Sandy beaches and dunes along our coasts form a fragile and dynamic system. As the first lines of defense against the sea when storms hit, dunes act as flexible barriers to high tides and winds. Dunes may yield to storm winds and water, but the shifting mounds of sand will reappear in time.

As winds carry particles of sand across beaches, they are slowed by anything—a grass stem, a log, a piece of trash—and drop a portion of their load of sand. If the obstacle to the wind is a plant, the growth of the plant will keep up with the gradual accumulation of sand, and a small mound will form. The process continues until a sand dune covered by its community of grasses rests on the shore.

However, if sand is initially trapped by inanimate objects, the accumulation will be temporary, and the sand will eventually continue its wind-driven migration inland. Establishing a stable dune requires the constant sand-trapping of grass stems and leaves and the mat of roots to bind and hold the sand grains in place against the wind.

Natural recovery of damaged beaches and dunes is a slow process, and where damage is severe, as from hurricanes, it may be desirable to assist the natural processes to speed up the rebuilding.

Shoreline-property owners may consider a number of approaches to restoration. Some efforts have little or no costs other than work-hours expended, while others may be expensive in both money and time. Though all alternatives listed below are effective, combinations of two of more compatible techniques will give more rapid results. The results for each follow the listing.

Aid for Damaged Beaches and Dunes

Restrict traffic flow, pedestrian and vehicular, over damaged area to

allow maximum recovery of remaining vegetation.

Fertilize remaining vegetation and seedlings to enhance regrowth.

Erect barriers to promote sand accumulation by the use of brush fences or slat fences.

Revegetate damaged area with purchased plants or transplants from surviving vegetation.

Restricting Traffic

All efforts should be made to protect struggling plants from the additional damage of traffic through disturbed areas. Where crossing the dunes is necessary, temporary boardwalks may minimize any damage. However, this is effective only if the walks are used. Public awareness is the best approach to reduce traffic damage.

Fertilization

Fertilizers should only be used sparingly in beach and dune areas because excess nutrients may alter development and diversity of coastal plant communities. Suggested rates and timing of fertilization for dune areas should also take into account the sandy nature of the soil. Since most sands are infertile, the addition of fertilizer will increase plant growth and result in a denser cover in shorter period of time.

However, soluble fertilizer nutrients, such as nitrogen, will quickly wash or leach through the soil profile away from the reach of the plants into the groundwater. Managers should utilize a strategy of applying a less soluble, slow-release form of nitrogen or apply a soluble fertilizer more frequently but in smaller quantities.

Regardless of the release rate or solubility of the fertilizer, the maximum annual application of nitrogen should not exceed 150 to 200 pounds of nitrogen per acre and phosphorus should not exceed 50 to 60 pounds P2O5 per acre. These values convert to about 3.5 to 4.5 pounds of nitrogen per 1,000 square feet and 1.0 to 1.5 pounds P2O5 per 1,000 square feet. Since the sandy soils cannot retain the nitrogen fertilizer, this annual application should be split into three to four equal applications of no more than 1.0 lb

N/1000 sq. ft. per application when using a soluble fertilizer. Fertilizer with a ratio of 3 parts N to 1 part P2O5 is ideal, but many fertilizer materials can be used to supply these rates. These maximum applications rates will allow a greater efficiency in the use of fertilizer nutrients since sandy beach soils do not have the ability to store them.

Slow-release Fertilizer

Newly planted Sea Oats may be fertilized with a slow-release fertilizer product at the time of planting. Apply a complete (N-P-K) fertilizer which contains a slow-release nitrogen (e.g., 16-4-8 or 15-4-15) to provide up to 4.5 pounds of actual nitrogen per 1000 square feet.

Look for the words slow-release or controlled-release on the fertilizer labels. Nitrogen in this type of fertilizer will not burn or wash away as readily as quick-release (soluble) nitrogen sources.

Soluble Fertilizer

A complete fertilizer with a soluble source of nitrogen may be applied about two weeks after planting. A complete fertilizer such as 8-8-8 or 16-8-8, with the nitrogen in a soluble form (ammonium sulfate, ammonium nitrate, sodium nitrate or urea) should not be applied at more than 50 pounds of nitrogen per acre (1.0 lb N/1000 sq. ft.) per application.

Sand Fences

Sand fences may be erected to trap and accumulate sand. Fences should be placed crosswise to the winds carrying the sand. In general, a fence parallel to the shoreline is most effective. If sufficient funds are available, two lines of fencing, 15 to 20 feet apart, are effective. Fence lines should be well above high water to prevent wave destruction and far enough back on the upper beach so that winds can move an adequate supply of sand inland (a minimum of 200 feet is recommended). Care should be taken in locating fences to avoid burying existing plants. Fences should not be so high that sand accumulates more rapidly than the growth rates of beach plants, thus burying them (maximum of five feet).

Brush Fences

Brush piled or spread loosely will effectively trap sand. Furthermore, little sand is lost from these piles as the wind shifts direction. For extensive use, brush must be readily available in large quantities at a reasonable cost.

Brush will collect more sand if placed in a standing position. Dig a trench 1½ feet deep and 6 inches wide. Place the butt end in the trench and firmly pack sand around it. To increase the stability of the brush in the upright position, fence posts with boards between them are often needed to support the

brush. Posts spaced 8 to 20 feet apart will probably hold up the fence.

Discarded Christmas trees make good fences but availability is seasonal. Local shrubs, such as willow and wax myrtle, may take root, therefore they should be used if available.

Brush fences are unsightly until buried and may be damaged by picnickers seeking firewood. However, they are as effective as slat fences, and much more economical.

Slat Fences

Slatted fencing, such as commercial snow fence, is superior to solid materials for collecting sand. On the beach, 4-inch slats, 2 to 3 inches apart are typical. Anchor posts spaced 8 to 10 feet apart should be set 3 to 4 feet deep in the sand to withstand the winds and the weight of accumulating sand.

Where large amounts of sand blow about, fencing is buried quickly and additional fences may be erected to make the dune higher. Placing brush at the base of the fence will hasten sand trapping.

Revegetation

Fences, brush and other non-living barriers are only temporary measures used to stabilize sand. When they become buried, the sand moves on. Vegetation has proven more effective. Salt- and sand-resistant grasses grow upward through fresh sand deposits and spread laterally, forming a dense cover. Lateral growth, above-ground by stolons and below-ground by rhizomes, helps stop sand removal.

To grow well at the ocean shore, a plant must be able to tolerate up to several feet of sand accumulation per year, sand blast strong enough to take the paint off a car, salt spray, salt-water flooding, drought, heat and low nutrient supply. Those species occurring naturally in an area are usually best adapted to local conditions and should be utilized where possible. However, in badly damaged areas, plants of native species should be obtained from nurseries before thinning natural stands.

Planting Guidelines

To be successful, plant where a dune would most likely occur in nature—in the path of blowing sand parallel to the high-tide line. Start dune plantings as far as possible from the water since the dunes grow toward the sand supply, which is usually the surf zone. Several hundred feet from the high-tide line isbest. Whenever feasible, leave room for 2 or more dune lines—a double line of protection. A grass planting 40 to 50 feet wide can trap several cubic yards of blowing sand per foot of beach in a year.

Space mounds 18" apart on all sides, one plant per mound (1000 plants per 50x100 feet area)

Small areas and steep slopes should be planted by hand by setting plants into individual holes

made with a shovel or dibble. Pack sand firmly around each plant. Larger and smoother sites can be planted more economically with tractor-drawn transplanters.

A mixed planting with more than one species will usually provide better results in terms of

disease and pest resistance, survival and coverage rates.

Taking transplant material from damaged areas should be done with great care, and only if

necessary. Leave at least half of the original material. Younger plants transplant better than older, longer-rooted plants. Wrap roots with moist dirt in burlap or newspaper. Transplant as quickly as

possible.

Graduated planting with greater spacing (up to 4 feet apart) around the edges allows sands to get to the middle of the planting and build a wide dune area.

A sand fence in the middle of the planting area will help collect sand for the first 6 months while the plants get started.

Fertilizer may be applied to transplants as an additional aid to successful plant establishment.

During the first year, 3 or 4 equal applications (not to exceed 200 pounds of Nitrogen per acre)

should be applied during the spring and summer. In the second year, reduce to two to three applications (not to exceed 150 pounds of Nitrogen per acre) with a single application the third year (not to exceed 50 pounds of Nitrogen per acre). Fertilizers should only be used sparingly in the beachand dune areas because excess nutrients may alter development and diversity of coastal plant communities.