Biodiversity is a term used to describe the numbers of species, families and other biological divisions of life forms on Earth. Studies of this subject in various parts of the world will be discussed. Certain regions and countries in the world harbor very large numbers of plant and animal species, yet these same areas are threatened by habitat destruction. What is being done to preserve such areas will be explored. The importance of preserving biodiversity to human society and environmental balance is a major purpose of the project. A related topic integral to the study of biodiversity is the variety of ecosystems and environments that provide habitats for the great diversity of life on Earth and their protection.
As studies of the natural world have blossomed over the past century, scientists have documented Earth's amazing array of plants and animals, each species interrelated with others in its environment. Although life exists even in inhospitable environments, such as frigid mountain tops and hot springs, certain ecosystems, primarily tropical forests and coral reefs, harbor the greatest diversity of species. Research on the species of plants and animals in these areas is just beginning, but remarkable findings have emerged. In a single tree in Peru, for example, Dr. Edward O. Wilson, a famed biodiversity expert and entomologist, found 43 species of ants, a number equal to all the species of ants found in the British Isles.
Studies of biodiversity have increased in recent years, and one country, Costa Rica, is now carrying out a biological inventory of all its species, a massive and important task that may take a century. A study that has gone on since the building of the Panama Canal measures the decline in the number of species living on Barro Colorado Island as the waters of the Panama Canal rose around it. It has documented the loss of many wide-ranging species as the range grew smaller. Such studies add to the understanding of habitat requirements for various species and how the loss of some affects ecosystems as a whole. A study in the Brazilian Amazon measured the biodiversity of an extensive rainforest prior to cutting it into parcels of varying size to determine the effects on species (see Lovejoy et al. 1984). As a result of extensive deforestation, especially in tropical countries, many studies of forest fragmentation and its effects on biological diversity are taking place, finding that losses of even a few species can result in major ecological damage (see Laurance and Bierregaard 1997 and description in the Forests chapter). Biodiversity studies known as RAPs, or Rapid Assessment Programs, last only a few days and seek to identify areas of high diversity that are in danger of being destroyed. "Environmental S.W.A.T Team" is a film about biologists who conduct one of these RAPS, inventorying a tropical forest for Conservation International, an organization which was able to convince the country's government to protect a threatened region based on the results of the study (see Video section).
Brazil's Atlantic Forest, one of the world's most diverse environments, which once covered millions of square miles along the southern coast and well inland, has been reduced by 92 percent. Remnants of this forest have been found to harbor the greatest diversity of trees in the world: 476 species in a plot of only 2.5 acres. By contrast, a plot of similar size in a North American temperate forest has fewer than 80 species of trees. This is known as a "hotspot," or an area of great biological diversity. Others include forests in the Andes, Madagascar and Indonesia (see Mittermeier et al. 1999). A vast array of plants and animals can be found in the hot spots, including many extremely unusual and unique examples of evolution that are in imminent danger of extinction. New Caledonia, for example, an island in the southwestern Pacific Ocean, is home to a variety of plants and animals of ancient origin. It is a small portion of Gondwana, the southern supercontinent that broke up into pieces some 140 million years ago at the dawn of the age of birds. The ancestors of the most primitive avian families originated in Gondwana, and the Kagu, a bird still resident on New Caledonia, is a direct descendant (see Cracraft 2001). Related to cranes, rails and bustards, the elegant, gray Kagu is flightless, with a stunning pattern of wing and head crest feathers. It possesses characteristics so unusual that it has been placed in its own avian family. The Kagu is threatened with extinction along with scores of other ancient species on New Caledonia, many of which had survived for millions of years (see Threatened Birds of the World). This hotspot is in grave danger of losing diversity to nickel mining, feral dogs that kill the Kagus and other wildlife, and deforestation.
The huge growth in human population over the past century, now totaling some 6.5 billion, is responsible for colonization of previously remote wilderness areas and for providing a market for the decimation of ancient forests and rare wildlife for commercial purposes. Land is being cleared for grazing livestock and farming, while mining, industry, corporate logging and other development are obliterating species throughout the world. Forests have the largest number of threatened species of any habitat, although the oceans have scarcely been explored for biodiversity. Tropical forests throughout the world harbor about half the world's plants and animals on only 7 percent of the planet's land area. Hot spots also exist in temperate regions, such as the Appalachian mountains of the eastern United States, which have more types of salamanders than exist anywhere in the world, now threatened by pollution and logging. Rivers and waterways of the southeastern United States have the greatest number of mussel species in the world, but government dam and water projects have caused hundreds of extinctions. Grasslands, where only a century ago wild antelope, bison and other ungulates roamed in untold millions, have been converted into farms or pastureland for livestock, the wildlife killed off or driven away. In Earth's history, mass extinctions have occurred on at least five occasions, nearly obliterating the majority of life forms. These were natural events, but the present catastrophic situation is considered the sixth mass extinction, one that may end in destroying or seriously damaging the remaining rainforests, coral reefs and other precious centers of biodiversity within the next century (see Wilson 1988, Leakey and Lewin 1995). By some estimates, half of the estimated 5 million animals and plants that now exist, only a fraction of which have been scientifically identified, could be gone within a century.
Just as the diversity and ecological roles of species are beginning to be seen as components of an immense and beautiful living tapestry, the strands of this tapestry are unraveling. The disappearance of even a single species can result in extinctions of others dependent on it. For example, elephants and hornbills are the primary dispersers of many forest plant seeds, upon which a host of animals rely. Both are now in danger of extinction, threatening entire ecosystems. Thus, biodiversity is not an abstract concept, but a blueprint of the Earth's life forms. It is vital that its many parts be preserved. Once destroyed, many ecosystems, such as old-growth forests and other key environments, may never regenerate. In most such cases, our knowledge of diverse systems is inadequate to gauge just how many species--or which species--could disappear from an ecosystem before it collapses. Nor do we know how much genetic diversity a species can lose through loss of individuals before it can no longer adapt to changes in its environment. Drastic changes caused by human activities are outpacing research on such situations. The healthy functioning of ecosystems is key to human survival. Although the majority of biologists consider the loss of biodiversity to be the greatest problem facing humanity, few members of the public are even aware of this critical situation. Ignoring these experts' opinions of the precarious status of our planet's health, upon which our lives depend, is the equivalent of ignoring the opinion of a team of eminent doctors recommending urgent action to remedy an emergency medical condition.
Steps are being taken to preserve many critically important regions. Through acquisition of habitats and reintroductions of species, entire ecosystems are being saved. In a growing trend, countries are setting aside large new national parks and reserves. Suriname, for example, has established a national park that encompasses the central core of the country, covered in virgin rainforest and teeming with wildlife. Bolivia has set aside massive parks in areas with high biodiversity and unusual types of forests. Brazil, with the help of conservationists from around the world, is now working to save the last 8 percent of its Atlantic Forest in the southeast. Several countries in southern Africa are establishing international parks that greatly enlarge protected areas and allow migratory species, such as African Elephants and other ungulates, to move freely across borders. Corridors for wildlife to move from one area to another are also being established in the Americas. These prevent isolation of small populations of animals that would likely dwindle to extinction. Education is key to the future of preserving biodiversity, which is vital in maintaining the planet's ecological stability. Studies on this and related subjects are now being taught in an increasing number of high schools and colleges so that future generations will not squander the planet's true wealth, its natural heritage. Appreciation of the sheer beauty of the natural world and its wealth of species is an important facet of this project.
o Biodiversity study. Organize a group of students or interested persons to conduct biodiversity studies in your area. Ecosystems should range from low to high diversity. To study forest diversity, for example, you might select: (1) a small city park; (2) a suburban back yard or tree farm, and 3. a woodland, preferably old-growth. To study aquatic ecosystems, you might select: (1) a city creek or river; (2) a suburban pond, and (3) a sizeable natural wetland. The complexity of the project will depend on the experts available for identifying and recording species. The object will be to list as many species as possible from each area and provide a general description of the habitat. If there are rare, threatened or endangered species in any of the areas, these should be described and, if seen, carefully noted. Invite employees of the state's Natural Heritage Program to help in selection of sites and, if possible, accompany the group. A biodiversity day in the Boston area attracted many scientists, including botanists, ornithologists, herpetologists and mammalogists, who educated interested members of the public at various sites. Experts in birds do not have to be ornithologists but can be proficient bird-watchers, knowledgeable in bird song as well as sight identification. If the field trip is taken during bird migration, note which species breed in the area and which are migrating through. Mammals, reptiles, amphibians and fish (if in an aquatic environment) are less readily seen, and specialists in the latter animals might demonstrate methods of live-trapping or locating these animals by turning over rocks or netting. The identification of trees and plants, including ferns, mosses and lichens, will provide basic information about the habitat. If experts in some or all of these fields are available, or the team leaders are able to provide basic information, the group can be divided into subgroups, each of which will choose a type of life form, such as plants, invertebrates, birds or mammals. Once back in the classroom or environmental center, the various groups can meet and provide lists of the species they have seen in each area. Any rare, endemic or endangered species will be singled out and described in detail. This one-day project will not provide a complete picture of the biodiversity of an area but can give a general picture that is valuable. The effects that development has on nature and the need to protect wilderness and natural areas will become apparent through such a study. In general, biological diversity increases the farther one gets from large cities and suburban areas. Keep in mind, however, that some extremely rare species, especially plants and insects, have managed to survive in small pockets of wild habitat in unexpected places. Weedy growth next to railroads, for example, has been found to harbor many rare plants and insects. Such areas, never cleared for development, have remained natural. Open space, even with low biological diversity, is preferable to asphalt, and students may contribute ideas on making city parks and suburban backyards more diverse by planting trees and shrubs and allowing brushy areas to grow. More advanced students can participate in the CD-ROM biodiversity study listed below (see Wilson and Perlman 1999).
o Bird feeding. Another project involves appreciation of biodiversity with the potential for making a contribution to ornithology. Backyard bird feeders can provide an eye-opening education in biodiversity that is also extremely enjoyable. Bird feeders attract many common seed-eating birds. Adding suet and fruit can bring woodpeckers, orioles and other fruit-eating birds. The number of species that come to bird feeders is related to the habitat and surrounding area. Feeders in remote habitats or located on bird migratory flyways will attract more species than those placed in the city, which are likely to attract pigeons, sparrows and starlings, all European in origin. Sometimes, a rare species comes to the bird feeder to feed or is attracted as a predator on the birds. Bird feeders can provide important data on bird diversity and population trends. Cornell's Laboratory of Ornithology (159 Sapsucker Woods Road, Ithaca, NY 14850-1999 (Tel: 607-254-2473) conducts a program that enrolls volunteers to keep track of the birds that visit their feeders. By providing a wide variety of seed and other food, one can learn much about diets, how the birds feed, their behavior and plumage changes throughout the year. Books about bird feeding are sold in most book stores, and local chapters of the National Audubon Society provide information on feeders and feed. Television advice is given by Don and Lillian Stokes in their PBS series.
o Bird-watching. Bird-watching trips are important in learning about the majority of species that do not come to bird feeders or live in suburban backyards. Insect-eaters, such as warblers, flycatchers, vireos and other songbirds, can be seen only on migration or in their natural environments. During migration, especially in the spring, the beauty of these colorful birds, called "living jewels" by many naturalists, can be appreciated by using binoculars. Excursions to various habitats to see birds will also teach the diversity of environments, threats to them, and which types harbor the greatest diversity of birds. Local bird clubs, National Audubon Society chapters and naturalist clubs are sources of information on the best birding spots and times of year when one is likely to see the greatest number of birds. Many of these organizations conduct birding trips, both in the United States and in foreign countries. Declines in avian diversity and in population numbers will become evident after participation in several of these trips. Sources of information on such trends include trip guides who have been conducting tours or breeding bird surveys of the US Fish and Wildlife Service or the National Audubon Society over a period of years in the same habitat. Ask them for information on species that have declined or disappeared altogether as a result of environmental changes, pollution or other causes. Note the species of birds seen on the trip and find out from the guide or other authority, such as the US Fish and Wildlife Service or National Audubon Society, whether these species have declined over recent years. For example, shorebirds seen on coastlines or in the Mississippi River region have suffered dramatic losses of up to 90 percent in some species over the past 30 years. The causes are diverse, from overfishing of food sources, disturbance of beach nesting areas, loss of habitat in wintering or nesting grounds to killing on their wintering grounds. On the list of species seen, note population trends and their causes in the area visited.
o Worldwide perspective. Learning about biodiversity from a worldwide perspective is key to understanding the subject. Dr. Edward O. Wilson of Harvard University coined the word "biodiversity" in the 1988 book of that title that he edited. His other book on the subject is also a primary resource. Both give overviews of the world's wealth of species and risks to them. Another important basic reference, Conserving Biological Diversity, by Jeff McNeely and other authors, is a 1990 overview of the problem, with key species and regions described. This leads to Hotspots, written a decade later in 2000 by Dr. R.A. Mittermeier and others. This book identifies hotspots as the world's most endangered high-biodiversity areas and discusses each in terms of geography; habitat; which species are native, especially those that are found only that in particular area (endemic species); statistical biodiversity for each area; threats to the area; and what is being done to conserve them. Clive Ponting's A Green History of the World helps explain why past civilizations have died out as a result of ignorance and overexploitation of their environment and the native wildlife upon which they depended. Michael J. Novacek of the American Museum of Natural History edited a 2001 book, The Biodiversity Crisis. Losing What Counts, a collection of essays by prominent scientists and conservationists who discuss the increasing rate of extinctions and give case history examples of areas at risk and what strategies are working to help protect them. The other references listed below provide additional information.
- Write an essay on the problem of the loss of biodiversity, emphasizing the reasons why it is important to the future of human society, as well as for the sake of conservation.
- List ways that consumers in the United States who buy tropical hardwoods and other goods, use large amounts of non-renewable energy and produce greenhouse gases, affect the loss of biodiversity.
- Choose a country or area that has high biodiversity, such as Colombia, Madagascar or Indonesia, and describe the geography, climate, type(s) of biological diversity, threats, unique species of plants and animals, conservation programs, and whether they are successful. Calculate the losses of species should the present rate of deforestation or other destruction continue, using references such as Hotspots and Threatened Birds of the World.
o Species in danger. Learning about threatened plants, birds, mammals and other species will provide in-depth knowledge of what is at stake. Threatened Birds of the World examines the 1,100 species whose future survival is in danger. This book illustrates each species with range maps, status and other background information. Many of these birds are illustrated in The Life of Birds, a book by David Attenborough, and in a 10-hour film series based on it seen on PBS. The Video section describes other films about threatened species. Other threatened animals and plants surveyed by the 2000 IUCN Red List of Threatened Species are not described in depth by the International Union for the Conservation of Nature and Natural Resources (IUCN), which sponsors this list. The IUCN no longer publishes "Red Data Books," which gave background information on each species. The Internet site (www.redlist.org) provides some information, such as distribution and basic status category, but few listings give causes of the status and other related data. Such information gaps are filled in part by publications such as Walker's Mammals of the World, a two-volume, in-depth examination of mammals by Dr. Ronald Nowak, regularly updated and last issued in 1999. The IUCN Species Survival Commission sponsors many individual specialist groups that gather information on elephants, rhinos, whales, primates and many other categories. These groups issue newsletters and have websites. (Contact the SSC Red List Programme Officer, 219c Huntingdon Road, Cambridge CB3 0DL, UK; e-mail email@example.com). Select a group of species, such as salamanders, frogs or orchids, and describe their general status. How many species are threatened? What are the general causes? What areas of the world do they inhabit? What will be the effect on other animals or plants in their ecosystems should they disappear? What should be done to preserve them?
Books and Publications