AYER — On an old pig farm in the dwindling woods northwest of Boston, teams of excavators and construction workers are clearing thousands of trees, rerouting the flow of rainwater, and carving up hills into newly paved roads. With the housing market booming in this town of 7,500 residents, the final construction stage is underway for 168 vinyl-sided homes, most perched atop a denuded, acre-size plot.
The new subdivision called Pingry Hill is part of a surge of building in Ayer, which has seen more development per square mile than any other municipality in Massachusetts. All that construction, here and elsewhere in the state, has contributed to the loss of nearly 50,000 acres of forest — at a pace of 13 acres a day — between 2005 and 2013, according to a major survey of the state’s land conducted by the conservation organization Mass Audubon.
The steady spread of housing, roads, and other development has left 22 percent of the Commonwealth’s land covered by asphalt, concrete, or other impermeable materials — up from 14 percent in 1981 — hampering wildlife habitats and exacerbating the challenges of climate change, according to the Mass Audubon report.
The loss of the state’s natural land, however, has slowed from a decade ago, when Massachusetts was losing 40 acres of open space a day to development. It has also coincided with an increase in the amount of protected land, with federal, state, and local authorities, as well as nonprofit groups and private landowners, prohibiting development on more than a quarter of state land, up from 10 percent in 1987, according to the report.
While more than three times the amount of land was protected than was developed between 2005 and 2013, the report raised concerns about signs of a resurgence in development, especially now that the economy has rebounded.
“We can’t be complacent; development is coming back,” said Jeffrey Collins, director of ecological management at Mass Audubon and an author of the report, citing recent housing permit data that indicates building has returned to prerecession levels. “The slowed pace of development reflected the slowdown in the economy.”
The main concern, he said, is that too much of the state’s forests, wetlands, and other “critical landscapes” remain threatened by development. That land is either considered critical for conserving the state’s biodiversity or vital to absorbing the increased precipitation and flooding expected as climate change makes the region warmer and wetter.
With a little more than half of Massachusetts still undeveloped, Collins and others called on the state to ban development on an additional 1.5 million acres — more than half of the remaining undeveloped land — that is considered vital for conservation.
“If and when that 1.5 million acres is acquired . . . there will be a tremendous amount of work to do to restore wetlands, rivers, watersheds, forests, and other lands to not only rid them of invasive plant species and restore water connectivity, but to bring them to a point that takes maximum advantage of their natural resiliency in the face of long-term climate change,” said Jack Clarke, director of public policy and government relations at Mass Audubon.
The report used satellite images and analysis from Boston University researchers to map the landscape. It identified the towns experiencing the highest rates of development as those within 10 miles of Interstate 495 and those in the southern Connecticut River Valley.
“It is notable that many of these communities include or are near the ends of the MBTA commuter rail system,” the authors wrote in the report.
The vast majority of development between 2005 and 2013 cleared forests to make space for low-density residential housing developments. Most of the wooded areas were lost in Southeastern Massachusetts, Cape Cod, and south of the Quabbin Reservoir.
Plymouth, the state’s largest town, had more development than any other community, with 779 acres of land converted to residential or industrial uses in that period, including 419 acres of forests. Nearby Carver, Wareham, Middleborough, and Taunton also saw large swaths of forests and pastureland converted to housing and commercial uses.
While farmland may have increased modestly in recent years to more than 500,000 acres, the state lost thousands of acres of open land to development, including croplands, beaches, recreational fields, and other land with little vegetation. Lynnfield, for example, saw more than 21 percent of its open land converted to housing and commercial development, a higher proportion than any other community, with Chelsea losing more than 17 percent and Burlington 15 percent of their open land.
In Ayer, which had nearly 150 acres of its 9.5 square miles developed between 2005 and 2013, the rapid changes have sparked tension.
In a town that still lacks traffic lights, local officials are proud of the growth, especially since the Army closed nearby Fort Devens in 1996. They see well-appointed housing on what had long been barren land, improvements at an expanding high school, perks from new restaurants to a thriving industrial park in town, which is 35 miles from Boston and less than an hour ride on the commuter rail.
They note the number of single-family houses and condos, as well as their total taxable valuation, has risen by about a quarter over the past decade, allowing the town to increase its budget by more than 20 percent. That’s enough this year to hire a new town engineer, buy a new heavy-rescue firetruck and a new vehicle for the police chief, and replace the windows at the 138-year-old Town Hall.
“We’re an up-and-coming town,” said Jannice Livingston, vice chairwoman of the town’s Board of Selectmen. “We’re absorbing everything quite well.”
But some are uneasy with the development, noting that residents at Town Meeting in May voted to eliminate funding for the Planning Board and Zoning Board of Appeals.
Carolyn McCreary, a former selectwoman and local activist, led the effort to block the funding, asserting that neither board has served the community well. She has urged town officials to update zoning bylaws to encourage more environmentally friendly development and said residents would be better served by volunteers than the current staff.
On a recent morning in the cleared woodlands of Pingry Hill, McCreary called the new subdivision an example of “excessive development” that reflected the town’s “lack of leadership and lack of vision.”
“There’s been no work here to preserve open space,” she said.
She pointed at the broad lawns and winding roads where mature trees covered the area only a few years ago. “It shouldn’t have to be this way,” she said. “We have to learn to do things better.”
Rick Roper, co-owner of Pingry Hill, has built more than 200 homes in Ayer over the past 20 years and said the only significant impediment since the recession has been a lack of inspectors to keep up with the quick pace of building.
As he steered his sport utility vehicle around his property, where earthmovers were grading mounds of dirt and excavators clearing trees, Roper said he has spent about $15 million building new roads and has replaced wetlands with over 100 retention ponds, which capture the diverted water.
He already has built more than half the homes he has planned, all of which require the removal of roots to connect a maze of underground water, sewer, gas, and electric lines. With eager buyers since the economy recovered, Roper wasn’t surprised to hear that Ayer had more development per square mile than anywhere else in the state.
“We’re responsible for that,” he said.
With rising prices, Roper said he expects more to come.
“It’s a good time to build. We’re finally making money.”