The nation's vast publicly owned forests, the last redoubt of serenity in a clangorous world, have suddenly become a battleground, pitting conservationists against a timber industry emboldened by last November's election results.

Senate Republicans, led by two key committee chairmen, are rushing through an industry-supported bill that could, in effect, prevent the designation of any more "wilderness" areas -- those areas protected from development and exploitation.

The bill would open eastern forests to further development by Jan. 1, 1983, if Congress has not designated any of those areas as wildernesses by then. A Jan. 1, 1985, deadline would apply to western forests. Time is the key, and time -- given how much of that it takes to complete studies on wilderness areas and push the designations through Congress -- is on the side of the pro-exploiters.

The bill also would prohibit the Forest Service from considering any of its lands for wilderness designation without specific congressional authorization.

Hearings last week at the Senate Energy and Natural Resources Committee produced bitter exchanges between GOP senators and conservationists, who charged that the legislation would negate compromises crafted carefully in recent years between them, the industry and the U.S. Forest Service.

In a sharp reversal of executive policy, the Department of Agriculture last week came out strongly in favor of the bill, introduced by Sen. S. I. Hayakawa (R-Calif.). Deputy Secretary Richard E. Lying said a key concern is the consequences wilderness designation may carry for the administration's plans for more exploitation of public lands.

Main cosponsors of the bill and supporters of the more-exploitation approach are Sens. James A. McClure (R-Idaho), energy committee chairman, and Agriculture Chairman Jesse A. Helems (R-N.C.), whose latest campaigns got at least $19,200 from forest and paper industry political action committees.

The crux of the debate is the timber cutters' complaint that the slowness of wilderness-designation procedures is hampering their planning and operations to such a degree that the national economy is imperiled.

That agrument has found a sympathetic ear in the GOP-controlled Senate, but the conservationists' charge of political "fix" has touched raw nerves. During two days of hearings, Sen. Malcolm Wallop (R-Wyo.) repeatedly lectured witnesses for "anti-intellectual" behavior, for "hysterical" and inflammatory rhetoric.

Most observers believe the Hayakawa bill will have smooth sailing through the Energy and Agriculture committees. It could, however, encounter trouble in the House, where environmentalists still have a few friends in positions of influence.

Today's fight goes back almost a decade to 1972, when the Forest Service began a review of roadless lands in the 190-million-ace national forest system, to determine which portions Congress should designate wilderness and which should be opened to development.

That process, called RARE I, was held by a federal court to be too cursory and in 1977 the USDA's Forest Service, then controlled by the Carter administration started a new review. That was called RARE II, and its recommendations went to Congress in 1979.

RARE II held that 36 million acres of roadless areas could be opened for development.It recommended 12 million acres for wilderness -- that is, no chainsaws, no bulldozers, no log chains -- and put 15 million acres more in a "further planning" category.

A vital element in all of this politics. On the theory that no one knows nature better than a politician, Congress retained the powers of wilderness designation. Last year it adopted RARE II wilderness recommendations for Louisiana, New Mexico and Colorado, among other states.

Through it all, the forest industry, whose welfare depends heavily on the purchase of timber on public lands, was a reluctant compromiser. Its complaints got action from the Carter administration; its lawyers engineered House-adopted language last year to streamline forest-management procedures.

Then in November, with Republicans taking over the Senate and the White House, the tone changed. All agreements were off. An industry leader, John Crowell, was named assistant secretary of agriculture -- chief overseer of the forests. Three weeks after it was introduced, Hayakawa's bill was undergoing hearings.

Hayakawa's bill has been roundly denounced by the major conservation and environmental organazations. "The most radical anti-wilderness bill yet introduced," Sierra Club president Joe Fountaine called it.

"There's a problem and it doesn't help to be wise about it. . . . I hope you would come off of your high horses," Wallon scolded the critics. "I wish you at the [witness] table would tone down your rhetoric."

"I will agree to drop the rhetoric if you drop the bill, said William A. Turnage, executive director of the Wilderness Society.

Obviously, it was no deal.