Date of Award

Spring 2021

Project Type

Thesis

Program or Major

Biological Sciences

Degree Name

Master of Science

First Advisor

Gregg E Moore

Second Advisor

David M Burdick

Third Advisor

Susan C Adamowicz

Abstract

The impacts of Superstorm Sandy on coastal resources of the eastern United States have brought the importance of resilient sand dune systems into focus. While dunes are primarily dominated by American beachgrass (Ammophila breviligulata), a host of other native species commonly occur in these systems, providing diversity and habitat complexity that is often not recognized or incorporated into dune restoration initiatives, and could benefit sites where dune dieout is a concern. Dieout refers to the death of A. breviligulata occurring in large patches. The goal of this study was to explore the importance of biodiversity on dune resiliency by using a variety of native species (in addition to A. breviligulata) to stabilize and revegetate dunes impacted by coastal storms, foot traffic, encroachment and other impacts in dunes on the north shore of Massachusetts. Chapter I examines the natural history of Plum Island, Newbury, Massachusetts. Chapter II details how field experiments were used to determine which native dune species may be well suited for restoration by recording plant survivorship, growth rate, and relative ability to trap and accrete windblown sand in foredune habitats. Comparisons were also made to examine the differences in sand accretion capability of three experimental treatments: 1) a single species (A. breviligulata only), 2) a low diversity (A. breviligulata with Solidago sempervirens), and 3) higher diversity plots (A. breviligulata with S. sempervirens, Lathyrus japonicus, and Cakile edentula). Finally, diversity and percentage cover were compared between control site (healthy, natural dunes) versus restoration areas and dunes exhibiting signs of dune dieout. Based upon the results of three planting efforts, S. sempervirens and L. japonicus appear to be best suited for restoration plantings. However, relative sand accretion was not affected by diversity level (low or high). Instead, sand accretion was most affected by proximity to the ocean. As expected, percentage cover was greatest in the reference sites, compared to the restoration areas and dunes with dieout. However, plant species diversity was greatest in dieout areas. While the benefits of diversity (structural, habitat, and ecological complexity) are essential to maintaining functional coastal ecosystems, the quantitative effects of diversity on dune resiliency will require further study to determine the species, planting methods, and planting times required for restoration efforts. Finally, Chapter III describes how this research was incorporated into local Science, Technology, Engineering, Art, and Math (STEAM) initiatives.

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