The coastal dune ecosystems of northern California are home to many endemic plant species, including the Humboldt Bay wallflower (Erysimum menziesii Hook.) and beach layia (Layia carnosa Nutt.) which are federally and state listed endangered species. Over the last century, both of these endangered plants have been severely impacted by the introduction of the non-indigenous invasive plant species (NIPS) (Pickart and Sawyer, 1998) of European beachgrass (Ammophila arenaria (L.) Link.) and yellow bush lupine (Lupinus arboreus Sims.) (hereafter “beachgrass”, and “lupine”).
        Introduced to the Humboldt Bay region’s coastal dune ecosystems in the late 1800’s as part of a dune stabilization effort (Buell, 1992), NIPS have spread throughout the active dune mat habitat, interfering with ecological processes and altering dune morphology (Walter, 2010). Buell (1992) compared historical aerial photos to more recent satellite images and determined that between 1939 and 1989 beachgrass cover on the North Spit of Humboldt Bay had increased by 574%. In a more recent study, Walter (2010) found that beachgrass and lupine, along with other NIPS annual grasses, were responsible for nearly a 25% loss of active coastal dune habitat at the Humboldt Coastal Nature Center in Manilla, CA. The most visible loss of habitat was found in the active coastal dunes which once covered 32.4 ha (62.5% of the property) in 1948 and continuously declined to an area of 7.9 ha (15.23% of the property) in 2009 (Figure 1).

        As a result of the spread of NIPS, during the past 20 years’ dune ecosystem restoration and management efforts on the North Spit of Humboldt Bay have increased dramatically. In an attempt to restore dune diversity, non-profit organizations such as Friends of the Dunes (FOD) have made it their mission to eradicate NIPS from their coastal property for good. Community ecosystem restoration teams gather weekly to remove NIPS by hand. This type of restoration technique is important to note because it consists of vigorously pulling and digging the beachgrass and lupine out of the sand by the “rhizome,” beachgrasses’ reproductive underground stems. While hand pulling has proved effective in reducing the coverage of NIPS (Walter, 2010), the technique is extremely labor intensive and needs to be ongoing. Furthermore, at large spatial scales this technique may not be cost effective.
        Fire may also play a significant role in NIPS management. More than a century of anthropogenic disturbances has altered native plant diversity and subsequently the natural fire regime. Fire has the ability to increase the distribution and density of invasive plants by making new habitats available, increasing nutrient availability, and decreasing competition from other plants, which in turn decreases native plant diversity and species (Barrett, 2009). While naturally occurring wildfire is not common in the coastal areas of northern California, it is widely accepted by Native American researchers and members of the local Wiyot Tribe that fire was historically used as a management tool on the North Spit (Lightfoot et al., 2013).