Biogeography Begets Biodiversity main content.

Biogeography Begets Biodiversity

Biodiversity scientists working in Vietnam have made a remarkable number of discoveries in recent years. Of the more than 155 amphibians known to live in Vietnam, 26 have been described since 1997. More than 200 mammals have been recorded in Vietnam, several of which—including a wild pig; a striped rabbit; three species of barking deer; the Tonkin snub-nosed monkey; and the saola, a recently described wild oxen —are found only in Vietnam or neighboring countriessuch as Laos, Cambodia, and China. Botanists have identified and cataloged 9,000 of the more than 12,000 plant species thought to exist in Vietnam. Of these, perhaps as many as 10 percent are believed to grow only within the country’s borders. Analysis of these collections has yielded 200 previously undescribed taxa.  In addition, Vietnam is home to nearly 900 species of birds. And discoveries of new species continue: in the past 10 years, three new large mammal species and three new birds species have been discovered in the Truong Son mountain region of central Vietnam. “The extraordinary richness of Vietnam’s biodiversity is only starting to be fully appreciated, as ongoing discoveries are being made at a rapid pace,” says Raoul Bain, a biodiversity specialist with the Center for Biodiversity and Conservation at the American Museum of Natural History. “Its rich biodiversity is due to Vietnam’s diversity of habitats.”

Discovered in surveys during 2005 and 2006, this rare leafless orchid, Gastrodia theana, lives only in the central Vietnamese lowlands. It was named after its discoverer, botanist Pham Van The.Leonid Averyanov/WWF Greater Mekong

The diversity of habitats in turn is the product of geological and climatic changes that have unfolded over millions of years. Vietnam lies in the tropics, between 8 and 23 degrees north latitude. Through geologic time, when glaciers periodically wiped out the flora and fauna at high altitudes and high latitude areas, tropical lowlands have remained warm, moist nurseries and havens for evolving plants and animals. This is one reason tropical areas support more species than similarly sized areas farther to the north or south.

In addition, Vietnam is situated at the meeting place of three converging continental plates: the Eurasian, the Indo-Australian, and the Philippine Sea. Over hundreds of millions of years, these plates migrated across Earth’s surface and collided, bringing together a disparate assortment of plant and animal species. Over subsequent eons, the sea level rose and fell; mountains grew upward, then shrank through erosion; river courses naturally shifted; and the variety, size, and locations of forests changed with alterations in the climate. Vietnam’s habitats and environments have been evolutionary nurseries for new and unique species. Understanding the relationship among species, where they are found, and the environments where they evolved is termed “biogeography.” 

Having pieced together Vietnam’s biogeographic history, and with it some understanding of how the country’s known species came to live where they do, biologists are better equipped to pinpoint biogeographic zones where new species might be found. One such zone is the Truong Son mountain range, which lies in western Vietnam along the border with Laos and Cambodia. Monsoon rains from the South China Sea fall year-round on the eastern slopes, enabling lush, evergreen forests to grow at high elevations. The western slopes, which are sheltered from the rain, support plants and animals that have adapted to a drier, more seasonal climate.

The Kon Tum Plateau, a region of steep mountains and wet forests in Vietnam’s central highlands, also supports tremendous biological diversity. Many of the species found there appear related to animals and plants in Malaysia and tropical Indonesia, an indication that they all share common evolutionary roots.

Because it is home to diverse species from a number of distinct groups including invertebrates, mammals, birds, fish, reptiles, and frogs, Vietnam offers a unique opportunity for conservation. By conducting biological surveys, scientists hope to identify regions within Vietnam whose high biodiversity value calls out for aggressive conservation measures. “The areas of remaining forest in our country are not large,” says Phan Ke Loc, a botanist with Vietnam’s Institute of Ecology and Biological Resources. “So we must carry out the work of inventory very quickly, the faster the better. Vietnam is pushing for botanical diversity because we understand that every effort of humankind, has always been and always will be, utterly dependent on biological diversity.”