Project Title

Quantifying soil hydrologic properties to inform wetland remediation strategies in the Daniel Boone National Forest, Kentucky

Presenter Information

James FL Thompson, StudentFollow

Presenter Hometown

Owenton

Major

Geology/GIS

Department

Geosciences

Degree

Undergraduate

Mentor

Jonathan malzone

Mentor Department

Geosciences

Abstract

Adding constructed wetlands to public lands has been a strategy to recover wetlands lost due to development. In the Daniel Boone National Forest (DBNF), KY, constructed wetlands meant to resemble local ridge top vernal pools have been made to expand native amphibian and bat habitats. However, the constructed wetlands do not exhibit the same hydrologic and ecological properties as their natural counterparts, because they tend to remain wet annually and encourage the inhabitation of invasive species. One reason for the discrepancy may be the process used to construct wetlands, as it involves mixing and compacting the soil. In order to better manage the landscape, the United States Forest Service wants to develop strategies for deconstructing constructed wetlands towards target parameters. In this research, we collected soil samples from DBNF and conducted lab experiments that define the hydrologic properties of the soil under variable compaction and saturation in order to quantify how deconstruction strategies need to change the soil. Soil hydraulic conductivity, dry density, and moisture retention curves were computed for native and constructed soil, as well as for constructed soil that was compacted to different densities in the lab. Our results show that the construction process steepens the moisture retention curve, in addition to reducing the soil’s conductivity, which greatly decreases the unsaturated hydraulic conductivity when compared to undisturbed soil. This is important because it means that a deconstruction process that reduces soil density may not achieve undisturbed soil conditions and needs to consider additional strategies to achieve native hydrology.

Presentation format

Poster

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Quantifying soil hydrologic properties to inform wetland remediation strategies in the Daniel Boone National Forest, Kentucky

Adding constructed wetlands to public lands has been a strategy to recover wetlands lost due to development. In the Daniel Boone National Forest (DBNF), KY, constructed wetlands meant to resemble local ridge top vernal pools have been made to expand native amphibian and bat habitats. However, the constructed wetlands do not exhibit the same hydrologic and ecological properties as their natural counterparts, because they tend to remain wet annually and encourage the inhabitation of invasive species. One reason for the discrepancy may be the process used to construct wetlands, as it involves mixing and compacting the soil. In order to better manage the landscape, the United States Forest Service wants to develop strategies for deconstructing constructed wetlands towards target parameters. In this research, we collected soil samples from DBNF and conducted lab experiments that define the hydrologic properties of the soil under variable compaction and saturation in order to quantify how deconstruction strategies need to change the soil. Soil hydraulic conductivity, dry density, and moisture retention curves were computed for native and constructed soil, as well as for constructed soil that was compacted to different densities in the lab. Our results show that the construction process steepens the moisture retention curve, in addition to reducing the soil’s conductivity, which greatly decreases the unsaturated hydraulic conductivity when compared to undisturbed soil. This is important because it means that a deconstruction process that reduces soil density may not achieve undisturbed soil conditions and needs to consider additional strategies to achieve native hydrology.