Out
On A Limb / September 2006
Return of the Natives
|  Water Shield
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West Virginia woodlands, traditional reservoirs of natural beauty and delicate diversity, are being slowly, sadly transformed into jungles of kudzu, buckhorn and garlic mustard. The diverse wildflowers of the state are being lost in the process. Trilliums, Jack-in-the-pulpits, ferns, lady’s-slippers, shooting stars, wild geraniums, May-apples, trout lilies, Dutchman’s breeches, and other treasures will be gone forever unless more is done to save them soon.
The lush, green landscapes often associated with invasive plants, like kudzu, create the illusion of a vibrant, flourishing ecosystem when, in fact, many species have been lost and complex natural processes are being disrupted.
Invasive plants often get started in areas disturbed by human activities like road building, timbering or mining that remove native vegetation, disturb soil, or affect the amount of sunlight or moisture to the land. Only a small number of invasive species have moved into natural areas, but the species reproduce rapidly, forming stands that exclude other plant species. In the worst cases, they radically alter the ecosystem processes and displace native species.
The number of non-native invasive plant species in West Virginia is rising
663 species of vascular plants in West Virginia are non-native. Each year the number of plant species and the threats they pose to natural communities.
 Kudzu |
The incredibly invasive Purple loosestrife, Lythrum salicaria, has destroyed thousands of acres of wetland habitat but the plant with tall spikes of purple flowers is still purchased as an ornamental. It has blanketed emergent wetlands along the Ohio River, and is increasing along other major rivers, replacing native vegetation, threatening rare plant species, and destroying small wetlands.
Tree-Of-Heaven is a significant threat to timberland and has already invaded thousands of acres of forestland. Once established, it forms impenetrable thickets and prevents native trees from growing back. Tree-of-heaven can grow eight feet in one year and when cut down, sprouts multiple new growths from its roots.
Mile-a-minute, a spiny, trailing vine that climbs up to twenty feet into trees, smothers native shrubs and shades out herbaceous plants along rivers. Mile-A-Minute may grow faster than Tree of Heaven, up to ten feet in a year, over shrubs and trees, blocking sunlight to every plant under it.
In the 1950s Crown vetch was introduced from Asia as a ground cover for erosion control. The lovely but aggressive plant invades sunny habitats, climbing over small trees and ground cover and shading them out.
The creeping vine called kudzu grows a foot a day, extending nearly 60 feet in a growing season over shrubs and trees, strangling branches and smothering foliage. In a few years, acres of wildlife habitat vanish. Kudzu was introduced to the U.S. from Asia in 1876, promoted first as a forage crop for livestock and an ornamental plant and in the 1930s, as a control for soil erosion. By 1953, it was a weed gone wild.
 Purple Loostrife |
Common buckthorn overwhelms native oaks because oaks are unusually sensitive to intense shade as saplings. When the older trees eventually die, there will be no young oaks available to replace them.
Other native trees, like hickory, ash, beech, butternut, sugar maple, cherry, or elm will also ultimately lose in the competition against buckthorn.
Water shield, a small water lily with thick growth and purple flowers, first appeared in West Virginia lake about 30 years ago. Now it occurs in bodies of water across the state. Pendleton Lake at Blackwater Falls, was recently drained in an attempt to kill the plant.
Reed canary grass is a large, sod-forming grass that has taken over hundreds of acres of wetland habitat, displacing diverse native plants that provide food for waterfowl and serve as host plants.
Japanese stiltgrass seriously threatens forest understory habitat. A packing material in boxes of porcelain imported from China in the early 1900s, it probably escaped into the wild when people disposed of the dried grass. It can completely displace hundreds of species of wildflowers and prevent the growth of tree and shrub seedlings.
Like Japanese stiltgrass, garlic mustard invades the forest floor, monopolizing light, moisture and nutrients.
The economic impact of invasive weeds in the US is staggering, over $35 billion a year. Leisure activities are affected as well as forestry and agricultural production. Invasive weeds are often thorny, poisonous, or too dense to get through, so they limit access to recreational areas and overtake desirable land sites.
Most native plant species were here when North America was first settled by Europeans. In the normal course of events, arrival of new species would be the result of a hurricane, or of gradual change over thousands of years. Humans vastly accelerated plant movement, carrying thousands of species that couldn’t naturally cross oceans or mountain ranges to new areas. Those species are the non-natives.
However, native stock plants are becoming available. Native alternatives are being explored for conservation purposes and nurseries are being encouraged to cultivate native plants for ornamental projects.
Invasive plants destroy wildlife habitat and food sources Since insects and small mammals depend on hundreds of species of native plants, and larger mammals depend on the smaller ones for food, a single invasive species may displace a whole ecosystem. Wildlife that has evolved with native plant species, needs those plants for survival. When invasive weeds devastate the diversity and quantity of native plants, very soon, they devastate the diversity and quantity of native wildlife as well. PL
Copyright © 2005-2006 A Woman's View. All rights reserved.
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