by Whit Gibbons

November 4, 2007

Don't tell anyone from Southern California, but forest fires are not all bad. In fact, some can be good. If we had more forest management programs that did not intervene to keep fires from occurring naturally, we would not have some of the out-of-control fires we read about every year.

Unnatural fire control has been detrimental to natural systems whose flora and fauna have evolved to deal with periodic fires. But of course we typically measure the impact on what is detrimental to people. Forest fires have traditionally been classed as disasters when economic loss occurs. You might think I should say "when human lives are lost." But evidence suggests that Americans think of financial losses as being more important than the lives of plants, wild animals, or even people.

Consider the fire of October 8, 1871, that killed more people than any other in U.S. history--1,182. The Great Chicago Fire was on that date and resulted in what today would be equivalent to billions of dollars in economic loss. But the Chicago fire killed 250 people, not 1,182. The "forgotten fire" that killed over four times as many people began in Peshtigo, Wisconsin, 200 miles north of Chicago, on exactly the same day.

Both financial loss and human deaths from fires are tragic. Entire cities don't burn to the ground anymore, thanks to fire retardant construction materials, sprinkler systems, and efficient public safety departments. But vast forest areas can still be wind-whipped into infernos, and the underlying cause can often be found in improper forest management. In regions where fires occur frequently from lightning, nature is prepared for the consequences, which are usually fast burning, low-to-the ground, moderate-temperature fires. The dominant plants are fire-resistant or even fire-dependent. Jack pines in the upper Midwest depend on fires to open the seeds. Burning of the litter layer exposes mineral soil, optimizing seed establishment. A side benefit of a forest fire to young longleaf pine is the return of essential nutrients to the soil.

Native animals are also fire tolerant. Mortality of native wildlife during natural fires is generally negligible as species have adapted to living with periodic fire. Although a few individual birds, mammals, and reptiles may be killed in forest and prairie fires, overall population levels are seldom affected. Invertebrates may lose eggs and larvae, but recovery to normal population sizes is rapid.

Under prehuman natural conditions, fires traveled through forests frequently enough to prevent buildup of ground litter. Without firefighters or roads to retard their spread, some natural fires covered immense areas, eventually being extinguished by rain or a river barrier. Following a grass or forest fire, little or no flammable material remained in the form of dry grass, leaves, or pine needles. Future fires occurred from lightning strikes before a heavy buildup of ground litter and therefore burned rapidly and low to the ground. When such a cycle was established, fires were simply part of the natural environment, no more detrimental to wildlife than an occasional cold winter or major flood. In many regions, fire is a natural event, perceived only by humans as a disaster.

However, in areas where fire has been intentionally repressed for decades, the buildup of ground litter can be immense. This perfect fuel can lead to a hot and prolonged fire that is more likely to reach the tops of tall trees and develop into a crown fire. Many of today's hazardous forest fires occur in habitats that have been unnaturally protected from fire. One reason is that people complain about the smoke on highways and in neighborhoods resulting from "control," aka "prescribed," burning.

Generations of schoolchildren have been brought up with the wrong-headed notion that all forest fires are bad, primarily because of economic interests. But the threat of fire in forests with combustible material will always be with us. Perhaps homeowners who live near forests where natural fires are prevented need to stop complaining about the smoke when forestry programs want to use control burning to clear the forest of ground litter that collects. Complaints about a little smoke in the living room surely would not be as great as those about fires that engulf the whole house.

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