Exhibits: Nature: Wildfire
A Force of Nature
In the summer of 2000 a vacationing family stood at Lemhi Pass near the Idaho-Montana border. The pass, where the Lewis and Clark expedition first looked upon the vast Columbia River watershed, is a place of stunning views. On that day the vacationers saw no view to stir their hearts and fire their imaginations, only a thick haze which obscured everything in the distance below them.
The cause of that haze was a wildfire burning several thousand acres of forest in the Frank Church- River of No Return wilderness thirty miles away. It was one of several large wildfires that erupted throughout the West during that summer. One of those fires caused the evacuation of Los Alamos National Laboratory in New Mexico, and images of a burning forest and burning houses in the town where the atomic bomb was born filled television screens across America. The whole nation became frighteningly aware of the powerful force of wildfires, and how close to home the threat has become.
To Build a Fire
Fires are part of the natural world and occur, when conditions are right, in every part of our country, indeed, in every part of the world. According to Greek mythology, the Titan Prometheus stole fire from the gods on Mount Olympus and gave it to humankind, but even an Olympian fire requires the same thing that mortal fires do: an interaction of heat, fuel, and oxygen.
The heat source-- be that a smoldering campfire, a carelessly tossed cigarette, or a bolt of lighting from Zeus-- is required for the initial ignition. Heat is also needed to maintain and allow the fire to spread. But heat alone is not enough: a fire also needs fuel, which can be any combustible material such as twigs, needles, or dead wood, and oxygen, which supports the chemical process that occurs during a fire. Without any of these ingredients, no fire is possible.
Fire plays an important role in many ecosystems; in fact, most ecological regions in North America were dependent to some extent upon fire. Many plant species have developed important adaptations that allow them to survive, thrive, and even require fire for survival. Fire triggers seed release in lodgepole pines and stimulates flowering and fruiting in some shrubs and herbs. Fire in tallgrass prairies burn accumulated litter and kill woody plants, allowing sunlight to reach. A grasslands fire also changes the soil?s nutrients so the growth of native grass species accelerates following fires. When fire is absent in a prairie ecosystem, woody shrubs and trees eventually replace grasses.
Different ecosystems accumulate and produce fuels at differing rates. Under natural conditions, fires occur at regular intervals: every two to three years in the ponderosa pine forests of the arid West, in five to ten year cycles in the prairies, 200-300 years in the lodgepole pine regions of the Rocky Mountains, 125-180 years in the jackpine forests around the Great Lakes.
This exhibit is sponsored by the National Interagency Fire Center.
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