Fighting Future Fires

Flaring through parched timberland in the drought-stricken Pacific Northwest last week, the worst forest fires in more than half a century defied efforts to contain them. So far this year, some 1,800 fires have destroyed more than 105,000 acres of timber in Montana, Idaho, Oregon and Washington. Fire-fighting costs have climbed to $17 million; damage to the economy of Oregon alone is estimated at $5,000,000 a day. Because of the menace, most of the national forests in Montana, Or egon and Washington were closed to tourists and logging. President Johnson has declared Idaho a disaster area.

Ironically, there has been summer rainfall high over the Northwest. But the air temperature has been raised so much by an abnormally warm summer that the rain has evaporated before hitting earth. Lightning generated by these abortive rainstorms has continued to strike, setting fire to dried underbrush and causing an estimated 80% of the Northwest's fires.

Aerial Scanner. The U.S. Forest Service has mustered 11,000 men, nearly 100 planes and some 50 helicopters. But traditional techniques--dropping chemical fire retardants from planes, bulldozing swaths in front of fires, setting back fires, and simply shoveling dirt--have not been sufficient. It is be coming increasingly evident that if a blaze is not detected soon enough, is allowed to spread beyond a few hundred acres and is fanned by high winds, there is little that man can now do to control the flames.

Recognizing the difficulties of putting out huge fires, scientists at the U.S. Forest Service's Northern Forest Fire Laboratory, established at Missoula, Mont., in 1960, are concentrating on prevention and early detection techniques. Their most dramatic accomplishment to date is the perfection of an aerial infrared scanner that can detect fire in a small bucket in a forest 15,000 feet below. Installed aboard a Convair, it has been flown over areas recently struck by lightning and has already picked up 220 fires--which show up as white spots in an infrared photograph. Forest rangers discovered that many were merely cookfires at camp sites. But others were lightning-started blazes that could have turned into major conflagrations had they not been spotted and doused in time.

Computerized Flames. The scientists are also learning more about the habits of nature's arsonist, the lightning stroke. Their research tools include sensors for detecting electric-field charges, photoelectric devices for measuring luminosity, photographs and recordings of thunder. From studies of some 3,000 cloud-to-ground lightning flashes, two apparent patterns emerged: the number of lightning discharges from storm clouds seeded with silver iodide was from 32% to 38% less than from unseeded storms. One type of discharge, which lingers on the ground for a relatively long period of time (about one-fifth of a second)--appeared to be responsible for most fires. Thus, the scientists hope, cloud seeding and inspection of areas struck by long-discharge lightning, may some day reduce fires.

To aid in the development of fire-fighting techniques, the Missoula scientists use a combustion chamber and two wind tunnels to simulate a wide variety of fires. They also catalogue the kind of trees and underbrush that grow in each forest area, calculating the volatility of each and determining how fast it will burn under varying weather conditions. All of the data is being programmed into a computer that will eventually be used to print out a program tailored for an individual fire.

Eventually, the scientists hope to know enough about controlling the fires to be able to choose which to extinguish and which to let burn. Says Fire Laboratory Chief Arthur Brackebusch: "Fire has played an important role in building our beautiful wilderness areas. It has come through the forests harvesting, destroying old stands and making way for new ones. If we remove fire 100%, we may destroy rather than protect our wilderness areas."

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