1 PEOPLE SPREAD INVASIVE SPECIES Invasive species are a worldwide problem A plant animal or microorganism species that thrives in an area outside its normal territory is called invasive It does not belong there Invasive species can cause great harm They compete with other species for food shelter and other natural resources Most have been introduced by humans Historically humans have introduced invasive species while traveling or invasive species while traveling or exploring Sometimes they brought species with them on purpose Early colonists to North America carried plants seeds and animals from Europe Such species include cows and horses Other plants animals insects and microorganisms hid in crates They were accidentally introduced to North America Asian tiger mosquitos were introduced to the United States by accident 4
A sign warns boaters to watch for invasive zebra mussels Today humans continue to introduce invasive species both on purpose and by accident Some such as the kudzu vine were introduced to provide food for animals and humans Others such as the Burmese python were brought into their new habitats as pets When they escape or are released they cause problems for other species Humans try to manage invasive species They may physically remove them Or they may use chemicals or other species to kill the invasive species 4,300 Invasive species currently in the United States Early colonists brought many invasive species to their new homes Invasive species alter habitats by competing with native plants and animals Invasive species can be pets that have escaped or been released into the wild THE EARLIEST INVADERS Humans were the first species to spread outside of their original territory Humans first emerged from Africa 50,000 to 70,000 years ago Gradually they spread across the globe Early humans brought invasive species with them They brought possums and dogs to Indonesia They introduced dingoes to Australia 5
2 KUDZU IS THE VINE THAT ATE THE SOUTH Kudzu is a climbing vine native to Asia People eat its roots and use its stems to make fibers It has been used for thousands of years as medicine too Kudzu was introduced to the United States at the 1876 Philadelphia Centennial Exposition It was promoted as a decorative plant and as livestock feed In the 1930s farmers in the South used kudzu as ground cover to help prevent soil erosion By the mid-1940s kudzu had been planted on 1 2 million acres 486,000 ha Kudzu is fast growing and spreads quickly It can grow up to 1 foot 30 cm per day Its thick roots can 6 The kudzu vine e The kudzu vine The kudzu vine e ud u covers everything in covers everything in covers everything in its path its path its path its path
Scientists try to control kudzu with chemicals extend 12 feet 3 7 m into the soil and weigh up to 400 pounds 181 kg The roots can store a lot of water The plant is very hardy and can survive in both sun and shade However it thrives best in full sun and warm temperatures That is why it grows especially well in the South After farmers used it to prevent erosion it quickly started taking over It overruns anything in its path Since it is a climbing vine kudzu can cover trees and telephone poles Places that are abandoned or neglected are especially at risk Kudzu crowds out other plants for space and nutrients If left to grow the vine is very difficult to destroy People call kudzu the green menace and the mile-a-minute vine They also call it the vine that ate the South 100 Length in feet that a kudzu vine can grow Kudzu was brought to the United States as a decorative plant and for livestock food It was used in the South to battle soil erosion Kudzu has extremely strong deep roots The plant has many nicknames including the vine that ate the South 7
