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Percent Change in Rangeland Area, 1982-1992

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Description

This shaded polygon map shows the percent change in the amount of Rangeland area from 1982 to 1992 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. This map replaces map #2309.

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: 5018
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.