On most Thursday mornings along the Mount Vernon segment of the George Washington Memorial Parkway, or GMWP, local “weed warriors” whack and pull invasive or non-native plants. They are trying to control plants like English ivy, bamboo, bush honeysuckle and garlic mustard.

The National Park Service estimates that many parks and nature preserves in Virginia typically have between 25 and 34 percent non-native plants. Non-native plants can be called “invasives,” “aliens,” “exotics” or “non-indigenous plants.” Generally, they are plants introduced both intentionally and accidentally into an area far from their native habitat, and they often cause ecological and economic harm. 

Invasive plants have few controls or lack natural controls such an insects and disease to keep them in balance. Many invasives can out-compete native plants, form a monoculture, reduce biodiversity and destroy native habitats. Unlike invasives, native plants evolve over thousands of years with other species and provide habitat and food for wildlife species with which they have co-evolved. Much of Northern Virginia’s native biodiversity has been lost to non-native trees, plants and monocultures like grassy lawns. 

The Mount Vernon-area weed warriors are volunteers from the Friends of Dyke Marsh, or FODM, headed by FODM Vice President Ned Stone, and the Environment and Recreation Committee of the Mount Vernon Council of Citizen Associations, headed by Chairwoman Betsy Martin. Christina deMariano of the National Park Service coordinates their work.

Volunteers are working in three areas: near the west-side turnout just south of Morningside Lane; next to the parking lot across from Waynewood Boulevard and the parkway; and the pedestrian entrance to Dyke Marsh, just south of Marina Road.

Stone has been whacking weekly for four years. “We would like Dyke Marsh’s native plants to be able to thrive, and the invaders are choking them out,” he explained as his reason for toiling every week in every season.

“Our biggest accomplishment so far has been clearing about a one-third of an acre of bamboo over the past nine months,” Martin said. “We also did a good amount of clearing of bush honeysuckle and other invasives on both sides of the trail north of Pipeline Bay. We did a lot of cutting of ivy and oriental bittersweet off the trees at the Waynewood parking area, and you can see dead ivy on the trees,” she said.

Six common invasive plants found in Fairfax County are English ivy, tree-of-heaven, oriental bittersweet, purple loosestrife, Japanese stilt grass and Japanese honeysuckle. Of 2,500 species of vascular plants that grow in the wild in Virginia, around 350 are not native, according to the Virginia Department of Conservation and Recreation. Invasive species (plants, animal and pathogens) cost the state approximately $1 billion a year, according to the department.

The National Park Service actively manages about 30 invasive plant species on the parkway, with efforts focused on bush or amur honeysuckle, porcelainberry, Japanese honeysuckle, English ivy and kudzu. The 7,374-acre packway is a national park, and NPS has three staffers who are the natural resources management staff. 

“Controlling invasive plants is like a marriage. It’s a long-term commitment,” NPS’s Erik Oberg told 80 locals at a March 24 workshop. Oberg is the natural resource management specialist for the parkway.

At the gathering, Cliff Fairweather explained how people can make their properties more wildlife friendly. Describing grassy lawns as “ecological deserts,” he recommended people use native plants, remove invasives, reduce pesticides and fertilizers and conserve water. Fairweather was then with the Audubon Society of Northern Virginia. He is now with Arlington’s Long Branch Nature Center. For information, visit http://www.audubonva.org/index.php/audubon-at-home.

“Prevention is the first line of defense against invasive species,” according to the website of the National Invasive Species Council.

To volunteer to be a weed whacker, contact Christina DeMariano at Christina_Demariano@nps.gov or call 703-289-2545. NPS offers training in species identification and removal techniques.