The Atlantic coastal pine barrens is a now rare temperate coniferous forest ecoregion of the Northeast United States distinguished by unique species and topographical features (coastal plain ponds, frost pocket), generally nutrient-poor, often acidic soils and a pine tree distribution once controlled by frequent fires.

The white cedars often grow from pools of standing water and, in contrast to the surrounding pine forests, considerably darken the understory.

In openings and edges grow highbush blueberry, dangleberry, swamp azalea (Rhododendron viscosum), fetterbush (Eubotrys racemosa), and leatherleaf (Chamaedaphne calyculata).

[6][page needed] Poison ivy (Toxicodendron radicans) and Japanese honeysuckle (Lonicera japonica) are often abundant and grow in thickets.

Shrubs include arrowwood (Viburnum dentatum), spicebush (Lindera benzoin), highbush blueberry (Vaccinium corymbosum), sweet pepperbush (Clethra alnifolia), and swamp azalea.

[6] The region also contains areas of maritime grassland on Martha's Vineyard, Nantucket, and out at the tip of Long Island that are unique in the United States (see Conscience Point National Wildlife Refuge for an example).

Wildlife adapted to this environment includes the Pine Barrens tree frog, Plymouth red-bellied turtle and the extinct heath hen.

The pine barrens ecosystems have been severely damaged by urban developments as the east coast has become built up with housing, including vacation and retirement properties.