Dissertation/Thesis Abstract

Ensuring the Persistence of Salt Marsh Habitats
by Gardner, George, Ph.D., Clark University, 2019, 154; 27666768
Abstract (Summary)

This dissertation examines the threats to and cost of salt marsh preservation. Salt marsh habitats have been threatened by a receding coastline brought upon by global warming-induced sea level rise. When this is combined with expanding urban development and shoreline armoring (such as the installation of riprap and bulkheads), a ‘coastal squeeze’ is created where salt marsh habitats gradually diminish. This situation has provided a new role for conservation agencies to play in the preservation of these habitats through the purchase of “transgression zones”, which is land that could become salt marsh through “marsh migration” (the movement of salt marsh onto undeveloped and unarmored uplands).

Unfortunately, in many cases it can be difficult for these conservation agencies to obtain accurate cost estimates for the purchase of land for preservation purposes. The first chapter introduces a hedonic model designed to forecast the cost of land that may serve as a transgression zone. The model takes into account various geospatial characteristics that would make the land suitable (or not) for salt marsh habitats. The cost of purchase is determined by several factors including the type of land (forest or farm), coastal proximity, elevation, and level of connectivity. The accuracy of model cost predictions is demonstrated when the model is used to predict the cost of land expected to have marsh migration in several long-run sea level rise scenarios. When model cost predictions are compared to cost predictions using averages (the average cost of forest, farm, or all land expected to have marsh migration) the model predictions are superior. In general, cost predictions vary by land type and sea level rise scenarios, and predictions are most accurate when including features relevant to marsh migration.

The potential loss of salt marsh habitats warrants an understanding of their value. This is the focus of the second chapter. A hedonic model is developed to examine the value of salt marshes through their effect on residential property values. The model includes various spatial attributes (proximity and area measures) in order to fully measure the effect. Results show that salt marsh has a positive impact on property values with greater amounts located within a 250 to 500-meter buffer of the home and a negative impact with greater amounts located on the parcel itself.

Although armoring is a major contributor to the issue of coastal squeeze few papers in the economics literature have examined its determinants, and none have examined the influence of armoring in relation to salt marshes and marsh migration. The third chapter examines the factors that influence the likelihood of (riprap and bulkhead) armoring, with an emphasis on those related to marsh migration, erosion, and flooding. The evidence shows armoring taking place away from salt marsh habitats and areas suited to marsh migration. The primary driver of armoring is erosion risk, rather than flood and marsh migration risk.

Indexing (document details)
Advisor: Johnston, Robert J.
Commitee: Geogheghan, Jacqueline, Gray, Wayne
School: Clark University
Department: Economics
School Location: United States -- Massachusetts
Source: DAI-A 81/6(E), Dissertation Abstracts International
Subjects: Environmental economics
Keywords: Armoring, Conservation, Hedonic, Salt marsh, Sea-level rise, Transgression
Publication Number: 27666768
ISBN: 9781392518205
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