Powerlines as Habitat

In forested areas where hardwood regeneration is desired, foresters frown on dense shrub-and-fern understories. But under powerlines, native berries and ferns are the goal.

Significant powerline projects are in the works throughout northern New England and New York, as the grid is updated to accommodate more power from Quebec. In the pages of the local papers, residents weigh the costs and benefits, with proponents touting benign progress and opponents seeing a scar on the landscape they love. The Northern Pass proposal in New Hampshire has generated particularly strong opposition. But how does nature see things? From an ecological perspective, is a powerline good or bad? The answer, of course, is “it depends.” In some cases, powerlines become an eroded swath and a monoculture of invasive plants. But in other cases, the local environment benefits from the diversity of habitat the powerline provides, and certain plants and animals come to thrive beneath the wires.

Recently, both National Grid, a company that owns and operates 8,600 miles of electric transmission lines in New York, Massachusetts, Rhode Island, New Hampshire, and Vermont, and the Vermont Electric Power Company, or VELCO, which maintains 660 miles of transmission lines in Vermont, expanded their powerlines without too much drama in New York and Vermont. How did they do it? First, they routed new lines through an existing powerline corridor. This had less impact on both the environment and local residents. But the companies also credit their commitment to managing their rights of way to benefit both the bottom line and the environment.

On a recent midsummer day, I went to the VELCO powerline in Pittsford, Vermont, for a first-hand look at the company’s management techniques. The powerlines were impossible to miss – the high-voltage wires, supported by 80-foot-tall poles, buzzed as they carried electricity along the hillside through a corridor 250 feet wide. But on the ground, a threatened species of sunflower known as harsh sunflower (Helianthus strumosus) was surrounded by milkweed, daisies, thimbleberries, daisy fleabane, wood lilies, and even a Canada lily. Tiger swallowtails zoomed over the flowers. Three tom turkeys, two deer, and a red-tailed hawk were roused by our presence and sought shelter in nearby trees.

That a threatened species found refuge in a powerline right of way is not unique to this site. In New Hampshire, one right of way is managed by Public Service New Hampshire (PSNH) to maintain habitat for the New England cottontail, which is an endangered species in New Hampshire and a candidate for federal listing. Shrubland bird species that are otherwise rapidly declining in the Northeast, such as the eastern towhee, find welcome homes along powerline corridors. In Massachusetts, a bee that was thought to be extinct was rediscovered along a powerline. There are rumors that rare wild lupine, and the federally endangered Karner blue butterflies that depend on it, can be found in powerline corridors near Albany, New York, and Concord, New Hampshire. New Hampshire powerlines are also home to the state-endangered frosted elfin butterflies.

Common species benefit, too. Deer, bear, turkey, and ruffed grouse, to name just a few, love powerline rights-of-way and thrive in the edge habitat they create. Spend two minutes under a powerline, and you will find that, like any forest landscape, a powerline corridor can be managed well or poorly. The devil, as they say, is in the details.

When trees get out of line

Powerlines and tall trees don’t mix, but how can tall trees be kept at bay indefinitely? A collection of methods known as integrated vegetation management, or IVM, is the standard the power industry uses to manage transmission rights-of-way.

“Integrated vegetation management provides long-term management of powerline rights-of-way,” says Teri Niedzielski, lead forester for transmission forestry strategy for National Grid. She works out of its Utica, New York, office. “It’s not simple eradication but rather several techniques combined to protect the lines from vegetation. The primary methods are herbicide application, hand-cutting, and mowing.”

Christopher Nowak agrees. An associate professor who leads the State University of New York’s College of Environmental Science and Forestry’s integrated vegetation management program, Nowak teaches a six-step IVM process. He notes that there is an official definition of IVM from the American National Standards Institute (ANSI A300, Section 7), the same organization that approves standards for everything from paper sizes to the arrangement of wires in computer connectors.

“Integrated vegetation management is not just this treatment versus that treatment,” says Nowak. “It’s the full suite of concepts, from understanding the ecosystem dynamics to listening to stakeholders.”

On the surface, sustainability means creating an ecosystem where tall trees won’t grow. When tall trees don’t grow, they don’t have to be cut down. Mowers don’t have to be sent in every four years to tear everything down, dripping oil, belching exhaust, and risking erosion and the introduction of invasive species.

Dig a little deeper and you’ll find that power companies are not just managing existing ecosystems, they’re attempting to create new ones. The goal is not early-successional habitat – a few passes with a forestry mower would leave a lawn of multi-stemmed hardwood stumps that must then be perpetually managed. Rather, the goal is to create permanent shrubland habitat, where small woodland grasses, ferns, herbaceous plants, and shrubs like blueberries and blackberries become permanent fixtures.

Shrubland habitat is not the only ecosystem that may be created. Vermont state botanist Bob Popp reports that a prairie-like grassland ecosystem has grown in a powerline right-of-way near Vernon, Vermont. In parts of New York and New Hampshire, a fire-dependent sandplain ecosystem, also known as a pine barren or a pine bush, once prevailed. Without firescouring away the hardwood trees, those areas have reverted to forest, but when trees are removed along powerlines, the sandplain ecosystem returns.

Typically, herbicides are used to promote these ecosystems, and that’s one of the reasons powerlines can be controversial.

“If we use just a manual control method, like a chain saw, the trees are going to resprout,” explains Jeff Disorda, supervisor of right-of-way management at VELCO. A selective herbicide application will kill the tree’s root system, he says. “It allows the compatible species to fill back in – the grasses, forbs, and ferns. Hardwood trees will have a harder time seeding into an established understory.”

For those imagining herbicide sprayed over rights-of-way from an airplane, National Grid’s Niedzielski says, “Nobody has done that in decades.”

These days, herbicide is applied by hand, either to a stump or leaves, from a backpack sprayer. Power companies tend to favor foliar applications because they can be done quickly. Stump applications may require two crews, one with expertise in chain saws, the other with expertise and a license for herbicide application. Stump applications are considered more precise and are favored by wildlife managers in sensitive areas, such as near endangered plants. With either technique, the goal is to use less and less herbicide each year, until the system sustains itself.

In a new right-of-way, a conservation seed mix might be spread to stabilize the soil against erosion, but the power companies using IVM tend to have strong faith in the dormant seed stock doing its thing.

“In most cases, Mother Nature has pretty good ways of getting species to grow in the right-of-way,” says Disorda. He’s found that plants like ferns, goldenrod, and blackberries grow without encouragement. The power companies mostly discourage unwanted plants, mostly tall trees, but also invasives such as phragmites and Eurasian honeysuckle.

“We look at the right-of-way as a whole system, but there are aspects that we treat differently than others,” says Niedzielski. “In the wire zone [directly below the wires] we’ve found that a combination of vegetation is the best community – that includes grasses, ferns, and shrubs. On the edges, we have a transition zone to the mature trees on the edge of the forest.”

Trees that are less than 12 feet tall at maturity, such as dogwoods, apple, and some willows, are typically allowed to grow in the right-of-way because they won’t interfere with the wires.

Not all power companies use herbicides and not all companies that use herbicides use them everywhere. In general, herbicides aren’t used in or near wetlands. They aren’t used near reservoirs or private water supplies, such as wells. “In Vermont, every landowner has the right to have us use an alternative to herbicides, if they choose,” says Disorda.

Sometimes, Nowak suspects, power companies favor tree mowing over herbicide application because they have invested in a fleet of forestry mowers and the personnel to run them; sometimes, it’s in deference to local property owners. Fresh from his own encounter with a citizen irate over his use of herbicides, he notes that sometimes power companies feel it isn’t worth the trouble of trying to change public opinion.

“Generally speaking, our society is sensitive to the use of herbicides, and it should be,” says Fuller. “My own opinion is that the environmental and resource community needs to help people understand that in many cases, the careful use of chemicals results in the lightest environmental impact.”

The dark side of keeping the lights on

While a well-managed powerline corridor can be an ecological boon, a poorly managed right-of-way can be an environmental disaster. In areas full of invasive plant seeds, removing a forest overstory and introducing sunlight can be a recipe for trouble. Stripping away trees with heavy machinery can leave naked soils vulnerable to erosion. And if herbicides are used sloppily, they can pollute water sources and kill valuable plants.

Fortunately, most of these problems can be avoided. Responsible power companies prevent erosion in the same ways responsible loggers do. They sow quick-growing seed in vulnerable areas to hold down the soil. They stake hay bales above water sources so soil and silt don’t run into streams. VELCO even specifies that the hay used for erosion control must be from fields certified as free from invasive plants, or come from a seed-free second cutting.

“With invasives, our focus is on new populations,” says Brian Connaughton, VELCO’s environmental team leader. “If there is an invasive species that extends off the corridor, or is on both sides of the corridor, there is not much we can do.” If a new population of invasive species appears in the corridor, however, it is treated with herbicide. Disorda adds that if a landowner is trying to manage invasives on land adjacent to the corridor, VELCO will manage them on the corridor as well.

Managing for wildlife can be more complicated. While certain animals prefer shrubland ecosystems, including about 40 shrubland bird species, others do not.

Birds such as the scarlet tanager, wood thrush, and blackthroated blue warbler benefit from living in large forested tracts. Some smaller animal species are hesitant to cross open areas, so corridors can isolate small populations from the genetic diversity they need to thrive. Flying squirrels, for example, prefer to travel when the next tree is within soaring distance. Salamanders risk dehydration when they travel across areas without cover. And, says Nowak, “certain beetles won’t cross a path larger than three feet in width.”

Nowak says that powerlines make it easier for songbird predators like blue jays, crows, skunks, and feral cats to reach their prey. The brown-headed cowbird, a parasite that lays its eggs in other birds’ nests, flourishes at forest edges. Nowak says that rights-of-way with vegetation of varied height can thwart the cowbirds.

Keeping power companies in line

Because improperly managed powerlines can be a detriment to the local ecosystem, it’s in the public’s best interest to see that they’re managed well. Many states regulate power companies to ensure they manage powerline corridors proactively. For example, Nowak says that New York State regulations practically guarantee that power companies use the same six-step IVM process that he teaches his students. He says that Massachusetts also has effective right-of-way management regulations.

But, he points out, strict regulations don’t always work out well for the environment. The 2003 Northeast blackout led to new federal regulations that wielded penalties of up to $1 million for vegetation-caused power outages on the highest voltage transmission lines. “In response, people started to mow and widen their legally prescribed width,” he observes. “It was like going back 50 years.”

A strong corporate commitment to sustainability can achieve the same results as the best regulations, he notes, pointing to a power company in New Mexico that he believes is doing good work, in spite of a lack of state regulations.

As environmentalism continues to evolve and become more proactive and less reactive, conservation organizations and state government have begun to partner with power companies to steer their management work. Several Vermont power companies, including VELCO, work with the National Wild Turkey Federation, which supplies a turkey-friendly, anti-erosion seed mix to VELCO and technical assistance to other energy companies around the country. In New Hampshire, power companies and the Fish and Game Department are working on New England cottontail restoration projects.

Back on the powerline in Pittsford, the rare harsh sunflower is a good example of the increased responsibilities power companies have when it comes to ecological management. In 2006, VELCO needed to expand this powerline corridor from 150 to 250 feet to accommodate a new 345-kilovolt transmission line. The threatened sunflowers that their powerlines helped cultivate were now within a construction zone and had to be protected. Connaughton said that foresters took extra care to make sure that, in spite of the heavy equipment all around them, the plants would not be trampled, run over, or poisoned with herbicides.

The sunflowers were well-marked and herbicide was sprayed on stumps, not on leaves. Those few sunflowers not only survived the clearing and construction but flourished, gradually filling an area eight feet in diameter with too many individual plants to count. And what about where the trees were cleared to expand the right-of-way? Another, even larger patch of harsh sunflower is thriving, with powerlines soaring overhead.

Madeline Bodin is a freelance writer who lives close enough to a recent transmission line expansion project in southern Vermont that she could hear the buzz of chainsaws.

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