Last month's fire in Los Alamos, New Mexico, burned close to 50,000 acres and destroyed more than 200 homes. This fire was a prescribed fire set by the U.S. Forest Service (USFS), but the fire quickly burned out of control. Why did the USFS light the fire?

Fires set by lightning have always shaped wildland ecosystems. The occasional fire burned unchecked until it ran out of fuel or was doused by rain. The fire opened up the forest canopy, letting in more light. It also cleared undergrowth, allowing new plants to grow. After a major fire, different plants and animals often repopulated the burned areas, bringing biodiversity to the forest. Some plant species even depend on fire to germinate their seeds.

During Neolithic times about 9,000 years ago, the first farmers controlled fire well enough to use an agricultural technique called slash-and-burn cultivation. They burned fields to clear away brush and trees and to produce fertilizer from the ash. This practice is still used in many tropical areas around the world today.

About 100 years ago, the U.S. National Park Service adopted a policy to suppress all wildland fires. Whether a fire was ignited naturally by lightning or accidentally by man, firefighters would extinguish the fire as quickly as possible in order to protect the trees and nearby property. But without any fire to clear the twigs, branches, and brush, serious undergrowth began to build up. This abundance of natural fuel could turn a wildland fire into a major catastrophe—a dangerous wildfire that is difficult to control.

For a discussion of the role of forest fires in the ecosystem of the great sequoia forests, read Saving the Sequoias.

In recent years, fire officials have revised federal wildland fire management strategies. The new strategies call for allowing natural fires to burn in a controlled way and for setting fires intentionally in order to clean out undergrowth. The expectation is that these smaller fires can help prevent situations in which lightning ignites extremely large fires that burn out of control, causing damage to the wildland ecosystem and human property. The U.S. Forest Service has proposed a set of guiding principles for all agencies that have wildland fire policies. Some of the key points are:

• Protection of human life is the first priority in wildland fire management.
  
  
• Property and natural/cultural resources jointly become the second priority.
  
  
• Wildland fire as a critical natural process must be reintroduced into the ecosystem.
  
  
• Where wildland fire cannot be safely reintroduced because of hazardous fuel build-ups, some form of pretreatment must be considered, particularly in wildland/urban interface areas.
  
  
• Every area with burnable vegetation will have an approved Fire Management Plan.
  
       (Source: USDA Forest Service)

Not everyone agrees with the policy of prescribed fires. Critics claim that any fire—even a prescribed fire such as the Los Alamos fire—can get out of control and pose a risk to human life and property, and therefore efforts should be made to suppress all fires. Others claim that prescribed burns contribute to air pollution and that they destroy timber that could be harvested for lumber.

Both sides of the argument agree that the forces of nature will ultimately prevail over human schemes. Those in favor of fire management see their policies as returning ecosystems to their most natural state. Those in favor of fire suppression perceive their policies as the best route to protecting human life and property.

• Read an article about the 1988 fires in Yellowstone National Park. List three things that were positive about the fire and three things that were negative about it.

• Do you think that the "Let It Burn" policy was a good one? Explain your answer:

Wildland Fires 2000
You can view a table of this year's wildland fires to date, including geographic area, number of wildfires, and number of acres burned. As of the beginning of June, there were wildfires burning in six states. Read about them in CNN's article: "U.S. contends with especially fiery year."

New Mexico is suffering from a second major fire, burning in the Sangre de Cristo Mountains near Pecos. Nearby, the area affected by the Los Alamos fire faces a new risk of flooding. The trees, shrubs, and grass on the mountains in the area normally control runoff. This year these runoff barriers have been turned to ash. Homes that survived the fire now face the possibility of flooding and mudslides as the rainy season begins in July.

• Read the article: "First fire, now flooding: Los Alamos waits for the mountain to come down."

Florida has also been badly hit by wildland fires. The state is suffering from a drought, with very dry conditions, low humidity, and lots of wind. These conditions spell disaster to the fire department. About 140 fires erupted over Memorial Day weekend alone. Most of them have been suppressed, but several major ones continue to burn. The following weekend, an additional 29 fires broke out across the state.

• Read about the Florida fires: "Storm over Florida could worsen fires plaguing drought-stricken state."
  
  
• Read the Riverdeep Today article about drought across the nation, "U.S. Drought Continues?"

Learn More

Chemistry students: Study the role that lightning plays in atmospheric reactions during a thunderstorm in the Chemistry Explorer activity, Energy Directions.

• What ingredient does lightning contribute to the chemical reactions in the atmosphere and to wildland fires? (Hint: What three things are required for a fire to burn?)

More Links

• Firewise: This site offers information about fireproofing homes that are close to wildland areas (woody areas, parks, and mountains).
  
  

• Fire in the National Parks: This brief guide from the National Park Service explains fire's role in natural areas.