The 366-acre Aquinnah estate known as Red Gate Farm - and described by the state Natural Heritage & Endangered Species Program as one of the most important tracts of land in the commonwealth - was the subject of a public hearing at the Martha's Vineyard Commission last week.

Property owners Caroline Kennedy and her husband Edwin Schlossberg have created a family subdivision for estate planning purposes. No building is planned at this time. The estate subdivision plan is under review by the commission as a development of regional impact (DRI).

Located between Moshup Trail and Squibnocket Pond, the property is home to at least a dozen protected species found throughout its windswept dunes, freshwater ponds, coastal heathlands and extensive pond and ocean frontage.

At the public hearing last Thursday night, former Vineyard Conservation Society executive director Robert Woodruff spoke in eloquent and almost emotional terms about the property. He described the elusive and threatened arethusa orchid and northern harrier, thousands of tons of sand that are moved by the wind every day, and beech and holly trees that are possibly more than 100 years old.

"I spoke to [Natural Heritage ecologist] Tim Simmons a week or so ago, and we talked about this property," Mr. Woodruff told the commission. "We both shook our heads in amazement at what we've been privileged to see."

Mr. Woodruff spoke in favor of the plan. "What the family has done in the past and will do in the future will be smart and right for the land, and the Island," he said.

The property has remained largely undeveloped since it was purchased by the applicant's mother, the late Jacqueline Kennedy Onassis, in 1978 from the Hornblower family for $1.1 million. At present only three homes exist on the entire estate.

The subdivision plan is unusual because the applicants are actually seeking to reduce the number of existing lots from more than 30 to seven. The plan was filed in November with the Aquinnah planning board, which voted to endorse it.

Richard Renehan, a partner at Goulston & Storrs in Boston who is representing the Kennedy-Schlossberg family, described the distinct nature of the plan to the commission. "This is not a building development plan," Mr. Renehan said. "It's an estate plan."

Mr. Renehan said the plan will ensure that the stewardship of the property is passed on to next generation of the Kennedy family. He noted that it will wipe from the books previous subdivision plans that existed for the property prior to the family's purchase - one that set out 150 lots, and another with more than 50.

The proposed estate plan will create a 100-acre lot surrounding the current family homestead, three lots ranging between 30 and 50 acres for each of the three teenaged Kennedy-Schlossberg children, two lots between 40 and 50 acres that will be available to sell if needed at a later time, and one 60-acre beach lot that will be forever unbuildable.

The plan also identifies building envelopes for any future development within the lots - restricting potential development to less than 15 per cent of the entire property and forever preserving more than 300 acres as open space.

Applicant Edwin Schlossberg attended the public hearing last week and apologized that his wife, Ms. Kennedy, could not make it.

"Both of us care very deeply about this plan, this land, and Martha's Vineyard," Mr. Schlossberg told the commission. "We've been working on this plan for a few years to get it as close to perfect to fit the needs of the environment and the needs of our family."

No one spoke against the plan, and there were no letters opposed to it. An abutter at the hearing called the plan an asset to the town, the Aquinnah planning board and conservation commission have both endorsed it, and Sheriff's Meadow Foundation and the Vineyard Conservation Society sent letters of support.

"We have the strong support from everyone we've been able to talk to," Mr. Renehan told the commission.

Commissioner Paul Strauss of Oak Bluffs asked whether the Wampanoag Tribe of Gay Head (Aquinnah) had commented on the plan. In the 1980s some tribal members and Mrs. Onassis engaged in a 10-year court battle over a 1.5-acre beach lot that was then jointly held. They eventually resolved the dispute with a land swap.

Mr. Renehan told the commission last week that he had heard nothing officially from the tribe, though he did meet with tribal members on the Aquinnah housing committee. The applicants have offered to make a $100,000 contribution toward a future project of the town housing committee.

The applicants have also offered to install state-of-the-art denitrification wastewater systems in any future buildings, and to donate up to $15,000 of the town's share to the Massachusetts Estuaries Project, which will provide better information about nitrogen sources in the Squibnocket Pond watershed.

Commissioners said the key issue before them is how to ensure that actual development - whenever it occurs - is sensitive to the habitat, scenic vistas and coastal resources.

Mr. Renehan and Vineyard land surveyor Douglas Hoehn, who helped develop the plan, argued that existing Aquinnah regulations are strict enough to ensure sensitivity. When any future buildings are eventually proposed for the property, they will likely require multiple special permits from a variety of town boards. The property falls in as many as four districts of critical planning concern (DCPCs), and as state-designated priority habitat will trigger extensive Natural Heritage review and permitting.

"The town of Aquinnah has the most comprehensive land use regulations of any town on the Vineyard," Mr. Hoehn told the commission. "The town is fully equipped to take care of any projects on these lots when the time comes."

Commission chairman Linda Sibley of West Tisbury noted that DCPCs are intended to give towns more land use control and allow the commission to let go of certain regulatory aspects, but she and other commissioners expressed concern that some of the more progressive Aquinnah regulations could at some point be challenged and possibly overturned in court.

Mr. Renehan responded that most Vineyard land use regulations have been upheld in court, and noted that he successfully argued the landmark three-acre zoning case for the town of Edgartown all the way to the state supreme court 10 years ago. "I would not be as bearish as you on the validity of the Aquinnah bylaws," Mr. Renehan told commissioners.

More than one commissioner said that while they harbor no doubts about the intentions of the current owners, the commission must think generations into the future and ensure permanent environmental protection. More than one commissioner suggested placing a threshold on development of the property that would trigger further commission review.

Mr. Renehan yesterday sent the commission a letter noting that the family would accept a limitation whereby if four houses are built on any lot other than the beach parcel or the 100-acre homestead, any further construction for that lot must go back before the commission.

Mr. Renehan at the public hearing last week pleaded with commissioners to go easy on the conditions.

"If I could tell you what to do, it would be in one word - restrain yourselves," he said. "Keep in mind this is a hell of a plan, but it only works effectively if we have lots to sell later. Please don't condition them too heavily."

Some commissioners suggested they were willing to support the plan as submitted.

"The applicants and their professionals have done an extraordinary job here of presenting a plan that addresses all of our normal concerns," said commissioner Carlene Gatting-Condon of Edgartown. "I applaud the applicants, and when the appropriate time comes I will look forward to making a motion to approve it with the conditions offered."

Other commissioners were also supportive, though less enthusiastic. Commissioner Douglas Sederholm pressed for conditions that would back up the current Aquinnah regulations.

"It doesn't hurt to have a belt and suspenders," Mr. Sederholm said. "If I knew the present owners were going to be here forever there wouldn't be any discussion because they have been fantastic stewards. But this is very special land, and we have to make sure it's protected forever."