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published in the 2002 State of the Nation’s Ecosystems Report as well as the 2003 and 2005 Web-Only Updates have been superseded by the 2008 Report and thus should be used with caution.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.

View Data for At-Risk Plant Communities, by Category View Data for At-Risk Plant Communities, by Region

What Is This Indicator, and Why Is It Important? This indicator reports on the percentage of wetland and riparian plant communities that are at different degrees of risk of elimination. These status ranks are based on such factors as the remaining number and condition of occurrences of the community, the remaining acreage, and the severity of threats to the community type. Degrees of risk reported here range from very high (“critically imperiled” communities often are found in five or fewer places or have experienced very steep declines) to moderate (“vulnerable” communities often are found in 80 or fewer places or have experienced widespread declines). Communities ranked as “secure” or “apparently secure” are not listed. In all cases, a wide variety of factors contribute to overall ratings.

Different plant communities (groups of plant species that tend to occur in similar environmental conditions) support distinct species combinations and may provide unique ecosystem values. One community might provide habitat for several rare plant and animal species; another might sequester an especially large amount of carbon.

Why Can't This Entire Indicator Be Reported at This Time? Riparian areas also have characteristic plant communities, but these are less distinct than for wetlands, and there are technical challenges to creating a classification system for riparian areas. Work is under way to develop such a system, which will facilitate future reporting.

What Do the Data Show? About 60% of the 1560 wetland communities ranked here are considered to be at-risk: about 12% are critically imperiled, about 24% are imperiled, and 25% are vulnerable. Hawaii and the Southeast have a larger percentage of at-risk wetland communities, but in all regions except the Northeast, more than 50% of wetland communities are at risk.

Interpreting these figures is complicated, however, because some of these wetland community types have never been widely distributed, while others once covered much larger areas and have been reduced in area by conversion of wetlands to other uses. Because the data do not distinguish between naturally rare community types and those that are declining, this indicator will be much more informative when trend information becomes available. At present, the at-risk plant communities reported here generally occupy small areas and thus probably represent less than 60% of total wetland acreage.