Dynamic restoration and the impact of invasive vegetation on coastal foredune resilience: Seven years of change at the Lanphere Dunes, CA, USA
Topics:
Keywords: close range remote sensing, coastal, aeolian, coastal erosion, ecomorphodynamics, geomorphic change detection
Abstract Type: Paper Abstract
Authors:
Zach Hilgendorf, University of Wisconsin-Eau Claire
Ian J Walker, University of California-Santa Barbara
Andrea J Pickart, United States Fish and Wildlife Service
,
,
,
,
,
,
,
Abstract
The Lanphere Dunes, within the Humboldt Bay National Wildlife Refuge in northern California, has been the focus of foredune restoration efforts since the 1980s. Efforts have centered around removal of an invasive European beach grass species, Ammophila arenaria, introduced ca. 1900 to stabilize dunes, restrict sediment transport, and protect landward communities from coastal flooding and storm surges. Despite effectively stabilizing the foredune, A. arenaria forms monotypic stands, with dense, rhizomatous roots and above-ground biomass that can lead to pronounced scarping of the seaward slope, alongshore steering of wind and sediment, a lack of landward sand transport, and a steeper, peaked profile.
A 5 ha reach of restored foredune was monitored biannually with terrestrial laser scanner and uncrewed aerial platforms between 2015 and 2022 to characterize the impacts of dynamic restoration on foredune form and resiliency. This reach included two control plots: (1) native, non-restored and (2) invasive, and three restored plots revegetated with native species: (3) native grass (Elymus mollis), (4) a low-lying herb and subshrub assemblage, and (5) a mixture of both native assemblages.
After six growing seasons, restored plots exhibited distinct geomorphic and sediment budget differences. Natively vegetated plots recovered from extensive scarping 2 years faster than the invasive plot. Restored plots saw foredune height and width increase, minor progradation, and positive sediment budgets that exceeded both control plots. These results suggest that natively vegetated plots allowed increased landward sand transport across the foredune, and increased the capacity of the foredune to recover more quickly following dune scarping
Dynamic restoration and the impact of invasive vegetation on coastal foredune resilience: Seven years of change at the Lanphere Dunes, CA, USA
Category
Paper Abstract