Ammophila arenaria (L.) Link

Rounded Global Status Rank: GNR - Not Yet Ranked

Reasons: Native to northwestern Europe and the British Isles; introduced to other continents to stabilize drifting sand. Established and locally abundant on dunes of the western U.S. coast.

Global Short Term Trend: Increase of 10 to >25%

Comments: Coastal sand dune systems around the world are threatened by the introduction and establishment of Ammophila arenaria. First, it is able to outcompete native dune plants. Second, it interferes with the natural dynamics of dune systems. In northern California, A. arenaria changes the geomorphology of the foredune community from a gentle slope to a vertical wall which prevents adequate sand movement from beach to interior dunes (Barbour and Johnson 1977). In Oregon, it has severely reduced the sand supply from beach to large inland dunes. Along the mid-Atlantic coast of the United States it is known to greatly alter beach profiles and subsequently change the impact and effect of storms on the coastline (Dolan et al. 1973).

The Northern Foredune Grassland Community described by Holland (1986) has been most severely threatened by the invasion of A. arenaria. This community is restricted to foredunes and is dominated by Elymus mollis. Only two undisturbed examples of this community remain in California, one of which occurs on the North Spit of Humboldt Bay (Holland 1986). The most pristine remaining occurrence is at the Lanphere-Christensen Dunes Preserve. In 1963, A. arenaria existed as one small clump 1 km north of the preserve boundary and as several clumps 4 km to the south. By 1984, it occupied 2.2 acres.

Management Requirements: Control of this introduced species is necessary to protect the limited occurrences of viable natural sand dune systems along our coastlines. Continued control of existing Ammophila arenaria stands and monitoring for new introductions are needed.

Manual removal (digging) controls the spread of A. arenaria but is labor intensive. In one case, complete removal was achieved, but the site was subsequently invaded by other exotic species. In the first year, monthly treatment intervals are suggested; in subsequent years, frequency can be decreased. Monitoring should be conducted to determine if exotic species, such as Carpobrotus, are replacing A. arenaria. Ultimately, re-vegetation with native species should be a standard part of management, once control techniques are refined.

Management Programs: Management of Ammophila arenaria is being carried out by TNC at the Lanphere-Christensen Dunes Preserve, by Humboldt State University through the Menzies' Wallflower Research Project, by the California Department of Parks at McKenicher State Park, at Vandenberg Air Force Base, and by the Oregon Department of Fish and Wildlife.

Contact: Andrea Pickart Habitat Restoration Coordinator Menzies' Wallflower Research Project Lanphere-Christensen Dunes Preserve 6800 Lanphere Road Arcata, CA 95521 (707) 822-6378.

James Barry Resource Protection Division California Dept. of Parks PO Box 2390 Sacramento, CA 95811 (916) 322-8562

Charles Bruce Oregon Dept. of Fish and Wildlife Route 5, Box 325 Corvallis, OR 97330 (503) 757-4186.

Monitoring Programs: The current monitoring program involves annual photodocumentation of stands before and after control treatments, and measurement of untreated stands.

Contact: Andrea Pickart, Preserve Manager Lanphere-Christensen Dunes Preserve 6800 Lanphere Road Arcata, CA 95521 (707) 822-6378.

Management Research Programs: The Habitat Restoration Program of the Menzies' Wallflower Research Project (MWRP) at Humboldt State University, Arcata, California, is currently investigating three methods of A. arenaria control: salt application, use of herbicides, and manual removal. Previous research at LCDP indicates manual removal (digging up plants 10 cm below the surface at repeated intervals) is effective in reducing stand density. An ongoing eradication program has utilized this method with mixed results. Complete eradication has been accomplished on only one stand. The MWRP is implementing an experimental program which increases the frequency and depth of digging to remove the active rhizome bud bank.

Earlier small-scale experiments at the preserve found that a 2% solution of Roundup, applied during anthesis, resulted in 60 to 100% mortality. The MWRP is further refining methods and specifications. Timing of application may be critical.

Salt was believed to be a potential control since A. arenaria has a relatively low tolerance to soil salt (NaCl), although brief to moderate exposure to high salinity may stimulate bud emergence (Baye 1988). Unfortunately, the use of NaCl to control a weedy species is illegal as it is not registered as a pesticide in the state of California. The use of alternate salts has not been addressed.

Management Research Needs: Research is needed on the effects of potential control methods including the use of herbicides (Roundup), manual removal, and salt application.