Berhe, A. A.

Doetterl, Sebastian

Finke, Peter

Harden, Jennifer

English

OPUS Augsburg

Geophysical Research AbstractsVol. 21, EGU2019-4010, 2019EGU General Assembly 2019© Author(s) 2019. CC Attribution 4.0 license.Mineral weathering diversifies the response of soil carbon and microbialdynamics to warmingSebastian Doetterl (1,2), Asmeret Asefaw Berhe (3), Peter Finke (4), Jennifer Harden (5,6)(1) Terrestrial Ecosystems, Environmental Systems Science, ETH Zurich, Zürich, Switzerland (sdoetterl@usys.ethz.ch), (2)Institute of Geography, Augsburg University, Augsburg, Germany, (3) Life and Environmental Sciences, University ofCalifornia at Merced, Merced, United States, (4) Department of Environment, Ghent University, Gent, Belgium, (5) SoilBiogeochemistry Research group, US Geological Survey, Menlo Park, United States, (6) School of Earth, Energy &Environmental Sciences, Stanford University, Stanford, United StatesQuantifying soil carbon dynamics is of utmost relevance in the context of global change because soils play animportant role in land-atmosphere gas exchange. Our current understanding of both present and future carbondynamics is limited because we fail to accurately represent soil processes across temporal and spatial scales,partly because of the paucity of data on the relative importance and hierarchical relationships between microbial,geochemical and climatic controls.Using observations from a 3000 ka soil chronosequence, we show how soil carbon dynamics are driven bythe relationship between short-term biotic responses and long-term mineral weathering. We linked temperaturesensitivity of heterotrophic respiration to biogeochemical soil properties through their relationship with microbialactivity and community composition. In a final step, we tested if the dependencies of soil organic carbon dynamicson mineral properties can be translated into a model framework and help to improve SOC modeling on decadalto millennial timescales using a version of the soil weathering model SoilGen including the functionality of themulti-pool C turnover model RothC.We found that soil mineralogy, in particular changes in mineral reactivity and resulting nutrient availability,impacts the response of heterotrophic soil respiration to warming by altering carbon inputs, carbon stabilization,microbial community composition and extracellular enzyme activity. We demonstrate that biogeochemicalalteration of the soil matrix (and not short-term warming) controls the composition of microbial communitiesand strategies to metabolize nutrients. More specifically, weathering first increases and then reduces nutrientavailability and retention, as well as the potential of soils to stabilize carbon. We conclude that there is a greatbenefit of including geochemical rate modifiers in SOC models that can help to explain the varying importance ofbiotic and abiotic soil components along weathering and geochemical sequences.

Mineral weathering diversifies the response of soil carbon and microbial dynamics to warming

https://opus.bibliothek.uni-augsburg.de/opus4/files/87394/EGU2019-4010.pdf

Mineral weathering diversifies the response of soil carbon and microbial dynamics to warming

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