NATIONAL PARK SERVICE Research in the Parks NPS Symposium Series No. 1

ABSTRACT

In its recently assumed role of custodian of national seashore recreation areas, the National Park Service is under pressure to: (1) maintain unspoiled lands within reach of the major cities; and (2) control shoreline retreat. Each of these demands implies a need for a different policy. National Park Service managers thus are forced to try to reconcile conflicting demands and philosophies, often without hard data on which to base their decisions. Past studies of coastal ecosystems often have been so compartmentalized that the overall picture is not seen. It may be hard to determine what the "natural" ecological conditions of an area were in the past, and even when these conditions are known, it may not be practical to restore them. Attempts in this direction, in the form of erosion control or reforestation, sometimes have destroyed an existing "natural" ecology better adapted to today's conditions.

In their natural state, barrier island landforms are the result of, not the victim of, the oceanic environment. Having arisen from breached spits, engulfed dune ridges, or a combination of the two, the beaches undergo short-term cyclic changes in width, as well as longer-term retreat and rearrangement due to overwash, erosion, and the opening and closing of inlets. It is only by retreating that the islands are able to survive in the face of rising sea level. The island biota is uniquely adapted to stress in the form of storms, overwash, salt spray, and sand movement. In particular, certain grasses serve to absorb the energy of overwash water, trapping and growing up through the water-borne sand, thus keeping the island elevation and their own habitat above sea level. Even though the Cape Lookout National Seashore islands show a history of sweeping changes, evidence from old maps and records and from island stratigraphy indicates that they have maintained the same ecosystems and general appearance for hundreds of years. Such "dynamic stability" is the true natural state of barrier islands, but the processes that maintain it have been suppressed on managed strands. Total artificial control of a coastline, therefore, is recognized increasingly as physically and economically impractical.

In seeking a solution to the management dilemma, the relatively undisturbed islands of Cape Lookout National Seashore are here compared with the altered Cape Hatteras strand. The major ecosystems of the undeveloped islands are the beach and berm, maritime grasslands, woodlands, fresh marshes, and salt marshes; their vegetation, zonation, and succession are described and related to island dynamics. The most productive salt marshes are those that have grown up on recent overwash fans or on the flood tidal deltas of newly closed inlets. Maritime woodlands turn out to be transitory features, representing the natural vegetation of only the most protected sites; grasslands are far better adapted to oceanic stress. Ecological changes arising from attempts to stabilize these natural systems are discussed. It is suggested that a high, continuous, artificial dune designed to prevent overwash may actually exacerbate erosion of the foreshore, while preventing the build-up of the island's interior and the extension into the sound of the backshore salt marshes. Thus, islands held in one place become lower and narrower and inherently less stable.

Original settlers of the Outer Banks affected the natural vegetation by cutting wood and grazing livestock. Overgrazing may have encouraged sand movement in some cases, but the overall appearance of the undeveloped islands is due to natural forces rather than to the activities of early settlers.

By leveling dunes and interfering with natural island dynamics, modern man has increased the islands' susceptibility to storm damage. Temporary engineering solutions nearly always make the situation worse. Salt-water intrusion into the fresh-water lens, ill-advised dredging operations, off-road vehicle use, and the introduction of litter and derelict cars are further ecological and aesthetic problems accompanying modern use of barrier islands.

It is suggested that ideal management of these areas should avoid attempts to hold back the ocean or stabilize the land. Development should be minimal and should be located so as not to require extensive protection. The natural dynamics of sand and vegetation should function unimpeded; where grass planting and dune building are deemed necessary, they should mimic the natural pattern. Of course, allowing natural processes complete freedom on already developed islands is no more realistic than are continued attempts at total engineering protection of roads and buildings against rising sea level. Rather, a middle course, sensitively orchestrated for a different area, is indicated. Roadless, bridgeless islands should remain so; all recreation should proceed with a view to preserving, not degrading, the resource. Wilderness areas should be set aside on the islands to serve as controls against which human impact on the rest of the system may be monitored.