Sand Dune Ecology

The continuous sculpting of our beaches is an amazing thing. Every morning it seems, the slope, aspect and texture of the beach is new. While we sleep, the action of wind and wave does this renovation. But above the high tide line, we have a very important phenomenon; the sand dune. Dunes are our best defense against the sea and it is vital to maintain their integrity. According to Frank Herbert, Dune Ecologist, “dunes are mounds of sand that have been piled by the action of winds. The sand is usually composed of bits of minerals that have been eroded from rocks, picked up by water or winds, and then re-deposited somewhere else. Typically, the sand is deposited behind some object that is a barrier to the movement of air currents, which causes the wind speed to slow suddenly so that the load of sand particles can no longer be contained against the force of gravity, and it falls to the ground.”

After a mound of sand forms some highly adapted vegetation forms can take hold. The pioneering plants are physiologically adapted to high salt content in the air and soil, and are good examples of stress tolerators. It is the active vertical growth of these plant species that allows the vegetation to keep above the building dune while buried roots and plant parts serve to stabilize the dune as it grows.

During a storm, these well anchored dunes will help diffuse the force of the storm surge and will protect the areas behind them. But dunes are very vulnerable to mechanical disturbance. A single ATV tire track can destabilise the dune and disrupt the delicate ecological balance.

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