SOUTH KINGSTOWN — Clarkson Collins looked down from his second floor office window in the South Kingstown Land Trust’s Matunuck barn to admire the two-and-a half miles of rustic stone walls, all restored by volunteers, which ring the group’s 100-acre farmland.

Opposite that window hangs a map of land trust parcels — 150 sites, or more than 2,600 acres of preserved open space in South Kingstown, land that ranges from old meadows to thick forests. For 30 years, those acres have been monitored by volunteers, many being the same members who care for the stone walls and clear trails, research grants and host fundraising events.

“We love the land,” said Sophie Lewis, one of those volunteers.

Sunday those three decades of work will be celebrated during a Great Outdoors Celebration & Auction to be held from 4 to 6:30 p.m. at the barn, 17 Matunuck Beach Road.

But while this organization continues to open up beautiful South Kingstown vistas for all to enjoy, this Land Trust isn’t just about the land.

“Each land trust is unique,” said Collins, land management director. “When we preserve farmland, we are also preserving a way of life and a way of getting food to people, so in some ways we’re interested in preserving more than just the land itself.”

The Land Trust barn is a community resource, he said, often used by local groups, and host to land trust educational forums. Add to that, leased property is used by a busy community supported agriculture farm, and by a chef who grows fresh produce for his restaurant. The trust also helped preserve a Perryville grist mill and to re-establish a blight-resistant strain of the American chestnut tree.

It was more than 30 years ago that a local woman, Helena-Hope Gammell offered a parcel of her Perryville property and in the process, established the beginnings of this organization.

“The first papers were filed in February 1983,” said Collins, who joined the group during its initial year. Having spent summers in the Matunuck area during his boyhood, he appreciated the open farmland and meadows and so “by natural inclination I loved the idea of trying to preserve this land.”

As a teenager, he worked the same farmland he sees out his office window “and was just totally in love with the place.” That type of motivation inspires hundreds of other land trust members.

The South Kingstown Land Trust was founded as a private trust after public officials and researchers from the University of Rhode Island realized land use regulations were not sufficient to protect “the town’s open spaces, wildlife habitats, farm and forest lands, aquifers and recharge areas, and coastal ecosystems,” according to a 2007 forest management case study. In 1999, it incorporated as a private nonprofit corporation, with a mission to conserve, preserve and act as stewards of open space.

The 3.62-acre property the barn sits on was a gift from a private donor in 2001, Collins said. The barn building also was a gift from the same donor and opened in 2003.

It started out small and has been “a quiet organization,” said Joanne Riccitelli, land protection director, who works from the Wakefield office at 227 Robinson St., a place where residents can stop in and discover the group’s history.

“Farmers know who we are now,” Riccitelli said, “but other landowners might not know enough about us yet.”

There are 700 members, but the group hopes to expand membership. They have set a goal of 1,000 members, something they track with a chart on the window of the Robinson Street office. With the in-town presence, and public events such as Sunday’s auction and word-of-mouth information, residents, farmers and landowners are becoming more familiar with the group’s goals.

A great deal of effort is going into the auction, said Anne O’Neill, development director. Proceeds from the annual fundraising event have in the past provided more than 17 percent of the group’s operating expenses.

“Rent, salaries, lights and land protection are all part of it,” O’Neill said of the proceeds they hope come out of auctioning items such as a Sunday jazz brunch for four at the Ocean House in Watch Hill; or a cocktail party for 25 with a menu by Adair Catering.

Other auction items include two nights at the Vista Motel, Gloucester, Mass.; a moveable 16th century feast for six in a Kingston Colonial home; a one-week vacation in the Bahamas; a half-day on Narragansett Bay aboard a 35’ sloop; one week in Tuscany; and framed paintings featuring the work of artists Holley Flagg of Narragansett, Gregor Kammerer of Perryville, Joseph Keiffer of New York City who spent summers in South County, and Susan Shaw of Wyoming, R.I.

A solid budget is crucial to this organization because not only do landowners sometimes come to them with a parcel to sell, but also, Riccitelli “is always looking for property,” Collins said. She is assisted by various groups ranging from the town itself, to The Nature Conservancy.

Lewis and Collins agree, it has been 30 years of a lot of work, but it is worthwhile work.

“You’ve got to get out there and walk on the trails,” Lewis said. “They are beautiful.”