Wetlands study finds drawback to light development Diversity of species not being encouraged by urban green space


PAWLING, N.Y. - Scott Silver, a biologist fresh from studying howler monkeys in the rain forests of Belize, stalked new quarry in the neatly mowed back yard of a town- house complex 70 miles north of New York City.

From the lawn, he peered into an adjoining watery patch of cattails, red maples and wildflowers that is an arm of the Great Swamp, one of the largest wetlands in New York state. Then, waving a butterfly net, he sprinted past a startled resident on a nearby deck, but his target eluded him, fluttering over the townhouse roof.

Silver is part of a research team studying life on the interface between suburbia and wilderness, a troubled zone where turtles, fish, butterflies and other wild creatures are steadily retreating before an ever-expanding sprawl of housing, office parks and shopping centers.

Their goal is to find which kinds of human uses of the land mesh best with the needs of the slimy, winged or scaly inhabitants of the 4,800-acre swamp and the surrounding watershed, which encompasses more than 50,000 acres of rapidly developing hills and valley bottoms along a busy commuting corridor in eastern Putnam and Dutchess counties.

Early findings

Early findings from the study, which began this summer, appear to be upending conventional wisdom, said Dr. Michael W. Klemens, the director of the project and a reptile and amphibian expert at the Wildlife Conservation Society, which is based at the Bronx Zoo.

While zoning and suburban planners favor light development over large areas to preserve green space, these areas actually appear to lose as many species as more densely populated spots, like the heart of a village, he said.

As the variety of animal life declines, large populations of a few "weedy species" dominate, he said. Lost is the variety that indicates a rich, healthy ecosystem.

And because the effect is spread out, instead of focused in a village center, the impact on the overall vitality of a unique area like the Great Swamp can be substantial, he said.

In general, the findings tend to favor the idea of focusing development in traditional villages surrounded by larger areas of land that are left largely untouched, he said.

In the past, most attention from environmental groups has focused on highly visible species like eagles, he said, but a decline in lowly forms like salamanders can prove more significant. In some northern forests, he said, there are more pounds of red-backed salamanders per acre than any other species - deer, birds and the rest.

Base of ecosystem

"These are not inconsequential creatures," Klemens said. "They are the base of our ecosystem. Removing species from an ecosystem is like removing a few cans from a supermarket shelf," he explained. The stacks of cans become unstable. "Sooner or later, the whole thing collapses."

The initial findings have come from a long-term survey of reptiles, amphibians, dragonflies, butterflies and fish in three areas that represent the range of conditions in the region.

One tract of bogs and wooded hills in the town of Dover Plains has seen little human activity for decades; a second area in Patterson includes some wild swampy land but also pastures and some buildings; and the third study area is the village of Pawling itself, which ranges from a quaint downtown to townhouse complexes and stream-laced farmland.

After years of field work in Tanzania, Klemens decided several years ago to shift his focus to the endangered ecosystems close to his Westchester home. And what he found startled the conservation community.

Westchester, which on the surface appears to have retained large areas of greenery despite decades of intensive development, has actually become biologically impoverished, he said.

In 30 years, the county has lost 30 percent of its species of reptiles and amphibians, he said, largely because the landscape has been fragmented by roads, drainage ditches, lawns and parking lots, which are "killing fields" for small woodland animals.

The intersection of suburbia and untrammeled nature moved north into Dutchess County, where growth was accelerating.

Klemens began doing field work in the Great Swamp in 1994, after a local resident sought him out at a lecture and urged him to help her prevent Westchester-style development from spreading uncontrolled.

'Electrofisher' at work

Surveying on this day started with an expedition to a stream running under a trestle along the Harlem line of the Metro-North Commuter Railroad. Silver donned waders and a $6,000 backpack-mounted "electrofisher," a battery-powered device that stuns fish, crayfish and frogs with an electrified wand.

In pools barely larger than a bathtub, Diane Murphy waited for the electrical current to be turned off, then plunged her hands into the water and retrieved an assortment of pickerel, sunfish, shiners, bass and frogs, plopping them into a bucket.

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