Combatting Invasive Species
On their home turf, plant and animal populations are kept in check by natural controls, like predators and food supply.
However, when a species is introduced, accidentally or intentionally, into a new landscape — one not adapted to its presence — the consequences can be devastating. Not all of these "non-native" species misbehave. But some non-native species spread unchecked, disrupting natural cycles, crowding out native species and costing billions in property damage and lost economic productivity.
These are known as "invasive" species.
The Problem of Invasive Species
The sudden introduction to a new landscape of a foreign species, one free from natural competitors and predators, can cause ecological chaos.
The first brown tree snakes were seen on Guam in the mid-1950s, for instance, likely arriving from their native New Guinea as cargo stowaways on U.S. military ships during World War II. Guam's birds made easy prey for the eight-foot serpent, which extirpated 12 bird species on the island, some found nowhere else in the world. Brown tree snakes now threaten to invade Hawaii and other Pacific Islands.
Invasive plants can be just as damaging as animals, outgrowing native plants, hoarding much-needed light, water and nutrients, and sometimes even altering soil chemistry, pushing native species to the brink of extinction.
Invasive species are appearing around the world at an unprecedented rate and scale. Some are introduced intentionally: large and costly infestations of purple loosestrife, scotch broom and water hyacinth resulted from gardeners planting these species for their bright showy flowers. Anglers and game managers introduced the flathead catfish to rivers beyond its native range, and these behemoths are now making easy prey of some of America's most endangered native fish.
Others take hold accidentally: a Caspian Sea tanker dumped its ballast water — and the Asian zebra mussel — into the Great Lakes a little more than a decade ago. Now the tiny mussels threaten to smother 140 native mussel species, and waterfront industries, like dams and power plants, must pay billions in on-going repairs to clogged pipes while passing the cost to consumers.
The Asian longhorned beetle hitchhiked to New York, New Jersey and Chicago in solid wood packing crates from China, where it escaped and has prompted the cutting, chipping, and burning of over 8,000 street and yard trees at considerable cost. The beetle attacks maples and other hardwood species, threatening the timber, maple syrup, nursery, and fall foliage tourism industries across the Northeast.
The Consequences of Invasive Species
Invasive species contribute directly to the decline of 49% of the threatened and endangered species in the United States. Only habitat loss poses a greater threat.
The entire island chain of Hawaii has been devastated by an onslaught of foreign insects, snakes, plants and pests. Feral pigs trample delicate nesting birds, rosy wolfsnails gorge themselves on the island's native snails, miconia plants shade out native plants and hurt water quality, and coqui tree frogs aggravate tourists and depress home values with their piercing calls.
No type of habitat or region of the globe is immune from the threat of invasive species. Aquatic and estuarine systems are especially vulnerable, and invasions in these ecosystems are harder to contain and reverse. Introductions in New Zealand have resulted in that country creating the strictest laws against non-native species in the world.
Invasive species also exact heavy costs in lost economic productivity.
In North America's Great Plains, for instance, ranchers and natural area managers have combined forces to battle leafy spurge, a Eurasian invader that has infested about 5 million acres across the region. It overtakes prime livestock pasture, chokes out native grasses and is impervious to conventional attempts to destroy it. Cattle and other grazers refuse to eat it because of its poisonous milky sap.
The U.S. Department of Agriculture estimates the leafy spurge plague costs ranchers in the Dakotas, Montana and Wyoming more than $144 million a year in losses. In 1998, Secretary of the Interior Bruce Babbitt reported that all invasive weeds combined caused ranchers $5 billion in lost productivity annually.
The Nature Conservancy's Invasive Species Initiative aims to control the threat to biodiversity posed by invasive non-native plants, animals, insects, and diseases through a combination of prevention, early detection, eradication, restoration, research and outreach. The Conservancy believes that the threat of invasive species can be effectively abated by using these techniques and approaches.
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Comments: 3
I remember once we had a terrible epidemic in the orange and lemon trees here and all over Attica and they said it was again due to some invasive species parasite.
Now we have a problem with the pine trees, they get something like white foam on them, not quite sure though if this is due to an invasive thing or not, but it certainly destroyes the trees very badly (dry out) and there is no way to combat it.The only thing that kills it is so toxic it kills everything so they have resorted to water under pressure to clean them out, but this is only a relief measure.