Twenty-eight acres of woodland that had long been part of a private Matinecock estate will be open later this year to the public for hiking, birding and other activities.

The Old Westbury-based North Shore Land Alliance purchased the land last week with $4 million donated by Verena and Roderick H. Cushman, who live nearby part of the year, said alliance president Lisa Ott.

It’s the largest single contribution in the conservation group’s 13-year history, she said.

Some of the trees on the land are hundreds of years old, and the forest is critical habitat for a number of species of birds, as well as foxes and other wildlife, Ott said.

“It’s been undeveloped natural land throughout its history,” she said.

Decades ago, trails were created on the land as part of a fox-hunting route. Those trails need to be cleared of fallen trees. After trails are ready and a small parking area is built, the alliance will open the land for public use, likely in the fall, Ott said.

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The former estate, which had been owned by Colleen Simeone, was 35 acres, she said. The remaining 7 acres, which includes the home, were bought separately and not by the alliance, Ott said.

Without the alliance’s conservation of the 28 acres, there was a risk that a number of homes would have been built on the land, she said.

Leaving the land free of homes and other impervious surfaces — such as driveways and patios — means rainwater will still be able to soak through the soil to help recharge the aquifer that supplies drinking water to much of Long Island, she said.

In neighboring Upper Brookville, the alliance is helping finalize an agreement that would preserve 53 of 97 acres for open space and allow as many as 13 homes on the rest of the land. In that arrangement, the alliance would hold stewardship over the open space under a perpetual easement, Ott said.

Lisa Ott, President of the North Shore Land Alliance, right, Jane Jackson, Director of Stewardship, center, and Stephen Searl, Director of Conservation, left, view the 28 acres of land recently purchased in Matinecock for preservation, Wednesday, June 22, 2016. Photo Credit: Steve Pfost

The alliance has bought or helped facilitate the purchase of 1,060 acres of land for conservation.