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Author Biography: Dr. Michael Novacek is senior vice president and provost of science at the American Museum of Natural History. He is also the curator of the Department of Vertebrate Paleontology, and is a specialist on fossil mammals.
Section One: What Have We Lost, What Are We Losing
Introduction MICHAEL NOVACEK
When it comes to biodiversity, ignorance is not bliss. In this section we acknowledge the depth of our ignorance about life on this planet. Yet enough is known to indicate life in crisis. The authors cast the ongoing loss of habitats and species in dire terms, on a scale comparable to the mass extinctions of the past. It is as normal for species to become extinct as it is for new species to evolve. Both the rates of evolution and extinction of species are relatively low. In periods of mass extinction, it is the increased rate of extinction that is significant. For example, Norman Myers claims that the current rate of species loss is probably 10,000 times greater than that of the background extinction rate, or the normal extinction rate. It is also possible to identify in many dimensions just what we are losing, namely, the enormous benefits of biological diversity in terms of ecosystem services, products for human health and consumption, and enhancement of the quality of life in both economic and aesthetic terms. As Edward O. Wilson notes in the opening essay of this section, wild species are the source of forty percent of our medicines, and all species offer unique insights to science. Indeed, as Francesca T. Grifo emphasizes, biodiversity is not only a priceless source of pharmaceuticals, it is critical to maintaining safe water supplies and controlling disease-causing organisms. The integral importance of millions of species to maintaining processes essential forlife—control of toxins and harmful microbes, soil decomposition, and recycling of nutrients and atmospheric gases—is a recurrent theme in essays by Norman Myers, Paul R. Ehrlich and Simon A. Levin, and Peter H. Raven. It should be remembered, however, that the benefit of a given ecosystem is not simply a function of how many species live in a particular region. David Ehrenfield vividly describes the unspoiled Soper Valley in Baffin Island, Canada, which remains an environment with its "... own kind of grandeur and glory, a living presence that surely makes an equally powerful claim on our care and affection," despite the low number of species.
Ignoring, or irresponsibly exploiting, these benefits—medicinal, economic, or aesthetic—has drastic effects. Robert Repetto explains why unsustainable logging practices not only create unnecessary waste of trees and other forest products, but also increase greenhouse gases through burning of huge tracts of tropical forests. Thus loss of species does not only translate to loss of valuable natural habitat; as Peter Raven notes, this crisis threatens the basic physical system of the planet, involving the recycling of chemicals in the soil, oceans, and atmosphere. As all the contributors stress, one way to mitigate the massive degradation and destruction of habitats is to infuse conservation action with fundamental scientific discovery. Thomas Eisner describes developments in molecular biology and biochemistry that help scientists identify chemicals that are used by species in defense against predators and other adaptations. Chemical substances once discovered can be used in their natural state or can provide a model for synthesized compounds. The current range of such chemical applications is impressive and the potentials for chemical exploration of the biosphere are extraordinary. Such work puts a tangible value on biodiversity in terms of human need, and moves us from short-term, indiscriminate harvesting of habitats toward bio- exploration and sustainable harvesting of new products. Science must set the framework for such sustainable programs. For example, comprehensive scientific data on population sizes and viability in species of ocean fishes and other marine life can identify both good and bad management, as effectively shown in the Audubon Guide to Seafood compiled by Carl Safina. The contributors to this section as well as the scientists, artists, and educators profiled have dedicated their careers to the advocacy of sound, scientifically based conservation of biodiversity. It is hoped that their words will inspire future generations of biodiversity scientists as well as policy makers.
Why is biodiversity in crisis?
In a careful examination of these questions, the authors describe the current biodeversity crisis and assert the need to protect species and ecosystems for the health of the planet and our own health and well-being, including an aesthetic appreciation of the natural world.
Wildlife in Trouble
EDWARD O. WILSON
Around the world, biodiversity—defined as the full variety of life, from genes to species to ecosystems—is in trouble. Not a week goes by without reports of the imminent end of one species or another. For every celebrity animal that vanishes, biologists can point to thousands of species of plants and smaller animals either recently extinct or on the brink.
There is not one country, not one biome and its plant and animal life— mountain, desert, or ocean—that remains untouched. The rarest bird in the world, the Spix's macaw, is down to one or possibly two individuals in the palm and river-edge forests of central Brazil. The rarest plant is Cooke's kokio of Hawaii, a small tree with orange-red flowers that once lived on the dry volcanic slopes of Molokai. Today it exists only as a few half plants— branches grafted onto the stocks of other related plants. Despite the best efforts of scientists to save the plant, no branches planted in soil have sprouted roots.
It is difficult to estimate overall rates of extinction. However, biologists generally agree that on the land, at least, and on a worldwide basis, species are vanishing one hundred times faster than before the arrival of humans. The world's flora and fauna are paying the price of humanity's population growth.
Biodiversity is in serious trouble. Responding to the problem, conservation experts have shifted their focus in the past twenty years from individual plant and animal groups (species) to entire threatened habitats, whose destruction would cause the extinction of many species. Such "hot spots" have become the focus of conservation efforts. The logic of the experts is simple: By concentrating conservation efforts on such areas, we can save the largest amount of biodiversity at the lowest economic cost. The outright elimination of habitats is the leading cause of extinction. But the introduction of exotic species and the diseases they carry follows close behind in destructiveness, along with overhunting or overharvesting of plants and animals. All these factors work together in a complex manner. When asked which ones caused the extinction of any particular species, biologists are likely to give the Murder on the Orient Express answer: They all did it. A common sequence in tropical countries starts with the building of roads into wilderness. Land-seeking settlers pour in, clear the rain forest on both sides of the road, pollute the streams, introduce alien plants and animals, and hunt wildlife for extra food. Many native species become rare, and some disappear entirely.
People commonly respond to the evidence of species extinction by entering three stages of denial. The first is, simply: Why worry? Extinction is natural. Species have been dying out for billions of years without permanent damage. Evolution has always replaced extinct species with new ones.
These statements are true—but with a terrible twist. After each of the four greatest environmental disruptions that occurred during the past 400 million years, evolution needed about ten million years to restore Earth's biodiversity. Worse, evolution will be even slower if natural environments have been crowded out by artificial ones. Faced with such a long waiting time, aware that we have inflicted so much damage in a single lifetime, our descendants are going to be—how best to say it?—peeved with us.
Entering the second stage of denial, people ask: Why do we need so many species anyway? Why care, especially since the vast majority are bugs, weeds, and fungi?
It is easy to dismiss the creepy crawlies of the world. However, the value of the little things in the natural world has become extremely clear. Recent experimental studies on whole ecosystems support what ecologists have long suspected: The more species living in an ecosystem, the higher its productivity and the greater its ability to withstand drought and other kinds of environmental strain. Because we depend on working ecosystems to cleanse our water, enrich our soil, and create the very air we breathe, biodiversity is clearly not something to discard carelessly.
Besides creating a livable environment, wild species are the source of products that help support our lives. More than forty percent of all prescription medicines used by Americans are substances originally extracted from plants, animals, fungi, and microorganisms. Aspirin, for example, the most widely used medicine in the world, was originally derived from the willow tree.
Every species on Earth is a masterpiece of evolution, offering a vast source of useful scientific knowledge because it is so thoroughly adapted to the environment in which it lives.
Even when that much is granted, the third stage of denial usually emerges: Why rush to save all the species right now? We have more important things to do. Why not keep live specimens in zoos and botanical gardens and return them to the wild later?
The grim truth is that all the zoos in the world today can hold a maximum of only 2,000 species of mammals, birds, reptiles, and amphibians, out of about 24,000 known to exist. The world's botanical gardens would be even more overwhelmed by the quarter million plant species. To add to the difficulty, no one has come up with a plan to save all the insects, fungi, and other ecologically vital small organisms. And even when scientists are finally ready to return species to independence, the ecosystems in which many live will no longer exist. The conclusion of scientists and conservationists is practically unanimous: The only way to save wild species is to maintain them in their natural habitats. Considering how rapidly such habitats are shrinking, even that straightforward solution will be an overwhelming task.
In spite of all these difficulties, there is reason for some optimism. With appropriate measures and the will to use them, the destruction can be slowed, perhaps eventually halted, and most of the surviving species saved. Some of the most important steps that can be taken are outlined in the Convention on Biological Diversity signed by 156 nations and the European Union at the 1992 Earth Summit in Rio de Janeiro. The convention was the turning point in the awareness of biodiversity as a world issue. Besides speeding up conservation efforts, the convention awakened many tropical countries, where biological diversity is both the richest and the most threatened.
The new approach to biodiversity preservation, uniting conservation and economic development, is not perfect, and it is not yet fully practiced in any country. But it is a promising start. Some of the test projects have succeeded dramatically. They offer a way out of what will otherwise be a biologically barren future. With the world population at six billion and sure to keep on growing rapidly, humanity has entered a dangerous environmental bottleneck. We hope-surely we must believe-that our species will come out the other side in better condition than when we entered. We should make it a goal to take as much of the rest of life with us as is humanly possible.
In what ways can the economic stability of a highly diversified corporation be compared to the ecological stability of an ecosystem with a high degree of biodiversity?
Over forty percent of all prescription medicines used by North Americans are from substances originally extracted from the world's biodiversity. Find out what some of these medicines are and where they come from.
|Sect. 1||What Have We Lost, What Are We Losing?|
|Biodiversity: Wildlife in Trouble||18|
|Profile: Abebe Getahun||21|
|What's This Biodiversity and What's It Done for Us Today?||22|
|Case Study: The Audubon Guide to Seafood||27|
|Deforestation in the Tropics||32|
|Biodiversity and Human Health||40|
|Profile: Kevin Browngoehl||45|
|Biodiversity: What It Is and Why We Need It||46|
|Case Study: The Green Guerillas, New York City||55|
|What Have We Lost, What Are We Losing?||58|
|Profile: Amy Vedder||63|
|Chemical Prospecting: The New Natural History||64|
|Profile: Dolores R. Santoliquido||71|
|Sect. 2||Extinctions Past and Present|
|Evolution, Extinction, and Humanity's Place in Nature||76|
|Case Study: St. Lucia Parrot Recovery||81|
|Profile: Clare Flemming||83|
|The 40,000-Year Plague: Humans, Hyperdisease, and First-Contact Extinctions||84|
|Prehistoric Extinctions and Ecological Changes on Oceanic Islands||90|
|Case Study: Brown-Eyed, Milk-Giving ... and Extinct: Losing Mammals Since A.D. 1500||95|
|Global Warming, Loss of Habitat, and Pollution: Introduction to "Thompson's Ice Corps," "Nest Gains, Nest Losses," and "Hormonal Sabotage"||100|
|Thompson's Ice Corps||106|
|Nest Gains, Nest Losses||112|
|Case Study: Lake Victoria||117|
|Case Study: Reefs in Crisis||127|
|Sect. 3||Saving Biodiversity: Strategies and Solutions|
|The New Geologic Force: Man||134|
|Profile: Jane Goodall||139|
|Case Study: Humpback Whale Conservation Genetics Project, Madagascar||141|
|Conservation Biology and Wildlife Management in America: A Historical Perspective||144|
|Profile: Jaime A. Pinkham||149|
|Managing the Biosphere: The Essential Role of Systematic Biology||150|
|Case Study: Wilderness Preservation Act, U.S.A.||155|
|How to Grow a Wildland: The Gardenification of Nature||156|
|Case Study: The Belize Ethnobotany Reserve Project||163|
|Profile: Penelope Bodry-Sanders||165|
|The Economic Value of Earth's Resources||166|
|Profile: Michael Balick||175|
|Case Study: Jaguars||177|
|Strategies and Solutions: Mapping the Biodiversity||180|
|Community-Based Approaches for Combining Conservation and Development||184|
|Case Study: Restoration of the Elwha River by Dam Removal, Washington||189|
|No Free Lunch in the Rain Forest||192|
|About the Hall of Biodiversity||197|
|About the American Museum of Natural History||206|