CRAWFORD, Texas -- President Bush is expected Thursday to announce changes in federal rules that would speed up selective logging in national forests, embarking on a course intended to help prevent the kind of destructive fires that have plagued Western states this summer.

But environmentalists are complaining that the government is upending decades of regulations and that the White House is using fear of fires to cut down trees that are old but healthy, and fire-resistant, from back-country forests.

Details of the plan have not been made public. But interviews with U.S. Forest Service officials, other administration officials and environmentalists shed light on its likely elements.

Formulating what one senior official called a "new approach to major issues" affecting the management of public land, Bush is expected to propose removing administrative barriers to cutting timber from fire-prone forests by streamlining environmental reviews required before timber harvest can begin.

The plan would make it harder for environmental groups, citizens and Forest Service employees to appeal logging plans. The timber industry views such measures as necessary to protect forests.

Bush is flying Thursday from his ranch in Central Texas to one of southern Oregon's most fire-troubled areas near the border with California to make the announcement. Oregon and California are among several states that have suffered catastrophic wildfires this season.

The plan would make it easier to get approval to thin underbrush and small noncommercial trees as well as "thinning out some commercial-grade wood" in areas at high risk of fire, a senior administration official said.

It is built around restructuring the rules that govern appeals of federal decisions affecting the environment, making the National Environmental Policy Act less cumbersome. The measure has regulated governmental environmental action for three decades.

A senior administration official emphasized that the plan was not intended to open the national forests to "wholesale commercial logging" but rather to remove the most flammable wood in the forests.

If the choice is between thinning the forest and putting entire ecosystems at risk, he said, "some thinning is the way to go."

He said the plan is built around a 10-year strategy adopted in May by administration officials, 17 governors from both parties, local and tribal officials, academics and environmentalists to seek consensus on the treatment of federal forests.

It will involve both changes in regulations, intended to make federal agency environmental rules more consistent with each other, and greater consideration for the effect logging would have on animals and other plants earlier in the process. Some changes will require congressional action.

Reflecting the need to win approval of the House and Senate and foreshadowing lengthy political fights to accomplish the full goals Bush is likely to outline, a senior forest official said: "My gut tells me if we could have done them on our own we would have done them.... We can't do it without going to Congress."

Adding that greater attention is needed to the dangers that lurk in forests in which brush, dead trees and other fuel have been allowed to build up, he referred to the current rash of fires and warned: "We could have many, many years just like this."

But environmentalists argue that the administration is using the fires as an excuse to reach for much broader changes.

"We're all stuck on fires right now, but the Bush administration is talking about changes in environmental law on the books since 1970," said Susan Ash, wilderness campaign director of the Oregon Natural Resources Council, an environmental group.

But, said Chris West, a vice president of the American Forest Resource Council, a timber industry group: "We've burned up half a million acres of Oregon's forests. It's high time the federal government began to seriously address concerns about the health of Western forests."

By delving into the forestry issue, Bush is entering an area of great political sensitivities in Oregon: In the most populated regions of the state, around Portland, there are strong environmental sentiments likely to oppose measure to promote logging. But pollsters report that in the rural areas more economically dependent on the forests, support grows for more aggressive logging.

With unemployment above 7%, Oregon has consistently been one of the states with the highest rate of joblessness over the last year. The timber industry, once the top source of employment, has been passed by the high-tech industry as the state's biggest provider of jobs.

Bob Moore, a public opinion researcher who conducts polls for Republican candidates as well as timber concerns and utilities, said that concern about forest fires had grown so great that "any action [by Bush] is going to be seen as potentially helpful."

"The feeling is a lot of ground is being burned and the federal government hasn't done anything about it."

Timber sale appeals and court rulings have played a major role in shaping Forest Service policy in the last 15 years. Logging levels fell sharply in the Pacific Northwest in the wake of court rulings to protect the northern spotted owl habitat, and environmental groups have used timber sale appeals to modify or sometimes halt logging plans they believe violate environmental laws.

Limiting those reviews would require congressional action and would erode a fundamental right of the public to play a part in management of public lands, environmental activists complained.

"If what they're going to do is waive our environmental laws, it's going to take congressional action to do it," said Marty Hayden, legislative director of Earthjustice Legal Defense Fund.

"If you eliminate appeals and judicial review, you've largely taken the public out of having a meaningful role in the process," Hayden added. "Without the avenue to hold government accountable to play by the law, then what you're left with is, 'Thank you very much for your input. We'll get back to you later.' "

In 1995, after a series of wildfires, Congress waived environmental reviews of sales of salvaged timber across the country for 18 months.

"It caused the reemergence of timber wars in the Pacific Northwest that had started to quiet down," Hayden said. "The controversy ... far overshadowed anything it accomplished. Its legacy still haunts the Forest Service today, and I think Congress will be less inclined to do that kind of sweeping waiver."

Today several major environmental groups are calling for the Forest Service to direct the bulk of its fire prevention efforts and funding to land bordering houses and towns.

"Let's put the money where it does the most good," said Sean Cosgrove, national forest policy specialist for the Sierra Club.

Under a seven-point plan they are releasing in Oregon, the Sierra Club, Wilderness Society, Oregon Natural Resources Council and other groups are urging the Bush administration to spend $10 billion over the next five years to protect communities and homes from wildfire.

National fire policy emphasizes community protection, but a great deal of forest thinning is underway outside of community zones. Reviewing current forest spending in California, for instance, The Times found that national forests in the most remote parts of Northern California were receiving the most generous budgets for fuel reduction projects, with the least going to forests near urban areas.

Gerstenzang reported from Crawford, Shogren from Washington and Boxall from Los Angeles.