Massive fires that ravaged Indonesia’s vast tropical rain forests over thelast decade are remaking one of the richest biological landscapes on the planet.
The fires have reshaped the habitat on much of Borneo, the world’sthird-largest island — changing factors from the height of the forest canopy towater levels in the rivers and humidity in the air. That, in turn, is affectingwhich animals rebound and which ones peter out.
Among those species that appear to be thriving despite ongoing threats aredozens of species of bats that nest in the cave systems on the southern part ofthe island, an area known as Kalimantan, and feed on insects in the forest atnight. But other small mammals, along with a multitude of bird and plantspecies, have yet to recover from massive destruction caused by the 1997-98fires, considered the largest in recorded history.
When fire occurs, “the generalists survive,” said Leo Salas, aVenezuelan biologist working here with the Nature Conservancy, aWashington-based environmental group. “The specialists don’t.”
The cave-dwelling bats are prospering in and around many of the new”secondary” forests that have regrown even in areas that burned two orthree times, based on early results from a month-long biological survey by theConservancy of sites on the Sangkulirang Peninsula. Many of them are flexibleabout where to roost, and they eat a variety of mosquito-size insects.
“I’ve taken more species [of bats] in this project then I haveever,” said Matt Struebig, a conservation biologist at the University ofLondon, who has been collecting and categorizing bats in Southeast Asia’sbiological hot spots for three years. Last summer, Struebig found 22 species atone site alone during a week of trapping, capturing several species notpreviously known to exist in the area.
Struebig thinks that caves protected certain species of bats from the fires,even as species that live in the forest declined.
“These are among the most biologically active caves I’ve everseen,” said Cyndie Walck, a geomorphologist with the California State ParksSystem.
Other scientists taking part in the biological survey in harder-hit areas hadless encouraging findings.
The effects of the fires on some insect species, according to LouisDeharveng, a French biologist with the Museum of Natural History in Paris, were”devastating.”
Luckily for the bats, the high and inaccessible limestone caves that dot thelandscape here often are out of reach of loggers.
The porous, cave-pocked limestone cliffs — a kind of terrain known as akarst system — formed from coral reefs that lay under the sea 2 million to 3million years ago. The reefs were compressed into limestone through continentaldrift, and now appear as jagged white rock formations puncturing the flat, greenlandscape. Over time, water has picked up carbon from the soil, eventuallyforming calcium carbonate, which slowly dissolves the rock to carve out cavesand sinkholes.
“Karst areas are often last refuges for fauna,” said JaapVermuelen, a Dutch scientist who works at the botanical garden in Singapore.”All the surrounding lands are heavily used [and] logged. But limestonecaves, because of their inaccessibility — they’re still there.”
Some of the biggest caves are far from any village and can be reached only bya long riverboat ride and a treacherous hike through dense forest. They areideal for a number of species that have adapted themselves to live in the darkenvironment with constant humidity of as much as 100 percent.
Snails favor the karst and absorb some of its calcium to strengthen theirshells. Small beetles and cockroaches feed on the thick layer of guano depositedin the caves by bats and in turn serve as food for other predators.
Scientists have yet to identify a new fish found in shallow pools in a cavecalled Sungai with a tall, vaulted ceiling. The fish, which looks like a smallcatfish with clear skin, did not respond to flashlights and appeared to beblind.
Many species inhabiting the cool, dark caves have evolved deadly poisons toensure that they catch their prey, the surveyors said.
“It’s a straightforward carnivore system,” Salas said. “Someof the most spectacularly horrendous insects live in caves.”
Because of its inaccessibility, “most of this area isn’t hotlycontested,” said Scott Stanley, the Conservancy’s program manager for EastKalimantan. Still, the Indonesian government has authorized large loggingconcessions around the karst areas and failed to curb widespread illegallogging.
Conservationists say the logging, in addition to directly destroying habitatfor many species, increases the risk of fires that compound the ecologicaldamage. Once giant hardwood trees that top the canopy in lowland forests are cutdown, the entire ecosystem changes, becoming less humid and more susceptible tofire.
The Conservancy is hoping to use evidence of the rich biological diversityhere to encourage the government to develop and enforce a conservation plan.
Despite the effects of logging and fire, the remaining patches of old-growthrain forest outside the caves still house one of the most diverse arrays ofspecies anywhere. Visiting researchers and several Indonesian scientists whojoined the expedition have located dozens of insects that have never beencatalogued.
“These are the animals that nobody’s interested in,” Vermuelensaid. “But they make up the largest number of species in the world. Eightypercent have no name. Nobody’s ever seen the things.”
Scientists are concerned, however, that they have not found certain”indicator species” here. This could be a sign that the fires havepermanently damaged the health of the fragile ecosystem. At one site along theemerald waters of the Marang River, the fires — which flared again in 2002 insome areas — destroyed the softwood trees favored by woodpeckers.
“Here, the only trees that are standing are those that have very hardwoods,” said Mas Noerdjito, an Indonesian biologist who studies birds atthe government’s national research facility. “There is only one species ofwoodpecker here.” Also mostly absent were large dying trees whose hollowtrunks provide nesting areas for some bird and bat species.
Nor were there many rats or squirrels — which serve as”architects” by spreading seeds around the forest.
Environmentalists fear that one of the world’s largest tropical rain forests,surpassed only by those in the Amazon and the Congo, is in great peril — alongwith the array of plant and animal life it supports.
“This is probably getting hit the hardest in the world,” Stanleysaid.