INTRODUCTION

A Dune revegetation program is currently under way for the dune along the Municipal Beach. Part of that dune, from the dune crest west to the west toe of the dune, is in need of revegetation. The main plant type, beachberry (Scaevola frutescens) is no longer an acceptable species. In addition, the area has experienced plant losses due to disease, leaving bare patches. A plan and program has be developed to replace the beachberry with a diversity of scrub zone species.

Beach dunes and vegetation are part of the overall erosion control mechanism on the coast. Sand which forms the dune is trapped by vegetation; dunes provide a source of sand to act as a buffer to storm-driven erosion. The system acts as a shock absorber to protect upland property from storm damage.

In addition to their role in erosion control, coastal vegetation provides natural beauty and habitat for coastal animals. In Delray Beach, vegetation can aid the survival of sea turtles by partially screening artificial lights creating the background glow of the City.

Pristine dune vegetation is roughly divided into zones of habitat. From seaward to landward, these are:

• Pioneer Zone - seaward of the dune crest, dominated by grasses such as sea oats, and vines.
• Scrub Zone - on the landward side of the dune, made up of salt-tolerant shrubs and small trees.
• Forest Zone - upland of the dune, consisting of hardwood trees and pines.

In Delray Beach, only the pioneer and scrub zones are represented.

PROJECT HISTORY

Prior to 1973, no dune existed along the Municipal Beach. Erosion had destroyed both the dune and beach, offering little storm protection and only a marginal recreation beach.

In 1973, the City constructed an initial beach restoration. Nourishment projects in 1978, 1984 and 1992 have maintained this beach to provide both storm protection and recreation.

The City began a program of dune reconstruction and maintenance in 1974. Using vegetation consisting of beachberry (Scaevola frutescens) and sand fencing, several feet of wind-blown sand were trapped to form the beginnings of a dune. Over the next several years the dune continued to grow and kept most of the sand from blowing onto the sidewalk.

Two improvements were constructed in 1980. Additional vegetation, including beachberry and seagrape (Cocoloba unifera) were planted to angle pedestrian access points to the southeast. This further reduced the amount of wind-blown sand reaching the sidewalk. In addition, two rows of sand fence were placed seaward of the dune to create a foredune and slow accretion of the primary dune.

In 1982, sea oats (Uniola paniculata) were planted between the sand fences and original dune. The sea oats have been successful in expanding the foredune. Sand fences and sea oats have also kept foot traffic to a minimum in the dune area, allowing many species of native vegetation to grow.

EXISTING CONDITIONS

The pioneer zone seaward of the dune is dominated by sea oats with a large variety of native vines and grasses. Sea grapes are largely confined to the pedestrian access points.

The dune crest and back dune are dominated by beachberry, an ornamental species now considered an invasive exotic. In recent years, the beachberry has suffered from a root virus and stress due to cold weather. Where plantings have died out, they have been replaced with sea oats and Pittosporum tobia. Upland species, especially weeds, have invaded stressed areas.

PROPOSED REVEGETATION PROGRAM

The proposed revegetation program would, over time, replace the beachberry and other exotics with a variety of native dune species. The project area is from the crest of the dune west to the west toe of the dune, and from Casaurina Road to the north end of the Municipal Beach. Revegetation is ongoing over an extended period of time so that the dune will never exhibit a bare look or become unstable.

Parameters or the program will be as follows:

• Dune plantings will replicate the pioneer and scrub zones of a pristine dune. This will require a broad diversity of species to be installed.
• All plantings in the dune area will be native to the pioneer and scrub zones.
• Species selected will be low maintenance and require no irrigation.
• Invasive exotics, as listed in the Coastal Protection Ordinance (#34-90) will be removed from the pioneer and scrub zones. Planting and pruning practices will be in accordance with the guidelines in the Ordinance.
• Dune vegetation will seek to provide view lines to the ocean and partial screening of artificial lighting to protect sea turtles. This can be accomplished by alternating areas of lower and higher growing species to produce an undulating canopy along the dune crest.
• In the pioneer zone, little work is needed. It is sufficient to remove invasive exotics and fill any sparse areas with native species.
• Replanting in the scrub zone will be accomplished using subcontracted forces, working over an extended period of time. This will allow work to be completed without disturbing dune stability or aesthetics - a large extent of bare dune will not be allowed.

A demonstration section of the project was completed by the Parks and Recreation Department opposite the pavilion at Atlantic Avenue along with a second phase near the north pavilion. The rest of the project will be completed for a total cost of $120,000, two thirds of which will be reimbursed by the State under a grant agreement.

Keep an eye out for the changes to the dune as you stroll the beachfront. Or beautiful beach and dune will be getting even better.