PreventionSee also: Fire protection 1985 Smokey Bear poster with part of his admonition, "Only you can prevent forest fires".
Wildfire prevention refers to the preemptive methods of reducing the risk of fires as well as lessening its severity and spread. Effective prevention techniques allow supervising agencies to manage air quality, maintain ecological balances, protect resources, and to limit the effects of future uncontrolled fires. North American firefighting policies may permit naturally caused fires to burn to maintain their ecological role, so long as the risks of escape into high-value areas are mitigated. However, prevention policies must consider the role that humans play in wildfires, since, for example, 95% of forest fires in Europe are related to human involvement. Sources of human-caused fire may include arson, accidental ignition, or the uncontrolled use of fire in land-clearing and agriculture such as the slash-and-burn farming in Southeast Asia.
In the mid-19th century, explorers from the HMS Beagle observed Australian Aborigines using fire for ground clearing, hunting, and regeneration of plant food in a method later named fire-stick farming. Such careful use of fire has been employed for centuries in the lands protected by Kakadu National Park to encourage biodiversity. In 1937, U.S. President Franklin D. Roosevelt initiated a nationwide fire prevention campaign, highlighting the role of human carelessness in forest fires. Later posters of the program featuredUncle Sam, leaders of the Axis powers of World War II, characters from the Disney movie Bambi, and the official mascot of the U.S. Forest Service, Smokey Bear.A prescribed burn in a Pinus nigra stand inPortugal
Wildfires are caused by a combination of natural factors such as topography, fuels, and weather. Other than reducing human infractions, only fuels may be altered to affect future fire risk and behavior. Wildfire prevention programs around the world may employ techniques such as wildland fire use and prescribed or controlled burns. Wildland fire use refers to any fire of natural causes that is monitored but allowed to burn. Controlled burns are fires ignited by government agencies under less dangerous weather conditions.
Vegetation may be burned periodically to maintain high species diversity, and frequent burning of surface fuels limits fuel accumulation, thereby reducing the risk of crown fires. Using strategic cuts of trees, fuels may also be removed by handcrewsin order to clean and clear the forest, prevent fuel build-up, and create access into forested areas. Chain saws and large equipment can be used to thin out ladder fuels and shred trees and vegetation to a mulch. Multiple fuel treatments are often needed to influence future fire risks, and wildfire models may be used to predict and compare the benefits of different fuel treatments on future wildfire spread.
However, controlled burns are reportedly "the most effective treatment for reducing a fire’s rate of spread, fireline intensity, flame length, and heat per unit of area" according to Jan Van Wagtendonk, a biologist at the Yellowstone Field Station. Additionally, while fuel treatments are typically limited to smaller areas, effective fire management requires the administration of fuels across large landscapes in order to reduce future fire size and severity.
Building codes in fire-prone areas typically require that structures be built of flame-resistant materials and a defensible space be maintained by clearing flammable materials within a prescribed distance from the structure. Communities in the Philippines also maintain fire lines 5 to 10 meters (16 to 33 ft) wide between the forest and their village, and patrol these lines during summer months or seasons of dry weather. Fuel buildup can result in costly, devastating fires as new homes, ranches, and other development are built adjacent to wilderness areas. Continued growth in fire-prone areas and rebuilding structures destroyed by fires has been met with criticism.
However, the population growth along the wildland-urban interface discourages the use of current fuel management techniques. Smoke is an irritant and attempts to thin out the fuel load is met with opposition due to desirability of forested areas, in addition to other wilderness goals such as endangered species protection and habitat preservation. The ecological benefits of fire are often overridden by the economic and safety benefits of protecting structures and human life. For example, while fuel treatments decrease the risk of crown fires, these techniques destroy the habitats of various plant and animal species. Additionally, government policies that cover the wilderness usually differ from local and state policies that govern urban lands.A ponderosa pine stand in the Bitterroot National Forest in Montana in 1909, 1948, and 1989. The increase in vegetation density was attributed to fire prevention efforts since