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Bob Ford is crouching over a pothole on Klingle Road NW. This is not one of your harmless, six-inch potholes, not one of your “call Marion Barry and city crews will patch this baby in 20 minutes” potholes. Oh, no—this is a pothole’s pothole. It’s eight feet long from stem to stern, two feet deep, and filled with enough rainwater to bathe your toddler.

But Ford, the natural resources manager of Rock Creek Park, isn’t worrying about busted axles or disintegrating infrastructure. He’s watching mosquito larvae. “Look at them. See them do that little contraction,” Ford says, staring at thousands of tiny worms squirming in the water. “There are probably a dozen species in there.” Insects and plants own this road. Croton bugs leap across the little pond’s surface, which quivers beneath them. Ants trot along the miniature shoreline. Ford swivels on his heels and runs his finger along some asphalt cracks: Emerald-colored moss has grabbed hold of one crack; a wild mint plant has staked its claim next door; a foot-high tuft of grass is anchored in another crevice, its roots slowly chewing the asphalt.

Until five years ago, Klingle Road was an unremarkable street: It carried commuter traffic up from Rock Creek Park, through the steep, twisty Klingle Valley, toward Reno Road and Wisconsin Avenue. Then, in 1990, the District government hauled in some concrete barriers and closed a three-quarter-mile stretch of the road to traffic. Heavy rains had sent torrents rushing down Klingle, shredding the asphalt. City officials were sick of paying to repair it.

When the road closed, the usual neighborhood battle ensued. D.C. bureaucrats periodically announced plans to reopen Klingle. Nearby residents protested with equal regularity, waxing poetic about their quiet new glade, their safe jogging path. Meetings were held. Petitions were signed. Traffic studies were conducted. Local notables—the Washington Post‘s Mary McGrory, Meet the Press‘ Tim Russert—raised their voices in praise of the bucolic retreat. And finally, at the beginning of 1995, the city relented, promising to close the road permanently.

In a 1936 poem, Stephen Vincent Benét fantasized about a hot, wet summer when nature takes Manhattan. Weeds and wild grasses poke through cement sidewalks and stone buildings. Bird-sown flowers root themselves on balconies. The termites learn to eat steel.

Benét titled the poem “Metropolitan Nightmare,” but what is occurring on Klingle Road is more like a dream than a nightmare. Thanks to a half-decade of neglect, the road is undergoing an ecological succession, transforming from concrete jungle to verdant forest. Untouched by traffic, abandoned by road crews, liberated from exhaust fumes, Klingle is becoming a strange and lovely monument to urban decay, Mother Nature’s scornful response to D.C.’s formal gardens and the chemically doctored, manicured Mall.

Ford meets me at the base of Klingle Valley—the knot of road where Klingle Road and Porter Street intersect—on a sunny Wednesday morning. His parent agency, the National Park Service (NPS), owns most of the land around the road, and Ford and his colleagues keep an eye on the flora and fauna of Klingle Valley. Ford has managed Rock Creek Park’s natural resources for almost 20 years. In his olive-and-slate uniform, he resembles an earthbound John Glenn.

It’s 8:30 a.m., but the charcoal-gray asphalt is already baking in the sun. We sidle around the concrete barrier and enter the forest primeval. The thick green canopy shades us, dropping the temperature 10 degrees. The ozone haze from Porter Street traffic recedes, replaced by the dank, pungent odor of decomposing vegetation.

The road deteriorates immediately above the barrier.Leaves,pollenfronds,gravel,> seeds, and sand are matted> down in an organic carpet. Pancakes of as phalting waters have ripped them out and swept them toward the bottom of the hill. I step on a chunk. It crumbles like a clod of dirt. I turn another chunk over, exposing a community of irritated worms and jumpy insects.

We spot a mourning dove a few feet ahead. The brown, shy bird—a kind of well-mannered pigeon—is pecking tranquilly at the seeds piled on the road. “A lot of birds will find a surface like this very attractive. It’s like a big dinner plate,” Ford says. “Instead of having to peck through the forest, they just come out here and eat the seeds or worms or insects right here on the road.” The dove skitters away, perhaps surprised by the human presence.

A little further up the hill, we encounter an ailanthus—the “tree of heaven.” It’s about eight feet high and it has grown through the asphalt on the narrow shoulder. “That’s the tree from A Tree Grows in Brooklyn,” Ford says with a grin. “The tree of heaven will grow anywhere. A seed probably fell in that crack. It’ll grow in even marginal soils and spread the asphalt.”

Ford halts by a gigantic tangle of leaves. It’s poison ivy, but on a Brobdingnagian scale. If this were a path or a trafficked road, a ranger would trim it. Instead, the creeping mass has swallowed a large fence post and is now crawling—tendril by leafy tendril—across the road. Ford kicks a leaf with his boot-toe. “This is quite a good plant,” he says contentedly. “It provides food for 53 kinds of bird.”

It’s not just poison ivy that’s running rampant. Everywhere we turn, vines and trees—unchecked by government clippers—are retaking the abandoned road. “If we waited long enough, waited a couple of decades, this vegetation would just cover the road completely,” the naturalist says.

Ford pokes at a Virginia creeper inching along the asphalt. He shows me a wild raspberry shoot, a wild grape vine, a colony of papaw. We wade through a forest of jewel weed, which has sprung up in a sunny spot: This succulent soothes poison ivy rash. Ford warily eyes a devil’s walking stick—itsthorny branches probably snag dozens of unwary walkers. The trees, also untrimmed by human shears, are growing together in a low arboreal arch. Branches from white oaks and red oaks, mulberries and box elder maples dangle above the road. They’d scrape the paint off any passing car’s roof. (Not that any car could navigate Klingle: An enormous black walnut has toppled across the road, blocking passage.)

A spice bush is peeking through the asphalt. Ford gently pulls off a leaf. It smells fragrant and peppery. “It’s a terrific food for thrushes,” he says. A princess tree perches precariously above Klingle Run, the stream beside the road. Its roots are lifting andbuckling the road. The princess tree’s wood is so precious that poachers heist mature specimens from Rock Creek Park. When this tree grows a few feet, it too could be stolen.

Until now, Ford has been a genial guide. But then he spies a porcelain berry, and his face darkens. Like America itself, the park service is struggling over the issue of immigration. Unwanted travelers from Asia and Europe—porcelain berry, kudzu, English ivy, Asian bittersweet, pachysandra, and more than 30 other alien species—are encroaching on our native American flora. These “exotics”—Ford almost spits the word—have no natural enemies. They grow riotously in Rock Creek Park, overwhelming endemic species.

“Look at this porcelain berry!” Ford exclaims, grabbing and angrily shaking its sinuous branch. “It’s taking over this tree.

“And look at this English ivy. It’s all over creation,” he continues, waving his hand at the dark green plant that is beginning to carpet the north side of the road. “How can our wildflowers, our fawn lilies and bluebells, compete with that ivy?” Ford asks, sounding rather like Pat Buchanan. (Ford and his colleagues practice their own version of Proposition 187 in Rock Creek Park: NPS tears out kudzu colonies and flames English ivy with kerosene torches.)

But Ford relaxes a minute later when a pair of squirrels stroll out of the woods to forage on the road. Squirrels are the most visible mammal in the Klingle Valley. They exhibit a calmness unknown among their downtown relatives. The Klingle squirrels bask on the road, lazily collecting breakfast from among the fallen seeds and leaves. They are certain that no nasty Pontiac is going to zoom around the curve and smush them. Chipmunks, opossums, raccoons, and red foxes also make their homes along the road, Ford says. Klingle Run won’t sustain a beaver dam, he adds, but sometimes “a juvenile beaver who doesn’t know better” tries to dam it anyway.

Two bright-red cardinals are jawing on the road as we approach the concrete barriers at the top of Klingle at Cortland Place, “They’re males—the females are brownish—and they’re squabbling over territory,” Ford says. “Look at them posturing and preening.”

Ford raises his hand to silence me and starts picking out bird calls from the valley’s avian cacophony. He quickly notes a catbird, a pileated woodpecker, a flycatcher.

“That’s the Carolina wren, the tea kettle bird,” he chirps, “Tea kettle! Tea kettle!”

Ford pauses. A dragonfly buzzes by. It circles us suspiciously for a few seconds, then flies away to divebomb a pothole pond.