Drivers and Impacts of Smoldering Peat Fires in the Great Dismal Swamp

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2022-05-26
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Virginia Tech
Abstract

Peatlands are a diverse type of wetland ecosystem, characterized by high levels of soil organic matter, that provide a wide array of ecosystem services including water storage and filtration, carbon sequestration, and unique habitats. Draining peatlands degrades their resilience to future disturbances, notably including high intensity, soil-consuming fires. Peat soil fires are unique in that they can smolder vertically through the soil column, with consequences ranging from large carbon emissions to altered hydrology and dramatic shifts in vegetation communities. In this work we had two complementary objectives to understand both the drivers and impacts of smoldering fires at the Great Dismal Swamp (VA and NC, USA). First, we developed and verified a new method to model peat burn depths with readily available water level and peat hydraulic property data. Our findings suggest that drainage weakens both short- and long-term controls on peat burn depths by reducing soil moisture and by decreasing peat water holding capacity. To address the impacts of smoldering fires, we quantified the abundance of the noxious Phragmites australis in a large fire scar and the extent to which altered hydrology influenced its occurrence. We did so by leveraging satellite imagery, random forest models, LiDAR data, and water table observations. Our results suggest that P. australis is aided by a hydrologic regime generated, in part, from the combined effects of drainage and deep smoldering fires. Our conclusions from these two studies contribute to the scientific understanding of smoldering peat fires and can inform management efforts.

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Fire, Hydrology, Peat, Invasive Species, Soil Moisture Modeling, Remote Sensing, HYDRUS 1-D, Phragmites australis
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