The Mother Lode
The tropics are renowned bastions of biodiversity. But scientists are finding that our own backyard rivals the rainforests as they uncover dozens of new species each year in Great Smoky Mountains National Park.
With his tall, barrel-chested frame, thick beard, and handlebar mustache, Keith Langdon looks the prototypical national park ranger. Sitting in his office in the Twin Creeks Natural Resources Center, the Great Smoky biologist and ATBI point person sifts through slides of some of the park's unique, and often unseen, fauna. The Twin Creeks area, which draws its name from LeConte Creek and Scratch Britches Branch, is one of the most biologically diverse sites within the park, he explains. "It's sort of a surprise, because it's second-growth forest. Portions of it used to be cornfields."
You can thank the park's 100 native tree species, many of which have reclaimed the former cropland since the park was established in 1934, for contributing substantially to the richness. High overhead the forest's canopy--knit together by eastern hemlocks, beech, red oak, basswood, hickory, and other softwood and hardwood species--blots the sun and holds within the forest moisture that evaporates from the cascading creeks or transpires from the thick vegetative blanket. And there's a lot of moisture to be captured. On average, seven feet of rain and snow falls here each year. Along with stoking the park's waterways, this moisture nourishes everything from more than 200 bird species to hellbenders, a curious, oversized member of the salamander family, to slime molds, often-microscopic growths that "bloom" after rainy weather.
Fungus-like although not true fungi, slime molds can be found in moist vegetated settings, where they eat bacteria that engineer decay, helping nutrients cycle through the ecosystem. Usually hard to see with the unaided eye because they're Lilliputian, under a microscope these molds appear like miniature forests in hues of green, black, coral, red, yellow, or gold. They disperse through their wind-borne spores. During the "fruiting" process that produces the spores, when slime molds "sprout" to visible sizes, they can be positively breathtaking. You often have to search for these life-forms in the forest duff--flip a rotting log, check the cracks in a well-aged tree stump, rummage through a pile of last fall's leaves--though sometimes they erupt on a pine bough in such large numbers that they appear as a blob.
"Some of them produce what I would say are some of the most beautiful, intricate, miniature works of art that you can find in nature," says Steve Stephenson, an ecologist at the University of Arkansas who has devoted himself to studying slime molds in the park since 1982. "They're truly microscopic organisms, but when they form a fruiting structure you can actually see it without the aid of a microscope. They could be a couple of millimeters tall," he says, "but the rest of the life cycle, you could walk through a patch of forest and never know they're there."
So productive are the Smokies' forests for slime molds that of the estimated 850 to 900 species known worldwide, about a quarter reside within the park. But so what? What's the point of a microorganism some refer to as "dog vomit"? "Anywhere there are plants, you're going to find slime molds," Stephenson explains. "A healthy soil has lots of microorganisms in it. You take them away and the soil is not nearly as healthy." That, in turn, can have a ripple effect on the balance of the larger ecosystem. Scientists are also looking into how slime molds might benefit human health. In laboratory settings the organisms have been used in National Institutes of Health-funded Alzheimer's disease research, cancer studies, and developmental research, says Stephenson.
The researchers' findings beg the question: Does the biodiversity spring from the sizable and sprawling ecosystem that cups the park, or is it there because the park has protected these habitats from the pressures of development?
"There's certainly a great diversity of habitat there. You've got the elevational gradients, and then the heavy forests, the big open meadows. So the diversity is part of it. Management of the park is part of it," answers Steck. "One thing that is a little bit curious is that some of these flies were thought to be very rare, and we find them abundantly in the park. [But] outside the park we've had trouble finding them."
It could be, he says, that the effort to tally species outside the park doesn't nearly match the effort inside. Or perhaps it's the bias of their collecting. Or it could be that development and agricultural chemicals outside Great Smoky leave the park as a sort of refuge.
If Great Smoky Mountains National Park is indeed an ecological ark, then the Twin Creeks Natural Resources Center might be considered its hold. When I return there park ranger Langdon guides me through curatorial rooms where tens of thousands of species of moths, butterflies, beetles, bees, plants, snakes, salamanders, fish--even a mounted passenger pigeon--are stored. Finally, we enter a workroom where a map of the park is tacked to one wall. Glancing at the map, Langdon says he looks forward to the day when, thanks to the ATBI, he'll essentially be able to throw a dart at it and tell you what life can be found where it lands. But he also hopes that America realizes before it's too late that riches await them across the nation. "This diversity is found in a lot of different places," he tells me. "We can't predict where it's found. The country needs to get to work."