Nature's Little Weed Eaters

Why Use Sheep As Weed-eaters?

Problem: How do you keep 25,000 acres of land underneath power lines in New Hampshire free of trees…trees that can grow tall enough to hit those lines and cause power outages?

It's not a small problem. When a tree finally stretched its limbs skyward sufficiently to hit a power transmission line in the northwest a few years back, it caused a power outage in four states.

In the past, power companies have mowed trees down, sprayed them with chemicals and cut them back by hand in a frustrating, time consuming -at times dangerous- not-to-mention expensive effort to keep mother nature from doing one of the things she does best, especially in New Hampshire: grow maple, poplar, cherry and pine trees in great numbers.

Enter the lowly sheep. Think of them as Mother Nature's own lawn mowers -or, more specifically- tree mowers.

"Maple, poplar cherry and pine trees are cake and ice cream to a sheep," says Dick Henry, former shepherd, now President of Bellwether Solutions, a company that devises natural methods to solve troubling environmental problems. It was Dick Henry who approached PSNH with what, at the time, seemed like a curious notion - namely, letting flocks of sheep, a few sheep dogs and some shepherds work to keep the power lines free of trees.

That was back in 1998. Today, no one is viewing the notion that sheep can keep power lines tree-free as a foolhardy idea.

"I started looking at other ways I might be able to make money using sheep, " Henry said. "I'd heard of a program in Europe where they used sheep to keep deciduous trees and herbaceous vegetation in check in conifer stands. I thought 'Gee, if sheep can keep maple, birch and cherry trees from growing in conifer stands, they can probably keep them from growing under transmission lines'." Turns out he was right. Learn more about the kinds of sheep used. Each year, about one-fifth of PSNH's 1800 miles of power grid rights-of-way are cleared at a cost of about $2.5 million. While PSNH mainly employs mechanical mowers and hand cutting to get most of the job done, the Grazing Power Project tested the use of more than 1,000 sheep in sections of our transmission rights-of-way.
"A sheep won't step on a turtle, or kill frogs and other wildlife," Henry said. "And beneficial insects have time to fly out of the way and then return later," he explained.

Perhaps most beneficial-and under close study from the University of New Hampshire-- is the sheep's ability to not only remove the leaves and stems from a tree, but when the sheep are allowed to return in 40 days for a second feeding, the trees in many cases actually die, never to return. "A mower cuts the trees off at the ground, but there's lots of energy left in the roots," Henry explained. "By removing the leaves and stems, and then doing it a second time in 40 to 50 days, the sheep rob the trees of the energy the roots need to send out shoots."

And sheep aren't particularly dainty about the way they eat either. A fully-grown ewe will stand on its hind legs and remove well over 90% of the leaves on a tree up to five feet high!

During New Hampshire's growing season, the sheep chowed down on seedlings and saplings at a rate of up to three acres a day under power lines in the towns of Northwood, Barrington, Lee, Rochester and Strafford.