Defense Date
2025
Document Type
Thesis
Degree Name
Master of Science
Department
Biology
First Advisor
Julie Zinnert
Abstract
Barrier island migration is occurring in response to sea-level rise (SLR), yet upland vegetation feedback mechanisms remain underrepresented in prediction models. This study examines spatial and temporal patterns of marsh-to-upland conversion across barrier islands in the Virginia Coast Reserve (VCR) from 1984-2021 and characterizes ecological processes occurring on the marsh/upland boundary of Metompkin Island, Virginia. Thirteen Landsat images (~2-4 years apart) were classified into landcover classes (bare, grass, woody, marsh, ocean) and analyzed at the island and sub-island scale through landcover change matrices to calculate marsh-to-upland conversion rates, where upland includes bare, grass, and woody classes. Multiple regression analyzed the effect of the landcover composition and marsh/upland width on marsh-to-upland conversion. Field data from Metompkin Island, including vegetation cover and soil characteristics, were used to characterize the ecotone of the marsh/upland boundary. Landcover analysis revealed that marsh-to-upland conversion rates were spatially and temporally variable, but increased over time. Rates were consistently high across all transects and islands from 2016 2021, coinciding with an above-average frequency of major storms. At the sub-island scale, woody vegetation and upland width were negatively correlated with conversion, though these relationships were masked at the island scale. The influence of woody vegetation on migration appeared in top models during periods of lower relative marsh-to-upland change, indicating that the influence may be greater during periods of stability and reduced storminess. At the island scale, percent marsh-to-upland conversion, which controlled for island size, better revealed patterns of migration for smaller islands. At the marsh/upland boundary, vegetation and soil characteristics varied based on freshwater availability. These results will improve barrier island migration models that are important for conservation planning as islands face increasing development pressure, SLR, and more frequent and intense storms.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
12-9-2025
Included in
Climate Commons, Environmental Monitoring Commons, Geomorphology Commons, Other Earth Sciences Commons, Other Environmental Sciences Commons, Other Plant Sciences Commons