It's because they have adapted to local soil and weather conditions. As a result of their shared history, native vegetation attracts native species of butterflies, insects and birds. At the same time, native plants are subject to native predators, parasites and diseases that also share a part of their history. In the marine environment, you only have to walk at low tide on any Pacific Northwest beach to see special associations among organisms. Native eelgrass, Zostera marina, provides the perfect nursery habitat for young fish, a substrate on which snails lay eggs, a home for Dungeness crab and a food source for brant geese.
American agriculture is based almost entirely upon introduced species.
The most beneficial introductions in American history have concerned land animals and plants and those have almost entirely been associated with agriculture. There are reasons why this is so. All of the animals and plants used in agriculture had been observed in use and in close proximity for millennia. Reprinted with the permission of William Steirer and South Carolina Sea Grant Consortium.