U.S. Biodiversity Survey Finds Surprising Richness of Species

The United States is home to at least twice as many native species of plants, animals and other wild things -- more than 200,000 in all -- than had previously been thought, according to what may be the most comprehensive survey of biological diversity ever undertaken in America.

The nation was also found to harbor a more varied array of ecological systems than any other large country.


Conservation experts characterized the findings as an unexpected piece of good news. But as many as one-third of the country's species are considered imperiled to one degree or another, according to the study, whose details are to be disclosed in Washington today by the Nature Conservancy, whose membership of more than a million makes it the nation's largest private conservation organization.


Five ``hot spots'' -- that is, places where high numbers of species found nowhere else are at risk -- emerged from the analysis: the Bay Area; Southern California; the Death Valley region; the southern Appalachians; and the Florida Panhandle.

The inventory of species was conducted during the past 25 years by the conservancy's Natural Heritage Network, made up of survey centers in all 50 states, most of them parts of state governments and universities. The network's database on species and ecosystems is widely viewed as the most detailed in the nation and is the country's leading source of biological information for conservation planners, government agencies and land managers.

But until now, the information gleaned from the network's extensive field surveys and other sources, such as museum collections and scientific literature, had never been pulled together to produce a portrait of the status of wildlife in the United States.

The analysis found that the 50 states contain about 10 percent of all known species on Earth, and that the United States ranks at or near the top among nations of the world in its variety of mammals (mostly small ones), freshwater fishes, salamanders, mussels, snails, crayfishes and needle-leafed evergreens such as pine trees.

Among insects, by far the most numerous group of species, there were many interesting surprises. The United States, for instance, turns out to be extremely rich in bees, with nearly 4,000 native species, most of them solitary rather than swarming creatures. And the United States harbors more species of caddis flies, mayflies and stoneflies, which are aquatic insects that support many freshwater ecosystems and are beloved by trout fishermen, than any other country.

Meanwhile, according to the survey, the United States has a wider array of ecological regions -- big, distinctly different swatches of nature such as deserts, various kinds of forests, grasslands and tundra -- than any other of the world's six largest countries. By one calculation cited in the study, the United States includes 21 of 28 different types of ecological regions worldwide, five more than its nearest rival, the former Soviet Union.

So lush and variegated is the new portrait of biological variety in the United States that the conservancy will also announce today its commitment of $1 billion to its long-established effort to protect the wild landscape by buying up large parcels of land or securing conservation easements on them.

``I think we've described biodiversity in a way that it's never been described before,'' John C. Sawhill, the conservancy's president, said of the study.