Note that the data published in the 2002 State of the Nation’s Ecosystems Report as well as the 2003 and 2005 Web-Only Updates have been superseded by the 2008 Report and thus should be used with caution. For the most recent data, purchase the 2008 Report from Island Press.

Discussion This analysis does not distinguish between fragmentation caused by human activity (development, agriculture, etc.) and natural patchworks of forest and nonforest cover. Many western forests in particular are characterized by natural intermingling of forest and grasslands or shrublands.

The satellite remote sensing data presented here can generally identify forest features that are at least 10,000 feet square, or about 100 feet on a side. Thus, features that are narrower than about 100 feet—for example, some roads, powerlines, residential development within otherwise-wooded areas, or other small nonforest land uses—are missing. (Somewhat larger features may also be missed if they are split between multiple pixels.) Future analyses could include these smaller features by using satellite data that can discern smaller nonforest areas, or using ancillary information, such as mapped databases showing the location of these smaller features.

This analysis treats all nonforest land uses similarly, whether they are clumped together, spread evenly across a landscape, or strung together in a line (e.g., as a road or powerline). Different types of breaks in forest cover may affect forests in different ways—concentrations of nonforest cover may have major impacts on local habitat suitability, while linear features such as roads can serve as barriers to species movement. Future analyses might weight some nonforest areas or patterns more than others.

The “neighborhoods” used in this analysis are intended to provide a perspective on forest pattern, not to represent the habitat needs of particular species.