ST. MARYS, Pa. -- Deep forests straddling the Eastern Continental Divide are home to the largest elk herd in the northeastern United States. Soon, they will hold the state's largest conservation easement.

The Nature Conservancy will spend $5.5 million to buy that land-preservation designation on almost 10,000 acres of the "Elk Timberlands," where black cherry, red oak and beech trees prop up the sky and creeks holding native brook trout babble through hemlock hollows.

Benefiting from the designation will be the elk, deer, black bear, beaver, bobcat and coyote that live there because the easement on four jigsaw-puzzle-type pieces of hardwood forest land will preserve forever one of the East's largest remaining open spaces.

Hunters, fishermen, birdwatchers and hikers likewise should be thrilled because the timbered but otherwise relatively unspoiled wildlife habitat, much of which has been privately owned and posted "no trespassing" for generations, will eventually be opened for public recreation.

And local government officials and forest-industry workers are smiling because unlike many other public land-preservation efforts, the property will continue to be timbered by the new owners and remain on the tax rolls.

"I hope people see this as a good marriage of conservation and timber production and a progressive transaction that is pretty much a win-win across the board," said Ken Kane, a forester with Keith Horn Consulting Foresters, which managed the properties for 25 years and helped set up the April sale.

The Elk Timberlands acreage was purchased for $32 million by Conservation Forestry, a timber investment company based in New Hampshire, from longtime owner Kaul and Hall Oil and Gas Co., of St. Marys. A timbering business owned by the Kaul and Hall families had more than 100,000 acres and was one of the biggest in the state until 1921. At that time, the company closed its St. Marys sawmill because there were no trees left to cut due to the unsustainable forestry practices of those times.

"I've spent a big part of my career doing restoration forestry, trying to fix damage done to the forest, and my thoughts on this were to keep it a sustainably managed forest, keep it on the tax rolls and maintain the unique habitat for elk and other wildlife," said Mr. Kane, who will continue to manage the properties for Conservation Forestry.

"The Elk County planning officer, when I explained how this will work to him, was ecstatic because this is what we need in Elk County. We don't need someone buying land here, cutting the hell out of it then spinning it off to the state."

The $5.5 million conservation-easement agreement between The Nature Conservancy and Conservation Forestry allows the company to timber the properties but imposes conservation restrictions on all of the acreage. For example no timbering will be permitted within 300 feet of streams, and Mr. Kane is reapplying for sustainable forest management certification, which the land had until 2005, from the Forest Stewardship Council.

"This was an exciting project for Conservation Forestry and a great example of how private capital and conservation capital can leverage each other's goals," said Ken Gulges, of Conservation Forestry. "We will continue to manage this forest to produce high-quality timber products that will flow into the regional economy."

Todd Sampsell, director of conservation operations for The Nature Conservancy, said the conservation easement keeps land in private ownership while preserving certain public rights for access and sustainable management of the timber forever. The conservancy plans to annually monitor the timber harvest and other land uses, including oil and gas drilling on a handful of existing and potential well sites, to ensure compliance with the easement and with best-management practices.

"The price for that protection works out to about $500 an acre," Mr. Sampsell said. "If we'd tried to buy the land, it would have been cost prohibitive."

Mr. Sampsell said the property's value stems from its location in a stretch of the Appalachians between state-owned forests in north-central Pennsylvania and the Allegheny National Forest to the west.

The Nature Conservancy, one of the world's largest nonprofit environmental organizations, measured by member numbers and acreage protected, is known for working with landowners such as farmers, ranchers and timber companies to advance mutual goals.

Mr. Sampsell said the Elk Timberlands project is the first by the conservancy in Pennsylvania. But it has used conservation easements to protect more than 1 million acres in Wisconsin, Tennessee, New York, Maine and throughout the Southeast. A recent easement in Montana protected 350,000 acres.

The Elk Timberlands acreage is a significant addition to the 176,000 acres of land in Pennsylvania already protected by conservation easements, said Andy Loza, executive director of the Pennsylvania Land Trust Association.

"It's great stuff," Mr. Loza said. "Not only does such an easement serve the land but it also keeps it in productive private use. We could use more of them."

The Nature Conservancy has a year to complete its purchase of the Elk Timberlands easement. The conservancy is conducting fundraising to pay for the easement and monitoring and management costs. It has already received about $4 million from private donations and foundations. It's also applied for a $2 million grant from the state Department of Conservation and Natural Resources.

DCNR Deputy Secretary Cindy Dunn said the department doesn't have money to acquire more public land itself but likes the Elk Timberlands project as a way to promote the public's desire for land conservation while preserving the local forestry-based economy.

"This is a good model. It guarantees sustainable forestry and practices into the future, and if you work in the industry, that's good," Ms. Dunn said. "But it also provides for conservation of public values, like clean water, good hunting and fishing areas.

"There's still strong public support for land conservation, and this project puts to bed the myth that conservation easements put land off limits and damage the local economy,"