How Sand Dunes Work

You'd think a pile of sand could never support a thriving ecosystem. But sand dunes host countless numbers of organisms. From sweet-smelling flowers to small rodents, many living things have adapted to a life in the sand. Dune vegetation pays back the favor by protecting the dunes from damage.

Obviously, desert and dune plants must be drought-tolerant. Some plants store rainwater in their leaves and stems, while other plants have long root systems that burrow down to the water table. The long roots tend to stabilize and anchor the dunes, preventing them from eroding during a storm. Some of the plants and flowers that grow in sand dunes include: pink sand verbena, white dune evening primrose and yellow sunflower. Shrubs are also well suited for dune life, and many animals rely on bushes like mesquite, creosote bush and desert buckwheat for shade and shelter.

Sand snakes and lizards also call sand dunes home. These reptiles burrow rapidly through the sand, an action known as sand swimming. Hundreds or even thousands of types of insects also make their habitats in sand dunes. Beetles, moths, wasps, flies, crickets and spiders all live in the sand. Many of these insects prey on each other as well as feed on dune vegetation. Certain rodents also can live in sand dunes and create complicated burrows within the dunes, emerging to feed on the seeds and leaves of dune plants.

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Vegetation on coastal dunes is particularly important because it helps to anchor the dunes and protect them from damage and erosion. The most common vegetation you'll see on coastal dunes is dune grass. Dune grass grows in the sand, requires full sun and can withstand salt spray. The grass has long, flexible stems that help it to withstand forceful winds. Powerful sprawling root systems help anchor it in the sand and also protect the dune from erosion. Sea turtles are also important to coastal sand dunes. Many turtles nest in the sand, and their eggs provide valuable nutrients for dune vegetation.

Because these fragile ecosystems are all dependent on each other, it's important to protect sand dunes. Beaches and sand dunes need each other -- beaches need the dune's sand reservoirs in order to replenish after a storm, and dunes need the beach's sand to form in the first place. Coastal sand dunes suffer from erosion during storms and hurricanes and when humans interfere. Deforestation also contributes to sand dune erosion because loss of vegetation makes the dunes unstable. As sand dunes lose sand -- perhaps from waves reaching them during a particularly strong storm, or because humans disturb their structure -- they also lose their ability to absorb storm surges. Dunes can take decades to recover from this sort of destruction [source: CSI].

The reason you see "Stay Off the Dunes" signs at the beach or lake is because walking around on the dunes can damage the vegetation. And, as we've learned, the long root systems of dune vegetation help to keep the dunes anchored and stable.

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