Retreat Blog

Dunes play an important role both to the beaches that front them and the land behind them. Dunes act as a sand reserve for beaches. Dune systems act as a buffer between the high energy of the ocean and the land. Dunes provide a barrier to salt intrusion from high tides and storm surges, and it protects the land behind the dunes from erosion.

The dunes in Florida are broken into five zones. These zones become more stable and are older as you move away from the beach. These zones are the pioneer dune zone, the fore dune zone, the dune field zone, the scrub zone, and the hammock zone.

The pioneer dune forms just above the highest tides. They are formed by windblown sand collecting around an obstruction. As organic matter is deposited by wind and waves, low herbs (e.g., sea-rockets, seaside evening-primrose) colonize the dune. As these plants collect more sand and organic matter, the dune increases in height becoming the fore dune.

As the fore dune grows it is colonized by sea-oats, railroad vine, sand spurs, beach croton, beach morning glory, and other plants. These low, tough plants have extensive root systems, which stabilize the dune.

Dune fields are formed as a series of older, stable fore dunes grow in height and organic content. The dune field will absorb much of the energy from storm surges, thereby protecting the land behind them.

When enough organic material has been collected, woody plants such as the palmetto, wax myrtle, cabbage palm, and sea grapes colonize the dunes. This creates a dense scrub zone. The oldest dunes may be colonized by trees such as the live oak and slash pine to create a maritime forest known as a hammock.