Invasive species don’t just choke up local ponds and drive out natives; they cost the United States up to $200 billion a year. While non-native animals such as Asian shore crabs and pike have gotten a lot of attention, invasive plants also are a growing problem.
If you are out driving on a country road, watch out for any Japanese knotweed, purple loosestrife or glossy buckthorn. Those three are the most troublesome along Maine’s coast, says Aleta McKeague, an Acadia National Park botanist who leads the exotic plant management project. She will lecture on invasive species and how to combat them Tuesday, Oct. 19, at 7 p.m. in Moore Auditorium at the Schoodic Educational Research Center in Winter Harbor. The park is seeking additional volunteers to cut back or root out these alien plants. Most of that work takes place in the growing season and resumes next May, but now is a good time to learn about the plants.
Japanese knotweed by this time has lost its triangular leaves and stands up to 13 feet high as fat, green, red-flecked stalks with joints that make them look like bamboo. Gardeners are said to have brought it to this country as an ornamental plant and for use in erosion control. But it spreads quickly and forms thickets that crowd out native vegetation and clog waterways.
Purple loosestrife is a shrub that stands 3-10 feet tall and can form thick mats along ditches and streams. Its stems are green to purple. A single stem can produce more than a million seeds a year, so uprooting it should take place before the seeds fall.
The glossy buckthorn is a large shrub or a small tree that can grow up to 20 feet and forms dense stands that can choke out other plants.
Park botanists suggest that people consult the Internet for descriptions and pictures of invasive plants. They cite particularly www.invasive.org, but other web sites are also easily found by searching for specific plants.
Many of the alien plants that cause so much trouble were brought in deliberately and cultivated. The buckthorn has been used to form hedges and keep out wildlife. But most of these foreign plants thrive in a new habitat that lacks the competing plants that originally kept them under control.
Other invaders are brought to this country in ship cargoes and as seeds caught in the shoes of travelers from abroad.
Still other threats are the invasive aquatic plants that threaten Maine’s lakes and streams. The Maine Volunteer Lake Monitoring Program involves more than 2,000 volunteers, state officials, teachers and students. The Invasive Plant Patrol program conducts free workshops to train volunteers in prevention, early detection and rapid action against the invading species.
David Pimentel, Cornell University professor of ecology and agriculture, reported that invasive plant species cost the United States $34 billion a year in damage and control efforts. When animals, insects and other invaders are considered, he puts the total cost at more than $200 billion.
Volunteers will be saving big money as well as helping protect natural beauty.