The reforestation of the eastern United States is widely seen as one of the greatest environmental success stories of this nation. And nowhere has the positive change been more dramatic than in New England.

Over about 100 years, forest cover re-established itself on about nine million acres of land. New England is now the nation’s most forested region, with trees now covering some 33 million acres of a total land area of 42 million acres. The environmental writer Bill McKibben described it as “an explosion of green.”

And on Martha’s Vineyard that explosion was even more dramatic, as David Foster, director of the Harvard Forest, noted this week on one of his regular visits to Polly Hill Arboretum.

“A hundred and fifty years ago, this was an entirely agrarian landscape,” he said.

“Even in the 1950s, the great ecologist, Pete Ogden, said there were no forests on Martha’s Vineyard. There were scrubby woodlands, but they were all still coming back from the sheep era, when there were 15,000 to 20,000 sheep on the Vineyard.

“Today we’ve got lots of forests, and some quite large trees.”

Left to continue their recovery, he said, the Vineyard’s forests will only become more magnificent as they progress toward a mature state, 100 or 150 years from now. And more diverse. The oak and pine which now dominate will be joined by more beech, more hickory, more tupelo — which here we call Beetlebung — more maple and cedar.

Beyond the increased diversity and improved aesthetics — the falls of the future will grow ever more colorful here — there is perhaps an even bigger benefit. A regrowing forest stores huge amounts of carbon; those plants suck carbon dioxide out of the air and lock it up and mitigate global warming.

“There is now 33 million acres of forest, all of it young and growing very rapidly. New England is part of a huge eastern U.S. regrowing forest that is a big enough sink for carbon that it actually figures in global carbon budget,” he said.

That’s the good news. The not-so-good news is that the forests are once more under threat. This time, though, it’s not due to settlers who see the trees as an impediment to agriculture, as much as to population pressure. Particularly, ironically, from people seeking escape from the urban life for something closer to nature.

Those who care about the environment should not despair, however. There is a way forward, even allowing for a doubling of the amount of developed land, and also retaining at least 70 per cent of the New England region as forestland, trebling the amount under protection, and allowing for sustainable agriculture and timber production.

The 50-year plan is contained in a just-released report from Harvard Forest, Wildlands and Woodlands: a Vision for the New England Landscape, about which Mr. Foster will speak at the Agricultural Hall in West Tisbury next Tuesday.

“This is a report that addresses the conservation future of New England,” Mr. Foster said this week.

“It establishes some big, fairly bold goals for the conservation of natural areas, forestland as well as agricultural land. It looks at the way we shape our lives and develop our communities and advance economic well-being while also conserving nature, and increasing the agricultural products we get from our landscape,” he said.

“The Vineyard is a perfect place to talk about this in part because there’s a lot of interest in conservation, but also because the Vineyard has developed this fabulous Island Plan which in many ways does exactly what we’re talking about, very pro-actively and deliberately looking at the future of the landscape.

“The Vineyard is a unique place, but it’s also a bit of a microcosm of the issues we face across New England. It’s way out ahead of the curve in terms of the pressure of development, fragmentation of the natural landscape, what we call in the book the perforation of landscapes,” he said.

By perforation, he means “the plonking down of individual large houses in the middle of fields, forests, sandplain grasslands and so on.”

And it’s a relatively new phenomenon.

“There’s been this historic flip,” he said.

“The Island Plan identifies 1970 as the point of change. The former editor of the Gazette, Henry Beetle Hough, in his writings, identified 1950. But some time between 1950 and 1970, there was this change and people decided the countryside was the place to live. Up-Island became more attractive. Out in the middle of the woods or the open fields became more attractive.”

Surely, though, the placing of a house on an acre or three or five of otherwise wooded land on Martha’s Vineyard was not such a big environmental problem, particularly when compared with the alternative of densely-settled areas, where the woods were largely removed?

Well, he said, actually it is.

“There’s the direct footprint of your house and yard, but beyond that is all the extended impact of you and your children and your cat, dog, mountain bikes and everything else you have out in the woods around that.

“It depends on exactly what ecological process you’re talking about, but there can be significant effects.

“Think about it in terms of carbon. You plonk your house down, that releases a lot of carbon, and forever keeps that area from taking up any more carbon. Then wildlife habitat, you’ve obviously disrupted that.”

Then there is the energy cost of getting to and from that house. The roads and other infrastructure which it requires.

“For lots of reasons, from energy efficiency, transportation, for social connections, concentrations of people into the historic centers of commerce and residence makes an awful lot of sense.

“It’s much better to keep these areas intact, to keep them continuous and connected and think of ways to live around the margins,” he said.

However, he said, It’s not like the plan is one of simple preservation.

“Our report in general, and my philosophy, is very much one of increasing local dependency on local resources. We argue New England should not just protect its forests but protect them and use them,” he said.

“That’s why I think the increase of agriculture here on the Island is a good thing. If there’s any place that’s needed, it’s here.

“And it’s not about making the Island self-sufficient. It never has been self-sufficient. The important point is to re-orient people so they appreciate where food comes, where wood and energy come from. To connect people more with the need for conservation, by helping them understand the sources of their resources . . . .

“The way we pitch it in this report is essentially optimistic, that history has given us a second chance.

“When the first time European colonists confronted the forests of New England, they cut them all down, took the resource and converted much of the land to agriculture. We’re very fortunate that when they abandoned agriculture, it came back, essentially without anyone doing anything.

“We’re now at a peak; we’re never going to have more forests than we do now. So we have a second chance. We can learn from the past and apply it to the future.”

Vineyarders are invited to bring their questions and concerns to the Agricultural Hall on Tuesday night, at 7:30, where copies of the report will also be available. The cost is $10, or $5 for Polly Hill Arboretum members.