Paradise Paved: Chatham adding almost 3 acres of built surfaces per day

By Mary Landers
The Savannah Morning News
March 11, 2007

Chatham gains almost 3 acres of built surfaces a day as green space shrinks steadily. Southern Belle that it is, Savannah might not like the time-lapse images researcher Liz Kramer makes.

In them, the view of the metropolitan area since 1991 grows paler as the tree canopy fades away. Blotches of paved and built-over surfaces increase during the same period.

Using satellite data, Kramer , who directs the Natural Resources Spatial Analysis Laboratory at the University of Georgia's Institute of Ecology, has created similar time-series maps for counties all over Georgia [8]. They tell her that the Savannah area is tied for sixth place among Georgia counties with the most rapidly changing land cover.

In fact, Chatham County has gained almost three acres per day of paved or built-over surface while losing 28 acres of tree canopy per day from 2001 to 2005. That translates into a cumulative loss of 41,327 acres of tree canopy and a gain of 3,802 acres of impervious surface.

The numbers alarm Paul Wolff, a Tybee Island City Council member who is greener than Savannah on St. Patrick's Day.

"That's terrifying," he said. "When you hear numbers like that, it's in Brazil or far from home. And we're replacing it with concrete and rooftops."

Concrete consequences

The bird's-eye view of the landscape helps many to acknowledge what they already know at some level, Kramer said.

"It's happening all around. I don't think people understand the cumulative effects of land-use decisions," she said. "We haven't recognized what that tree loss looks like."

The effects are far-reaching, said David Kyler, executive director of the Center for a Sustainable Coast.

More impervious surfaces - such as roads, buildings and parking lots - mean less rain soaking into the ground. That leads to more runoff carrying more pollutants to streams. It also contributes to more flooding.

And then there are energy issues.

"You also have increased heat buildup, a heat island," Kyler said. "That means more energy use."

A greater demand for electricity further strains waterways because power plants use water for cooling, losing some to evaporation and thermally polluting waterways.

Kyler is especially concerned that the rate at which coastal Georgia is getting paved over is outstripping its already robust rate of population growth.

"We are suffering a high rate of population growth, yet we have double that rate of increase in pavement," he said. "We all have bigger homes, bigger lots, bigger driveways. It's the gated community, big starter castle mentality. People have more dollars than sense."

The value of trees and unpaved surfaces is one of avoided costs, said Jeffrey Dorfman, professor of economics and co-director of the Land Use Studies Initiative at the University of Georgia.

"More trees and unpaved surfaces soak up more water naturally, leaving less money spent on stormwater systems," he said. "They save you from having to spend money. You can't spot it, but if it weren't there you'd spot your taxes going up."

Canopy comeback

Researchers who analyze growth patterns have a saying: "The last crop is blacktop." That means built areas rarely revert to their natural state. But canopy loss isn't so set in stone - a point Krameris the first to reiterate.

In fact, tree cover went up in Chatham County from 27 percent in 1991 to 33 percent in 2001. It was the subsequent building boom, much of it on former pine plantations in west Chatham, that slashed the canopy after that.

"There were a lot of clear cuts on the border of the county as land moved out of forestry, like at that Pooler site," Kramer said. "Some of that canopy is going to grow back."

Regrowth is part of why Kramer's canopy numbers don't worry Gordon Denney, Savannah’s landscape architect. The city's tree ordinance is designed to give Savannah a 50 percent canopy cover, a baseline derived from studies conducted in the 1980s, Denney said.

Savannah already is at a point at which it is replacing more trees than it removes. It just takes a while for those trees to grow their mature canopy.

Denney points to a historical example."Look back at old photos of Victory Drive, and all you see are large palms, no street canopy," he said. "A hundred years later, it's a canopy-lined street that's just amazing."

It can take decades for a large hardwood to provide maximum shade, but it will happen, he said.

At least it will in Savannah and unincorporated Chatham County, where the tree ordinances are strong.

Tree advocates such as Dale Thorpe of the Savannah Tree Foundation [36] have more concerns about Chatham's other municipalities, some of which have only token ordinances and lack enforcement. The Savannah Tree Foundation operates county-wide and is putting a greater emphasis on those municipalities.

"We are trying to move westward and did just have a planting in Port Wentworth," she said.

The Georgia Forestry Commission is targeting those same communities.

Forester Daniel Westcot has set his sights on Pooler.

"Pooler has a tree ordinance, but it's noneffective," he said. "It doesn't require much as far as planting trees back or protecting trees."

Those items are essential to keeping the Savannah metropolitan area well covered in green, Thorpe said.

Still, Kramer's numbers - the 28 acres a day of canopy loss - give Thorpe pause, even as she enjoys Savannah's tree-lined streets daily.

"I think we're under attack and need to get smart," she said. "I'm a little floored, like: 'Oh dear, we really need to renew our efforts.' Maybe we've been fat and happy."
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