3e série de séminaires CLIMACT - Episode #6
Mapping Carbon Flow through Soils: Ecosystem and Global Impacts
Soils contain the largest dynamic stock of carbon (C) on the planet, with soil organic matter (SOM) containing approximately twice the amount of C stored in the surface oceans and three-times that in the atmosphere. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily—and this limits our ability to predict how soils will respond to climate and land use change. Recent analytical and experimental advances have undermined the long-standing theory that molecular structure alone controls SOM turnover; instead, SOM turnover is now considered an ecosystem property, rendering associated C stocks much more vulnerable to environmental change. In this talk, I will highlight how plants, microbes, and minerals interact to regulate SOM turnover within soil ecosystems. I will further show that explicit consideration of such ecosystem controls, together with climatic variables, is critical for improved predictions of soil carbon-climate feedbacks as well as management strategies aimed at sustaining soil health.
Prof. Marco Keiluweit
Professor at the Faculty of Geosciences and Environment, UNIL
Marco Keiluweit is interested in how carbon and nutrient cycles in soil and sediments respond to climate and land use change. He completed his PhD at Oregon State University, and worked as a postdoc at Stanford University and an Assistant Professor at the University of Massachusetts-Amherst. He is now Associate Professor of Soil Biogeochemistry at UNIL. Marco Keiluweit is particularly interested in fundamental geochemical processes, biotically-mediated or not, that regulate carbon and nutrient cycles in soils. His research combines laboratory, greenhouse, and field experiments with advanced analytical tools such as synchrotron spectroscopy, chemical imaging, and molecular microbiology. His group’s work links fine-scale biogeochemical mechanisms to landscape-scale processes within natural and managed ecosystems. Marco Keiluweit has acquired numerous grants and has received several prestigious awards, including a Lawrence Scholar and the NSF Early Career award.
Electron transfer reactions in soils: implications for biogeochemical element cycling
Electron transfer (redox) reactions are central to the transformation of energy in the environment and play an important role in the cycling of elements. In soils, one of the main drivers of carbon cycling is the activity of organisms that utilize the energy stored in soil organic matter by extracting electrons from organic carbon and transferring them to various electron acceptors. Yet, our understanding of this process is incomplete and the response of the soil carbon pool to climate change remains one of the primary sources of uncertainty in projections of atmospheric carbon dioxide concentrations. Here, I highlight the relevance of redox reactions in soils and, specifically, the role of redox-active minerals in soil carbon cycling under oxygen-limited conditions.
Prof. Meret Aeppli
Professor at the Soil biogeochemistry Laboratory of ENAC, EPFL
Meret Aeppli is an assistant professor and head of the soil biogeochemistry laboratory at EPFL. Before joining EPFL, Meret was a postdoctoral fellow at Stanford University in the department of Earth System Science from 2019 to 2022. She holds a Bachelor's and a Master's degree in Environmental Sciences from ETH Zurich and obtained her PhD from ETH Zurich in 2018.