Tropical Plant Destruction Ahead of Schedule, Says UC Irvine Study

Four percent of Latin America’s tropical plants and 22% of the world’s tropical orchids have become extinct, and their disappearance is occurring faster than scientists had predicted, a UC Irvine study has concluded.

“We’re ahead of schedule,” said one of the study’s authors, Harold Koopowitz, a conservation biologist and expert in tropical plants, particularly orchids.

Koopowitz and his colleague, UCI graduate student Alan Thornhill, found that 2,715 of an estimated 65,000 Latin American tropical plants have become extinct, and species continue to die out at the rate of 84 to 168 a year.

He said his research, presented at a recent meeting of the Society for Conservation Biology, is one of the first efforts to make a precise estimate of the rate at which species are being lost. The rate is higher than many researchers had expected, he said.

“We’re going to lose the specialist species,” Koopowitz said. “They’re the oddballs, the gee-whiz things in biology, the things you go to zoos to see. They’re the things that make the planet rich.”

Thomas Lovejoy of the Smithsonian Institution, an authority on tropical forests, said that Koopowitz’s study “makes sense--sad sense.”

Lovejoy, who was a member of the U.S. delegation at the Earth Summit in Rio de Janeiro, said Koopowitz’s findings might underestimate the rate of loss because the exact number of species in the tropics isn’t known.

Koopowitz’s findings come from a computer model he and Thornhill developed that uses detailed data on the distribution of plant species.

About 15% of Latin America’s tropical forests have been cut, Koopowitz said. By combining that with the plant distribution data, he calculated that 4% of the tropical plant species have disappeared.

Koopowitz also used the computer model to determine rates of extinction among the 25,000 species of tropical orchids. He calculated that 5,477, or 22%, of the world’s tropical orchids have become extinct.

“They’re one of the few plants people get excited about,” he said, though not all tropical orchids have large, attractive flowers. About 55 species will be lost each year if forests continue to be cut at present rates, he said.