U.S. Biodiversity Countered by Species at Risk

By Cat Lazaroff

ARLINGTON, Virginia, April 23, 2002 (ENS) - Almost one quarter of U.S. states are facing the possibility of losing at least 10 percent of their native species, finds a new report from the Nature Conservancy. The report, released on Earth Day, examines the status of more than 21,000 wild plants and animals and ranks each state by both its biodiversity, and the risks to that biological wealth.

The report, "States of the Union: Ranking America's Biodiversity," draws on ongoing species inventories conducted by state natural heritage programs. The data was analyzed for The Nature Conservancy by NatureServe, a non-profit organization that provides scientific information about rare and endangered species and threatened ecosystems.

gnatcatcher

This threatened California gnatcatcher inhabits increasingly rare coastal scrub lands. California topped the list for species diversity, but also for species at risk. (Photo courtesy U.S. Fish and Wildlife Service)
"This report holds both hope and peril," said Steve McCormick, president of The Nature Conservancy. "As an important snapshot of the biological health of our nation, it shows the extraordinary richness of the flora and fauna across all 50 states. But it also serves as a stark reminder that too many of these species are at risk of vanishing forever."

The report ranks all 50 states and the District of Columbia on several key biological characteristics including diversity of species, distinctiveness of the animals and plants, levels of rarity and risk, and species already lost to extinction.

Many of those characteristics are linked. The report finds, for example, that the state of California ranks in the top five in each category, with the most diversity and largest number of native species (6,717). However, California also rates second for its number of rare and at risk species, and third for the number of species already lost to extinction.

Several states show up in three of the four categories. Hawaii, for example, ranks second for number of native species, but first for both at risk species and already extinct species.

Alabama, which came in fifth in species diversity, ranks in the top five for both at risk species and extinct species. And Texas, which was second in diversity and third for number of native species (6,273), ranked fourth for number of extinct species.

"The report highlights the interplay between the nation's natural history and human history, and provides insights into the scale of the nation's conservation challenges and opportunities," said Dr. Bruce Stein, the author of the report and a senior scientist with NatureServe.

Stein notes that most of the areas with the greatest species diversity are found in the southwest, with its diverse landscapes and climate. This is due in part, he said, to the enormous size of diversity leaders California and Texas, their ecological complexity and their location along the country's southern border.

akiapolaau

The `Akiapölä`au, which lives only on the island of Hawaii, is at risk from ongoing habitat destruction. Hawaii ranked first in number of species at risk, and number already lost to extinction. (Photo courtesy Earthjustice Legal Defense Fund)
Risk patterns among states - as reflected by the proportion of a state's species considered imperiled or vulnerable - highlight Hawaii, where 63 percent of species are at risk, and California, with 29 percent of species at risk. Other centers of rarity are found in several other western and southeastern states including Nevada (16 percent), Alabama (15 percent), Utah (15 percent) and Florida (14 percent).

McCormick noted that 12 states -- or almost a quarter of the country - have more than 10 percent of their species classified as rare or at risk of extinction.

"This demonstrates that we will never be successful at protecting biodiversity if we concentrate our conservation efforts in small patches here and there," McCormick said. "We must protect large landscapes and work collaboratively with a wide array of interests. That means working with federal, state and local governments as well as private property owners so that land is managed in a manner that helps, not hurts biodiversity."

Although extinctions have touched every state in the nation, the report shows that certain regions have lost disproportionate numbers of species. Stein notes that states with a large number of extinctions tend to have either high overall species numbers, an inherently fragile flora and fauna, or intense human alteration of the landscape.

Hawaii has suffered the gravest losses, with 217 presumed or possibly extinct species. On the mainland, Alabama tops the list of extinction prone states with 90 species, many of which existed in freshwater systems. Many of the state's waterways have been dammed, dredged, or diverted, leading to the loss of numerous snails, mussels and fishes.

California ranks third in the nation with 53 extinctions. Stein said the intensive conversion of the state's land and waters for agriculture, urbanization and other uses has had a severe impact on the many rare and geographically restricted species that have evolved in this ecologically unique state.

mouse

The endangered Alabama beach mouse is one of the many species that pushed Alabama into the top five for at risk species and extinct species. (Photo by Nicholas Holler, courtesy U.S. Geological Survey)
California, with 1,295 native species that are unique to the state, leads the nation in this category, according to the report. This is a result of its large size and the complexity of natural habitats in the state.

Stein said Hawaii also stands out for the distinctiveness of its flora and fauna. Because of the island chain's extreme isolation, most plants and animals native to the archipelago are descended from a relatively few colonists.

The report also looked at species diversity broken down by species categories, which revealed distinctive, and at times strikingly different patterns. For example, while the large and ecologically varied southwestern states again lead the nation in plant and mammal diversity, amphibians and freshwater fishes reach their highest levels of diversity in the southeastern United States.

With its combination of Appalachian highlands and humid coastal lowlands, the southeastern region is a global center for freshwater diversity.

Bird and reptile diversity is more geographically mixed, with both eastern and western states represented in the top tier. Texas, which straddles both east and west, leads all other states for both groups.

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About two thirds of the nation's species are "apparently secure," meaning there is no evidence showing them to be at risk. (Photo courtesy The Nature Conservancy)
The study supports the idea that entire ecosystems need protecting, the Nature Conservancy says.

Using data from organizations like NatureServe, Nature Conservancy scientists undertake a detailed planning process called ecoregional planning in which they identify threats to species and determine what conservation activities need to be undertaken to protect them. The Conservancy then works in partnership with communities, government, business and property owners to implement conservation strategies to protect species.

"Ecoregional planning and the protection of whole functional landscapes provide us with the ability to reduce the number of species at risk," McCormick said. "This will not be an easy task, but future generations will judge us on our ability to succeed."

More information from the report, which updates information in the book "Precious Heritage: The Status of Biodiversity in the United States," published in 2000 by The Nature Conservancy and NatureServe, is available at: http://nature.org/earthday/files/states_of_the_union_report.pdf