A CAPITAL CRISIS.

This spring tourists will flock to Washington, DC's Tidal Basin for the ritual viewing of its famous cherry blossoms. But few will guess the nation's capital is an urban forest in crisis.

Recent studies paint a sobering picture. AMERICAN FORESTS' regional ecosystem analysis of the District of Columbia reveals average tree canopy cover throughout the city's neighborhoods declined from 37 percent in 1973 to 21 percent in 1997. And the most ecologically valuable areas with heavy tree cover (defined as 50 percent or more) declined by 64 percent. The analysis recommends conserving and increasing the city's remaining tree cover as a cost-effective way to capitalize on the economic value of this natural resource.

For years city street trees have fallen victim to the District's financial woes, according to a report from The Committee of 100 on the Federal City. Of 116,000 possible tree locations, about 30,000 are either empty or contain dying trees. The District continues to lose between 4,000 and 5,000 trees each year. The report calls for an emergency program to plant 30,000 new trees over the next three years.

At a press conference in Walter Pierce Park in Northwest Washington, AMERICAN FORESTS and The Committee of 100 presented their findings to Mayor Anthony Williams. The mayor promised to enhance the District's tree program by planting 6,000 trees in Fiscal Year 2000, upping the number of horticulturists on the city payroll from two to three, updating the District's tree inventory, and increasing contracts for priming and dead tree removal.

"Our trees are an important resource to this city, and I agree that we must make all necessary steps to preserve them," said Williams. "Trees not only represent a healthy landscape in our city, but they also have an enormous economic value."

Enormous value indeed. AMERICAN FORESTS' analysis used satellite images and GIS technology, including CITYgreen software, to measure the change in tree cover and to calculate the value of trees. The trees that disappeared in 24 years had performed ecological services worth more than a quarter-billion dollars.

As natural tree cover declined, highly developed areas with less than 20 percent tree cover jumped from 51 percent to nearly 72 percent. This loss of tree cover and increase in impervious surfaces, such as roads and buildings, increased the impacts of stormwater runoff. Stormwater flow during a model peak storm event increased by an estimated 34 percent. Replacing this lost stormwater retention capacity with reservoirs, sand filters, and other engineered systems would cost $226 million. This service was provided previously by trees, vegetation, and natural soils, which slow stormwater movement, lower total runoff volume, reduce flooding, and improve water quality.

Air quality also declined. The lost tree canopy had been removing about 354,000 pounds of pollutants from the atmosphere annually at a value of approximately $996,000. The District's urban forest improves air quality by removing nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, and particulate matter.

"We measure tree cover using satellite imagery because trees provide a good measure of the ecological health of a community," says Gary Moll, vice president of AMERICAN FORESTS' Urban Forest Center. "Washington is like other cities we've studied that are losing their urban forests at an alarming rate. This national trend can be reversed if people realize the value of our cities' green infrastructure. Planting and caring for trees and forests will save money and make our communities greener, healthier, and more livable."

Data for the DC analysis came from AMERICAN FORESTS' larger regional ecosystem analysis of the southeastern Chesapeake Bay watershed (see "Lifeline for a Landscape," Spring 1999). Unfortunately, the District's 16 percent net loss in average tree cover is even greater than the 12 percent net loss experienced during the same period by the region as a whole.

Unlike many suburban areas, the cause of the District's tree loss probably isn't sprawl. Moll says it's more likely that trees planted 50 years ago slowly succumbed to pollution, construction, and other stresses of city life. And more often than not, they haven't been replanted.

"Trees are dying all over the city, particularly in the commercial districts and along the major roadways," says Sarah Boasberg of The Committee of 100. "Partly it's poor maintenance, partly it's a lot of chemicals."

AMERICAN FORESTS recommends cities have an average tree canopy coverage of 40 percent to ensure ecological, economic, and social sustainability. It's all part of AMERICAN FORESTS' five-point plan to battle sprawl and help communities make better, more informed decisions. Armed with data, local leaders, such as Williams, may take this advice to heart.

"If we can't take care of our trees, how are we going to take care of our schools? How are we going to take care of our roads?" Williams said. "Trees are a metaphor of public space. That's what we're fighting for--vital, robust public spaces."