An Integrative Model for Soil Biogeochemistry and Methane Processes: I. Model Structure and Sensitivity Analysis

Journal Article · 10 August 2021 · Journal of Geophysical Research. Biogeosciences

DOI: https://doi.org/10.1029/2019JG005468 · OSTI ID:1812811

Ricciuto, Daniel M.  ^[1]; Xu, Xiaofeng  ^[2]; Shi, Xiaoying ^[1]; Wang, Yihui ^[2]; Song, Xia ^[2]; Schadt, Christopher W.  ^[1]; Griffiths, Natalie A.  ^[1]; Mao, Jiafu  ^[1]; Warren, Jeffrey M.  ^[1]; Thornton, Peter E.  ^[1]; Chanton, Jeff  ^[3]; Keller, Jason K. ^[4]; Bridgham, Scott D. ^[5]; Gutknecht, Jessica ^[6]; Sebestyen, Stephen D.  ^[7]; Finzi, Adrien  ^[8]; Kolka, Randall  ^[7]; Hanson, Paul J.  ^[1]

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1. Environmental Sciences Division and Climate Change Sciences Institute Oak Ridge National Laboratory Oak Ridge TN USA
2. Department Biology San Diego State University San Diego CA USA
3. Earth, Ocean, and Atmospheric Sciences Florida State University Tallahassee FL USA
4. Schmid College of Science and Technology Chapman University Orange CA USA
5. Institute of Ecology and Evolution University of Oregon Eugene OR USA
6. Department of Soil, Water, and Climate University of Minnesota St Paul MN USA
7. USDA Forest Service Northern Research Station Grand Rapids MN USA
8. Department of Biology and PhD Program in Biogeoscience Boston University Boston MA USA

Abstract Environmental changes are anticipated to generate substantial impacts on carbon cycling in peatlands, affecting terrestrial‐climate feedbacks. Understanding how peatland methane (CH ₄ ) fluxes respond to these changing environments is critical for predicting the magnitude of feedbacks from peatlands to global climate change. To improve predictions of CH ₄ fluxes in response to changes such as elevated atmospheric CO ₂ concentrations and warming, it is essential for Earth system models to include increased realism to simulate CH ₄ processes in a more mechanistic way. To address this need, we incorporated a new microbial‐functional group‐based CH ₄ module into the Energy Exascale Earth System land model (ELM) and tested it with multiple observational data sets at an ombrotrophic peatland bog in northern Minnesota. The model is able to simulate observed land surface CH ₄ fluxes and fundamental mechanisms contributing to these throughout the soil profile. The model reproduced the observed vertical distributions of dissolved organic carbon and acetate concentrations. The seasonality of acetoclastic and hydrogenotrophic methanogenesis—two key processes for CH ₄ production—and CH ₄ concentration along the soil profile were accurately simulated. Meanwhile, the model estimated that plant‐mediated transport, diffusion, and ebullition contributed to ∼23.5%, 15.0%, and 61.5% of CH ₄ transport, respectively. A parameter sensitivity analysis showed that CH ₄ substrate and CH ₄ production were the most critical mechanisms regulating temporal patterns of surface CH ₄ fluxes both under ambient conditions and warming treatments. This knowledge will be used to improve Earth system model predictions of these high‐carbon ecosystems from plot to regional scales.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1812811
• Journal Information: Journal of Geophysical Research. Biogeosciences, Journal Name: Journal of Geophysical Research. Biogeosciences Journal Issue: 8 Vol. 126; ISSN 2169-8953
• Publisher: American Geophysical Union (AGU)Copyright Statement
• Country of Publication: United States
• Language: English