Wildland fires triggered by lightning are both natural and inevitable and play an important ecological role on the nation’s landscapes. These fires shape the composition of forests and grasslands, periodically reduce vegetation densities, and stimulate seedling regeneration and growth in some species. Over the past century, however, various land use and management practices—including fire suppression, grazing, and timber harvesting—have reduced the normal frequency of fires in many forest and rangeland ecosystems and contributed to abnormally dense, continuous accumulations of vegetation. Such accumulations not only can fuel uncharacteristically large or severe wildland fires but also—with more homes and communities built in or near areas at risk from wildland fire— threaten human lives, health, property, and infrastructure. Moreover, the introduction and spread of invasive nonnative species (such as cheatgrass), along with the expanded range of certain flammable native species (such as western juniper) have also altered natural fire regimes, contributing to wildland fires’ burning in some areas with uncharacteristic frequency or intensity. The Forest Service, Bureau of Indian Affairs, Bureau of Land Management, Fish and Wildlife Service, and National Park Service are responsible for wildland fire management. These five agencies manage about 700 million acres of land in the United States, including national forests, national grasslands, Indian reservations, national parks, and national wildlife refuges. The Forest Service and the Bureau of Land Management manage the majority of these lands. The Forest Service manages about 190 million acres; the Bureau of Land Management manages about 260 million acres; and the Bureau of Indian Affairs, Fish and Wildlife Service, and National Park Service each manage less than 100 million acres. Figure 1 shows the distribution of land among the five agencies. Each agency has from 7 to 12 regional or state offices that oversee field units. The federal wildland fire management program has three major components: preparedness, suppression, and fuel reduction. To prepare for a wildland fire season, the agencies acquire firefighting assets— including firefighters, fire engines, aircraft, and other equipment—and station them either at individual federal land management units (such as national forests or national parks) or at centralized dispatch locations. The primary purpose of these assets is to respond to fires before they become large—a response referred to as initial attack—thus forestalling threats to communities and natural and cultural resources. The agencies fund the assets used for initial attack primarily from their wildland fire preparedness accounts. When a fire starts, current federal policy directs the agencies to consider land management objectives—identified in land and fire management plans developed by each land management unit—and the structures and resources at risk when determining whether or how to suppress the fire. A wide spectrum of strategies is available to choose from, and the land manager at the affected local unit is responsible for determining which strategy to use. In the relatively rare instances when fires escape initial attack and grow large, the agencies respond using an interagency system that mobilizes additional firefighting assets from federal, state, and local agencies, as well as private contractors, regardless of which agency or agencies have jurisdiction over the burning lands. Federal agencies typically fund the costs of these activities from their wildland fire suppression accounts. In addition to preparing for and suppressing fires, the agencies attempt to reduce the potential for severe wildland fires, lessen the damage caused by fires, limit the spread of flammable invasive species, and restore and maintain healthy ecosystems by reducing potentially hazardous vegetation that can fuel fires. Approaches used for managing vegetation include setting fires under controlled conditions (prescribed burns), mechanical thinning, herbicides, certain grazing methods, or combinations of these and other approaches. The agencies fund these activities from their fuel reduction accounts. Congress, the Office of Management and Budget, federal agency officials, and others have expressed concern about mounting federal wildland fire expenditures. Federal appropriations to the Forest Service and the Interior agencies to prepare for and respond to wildland fires, including appropriations for reducing fuels, have more than doubled, from an average of $1.2 billion from fiscal years 1996 through 2000 to an average of $2.9 billion from fiscal years 2001 through 2007. Adjusting for inflation, the average annual appropriations to the agencies for these periods increased from $1.5 billion to $3.1 billion (in 2007 dollars). The Forest Service received about 70 percent, and Interior about 30 percent, of the appropriated funds; table 1 shows the agencies’ combined fire appropriations for fiscal years 1996 through 2007. Analysis of structures damaged during past fires and experimental research have identified a number of relatively simple steps that can reduce the risk of damage to structures from wildland fire. Minimizing or preventing damage requires understanding the different types of wildland fire and how they can ignite structures. Surface fires—which burn vegetation or other fuels, such as shrubs, fallen leaves, small branches, and roots, near the surface of the ground—can ignite a home or other building by burning nearby vegetation and eventually igniting flammable portions of the building, including exterior walls or siding; attached structures, such as a fence or deck; or other nearby flammable materials, such as firewood or patio furniture. Crown fires—which burn the tops, or crowns, of trees—place homes at risk because they create intense heat, which can ignite portions of structures even without direct contact from flames. Embers, or “firebrands”—which can be carried on the wind a mile or more from a fire—can ignite a structure by landing on the roof or by entering a vent or other opening. Figure 2 illustrates how each type of fire can take advantage of a structure’s vulnerabilities and those of its immediate surroundings. Wildland fires can ignite homes and structures in different ways. Surface fires (A) can ignite a home by burning nearby vegetation. Crown fires (B) create intense heat, which can ignite portions of structures, without direct contact from flames. Firebrands (C), or embers, can ignite a home by landing on the roof or entering a roof vent or other opening. As the Forest Service and the Interior agencies have improved their understanding of wildland fire’s role on the landscape, their approach to managing fire has evolved. Under the new approach, the agencies seek to make the landscape less susceptible to damage by wildland fire and to respond to fires in ways that protect communities and important resources while also considering the cost and long-term effects of that response. Historically, the Forest Service and the Interior agencies generally viewed fire as a damaging force that they attempted to suppress quickly—as exemplified by the “10 a.m. policy,” in which the goal was to contain every fire by 10:00 the morning after it was reported. For decades, the agencies were often successful in this approach. This emphasis on suppression led to a substantial decline in the average number of acres burned annually from the 1930s through the 1970s. A number of damaging fires in the 1990s, however, led the agencies to fundamentally reassess their understanding of wildland fire’s role on the landscape. Their view of fire’s ecological role began to expand, from seeing benefits in a few ecosystems, like certain grasslands and forest types, to realizing that in many locations—particularly the arid West—fire was inevitable. In addition, they recognized that by allowing brush, small trees, and other vegetation to accumulate, their past success in suppressing fires was in part responsible for making recent fires more severe. The agencies’ increased awareness of fire’s benefits, as well as of the unintended negative consequences of suppression, led them in 1995 to develop the Federal Wildland Fire Management Policy, a policy they reaffirmed and updated in 2001. Under the policy, the agencies abandoned their attempt to put out every wildland fire, seeking instead to (1) make communities and resources less susceptible to being damaged by wildland fire and (2) respond to fires so as to protect communities and important resources at risk but also to consider both the cost and long- term effects of that response. As a result, the agencies have increasingly emphasized firefighting strategies that focus on land management objectives, which may lead them to use less aggressive firefighting strategies that can not only reduce costs in some cases but also be safer for firefighters by reducing their exposure to unnecessary risks, according to agency fire officials. In recent years, the Forest Service and the Interior agencies have taken steps to help them better achieve the Federal Wildland Fire Management Policy’s vision. In an effort to make the landscape less susceptible to damage from wildland fire, for example, they have reduced hazardous fuels and fostered fire-resistant communities. They have also improved their ability to respond efficiently and effectively to wildland fires that occur, including taking steps to (1) implement the federal wildland fire management policy, (2) improve decisions regarding fire management strategies, and (3) improve how they acquire and use firefighting assets. In an effort to reduce damage to communities and resources from wildland fire, the agencies have continued to reduce fuels and foster fire- resistant communities, but the extent to which these efforts have reduced risk is unknown. Reducing hazardous fuels. Reducing hazardous fuels—to keep wildland fires from spreading into the wildland-urban interface and to help protect important resources by lessening a fire’s intensity—is one of the primary objectives of the National Fire Plan. The agencies reported reducing fuels on more than 29 million acres from 2001 through 2008. The agencies have also improved the data they use to help identify lands where fuels need to be reduced and have taken steps to improve their processes for allocating fuel reduction funds and setting priorities for fuels projects. The agencies have nearly completed their geospatial data and modeling system, LANDFIRE, as we recommended in 2003. LANDFIRE is intended to produce consistent and comprehensive maps and data describing vegetation, wildland fuels, and fire regimes across the United States.