Spruce forest, Oregon, July 2003.
Credit: National Oceanic and Atmospheric
AdministrationBefore European settlement, forests covered nearly one billion
acres of what is now the United States. Since the mid-1600's, about
300 million acres of forest have been cleared, primarily for agriculture
during the 19th century. Today about one-third of the nation is
forested. While total forest area has been relatively stable for
the last 100 years (currently about 747 million acres), there have
been significant regional shifts in the area and composition of
the nation's forests. Reversion of marginal farmland in the east,
large scale planting in the South, and fire suppression have contributed
to increases in forest area. Urbanization, conversion to agriculture,
reservoir construction, and natural disasters have been major factors
contributing to loss of forests.
Eastern forests cover about 384 million acres and are predominantly broadleaf (74%),
with the exception of extensive coniferous
forests and plantations in the southern coastal region. These
are largely in private ownership (83%). By contrast, about 363
million acres of western forests are predominantly coniferous (78%)
and in public ownership (57%). Nearly ten million private individuals
own about 422 million acres of forest and other wooded land. Most
public forest land is held by four Federal agencies (Forest
Service, Bureau of Land Management, National
Park Service, Fish and Wildlife
Service) as well as numerous state, county, and municipal
Major uses of forests include timber production, recreation, hunting,
fishing, watershed and fisheries protection, wildlife habitat and
biodiversity protection, and gathering nontimber products such
as berries, mushrooms, and medicinal plants.
The forest cover types found on the National Atlas Forest Cover
map and map
layer were derived from Advanced
Very High Resolution Radiometer (AVHRR) composite images recorded
during the 1991 growing season. Each composite covered the United
States at a resolution of one kilometer. Field data collected by
the Forest Service were used to aid the classification of AVHRR
composites into forest cover types. Details on development of the
forest cover types dataset are in an article written by Zhu and
Eyre, F.H., 1980, Forest Cover Types of the United States and
Canada: Society of American Foresters,
Smith, W.B., Vissage, J.S., Darr, D.R., and Sheffield, R.M., 2000, Forest
Resources of the United States, 1997: St. Paul, MN, U.S.
Department of Agriculture Forest Service.
Zhu, Z. and Evans, D.L., 1994, U.S. Forest Types and Predicted
Percent Forest Cover from AVHRR Data: Photogrammetric
Engineering and Remote Sensing, v. 60, No. 5, p. 525-531.