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| Alien Invaders By Hal Brown The bright red and pink leaves of the "burning bush" are the last hangers-on of the fall foliage. It's a handsome, hardy plant, early to bloom, easy to raise and popular with gardeners in years past. It's also a threat to Connecticut's woodlands. "You can see it now in the understory as you drive along the roads in Norwalk and Wilton and Ridgefield. Everything else has lost its leaves, and it's still going on," said Greg Waters, a horticulturist at Weir Farm National Historic Site on the Ridgefield-Wilton border. "It has beautiful color in the fall, so people like it and they tend to plant it in their gardens, but it has multiple, multiple seeds, and the birds take those seeds and drop them all over the place." Burning bush, also known as winged euonymus, and a growing number of other non-native, invasive plant species "could be as harmful to the environment as unchecked pollution and inappropriate development," said state Department of Environmental Protection Assistant Commissioner David Leff in a news release issued earlier this year. For many people, though, invasive plants aren't even a blip on the environmental horizon. Waters was to lead a tour for the Norwalk River Watershed Association in late October to show the public invasive plant problems and methods of dealing with them, but no one showed up. "It's an important issue, but not a popular one," Waters said. The alien plants "are putting great pressure on the native flora," Waters said. "They compete for space, they compete for nutrients in the soil, they compete for sun. "The invasives tend to have a large amount of seeds, and a lot of them are spread either by the wind or by birds. They tend to grow quickly, and they tend to have a very short cycle from seed to maturing plant. The seed might be planted one year, and the following year they're able to reproduce more seeds." In some cases, they're beating out native species, which can be a problem. "They estimate something like 40 percent or 50 percent of the threatened and endangered species have some kind of relationship with some invasive plant or animal that's come in," he said. "The types of [invasive] plants we have in this area are mainly shrubs and some vines," Waters said. "Basically the problem is a lot of them are garden escapees - they started growing in people's gardens - and a lot of them are exotic; they came originally from Europe or Russia or some other country. They got started in the garden and have escaped into the woodlands and fields." In forested areas, trees like Norway maple and vines like Japanese honeysuckle grow into the canopy of other trees and can shade them out or topple them, said John M. Randall, a specialist in invasive weeds for The Nature Conservancy, writing on a Brooklyn Botanical Gardens Web site. "Shrubs like bush honeysuckles and buckthorns take over the forest mid-story while herbaceous species like garlic mustard colonize and dominate the ground layers," he wrote. One study shows that invasive plant species are likely to have relatively small amounts of DNA in their cell nuclei, Randall wrote. "Apparently the cells in these plants are able to divide and multiply more quickly and consequently the entire plant can grow more rapidly than species with higher cellular DNA content. This gives them a leg up in disturbed sites." The Connecticut Geological and Natural History Survey includes a list of 88 plants that are invasive or potentially invasive. Ken Metzler, an ecologist with the survey, said nurseries still carry plants that could present problems. Burning bush, for example, still can be found for sale. Norway maple, particularly a problem in coastal areas, is "very widely cultivated in the nursery trade," he said. Nurseries and gardeners aren't the only sources of invasive plants. Autumn olive was introduced by the state for highway plantings. Other plants that are alien to Connecticut and invasive include Japanese barberry, garlic mustard, Asiatic bittersweet, black locust, multiflora rose, purple loosestrife and water chestnut. False indigo, yellow iris, forget-me-not, Russian olive and several species of privet also are invasive. Even kudzu vine, the scourge of the South, is in Connecticut. Les Mehrhoff, with the University of Connecticut, said although kudzu is not a big problem here because of New England's climate, "it's probably only a matter of time before a cold-resistant variety appears" and the rampant vine starts to spread. Waters said ridding the landscape of the unwanted plants presents varying degrees of difficulty. Some, like Japanese barberry, can be pulled by hand, he said. Bittersweet, autumn olive and bamboo-like plants such as knotweed are harder to eliminate. "You cut them multiple times," Waters said. "If you cut them three or four times, you weaken them so they eventually will die, or you can go to using herbicides." Grubbing out plants doesn't always work, he said. Some can regenerate from pieces of root only a couple of inches long. Metzler said the long-term effect of unchecked invasives is to create a plant monoculture. In the instance of the common reed, a marshlands invader, this means that the adopted habitat has fewer bird species and fewer invertebrate species. Waters said a monoculture poses other problems as well. "Take a typical understory situation in Wilton or Ridgefield where barberry or burning bush gets in there and it pretty much takes over. When you have a woods filled with just one species, all it takes is one disease or insect problem to wipe it all out," he said. "If everything dies, then there's erosion. We can't really answer all the questions about the long-term effects." To help forestall problems, Metzler said the Connecticut Invasive Plants Working Group, composed of academics, nurserymen and landscapers, "is trying to come up with alternatives or replacements" for alien plants. "There are a lot of plants that are problematic, that have traditionally been used for landscaping or roadside decoration, wildlife enhancement, whatever," he said. "We're trying to come up with a number of suggested plants that would function the same way but would not be a danger, plants that won't spread or have the berries that provide overwinter food for birds or whatever." Waters emphasized that invasive species "are a severe problem" here. "I have been around this area of Connecticut for eight or nine years, and I have seen a big change in what's along the roadsides and in the understory," he said. "Some of the plants I've mentioned have really gained a foothold or are increasing rapidly." |
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| Second Place Winner New England Press Association Writing contest 2001 Environmental Writing |