Nipping plant interlopers in the bud
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By Lisa Capone

LESLIE MEHRHOFF tends to drive off the road on purpose. With an eagle eye for out-of-place plants, Mehrhoff has been known to pull over and dash across highways to yank foreign weeds from median strips. Once, glimpsing a flash of yellow on the opposite side of the Maine Turnpike, he got lost in Portland trying to reverse direction to reach a patch of leafy spurge. Noticing the same Eurasian species growing in a crack of asphalt on Route 84 in Ashford, Connecticut, he stopped to snap off the offending stems three years in a row.

“Driving with me is fun,” quips Mehrhoff, who is curator of the University of Connecticut-Storrs Herbarium. “I know people who will not do it.”

Mehrhoff is passionate about plants but not in a fill up the garden with lovely perennials sort of way. As director of the Invasive Plant Atlas of New England (IPANE), he heads a six-state, 600-volunteer effort that is mapping roadsides, meadows, hilltops, coastlines and ponds where aggressive intruders threaten to out-compete native plants and tip the balance of terrestrial and freshwater ecosystems. Begun in 2001 with a $1.26 million grant from the U.S. Department of Agriculture, IPANE features an Internet site that lists, illustrates and pinpoints the location of 111 species of invasive or “potentially invasive” plants in Connecticut, Rhode Island, Massachusetts, Maine, Vermont and New Hampshire. Citizens can submit digital images of suspected plant invaders to the Web site (http://ipane.org), and connect with experts who can identify problem species and recommend ways to control infestations before they get unwieldy.

“The overarching goal of this whole thing is to develop an early detection system for New England,” Mehrhoff said during an interview in April at Harvard University's Herbaria. “We're trying to make sure people understand this concept: if they find it when it's small, get rid of it. If we can react to them (invasives) quickly, it will be less expensive and it will have less impact on the environment.”

While a species like Asiatic bittersweet introduced to the United States from China around 1860 is so pervasive that it might never be purged from the New England landscape, time is ripe to nip other plant incursions in the bud, Mehrhoff said. If detected early, isolated outbreaks of less-established interlopers might be eradicated without chemicals that could harm surrounding habitats, he said. Along coastal regions of the Gulf of Maine, species that bear watching include aquatic plants such as fanwort and hydrilla, and salt marsh invaders like common reed (Phragmites) and tall pepperwort, a native of Southeast Europe and Africa that arrived on Massachusetts's North Shore in 1924 and is poised to move into New Hampshire's seacoast region as early as this year.

Mehrhoff points out that not all “non-native” species come under the heading of “invasive.” To be considered invasive, he said, a plant must “be aggressive and it has to be able to become dominant or disruptive to minimally managed ecosystems” such as woodlands, nature preserves, natural ponds and fields.

By tracking the spread of problem species, IPANE helps public and private land managers plan ahead and budget for controlling invasive species that appear bound for their areas, said Randy Westbrooks, national invasive plant coordinator for the U.S. Geological Survey.

“I expect we'll ultimately have a number of (regional) atlas projects like IPANE, so it's really a model as far as I'm concerned,” Westbrooks said.

IPANE's success depends on several partnerships. The New England Wildflower Society in Framingham, Massachusetts has trained 600 volunteers, ranging from college students to senior citizens, said Senior Conservation Programs Manager Christopher Mattrick. About 450 people actively submit invasive plant data from their local areas to the IPANE site, where scientists use it for research and mapping, and to plan control activities. Even people who aren't active volunteers leave IPANE training sessions with heightened awareness of invasive species and “some have become local advocates for (controlling) invasive species in their own cities and towns,” Mattrick said.

An especially important partner in IPANE's work is the New England nursery industry. Many nurseries are phasing out sales of three invasive species popular with consumers: Norway maple, Japanese barberry and burning bush. Pat Bigelow, president of Bigelow Nurseries, Inc. of Northboro, Massachusetts - whom Mehrhoff calls a leader in the field - said she devotes a lot of time to promoting alternative, native species during talks with garden clubs, landscape architects and other groups. She refers to invasive plants as “thugs” with the potential to change native landscapes forever.

“They affect biodiversity and biodiversity is our natural heritage,” Mehrhoff concurred. “To me, it's an issue of environmental change. I'd like to see the natural heritage that evolved on this planet remain. To me, it's part of being environmentally responsible.”

Lisa Capone is a free-lance writer in Melrose, Massachusetts.