Footprints in the Sand - Eco Trail
Please leave only your footprints

Dunes – Shaped by
Wind and Vegetation

Dunes form when waves encourage the accumulation of sand and prevailing onshore winds blow this sand inland. Obstacles such as vegetation or pebbles trap the moving sand, causing it to accumulate and form a dune. Over time, various forms of vegetation, such as grasses, shrubs, and small trees, take root in the dune and help to mold and fortify its structure.

Dunes are critical in the overall ecology of the island. If a primary dune field (those closest to the water) is removed or damaged, then the wind and salt spray will more easily reach the secondary dunes where plant and animal life is unaccustomed to such harsh conditions. The result is a domino effect that can severely harm a number of species. The loss of dune fields can also increase the overall movement of the island and cause erosion. Walking over the dunes will increase the rate of their erosion and, thus, that of the island itself. Please help preserve the dunes by using boardwalks when walking to the beach!

Types of Dunes

Dunes can be divided into three categories: primary, secondary, and tertiary. The primary dunes are those closest to the Gulf. They are dominated by grasses such as sea oats and switchgrass that are flexible in the strong winds and tolerant of the salt spray off of the ocean. Behind the primary dunes, the wind and salt decrease enough where small, round shrubs and bushes can establish themselves, forming secondary dunes. Landward of the secondary dunes are the tertiary dunes, where the wind and salt spray have diminished even more. Here, trees such as live oak and yaupon holly can grow, trapping a tremendous amount of sand forming some of the most impressive dunes on the island; some are more than 50 feet high.

Sea Oats

One of the most common plants you’ll see growing in our dunes is the sea oat. Sea oats are important to barrier island ecology and are often used in soil stabilization projects because their long root structure firmly holds loose soil. Sea oats also help protect the mainland against hurricanes by providing a stronger barrier against the surging tide. Picking or disturbing sea oats is punishable by fine.

Switchgrass

Switchgrass, also known as panic grass, makes its home in our dunes. It plays an important role in erosion control. In other ecosystems, it is used as feed for cattle and other grazing animals. Due to its ability to produce high yields on low-quality farmland, switchgrass has been researched as a bioenergy crop for a number of years. Some, including President George W. Bush, have suggested using switchgrass as a component of ethanol fuels in place of more expensive crops such as corn.

Dune Restoration

Dunes play a vital role in preserving the ecosystem of Pensacola Beach as well as the mainland. Unfortunately, the health of the local dune system is threatened by erosion, hurricanes, land development, and human interference. The one-two punch of Hurricane Ivan and the Deepwater Horizon oil spill, which both caused extensive dune damage, has resulted in dune conservation becoming a top priority for Pensacola Beach.

Dune conservation primarily consists of two methods: fence construction and vegetation planting. Fences are placed behind the dunes, preventing sand from blowing further inland and forcing it to accumulate, thus building up the dune. The vegetation integrates with the dune’s existing root system, strengthening the dune’s frame and helping to hold more sand in place.

There are things you can do to help conserve dunes as well. Always use public crossovers—don’t walk, sit, or play on the dunes. Keep your trash and debris away from dunes. And tell others about the importance of dune conservation. Together, we can keep our dunes healthy for years to come.

Restoring Vegetation

Planting dune vegetation is not as easy as it sounds. Merely scattering seeds over sandy areas is perceived as a potential waste as strong winds can blow seeds away. Planting of nurseries should be conducted in the hollows of any present sand hills or in depressions of sandy areas. Seeds should be planted in moist conditions and should be lightly covered by a layer of sand. Large mature grass should be planted in deep holes with the tops of the plants cut short to reduce wind resistance.

Invasive Plants

Human introduction of invasive plants to dune environments has also spurred the need for dune conservation. European beachgrass, iceplant, and yellow bush lupine have all been known to impede dune growth. Once introduced, these plants must be manually removed in order to heal the dune.