EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Modeling of soil carbon dynamics, with focus on microbial activity

Elin Ristorp Aas1, Terje Koren Berntsen1, Alexander Eiler2, and Helge Hellevang3
Elin Ristorp Aas et al.
  • 1University of Oslo, Department of Geosciences, Section for Meteorology and Oceanography, Norway
  • 2University of Oslo, Department of Biosciences, Section for Aquatic Biology and Toxicology, Norway
  • 3University of Oslo, Department of Geosciences, Section of Geology and Geophysics, Norway

The representation of soil carbon dynamics is a major source of uncertainty in Earth System Models (ESMs). The terrestrial carbon pool is more than twice the size of the atmospheric pool. Therefore, the role of soil carbon as a source or a sink of atmospheric carbon, and in feedback loops is important to quantify in a changing climate. Decomposition processes of organic matter in soil have often been represented by first order decay equations, which make comparison and validation against observations difficult. Therefore, quantification of the uncertainties  and validation of improved parameterizations are problematic. An emerging approach to tackle these challenges is to represent microbial soil processes explicitly in the models. Following this approach, we have built a process based module that represent the carbon fluxes during soil decomposition, from aboveground litter to soil organic matter (SOM). The role of saprotrophs and mycorrhizal fungi is explicitly represented with separate carbon pools with associated fluxes. On a site level, we compare initial results from the stand alone module with both existing models and observations of carbon pools and fluxes. The observations are from the Norwegian Dovre Mountains, with data from three different alpine communities. These geographic areas are important, because they are subject to changes due to shrubification. In addition, these ecosystems can store large amounts of carbon. By modeling these sites, we gain more insight in the most important processes in soil decomposition, and how different microbial communities affect the carbon dynamics. We will further refine the module by expanding our study with more sites. The long-term objective is to develop an improved module that can be used to represent soil processes in ESMs, and thereby reduce the uncertainty connected to the exchange of carbon between land and atmosphere.

How to cite: Ristorp Aas, E., Koren Berntsen, T., Eiler, A., and Hellevang, H.: Modeling of soil carbon dynamics, with focus on microbial activity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6875,, 2020


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