In this dissertation, I investigate the interactions of two invasive, dune-forming beachgrasses within the U.S Pacific Northwest coastal dune ecosystem and their influence on dune geomorphology and ecosystem services. Overall, the findings from this dissertation research demonstrates the complex and interdependent connection between biological invasions and climate change on community structure, ecological processes, and ecosystem services of the U.S. Pacific Northwest coastal dunes. For management of coastal dunes, this research examines multiple factors that may contribute to the present-day distribution and abundance of the two Ammophila species, and their potential to spread to new areas in the coming decades. Moreover, I demonstrated why the two Ammophila species produce distinct dune shapes and resultantly exhibit differing amounts of protection against flooding and erosion hazards. Finally, although I found that Ammophila removal for plover conservation created tradeoffs in ecosystem service supply, strategic management can minimize tradeoff severity and alleviate potential conflicts among stakeholders. For Pacific Northwest coastal management, these findings can help to inform coastal managers of the potential for changes in the distribution of the two Ammophila species, their impacts on dune ecosystems and the services that they provide, and some possible strategies possible strategies for establishing new habitat restoration areas for endangered species while managing resources for multiple stakeholders.


Author: Biel, Reuben Gabriel

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256 pages
Oregon State University
Doctorate in Zoology, Department of Integrative Biology