Visualizing a Safer Planet
for photos, stories, and videos of natural hazards!
What is wildland fire?
Like floods in stream systems, wildland fire is a natural occurrence in many ecosystems. Actually, fire plays an important role in maintaining the health of some ecosystems, such as prairies and oak savannas. However, when fire threatens human life or property, it is considered a natural hazard. Besides the obvious threat of hot flames causing materials to burn, fire can also send vast amounts of ash into the atmosphere, which can inhibit plant growth, reduce visibility, and interfere with the breathing of people and other animals. It can also set the stage for slope failures and flooding by destroying vegetation, which leaves slopes vulnerable to heavy rains long after the fire has burned out. Habitat loss, surface water contamination, and agricultural loses can also be caused by fire. Wildland fires, which are large fires often covering many square miles (kilometers) that can burn for many days, are most frequently ignited by lightning and sometimes by human activities, such as cigarette smoking and campfires. Wildland fires can generate hurricane-force winds and can quickly climb up steep terrain, such as mountain slopes. In fact, the steeper the slope, the faster a fire is likely to burn. Depending on weather conditions and emergency response, wildland fires can burn for hours, days, weeks, and even months.
Where do wildland fires
occur?
In the Northern Hemisphere, wildland fires most commonly occur in
southern grasslands and southern needleleaf forests, where vegetation
is abundant, humidity is usually low, and temperatures are warm.
Although fires occur less frequently in colder and wetter climates,
they are still a threat wherever vegetation grows. In the United
States, most wildland fires occur in the western region that extends
from the Rocky Mountain Front Range to the Pacific Coast. In canyons
and valleys, wildland fire can be particularly dangerous because the
narrow canyons and valleys concentrate winds, which can increase a
fire's intensity while providing few escape routes. In Colorado and
California, the Chinook winds and
Santa Ana winds are often associated with these topography driven
wildland fires. In the year 2002, over 50,000 fires burned almost 5
million acres in 10 western states in the U.S. Over 1800 homes were
damaged or destroyed. Although this is the yearly average number of
fires, it is over twice the yearly average number of acres.
When do wildland fires
occur?
Fire is a potential hazard whenever vegetation becomes dry. This often
occurs as the result of drought
during the growing season. Since lightning is most common during the
growing season, dry weather prior to thunderstorms during Spring,
Summer, or Fall increases the risk of a wildland fire ignited from
lightning. Wildland fires are also more likely when trees become
diseased, which can be caused by insects, fungus, pollution, or any
combination of these factors. In the western United States, climate change is likely increasing
the populations of pine and spruce beatles that are infesting the
mountainous evergreen forests with a deadly fungus and causing high
rates of tree mortality. Because of this, the western United States is
facing one of the highest wildland fire threats in history.
How do we cope with wildland fires?
Protecting lives and property from wildland fire can be a relatively
easy task, with a little education and planning. Fire-resistant roofs,
vegetation-free safety zones around buildings, adequate water supplies,
and planned escape routes can greatly improve the likelihood of
surviving a fire with minimal loss. Of course, building in areas not
prone to wildland fires can also significantly reduce the threat of
these natural hazards. Since fires most frequently occur during periods
of low precipitation, weather forecasting serves an important role in
fire mitigation by alerting fire protection agencies and citizens of
future dry periods. In the western United States, the National Forest
Service, state agencies, county agencies, and local municipalities have
dedicated fire fighting teams that control wildland fires and protect
property during fire season. During the low-risk season, these teams
perform prescribed burns to reduce future wildland fire risk. Satellite
imagery is used to assist wildland fire fighting efforts by identifying
areas of diseased or dead trees that may be difficult to detect from
the ground. The U.S. government spends hundreds of millions of dollars
annually to control wildland fires.