email a friend iconprinter friendly iconStone Forest
Page [ 5 ] of 7

But it is in the humid grike bottoms, where water and soil collect, that the environment is richest. Here, among arrays of orchids and enormous tropical hardwoods, roams a bestiary: giant snails and fist-size, cricket-like insects, large chameleons, emerald green snakes, and red rats. The lemur-eating fossa—a wiry, thin-coated mammal with retractable claws that resembles something like a large cat—also patrols the tsingy. Finally, below the soil and the mud are caves and tunnel passages, the subway system where fish, crabs, insects, and other creatures live and commute, some without ever surfacing.

This walled city has sheltered its residents even as Madagascar's other ecosystems disintegrated. Scientists call it the perfect refuge.

The concept of "refuge" in biology signifies a safe zone, like a refugee camp, to which living things withdraw as their habitat shrinks. Once they become cloistered in refuges, animals and plants often become increasingly distinct from even their close relatives. Madagascar itself epitomizes this process, so unusual and removed are many of its species from their cousins on the African continent. Lemurs are the island's best known creatures. Their precursors once inhabited Africa but eventually went extinct there, leaving the continent to other primates, and today lemurs are found only in Madagascar. Free from the competition that likely drove them to extinction elsewhere, they evolved into richly varied forms, including now vanished species that were big as gorillas and the palm-size mouse lemur, the smallest living primate.

The tsingy also provides refuge on a smaller scale. Protected by walls of stone and wet by seasonal rains, the forest within is very different from the palm savanna curling around it to the east and the coastal areas that flank it to the west. It is a relict of another era, when forest corridors might have linked one side of the island with the other.

In recent millennia a natural drying trend fractured those corridors. Then came people. Since the first humans arrived in Madagascar some 2,300 years ago, nearly 90 percent of the island's original habitat has been destroyed, most of it harvested for timber or felled or burned to create room for crops and, more recently, cattle. As a result, many of the species that lived on the island are thought to have gone extinct.

Page [ 5 ] of 7