RACE AGAINST TIME
Texas botanist leads project to collect rare plants in Cambodian caves.
KAMPONG TRACH MOUNTAIN, Cambodia — Millions of years ago, a cluster of coral reefs stood firm here as the water receded, leaving them surrounded by the marshy, mangrove-studded Mekong Delta.
Today, these reefs have been carved by the wind and rain into spiky limestone cliffs known as karsts that stand stark against the Cambodian landscape, even as the lowland rain forest around them has been denuded by centuries of intensive rice cultivation and logging.
The karsts are full of nooks and crannies that have nurtured highly specialized plants and animals found nowhere else. They are also important to humans, studded with small altars and temples that are thought to be homes to neak ta, landscape spirits in the local animist pantheon. Soon, they will be gone. A small group of scientists are now racing to document rare plant life in these limestone karsts before local companies quarry them to dust and grind them up for production of the cement that is fueling this country’s building boom.
Most of the wood in mainland Southeast Asia has already been logged to support the region’s rapid economic growth and its relentless appetite for luxury hardwood. (Nearly all the forest cover in neighboring Thailand is gone and Cambodia is now experiencing the fastest acceleration of forest loss in the world, despite a putative ban on logging.) Cement and concrete are also in high demand, so the karsts are next in line.
“They are the last refuges of what made it to the Mekong Delta, natural harbors for a specialized kind of vegetation that has very little timber value, sanctuaries of rare species,” said J. Andrew McDonald, a botany professor at the University of Texas Rio Grande Valley, who is spearheading the plant collection project with support from the International Union for Conservation of Nature.
The limestone habitats can act as “arks” of biodiversity that replenish surrounding areas after ecological damage. But they are so complex that, once destroyed, they can never themselves be recreated.
They have scant access to water for six months of the year, creating a harsh, alkaline environment that has led to the evolution of desertlike flora in the middle of a hot, wet country. McDonald calls them “Dr. Seuss-type plants,” ones that look and behave like cactuses and succulent desert flora, but are related to the local tropical foliage.
There are fat, succulent grapevines, fig trees with thick, waxy leaves, and false cactuses — as spiky and segmented as those that grow in the American desert, but actually members of the poinsettia family that evolved independently. Perhaps most unusual are the large, phallic flowers known as Amorphophallus, which look like a cross between an orchid and a Muppet’s nose.
The toughest and most determined plants nestle themselves into the fissures and cracks atop the karsts, or cling to the razor-sharp outcroppings exposed to
the wind and sun. More delicate tropiry cal flowers — featherorchids white touch-me-nots — make homes in the grottoes within, sucking up the water that drips through the limestone. At the bottom, the karsts are like Swiss cheese, full of water-carved pockets that open up into large underground lakes where rare bats feed and mushrooms grow.
Over four days in January, armed with rice sacks and pruning shears, McDonald and several colleagues and students pored over two linked karsts, Phnom Kampong Trach and Phnom Domrei, climbing atop their jagged surfaces and passing all the way through them in a network of caves.
McDonald, 62, is a plain-spoken Texan with a mystical streak who spends his spare time working on a 1,000-page manuscript on the religious iconography of the lotus. He can clamber up and down the slippery, precipitous karsts like one of the mountain goats that live here (another anomaly in flat Cambodia).
Ultimately, over the course of two botanical excursions, the group found more than 130 species of vascular plants native to this patch of limestone, a comparatively rich assortment, including some thought to be new to science: an Amorphophallus and another related flower, a new type of jasmine, and a member of the coffee family.
Along with discovering these rare species, the scientists wanted to document the karsts’ biodiversity and the ways in which different parts of the habitat work together before it is gone. Ultimately, they hope to persuade the government to make these two karsts a protected area and declare them off-limits to future cement quarrying.
The team was accompanied by a representative of the Ministry of Environment who was to report back to his superiors on the merits of the protection proposal. The ministry is bereft of plant experts, so they sent Neang Thy, the country’s leading herpetologist, instead.
“The vegetation you see here, you may not see anywhere else,” he said. “If it is destroyed, that is a problem.”
He said he hoped future trips would allow for a survey of animal life in the karsts. Similar limestone formations in Vietnam and Thailand are home to novel species of fish, lizards, crabs and insects that adapt to life inside caves by becoming pale, blind and wingless, often looking very different from their aboveground brethren.
There are highly biodiverse karsts scattered across Southeast Asia, from Vietnam to Borneo, like desert islands surrounded by oceans of tropical rain forest. The destruction of karsts at the hands of cement companies, developers and tourists is a problem throughout the region.
But it is particularly acute here, where government regulation is lax and the state of local scientific knowledge fledgling.
“They are threatened, as they are elsewhere, but the difference is that there is almost nothing known about the biodiversity of the hills” in Cambodia, said Tony Whitten, the international regional director for Fauna and Flora International’s Asia-Pacific division.
Cambodia has almost no botanists and the study of plants in the country came to a standstill from 1970 to 1992 during an extended period of war and unrest punctuated by the trauma of the Khmer Rouge takeover from 1975 to 1979.
After the fall of the Khmer Rouge in 1979, Ken Sam An, a 61-year-old native of a village just below the Phnom Kampong Trach karst, spent years working for a limestone quarrying company, but now he serves on a local committee that tries to preserve the karsts, urging local residents to stop stripping them and chopping off rocks to sell.
“I tell them, ‘If you break the mountain, it’s not good for the environment, and if you work in tourism you can come and sell things to the tourists instead of breaking rocks.’”
Altogether, the caves are thought by locals to be chambers in the stomach of a dragon that beached here when an ancient sea receded thousands of years ago — a tale not entirely different from the stories told by geologists and botanists.
“This is what we lose when they take out a mountain,” McDonald said.