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Total Pastureland in 1997 and Percent Change in Area, 1992 - 1997
Description
This shaded polygon map shows the percent change
in the amount of rangeland area from 1992 to
1997 within each 8 digit hydrologic unit, using
1992 as a base year. The percentages are
presented in five categories based on the
following divisions: an increase of more than
25%, an increase of 5% to 25%, little change
(less than 5% change), a decrease of 5% to 25%,
and a decrease of over 25%. The total amount of
rangeland is indicated by brown dots with each
dot representing 25,000 acres. There was a
total of 406 million acres of rangeland in 1997,
5.2 million acres increased from 1992, 401
million acres did not change, 6.6 million acres
decreased from 1992. Areas where rangeland
occupy less than 5% of the total area in either
year are hatched. Areas with 95% or more Federal
area are shaded gray.
Cautions for this Product:
Areas with small amounts of rangeland may have
very high rates of change. This map may not be
used to determine site-specific information.
Within an 8-digit hydrologic unit, dot counts
represent acreage totals correctly plus or minus
one dot to account for remainders. Data are
not collected on Federal land. Data are not
available for Alaska or the Pacific Basin. Data
for Puerto Rico and the U.S. Virgin Islands are
aggregated by 6-digit hydrologic unit.
Sources
Source:
National Resources Inventory, 1997
Distributor:
USDA-NRCS-RIAD
Reliability:
NRI sample data are generally reliable at the
95% confidence interval for state and certain
broad substate area analyses. Generally,
analyses that aggregate data points by smaller
geographic areas and/or more specific criteria
result in fewer data points for each aggregation
and therefore less reliable estimates. NRI maps
reflect national patterns rather than site-
specific information.
Layers
Aggregate Layer:
Cross of State with 8 Digit Hydrologic Units and
Federal Land
Other Layers Displayed:
States, Rivers
Definitions
Federal land:
A land ownership class designating land that is
owned by the Federal Government. It does not
include, for example, trust lands administered
by the Bureau of Indian Affairs nor Tennessee
Valley Authority (TVA) land. No data are
collected for any year that land is in this
ownership. [NRI-97]
Land cover/use:
A term that includes categories of land cover
and categories of land use. Land cover is the
vegetation or other kind of material that covers
the land surface. Land use is the purpose of
human activity on the land; it is usually but
not always related to the land cover. The NRI
uses the term (land cover/use) to identify the
categories that account for all the surface area
in the United States [BS-1982; NRI-97]
Rangeland:
A Land cover/use category on which the climax or
potential plant cover is composed principally of
native grasses, grasslike plants, forbs or
shrubs suitable for grazing and browsing, and
introduced forage species that are managed like
rangeland. This would include areas where
introduced hardy and persistent grasses, such as
crested wheatgrass, are planted and such
practices as deferred grazing, burning,
chaining, and rotational grazing are used, with
little or no chemicals or fertilizer being
applied. Grasslands, savannas,
many wetlands, some deserts, and tundra are
considered to be rangeland. Certain communities
of low forbs and shrubs, such as mesquite,
chaparral, mountain shrub, and pinyon-juniper,
are also included as rangeland.
Product Information
Product ID:
4977
Production Date:
12/13/00
Product Type:
Map
For additional information
contact the Resources Inventory and Assessment Division.
Please include the Product ID you are inquiring about.
nri@wdc.usda.gov
or 1400 Independence Avenue SW - P.O. Box 2890 -
Washington D.C. 20013. If you use our analysis products,
please be aware of our disclaimer.
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