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Taming wild fires

Taming wild fires just a few clicks of the computer mouse can help scientists prevent wildfires to a great extent. To some, it may sound impractical, but is true. Computer simulations are being used by scientists to evolve ways to prevent forest fires. By combining satellite-derived vegetation data, topographic maps, weather data and ecological knowledge, scientists can now construct digital landscapes and experiment about ways to prevent fires that can destroy large patches of forests (www.science@nasa.com , August 28, 2001).

The technique has important uses for officials while deciding how best to tackle an ongoing blaze. These computer models can also be very helpful when it comes to taking decisions about how to prevent forest fires. Low-intensity fires are a normal characteristics of most forest ecosystems. Mature trees usually survive these fires. But if an area contains too much of deadwood and dry leaves, the top of the trees get ignited, starting a fire that is extremely destructive. The solution in such a situation is removing some of the deadwood and dry leaves from the area.

There are several ways to do this, such as controlled burns, selective logging or trimming low branches and underbrush. By using the computer models, fire-fighters don't have to guess the best choice. They can run simulations of each option and compare the results. "We can evaluate the effectiveness of a treatment over time because we can simulate the regeneration of the forests,' says Kevin Ryan, project leader for the Fire Effects Project, which is run by the Fire Science Laboratory of the us Department of Agriculture (usda) . In the case of prescribed fires, these simulations can be particularly important. "Fire managers are quite reluctant to set prescribed fires if they can't determine how they will spread,' says Steve Running, professor of forest ecology at the us -based University of Montana who specialises in remote sensing applications.

For land mapping, scientists have been using Landsat 7, a satellite of the National Aeronautics and Space Administration (nasa). The 30-metre-resolution maps produced by Landsat lay the foundation for the vegetation data fed to the simulators as they reveal the boundaries between forests, grasslands, deserts and cities. The computer-assisted approach to fire risk assessment is still relatively new and partially adopted, but the advantages of using computers have become widely recognised. "Simulating the fire behaviour on a computer is the future of planning efforts,' says Mark Finney, a forest researcher with the usda .