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Gorge Home to 200 Rare Species

Running from Great Falls in Potomac south to Theodore Roosevelt Island in Washington, D.C., the fifteen-mile section of the Potomac River has one of the highest concentrations of globally rare species and communities in the nation.

This according to a joint study between the National Park Service and the Nature Conservancy, which concluded that the Potomac River between Potomac, Md. and D.C., known as the Potomac Gorge, contains more than 400 occurrences of 200 rare species and natural communities.

The assessment of Potomac Gorge was included as part of a larger two-year effort to produce a plan to help manage the natural components of this 9,700-acre area, which is comprised of federal, county, and private lands. The results of the “Potomac Gorge Site Conservation Plan” were released on Earth Day, Monday, April 22, 2002, at Great Falls in Potomac.

Earth Day also marked the debut of new trail signs indicating the partnership between the National Park Service and The Nature Conservancy on Billy Goat Trail in the Chesapeake & Ohio Canal National Historical Park.

“POTOMAC GORGE is an exceptional place,” said Nat Williams, Director of The Nature Conservancy of Maryland/DC. “Plants from as far away as the Plains and the Atlantic Ocean meet here, surviving side-by-side as they do nowhere else. The beauty of this area is no secret, but its biological significance has been.”

An example of the natural diversity of Potomac Gorge can be observed in two plants, the prairie redroot and the climbing dogbane. Prairie redroot is a foot-high plains wildflower whose next closest occurrence is 100 miles away; climbing dogbane is a flowering vine found in the coastal areas of southern Atlantic states. Yet in Potomac Gorge, both species are found within 100 yards of each other at Chain Bridge Flats.

These plants, and over 100 other state-rare species, thrive in Potomac Gorge despite its proximity to the urban bustle of the nation’s capital.

TWELVE PLANTS and four animals in the Gorge are considered globally rare, in addition to the many other more common species that live there, such as bald eagles, scarlet tanagers, fox, butterflies, dragonflies, and a wide variety of fish.

The goal of the Potomac Gorge Conservation Plan is to identify ways in which these plants and animals can be protected at the site while still allowing for recreational use and cultural resource preservation.

C&O Canal National Historical Park occupies almost a quarter of the area in Potomac Gorge. Douglas Faris, C&O Superintendent, said he is mindful of the effect that humans have on the natural and historical resources of the park.

“We’re proud to have such natural diversity in the park while still allowing a great number of visitors. Over one million people come to the Great Falls section of the park each year -- runners, hikers, bikers, climbers, kayakers, fisherman, and many other folks.”

He added, “Yet this enthusiastic appreciation for the beauty of Potomac Gorge could threaten to destabilize some of its most sensitive species. In some cases we are in danger of loving this area too much.”

BESIDES RECREATIONAL overuse, threats to the biodiversity of Potomac Gorge identified in the study include native plants being overrun by foreign plants, pollution and siltation of Potomac River tributaries from neighboring land use and development, and deer overbrowsing of rare and common species alike.

To address these threats to the Gorge’s biodiversity, The Nature Conservancy will work with partner groups to maintain forest buffers, promote water conservation, and teach landowners about landscaping with native species in the Gorge. The National Park Service and The Nature Conservancy will continue to track the ecological health of Potomac Gorge to fill gaps in knowledge.

The Nature Conservancy of Maryland/D.C. and its 30,000 members have helped protect more than 50,000 acres in the state, using outright purchase, conservation easements, and voluntary management agreements with landowners. Visit the Nature Conservancy at www.nature.org/marylanddc