A wildfire, also known as a forest fire or bushfire (in Australasia), is an uncontrolled fire in wildland often caused by lightning; other common causes are human carelessness and arson.

Drought and the prevention of small forest fires are major contributors to extreme forest fires.

Contents

1 Background 2 Behavior 3 Prevention 4 Fire suppression 5 Famous wildfires 5.1 In North America 6 See also 7 External links 8 Further reading 9 Other uses of wildfire

Background

Wildfires are common in many places around the world, including much of the vegetated areas of Australia, forest areas of the United States and Canada, where the climates are sufficiently moist to allow the growth of trees, but feature extended dry, hot periods when fallen branches, leaves, and other material can dry out and becomes highly flammable. Wildfires are also common in grasslands and scrublands. Wildfires tend to be most common and severe during years of drought and occur on days of strong winds. With extensive urbanization of wildlands, these fires often involve destruction of suburban homes located in the wildland urban intermix.

Today it is accepted that wildfires are a natural part of the ecosystem of wildlands, where, at the least, plants have evolved to survive fires by a variety of strategies (from possessing reserve shoots that sprout after a fire, to fire-resistant seeds), or even encourage fire (for example eucalypts contain flammable oils in the leaves) as a way to eliminate competition from less fire-tolerant species. In 2004, researchers discovered that exposure to smoke from burning plants actually promotes germination in other types of plants by inducing the production of the chemical butenolide. Most native animals, too, are adept at surviving wildfires.

On occasions, wildfires have caused large-scale damage to private property, particularly when they have reached urban-fringe communities, destroying many homes and causing deaths.

Slash, small, rotten, mis-shapen, or otherwise undesirable wood discarded during logging, has historically provided the fuel for devastating fires such as the fires in Michigan in the 19th century.

The aftermath of a wildfire can be as disastrous if not more so than the actual fire itself. A particularly destructive fire burns away all the plants and trees which prevented erosion. If heavy rains occur after such a fire, landslides, ash flow s, and flash floods are to be expected. Not only does this result in severe property damage for those living in the immediate fire area, but it also affects the quality of the local water supply.

Behavior

The Nevada Bureau of Land Management identifies several different wildfire behaviors. For example, extreme fire behavior includes wide rates of spread, prolific crowning and/or spotting, the presence of fire whirl s, or a strong convection column . Extreme wildfires behave erratically and unpredictably.

In southern California, under the influence of Santa Ana winds, wildfires can move at tremendous speeds, up to 40 miles (60 km) in a single day, conusming up to 1,000 acres (4 km²) per hour. Dense clouds of burning embers push relentlessy ahead of the flames crossing firebreaks without pause.

The powerful updraft caused by a large wildfire will draw in air from surrounding areas. These self-generated winds can lead to a phenomenon known as a firestorm.

Prevention

For many decades the policy of the United States Forest Service was to suppress all fires, and this policy was epitomized by the mascot Smokey Bear and was also the basis of parts of the movie Bambi. The policy began to be questioned in the 1960s, when it was realized that no new sequoias had been grown in the redwood forests of California, because fire is an essential part of their life cycle. This produced the policy of controlled burns to reduce underbrush. This clears much of the undergrowth through forest and woodland areas, making travel and hunting much easier while reducing the risk of dangerous high-intensity fires caused by many years of fuel buildup.

However, the previous policy of absolute fire suppression in the United States had resulted in the buildup of fuel resulting in large and severe fires such as the fire in Yellowstone National Park in 1988. Urbanization can also result in fuel buildup and devastating fires, such as those in Los Alamos, New Mexico, East Bay Hills, within the California cities of Oakland and Berkeley, between October 19 and 22, 1991, all over Colorado in 2002, and throughout Southern California in October, 2003.

On average, wildfires burn 4.3 million acres (17,000 km²) in the United States annually. In recent years the federal government has spent $1 billion a year on fire suppression. 2002 was a record year for fires with major fires in Arizona, California, Colorado, and Oregon.

The risk of major wildfires can be reduced by reducing the amount of fuel present. In wildland, this can be accomplished by either conducting "controlled burns" - deliberately setting areas ablaze under less dangerous weather conditions in spring or autumn - or physical fuel removal by removing some trees as is conducted in many American forests. Both approaches are controversial with some environmentalists, who regard them as tampering with the forest ecosystem.

People living in fire-prone areas typically take a variety of precautions, including building their homes out of flame-resistant materials, reducing the amount of fuel near the home or property (including firebreaks - their own miniature control lines, in effect), and investing in their own firefighting equipment.

Rural farming communities are rarely threatened directly by wildfire. These types of communities are usually located in large areas of cleared, usually graze d, land, and in the drought conditions present in wildfire years there is often very little grass left on such grazed areas. Hence the risk is minimized. However, urban fringes have spread into forested areas, for example in Sydney and Melbourne, and communities have literally built themselves in the middle of highly flammable forests. These communities are at high risk of destruction in bushfires.

Fire suppression

Most fire-prone areas have large firefighter services to help control bushfires. As well as the water-spraying trucks most commonly used in urban firefighting, bushfire services use a variety of alternative techniques. They often possess aircraft, particularly helicopters, that can douse areas that are inaccessible to ground crews and deliver greater quantities of water and/or flame retardant chemicals. However, large fires are of such a size that no conceivable firefighting service could attempt to douse the whole fire directly, and so alternative techniques are used.

In alternative approaches, firefighters attempt to control the fire by controlling the area that it can spread to, by creating "control lines", which are areas that contain no combustible material. These control lines can be produced by physically removing fuel (for instance, with a bulldozer), or by "backburning", in which small, low-intensity fires are started to burn the flammable material in a (hopefully) controlled way. These may then be extinguished by firefighters, or, ideally, directed in such a way that they meet the main fire front, at which point both fires run out of flammable material and are thus extinguished.

Unfortunately, such methods can fail in the face of wind shifts causing fires to miss control lines or to jump straight over them (for instance, because a burning tree falls across a line, burning embers are carried by the wind over the line, or burning tumbleweeds cross the line).

The actual goals of firefighters vary. Protection of life (those of both the firefighters and "civilians") is given top priority, then private property according to economic and social value and also to its "savability" (for example, more effort will be expended on saving a house with a tile roof than one with a wooden-shake roof). In very severe, large fires, this is sometimes the only possible action. Protecting houses is regarded as more important than, say, farming machinery sheds, although firefighters, if possible, try to keep fires off farmland to protect stock and fences (steel fences are destroyed by the passage of fire, as the wire is irreversibly stretched and weakened by it). Preventing the burning of publicly-owned forested areas is generally of least priority, and, indeed, it is quite common (in Australia, at least) for firefighters to simply observe a fire burn towards control lines through forest rather than attempt to put it out more quickly - it is, after all, a natural process.

Famous wildfires

In North America

• Miramichi Fire in New Brunswick, which burned three million acres (12150 km²) and killed 160 people. 1825
• Yachina Fire in Oregon, which burned 450,000 acres (1,800 km²) 1846
• Nestucca Fire in Oregon, which burned 320,000 acres (1,300 km²) 1853
• The Silverton Fire , the worst recorded fire in Oregon, which burned an estimated one million acres (4,000 km²) 1865
• The Coos Fire in Oregon, which burned 300,000 acres (1,200 km²) 1868
• The Peshtigo Fire in Wisconsin which burned 1,200,000 acres (4900 km²) in one day October 8, 1871 (overshadowed by the Great Chicago Fire, which occurred on the same day)
• Bighorn Fire in Wyoming, which burned 500,000 acres (2,000 km²) 1876
• Thumb Fire in Michigan, burned a million acres (4,000 km²) and killed 250+ people 1881
• The Hinckley Fire in Minnesota, burned 160,000 acres (650 km²), killed 418 people, and destroyed 12 towns 1894
• The Adirondack Fire in New York, which burned 450,000 acres (1,800 km²) 1903
• The Great Fire of 1910 , burned about three million acres (12,000 km²) in Idaho and Montana over two days (August 20 and 21), killed 86 people
• The Tillamook Burn, which swept through the same region of Oregon four times, and burned a total of 355,000 acres (1,400 km²) 1933, 1939, 1945, and 1951
• A series of fires in Maine over ten days, burned 175,000 acres (710 km²) and killed 16 people 1947
• The Laguna Fire burned 175,425 acres (710 km²), 382 homes and kills eight in San Diego County in September 1970. It was the largest fire in California history until the Cedar Fire.
• Yellowstone National Park Fire, 800,000 acres (3,200 km²), 1988
• Oakland Hills firestorm, killed 25 and destroyed 3469 homes and apartments within the California cities of Oakland and Berkeley, between October 19 and 22, 1991.
• Glenwood Springs, Colorado1994
• Florida, 2200 fires, during 1998 drought, over 300,000 acres (1,200 km²) burned including 150 homes, $390 million timber lost, 80,000 evacuees, $133 million in fire suppression costs.
• Mesa Verde National Park 2000
• Rodeo-Chediski fire, Arizona, 2002 467,066 acres (1,890 km²) of woodland burned, June 18 to July 7, 2002, and threatened, but did not burn the town of Show Low, Arizona.
• Durango, Colorado fires 2002, 915,000 acres (3,700 km²) burned 9 firefighter deaths, 235 homes destroyed
• The Florence/Sour Biscuit Complex Fire , burned 499,570 acres (2,000 km²) in southwestern Oregon between July 13 and September 5, 2002
• Major fire inferno in the Okanagan district, British Columbia covering around 500,000 acres (2,000 km²), displacing more than 5,000 inhabitants, in August and September 2003
• The Cedar Fire burned 280,278 acres (1,134 km²), 2,232 homes and killed 14 in San Diego County. The largest fire in California history, it was one 15 major fires in Ventura, Los Angeles, San Bernardino, and San Diego counties in California covering 721,791 acres (2,920 km²), killing 24, displacing 120,000 and destroying 3,640 homes in October 2003. Damage estimated at 2 billion USD (See NASA images: [1] [2])

See also

• Defensible space

External links

• Current Wildland Fire Information
• FEMA report on the East Bay Hills Fire
• Global Fire Monitoring Center (GFMC)
• Interesting Forest Fire Policy

Further reading

• Fire in America: A Cultural History of Wildland and Rural Fire, Stephen J. Pyne, Princeton University Press, 1982, hardcover, 654 pages, ISBN 0-691-08300-2
• Year of the Fires, The Story of the Great Fires of 1910, Stephen J. Pyne, Viking Penguin, 2001, 320 pages, ISBN 0670899909
• Ghosts of the Fireground: Echoes of the Great Peshtigo Fire and the Calling of a Wildland Firefighter, Peter M. Leschak, HarperSanFrancisco, 2002, hardback, 288 pages, ISBN 0062517775

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Other uses of wildfire

• The singer/songwriter Michael Murphey released a song titled "Wildfire".
• Wildfire is the name of the secret underground biological testing facility in the book and movie The Andromeda Strain.
• The B-52's released a song called "Bushfire" on their album Cosmic Thing (1989).
• Wildfire is the name of a fictional substance, somewhat like napalm, in George R. R. Martin's A Song of Ice and Fire stories.
• "Wildfire" is a song on Sonata Arctica's album Reckoning Night