As climate change leads to sea level rise and increases in the frequency and intensity of storm events, coastal dunes serve as the “first line of defense” against flooding and provide key ecosystem services, such as conserving biodiversity. In the Pacific Northwest, sand dunes have undergone a transformation beginning in the early 20th century with the introduction of two invasive beachgrasses, European beachgrass (Ammophila arenaria) and American beachgrass (A. breviligulata). Although these invasive grasses build dunes that protect coastal communities from storms, their spread has also led to the decline of native dune species, posing management tradeoffs.

In 2012, a novel beachgrass hybrid, the offspring of European and American beachgrass, was discovered by Dr. Sally Hacker’s research group at Oregon State University. Since then, over 60 hybrid patches have been detected, covering more than 250 km of coastline in northern Oregon and southern Washington. The height, density and growth form of the beachgrass hybrid will determine the volume of sand it traps, the shape of dunes it forms and thus the level of protection the hybrid may provide against storms and sea level rise. Similarly, if the hybrid’s spread and growth are similar to that of its parents, further declines of native dune species may occur.  

This research seeks to determine how the hybrid’s density, growth form and sand capture ability, as well as the shape of dunes it produces, differ from that of its parents, and how these differences may affect dune biodiversity and coastal protection. These results will be used by resource managers, including Oregon Parks and Recreation Department and Oregon Department of Land Conservation and Development, to understand impacts of this hybrid and to develop management plans that maximize ecosystem services like biodiversity while minimizing flooding risk.