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Economic
Invasive species can cause a great deal of economic expense. Not only can invasive species be economically expensive for a country, they can also be environmentally expensive. Two species of trees, once widely distributed, have now been essentially wiped out in the U.S. by invasive species of plant diseases. The American Chestnut was once the most dominant canopy hardwood tree in forests in Northeastern U.S., capable of growing 120 feet tall and up to 10 feet in diameter. Its wood was the most economically valuable at the time. Around 1900 several exotic species of chestnut trees were imported and planted in New York City. Along with these trees came fungal disease, the Chestnut blight. During the next few decades, 99.99% - almost 4 billion American Chestnut trees died. Only a few isolated stands of the chestnut survived this environmental catastrophe. During the second half of the 1900's, another plant disease, the Dutch Elm Disease crossed the U.S. destroying over 100 million urban elm tree plantings. Thousands of communities had streets lined with elm trees. The disease currently threatens elm trees in Canada, valued in the billions of dollars. |
