WASHINGTON — The Biden administration is moving to restore full environmental protections for Tongass National Forest in Alaska, reversing an attempt by former President Donald J. Trump to introduce logging and mining in pristine sections of one of the world’s largest intact temperate rain forests.
The move, announced Thursday by the Agriculture Department, comes a month after the administration gave notice it would “repeal or replace” a rule promulgated under Mr. Trump to open about nine million acres, or more than half of the forest, to development. That rule had stripped away protections that had been in place since 2001.
The Biden administration’s Tongass strategy includes a new safeguard: an end to large scale logging of old growth timber across the forest’s entire 16 million acres.
Alaskan lawmakers hoped that the administration might restore protections to some parts of the fragile forest but leave a portion open to logging and other activities.
But in a statement Thursday morning, the Agriculture Department, which houses the United States Forest Service, wrote that it is restoring the full protections to return “stability and certainty” to the fragile forest.
The vast wilderness, in southeastern Alaska, is home to more than 400 species of wildlife, fish and shellfish, including nesting bald eagles, moose and the world’s greatest concentration of black bears. Tucked between its snowy peaks, fjords and rushing rivers are stands of red and yellow cedar and Western hemlock, as well as Sitka spruce trees that are at least 800 years old.
The Biden administration’s Tongass plan also includes $25 million in federal spending on local sustainable development in Alaska, for projects to improve the health of the forest.
That money appears designed in part to appease Republican Senator Lisa Murkowski, of Alaska, who is now playing a key role in negotiating the bipartisan $579 billion infrastructure bill that President Biden sees as crucial to his economic agenda. She had personally asked senior administration officials to leave open portions of the Tongass for economic development.
“Obviously, my strong, strong preference has been, for an exemption, that this roadless rule should not be for the whole nine million acres,” Ms. Murkowski said in an interview last month. “We feel like we’re kind of beating our heads against the wall from the policy perspective, from the people that live there in these small communities that are trying to figure out what their economic opportunities might be.”
Alaska’s other Senator, Dan Sullivan, also a Republican, called the $25 million “a pay-off for killing sustained economic development opportunities in Southeast” by “further starving our timber industry of supply.”
Mr. Biden is seeking to enact the most ambitious climate agenda envisioned by an American president. As record drought, wildfires and heat waves hobble Western states, Mr. Biden is aiming to revive and strengthen protections rolled back by Mr. Trump and cut the pollution that is driving climate change.
This fall, Mr. Biden plans to attend a United Nations conference of world leaders in Scotland to argue that after four years in which the American president mocked climate science, the United States is a leader in the fight against global warming.
Environmentalists said the move to fully restore protections to the Tongass could be one step in making that case.
“This is the Biden administration putting itself squarely on the road to reclaiming climate leadership, as it heads to the Glasgow summit this fall,” said Niel Lawrence, Alaska director of the Natural Resources Defense Council, an advocacy group.
The forest plays an important role in protecting the climate. Scientists point out that the Tongass benefits billions of people across the planet who are unlikely to ever set foot there: It is one of the world’s largest carbon sinks, storing the equivalent of about 8 percent of the carbon stored in all the forests of the lower 48 states combined.
Much of that carbon is locked away in five million acres of old-growth trees, spread across the forest. Many of those trees have been absorbing atmospheric carbon for more than 1,000 years.
For that reason, scientists also praised the administration’s new move to end large scale logging of old-growth timber in the Tongass, even in sections that are not subject to the new protections limiting road construction and other development.
“Under the Trump plan to log that old-growth forest, we would have been emitting the carbon equivalent of putting 50,000 new vehicles on the road per year,” said Dominick DellaSala, a scientist with the Earth Island Institute, a nonprofit environmental organization. “So now the forest is doing its best role, which is to protect the climate. The Tongass is North America’s lungs.”
Native American tribes that claim the forest as an ancestral homeland applauded the restoration of protections.
“This is one of the first steps that we have seen towards the racial equity that was promised toward our Indigenous communities from the Biden administration,” said Marina Anderson, administrator of the Organized Village of Kasaan, in Ketchikan, Alaska.
“We have a lot on the table — the forest is everything to us,” she said. “Everything that we’ve ever used or created comes from the forest: our methods of transportation, our tools, our weapons.”
Republicans and Democrats have fought over the Tongass for 20 years. The forest was heavily logged in the 1960s and the 1970s, but in 2001 President Bill Clinton enacted the “roadless rule” that blocked road construction necessary for logging and mining in much of the forest.
Just three months before leaving office, Mr. Trump exempted the entire forest from the “roadless rule,” handing a victory to Alaska’s Republican leaders who argued that the southeastern part of their state needed the economic boost that logging and other development would bring. The move was assailed by environmentalists and the majority of commenters who formally registered opinions with the government.
However, no new logging or construction has taken place in the forest in the interim. That is in part, experts have said, because it was widely expected that Mr. Biden would restore the protections soon after he took office.
It remains possible that a future Republican administration could lift the protections once again.
Ms. Murkowski said the yo-yo aspect of policy regarding Tongass is difficult for Alaskans.
“This is hard on the communities, it’s hard to plan,” she said. “There’s a local bank that’s based down there that’s catch as catch can, you know. How do you know where you’re going to go for investment when you have such uncertainty that’s been going on for so long? We’ve got to try to put a stop to this.”