Date of Award
Summer 8-18-2023
Level of Access Assigned by Author
Open-Access Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Wildlife Ecology and Wildlife Conservation
Advisor
Cynthia Loftin
Second Committee Member
Andrew Reeve
Third Committee Member
Aram Calhoun
Additional Committee Members
Christina Murphy
Martin Briggs
Abstract
Globally, groundwater influenced ecosystems (GIEs) are increasingly vulnerable to climate change and anthropogenic modifications. Groundwater management decisions for human use often do not consider ecological effects of those actions on GIEs, which rely on groundwater to maintain ecological function. This disparity can be attributed in part to a lack of information about where these systems are found and relationships with the surrounding landscape that may influence the environmental conditions and associated biodiversity. Knowledge of occurrence of GIEs in the northeastern United States is incomplete; as expanding urban areas alter the regional hydrology, threats to groundwater resources are expected to increase. Despite the importance of these resources to both human and wildlife populations, GIEs in the region are largely unmapped and poorly studied. The objectives of our research were to identify and conduct a vulnerability assessment for GIEs across the northeastern United States across spatial scales relevant for management.
At the region scale, we used an ensemble correlative distribution modeling approach to predict landscape scale suitability for GIEs in two ecologically distinct ecoregions (EPA Level II ecoregions: Atlantic Highlands, Mixed Woods Plains) in the northeastern United States. Results indicated that 1% of the land area in each ecoregion had high suitability for GIE presence. Variables contributing to GIE landscape suitability varied between the ecoregions with suitability in the mountainous Atlantic Highlands ecoregion being influenced mainly by topography derived variables, whereas in the rolling hills Mixed Wood Plains ecoregion geology variables were predicted to greatly influence suitability. At the local scale, we used Landsat Thermal Infrared (TIR) imagery to detect groundwater discharge zones at the land surface with a multi-temporal approach to look at spatial and temporal trends of groundwater discharge in a large peatland complex. We identified river reaches and wetlands that had multiple years of imagery indicating relative thermal stability (potential groundwater discharge). Additionally, we were able to identify significant trends in temperatures over time with temperatures increasing in wetland types in our study area. Our results highlight approaches that can be effectively implemented to identify GIEs at the landscape and local scales that better our understanding of these systems in the northeast.
We estimated pixel (30 m x 30 m pixels) and watershed (HUC12) scale vulnerability with variables describing adaptive capacity (topographic wetness index, hydric soil, physiographic diversity), exposure (climatic niche), and sensitivity (aquatic barriers, proportion developed or agriculture). Approximately, 26% of GIEs are potentially vulnerable with 40% being vulnerable to climate exposure and 19% vulnerable to land use practices (agriculture and developed lands). Precipitation of the warmest quarter and driest month were the most important predictors of GIE climatic niche, suggesting that GIEs could be most impacted by climate effects that change or alter precipitation patterns. Results from our vulnerability analysis indicate that the persistence of GIEs in the northeast could be linked to the timing and frequency of precipitation and that effects of climate change could pose the most substantial threat to GIEs in the northeast.
Recommended Citation
Snyder, Shawn D., "Identification and Vulnerability Assessment of Groundwater Influenced Ecosystems in the Northeastern United States" (2023). Electronic Theses and Dissertations. 3845.
https://digitalcommons.library.umaine.edu/etd/3845