Vegetation reclaiming New Orleans

USA Today:

It's not the mists of time that lay claim to abandoned cities. It's the undergrowth.

Fast-spreading vines and other weeds are among the first tentacles Mother Nature sends up to grip a deserted city. So it was that Troy, Chichen Itza, Angkor and other metropolises of antiquity vanished and were forgotten. Other classical cities, including Rome, once became partially lost to greenery and decay.

Now, in hurricane-ravaged and largely abandoned parts of New Orleans, the timeless process is being replayed. In swathes of the once-submerged Lower Ninth Ward, for example, houses, trailers and sidewalks lie neglected and disappearing. The weeds appear to be taking over.

The rapidity of nature's resurgence in the fertile Crescent City is no surprise to scientists. "We've got exuberant vegetation down here in Louisiana," says Steven Darwin, a botanist at the city's Tulane University. Before Hurricane Katrina in August 2005 and the attending floods, he says, "people were mowing their lawns, keeping this vegetation under control."

But since then, plenty of spots have gone to seed. "My neighbors haven't been back for two years," says Darwin, whose uptown neighborhood, Carrollton, didn't get flooded. "You should see their backyard. It's almost impenetrable."

Mike Davis, 19, echoed that sentiment as he surveyed the yard where he grew up on Tonti Street in the Lower Ninth. He and his brother Jason, 18, still have relatives in the neighborhood but have resettled across the Mississippi in Harvey, La. During a return visit, the two sat on the hood of their car in front of their old home, which lies half -obscured behind trees and weeds. "There's no more house," Mike Davis says. "It's a forest."

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"Cities can be buried extraordinarily quickly," says C. Brian Rose, president of the Archaeological Institute of America. Typically, he explains, a catastrophe — armed conflict, for example, or an earthquake, fire or flood — will first depopulate a city. Then seeds will blow in on the wind, take root and grow, particularly if a flood has deposited a new layer of soil.

Weeds also may sprout from buried roots, which can be surprisingly resistant to floodwaters. And if remaining residents don't put brakes on the process, the city's architecture is doomed. "Roots will grab hold of the foundations and bring down the structures over time, even if they're stone," Rose says. "In time, nothing will be left. All you'll see is foliage."

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Environmentalist have been looking at the wrong enemy. It is not man that is the problem, but vegetation that wants to take over the earth. I became acutely aware of this when I moved to the country and built a house. It is a constant battle to keep the vegetation from trying to reclaim the space around the house, not to mention the acreage around it. I could probably use several full time employees to tame the rampant vegetation. The undergrowth is particularly persistent. I think we need a new environmental movement that will concentrate on the threat of vegetation. Perhaps we can figure away to convert undergrowth to biomass. If so, we would never run short of fuel.