Defining the U.S. land base in support of the Resources Planning Act Assessment
By analyzing non-Federal land use trends, USDA Forest Service researchers, including Mark Nelson of the Northern Research Station, Kurt Riitters of SRS, and others from across the agency, found that developed land use in the South nearly doubled over the past 30 years, from 25.3 million acres in 1982 to 45.6 million acres in 2012.
Their technical report supports the decadal Resources Planning Act (RPA) Assessment. The RPA uses a combination of land use and land cover data to evaluate trends in the nation’s land base and project future changes. Land use describes the social and economic intent for which land is used, while land cover describes the vegetation, exposed land surfaces, water, and artificial structures covering the land surface.
In the South, almost ten million acres of forest land were lost to development. However, non-Federally owned forest land had a net gain of 1.9 million acres, due to the amount of cropland that converted to forest.
Southern cropland dropped from 106.6 million acres to 79.0 million acres. Millions of acres of pasture and rangeland were either developed or converted to forests.
Federal land and other non-agricultural rural uses each gained about 1 million acres in the South, while the Conservation Reserve Program gained 6 million acres.
To define land use and land cover of the conterminous U.S., the RPA Assessment draws from the Forest Inventory and Analysis Program (FIA), the National Resources Inventory (NRI) and the National Land Cover Database (NLCD). Each answered different questions in the report.
- The Forest Service’s FIA data were used to determine trends in forest land use across all ownerships.
- The statistics cited above came from the NRI, produced by USDA’s Natural Resources Conservation Service. The NRI cover a longer time and more land use classes than FIA but does not inventory Federal lands.
- The U.S. Geological Survey’s NCLD included high-resolution land cover maps enabling comparisons of land use and land cover trends.
- U.S. Census Bureau data measure human population density, which the RPA team combines with land use and land cover to assess trends in urban tree cover.
The databases differ in their sensitivity to the underlying drivers of landscape changes. Using them separately and in combination brings unique, complementary information to the RPA Assessment. Contact Claire O’Dea at claire.odea@usda.gov or visit the RPA Assessment site for more information.
Read the General Technical Report.
For more information, email Kurt Riitters at kurt.h.riitters@usda.gov.