Atlantic white cedar swamps occur as basin, seepage or streamside wetlands. They often develop on poorly drained depressions or kettle holes along the coast or along major river corridors. The cedar trees form dense stands that obstruct the sunlight from reaching the forest floor. Shrubs in this habitat include sweet pepperbush, winterberry and highbush blueberry. Oak fern, long beech fern, goldthread and sphagnum moss form the ground layer. Historically, the lumber in such swamps was harvested, the land drained and cleared for cranberry bogs.