Long ago, the ocean covered all of what is now the U.S. state of Florida - except for a long, sandy ridge stretching down the center of the peninsula. Today this ancient sand dune, called Lake Wales Ridge, is home to one of the largest concentrations of rare plants in America. Endangered birds and animals also live here, but protecting this fossil ecosystem is proving a very difficult task.

Along Lake Wales Ridge, white sugary sand, sometimes as deep as 60 meters, reflects the bright sun. Stunted oaks, cactus, palmetto and thistle form a scraggly landscape with no grass or canopy of trees in sight.

Ecologist Hilary Swain, who grew up in the British Isles, heads Archbold Biological Station, a research center at the south end of the ridge. She says this habitat - known as "scrub" - is a national treasure.

"One of the special things about Lake Wales Ridge was that as Florida sea levels have risen and fallen over previous millennia, the ridge stood above all of this, at least a million years," she explains. "So, like any island system that's been isolated, there are many species here that are found nowhere else on earth."

And that attracts researchers from across the country and around the globe. Jim Carrel, a behavioral biologist from the University of Missouri, is here studying one of those unique species, the Archbold burrowing wolf spider. Carrel says it is found along only about 65 kilometers of the ridge.

"This spider builds a burrow in the sand, and it spends almost its entire life down in the burrow or near its entrance. When an insect approaches, the spider will dart out, attack it and take it back down, but other than that, the spider will be in its burrow for virtually all its life."

Unique, rare creatures make their home on the ridge

More than 40 species of rare plants and animals inhabit the scrub, and scientists are still finding new species here. Mark Deyrup says he enjoys looking for them. The research biologist has been working at Archbold for 25 years.

On a stretch of sandy trail, he points to signs of a very rare reptile.

"This is a track made by an animal called the sand skink. The sand skink is a small subterranean lizard that's virtually legless, and it swims through the sand - or just under the surface of the sand. And as it does so, it pushes up a little ridge of sand that falls down behind it, and it leaves these S-shaped curves."

A threatened plant called the Florida rosemary can be found on the highest, driest piece of scrub. Like other plants living on this very porous sand, the rosemary has adapted to desert-like conditions. Although it's not related to the culinary rosemary, Deyrup says it's quite aromatic.

"It does have a distinctive smell, and the leaves are rolled up. There is a specialized grasshopper that only lives on this plant, and there's also a moth - a pretty, green moth - that is only on this plant, as well."

A race to protect what's left

This ancient ecosystem of Florida scrub once covered 100,000 thousand hectares on a 160-kilometer long stretch of land. Now, says Swain, only a fraction is left.

"Gradually, we lost a lot of that habitat, mostly through conversion to agriculture, citrus development and more increasingly housing development," she says. "So estimates are somewhere between 83 and 85 percent of original habitat has been lost, and somewhere in the range of 15 percent still extant. Approximately half of that is now under some form of protection."

A portion of Lake Wales Ridge has been designated as a national wildlife refuge for rare plants - the first of its kind in America to protect a whole ecosystem of plants. Other parcels of land on the ridge are protected by the state of Florida and The Nature Conservancy organization. But outside this patchwork of preserves, the remaining pieces of scrub are scattered and mostly privately owned.

Swain says that presents a challenge to any government measures to protect them. Nevertheless, she insists, preserving what's left of this ecosystem is well worth the effort.

"There is potentially a treasure-trove of useful chemicals in any ecosystem. Whenever I look over the Florida scrub, one of the things in the back of your mind is, 'What hidden information is out there that we've never yet revealed?'"

Adaptations by scrub plants could help modern agriculture

Deyrup agrees. He says the ridge could provide answers to some important agricultural questions.

"One of the things that scrub teaches us is how to live with very little," he says.

He points out that scrub plants are living in a habitat where crop plants would wither and die.

"They survive year after year, and they do that all by tricks. They all have tricks that allow them to live in a place which is very dry, very bereft of nutrients. And those kinds of tricks, in the future, we may be able to incorporate into our crop systems and save an immense amount of resources, and labor and pollution."

But as Florida's population continues to grow, biologists are racing to find those hidden tricks and treasures in this ancient landscape.