When forest edges become frontlines
Commentary by Carrie Madren
Just after moving into our new home in Northern Virginia, my husband and I set to work on the vine-ridden trees that border our property. Rescuing trees was one of our first forays to help our small part of the watershed return to a somewhat native state. So my first spring task was uncovering a tulip poplar that had grown haphazard, with broken limbs and bowed branches, as a result of its being shrouded by heavy oriental bittersweet.
As spring melded into summer, it became apparent that we were up against a massive force of fast-growing, deep-rooted, thorny flora. Before we knew it, mile-a-minute weed, Japanese stiltgrass and oriental bittersweet blanketed downed branches and open spaces in a stealthy takeover. Woody vines — thick as ropes — tangled with green vines to ensnarl shrubs and small trees.
My husband and I spent weekend afternoons pulling vines, digging roundleaf greenbriar roots, and chipping years’ worth of branches tossed into the thicket. After a bout of poison ivy, countless scratches and weedy mounds of biomass to dispatch, invasive species continued to thrive in areas we hadn’t tackled.
In the mid-Atlantic, invasive plants have spread — by wind, water, animals, tire treads and more — to neighborhood parks, private land,and wildlife refuges alike. In dense urban areas, skinny stream valleys are regularly invaded by invasive plants.
Much of the problem is linked to development: Building a road almost guarantees an entryway for invasion, unless native plants are intentionally planted. Well-used parks and forestlands tend to have the most invasive plant biomass because of more invasive seed introductions. Even mowing down invasives can create enough of a ruckus in the soil to allow other invaders to germinate. Any disturbance in a forest creates an opening for invasive plants to flourish and drop seeds, securing their establishment for another year. Invasive seed banks can produce plants for up to seven years, in some cases.
This replacement of native plants with nonnative plants has far-reaching consequences. As native plants diminish in number and diversity, some insects that feed on native plants also diminish, and up the food chain, birds and other fauna suffer. In suburban and rural areas along the East Coast, overpopulations of deer make matters worse, because they pass over foreign invasive plants to eat the tasty native shrubs.
Across the Bay watershed, the culprits vary — phragmites prefers marshes while English ivy favors upland trees. But results are the same: Over time, they degrade the quality of a forest. In extreme cases, invasives can replace a once-healthy ecosystem with a monoculture of a few worthless non-natives.
Across the country, government agencies and nonprofits are figuring out how to deal with a range of plant invaders, and spending millions to do it.
Controlling the invasive, nonnative plants on your property may seem like a low priority, but doing nothing can offer these invaders a passport to more destruction, seed dispersal to surrounding areas and a diminished quality of ecosystem.
If you do not own a yard — and want to help defend local ecosystems — search for local invasive removal volunteer groups that stop weeds from taking over beloved natural areas. Groups around the Chesapeake watershed clear invasive plants from forests and natural areas to allow native plants to take root once again. These volunteer groups — such as the Weed Warriors of Montgomery County, Md., — fight invasive plants in their local parks season after season.
As a first step, learn to identify the invasive and native plants in your area, so you don’t inadvertently pull up a native plant or allow an invasive to flourish. Figuring out which plants are invasive threats in your own yard will help you become a better steward of your small slice of the ecosystem. Invasive removal trainings — offered by some park systems — can teach you when to grab the clippers and when to use spot treatments of herbicide.
We can also help stop the spread of plant pests by not buying invasive species — such as English Ivy — at nurseries and by talking with neighbors about vine pests that we notice creeping into our yards. We can report to park staff the plant invaders we notice at our favorite park or trail.
In my yard, we’re struggling to tear out invasives by the roots, not let seeds drop, spray larger patches, and nurture the scrawny natives that struggle to survive. It’s a small act, but I know the reward will be a healthy local ecosystem — at least on my turf.
Carrie Madren writes about environmental issues, Chesapeake life and sustainable living. Distributed by Bay Journal News Service.