Why do people plant marram grass on sand dunes?

Marram is a tough perennial grass that is often planted in shifting sand dunes to help stabilize them. Between the edge of the water and the beginning of the dunes, dry sand is constantly shifting and floating. One of the few plants that can take root in this windy environment is marram grass. It spreads its tuberous roots just under the surface of the sand, and forms an underground web that helps hold the sand in place. This allows the soil to stabilize and the dune to grow higher.