Invasive plants not only reduce diversity and mar the scenery, but they also disrupt ecological processes. Wildlife native to Virginia is unfamiliar with non-native plants and will not use them as habitat, regardless of the generous shelter they could potentially offer. Plants and animals that have evolved together have adapted gradually to change, creating a web of life whose balance is delicate.
The seeds and fruits of invasives can be dispersed by wind, birds, hikers’ boots and automobile tires at an alarming rate. Rampant vegetative spread, high seed production and successful dispersal, germination and colonization: all are part of the process by which invasives muscle out native plants. And it is tough and expensive to control their spread.
Species considered “native” are those growing in Virginia before the arrival of the Europeans, usually set at 1607, the time of the settlement of Jamestown. According to Tom Smith, Director of the Natural Heritage program of Virginia’s Department of Conservation and Recreation, “The estimate in the U.S. for annual economic loss due to invasive species is $137 billion per year.” Natural Heritage’s focus is to protect rare plant and animal species, to manage Virginia’s Natural Area Preserve System—land other than areas within the Parks System that provides habitat for rare species. The program’s focus since the early ’90s has been the greatest threat to this habitat, invasives. Governor Tim Kaine recently signed an executive directive that created the Invasive Species Working Group, intended to develop a statewide species management plan. The group has been approved by the U.S. Fish and Wildlife Service, which means it will be eligible for limited federal funding beginning in the fall of 2007.
Citizens can help by understanding what should and should not be introduced into our environment. Infamous intruders such as kudzu are obvious, but some exotics like Oriental bittersweet might seem showy and harmless when they, in fact, are not. Kudzu, native to Japan, was thought to be ornamental when it was brought to the southeastern U.S. to use as a soil stabilizer and animal fodder. In the 1930s, the U.S. Department of Agriculture used it to revegetate areas where the soil was disturbed by construction, to control erosion on bare banks. The highway department liked its ability to grow fast in poor soil; however, its prolific nature—the ability to grow as much as a foot a day and, under ideal conditions, up to 60 feet a year—has made it a feared strangler with its own Little Shop of Horrors. Left alone, it grows into a vast canopy over a whole forest of trees and capturing all the sunlight at the top. Deprived of light, the trees and plant material underneath die. Besides seriously stifling agricultural and timber production, well-established kudzu can take up to 10 years to control, because its root system can be up to 12 feet deep.
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