Description. Forested Wetlands are most common in the eastern United States and in those sections of the West where moisture is relatively abundant, particularly along rivers and in the mountains. They occur only in the Palustrine and Estuarine Systems and normally possess an overstory of trees, an understory of young trees or shrubs, and a herbaceous layer. Forested Wetlands in the Estuarine System, which include the mangrove forests of Florida, Puerto Rico, and the Virgin Islands, are known by such names as swamps, hammocks, heads, and bottoms. These names often occur in combination with species names or plant associations such as cedar swamp or bottomland hardwoods.

Subclasses and Dominance Types.

• Broad-leaved Deciduous. -- Dominant trees typical of Broadleaved Deciduous Wetlands, which are represented throughout the United States, are most common in the South and East. Common dominants are species such as red maple, American elm (Ulmus americana), ashes (Fraxinus pennsylvanica and F. nigra), black gum (Nyssa sylvatica), tupelo gum (N. aquatica), swamp white oak (Quercus bicolor), overcup oak (Q. lyrata), and basket oak (Q. michauxii). Wetlands in this subclass generally occur on mineral soils or highly decomposed organic soils.

• Needle-leaved Deciduous. -- The southern representative of the Needle-leaved Deciduous Subclass is bald cypress (Taxodium distichum), which is noted for its ability to tolerate long periods of surface inundation. Tamarack is characteristic of the Boreal Forest Region, where it occurs as a dominant on organic soils. Relatively few other species are included in this Subclass.

• Broad-Leaved Evergreen. -- In the Southeast, Broadleaved Evergreen Wetlands reach their greatest development. Red bay (Persea borbonia), loblolly bay (Gordonia lasianthus), and sweet bay (Magnolia virginiana) are prevalent, especially on organic soils. This Subclass also includes red mangrove, black mangrove (Avicennia germinans), and white mangrove (Languncularia racemosa), which are adapted to varying levels of salinity.

• Needle-leaved Evergreen. -- Black spruce, growing on organic soils, represents a major dominant of the Needle-leaved Evergreen Subclass in the North. Though black spruce is common on nutrient-poor soils, Northern white cedar (Thuja occidentalis) dominates northern wetlands on more nutrient-rich sites. Along the Atlantic Coast, Atlantic white cedar (Chamaecyparis thyoides) is one of the most common dominants on organic soils. Pond pine is a common needle-leaved evergreen found in the Southeast in association with dense stands of broad-leaved evergreen and deciduous shrubs.

• Dead. -- Dead Forested Wetlands are dominated by dead woody vegetation taller than 6 m (20 feet). Like Dead Scrub-Shrub Wetlands, they are most common in, or around the edges of, man-made impoundments and beaver ponds. The same factors that produce Dead Scrub-Shrub Wetlands produce Dead Forested Wetlands.