurate estimation of the global carbon stock or the potential of soils to sequester atmospheric carbon dioxide are complicated by the effects of soil redistribution on both net primary productivity and decomposition. Studies over the last two decades arrived at contradictory results as to whether soil erosion constitutes a net source or sink term with respect to atmospheric carbon dioxide.

In this presentation, I will discuss why and how soil erosion can constitute a C sink by (a) defining the criterion necessary for erosion to constitute a C sink; (b) comparing the rates of soil organic matter decomposition at eroding and depositional settings; and © identifying the potential for soils to provide protective surfaces (physical and chemical stabilization mechanisms) for soil organic matter in dynamic landscapes.

Bio: Asmeret Asefaw Berhe’s research is broadly focused on soil science and global change science. The main goal of her research is to understand the effect of changing environmental conditions on vital soil processes, most importantly the cycling and fate of essential elements in the critical zone. She studies soil processes in systems experiencing natural and/or anthropogenic perturbation in order to understand fundamental principles governed by geomorphology, and contemporary modifications introduced by changes in land use and climate.