I was unsure if the scene was a comedy or tragedy, but there was no doubt about its irony.

Consider it: Where once stood about 35 of the oldest, broadest-branched trees in a District of Columbia neighborhood that already had too few, a gang of men and bulldozers cut them all down and piled them all up in an afternoon.

The kicker came as the workers in hard hats strung vinyl sheeting around the fencing erected to keep neighbors out of what was once their dog park. That vinyl sheeting was covered with airbrushed pictures of trees in all shapes and sizes, a perfect facsimile of the natural canopy, eerily reminiscent of the just-ruined scene of tranquility.

Outraged neighbors, long in opposition to what was causing this scene—a hotel’s plans to expand—had spray-painted messages of protest on the sidewalk. Apparently involving their children in fledgling acts of civil disobedience, their graffiti called out, “Not My Childhood” and “Not My Park.” Their pleas fell on deaf ears, mine included.

I found myself wishing that I had joined their fight earlier, thinking that perhaps we should all closely read between this sidewalk’s lines. For when trees go, so do neighborhoods. Any kid who has climbed one can tell you that. At the same time, our communities lose biological functionality that can be measured in dollars and cents.

Urban tree canopy intercepts rainwater, allowing it to be absorbed and naturally filtered, reducing the amount that races through streets and into gutters as runoff. This limits the amount of pollutants that are flushed off road surfaces and sidewalks, while stabilizing sediments that can choke aquatic populations. Fish and wildlife receive an additional boost from trees cooling streams and providing shelter for birds.

The benefits of an intact tree canopy become clearer with an examination of New York City, which is one of very few cities exempted from using expensive filtration equipment on its water supplies because it draws from three forested watersheds sitting between 25 and 125 miles from Manhattan. These intact watersheds deliver remarkable purity to more than 10 million people: At taste tests, New York City’s tap water has been named one of the best in the world.

The benefits of tree canopy are readily seen in the Chesapeake Bay watershed as well. An analysis by the nonprofit group American Forests estimated that Leesburg—located in a rapidly developing section of Northern Virginia—lost 71 percent of its urban tree canopy between 1992 and 2001. With it, the city lost stormwater management and air pollution reduction services valued at nearly $9 million. More irony: The city recently approved an expenditure of about $8 million for flood control projects.

Urban tree canopy also improves the human condition. A new report, “The State of Chesapeake Forests,” produced by the U.S. Forest Service and The Conservation Fund, a national nonprofit organization, revealed that urban tree canopy absorbed more than 500 metric tons of air pollution in Baltimore and nearly 400 metric tons in the District of Columbia in a single year.

Considering the effects of air pollution on human health, with known harms ranging from early childhood asthma to adult lung cancer, the importance of a healthy tree cover should rapidly ascend society’s ladder of priorities. And when energy concerns are taken into account, urban trees take on even more importance.

The State of the Chesapeake Forests report explains that trees commonly lead to energy savings: cooling buildings in summer and warming them in winter. According to the report, homes with shade often have energy costs that are 20–25 percent lower than those without.

Another study found that one mature tree can provide the equivalent of five, 10,000 BTU air conditioners running for 20 hours per day. And still another study, this one by the U.S. Department of Energy, found that a nationwide shade program could reduce air conditioning use by at least 10 percent.

Realities such as these should lead to a societal shift toward improved urban tree conservation.

Fortunately, some cities in the Chesapeake Bay watershed such as Annapolis, Baltimore, Leesburg and Columbia, PA, have signed up to become partners in a state-federal program to aggressively pursue urban canopy enhancement goals.

Unfortunately, the total number of cities to have joined this program is seven, when the number of cities supposed to enroll, as put forth in a 2003 directive signed by the governors of Maryland, Virginia and Pennsylvania, is 15.

This inertia is unacceptable. We must not stand idly by, as I did when the first signs of trouble took root in my neighborhood. Take my word for it, with such action, or rather, inaction, only comes regret. Instead, we must immediately plan to protect the urban tree resource we already have—and plant to enhance the resource for the future.