Georgian Court University
What Plants Should I Plant Where on a Dune?
Vegetation plays a vital role in dune formation and stablilization. On windy days sand grains get picked up by the wind and blow around. When those airborne sand grains hit an object they stop blowing and fall to the ground. Thus the leaves of the beach grass and other plants on a dune act as collectors for blowing sand. Once on the ground, the grass blades help protect the sand from the breeze so the sand grains tend to stay where they land and start to pile up, forming a dune. As the plants grow they send out lots of roots and rhizomes that further trap and stabilize the sand, helping to make the dune stronger and more resistant to erosion. As a result, dune plants are a key component of an effective dune restoration plan.
‘Cape’ American beachgrass (Ammophila breviligulata ) is currently the species which is most often utilized in dune plantings in New Jersey and elsewhere in the US North East (Miller and Petersen 2006). Unfortunately, this species has very specific growth requirements and tends to thrive only in actively accreting dune regions (Seliskar 1994). After a few years, when the sand has become stabilized, the Ammophila breviligulata usually dies, yielding to other species that provide long-term dune coverage, if present, or leaving bare sand if no alternative "volunteer" species have colonized the area or been planted there in the interim. In response to this problem as well as the potentially negative effects of monoculture plantings on ecosystem resiliency and function, we suggest the following plan (Figure 1) for plantings in restored dunes.
Foredune areas (essentially from the dune crest seaward) should be replanted with "Cape" (using local varieties is important! Please don’t mail order beach grass from other states!) American beachgrass (Ammophila breviligulata ) culms in late winter to early spring, to maximize plant survivability and productivity. Culms should be planted in groups of two in a staggered pattern, approximately 24 inches apart, 7-9 inches deep, throughout designated planting area(s) with more highly spaced plantings toward the front of the dune, and denser plantings toward the back (Figure 1). If you are planting later in the season (past the dormant planting season), greenhouse produced plugs are a good alternative. These are more expensive than a bare root stem (culm) however they may be planted into early June
Secondary dune areas should be planted in late winter to early spring with a mix of grass and broad leaved ("forb") root stocks. Locally derived (genetically appropriate) clones of native dune grasses should be obtained from local nurseries. Plants suggested for use in this habitat include "Cape" American beachgrass (Ammophila breviligulata), "Avalon" saltmeadow cordgrass (Spartina patens), "Atlantic" coastal panicgrass (Panicum amarum var. amarulum ), 'Dune Crest" coastal little bluestem (Schizachyrium littorale ) , "Monarch Germplasm" seaside goldenrod (Solidago sempervirens) and beach pea (Lathyrus japonicus). (Picture credit nps.com)
If a denser cover is desired, these plantings can be supplemented with distribution of a local seed mixture of switchgrass (Panicum virgatum ) and coastal panicgrass (Panicum amarum var. amarulum ) salt marsh hay (Spartina patens), and coastal little bluestem (Schizachyrium scoparium ) at a seeding rate of approximately 12 lbs/acre.
Where rootstock are used, two culms should be planted per hole. Plants should be spaced 18" by 18" unless wind erosion is severe, then spacing should be reduced to 12" by 12". Plantings should be staggered in alternate rows to provide maximum erosion control.
In addition to plantings of grass and forbs, where there is suitable habitat (largely secondary and tertiary dunes), randomly distributed shrub clusters should also be planted about 25 feet apart from one another, as habitat features allow. Ideally, clusters should comprise of 3-6 shrubs planted within 5 feet of one another, and include species such as "Wildwood" northern bayberry (Morella pensylvanica ) and "Oceanview" beach plum (Prunus maritima ). (picture credit Jacqui Bonavito)
Once you have your plantings done, its important to install signage reminding people to "KEEP OFF THE DUNE" because dune plants are extremely sensitive to trampling and a few people walking over your newly planted dune can completely ruin all of your hard work!
Figure 1: Schematic of the planting scheme for an extended dune system
Click here for information on nurseries and other sources from which you can purchase local varieties of the plants listed here.
For more information on the plants listed here, visit the PLANTS Web site http://plants.usda.gov
Content of these pages was contributed by Chris Miller, Jon Miller, Michael Peek, Ray Bukowski, and Louise Wootton. Edited by Louise Wootton.