HYDROSTRATIGRAPHY OF NATURAL AND CONSTRUCTED WETLANDS, DANIEL BOONE NATIONAL FOREST, KENTUCKY

Non-natural or augmented wetlands do not always function in their host landscapes as appropriate ecosystems. For example, hundreds of wetlands have been constructed in Daniel Boone National Forest in the past 30 years to increase critical habitat, but recent studies have found these constructed systems are perennially inundated and act as conduits for invasive species. There are also many naturally occurring ephemeral, perched groundwater wetlands in the area that act as important ecosystems. The hydrology of both wetland types is not well understood. The USFS intends to begin restoring these constructed wetlands to function more like their natural counterparts. However, to begin “deconstructing” these constructed wetlands, more knowledge is needed about their geologic properties. By measuring soil properties such as bulk density, texture, and how easily water flows through its matrix (hydraulic conductivity) for six natural wetlands and five constructed wetlands, we were able to explore the variability of wetland soils in this region, and by mapping the permeability of different soil layers down to bedrock (hydrostratigraphy) we were able to begin understanding the geologic controls of water flow in three natural wetlands. Our results showed that constructed wetlands had more variable hydraulic conductivities despite commonly high clay content and bulk densities while natural soils had a greater variety of soil textures and a narrower range of hydraulic conductivity. Similar techniques could to help inform the evaluation of both constructed and natural wetlands in the upper Midwest as we try to ensure that wetlands function as regionally appropriate ecosystems.