The characteristic zones of parabolic dunes are the beach, foredune, interdunal wetland or trough, and the backdune, each with its distinctive physical character and biota.
The beach is the most dynamic zone, where wind, waves, and coastal currents create an ever changing environment. Wind velocity is highest at the shoreline, as is the frequency of flooding and the wave energy. Because of these extremes, few plants and animals are adapted to live on the beach.
The foredune is the zone where pioneering grasses cause sand to begin accumulating. It can consist of a distinctive, low dune feature, or merely a low landward continuation of the beach. Not only must plants of the foredune tolerate periodic burial, they must also survive extreme tempera-tures, low moisture levels, and low levels of nutrients. Extreme temperatures cause many of this zone’s inhabitants, such as Fowler’s toad, the eastern hognose snake, and spider wasps to burrow during the day to reach cooler temperatures.
Behind the protective foredune, winds are lighter and sand accumulation is slower, allowing trees to establish and form forests. The rich forest floor supports a diversity of spring wild flowers, including common and nodding trilliums, jack-in-the-pulpit, and squirrel corn. Animal diversity is also high, including forest songbirds, eastern box turtle and salamander.
Blowouts are U-shaped areas of open, migrating sand that occur on dunes otherwise stabilized by forest vegetation. Blowout formation is closely linked with Great Lake high-water levels.
Small ponds are common between the foredune and the backdune in many dune complexes. As a result of water level fluctuations, both the plant and animal life can change dramatically from year to year.