Examining Coastal Resiliency in Restored Foredunes, Humboldt Bay, California

Abstract

Coastal communities are under increasing pressure because of sea level rise, storm surges, coastal flooding, and anthropogenic climate change. The coastline of Humboldt County, California, experiences the fastest rates of sea level rise in California. Coastal foredunes provide protection to these communities, but erosion and invasive vegetation threaten their ability to protect inland communities. This research aims to better understand the impact of invasive versus native plant assemblages, in areas that have been dynamically restored. This project employed a series of 73 cross-shore profiles, monitored biannually from 2016-20, that extended from the water line to some distance (typically ~50-150 m) inland of the foredune crest. A team of trained analysts identified features of interest along each transect (n = 828). This study examines 15 of the 73 transects that have been restored. Initial results show that restored and natively vegetated dunes trap more sand, create more robust backdunes, and retain more sand annually than their invasively vegetated counterparts. The promise that native assemblages bring promotes increased resiliency of dune barrier systems and security for critical coastal communities. This study will help inform the stakeholders of Humboldt Bay where attention is necessary and if restoration efforts are proving effective.