GREAT FALLS

--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, the 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 inhabited 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.

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.