Note that the data published in the 2002 State of the Nation’s Ecosystems Report as well as the 2003 and 2005 Web-Only Updates have been superseded by the 2008 Report and thus should be used with caution. For the most recent data, purchase the 2008 Report from Island Press.

Biological Components: Plants and Animals

Individual species of plants and animals are fundamental building blocks of ecosystems. Species-oriented indicators in this report include those focusing on the percentage of species in particular areas or ecosystems that are at risk of extinction; the degree to which non-native species are gaining a foothold and spreading; and the frequency of unusual mortality events among selected groups of species.

Sixteen indicators relate to plant and animal species, and complete or partial data are available for eight. Three indicators have sufficient data to report trends.

Biological Components: Plants & Animals

Core National At-Risk Native Species Coasts and Oceans At-Risk Marine Species Non-native Species Unusual Marine Mortalities Farmlands Status of Animal Species in Farmlands Areas Native Vegetation in Areas Dominated by Croplands Forests At-Risk Native Species Area Covered by Non-native Plants Fresh Waters At-Risk Native Species Non-native Species Animal Deaths and Deformities Grasslands/Shrublands At-Risk Native Species Non-native Plant Cover Population Trends in Invasive and Non-invasive Birds Urban/Suburban Species Status Disruptive Species

Complete data available Partial data available Data not adequate for national reporting Indicator development needed

Highlights: Plants and Animals

• About 19% of native animal species and 15% of native plants species in the U.S. are ranked as “imperiled” or “critically imperiled”; such species are typically found in 20 or fewer places, may have experienced steep or very steep declines, or display other risk factors. In addition, about 3.5% and 1% of plants are, or are believed to be, extinct. However, because the number of at-risk species is affected both by the number of naturally rare species and by a variety of human activities, it is difficult to interpret these data without information on trends in the number of at-risk species. Trend information is not currently available.
• When species ranked as “vulnerable” are included, about a third of all plant and animal species are “at risk.” The degree of risk for “at risk” species varies considerably, from those species at relatively low risk, to those that are in imminent danger of extinction.
• About 20% of native freshwater animal species are ranked as “imperiled,” as are 9% of forest and grassland/shrubland animals. An ecosystem with a larger percentage of at-risk species does not necessarily have a larger percentage of species that are declining, because some ecosystems have more naturally rare species. Again, it is difficult to interpret these numbers without information on trends, which is not available.
• The only national data on non-native species are for birds and freshwater fish. Only 1% of the 350 major watersheds in the U.S. have no non-native fish; almost two-thirds have between 1 and 10 non-native fish, and the rest have more. In grassland and shrubland areas, populations of invasive and native, non-invasive bird species were changing in about the same proportion for most of the past 35 years.
• About 20% fewer incidents of unusual waterfowl mortality occurred in 1990–1995 than in the previous two 5-year periods. Particularly large mortality events for marine mammals occurred in 1992 (more than 2500 sea lions) and 1999 (215 harbor porpoises and 270 gray whales).