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Transactions of the Symposium on Photo Interpretation

once managed only for timber production are now managed for multiple pur
poses. As a result of these gradual changes the need for soil surveys on forested,
mountain lands is becoming an important item in plan development and
decision making for present and future uses.
The forested land of the U.S. (excluding interior Alaska and Hawaii)
approximates 664,000,000 acres (269,000,000 hectares) of which 358,000,000
acres are commercial private holdings, 130,000,000 acres are commercial
public holdings and 176,000,000 acres are noncommercial forested lands. The
U.S. Forest Service is responsible for the management of 186,000,000 acres
of this land but not all of this grows commercial forests. Fully 90 percent of
this National Forest land is steep and mountainous. Six to seven million acres
occur above timberline. Only about 10 percent of the commercial stands are
original or virgin stands - all the remainder has been given some form of treat
ment once or several times.
Decreasing supplies and increasing demands for forest products make
necessary increasing levels of management. Soils in nurseries and seed orchards
are, of course, the most carefully selected and intensively managed. The next
most intensively managed forested lands are those areas in portions of the
country where the precipitation is great, the growing seasons long and com-
petive markets exist. These situations justify considerably larger quantities of
management inputs per unit of area and, as a result, careful selection of soils.
Information about soils is useful at several planning levels. At the multiple
use or general area plan level in the U.S. Forest Service the soils are placed in
broad groups called Soil Management Areas. Each soil management area has
broadly similar physical characteristics, problems and potentialities that form
the basis of decisions for program planning. These soil management areas are
generalizations of data from the soil survey report and map. Within each of the
soil management areas some soils may be strongly contrasting with respect to
their use and management. These contrasting soils are taken into account at
the next planning level in the project plans. There may be a project plan for
timber harvest or tree planting, range management, watershed management,
recreation developments and other resource uses. At the project level it is
important to know the potentialities and limitations of individual kinds of soils.
The soil survey report and map is the source of this information. In addition,
special problem areas require plans that provide for the treatment of land after
fires, floods or accelerated erosion, etc. In these cases large-scale maps that pin
point small soil areas are prepared and special recommendations are made
for the treatment of the individual soils.
The field operations of soil classification and mapping of forested, steep
mountain lands are much more difficult than the same operation on most
cultivated lands.
Accessibility is one of the first problems. We have many vast areas of forested