Jun 152014

Tom Wessels leading a walk through Gamlin Springs with members and friends of the Groton Conservation TrustSusan Hughes

Tom Wessels leading a walk through Gamlin Springs with members and friends of the Groton Conservation Trust

“The central New England transitional forest is diverse as it has over 140 woody species from both the northern boreal white and black spruce forests, and the temperate oak forests to the south, but it’s cultural history is one of sheep fever,” ecologist, professor, and author Tom Wessels told members and friends of the Groton Conservation Trust.

He explained how the woods can hide artifacts left from New England’s first large-scale market farming in a talk Saturday at the Groton School as part of the GCT’s 50th year anniversary celebration.

In 1810, Vermonter William Jarvis was able to smuggle 4,000 Merino sheep out of Spain during the fog of the Napoleonic War. These prized and embargoed animals had been developed for their prolific, fine, non-itchy wool. Two years later, during the War of 1812, tariffs were imposed on all imported British wool. Then the gradual development of power looms in New England’s new mill towns gave further incentive to New England farmers to begin clearing their forests so they could graze sheep. By the 1840s nearly 80% of the land had been deforested, Wessels said.

Wool import tariffs swung wildly and eventually, the price of wool dropped. The overgrazing of 5 million sheep had so eroded New England soils that in the 1840s half the people living in western Massachusetts and Vermont left for the more fertile land of Ohio.

Signs of that boom and bust agriculture can still be found in Groton’s and New England’s woods.

“The 125,000 miles of stone walls in New England were built in about 30 years,” Wessels stated. “There was no longer enough wood for fencing, and overgrazing had exposed the stones.”

The early Fence Warden was a powerful town position during sheep fever times. These officials walked the stone boundary lines and could level fines if walls did not meet a minimum height. They could also bring a transgressor to account for his lack of diligence before a Sunday congregation.

“Grazing sheep could devastate a grain field, so to keep the peace it was important to maintain the stone walls,” he said.

The forests of New England did return. The overgrazed pastures rebounded first with very low-growing nonnative basal rosette weeds that sheep could not get their teeth around. These were followed by nonnative coarse weeds, like thistles, then exotic berry-producing thorny shrubs, like the Multiflora Rose. Trees sprouted in these shrubs, beyond the mouth of grazers.

“If it is a diverse canopy, the area was overgrazed for a long time. One species stands are usually indicative of old hay fields, which were not grazed and also do not have the exposed stones.”

Wessels drew from a book he co-authored, Reading the Forested Landscape: A Natural History of New England, when he talked about the weird apple trees he discovered early in his career. He found some of these bonsai trees to be over a hundred years old, left tiny by the constant grazing of sheep, but surviving. Most of these apple trees are now gone. Another iconic sign of the early pastures, large horizontal low-limbed pasture trees, will soon follow.

Following the talk, Wessels led a group through the Trust’s Gamlin Crystal Spring Conservation Area.

GCT spokeswoman Susan Hughes wrote in an email, “We took the pond loop on the Gamlin Crystal Springs property. Tom told stories about the varieties of trees found in the woods and challenged us to use our investigative thinking to tell their story. For example, ‘Why does the paper birch shed its bark so easily?’ To help shed lichens so the bark stays white to deflect the sun. ”

“He also helped us identify the previous use of the land. As he said in the talk, about 75% of all NE land was once pasture land. He was looking for a tree that could be dated back to the mid-1800’s to identify original forest land, not used for pasture. It was midway through the walk when we located the remnants of a stone wall, indicating pasture, and then just beyond was a huge, divided oak, with which he could date the right time! So the back half of the property had always been forest land, something we didn’t know about our property.

“Despite the demise of so many beautiful old-growth trees like the American Chestnut and the Elm, he did leave us on a positive note. He said these trees will make their comeback as they are developing resistant varieties now. And that we will be able to manage the many invasive species (not rid ourselves of them) but manage them in a way that our native species can thrive.”

Wessel’s talk was underwritten in part by a grant from the Groton Commissioners of Trusts Fund.