As the destruction of tropical rain forests accelerates, researchers have launched a last-ditch, crash program to catalog and map the biological richness of the planet.

Over the next few years, some of the world's best naturalists are to be deployed to dozens of locations, where, like ecological SWAT teams, the scientists plan to move quickly through uncharted forests, documenting every species of plant and animal they encounter. The first teams have already hit the ground in Peru and Bolivia.

The effort, organized by a loose confederation of conservation and science organizations, should give biologists a rough sense of the diversity and species richness of some of the most remote areas on Earth, they say. The idea is to produce a list of areas that support the greatest concentration of different species.

"It's a quick and dirty approach for investigating the hottest of the hot spots," said Edward O. Wilson of Harvard University, who has been advocating rapid assessments of the planet's biological diversity. "The time is now or never."

Wilson and other biologists maintain that despite the concern over the destruction of the rain forests, much of the tropical world remains unknown to science. And despite the rapid deforestation, there are still immense and little-known tracts of virgin forest. In parts of the upper Amazon, for example, a small plane can fly for hours over a forest canopy unbroken except for an occasional landing strip cleared by drug smugglers, missionaries or gold miners.

Moreover, conservationists say such rapid assessments are invaluable for making intelligent decisions about which areas to protect and which areas can be exploited by timber or mineral companies or maintained as "extractive reserves" for controlled harvesting of renewable resources. Indeed, because such ecological measurements have been rare in the past, some conservation groups have squandered resources to protect areas that are biologically mundane, while nearby forests with greater diversity were ignored. Bolivia Yields Surprises

Four tropical field biologists, considered by their peers to be among the most knowledgeable in the world, recently spent three weeks in the forests of western Bolivia. Despite the difficulty and dangers (one of the group contacted bubonic plague), the team was surprised to find a very high diversity of plants and animals. The scientists said it was remarkable to find so many plant and animal species so far south, as ecological dogma holds that biological diversity dwindles as one moves away from the equator.

"Here is a place that no one has ever talked about for conservation, but biologically, it's the richest part of Bolivia," said Ted Parker, an ornithologist at Louisiana State University's Museum of Natural Science who participated in the rapid assessment organized by the group Conservation International.

Parker encountered, for example, bird diversity rivaling the highest known in the world. In one lowland forest in western Bolivia, for example, Parker counted 403 species of birds -- nine of which biologists had not known were in Bolivia and 30 of which were recorded for only the second time. In the entire area, Parker said he expects a complete listing would exceed 1,000 species, or more than 10 percent of all known bird species on Earth. As a comparision, Parker said that a dedicated bird-watcher in North America could amass a "life list" of about 600 birds. Abundance of Mammals

Mammals, while harder to catalog on a short trip, were also abundant. Louise Emmons, the Smithsonian Institution mammalogist who contracted bubonic plague on the trip, but who recovered and is now studying tree shrews in Borneo, reported three species never recorded for Boliva: the spiny tree rat, the little big-eared bat and the short-eared dog, an elusive canine that may be the rarest mammal in Amazonia. Emmons believes the sighting of the short-eared dog in the wild was the first by a scientist.

The plant community was similarly rich. Robin Foster of the Smithsonian Tropical Research Institute and Alwyn Gentry of the Missouri Botanical Garden counted 204 plant species in a standard transect measuring about 6 feet by 150 feet. At least two of plants are entirely new to science.

"Anything over 200 is the maximum diversity recorded," Gentry said. "Only a handful of sites have over 200 plants in a transect."

According to Gentry, most of North America harbors about one-tenth the species richness. "You see between 18 and 21 species -- might get 25 in some locales, but that would be the maximum," he said.

Gentry and his colleagues, who include naturalists from the countries they visit, plan to explore about five sites a year over the next few years. Another group, based at the University of Kansas, plans to do similar assessments and has already completed its first, in Peru. Other ecological SWAT teams are being deployed by the Smithsonian and the Nature Conservancy. Coordinating Disciplines

In the past, biologists would study a site intensely for years, but would often focus on just one group of plants or animals. The new ecological accounting hopes to integrate plants and animals in the counts, including some work on insects.

"Every time we tried to assess what's known, we found that botantists had worked in one place, ant people worked in another place, mammal people in another, herpetologists in some other place. What we wanted was an intergrated approach," said William Duellman, professor and head of the neotropical diversity program the University of Kansas.

One problem, however, is that few people are qualified for the work. Most field biologists focus on certain groups and have only a passing familiarity with other plants or animals.

In the world, there are few botantists who can identify as many plants as Gentry and Foster can. Ornithologists, normally a competitive lot, say there may be two or three people in the world who, like Parker, can walk into the Amazon and identify every bird he encounters. To make matters more difficult, Parker does most of his identifications by listening to the bird's voice, because birds in the forest are notoriously inconspicuous. Mammalogist Emmons is said by colleagues to be able to smell which species of bat she is encountering.

"Where do you acquire this knowledge?" Parker said. "You don't learn it in school. You get it by going down to Peru for 10 years and sweating it out in the forest."