Non native(introduced),exotic species and their impacts to the Essay

Non native(introduced),exotic species and their impacts to the ebvironment - Essay Example For example, U.S. Executive Order 13112 defines invasive species as â€Å"an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health† (Clinton, 1999). Non-native species either can be introduced unintentionally and accidentally or can be transported by humans intentionally and purposely. It is estimated that more than 50,000 non-native species have been introduced into the United States. Many of these introduced species are beneficial, such as â€Å"corn, wheat, rice, and other food crops, and cattle, poultry, and other livestock† which â€Å"provide more than 98% of the U.S. food system at a value of approximately $800 billion per year† (Pimentel, Zuniga, & Morrison, 2005). Some introduced species also are used for â€Å"landscape restoration, biological pest control, sport, pets, and food processing† (Pimentel et al, 2005). However, there are many invasive species with harmful economic, ecologica l or human health impacts. One study estimated â€Å"approximately $97 billion in damages from 79 exotic species during the period from 1906 to1991† (Pimentel et al, 2005). ... ?survives from one growing season to another by forming perennating buds (surviving from season to season) and enduring a period of dormancy during the winter† (â€Å"NYIS.INFO†). Mature giant hogweed can reach a height of 3 to 5 m with hollow stems approximately 5 to 10 cm in diameter and compound leaves as big as 1.5 m (Nice, Johnson, & Bauman, 2004). Giant hogweed has aggressive, invasive and toxic nature and so, it is on the Federal Noxious Weed List (Nice et al, 2004). Originally, giant hogweed belongs to the Caucasus region of Eurasia. Because of its beauty and huge size, in 19th century giant hogweed was introduced to Great Britain as an ornamental curiosity in the 19th century. Later, the plant was imported to the United States â€Å"as a showpiece in arboreta and Victorian gardens (one of the plant’s first North American plantings of giant hogweed was in gardens near Highland Park in the City of Rochester, New York)† (â€Å"NYIS.INFO†). Ever since, giant hogweed has spread in many areas, including Broome, Cattaraugus, Cayuga, Chautauqua, Erie, Genesee, Herkimer, Jefferson, Lewis, Livingston, Madison, Monroe, Nassau, Niagara, Oneida, Onondaga, Ontario, Orleans, Oswego, Putnam, Schuyler, Steuben, Tompkins, Wayne, Wyoming, and Yates Counties in New York; Connecticut; the District of Columbia; Illinois; Maine; Maryland; Massachusetts; Michigan; Ohio; Oregon; Pennsylvania; Washington; Wisconsin; and Ontario and Vancouver Island in Canada (â€Å"NYIS.INFO†). Giant hogweed has ecological and human health impacts. Colonies of this plant easily become dense â€Å"owing to the plant’s prolific seed production and rapid growth rate† (â€Å"NYIS.INFO†). Due to its deep taproots and huge leaves, giant hogweed hinders the growth of native plants by denying them light and