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APES Ch. 9 Chapter Review, Data Analysis, Critical Thinking

Terms in this set (20)

Many introductions of nonnative species have been beneficial to us. According to a study by ecologist David Pimentel, nonnative species such as corn, Wheat, rice, and other food corps , as well as some species of cattle, poultry, and other livestock, provide more than 98% of the U.S. food supply. Similarly, nonnative tree species are grown in about 85% of the world's tree plantations. Some deliberately introduced species have helped to control pests. And highly beneficial European honeybees were brought to North America in the 1600 s by English settlers who harvested the bees' honey and used the wax from their hives to make candles. The problem is that, in their new habitats, some introduced species do not face the natural predators, competitors, parasites, viruses, bacteria, or fungi that had helped to control their numbers in their original habitats. Such nonnative species can thus crowd out populations of many native species, disrupt ecosystem services, cause human health problems, and lead to economic losses. When this happens the nonnative species are viewed as harmful invasive species. Invasive species rarely cause the global extinction of other species, but they can cause population declines and local and regional extinctions of some native species. Many unwanted nonnative invaders arrive from other continents as stowaways on air craft, in the ballast water of tankers and cargo ships, and as hitchhikers on imported products such as wooden packing crates. Cars and trucks can also spread the seeds o f nonnative plant species embedded in their tire treads. Many tourists return home with living plants that can multiply and become invasive. Some of these plants might also contain insects that can invade new areas, multiply rapidly, and threaten crops.