When Lewis and Clark explored the Northwest, the forests were relatively open, with 20 to 25 mature trees per acre. Periodically, lightning would start fires that would clear out underbrush and small trees, renewing the forests. Today's forests are completely different, with as many as 400 trees crowded onto each acre, along with thick undergrowth. This density of growth makes forests susceptible to disease, drought and severe wildfires. Instead of restoring forests, these wildfires destroy them, and it can take decades to recover. This radical change in our forests is the result of nearly a century of well-intentioned but misguided management. The effects of the decline in forests and rangelands are in the news each day. Fires are rampaging across the West. I recently took an aerial tour over the Hayman fire that ravaged Colorado. Words cannot describe the horrific devastation caused by the fire. The crisis threatens to worsen. Of the 470 million acres of federally managed forests, 190 million acres are at risk for catastrophic fires. With dense forests and severe drought, much of the West is a tinderbox waiting for a spark. Firefighters have effectively battled this summer's fires, in part because we have given them the resources to get the job done: more equipment, more intergovernmental cooperation and 4,000 more firefighters than just two years ago. As of last week, firefighters had contained 490 large fires and saved several rural communities from destruction. Fighting fires after they start, however, is not enough. We need to attack their root causes. On Thursday, President Bush is traveling to Oregon to see the damage caused by fires that have ravaged that state this summer. He will announce steps to accelerate our efforts to restore forest and rangeland health and reduce the long-term threat of these wildfires. Underscoring the president's plan is a basic philosophy: Restoring forest ecosystems will mean fewer excess fuels and fewer destructive fires. Prescribed burns and mechanical thinning are essential to achieving this goal. To facilitate this, we also need to make the thinning of small trees and undergrowth more cost-effective by awarding long-term contracts to private organizations. Similarly, this spring, Agriculture Secretary Ann Veneman and I reached an agreement with Idaho Gov. Dirk Kempthorne and Oregon Gov. John Kitzhaber on a comprehensive 10-year plan to actively manage lands at high risk for fire. That plan calls for regulatory changes to produce faster decisions on forest-thinning projects. For example, a 430-acre thinning project near Medford, Ore., involved six years, 830 pages of documentation, two environmental assessments and several lawsuits before work was allowed to continue. But where human lives are at stake, where property is at risk and where the forests and valuable wildlife habitat may be destroyed by wildfires, we simply cannot afford to wait. There are other practical steps citizens can take as well. People who choose to build homes in forests need to take sensible precautions. This includes building with fire-resistant materials, cutting back undergrowth and maintaining firebreaks. Firefighters make an assessment of each property to see what actions are needed to defend it. If homeowners have not taken simple steps to create defensible spaces around their homes, then firefighters should not be asked to put their lives on the line to protect their property. This summer's fires are destroying our forests and countless millions of dollars in property. Federal, state and local governments are spending billions of dollars to fight them. We can fight these fires now, but we also need to do more to restore forests and rangelands to their natural condition, which will prevent severe fires in the future. It's time to put the adage to work: An ounce of prevention is indeed worth a pound of cure. Gale A. Norton is the U.S. Interior secretary.