Race to document rare plants

Most of the wood in mainland Southeast Asia has been logged to support the region’s rapid economic growth. Efforts are on to document the rare plant life found in Cambodia’s limestone karsts that are next in line, writes Julia Wallace.

Millions of years ago, a cluster of coral reefs stood firm at Kampong Trach mountain in Cambodia, 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 specialised 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.

Sanctuaries of rare species
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. 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 harbours for a specialised 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, USA, who is spearheading the plant collection project with support from the International Union for Conservation of Nature, Switzerland. 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 desert-like flora in the middle of a hot, wet country. Andrew 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.

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 tropical flowers 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, Andrew and several colleagues and students poured over two linked karsts, Phnom Kampong Trach and Phnom Domrei. 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: 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.”

In Kampot, the scientists were led through some of the more treacherous cave networks by Ken Sam An, a 61-year-old native of a village just below the Phnom Kampong Trach karst. He knows more about these caves than just about anyone else. As a teenager, he watched as the Viet Cong hid in the caves, resulting in retaliatory bombing campaigns by the United States that drove the population to flee. Soon, ultra-Communist rebels swept into the area and he was conscripted into a Khmer Rouge youth unit. Whatever scientific research apparatus still existed was totally dismantled by the victorious Khmer Rouge government.

After the fall of the Khmer Rouge in 1979, Ken 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.’”

Bigger risks
A far bigger risk is large-scale limestone quarrying by companies producing cement. The cement firms have also spawned a mini-land boom in Kampot, where prices have risen thirtyfold in the last decade, according to locals. In interviews, the inhabitants complained that rocks being blasted off the mountains were falling on their homes and angering the local neak ta, who had to be propitiated with offerings of roast pigs.

Tony Whitten, the international regional director for Fauna and Flora International’s Asia-Pacific division, said he had tried for years, fruitlessly, to determine whether environmental impact assessments had been carried out before cement companies were given permission to dynamite the karsts. The Ministry of Mines and Energy, which is responsible for granting and regulating concessions for limestone quarrying, declined to comment.

Even when environmental assessments are conducted, they often focus on large mammals, overlooking plants and small species that are highly endemic to certain caves. The slimy, squishy invertebrates and strange plants that live in karsts can be a hard sell to donors, who prefer what are known as “charismatic megafauna"— cute, easy-to-anthropomorphise animals like elephants, tigers and dolphins that appeal to the public. “It takes a botanist to appreciate the charisma of a plant,” Andrew said.

The karsts his group wants to protect have the advantage of already being a minor tourist attraction, with a Buddhist pagoda sprawling out at their feet, small shrines nestled into the caves and a set of stone steps leading down to an underground pond where monks bathe.