Maine Coast Heritage Trust said Wednesday it is launching a campaign to raise $100 million over the next five years to protect Maine land.

The group already has received pledges for $50 million in what is believed to be the largest land protection fund-raising effort in state history.

Since 1970, the group has preserved 110,000 acres, including 240 coastal islands. Recent acquisitions include Beech Hill in Rockport, Jordan’s Delight in Harrington and Cow Island in Portland.

The money is needed to allow the group to act quickly to acquire coastal property, which is increasingly in demand for development and commands higher and higher prices, trust officials said in announcing the capital campaign during a news conference in Portland.

Open space in Maine is disappearing at a rate of 100 acres per day, the group calculates. That, coupled with the fact that the populations of Maine’s coastal communities are growing three times faster than the state average, means that popular shore access points and ocean views are disappearing almost daily.

The trust cites as an example a housing development long planned and long fought on what is known as Munroe Field along U.S. Route 1 in Lincolnville that offers a commanding view of Penobscot Bay.

The group hopes to raise money to preserve what it views as such gems along a coastline that generates 80 percent of the $2.7 billion in tourist dollars generated in Maine each year.

“With growing numbers of people seeking their own piece of the coast, land values are skyrocketing,” said Jay Espy, president of the trust. “The combination of these trends threatens to erode what many people cherish about Maine’s coast – its natural beauty and traditions.”

In an example of preserving tradition, the trust worked with local residents to preserve Frenchboro, an island south of Mount Desert Island. When a 940-acre parcel on the island went up for sale for $3 million in 1999, Frenchboro selectmen contacted Maine Coast Heritage Trust and the Island Institute, which asked for help in preserving the land and way of life of the island’s 45 inhabitants, many of whom are fishermen.

Island residents feared that the parcel, which covered about three-quarters of the island, would be sold for development, changing their fishing community into one in which they would become caretakers of seasonal homes.

The trust, the Island Institute and Maine Sea Coast Mission worked with local residents to raise the $3 million asking price in less than nine months. It was the largest amount of private money raised for an island conservation effort in Maine.

In the end, the property was preserved with its shoreland kept open to the public. In addition, a plan was developed to allow for future development of the village of Frenchboro, compensate the town for lost tax revenue, restore the island’s historic schoolhouse, church, parsonage and museum, and secure a pier that will provide access to the working waterfront.

Gov. Angus King lauded the project last year. “The project serves as an example of how communities can take charge of their future, building alliances and working collaboratively to foster conservation and community development,” he said.

To ensure more stories like Frenchboro, the trust wants more readily available money to act quickly when the for-sale sign goes up.

Of the $100 million it hopes to raise, 75 percent will be devoted to land protection. The remaining money will be added to an existing endowment and used to care for property the trust already owns.

In the past year, the group has been talking quietly with “major, major” donors, said David MacDonald, the trust’s director of land management. At a meeting with the Bangor Daily News last week, he said the group already had received pledges for $50 million, much of it from summer residents. The campaign is chaired by Richard Rockefeller, a Falmouth resident, who has a summer place on Bartlett Island off Mount Desert Island.

“We have become accustomed to campaigns of this size for universities, museums and libraries,” Rockefeller said Wednesday. “Until recently, we have not supported land conservation with campaigns of this magnitude. This I do not understand because, to me, the Maine coast is all of these things.

“It’s a university. It’s a museum, of sorts. It’s a library. And, it’s the place I go for inspiration,” he said.

Not everyone is so eager to see more of Maine’s coast land set aside as preserves.

Selectmen in Georgetown near Bath are debating what to do about the future of Merrymeeting Bay where development is gobbling up coastline but several conservation projects have taken valuable property off the tax rolls. Two recent projects that protected more than 350 acres cost the town about $12,000 in annual revenue as well as potential taxes from the 10 houses that could have been built on the properties.

MacDonald of Maine Coast Heritage Trust said his group tries to address these concerns by looking for creative ways to make payments in lieu of taxes.

In recent times, people have been willing to donate money to land conservation efforts.

Earlier this year, well ahead of schedule, The Nature Conservancy reached its goal of raising $50 million to protect lands across Maine, including the headwaters of the St. John River. More than two years ago, the group bought 185,000 acres of timberland, including 40 miles of rivers, from International Paper Co. for $35 million. It was the largest conservation purchase in the Northeast and the biggest project the conservancy had funded.

The Maine group borrowed the money from its national parent organization and set about raising the sum to repay the loan. In February 2000, the conservancy decided to raise $50 million over five years in order to pay back the loan as well as protect additional areas involving the Saco River, Cobscook Bay and the Camden Hills.