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. / Master of Science / Peatlands are a diverse type of wetland ecosystem that have characteristically thick levels of organic-rich soil, known as peat. Peatlands are home to a variety of unique plants and animals, store large amounts of carbon, and provide water storage functions. Peatlands were historically drained to enable development and conversion to other land usages, which had many unintended consequences like increasing their risk to wildfires that consume soil organic matter. An intense peat fire can smolder down through the peat, with impacts ranging from large releases of carbon to changes in water levels and vegetation communities. In this work we had two objectives aimed at understanding the drivers and impacts of smoldering peat fires in the Great Dismal Swamp (GDS) (VA and NC, USA). First, we developed and verified a new method of modeling how deep peat fires burn by using readily available water level and soil property data. Our findings suggest that drainage weakens both the short- and long-term controls on peat fire burn depths by reducing soil moisture and by limiting the ability of peats to hold water. We also studied how water levels in a post-peat consuming fire environment influence the amount of the weedy Phragmites australis. We did so by using satellite imagery, elevation data, and water table observations. Results from this investigation suggest that the combined effects of drainage and deep smoldering fires help to create ideal conditions for P. australis invasion and establishment. Our findings from these two studies add to the scientific understanding of smoldering peat fires and may inform land management decisions.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/110348 |
| Date | 26 May 2022 |
| Creators | Link, Nicholas Turner |
| Contributors | Forest Resources and Environmental Conservation, McLaughlin, Daniel L., Strahm, Brian D., Varner, Julian Morgan, Stewart, Ryan D. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Coverage | Virginia, North Carolina, United States |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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