Fragmentation statistics for FIA: designing an approach

—The USDA Forest Inventory and Analysis (FIA) program collects data on the amount of forest, as well as on characteristics such as forest type, tree volume, species composition, and size and age classes. However, little data are obtained nationwide on forest fragmentation—how that forest is distributed and in what land use/land cover context—factors that can substantially affect forest composition and health, wildlife, water quality, and forest management. In this paper we examine which fragmentation and context metrics should be linked with FIA plot data and monitored over time, and we identify possible sources of land use/land cover data from which to calculate this information. Emphasis is placed on those metrics that have been observed to be indicators of change in forested ecosystems. Using a complete set of photointerpreted land use/cover data in Massachusetts as the “truth,” we examine one possible source, the 1992 National Land Cover Dataset (NLCD) for its “fragmentation accuracy.” With accurate, relevant, and consistent fragmentation and context information, FIA will be able to better understand, interpret, and report on the state of the forest. FIA data collected from extensive sample plots across the United States are reported in a variety of statistical and analytical publications. Such reports include valuable information on the amount of forest in a particular State, county, or watershed, as well as total tree volume, forest type, species composition, size and age classes, and so on. However, typically little data are collected and analyzed on forest fragmentation—how that forest is distributed across the landscape. For example, we do not know whether those acres of forest occur as part of a large matrix or are distributed as many smaller patches. Nor do we know how isolated or connected those patches are, what land use/land cover context the forest is in, or how much of the forest is in interior vs. edge conditions. Figure 1 illustrates two areas of roughly equal 1 Research Forester, Forester, Group Leader, and Research Forester, respectively, Northeastern Research Station, U.S. Department of Agriculture, Forest Service, Newtown Square, PA 19073. Phone: (518) 285-5607; e-mail: rriemann@fs.fed.us Figure 1.—Two