2015 National Resources Inventory

The National Resources Inventory (NRI) is a statistical survey of natural resource conditions and trends on non-Federal land in the United States. Non-Federal lands include privately owned lands, tribal and trust lands, and lands controlled by state and local governments.

National Non-Federal Forest Land


Non-Federal Forest Land
In thousands of acres, with margins of error
Forest Land Type 1982 1987 1992 1997 2002 2007 2012 2015
Grazed Forest Land 70,648.7
± 1,996.8
± 2,104.6
± 2,025.8
± 2,045.6
± 1,577.3
± 1,433.2
± 1,514.0
± 1,569.4
Not Grazed Forest Land 340,233.9
± 1,449.0
± 1,518.1
± 1,509.1
± 1,512.0
± 2,350.8
± 2,390.2
± 2,436.0
± 2,526.9
Total Forest Land 410,882.6
± 2,393.4
± 2,564.6
± 2,581.8
± 2,604.0
± 2,498.5
± 2,466.3
± 2,550.6
± 2,643.4
Forest Land bar chart, see Forest Land table for data values

About the Data

Estimates presented here are based upon the latest information from the National Resources Inventory (NRI). The NRI is a longitudinal sample survey based upon scientific statistical principles and procedures. It is conducted by the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS), in cooperation with Iowa State University’s Center for Survey Statistics and Methodology.

These results are based upon the 2015 NRI, which provides nationally consistent data for the 30-year period 1982–2015. Current estimates cover the contiguous 48 States, Hawaii, and the Caribbean Area.

Release of NRI results is guided by NRCS policy and is in accordance with OMB and USDA Quality of Information Guidelines developed in 2001. NRCS is releasing NRI estimates only when they meet statistical standards and are scientifically credible in accordance with these policies; also, measures of statistical uncertainty are provided for all 2015 NRI estimates released to the public.

The findings on land use come from the NRI data category "Land Cover/Use," which comprises mutually exclusive categories such as cropland, rangeland, forest land, other rural land, developed land, and water areas. The NRI uses this classification to account for every acre of non-Federal land within the Nation. Every parcel of land is described by one and only one of these categories.

The NRI approach to conducting inventories facilitates examining trends in rural and developed land uses over time because—

  • the same sample sites have been studied since 1982;
  • the same data have been collected since 1982 [definitions and protocols have remained the same];
  • the inventory accounts for 100 percent of the surface area;
  • quality assurance and statistical procedures are designed/developed to ensure that trend data are scientifically legitimate and unambiguous; and
  • it is easy to track lands as they go from one land-use category to another.

Irrespective of the scale of analysis, margins of error must be considered. Margins of error (at the 95 percent confidence level) are presented for all NRI estimates. Note that estimates of change between two points in time will be less precise (relatively) than estimates for a single inventory year because the changes will be occurring on a smaller fraction of the landscape.


  • 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 land cover. The NRI uses the term land cover/use to identify categories that account for all the surface area of the United States.
    • Forest land. A land cover/use category that is at least 10 percent stocked by single-stemmed woody species of any size that will be at least 4 meters (13 feet) tall at maturity. Also included is land bearing evidence of natural regeneration of tree cover (cut over forest or abandoned farmland) and not currently developed for nonforest use. Ten percent stocked, when viewed from a vertical direction, equates to an areal canopy cover of leaves and branches of 25 percent or greater. The minimum area for classification as forest land is 1 acre, and the area must be at least 100 feet wide.
      • Forest land, grazed. A category under forest land cover/use that includes forest land that is being grazed by livestock and managed using range or pasture management principles and practices adapted to the forest ecosystem.
      • Forest land, not grazed. A land cover/use category that includes areas meeting the definition of forest land (at least 10 percent stocked by single-stemmed woody species of any size that will be at least 4 meters [13 feet] tall at maturity) that is not visibly grazed or otherwise disturbed by domestic livestock.
  • Margins of Error. Margins of error are reported for each NRI estimate. The margin of error is used to construct the 95 percent confidence interval for the estimate. The lower bound of the interval is obtained by subtracting the margin of error from the estimate; the upper bound is obtained by adding the margin of error to the estimate. Confidence intervals can be created for various levels of significance which is a measure of how certain we are that the interval contains the true value we are estimating. A 95 percent confidence interval means that in repeated samples from the same population, 95 percent of the time the true underlying population parameter will be contained within the lower and upper bounds of the interval.

For more definitions see the full 2015 NRI Glossary.

More Information

For more information about the NRI, visit http://www.nrcs.usda.gov/technical/NRI/

Send comments and questions to the NRI Help Desk

Citation for this website:
U.S. Department of Agriculture. 2015.
2015 National Resources Inventory.
Natural Resources Conservation Service, Washington, DC. 31 October 2018 *

*[use date the website was accessed]