[JOAN CARTAN-HANSEN] Fire is a chemical reaction. You need three things for a fire: oxygen, fuel and heat. It's called a fire triangle. Combine the elements of the triangle and you get fire. Eliminate just one and the fire goes out.

That's what firefighters try to do. They use water or chemicals to cool the fire or eliminate the oxygen. They remove the bushes, trees or groundcover to limit the fuel

Sometimes firefighters use a back burn to stop or direct a fire. They set a controlled blaze and burn the area in the fire's path. That eliminates the fuel so the fire doesn't have anyplace to go. Sometimes land managers set a prescribed fire on purpose or let a naturally started fire burn. But however it starts the idea is the same.

A prescribed burn may reduce the chance of a wildfire later on and that's what land managers worry about - a wildfire. It's a blaze that's out of control. It can be in a forest or a rangeland and wildfires can be very scary. They create their own high winds and those high winds can push the fire further and faster burning everything in its path.

Wildfires spread in three patterns: A ground fire burns the material in the soil beneath the surface. A surface fire burns fallen branches and other materials on the ground and ground fires burn the top layers of the trees. Ground fires are the hottest and most difficult to control. Today's firefighters use a lot of science to do their job. They need to know what the weather will do, they need to know what kinds of plants or fuel are in the path of the blaze and they need to know the geology and topography of the land. Firefighting isn't an exact science. Sometimes there's just no stopping a wildfire.

Scientists play an important role after the fires too. Charred land can erode or wash away because there's no ground cover left to protect the soil. Noxious weeds can crowd out native plants so soon after a fire land managers help rehabilitate the burned area by planting seeds and using other landscaping techniques. Fires are an important part of our ecosystem. Some trees like the lodge pole pine actually need fire to open up their cones and release their seeds. So wildfires have a good and a bad side and it's a scientist's job to learn how to use fire to improve our land and how to keep it from destroying something precious.

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