Date of Award

2023

Degree Name

Biological Sciences

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Dr. Kyle Palmquist, Committee Chairperson

Second Advisor

Dr. Anne Axel

Third Advisor

Dr. Pamela Puppo

Abstract

Coastal habitats provide many ecosystem services, protecting coastlines from storm surges and erosion, diminishing the effects of eutrophication, sequestering large amounts of carbon, and acting as vital wildlife habitat. Sea-level rise and increased storm surge intensity associated with climate change are increasingly disrupting coastal habitats. These disturbances can shift environmental gradients that drive the zonation of coastal vegetation types, driving habitat conversion. Monitoring coastal habitat conversion can improve our understanding of the dynamic effects of climate change on these landscapes. Therefore, our objectives for chapter 1 were to identify and describe the distributions of vegetation types present on Marine Corps Recruit Depot Parris Island (MCRDPI), a barrier island in South Carolina, USA, and to investigate potential evidence of SLR in these types. Our chapter 2 objectives then focused on describing habitat conversion driven by SLR and storm surge over the last 14 years on MCRDPI. First, we established 57 permanent vegetation plots for long-term monitoring of the coastal vegetation types present on the island and characterized the main environmental variables associated with the distributions of these types. Using data from the vegetation surveys, we identified the USNVC Associations that were present on the island and employed supervised deep learning classification to map their distributions. Additionally, we characterized habitat conversion from 2008 to 2022, relating those changes to relative SLR and storm surge activity that occurred during this time. We identified four salt marsh Associations and eight forest or woodland Associations. The distributions of these vegetation types were primarily driven by salinity and elevation gradients. The marsh types dominated the landscape, covering ~57% of the classified area, while forest types covered ~13%. Over the last 14 years, 6.9% (227 ha) of the classified extent of MCRDPI experienced habitat conversion. Most of this conversion occurred between 2015 and 2018, when two intense storm surge events impacted the island. Conversion of wetland to open water was the largest change class, representing approximately 22% of the total habitat conversion that took place over the 14-year period, resulting in a net loss of salt marsh on MCRDPI. While the timeframe in which most of the habitat conversion took place indicates storm surges as the direct source of conversion, the extreme rate of relative SLR that occurred within this period may have degraded upland vegetation prior to these intense disturbances, leaving them vulnerable to and thus exacerbating the storm damage. The vegetation survey framework established here will enhance continued monitoring efforts, which will provide further insight into the effects of climate change on coastal habitat conversion processes and allow the natural resources department on MCRDPI to make informed management decisions. Our change detection efforts indicate that marsh loss is occurring, even over relatively short time frames. Reducing upland infrastructure directly bordering the marsh edge may facilitate marsh migration and prolong the stability of these habitats and thus the ecosystem services that they afford.

Subject(s)

Climate change.

Storm surges.

Habitats & ecosystems.

Environmental degradation.

Sea level -- South Carolina -- Parris Island.

Coast Changes -- South Carolina -- Parris Island.

Vegetation and climate.

Remote sensing.

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