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Restore natural coastal buffers: Native vegetation buffers and plantings
Adaptation Strategies and Actions
Restore natural coastal buffers: Native vegetation buffers and plantings
Enhance habitat value and reduce erosion of dune nourishment and coastal bank stabilization projects.
Vegetated buffers are strips of grasses, shrubs, and other plants (other than lawn). These buffers absorb stormwater, slow its overland flow, and break the direct impact of raindrops or wave splash. The plant roots also bind and secure soils and help improve the stability of the area. Using native coastal plants (including shrubs, groundcovers, and grasses) preserves the natural character of the coastal environment, helps to filter pollution, and provides habitat for wildlife.
Incorporate native vegetation in restoration efforts of coastal landforms susceptible to erosion from tides, currents, wind, and coastal storms.
The coastline can be an inhospitable place for many plant species; these highly dynamic areas regularly experience wind and wave action, and salt spray from the ocean. The sandy soils are also low in nutrients and can be very hot and dry. However, there are plants that are well adapted to these conditions – with characteristics that make them fit to survive the elements. Plants that are resilient to harsh coastal conditions are one of the best remedies against the forces that cause erosion and destabilization of dunes, banks, and bluffs along the coast.
How vegetation buffers reduce overland runoff, erosion and storm damage
Plant roots hold sediment in place, helping to stabilize the areas where they are planted. By absorbing water, plants reduce erosion caused by runoff. They also break the impact of raindrops or wave-splash, and physically slow and disperse the speed of water flow from storm surge. Vegetation also helps trap windblown sand, which is particularly important for building dune volume, increasing the dune’s ability to buffer inland areas from storm waves, erosion, and flooding. The stability of coastal banks that are made of loose materials – such as sand, rocks, or soils – can be greatly improved by plants. A strip of dense shrubs, perennials, and/or deep grasses along the top of a coastal bank can also limit access and foot traffic that may otherwise aggravate erosion and/or disturb habitat.
Overland runoff and how it causes coastal erosion
Channels or gullies on the face of a bank or dune are a sign of a runoff problem. Runoff causes erosion when water falling on and/or running across bare or sparsely vegetated areas dislodges vegetation, soil, sand, and other sediments. Controlling runoff from upland sources helps reduce a significant cause of erosion on many beaches, dunes, and banks. Efforts to control runoff focus on reducing the quantity and velocity of water flowing across the land surface and changing the direction of flow as necessary to address specific erosion problems. If overland sources of runoff are not successfully managed, the effectiveness of shoreline stabilization techniques can be compromised. When runoff flows over a coastal bank, dune or beach, it can erode these landforms from above and worsen other coastal erosion problems (i.e., erosion from tides, currents, wind, and coastal storms). Salt-tolerant plants with extensive root systems can help address both kinds of coastal erosion problems.
General design considerations
Choosing an appropriate location
Vegetation projects for erosion control are appropriate on virtually any dune or bank along the coast where sand and other sediments are exposed to wind and waves. However, the longevity and effectiveness of these projects to provide erosion control can be limited in certain locations; additional techniques, such as the use of natural fiber coir blankets and rolls may be needed in addition to using vegetation for reducing erosion and stabilizing an area. Projects seeking to create or restore vegetated buffers would ideally plan for a minimum of five to ten feet in width landward of the top of the bank, dune, or beach targeted for protection.
Native grasses that are extremely tolerant of salt spray and exposure to wind and waves, such as American beachgrass, can help build up windblown sediments on the face of banks or bluffs and effectively bind the soil with their thick, fibrous root systems. The roots of beachgrass can establish themselves quickly, while allowing other plants to take hold. The roots of plants such as dustymiller, beachpea, and seaside goldenrod act like “glue” that holds the dune together.
Beyond dune vegetation, some of the most effective plants for vegetated buffers in coastal areas include:
- Beach plum
- Virginia rose or Carolina rose
- Arrowwood viburnum
- Sweet fern
A more comprehensive list of appropriate native plant species can be found on the StormSmart Coasts Coastal Landscaping in Massachusetts webpage.
Minimizing impacts to wildlife
In general, the impacts of vegetation projects are relatively minor when compared to other stabilization options (such as the use of hard structures). Vegetation projects in habitat for protected species, however, do have the potential to cause unintended and significant impacts, such as removing open sand areas needed for successful nesting of piping plovers and diamond backed terrapins. Even the planting of native plant species can cause unintended harm in these areas. Because vegetation can alter habitat, care must be taken with vegetation projects in protected species habitat and consultation with fish and wildlife managers, such as the Massachusetts Natural Heritage and Endangered Species Program, is advised. Selecting appropriate types of vegetation (e.g., grass vs. shrubs) and increasing the spacing between plantings can reduce impacts to nesting habitat for protected shorebirds and turtles.
- Select appropriate species for site conditions.
- Plant at the appropriate time of year (generally spring or fall), and follow the specific instructions for watering, fertilizing, and general care and maintenance.
- Plant trees far enough back from the top of coastal banks to ensure that their weight does not contribute to bank instability. If trees on or near the bank are leaning, they may increase instability of the bank and may need to be pruned or removed.
- Do not place dead plant material, such as lawn clipping, brush, and discarded Christmas trees, on a bank or other coastal area. These dead plant materials limit the natural growth and establishment of plants and do not have roots that help bind soils together.
- Fertilizer can cause nuisance plant or algae growth that can degrade water quality. Nitrogen in fertilizer is a particular problem in coastal waters. Consequently, the use of fertilizer on vegetated buffers, as in all coastal areas, should be limited as much as possible. When designed and maintained correctly, vegetated buffers will actually filter out nitrogen and other contaminants from inland sources, helping to reduce coastal water contamination.
- When selecting plants, avoid the use of invasive species. Because certain native plants thrive in coastal conditions, they may also out compete and control unwanted invasive species, such as multiflora rose, oriental bittersweet, and Japanese knotweed – all of which tend to take over and require a lot of maintenance and weeding to keep a tidy appearance.
Target Species, Species Groups, Habitats and Stressors
Scope and Constraints
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