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Mapping the Fire Danger Zone

Visitors to the forests and waterways of northern Wisconsin can see that the landscape is changing. Clusters of homes and resorts are springing up along the lakeshores and in the woods, dividing the natural landscape into smaller and smaller fragments. Both in Wisconsin and across the nation, these wildland/urban interfaces-where residential areas meet undeveloped vegetation-are increasingly the sites of environmental conflict, including the destruction of homes by wildfires.

To help federal agencies and local authorities manage fire risk, a team of College of Agricultural and Life Sciences and U.S. Department of Agriculture Forest Service researchers has analyzed and combined existing census and vegetation data in an innovative way. The result of this partnership is a new understanding of wildland/urban interfaces across the country, and a map that reflects congressional policymakers” definitions of at-risk communities. The CALS researchers have also created a website with maps and data about the national landscape, which is already being used by fire managers and scientists.

Fire management, though always an important issue, was thrust into the spotlight following the catastrophic western wildfires in 2000. “At the national level, there was a question of how best to allocate the additional funding Congress set aside to manage fire risk,” explains Volker Radeloff, a CALS assistant professor of forest ecology and management. “To do this effectively, we want to know where people are building houses in the woods, and what ecosystems are being most affected.”

Radeloff is an expert in geographic information systems, and knew that he could use land cover data from the United States Geological Survey to classify areas according to vegetation type. However, the project needed the perspective of Roger Hammer, a CALS rural sociologist, to incorporate census data and handle demographic variables. “Volker and I began working together after other colleagues noticed that even though we are in different fields, we work with similar techniques,” Hammer explains. “Our analysis-which integrated demographic and satellite information-was fairly unique.”
“The partnership was crucial,” Radeloff adds. “This project was only possible because we collaborated from separate parts of the College to use existing data in a completely new way.” They began their research in 2002 with support and assistance from the USDA Forest Service.

Using a collaborative approach, the team found that 9 percent of all land area in the lower 48 states can be classified as wildland/urban interface, which includes one-third of all homes. The data shows that the eastern United States contains more interface areas-reaching a maximum at 72 percent of the land area in Connecticut-but that California has the highest number of affected homes.

“We also noted that while the devastating 2003 California wildfires affected 533 square kilometers of wildland/urban interface areas, and burned more than 3,600 structures, that represents only about five percent of southern California”s total interface area,” says Radeloff. “This highlights the need for ecological principles in land-use planning, as well as sprawl-limiting policies.” Hammer adds that analysis of one 2003 California wildfire shows that the entire periphery of the fire was largely wildland/urban interface.

In Wisconsin, Radeloff says that Vilas and Oneida counties show the most wildland/urban interface expansion. There is also strong growth in areas of the state that have the highest fire risk, including the central sands region. On land protected by the Wisconsin Department of Natural Resources, about 1,500 fires burn more than 5,000 acres annually. While many fires burn less than an acre, Wisconsin has had fires burn hundreds and thousands of acres of land across the state. This year, there is some cause for heightened concern, because the spring-Wisconsin”s peak fire season-began with a drought.

To assist researchers and fire managers, Radeloff and Hammer have made wildland/urban interface maps available online at There is also an interactive mapping tool where users may create, modify, and print their own custom WUI maps on the web at
The site is already being used to identify areas that need fire planning and outreach. “These maps were designed to be usable, and to help fire managers and policy makers implement fire policy,” adds Susan Stewart, a project collaborator and research social scientist with the Forest Service”s North Central Research Station.

Hammer and Radeloff intend to apply this research to Nicolet National Forest in northern Wisconsin. They will work with forest managers to study how low-density housing affects wildfires in the Langlade and Oconto counties.

The collaborative wildland/urban interface project was funded by the National Fire Plan and supported by the state of Wisconsin.