The wildland-urban interface: Evaluating the definition effect

Abstract

The wildland- urban interface (WUI) is the area where human-built structures and infrastructure abut or mix with naturally occurring vegetation types. Wildfires are of particular concern in the WUI because these areas comprise extensive flammable vegetation, numerous structures, and ample ignition sources. A priority of federal wildland fire policy in the United States is to help protect communities threatened by wildfire, creating a demand for maps of the WUI. In this study, five models of the WUI are compared for four counties in the United States. The models are all based on the widely cited characteristics of the WUI published in the Federal Register, although they differ slightly in their focus (vegetation or housing) and implementation (the details of the WUI definition). For models that differ in focus, I describe how the purpose of the map led to different results. For conceptually similar models, I assess how different effects-the "dasymetric effect," the "settlement representation effect," and the "merging buffer effect"-influence the extent of the WUI in different counties. The differences between the WUI maps can be more or less pronounced depending on the spatial distribution of housing, vegetation, and public land. No single mapping approach is unequivocally superior, and each has tradeoffs that need to be fully understood for use in management. © 2010 by the Society of American Foresters.