Carolina Environmental Diversity Explorations

The northern Outer Banks · By Dirk Frankenberg and Blair Tormey

How Vegetation Acts as a Natural Protective Barrier

Figure 12. A partially eroded portion of the primary palisade dune at Coquina Beach, which is protected by its vegetation. (Photograph by Blair Tormey. More about the photograph)

Vegetation on the dunes at Coquina Beach plays a crucial role in their ability to protect the island from storm overwash. Close inspection of the partially eroded primary dune offers a unique view of the anastomosing pattern of rhizomes that help to stabilize the dune. Rhizome forms are an effective adaptation to the rapid burial typical of dune environments. Because they do not depend on seed dispersal for reproductioon, species such as Spartina patens, sea oats, and American beach grass are able to recover quickly from storm erosion and thus stabilize the dune.

Definitions

overwash n.
The transport of sediment landward of the active beach by coastal flooding during a tsunami, hurricane, or other event with extreme waves.
dune n.
A hill or ridge of wind-blown sand.
anastomosing adj.
Interlacing or running together, for example, like the veins on a leaf.
rhizome n.
A horizontal, usually underground stem that often sends out roots and shoots from its nodes (a knot or bulge on the plant root or shoot). Buds that form at the joints produce new shoots and can become new plants; also called rootstalk or rootstock.