Debt for nature swap pros and cons

In 1996, a consortium of research institutes, including theSmithsonian Institution, received funding for a researchproject in the tropical rain forest of Nigeria and Cameroon. The researchers studied the local abundance, distribution, and life cycles of trees and shrubs with medicinal properties in a large segment of forest in Cameroon and in several smaller plots in Nigeria. Researchers searched for beneficial drugs by examin- ing traditional medicines used by local villagers and by a mass screening of trees and shrubs. This project, funded by the U.S. Agency for International Development and several other U.S. government agencies, was an attempt to help develop alter- natives to deforestation. It is believed that cultivation of me- dicinal trees could provide an important source of income to

Preserving Biological Diversity

Biodiversity: Signs of Decline Causes of Extinction and the Decline in Biodiversity Why Protect Biodiversity? How to Save Endangered Species and Protect Biodiversity—A Sustainable Approach Spotlight on Sustainable Development 11-1: Predator Friendly Wool and Wolf Country Beef: You Must Have Read the Label Wrong Spotlight on Sustainable Development 11-2: Debt-for-Nature Swaps Point/Counterpoint 11-1: Preserving Wildlife, Usurping Private Property Rights? Point/Counterpoint 11-2: Controversy Over Wolf Reintroduction

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11.3

11.2

11.1

CHAPTER OUTLINE

CHAPTER 11

The worst sin toward our fellow creatures is not to hate them, but to be indifferent to them.

—George Bernard Shaw

194

CRITICAL THINKING

Exercise You own a guest ranch in western Colorado. Your ranch attracts people from all over the world who come to ride horses and view the abundant wildlife such as deer, elk, eagles, hawks, and an occasional black bear. You also raise sheep to supplement your family’s in- come. One day, a neighboring rancher calls on you to ask for your help in killing coyotes, which he says are killing off his sheep and costing him lots of money. What he wants is permission to spread chunks of meat, contain- ing a lethal poison called Compound 1080 on your property. What he is proposing is not le- gal, he freely admits, but it is done from time to time in remote parts of the West. He and other ranchers who want to control coyotes extract the poison from sheep collars—devices placed around the necks of sheep to selec- tively kill coyotes that attack them. Sheep collars are legal. Your neighbor will get the poison and even spread the scraps of meat on your property if you give him permission. He says it will also help protect your sheep herd.

What concerns would you have about this proposal? Make a list of questions you will need to answer before deciding whether to join your neighbor. What critical thinking rules will you use?

local communities. The field work, which ended in 2004, yielded numerous natural chemical com- pounds that could some day be used to treat tropi- cal diseases, mental disorders, and chronic diseases.

This project is one of many efforts designed to save forests and the species that live within them. It is part of an effort to protect the natural environ- ment and provide for the economic needs of peo- ple. As such, it is an example of the new philosophy of sustainable development.

This chapter examines biodiversity—the rich biological world—and new ways of protecting the planet’s wealth of wild species. In the following pages, you will examine the causes of extinction and the countless benefits of plants and wildlife to human societies to help you fully understand the importance of saving species.

Biodiversity: Signs of Decline By some estimates, as many as 500 million kinds of plants, animals, and microorganisms have made this planet home since the beginning of time. Today, scientists estimate that the world contains between 10 and 30 million species. Some put the estimate higher, up to 80 million. Only 1.9 million have been identified and named. Thus, 420 to 490 million species have become extinct over a period of 3.5 billion years.

This tells us that extinction is an evolutionary fact of life. Scientists refer to this as natural extinction. The natural oc- currence of extinction is viewed by many as a justification for plant and animal extinctions occurring today as a result of human activities, known as accelerated extinction. Why not?

Natural extinction differs markedly from accelerated extinction for at least two important reasons. First, natural extinction represents a kind of evolutionary passing. That is to say, many millions of species have become extinct, but they did not disappear. They evolved into new species (FIG- URE 11-1). Their kind may have vanished, but they gave rise to new species. Today, they are represented by their descen- dants. Modern extinctions, on the other hand, eliminate species entirely. They represent a dead end in evolution.

Second, the rate of extinction varies considerably. Even though some species did vanish in mass extinctions because of severe climatic changes or for other reasons, the rate of nat- ural extinction—about one species every 1,000 years—is slow compared with today’s accelerated extinction. Although no one can tell exactly how many species become extinct to- day, estimates based on loss of habitat and species diversity within these ecosystems suggest that it may be as many as 100 to 140 species every day or 36,500 to 50,000 per year. Harvard biologist E. O. Wilson thinks the number may be higher. As a result, many believe that we have entered into an era of extinction unparalleled in the history of the Earth. (For more on the acceleration of extinction and the impor- tance of species, see Point/Counterpoint 4-1.)

Today, thousands of species are endangered or threatened. An endangered species is one that is in imminent danger of becoming extinct. A threatened species is one that is still abundant in its natural range but, because its numbers are declining, is likely to become extinct in time. Without con- certed efforts to protect them, many threatened species will become extinct. How serious is the problem? Today, three- fourths of the world’s bird species are declining in number or threatened with extinction. Moreover, more than two- thirds of the world’s 150 species of primates are threatened. Today, approximately 8,725 species of plants are threatened or endangered—2 of every 100 plant species on Earth accord- ing to the International Union for the Conservation of Na- ture. In the United States, approximately 1,372 species of plants and animals, according to the U.S. Fish and Wildlife Service, are threatened or in danger of extinction.

Scientists around the world are disturbed by an alarm- ing disappearance of amphibians. Many species of frogs, toads, and salamanders are either experiencing steep de- clines in population size or have vanished. Amphibians are

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196 PART IV. Resource Issues: Solutions for a Sustainable Society

disappearing from a wide variety of habitats—from the jun- gles of Brazil to the suburbs of New York City. The cause is still unknown, but most scientists believe that the decline is the result of a wide range of factors including habitat loss; environmental pollution, such as pesticides; exposure to ultraviolet radiation due to ozone depletion; disease; para- sites; global warming; and others.

Unless we curb population growth, reduce pollution and habitat destruction, and manage our resources better, vast expanses of forests, wetlands, and grasslands will vanish

over your lifetime. Millions of species may vanish as a result. The impact of habitat destruction and mass extinction will be felt worldwide.

KEY CONCEPTS Many species of plants and animals face extinction today as a result of human activities. Although extinction has occurred since the dawn of time, modern extinctions are occurring at a rate much faster than is biologically sustainable.

3 million years ago

7 million years ago

25 million years ago

40 million years ago

60 million years ago Eohippus

Miohippus

Merychippus

Pliohippus

Equus

Foreleg

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P le

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P lio

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M io

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FIGURE 11-1 Gone but not forgotten. This drawing illustrates the stages in the evolutionary history of the horse. All dis- tinct species are extinct except for the mod- ern horse. Like other species, horses evolved through intermediate stages that no longer exist.

CHAPTER 11: Preserving Biological Diversity 197

Causes of Extinction and the Decline in Biodiversity

Plant and animal extinction, like many other environmen- tal problems, results from many factors. This section exam- ines the two most important factors today: habitat alteration and commercial hunting/harvesting. It also examines other important factors, including (1) the introduction of alien and domesticated species, (2) pest and predator control, (3) the collection of animals for pets and research, (4) pol- lution, (5) ecological factors, and (6) the loss of keystone species.

KEY CONCEPTS

Physical Alteration of Habitat We humans have always altered the environment to meet our needs. Virtually every activity we undertake changes the bi- otic and abiotic conditions of the environment and, hence, the biological communities of aquatic and terrestrial ecosys- tems (Chapter 6). Every product we buy comes with an en- vironmental price tag. Extraction of the raw materials and production of finished products, even the transportation to stores or our homes, for example, causes damage. Some of the most dramatic environmental changes come from activ- ities such as food production, timber harvesting, mining, road building, the manufacture and operation of automobiles, and the construction and maintenance of homes.

In recent years, even illegal immigration has taken a toll on wildlife and its habitat. Along the United States–Mexico border, thousands of illegal immigrants and law enforce- ment officials sent to curb this activity, have caused consid- erable damage to sensitive desert wilderness areas. One area that has been hard hit is the Cabeza Prieta National Wildlife Refuge in southwestern Arizona, a vast wilderness area that is home to many species including several endangered species. Mountains of trash and physical damage to the environment are causing concern to wildlife officials. Drug smugglers have created roads through these wilderness areas and more than 1,300 miles of foot paths. Parts of wilderness and wildlife refuge fenced off to protect visitors from illegal activities are now being overgrazed by cattle from Mexican farmers.

Human activities tend to fragment the habitat of plants and animals. Human settlements, for example, become islands of human activity in the natural environment. As the human population grows, however, and as roads, highways, farms, and buildings increase in number, the pattern changes: All that is left are a few islands of natural habitat in the human-dominated landscape (FIGURE 11-2). As the natural habitat fragments, species diversity declines.

Habitat alteration ranges from moderate to extreme and ranks as the most significant factor in the extinction of plants and animals the world over. It is no surprise to find that those

Many factors contribute to the loss of species, but the two most important are the destruction and alteration of habitat and commercial harvesting.

11.2

areas of the world that are at risk are regions of the most in- tense human activity.

Nowhere is the loss of habitat more pronounced than in the tropical rain forests. Tropical forests house at least half of the Earth’s species, perhaps more. Rain forests once cov- ered 14% of the Earth’s land surface. Over half of them have been cut down so they cover only 6% today. Countless species have perished as a result. At the current rate of destruction, the remaining rain forests could be gone by mid-century. (Chapter 12 discusses tropical rain forests in more detail.)

Coral reefs, wetlands, and estuaries (the mouths of rivers) are other critical habitats already greatly reduced and rapidly declining because of human development. Wetlands and estuaries, for example, are the home of many species but are also highly prized by humans for development. Dam- age to wetlands has been particularly severe in the industrial nations. New Zealand and Australia, for example, have lost more than 90% of their wetlands and countless species that lived in them. India, Pakistan, and Thailand have lost at least 75% of their mangrove swamps, a type of coastal wetland. Their ongoing destruction threatens the future of fish and waterfowl throughout the world. (For more on wetland destruction, see Chapter 13.)

Another ecosystem that has experienced serious losses is the tallgrass prairie of North America, which today is vir- tually nonexistent. Temperate rain forests, such as those in the Pacific Northwest, have also been subjected to in- tense harvesting. Worldwide, more than 56% of the tem- perate rain forests have been logged or cleared. No more than 10% of the original old- growth temperate rain for- ests remain in the United States. Canadian temperate

FIGURE 11-2 Habitat fragmentation. Humans carve up the natu- ral landscape to make room for cities, towns, farms, and other uses.

GO GREEN

Watch what you buy. Everything we purchase comes from the Earth, often a forest or a field. The more we buy, the more land we take from wildlife. Conscien- tious consumerism helps reduce our impact on wildlife.

198 PART IV. Resource Issues: Solutions for a Sustainable Society

rain forests have also been heavily cut. One of the many vic- tims of this loss is a bird known as the marbled murrelet. The murrelet feeds on schooling fish that congregate near the shores of Canada, but nests on moss-covered branches of the temperate rain forest within 30 kilometers (18 miles) of the shore. Logging of old growth forests in British Colum- bia has dramatically reduced the habitat of this bird, caus- ing equally dramatic declines in its numbers.

KEY CONCEPTS

Commercial Hunting and Harvesting Humans have hunted and killed animals throughout his- tory to provide food, fur, and other products. Several differ- ent types of hunting occur today. Sport hunting occurs for enjoyment and is generally well regulated. In fact, in many cases sport hunting benefits wild populations by helping to control numbers—so that they remain within the carrying capacity of the environment.

Another form of hunting is subsistence hunting, killing animals to provide food for indigenous people such as those who live in the tropical rain forests. Generally, such activi- ties are carried out on a sustainable level and do not pose a threat to animals, although there are notable exceptions.

The third form of hunting is commercial hunting, or har- vesting. This consists of large-scale efforts, such as the whale hunting of years past, and smaller operations, such as hunt- ing African rhinos for their horns. Smaller operations may be legal or, in some cases, illegal.

Whale hunting is one of the most familiar examples of commercial hunting. In the 1700s and 1800s, commercial whalers hunted one species after another to the brink of extinction to provide oil, meat, and other products. The result has been a severe reduction in whale populations (Table 11-1). Thanks to efforts by the International Whal- ing Commission, commercial whaling has been greatly re- duced. In its place is a new industry: whale watching, with annual revenues that exceed those of the commercial whal- ing industry itself.

Large-scale commercial hunting also doomed the pas- senger pigeon and greatly reduced the size of the bison herds of North America. The world’s fisheries (fishing grounds) have also been heavily harvested for commercial gain, and many important fisheries have been eliminated. Overharvesting continues today in many of the world’s remaining fisheries.

Commercial hunting may also occur illegally, on a much smaller scale. Illegal hunting is called poaching. Today, poachers continue to slaughter elephants, rhinos, tigers, and a variety of other endangered species because the economic benefits outweigh the risks of small fines or light jail sen- tences. A Bengal tiger coat, for example, sells for $100,000

Virtually all human activities alter the environment, changing the biotic and abiotic conditions and fragmenting habitat. Habi- tat alteration is the number one cause of species extinction. The most dramatic changes occur in biologically rich areas: tropical rain forests, wetlands, estuaries, and coral reefs.

in Japan. Poaching of ivory from tusks caused the near demise of African elephants, from an estimated 2.5 million in 1970 to an estimated 300,000 to 600,000 today according to the World Wildlife Foundation.

KEY CONCEPTS

The Introduction of Foreign Species Foreign, or alien, species introduced accidentally or intention- ally into new territories often do well in their new homes be- cause conditions may be highly favorable to their growth and reproduction. One reason for this is that these species may face little environmental resistance—for example, there may be no natural predators to hold their populations in check—in their new home. As their populations expand, alien species often outcompete and eliminate native species. The English spar- row is an example. Deliberately introduced into this country in the 1850s, the sparrow quickly spread throughout the con- tinent. It now competes for nesting sites and food once used by bluebirds, wrens, and swallows. The starling is another in- tentional import from England that has had a similar effect on native North American bird species. The barred owl of North America is yet another example. This native species has spread across the continent, some scientists think, hopscotch- ing from one patch of trees to another on the Great Plains, which was once a vast sea of grass that blocked the westward movement of the owl. It is now a resident of the forests of the Pacific Northwest. The barred owl harasses and preys on spotted owls and takes over their nesting sites. It may even interbreed and could further threaten this species, which is suffering because of the loss of vital old growth habitat.

Commercial hunting and harvesting of wild species have oc- curred for centuries and represent the second largest threat to the world’s animal species. This includes past activities, such as whale hunting, and present activities, such as commercial fish harvesting and poaching of endangered species.

Table 11-1 Whale Populations—Then and Now

Number Before Current Species Commercial Whaling Estimate

Blue 200,000 4,300 Bowhead 54,680 10,500 Fin 450,000 33,200 Gray 15,000–20,000 26,300 Humpback 119,000 63,600 Minke 250,000 761,000 Right 50,000 7,800 Sei (includes Bryde’s) 108,000 38,700 Sperm 1,377,000 360,000

Source: International Whaling Commission

CHAPTER 11: Preserving Biological Diversity 199

Another introduced species that’s raising havoc in North America is the grass carp, a native of China. Grass carp breed prolifically and are spreading through the rivers, squeezing out native species (FIGURE 11-3).

Alien plants and animals have taken their toll on native species of Canada, too. European starlings have displaced many species. Raccoons that were released on Queen Char- lotte Islands to provide additional income for local trappers have caused significant decreases in a type of sea bird known as an alcid. These burrow-nesting birds form huge vulnera- ble colonies. Raccoons raid the nests for food.

Nonnative plants also outcompete native species. Scotch broom, purple loosestrife, and crested wheatgrass have all been introduced into Canada and now compete aggressively with na- tive species, sometimes wiping them out altogether. Today, 23% of Canada’s wild plants are nonnative species. Islands are especially vulnerable to new species. In Hawaii, for example, 90% of all bird species have been wiped out by human inhab- itants and by organisms (such as rats) introduced by humans.

Alien species often do well in warm climates such as Florida. In fact, Florida is a showcase of alien species gone wild. Australian pines, for example, were introduced as or- namentals and have spread rapidly along coastal beaches and canals. Their shallow roots are so dense that they destroy sandy beaches, where many sea turtles lay their eggs. Worst of all is a species called the punk tree, which grows in swamps, creating a dense tangle of vegetation impassable to many animal species.

The Great Lakes of North America have also been sub- ject to numerous alien invasions, often with devastating eco- nomic and ecological consequences. The latest are the zebra mussel and fishook water fleas, both accidentally introduced by ships carrying cargo from Europe. The zebra mussel was described in Chapter 6. The fishook water flea feeds on phyto- plankton, the main food source of small fish. Besides posing

a threat to fisheries, the flea also has become a nuisance to commercial and sports fishers, clogging nets and lines. It is spreading rapidly throughout the Great Lakes and into sur- rounding waterways, just like the zebra mussel.

The alien invasion is nothing to take lightly. In the United States, a recent study that took 200 scientists 4 years to prepare estimates that 6,500 alien species of plants, ani- mals, insects and arachnids (spiders), and disease organ- isms have gained a foothold in the United States. They have caused 315 native species to become endangered or threat- ened. Although no one knows for sure how much damage alien species cause, one study by researchers at Cornell Uni- versity suggests that the damage in the United States caused by alien plants and animals may be over $120 billion per year! The main problems are predation on native species and habitat destruction.

KEY CONCEPTS

Pest and Predator Control Well-intentioned efforts to control species considered to be pests also affect wild populations of plants and animals, and they contribute to the steady decline in biodiversity on Earth. DDT and other pesticides, for example, have taken a huge toll on American wildlife (Chapter 22). The peregrine falcon had disappeared in the eastern United States by the 1960s as a result of DDT. This pesticide caused eggshell thinning, which made eggs fragile and susceptible to breakage. The en- tire population of falcons east of the Mississippi River was wiped out and dramatic declines occurred in the West, too. Eagles and brown pelicans met a similar fate. Even the Cali- fornia condor, a massive vulture, suffered from eggshell thin- ning. Especially harmful to migratory birds that spend their summer in North America are those pesticides (such as DDT and related compounds) that have been banned in the United States but are still used in Latin America.

Studies suggest that nonylphenols, a nonactive ingredi- ent of some pesticides, may have a deleterious effect on salmon. This near-ubiquitous water pollutant, also found in detergents, cosmetics, and plastics, enters waterways. In the Pacific Northwest, salmon migrating to the sea that are exposed to minute quantities of this chemical perish when exposed to salt water. Researchers believe that nonylphe- nols affect the endocrine system, making salmon unable to produce hormones needed to get rid of excess salt, an adap- tation vital to the transition to oceanic life.

Predator control, once the cornerstone of wildlife management, has had a profound impact on native species such as wolves, bears, and mountain lions in North Amer- ica. Killing off predators can also create severe habitat destruction, as the prey populations once controlled by these predators grow beyond the carrying capacity of their environment.

Plant and animal species introduced into new regions may thrive because of the favorable conditions and low environmental re- sistance. Therefore, they often outcompete and eliminate native species. Islands are especially vulnerable to foreign species.

FIGURE 11-3 Grass carp introduced from Asia reproduce prolifi- cally in many streams in the eastern U.S. and have become a major nuisance.

200 PART IV. Resource Issues: Solutions for a Sustainable Society

KEY CONCEPTS

The Collection of Animals and Plants for Human Enjoyment, Research, and Other Purposes Each year, millions of animals and plants are gathered from their native habitat throughout the world and exported to zoos, private collectors, pet shops, research institutes, and other places. The numbers are staggering. In 2010, for in- stance, nearly 333,000 live reptiles, and 153,000 reptile skins were legally imported into the United States. That same year, nearly 2,200 live birds were imported into the United States. Tens of thousands of birds are also imported by Canada and Great Britain. For each bird that makes it into someone’s home, though, 10 to 50 may die along the way (FIGURE 11-4) Many perish after they are taken home, too.

Scientists throughout the world use a variety of wild caught primates such as monkeys for research on pressing medical problems such as AIDS. Taken from their home- land in Africa, as many as five chimpanzees die for every one that enters a laboratory. In 1975, the United States banned the importation of all primates for pets but allowed contin- ued importation for zoos and research. Partly as a result,

Chemical pesticides, sprayed on farms and other areas to con- trol insect pests, and predator control programs have had a pro- found impact on native species.

primate imports have dropped rapidly in the United States and elsewhere (FIGURE 11-5). Nonetheless, in 2009, the lat- est year for which data were available, the United States imported over 22,000 primates, down from 28,000 in 2006.

Some rare and endan- gered primates are still cap- tured and sent to the United States. Because research an- imals often do not breed in captivity and because they have a high mortality rate, continual replenishment

from wild populations is likely to continue. As noted earlier in the chapter, two-thirds of the world’s 150 species of pri- mates are threatened with extinction.

Plants are also popular imports. In 2010, 1.8 million live cacti (including some artificially propagated) were imported into the United States from 18 countries, up from 3.8 million in 2003. International trade in exotic flowers, especially those originating in the Mediterranean, is also a booming business and currently threatens many native plant species.

At home, collectors pillage the deserts in Texas and Ari- zona in search of salable cacti to adorn the lawns of cus- tomers. To reduce the ravaging impact of commercial cactus rustling, Arizona has made it illegal to remove 222 different plant species. With penalties up to $1,000 and jail sentences up to 1 year, Arizona has taken a small step to protect its native plants. With only two “cactus cops” to patrol the state, though, little progress can be made.

KEY CONCEPTS

Pollution Pollution plays an important role in the decrease in the planet’s biodiversity and is bound to play a larger role as the human population and economy expand. Today, pollution-caused

Millions of plants and animals are taken from the wild and im- ported into developed countries for zoos, private collections, pet shops, and research, contributing to the worldwide loss of species.

FIGURE 11-4 Nature for sale. In the developing countries, local residents sell birds and animals they catch in nearby forests to dealers who export them, sometimes illegally, to the industrial na- tions. Many animals die along the way.

Year

N um

be r

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rim at

es (

in th

ou sa

nd s) 140

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0 200019951990 2005 201019851980197519701965

FIGURE 11-5 Decline in the number of primates imported into the United States.

GO GREEN

Do not buy exotic pets such as birds or fish that come from the wild. Check the source very carefully to be sure that they are domestically raised.

CHAPTER 11: Preserving Biological Diversity 201

problems such as global warming, acid deposition, and ozone depletion are creating major ecological changes. Pollution could combine with other extinction forces described in this chapter to greatly increase the threat to biodiversity. For ex- ample, global warming caused by carbon dioxide pollution from the burning of fossil fuels combined with several other pollutants may be responsible for a massive die-off of the world’s coral reefs, already besieged by sediment from on- shore development, damage from ships, and chemical pollu- tants. Coral reefs contain an estimated 1 million species. By one estimate, 60% of the world’s 230,000 square miles of coral reef could be lost by around 2040 if threats continue.

Global warming caused in large part by human pollu- tants is also taking its toll on the polar bear, a species threat- ened already by numerous other factors, including chemical pollution, hunting, tourism, and oil drilling in its habitat. As Arctic Sea ice melts due to global warming, polar bears have difficulty accessing their food source: seals. Bears that are un- dernourished face difficulty surviving (FIGURE 11-6).

Pollution is also of concern on a local level. In the semi- arid farmland of California’s San Joaquin Valley, the heavy metal selenium—contained in waters draining from irri- gated farm fields into specially built evaporation ponds (FIGURE 11-7) in the Kesterson National Wildlife Refuge— has caused massive biological effects. In 1985, for example, biologists found physical abnormalities in 42% of the chicks of waterfowl and wading birds at Kesterson—compared with an expected deformity rate of 1%. Problems included chicks without eyes, beaks, wings, and legs. Many embryos died. Adult birds and many other animals were also affected— as were crayfish, snakes, raccoons, and muskrats, which once flourished in the rich biological community but now have vanished. As one journalist put it, “The Kesterson Refuge had become a place that killed the animals it was supposed to protect.” (In 1986, the evaporation ponds at Kesterson were filled with dirt.) Federal officials note sim- ilar problems in refuges in Utah, Wyoming, Texas, Nevada, Arizona, and other parts of California. In nonrefuge sites,