What’s So Bad About Invasive Species?

Who’s native? Who’s not? And are they all unwelcome?

The Vineyard plays host to a number of species that aren’t, historically, from around here. Some of these interlopers behave themselves. But others wreak havoc, displacing valuable native species and transforming fragile ecosystems. Should we fight back?

If you haven’t yet spotted a brown marmorated stink bug on the Vineyard, just wait. MV Atlas of Life director Matt Pelikan has the distinction of being the first to document the interloper’s appearance on the Vineyard in 2018 on iNaturalist, the citizen science social network that shares observations about the natural world. Since then, he says, “they’ve settled in as pretty common around my house, and lots of other people are finding them, too, sometimes in pretty large numbers.” 

But though brown marmorated stink bugs are deemed an invasive species in Massachusetts (and plenty of other locales), they don’t seem to be anything more than a smelly nuisance on the Vineyard — and that’s only if you squash them. 

Pelikan says the word invasive “is really pretty slippery and context dependent. And means different things to different people.”

Suzan Bellincampi, Islands Director, Mass Audubon (and director at Felix Neck Sanctuary), differentiates between native, non-native, non-native invasive, naturalized — “It’s a continuum,” she says, and just because a species is unwelcome, doesn’t mean it’s invasive. 

Stink bugs might be unwanted on the Vineyard but they aren’t, at least not yet, invasive here. Skunks, long the scourge of those of us who just want to walk our dogs at dusk without a stand-off, are believed by most Islanders to have been imported here in the 1960s by a Vineyarder who shall remain nameless. Not so. They are, in fact, natives. “We have multiple sources from the fossil record and historical record to tell us that they were here,” says BiodiversityWorks’ Luanne Johnson (who studied skunks for her Ph.D). 

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The same holds for poison ivy. We all hate it but it was here millennia before we were. 

What do we mean by “invasives”?

“Invasives are plants, animals, organisms that have a negative effect on the ecosystem,” Bellincampi says. “They disrupt beneficial processes, they spread diseases, they alter the ecology.” 

Invasive is a relatively new descriptor. It was in 1999 that President Clinton issued Executive Order 13112 that read, “An invasive species is defined as a species that is 1) non-native (or alien) to the ecosystem under consideration and 2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.”

“Habitat destruction, invasive plants or animals are the leading cause of species extinction,” says Tim Boland, executive director of The Polly Hill Arboretum. “When you have a local extinction, a whole suite of co-dependent lifeforms — invertebrates, micro and macro organisms, etc. — are also correspondingly lost.” And that loss isn’t just ecological, Boland says. It’s aesthetic. The world becomes not only “less diverse and less biologically active, it’s less beautiful.” It’s also personal, he says. “The cascade effect will eventually catch up with the human species.” As much as we like to think we have dominion over the natural world, we are, ultimately, just another species. 

Again, it’s important to make the distinction between non-native species, which often coexist quite nicely with natives, and those that genuinely pose a threat, especially to the Vineyard’s rare ecosystems. 

No habitat is immune to intruding species. They arrive in any number of ways. Some marine species arrive on boat hulls or in ballast water. Seeds are carried here by wind or dropped here in bird feces. Contaminated soil is a huge problem, say, on the roots of that shrub an Islander brought to transplant from New Jersey, or in the bag of soil purchased from Lowe’s. We’ve brought some invasives here (albeit often unintentionally) because they’re beautiful and they grow well in this environment. 

It’s Japanese knotweed that particularly worries Matt Pelikan, who notes that, for the most part, “there aren’t too many insects or animals that I’m terribly concerned about on the Vineyard.” But while a lot of species considered invasive in Massachusetts don’t do well on the Island — “they’re not able to handle the high acidity and drought conditions,” Pelikan says — knotweed is quite comfortable in our unique sandplain soils.

Oriental bittersweet torments Suzan Bellicampi. “I’m going to be 90 years old pulling bittersweet in my retirement,” she says. It’s among the plants strangling milkweed, which Monarch butterfly larvae need for survival. And it isn’t just plants that concern Bellincampi. Green crabs, which likely arrived in tiny zoea form on the hull of someone’s boat or in ballast water, are quickly outcompeting native blue crabs in Vineyard ponds. 

Ecologists and wildlife biologists tell us to expect to see more of what are called ‘range-shifting’ or ‘climate-tracking’ species as climate change makes certain locations more hospitable to some species and less hospitable to others.

Michigan, New York, Pennsylvania, and Minnesota have been sounding the alarm about invasive jumping earthworms, differentiated from more common earthworms by a creamy white band toward its tip. But while worms are typically a sign of soil health, these jumping worms impact the nitrogen, fungi, and soil bacteria, leaving soil that’s been likened to “coffee grounds” and is far less supportive of native species. They’re now here — likely transported in their tiny cocoon stage via soil, or mulch, perhaps even on the bottoms of people’s shoes — and there are reports of them in many Island gardens.

Others on this Least Wanted list include (but are not limited to) Phragmites, invasive honeysuckle (there is a native honeysuckle), and garlic mustard.

Invasives: fight them, or surrender?

But agreeing that invasives are transforming landscapes isn’t the same as agreeing what to do about them.

Indeed, the term “invasive” itself has become loaded. A recent Vox story noted that “‘invasive species’ is a concept so ingrained in American consciousness that it’s taken on a life of its own, coloring the way we judge the health of ecosystems and neatly dividing life on Earth into native and invasive.” 

It’s a binary that invites a vocabulary of war: eradicate, battle, invade, destroy.

There’s a vast middle ground, say ecologists. And it’s growing because of climate change. Species from Miscanthus (silvergrass) to Lone Star ticks are moving from areas where they are well-established, if not technically native, into areas where the habitat might be welcoming but the human inhabitants less so. 

Ecologists and wildlife biologists tell us to expect to see more of what are called “range-shifting” or “climate-tracking” species as climate change makes certain locations more hospitable to some species and less hospitable to others. Luanne Johnson calls them urban adaptors, generalists, synanthropic. “These aren’t invasive species, necessarily. They are simply taking advantage of a landscape we’ve made attractive to them.” And this range-shifting is only going to increase, challenging scientists and the rest of us to consider how, in some cases if, we respond.

Might invasives serve a purpose?

It’s an unpopular opinion (one source says she gets “slammed” if she even mentions it) but it’s worth considering how these invasives might be useful to us. 

Though Phragmites, for example, take over brackish water ecosystems (take a look at the shores of Farm Pond) and do not provide the food or habitat that native plants do, they also absorb more nitrogen than many native plants and help raise the salt marsh base to help protect against sea level rise. 

Emma Green-Beach, a biologist with the Martha’s Vineyard Shellfish Group (MVSG), has a thick folder full of peer-reviewed scientific studies that underscore how effective Phragmites are at nitrogen uptake. For instance, she tells us, an acre of phragmites contains, on average, 100 lbs of nitrogen in its above-ground tissues, equivalent to the nitrogen contained in the edible part of about 130,000 harvested oysters, or an estimated urine-nitrogen output from 11 people in one year. “All around the world, [scientists] have studied these things,” she says. “They've studied the use of Phragmites to clean up wastewater from retention ponds. In Europe, they've been used traditionally like this for centuries. So none of this is a new concept, it’s just not something that is done or embraced around here.”

What has been done by the MVSG is what Green-Beach calls “harvesting” Phragmites. With a grant from the Environmental Protection Agency, the Group monitors Phragmites in small, isolated spots, then cuts them back mid-July or so before they flower. The timing is critical, she explains. If you cut them back too early, they might have time to grow back and flower. What the Group has noticed is that native species are starting to come back. So the Phragmites do the superior work of removing nitrogen but are kept somewhat in check. It’s “making lemonade from lemons,” says Green-Beach, who says that the Phragmites are far too established to be completely eradicated so we might as well turn their presence into a positive while minimizing the negative effects. The experiment hasn’t gone beyond a few small areas but the potential is there, if others can get on board.

In the Midwest, Tim Boland says, Phragmites are chopped to the ground right when they’re starting to flower to weaken them, thereby preventing them from seeding. The biomass gets used as a burning fuel. 

Recently, says Green-Beach, they took some of the Phragmites and had them turned into biochar, which was then given to IGI to use in their fields to improve soil health. “So we continue to chip away at various aspects of this concept,” she says.

—Illustration by Kevin McGrath

Green crabs are being similarly tapped as a resource in places along the east and west coasts of the U.S. and Canada where cooks are putting them on the menu. Researchers at McGill University in Quebec are attempting to create a biopolymer from green crab shells and a partnership between Parks Canada and Nova Scotia’s Dalhousie University aims to turn the crabs into liquid fertilizer. The goal isn’t to eradicate the invasive crabs — that horse is out of the barn, so to speak — but to keep the populations in check and allow native species to thrive and adapt.

On the Vineyard, Emma Green-Beach has heard rumors of a bounty on green crabs. “All the shellfish departments trap green crabs because they are shellfish predators,” she says. “Some give/barter/trade them to conch fishermen for bait. They also make really good compost and a good broth at the least.” 

A recent study by the Johns Hopkins Bloomberg School of Public Health confirms that spotted knotweed shows promise treating Lyme disease in the 25% of sufferers who don’t respond to antibiotic treatment, something Liz Durkee, the Martha’s Vineyard Commission’s climate change planner, says she first heard from Rebecca Gilbert at Chilmark’s Native Earth Teaching Farm. 

Carole Vandal, a Wampanoag tribal member, says Indigenous medicine knowledge, referred to as the “Midewiwin” use herbal medicines to cure illnesses. The Midewiwin is an Algonquin medicine society found historically among the Algonquian of the Upper Great Lakes (Anishinaabe), northern prairies, and eastern subArctic. Vandal says that it instructs us, “If you are ill, go outside and look at the plants in your backyard … often the cure for what ails you can be found right under your nose and feet.”

Indigenous people have long looked at the presence of non-native species opportunities; we should consider how they might be useful, according to Nicholas Reo, an assistant professor of Native American and environmental studies at Dartmouth College. Reo spoke to a Canadian radio show, Unreserved, about a study he conducted to explore how different Indigenous communities were dealing with invasive species. He and his colleagues discovered that, even within communities, there were many different approaches but most centered around traditional knowledge to find solutions. “Indigenous communities seek to build relationships with [invasive species],” Reo said.

“Every plant is a gift from the Creator,” Vandal explains. “We are to respect them and give thanks for their presence.”

If an invasive species is spreading into food gardens and interfering with a person’s ability to feed themselves or their family, Vandal says, “we dig them up and move them to a more suitable place to reside, or sometimes they will be left to die. But the divide and conquer ethos is not our way.”

It’s an approach similarly articulated by Robin Wall Kimmerer, author of Braiding Sweetgrass, professor of environmental biology at Syracuse University, and member of the Citizen Potawatomi Nation. Kimmerer told an interviewer for the Biohabitat site, “When [Indigenous people] look at new or ‘invasive’ species that come to us, instead of having a knee-jerk reaction of ‘those are bad and we want to do everything we can to eliminate them,’ we consider what are they bringing us.” View them as teachers, she urges, noting that “we have created the conditions where they’re going to flourish.”

While there’s little argument that we have, indeed, created the conditions for these species to flourish, the fact remains that valuable native species dwindle when certain new species gain a foothold, leaving us with a dilemma. How do we respond? While Tim Boland agrees with Kimmerer that these losses are driven by humans and that the plants themselves are not inherently evil, “they are evolutionarily programmed to survive and reproduce.” Particularly, he notes, they are opportunists which thrive in damaged or altered ecosystems. 

And we all agree who’s to blame for that.

What You Can Do

While methods to eradicate invasive plant species run the gamut from mechanical removal to applying herbicides — which need to be left to the pros — there are still important ways each of us can help. 

  • Duh … don’t plant invasives.
  • Remove invasives if they’re on your property but do so in a way that doesn’t cause further spreading. Persistently cutting them back will often do the trick. There are some species, such as Japanese knotweed, Phragmites, and Japanese stilt grass, that should be removed only by professionals.
  • Plant native species that support biodiversity, especially pollinator gardens, which attract all kinds of insects.
  • If you have a landscaper, ensure that they have an understanding of the problem of invasive species and a commitment to planting native or non-invasive species.
  • Don’t bring plants, soil, or mulch from off-Island.
  • Embrace messiness. Leave seed heads for birds, leave leaf debris for cocoons and larva.
  • Reduce lawn size and expand garden size.
  • Install bird houses, bat boxes, and owl boxes in close proximity to native plants.
  • Tap into Polly Hill Arboretum’s vast database of native or non-invasive options.

Planting a sustainable yard? Plant this, not that:

Beach plum not Multiflora rose

Switchgrass not silvergrass (Miscanthum)

Bee balm or swamp milkweed not purple loosestrife

Red or sugar maple not Norway maple

Winterberry not autumn olive

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Leslie Garrett
Leslie Garrett
Leslie Garrett is a journalist and the Editorial Director of Bluedot, Inc. Her work has appeared in The Atlantic, Washington Post, Good Housekeeping, and more. She is the author of more than 15 books, including The Virtuous Consumer, a book on living more sustainably. Leslie lives most of the year in Canada with her husband, three children, three dogs and three cats. She is building a home on Martha's Vineyard.
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