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Percent Change in Rangeland Area, 1982-1997
Description
This shaded polygon map shows the percent change
in the amount of Rangeland area from 1982 to
1997 within each 8 digit hydrologic unit, using
1982 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%. Areas with less
than 5% rangeland in either 1982 or 1992 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.
Data are not collected on Federal land. Data are
not shown for areas where rangeland is less than
5% of the total area. 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:
8 Digit Hydrologic Unit Areas with Federal Land
Other Layers Displayed:
State
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]
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.
[NRI-97]
Product Information
Product ID:
5019
Production Date:
1/12/01
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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