The Society of American Foresters has defined the following 24 major forest cover types in the United States:

Forest Cover Types: Continental United States and Alaska

White-red-jack pine
Indicator species: eastern white pine, red pine, jack pine
Common associates: hemlock, aspen, birch, maple

Spruce-fir
Indicator species: spruce, fir
Common associates: white cedar, tamarack, maple, birch, hemlock

Longleaf-slash pine
Indicator species: longleaf pine, slash pine
Common associates: other pines, oak, gum

Loblolly-shortleaf pine
Indicator species: loblolly pine, shortleaf pine, southern yellow pines, except longleaf or slash pine
Common associates: oak, hickory, gum

Oak-pine
Indicator species: oak, pine, eastern red cedar
Common associates: gum, hickory, yellow poplar

Oak-hickory
Indicator species: oak, hickory
Common associates: yellow poplar, elm, maple, black walnut

Oak-gum-cypress
Indicator species: tupelo, blackgum, sweetgum, oak, southern cypress
Common associates: cottonwood, willow, ash, elm, hackberry, maple

Elm-ash-cottonwood
Indicator species: elm, ash, cottonwood
Common associates: willow, sycamore, beech, maple

Maple-beech-birch
Indicator species: maple, beech, yellow birch
Common associates: hemlock, elm, basswood, white pine

Aspen-birch
Indicator species: aspen, balsam poplar, paper birch, gray birch
Common associates: maple, balsam fir

Douglas fir
Indicator species: Douglas fir
Common associates: western hemlock, western red cedar, other firs, redwood, ponderosa pine, larch

Hemlock-Sitka spruce
Indicator species: Western hemlock, Sitka spruce
Common associates: Douglas fir, silver fir, western red cedar

Redwood
Indicator species: redwood
Common associates: Douglas fir, grand fir, tanoak

Ponderosa pine
Indicator species: ponderosa pine
Common associates: Jeffrey pine, sugar pine, limber pine, Arizona pine, Apache pine, Chihuahua pine, Douglas fir, incense cedar, white fir

Western white pine
Indicator species: western white pine
Common associates: western red cedar, larch, white fir, Douglas fir, lodgepole pine, Engelmann spruce

Lodgepole pine
Indicator species: lodgepole pine
Common associates: alpine fir, western white pine, Engelmann spruce, aspen, larch

Larch
Indicator species: western larch
Common associates: Douglas fir, grand fir, western red cedar, and western white pine.

Fir-spruce
Indicator species: fir, Engelmann spruce, Colorado blue spruce
Common associates: mountain hemlock, lodgepole pine

Western hardwoods
Indicator species: aspen, red alder, other western hardwoods

Chaparral
Indicator species: dwarfed trees and shrubs including pine, oak, cypress, madrone, fir

Pinyon-juniper
Indicator species: pinyon pine, juniper

Spruce-birch
Indicator species: White spruce, paper birch, quaking aspen, balsam poplar

Forest Cover Types: Hawaii

Native Forest
Mixed forest

To view an interactive map of the various forest cover types, please visit the National Atlas of the United States’s Forest Resources Map.

Different systems have been developed by organizations such as the World Wildlife Federation and the US Environmental Protection Agency/Commission for Environmental Cooperation to define different types of forest ecosystems of communities.