Despite their significance, plants are simply underrepresented in this report because the data are lacking. The report begins with birds, the single group for which we have the most data at national and large-scale levels. Because of the significance of birds as important migratory species, there has been a strong role for federal research scientists as well as scientists from state agencies and from Canada and Mexico. Some of the best long-term scientific information on status and trends comes from the Breeding Bird Survey and the Christmas Bird Count. We have also included information on ecosystems and ecoregions.
Ecosystems are groups of plants and animals and their nonliving environment such as air and water.
For example, one can speak of a coastal wetland ecosystem, whether in North Carolina or Florida, and understand that it includes several specific features or processes shared by all coastal wetland ecosystems. Ecoregions are geographically defined ecological units, often containing several types of ecosystems, that share common topographic, climatic, and biotic characteristics. Each ecoregion, such as Alaska or Hawaii, can be defined as a single, individual unit on a map, while ecosystems, if mapped, would be scattered about as separate units. The proliferation of introduced species, both plant and animal, has had a profound influence on the native biota of this country. Many human activities, such as pollution and urbanization, both directly and indirectly affect the health of our living resources.