Wildfire impacts on soil-water retention in the Colorado Front Range, United States

Authors

  • Brian A. Ebel

    Corresponding author
    1. U.S. Geological Survey, National Research Program,Boulder, Colorado,USA
    2. Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado at Boulder,Boulder, Colorado,USA
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Corresponding author: B. A. Ebel, U.S. Geological Survey, National Research Program, 3215 Marine St. Ste. E-127, Boulder, CO 80303, USA. (brian.ebel@colorado.edu)

Abstract

[1] This work examined the plot-scale differences in soil-water retention caused by wildfire in the area of the 2010 Fourmile Canyon Fire in the Colorado Front Range, United States. We measured soil-water retention curves on intact cores and repacked samples, soil particle-size distributions, and organic matter content. Estimates were also made of plant-available water based on the soil-water retention curves. Parameters for use in soil-hydraulic property models were estimated; these parameters can be used in unsaturated flow modeling for comparing burned and unburned watersheds. The primary driver for measured differences in soil-water retention in burned and unburned soils was organic matter content and not soil-particle size distribution. The tendency for unburned south-facing soils to have greater organic matter content than unburned north-facing soils in this field area may explain why unburned south-facing soils had greater soil-water retention than unburned north-facing soils. Our results suggest that high-severity wildfire can “homogenize” soil-water retention across the landscape by erasing soil-water retention differences resulting from organic matter content, which for this site may be affected by slope aspect. This homogenization could have important implications for ecohydrology and plant succession/recovery in burned areas, which could be a factor in dictating the window of vulnerability of the landscape to flash floods and erosion that are a common consequence of wildfire.

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