Major Dune Systems

Dunes

Major Dune System, Sandwich (.jpg - 52k)

Major dune systems are harsh environments, formed by wind, and characterized by having both primary and secondary dunes and dune bogs. Mounds of sand are stabilized by vegetation, and slowly built into a dune by the wind.

Significant dune migration occurs by the wind picking up sand grains from the dune's windward base and bouncing the grains over the crest to the leeward side, in a process called saltation. The dune's windward base may be eroded down to the point where it is intersected by the water table. Here, in wet months, pools may form, which are quickly colonized by cranberries (Vaccinium macrocarpon), sedges and wildflowers. This region is the dune bog, and it provides an unusual habitat for many types of wildlife.

Dunes are stabilized by vegetation, but poor land-clearing and agricultural practices over the last three centuries destroyed much dune vegetation, thus letting wind reach the sands. Eventually, these cleared dunes were recolonized by grasses, and succession has led to the pitch pine forests of today.

There are five major dune systems on Cape Cod: the Provincelands in Provincetown and Truro, Sandy Neck in Barnstable, Monomoy Island in Chatham, Chapin Memorial Beach in Dennis, and Chapoquoit Beach in Falmouth.

Plants and animals found in dune habitats may be hurt or killed by foot traffic and off-road vehicles.