Environment : Life and Death in the Rain Forests : Species may be disappearing at a rate of more than one an hour. Alarmed conservationists have a new strategy for preservation.

Al Gentry had no idea as he struggled toward the isolated Ecuadorean outcropping in 1982 that the name “Centinela Ridge” would become infamous in the literature of biology.

A botanist with the Missouri Botanical Garden, Gentry was on a field trip. And he was understandably excited when he discovered that the ridge at the base of the Andes nurtured more than 100 previously unknown species of plants.

Unfortunately, that’s only part of the reason Centinela Ridge became a scientific cause celebre . The other part is that shortly after Gentry’s find, the ridge was cleared by farmers, and nearly all those unique plants disappeared forever.

It’s a story of destruction that has been repeated countless times since, throughout the tropics. Deforestation, population pressures and pollution in key parts of the world are combining into what British conservation consultant Norman Myers calls an “impending extinction spasm.”

The World Wildlife Fund, a major conservation group, estimates that in 1970 species were becoming extinct at a rate of one a day. This year, biologists warn, the rate may be more than one an hour.

Not only has that increase alarmed conservationists; it has also fostered a whole new approach to the challenge of preserving the 1.4 million different types of plants, animals, bugs and other living things already identified by scientists, as well as the millions more species still believed to be lurking, undetected, on other Centinela Ridges.

There’s always been a lot of nastiness in nature, of course, and species have come and gone since the world began without destroying the precariously balanced, wider communities of animals, plants and bacteria--or ecosystems--of which they were a part.

But for some 65 million years, extinctions through natural processes were remarkably low, an estimated rate of one species wiped out every 27 years. Man began to alter that rate about 15,000 to 35,000 years ago, scientists believe.

But what is happening now is of an entirely different order because of destruction of tropical forests and coral reefs which are home to a disproportionate share of the Earth’s living species.

“If we continue the way we are going,” said Jared Diamond, a UCLA physiologist and ecologist, “it is likely that more than half of all species will be extinct by the middle of the next century.”

That prospect puts a different twist on one of the most urgent environmental questions facing world leaders. Until now, concerns about the tropical forests have mainly focused on the problem of global warming: Felled trees cannot absorb carbon dioxide, and when they’re burned, or if they rot, they release it in great quantities, which may be adding to the greenhouse effect.

But conservationists increasingly point to another global threat from deforestation: the erosion of biodiversity, a term that simply refers to the wealth of life on Earth, the millions of organisms, the genes they hold and the ecosystems they help build and maintain.

While global warming is still a subject of much debate, biologists argue that species loss is both undeniable and a more immediate threat, not just to people in the tropics but to city dwellers in faraway countries who depend in ways they often don’t realize on sometimes obscure life forms halfway around the globe.

The threat to this web of nature--and what that means to human survival itself--has galvanized the conservation movement as it heads into a new decade.

Major forest areas have already been virtually written off by some biologists. As much as 90% of Madagascar’s forests are gone. Almost all of the forests in the Philippines have been destroyed or degraded, scientists say. The number of species lost in these two areas alone is considered to be enormous.

“The world is losing much more of its virgin tropical forests than had been thought,” the World Resources Institute said in a report this summer. “This loss is occurring despite a surge of international concern to conserve the rain forests.”

Using new data based on ground surveys of tropical forests, low-altitude photographs, satellite systems and side-looking radar, the resources institute concluded that deforestation is taking place 50% faster than the best previous scientific estimates showed.

The Brazilian Satellite Research Institute says that 8% of Amazon Basin rain forest has been destroyed, up from 5.8% announced last year. The new figure is the equivalent of a landmass about the size of Sweden.

In one sign of concern, experts on tropical ecosystems, agriculture and mining spent six days in Manaus, Brazil, last week for a “Forest 90” conference on ways to ease the adverse environmental impact of economic development.

“The losses have become so great, so rapid that we have to reorder our priorities,” said Russell A. Mittermeier, president of Conservation International, in an interview. “We have to approach this with the same dedication, zeal and urgency we showed when we sent a man to the moon in the 1960s.”

Moreover, there is danger that without action, the worst habitat destruction and exterminations are still to come. Modern technologies of forest clearing, such as chain saws, herbicides, dynamite and bulldozers, are being widely introduced in developing countries. “We are just starting in earnest to destroy tropical rain forests,” said UCLA’s Diamond.

Also, another 959 million people are expected to be added to the world’s 5 billion population during the next decade--most of them in the very parts of the world that are home to the greatest number of species.

Traditional conservation called for setting aside large areas as preserves, and putting rangers inside them to patrol vigorously and keep human activity limited to game-watching from Land Rovers. Fund-raising concentrated on the big and beautiful species, the “flagships” like tigers, pandas, elephants and gorillas. Efforts went into rescuing endangered species and keeping the scenery intact.

It hasn’t worked.

Parks in the Third World have been overrun by poachers, miners and settlers--animals slaughtered and rangers outgunned.

At the heart of the new conservation approach is a disarmingly simple strategy, a list of top priorities for preservation, the world’s biological “hot spots” and “good news” areas.

These terms were coined by British ecologist Myers and have since taken on a life of their own. The hot spots are parts of the world with the most biodiversity that are also the most threatened by humans. Focus on these, the strategy says.

The good news areas are the vast tracts of still-unspoiled wilderness, mainly in the northern Amazon Basin, the Zaire Basin in Central Africa and Papua New Guinea. There, the new strategy aims to retain these areas in a pristine state, while still meeting the needs for growth in the host countries.

Conservationists say that even for these untouched areas, time grows short.

“The 1990s offer a final chance to protect tropical rain forests before economic and demographic problems in developing countries spiral out of control,” Conservation International said in a plan to save threatened ecosystems released earlier this year. “The next 10 years represent a decade of opportunities that will not be repeated.”

The concentration of biodiversity in the tropics, while once thought of as a liability because of the intractable economic and population pressures there, could prove to be an asset, the strategy holds. Only a handful of governments have to be dealt with. Conservation International estimates that 60% of the planet’s total biodiversity is found within just 12 countries--all of them poor and in heavy external debt.

That, to the new conservationist, means leverage. If the rich, industrialized countries can cut a deal with the biologically favored countries, there’s hope of success to preserve biodiversity.

For example, the total annual interest that tropical countries must pay on their collective national debts is an estimated $100 billion. To satisfy their lenders in the developed world, many of the debtor nations are over-cutting their forests and cashing in their minerals.

An obvious alternative to the destruction, conservationists say, is to buy up that debt, relieve the pressure to destroy habitats, and financially aid rural people. Thus have been born debt-for-nature swaps. Conservation groups and industrial nations have begun buying up debts of Third World countries--at a very favorable discount since banks will settle for 10 cents or less on the dollar to close these shaky loans--and then donating this money back to the host country to buy up nature preserves and raise the standard of living of people who would be most likely to plunder them.

Traditional conservation also made little effort to involve people who lived or settled near nature preserves.

Admitting this failing, conservation groups have taken a new approach. As posed by the World Resources Institute, a large and well-funded policy research group in Washington, the fundamental new question is this:

“How can societies meet basic human needs and nurture economic growth without undermining the natural resources and environmental integrity on which life, economic vitality and international security depend?”

The new stress is on sustainable exploitation of nature and grass-roots economic aid. Dwindling into the background, albeit too slowly, critics charge, are the mega-projects--big dams that wipe out habitat and displace rural people, or high-tech investments like nuclear power plants, which sink already indebted nations deeper into the hole.

Conservationists point out, for example, the extent to which rural people depend on natural resources for survival. If wilderness areas are viewed as vital national assets, they will be less likely to be flooded out or sawed down.

In Botswana, for example, about 50 species of wild animals provide about 40% of the nation’s diet, according to a recent study on biodiversity by the World Bank and four major conservation groups. In Ghana, 74% of the population depends on wildlife for protein--from fish to caterpillars. And in Nigeria, rural people annually consume about 100,000 tons of giant rats known as “grass cutters.”

Wilderness has other direct uses. Natural vegetation traps and stores water for both agricultural and urban uses. It also prevents erosion and mudslides, which can have catastrophic consequences in rural areas.

By stressing the multiple benefits to millions of poor and rural people from natural ecosystems, conservationists hope to build opposition to timber concessions and grand schemes, such as hydroelectric projects, favored by cash-hungry central governments.

“It’s becoming a human rights issue, not just problems of losing green fuzzies and warm wuzzies,” said Nels Johnson, a biodiversity project coordinator for the World Resources Institute. “We’re seeing more connections between human rights and conservation.”

Simultaneously, a rise in democracy in some key countries has allowed indigenous environmental groups to flourish and gain political clout--a genuinely new movement in the Third World.

The conservation strategy of the 1990s calls for working with these groups, giving them funds and a myriad of resources, such as scholarships in this country to train people in conservation.

Conservation International, for example, is working with the Bolivian government and the nomadic Chimane Indians to both improve the Indians’ living standard and develop a management plan for the 4-million-acre Beni Biosphere Reserve, which protects thousands of plant and animal species and is home to the Chimane people.

In a related effort, the World Wildlife Fund has stepped up its efforts to finance private conservation groups in Latin America and the Caribbean.

“Fifteen years ago, private Latin American groups were barely a factor in conservation,” the World Wildlife Fund said in a newsletter to its members. Now, a directory put out by the Brazilian government lists 2,000 conservation groups in that country alone.

There are other reasons for hope, according to many conservationists.

Government and private funding for conservation is soaring. The World Wildlife Fund had an annual budget of $9 million and a membership of 94,000 in 1983. Last year it had a budget of $35.6 million and 667,000 members. The U.S. Agency for International Development, a key funding outlet, asked Congress for a 30% budget increase for environmental activities in 1991, to a total of $370 million.

Several countries with the most biodiversity, especially Mexico and Brazil under the new regime of President Fernando Collor de Mello, have taken steps to put curbs on deforestation. It’s not enough to satisfy critics, but their actions at least show a new attitude.

President Bush wants a U.N. convention on forests within two years that, among other goals, would address “subsidies and other market distortions which inadvertently encourage deforestation.”

Conservationists argue that two years is too long to wait. They are also wary of a “big science” approach to preserving biodiversity, such as a proposal by the National Aeronautics and Space Administration to spend $50 billion for six huge satellites that would monitor the Earth’s environment.

“For that amount of money, we could come very close to solving the whole biodiversity problem,” said Conservation International’s Mittermeier. “Why should we just stand idly by on the sidelines and watch the destruction?”

Compared to defense budgets and Mars missions, some proposals by conservationists seem quite modest in cost. The joint study by the World Bank and conservation groups estimated that a worldwide network of 500 new wildlife reserves, primarily in tropical countries, could be established for $500 million to $1 billion. The annual maintenance cost would be from $100 million to $300 million a year.

“The jury is still out,” said David Wilcove, an ecologist with the Wilderness Society. “We are heading for some rough times in trying to both protect and manage the tropical forests. We still have to find out if we can manage them on a sustainable basis.”

But activist biologists, such as Harvard’s Edward O. Wilson, warn that the industrial nations have little choice but to push ahead with a strategy to reverse the extinction trend. The cost to the human species of not acting, he said, will be “beyond calculation and certain to be harmful.”

Times researcher Janet Lundblad contributed to this story.

Next week: Preserving the Amazon.

Why Fret About the Survival of Endangered Bug or Blossom?

To biologists, no species is expendable. If periwinkles, neon-colored toads and bark beetles disappear in remote swamps and glades, they say, it is also a blow to condominium dwellers who never knew or cared that the organisms existed.

The reason: It’s often the obscure and ugly bits of life--a wasp, rare tree or piranha--that sustain the health of an entire biologic community, such as a swamp, a coral reef or a mountain plateau. And wilderness habitats supply in many, often subtle, ways the most basic human needs of urban populations.

Agriculture, for example, depends on constant crossbreeding with wild species to increase yields and find new defenses against diseases and pests that have developed immunities. Without access to sources of fresh genetic material from the Third World, farm output worldwide would rapidly decline.

Swamp forests and mangroves are valuable nursery grounds for fisheries, and fish is an essential protein in many parts of the world.

One-quarter of prescription drugs in the United States contains a compound derived from nature. Chemists are constantly reaching into the rain forests for new medicines.

Other non-timber forest products include natural rubber, waxes, oils, forage, fibers, fuel, silk, thatch, resins, feathers, stock for nursery plants and pets, and a variety of foods from cocoa to nuts.

Countries with the Highest Numbers of Species of Mammals

Indonesia: 515 Mexico: 449 Brazil: 428 Zaire: 409 China: 394 Peru: 361 Colombia: 359 India: 350 Uganda: 311 Tanzania: 310

Countries with the Highest Numbers of Species of Birds

Colombia: 1,721 Peru: 1,701 Brazil: 1,622 Indonesia: 1,519 Ecuador: 1,447 Venezuela: 1,275 Bolivia: 1,250 India: 1,200 Malaysia: 1,200 China: 1,195

Countries with the Highest Numbers of Species of Amphibians

Brazil: 516 Colombia: 407 Ecuador: 358 Mexico: 282 Indonesia: 270 China: 265 Peru: 251 Zaire: 216 U.S.: 205 Venezuela/Australia: 197

Countries with the Highest Numbers of Species of Reptiles

Mexico: 717 Australia: 686 Indonesia: 600 Brazil: 467 India: 453 Colombia: 383 Ecuador: 345 Peru: 297 Malaysia: 294 Thailand/Papua New Guinea: 282 Source: Conservation International

Times researcher Janet Lunblad contributed to this story.