The head of a Maine timberland company who has been active in sustainable forestry issues for decades has been named chairman of the board of directors of The Nature Conservancy.

Roger Milliken Jr., president and CEO of the Baskahegan Co., has served eight years on the national board of The Nature Conservancy, which is one of the largest and best-known conservation organizations in the world.

Milliken, who has also spent a decade on the board of trustees of the organization’s Maine chapter, is taking over a position formerly held by Treasury Secretary Henry Paulson and most recently by John Morgridge, former president and CEO of Cisco Systems Inc.

Milliken, of Cumberland, has headed the Baskahegan Co. since 1989 and has earned a reputation in Maine and nationally for his work to balance forest economics with environmental concerns. Baskahegan Co. owns more than 100,000 acres of forestland in eastern Maine. All of the company’s lands have been certified as being managed sustainably by the Forest Stewardship Council.

He was a key player in the development of Maine’s Forest Practices Act nearly 20 years ago and had a major role in the debate over clear-cutting in the late 1990s. Milliken is past president of the Maine Forest Products Council, served on the Land for Maine’s Future board and chairs Manomet Center for Conservation Sciences’ forest conservation program.

Milliken could not be reached for comment Tuesday. But in a statement accompanying The Nature Conservancy’s announcement of its new board chairman, Milliken said he was thrilled to be taking the helm at such a critical time in the organization’s history.

“With the Conservancy’s global perspective and local presence in 50 states and more than 30 countries, the organization is well positioned to tackle global threats like climate change, and help protect the natural systems around the world that sustain all life,” he said.

The Nature Conservancy has long had a presence in Maine but has emerged as a major player in conservation efforts during the past decade.

The organization bought 180,000 acres of forestland along the Upper St. John River in Aroostook County in the late 1990s and protected more than 240,000 acres near Mount Katahdin. The organization has also been heavily involved in other Maine conservation projects as well as the proposal to remove two dams and bypass a third in the Penobscot River.

The Nature Conservancy also negotiated a land conservation agreement with Plum Creek Timber Co. and two other conservation groups to protect more than 340,000 acres in the Moosehead Lake region. That $35 million deal is contingent on state regulators approving Plum Creek’s housing and resort development plan.