Three-Dimensional Modeling of the Coevolution of Landscape and Soil Organic Carbon

Qina Yan, Phong V.V. Le, Dong K. Woo, Tingyu Hou, Timothy Filley, Praveen Kumar

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Soil organic carbon (SOC) is going through rapid reorganization due to anthropogenic influences. Understanding how biogeochemical transformation and erosion-induced SOC redistribution influence SOC profiles and stocks is critical to our food security and adaptation to climate change. The important roles of erosion and deposition on SOC dynamics have drawn increasing attention in the past decades, but quantifying such dynamics is still challenging. Here we develop a process-based quasi 3-D model that couples surface runoff, soil moisture dynamics, biogeochemical transformation, and landscape evolution. We apply this model to a subcatchment in Iowa to understand how natural forcing and farming practices affect the SOC dynamics in the critical zone. The net soil thickness and SOC stock change rates are −0.336 (mm/yr) and −1.9 (g C/m2 /year), respectively. Our model shows that in a fast transport landscape, SOC transport is the dominant control on SOC dynamics compared to biogeochemical transformation. The SOC profiles have “noses” below the surface at depositional sites, which are consistent with cores sampled at the same site. Generally, erosional sites are local net atmospheric carbon sinks and vice versa for depositional sites, but exceptions exist as seen in the simulation results. Furthermore, the mechanical soil mixing arising from tillage enhances SOC stock at erosional sites and reduces it at depositional ones. This study not only helps us understand the evolution of SOC stock and profiles in a watershed but can also serve as an instrument to develop practical means for protecting carbon loss due to human activities.

Original languageEnglish
Pages (from-to)1218-1241
Number of pages24
JournalWater Resources Research
Volume55
Issue number2
DOIs
StatePublished - Feb 2019
Externally publishedYes

Funding

support from National Science Foundation Grants EAR 1331906 (Intensively Managed Landscapes Critical Zone Observatory, IML-CZO) and CBET 1290445, ACI 1261582 (BrownDog) are gratefully acknowledged. We also acknowledge Alison Anders and Asmeret Berhe for insightful discussions. Thanks to Debsunder Dutta for his help on processing Landsat data set. We also thank Ming Li and Ulyssa Hester for assistance in the laboratory processing of the soil core samples. Thanks to the workshop, \u201CMathematical Modeling of Earth's Dynamic Systems,\u201D hosted at Penn State in Summer 2016 for its travel grant to Qina Yan. The authors declare no conflict of interest. The Landsat 7 ETM+ C1 Level-1 data product was retrieved from the online Data Pool, courtesy of the NASA Land Processes Distributed Active Archive Center (LP DAAC), USGS/Earth Resources Observation and Science (EROS) Center, Sioux Falls, South Dakota, https://earthexplorer. usgs.gov/. The 10-year recorded meteorological data were retrieved from weather underground, https://www.wunderground.com/ weather/us/ia/iowa-city/. Data of LiDAR DEM and soil core samples used in this research are openly available at https://github.com/ HydroComplexity/SCALE.

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