Legal and administrative reasons exist to focus on individual species of plants and animals. In addition, various groupings of animals and plants have been constructed, partially in an attempt to simplify ecosystems and make them more easily understood. Some overlap among groups exists. For example, noxious species can have a large economic impact. The bobwhite quail has traditionally been an economic resource and is now a sensitive species over much of the Southeast because of habitat alteration.
Consideration of the groupings here may provide a basis for deciding if a species is significant in the planning context, i.e., species with technical, institutional, or public importance. A significant species may then be used in evaluation of project benefits. The groupings described here may also assist in providing focus for selecting subjects for management or monitoring.