The Role of Vegetation in Determining Dune Morphology, Exposure to Sea-Level Rise, and Storm-Induced Coastal Hazards: A U.S. Pacific Northwest Perspective

  • Peter Ruggiero
  • Sally Hacker
  • Eric Seabloom
  • Phoebe Zarnetske


Coastal foredunes are often the “first line of defense” for backshore infrastructure from the hazards of erosion and flooding, and they are key components of coastal ecosystems. The shape and growth characteristics of coastal foredunes, typically characterized by simple morphometrics such as dune toe and crest elevations, and dune volume, are a product of both physical and biological forces. By influencing foredune shape, these forces ultimately affect the exposure of human populations and ecosystems to extreme storms and sea-level rise. In this chapter, we synthesize field surveys and a suite of interdisciplinary laboratory, mesocosm, and computer modeling experiments that examine the relative role of vegetation in determining dune geomorphology in the U.S. Pacific Northwest (PNW). We focus on how dunes of different shapes result in variable levels of exposure to coastal hazards. Results suggest that PNW dune shape is primarily a function of sediment supply and the geographic distribution of two species of non-native beach grasses (Ammophila arenaria and A. breviligulata). Over recent decades, A. breviligulata (American beachgrass) has increased its dominance over A. arenaria (European beachgrass) on dunes where it was originally planted and has actively spread to new sites formerly dominated by A. arenaria. A species-specific biophysical feedback occurs between sand deposition and beach grass growth habit, resulting in distinctly different dune geomorphologies in locations dominated by these different grass species. The dense, vertical growth habit of A. arenaria allows it to capture more sand, produce more vertical tillers, and build taller, narrower dunes, while the less dense, lateral growth habit of A. breviligulata is more suited for building shorter but wider dunes. The species-specific feedbacks, along with invasion dynamics, have a first order effect on the region’s exposure to coastal hazards, in the present day and under a range of climate change and invasion scenarios. These findings draw on insights from geomorphology, ecology, and coastal engineering to assess coastal barrier vulnerability in light of global change.


Beach grasses Ammophila arenaria Ammophila breviligulata Coastal barriers Ecomorphodynamics Foredunes Morphodynamics Oregon Pacific Northwest Sea-level rise Washington 



The field, mesocosm, and laboratory observations described in this manuscript are the result of the hard work by many individuals from Oregon State University, the Evergreen State College, the Washington Department of Ecology, the Oregon Department of Geology and Mineral Industries, and the U.S. Geological Survey. Funding for the work synthesized in this paper was provided by the U.S. Environmental Protection Agency (EPA/NCER 83383601-0), Oregon Sea Grant (NA060AR4170010, NA10OAR4170010), the National Science Foundation (IGERT NSF award 0333257), the National Oceanic and Atmospheric Administration (NOAA award NA15OAR4310243), the Northwest Association of Networked Ocean Observing Systems (NANOOS), the O.H. Hinsdale Wave Research Laboratory, and a Mamie Markham Research Grant (Hatfield Marine Science Center). This manuscript benefited greatly from thorough reviews of Evan B. Goldstein and an anonymous reviewer.


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Copyright information

© Springer International Publishing AG 2018

Authors and Affiliations

  • Peter Ruggiero
    • 1
  • Sally Hacker
    • 2
  • Eric Seabloom
    • 3
  • Phoebe Zarnetske
    • 4
    • 5
  1. 1.College of Earth, Ocean, and Atmospheric SciencesOregon State UniversityCorvallisUSA
  2. 2.Department of Integrative BiologyOregon State UniversityCorvallisUSA
  3. 3.Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulUSA
  4. 4.Department of Forestry, Fisheries and WildlifeMichigan State UniversityEast LansingUSA
  5. 5.Ecology, Evolutionary Biology, and Behavior ProgramMichigan State UniversityEast LansingUSA

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