The Sheriff’s Meadow Foundation this week issued a public apology and launched an overhaul of its land management practices following the revelation that large numbers of trees and other plants had been dug up from two of its preserves and used to landscape an exclusive private property on the North Shore.

In a statement issued on Wednesday this week, the foundation acknowledged a “failure to initiate internal discussion, follow regulatory notification procedures, understand the scope of the activity contemplated and provide adequate supervision of any removal efforts [which] point out weaknesses in our procedures and, in this case an unfortunate lack of judgment.

“We apologize to our supporters, to those who have entrusted their properties to us, and all the conservation-minded citizens of Martha’s Vineyard.”

The land trust, which was founded in 1958 by the late editor of the Gazette, also has terminated its previous handshake agreements with local landscapers, which have allowed them to take small numbers of plants from foundation land in exchange for help in maintaining that land.

In the future any such activity will be subject to formal, written agreements, foundation board members said.

The two foundation properties, the Caroline Tuthill Preserve in Edgartown and the Priscilla Hancock Meadow in Chilmark, were left damaged by heavy earth moving equipment brought in by contractors hired to landscape the 30-acre property of Dirk Ziff near Lambert’s Cove in West Tisbury.

An inspection last week by Tim Simmons, a restoration ecologist with Natural Heritage and Endangered Species program of the Massachusetts Division of Fisheries and Wildlife, found several breaches of the Endangered Species Act by both the foundation and Mr. Ziff.

The two Sheriff’s Meadow properties, as well as Mr. Ziff’s, are listed as priority habitat, a state designation applied to places which harbor rare or endangered animal and plant species. Any alteration of priority habitat areas is subject to review by the Natural Heritage and Endangered Species Program (NHESP).

But Sheriff’s Meadow did not inform Natural Heritage.

Nor did the contractors working for Mr. Ziff — John Hoff and Oakleaf Landscape, who had a handshake deal with Sheriff’s Meadow — and David Rathbun of Bird Island Trust — which brought in the heavy equipment.

Material also was taken from a third piece of land at Iron Hill farm in Oak Bluffs by another contractor, Adrian Higgins, of Vineyard Engineering.

Last week Mr. Simmons said he had yet to determine whether that land was priority habitat.

A subsequent check showed it was not, and yesterday Mr. Higgins said he had checked before lifting the little bluestem meadow to ensure he was not violating the law.

Mr. Simmons has asked Sheriff’s Meadow to submit a report detailing the species composition and extent of the affected area. The Ziff contractors will be required to supply similar information, after which Natural Heritage will determine a regime of restoration standards.

In an interview with the Gazette this week, spokesmen for Sheriff’s Meadow — the new executive director Adam Moore (who came to the job only at the start of May), board president Steve Crampton and vice president Emily Bramhall said they looked forward to working with natural heritage to restore the land and also to making the changes that would restore trust in their stewardship of the land.

“We are obviously concerned because what this has done is gone to one of the pillars of our success, which is our trust and integrity that we’ve built over the years,” said Mr. Crampton.

But while they did not want to duck responsibility for their failings, the foundation leaders also made it clear they felt the informal relationship of trust on which their previous management arrangements with landscapers was based had been betrayed.

“The organization commenced a handshake agreement with this landscape company to remove trees and shrubs that we desired removed, in one case to restore a meadow at the Caroline Tuthill preserve and in the other case to remove encroaching woody vegetation so that sandplain grasslands can be restored at Priscilla Hancock,” said Mr. Moore.

But the size and numbers of plants taken and the degree of disturbance to the properties was beyond what was anticipated.

“I don’t know precisely when [the work] started, but it was sometime in the spring. We did not exercise adequate oversight. There was no written agreement,” Mr. Moore said, adding:

“What I did was put a halt to all such arrangements we have wherever we may have them and drafted a policy that our property management committee reviewed today [Wednesday]. We’re revising it. We need a policy that calls for written agreements . . . even if there’s not funds being transferred, it needs to be in writing.

“If we have an agreement for something to occur of a certain size and it’s in writing, it will be much easier to keep it to that size.” He continued:

“Maybe we’ll have a barter arrangement with an outside firm in the future, but it will be subject to a policy the board has approved in accordance with what is deemed to be best ecological practice and consistent with our management plan and having a written agreement in place.”

He said the foundation did not submit a management plan for the work at Caroline Tuthill to Natural Heritage, and while it had submitted one flagging its plans for the restoration of sandplain grasslands at Priscilla Hancock, that plan had not mentioned transplanting plants.

He has now sought a formal presentation to Sheriff’s Meadow staff on the rules of the state program and has begun the process of reviewing plans for all the foundation’s other holdings.

“So many of our properties are in what they call priority habitat,” Mr. Moore said. “We should start with an ecological inventory of the plants and the wildlife, and then with some goals in mind, write a plan.”

Ms. Bramhall said informal arrangements with landscapers had worked well for decades.

“Just as a for-instance, with John Hoff we’ve had other agreements where he’s taken certain trees and shrubs, and when we needed to have a stone retaining wall rebuilt he did it for us. When we had a tractor donated to us . . . he came with his trailer and truck and transported it from the boat to Edgartown,” she said, adding:

“The bartering has worked for us.”

But she acknowledged recent events had raised big questions about whether Sheriff’s Meadow always got fair value in such trades.

“That’s something we do need to sort out — the real value of these trees. And that will take some work to research,” she said.

They had no idea of the amount of money Mr. Hoff had made. Other landscapers privately estimate it in the hundreds of thousands of dollars.

Said Mr. Crampton: “What a landscaper does in selling it for retail or whatever, we never considered before.

“The process has become warped . . . because someone with endless pockets has injected themselves into it. The system went out of whack and we were taken advantage of, intentionally or otherwise. So now we have to put in force procedures to ensure it won’t happen again.”

That sentiment was one commonly expressed. Russell Walton, the Chilmark conservation agent, whose father donated the land for Hancock preserve to Sheriff’s Meadow, said he had never had any previous concerns about the barter system employed to help maintain it.

“But it seems this got a bit out of hand,” he said,

“For a couple of weeks they had trucks with trailers behind, running in and out. And they had a Bobcat loading the trucks very busily, pretty much all day for several days.”

His principal concern was that the work proceeded into the start of the bird nesting season.

“This area is intended to be a wildlife refuge and they were working into the beginning of the nesting season and there were things like harriers and maybe even short-eared owls, which are definitely of special concern. And any possible disturbance to those critters is not desirable,” Mr. Walton said.

Michael Donaroma, a prominent landscaper who had a long informal agreement to help manage Caroline Tuthill, said he could not understand how the foundation failed to see the enormity of the work done this time.

“They always watched me like a hawk,” he said. “[Former executive director] Dick Johnson would be there watching every trowel full of sand I moved.”

Like many others, Mr. Donaroma blamed the influence of the vast amounts of money Mr. Ziff had to offer. Through the week a number of people reported having been made large offers for their plants or meadows.

Others pointed to an incident reported in The New York Times in 2002, involving Mr. Ziff’s father, in which material — in this case boulders — were taken from a public nature preserve for landscaping around a mansion in Pawling, N.Y.

After the district attorney launched an investigation, the Ziff family paid $9.25 million to the county but admitted no wrongdoing.

But Sheriff’s Meadow leaders said this week they have received no money for the current work. They said Mr. Ziff had been a previous donor.

Contacted yesterday by telephone, Mr. Ziff declined comment.