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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 19 | Copyright
Biogeosciences, 12, 5689-5704, 2015
https://doi.org/10.5194/bg-12-5689-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 08 Oct 2015

Research article | 08 Oct 2015

Modeling micro-topographic controls on boreal peatland hydrology and methane fluxes

F. Cresto Aleina1,2, B. R. K. Runkle3,4, T. Kleinen1, L. Kutzbach3, J. Schneider5, and V. Brovkin1 F. Cresto Aleina et al.
  • 1Max Planck Institute for Meteorology, Hamburg, Germany
  • 2Max Planck Institute for Biogeochemistry, Jena, Germany
  • 3Institute of Soil Science, Center for Earth System Research and Sustainability, Universität Hamburg, Hamburg, Germany
  • 4Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR, USA
  • 5Institute for Environmental Sciences, University of Koblenz-Landau, Landau in der Pfalz, Germany

Abstract. Small-scale surface heterogeneities can influence land-atmosphere fluxes and therefore carbon, water and energy budgets on a larger scale. This effect is of particular relevance for high-latitude ecosystems, because of the great amount of carbon stored in their soils. We introduce a novel micro-topographic model, the Hummock-Hollow (HH) model, which explicitly represents small-scale surface elevation changes. By computing the water table at the small scale, and by coupling the model with a process-based model for soil methane processes, we are able to model the effects of micro-topography on hydrology and methane emissions in a typical boreal peatland. In order to assess the effect of micro-topography on water the balance and methane emissions of the peatland we compare two versions of the model, one with a representation of micro-topography and a classical single-bucket model version, and show that the temporal variability in the model version with micro-topography performs better if compared with local data. Accounting for micro-topography almost triples the cumulative methane flux over the simulated time-slice. We found that the single-bucket model underestimates methane emissions because of its poor performance in representing hydrological dynamics. The HH model with micro-topography captures the spatial dynamics of water and methane fluxes, being able to identify the hotspots for methane emissions. The model also identifies a critical scale (0.01 km2) which marks the minimal resolution for the explicit representation of micro-topography in larger-scale models.

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We developed a process-based model for peatland micro-topography and hydrology, the Hummock-Hollow (HH) model, which explicitly represents small-scale surface elevation changes. By coupling the HH model with a model for soil methane processes, we are able to model the effects of micro-topography on hydrology and methane emissions in a typical boreal peatland. We also identify potential biases that models without a micro-topographic representation can introduce in large-scale models.
We developed a process-based model for peatland micro-topography and hydrology, the...
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