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Science and the EnvironmentC H A P T E R 1

1 Understanding OurEnvironment

2 The Environment andSociety

4 Chapter 1 Science and the Environment

PRE-READING ACTIVITY

BookletBefore youread this chap-ter, create the

FoldNote entitled “Booklet”described in the Reading andStudy Skills section of theAppendix. Label each page ofthe booklet with a main ideafrom the chapter. As youread the chapter, write whatyou learn about each main idea on the appropri-ate page of the booklet.

More than 2,700 m (9,000 ft)above sea level, a forest ecologistis studying biodiversity in a CostaRican rain forest. To ascend to thetreetops, he shoots an arrow over abranch and hauls himself up withthe attached rope.

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Section 1 Understanding Our Environment 5

When someone mentions the term environment, some peoplethink of a beautiful scene, such as a stream flowing through awilderness area or a rain forest canopy alive with bloomingflowers and howling monkeys. You might not think of yourbackyard or neighborhood as part of the environment. In fact,the environment is everything around us. It includes the naturalworld as well as things produced by humans. But the environ-ment is also more than what you can see—it is a complex webof relationships that connects us with the world we live in.

What Is Environmental Science?The students from Keene High School in Figure 1 are searchingthe Ashuelot River in New Hampshire for dwarf wedge mussels.The mussels, which were once abundant in the river, are now indanger of disappearing completely—and the students want toknow why. To find out more, the students test water samplesfrom different parts of the river and conduct experiments. Couldthe problem be that sewage is contaminating the water? Or couldfertilizer from a nearby lawn be causing algae in the river to growrapidly and use up the oxygen that the mussels need to survive?Another possible explanation might be that a small dam on theriver is disrupting the mussels’ reproduction.

The students’ efforts have been highly praised and widelyrecognized. Yet they hope for a more meaningful reward—thepreservation of an endangered species. The students’ work is justone example of a relatively new field— thestudy of the impact of humans on the environment.

environmental science,

Objectives� Define environmental science, and

compare environmental sciencewith ecology.

� List the five major fields of studythat contribute to environmentalscience.

� Describe the major environmentaleffects of hunter-gatherers, theagricultural revolution, and theIndustrial Revolution.

� Distinguish between renewableand nonrenewable resources.

� Classify environmental problemsinto three major categories.

Key Termsenvironmental scienceecologyagriculturenatural resourcepollutionbiodiversity

S E C T I O N 1

Understanding Our Environment

Figure 1 � These students arecounting the number of dwarfwedge mussels in part of theAshuelot River. They hope that thedata they collect will help preservethis endangered species.

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The Goals of Environmental Science One of the major goals ofenvironmental science is to understand and solve environmentalproblems. To accomplish this goal, environmental scientists studytwo main types of interactions between humans and the environ-ment. One area of study focuses on how we use naturalresources, such as water and plants. The other area of studyfocuses on how our actions alter our environment. To study theseinteractions, environmental scientists must gather and analyzeinformation from many different disciplines.

Many Fields of Study Environmental science is an interdiscipli-nary science, which means that it involves many fields of study.One important foundation of environmental science is ecology.

is the study of how living things interact with each otherand with their nonliving environment. For example, an ecologistmight study the relationship between bees and the plants thatbees pollinate. However, an environmental scientist might investi-gate how the nesting behavior of bees is influenced by humanactivities, such as suburban landscaping.

Many other sciences contribute to environmental science. Forexample, chemistry helps us understand the nature of pollutants.Geology helps us model how pollutants travel underground.Botany and zoology provide information to preserve species.Paleontology, the study of fossils, can help us understand howEarth’s climate has changed in the past. Using such informationabout the past can help us predict how future climate changescould affect life on Earth. Figure 2 shows a few examples of dis-ciplines that contribute to environmental science.

How is ecology related to environmental science?(See the Appendix for answers to Reading Checks.)■●✓ Reading Check

Ecology

6 Chapter 1

HistoryConnection to

Rachel Carson Alarmed by theincreasing levels of pesticides andother chemicals in the environ-ment, biologist Rachel Carsonpublished Silent Spring in 1962.Carson imagined a spring morn-ing that was silent because thebirds and frogs were dead afterbeing poisoned by pesticides.Carson’s carefully researchedbook was enthusiastically receivedby the public and was read bymany other scientists, as well aspolicy makers and politicians.However, many people in thechemical industry saw SilentSpring as a threat to their pesti-cide sales and launched a$250,000 campaign to discreditCarson. Carson’s research pre-vailed, although she died in1964—unaware that the bookshe had written was instrumentalin the birth of the modern envi-ronmental movement.

Figure 2 � Many Fields of Study

� This marine biologist (right) isstudying a marine mammal calleda manatee.

� This ornithologist (above) isstudying the nesting behavior ofseabirds called albatrosses.

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But studying the environment also involves studying humanpopulations, so environmental scientists may use information fromthe social sciences, which include economics, law, politics, andgeography. Social sciences can help us answer questions such as,How do cultural attitudes affect how people use the U.S. nationalpark system? or How does human migration from rural to urbanareas affect the local environment? Table 1 lists some of the majorfields of study that contribute to the study of environmental science.


Major Fields of Study That Contribute to Environmental Science

Geography is the study of the relationship between human populations and Earth’s features.Anthropology is the study of the interactions of the biological, cultural, geographical,and historical aspects of humankind.Sociology is the study of human population dynamics and statistics.

Social sciences arethe study of humanpopulations.

Biochemistry is the study of the chemistry of living things.Geochemistry, a branch of geology, is the study of the chemistry of materialssuch as rocks, soil, and water.

Chemistry is thestudy of chemicalsand their interactions.

Engineering is the science by which matter and energy are made useful tohumans in structures, machines, and products.

Physics is the study of matter and energy.

Geology is the study of the Earth’s surface, interior processes, and history.Paleontology is the study of fossils and ancient life.Climatology is the study of the Earth’s atmosphere and climate.Hydrology is the study of Earth’s water resources.

Earth science is thestudy of the Earth’snonliving systems andthe planet as a whole.

Zoology is the study of animals.Botany is the study of plants.Microbiology is the study of microorganisms.Ecology is the study of how organisms interact with their environment and each other.

Biology is the studyof living organisms.

Table 1 �

� This geologist is studying a volcano in Hawaii.

� This biologist is examining a plantthat was grown in a lab from just afew cells.

www.scilinks.orgTopic: Careers in

EnvironmentalScience

Code: HE80223

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Scientists as Citizens, Citizens as ScientistsGovernments, businesses, and cities recognize that studying ourenvironment is vital to maintaining a healthy and productive soci-ety. Thus, environmental scientists are often asked to share theirresearch with the world. Figure 3 shows scientists at a press con-ference that was held after a meeting on climate change.

Often, the observations of nonscientists are the first steptoward addressing an environmental problem. For example, middle-school students first noticed the appearance of deformedfrogs in Minnesota lakes. Similarly, the students at Dublin SciotoHigh School in Ohio, shown in Figure 3, study the habitat ofendangered box turtles every year. A habitat is a place where anorganism usually lives. The students want to find out how the tur-tles live and what factors affect their nesting and hibernation sitesin their habitat. The students track and map the turtles’ move-ments, measure atmospheric conditions, and analyze soil samples.These efforts matter, because the box turtle habitat is threatened.At the end of every year, the students present their findings to cityplanners, hoping to protect the most sensitive turtle habitats.


1. Describe the two main types of interactions that envi-ronmental scientists study. Give an example of each.

2. Describe the major fields of study that contribute toenvironmental science.

3. Explain why environmental science is an interdisci-plinary science.

CRITICAL THINKING4. Making Comparisons What is the difference

between environmental science and ecology?

5. Making Inferences Read the Ecofact. Propose asolution to prevent the environmental problems ofthe seaport of Troy described in the Ecofact.

READING SKILLS

S E C T I O N 1 Mid-Section Review

Figure 3 � Environmental Scienceand Public Life Scientists hold apress conference on climate change(above). Students (right) are studyingthe movements of box turtles.

EcofactThe Fall of Troy Environmentalproblems are nothing new. Nearly3,000 years ago, the Greek poetHomer wrote about the ancientseaport of Troy, which was locatedbeneath a wooded hillside. TheTrojans cut down all the trees onthe surrounding hills. Without treesto hold the soil in place, rainwashed the soil into the harbor.So much silt accumulated in theharbor that large ships could notenter and Troy’s economy collapsed.Today, the ruins of Troy are severalmiles from the sea.

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Our Environment Through TimeWherever humans have hunted, grown food, or settled,they have changed the environment. For example, theland where New York City now stands was once anarea where Native Americans hunted game andgathered food, as shown in Figure 4. The environ-mental change that has occurred on ManhattanIsland over the last 300 years is immense, yet thisperiod of time is just a “blink” in human history.

Hunter-Gatherers For most of human history,people were hunter-gatherers, or people who obtainfood by collecting plants and by hunting wild animalsor scavenging their remains. Early hunter-gatherergroups were small, and they migrated from place to placeas different types of food became available at different times of the year. Even today there are hunter-gatherer societies in theAmazon rain forests of South America and in New Guinea, asshown in Figure 5.

Hunter-gatherers affected their environment in many ways.For example, some Native American tribes hunted bison, whichlive in grasslands. The tribes set fires to burn the prairies and pre-vent the growth of trees. In this way, the tribes kept the prairiesas open grassland where they could hunt bison.

In North America, a combination of rapid climate changes andoverhunting by hunter-gatherers may have led to the disappearanceof some species of large mammals. These species include giantsloths, giant bison, mastodons, cave bears, and saber-toothed cats.Huge piles of bones have been found in places where hunter-gatherers drove thousands of animals into pits and killed them.

Name two ways that hunter-gatherers affected theirenvironment.■●✓ Reading Check


Figure 5 � This modern hunter-gatherer group lives in New Guinea,a tropical island off the north coast ofAustralia.

Figure 4 � Three hundred yearsago, Manhattan was a very differentplace. This painting shows an areawhere Native Americans hunted and fished.

ComparisonTable

Create the Graphic Organizerentitled “Comparison Table”described in the Appendix. Labelthe columns with “Hunter-Gatherers,” “The AgriculturalRevolution,” and “The IndustrialRevolution.” Label the rows with“Characteristics” and “Effects onthe Environment.” Then, fill in thetable with details about the char-acteristics and the effects on the environment of each historical period.

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The Agricultural Revolution Eventually many hunter-gatherergroups began to collect the seeds of the plants they gathered and todomesticate some of the animals in their environment.is the practice of growing, breeding, and caring for plants and ani-mals that are used for food, clothing, housing, transportation, andother purposes. The practice of agriculture started in many differ-ent parts of the world over 10,000 years ago. This change hadsuch a dramatic impact on human societies and their environmentthat it is often called the agricultural revolution.

The agricultural revolution allowed human populations to growat an unprecedented rate. An area of land can support up to 500times as many people by farming as it can by hunting and gathering.As populations grew, they began to concentrate in smaller areas.These changes placed increased pressure on local environments.

The agricultural revolution also changed the food we eat. Theplants we grow and eat today are descended from wild plants.During harvest season, farmers collected seeds from plants thatexhibited the qualities they desired. The seeds of plants with largekernels or sweet and nutritious flesh were planted and harvestedagain. Over the course of many generations, the domesticatedplants became very different from their wild ancestors. For exam-ple, the grass shown in Figure 6 may be related to the grass thatcorn was bred from.

As grasslands, forests, and wetlands were replaced with farm-land, habitats were destroyed. Slash-and-burn agriculture, shownin Figure 7, is one of the earliest ways that land was converted tofarmland. Replacing forest with farmland on a large scale cancause soil loss, floods, and water shortages. In addition, much ofthis converted land was farmed poorly and is no longer fertile. Thedestruction of farmland had far-reaching environmental effects. Forexample, the early civilizations of the Tigris-Euphrates River basincollapsed, in part, because the overworked soil became infertilethrough salt contamination.

Agriculture

10 Chapter 1

Figure 6 � This grass, called Eastern gama grass, is thought to be a relative of the modern corn plant.Native Americans may have selectivelybred a grass like this to produce corn.

Figure 7 � For thousands of yearshumans have burned forests to create fields for agriculture. In thisphoto, a rain forest in Thailand isbeing cleared for farming.

FIELD ACTIVITYFIELD ACTIVITY Germinating Corn Many peo-ple do not realize how easy it is togrow corn plants from unpoppedpopcorn kernels. This ancient grasswill sprout in a matter of days if itis watered frequently. Place a fewpopcorn kernels on a wet papertowel, and place the paper towelin a clear plastic cup so that thekernels are visible from the outside.Leave the cup on a windowsillfor several days and water it fre-quently. As your plant grows, see if you can observe any grasslikefeatures. Record your observationsin your EcoLog.

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The Industrial Revolution For almost 10,000 years the tools ofhuman societies were powered mainly by humans or animals.This pattern changed in the middle of the 1700s with theIndustrial Revolution, which involved a shift from energy sourcessuch as animal muscle and running water to fossil fuels, such ascoal and oil. The increased use of fossil fuels and machines, suchas the steam engines shown in Figure 8, changed society andgreatly increased the efficiency of agriculture, industry, and transportation.

During the Industrial Revolution, the large-scale productionof goods in factories became less expensive than the local pro-duction of goods. Machinery reduced the amount of land andhuman labor needed for farming. As fewer people grew theirown food, populations in urban areas steadily grew. Fossil fuelsand motorized vehicles allowed food and other goods to betransported cheaply across great distances.

Improving Quality of Life The Industrial Revolution introducedmany positive changes. Inventions such as the light bulb greatlyimproved our quality of life. Agricultural productivity increased,and sanitation, nutrition, and medical care vastly improved. Tech-nologies such as the telephone and the portable computer, shownin Figure 9, enabled people to work and communicate more easilyfrom any location. Yet with all of these advances, the IndustrialRevolution introduced many new environmental problems.

In the 1900s, modern societies began to use artificial sub-stances in place of raw animal and plant products. Plastics andmany other artificial materials have made life easier. However, wenow understand some of the environmental problems they pre-sent. Much of environmental science is concerned with the prob-lems associated with the Industrial Revolution.

Identify three ways that the Industrial Revolutionchanged society.■●✓ Reading Check


Figure 8 � During much of theIndustrial Revolution, few limits wereplaced on the air pollution caused byburning fossil fuels. Locomotives suchas these are powered by burning coal.

Figure 9 � The invention of com-puters has improved the ways thatpeople work, learn, communicate,and entertain themselves.

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Lake Washington: An EnvironmentalSuccess Story

Figure 10 � This photograph wastaken in 1968 by the crew of Apollo8. Photographs such as this helped people realize the uniqueness of theplanet we share.

Seattle is located on a narrow stripof land between two large bodies ofwater. To the west is the PugetSound, which is part of the PacificOcean, and to the east is Lake Wash-ington, which is a deep freshwaterlake. During the 1940s and early1950s, cities on the east side of LakeWashington built 11 sewer systemsthat emptied into the lake. Unlikeraw sewage, this sewage was treatedand was not a threat to humanhealth. So, people were surprised byresearch in 1955 showing that thetreated sewage was threatening theirlake. Scientists working in Dr. W. T.Edmondson’s lab at the University ofWashington found a bacterium,Oscillatoria rubescens, that had neverbeen seen in the lake before.

Dr. Edmondson knew that inseveral lakes in Europe, pollutionfrom sewage had been followed by

allowing it to build up in anenclosed lake.

Cities around the lake had towork together to connect theirsewage plants to large lines thatwould carry the treated sewage toPuget Sound. Because there was nolegal way for cities to connect plants

the appearance of O. rubescens. Ashort time after, the lakes deterio-rated severely and became cloudy,smelly, and unable to support fish.The scientists studying Lake Wash-ington realized that they were see-ing the beginning of this process.

About this same time, Seattleset up the Metropolitan ProblemsAdvisory Committee, chaired byJames Ellis. Dr. Edmondson wroteEllis a letter that explained whatcould be expected in the future ifaction was not taken. The best solu-tion to the problem seemed to beto pump the sewage around thelake and empty it deep into PugetSound. Although this solution mayseem like it would save one body ofwater by polluting another one, itwas actually a good choice. Dilutingthe sewage in Puget Sound is less ofan environmental problem than

Spaceship EarthEarth has been compared to a ship traveling through space,unable to dispose of waste or take on new supplies as it travels.Earth is essentially a closed system—the only thing that entersEarth’s atmosphere in large amounts is energy from the sun, andthe only thing that leaves in large amounts is heat. A closed sys-tem of this sort has potential problems. Some resources are lim-ited, and as the population grows, the resources will be used. In aclosed system, there is also the chance that we will producewastes more quickly than we can dispose of them.

Although the Earth can be thought of as a complete system, envi-ronmental problems can occur on different scales: local, regional, orglobal. For example, your community may be discussing where tobuild a new landfill, or local property owners may be arguing withenvironmentalists about the importance of a rare bird or insect. Thedrinking water in your region may be affected by a polluted riverhundreds of miles away. Other environmental problems are global.For example, ozone-depleting chemicals released in Brazil maydestroy the ozone layer that everyone on Earth depends on.

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� Lake Washington is now cleanenough for everyone to enjoy.

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World Population: 1600–2000

Figure 11 � The size of the humanpopulation in 2000 was more than10 times larger than it was just 400years ago.

at the time, Ellis successfully workedfor the passage of a bill in the statelegislature that set up committees tohandle projects of this kind. News-paper articles and letters to the edi-tor addressed the issue. Public forumsand discussion groups were also held.

The first sewage plant was con-nected in 1963. Today, the lake isclearer than it has been since scien-tists began their studies of the lakein the 1930s. The story of Lake

moving the sewage. Legislators andcivic leaders addressed the legalproblems. Volunteers, local media,and local activists provided publiceducation and pressed to get theproblem solved quickly. The clear,blue waters of Lake Washingtonstand as a monument to citizens’desires to live in a clean, healthyenvironment and to their ability towork together to make it happen.

CRITICAL THINKING

1. Analyzing Processes Explainhow each person and group playeda crucial role in the cleanup of LakeWashington.

2. Analyzing Relationships Howwas the scientists’ work similar tothe work of the Keene High Schoolstudents you read about in thissection?

Washington is an example of howenvironmental science and publicaction work together to solve envi-ronmental problems. Science wasessential to understanding a healthylake ecosystem, to documentingchanges that were beginning tocause problems, and to making pre-dictions about what would happenif changes were made or if nothingwas done. Engineers offered practi-cal solutions to the problem of

Population Growth: A Local Pressure One reason many environ-mental problems are so pressing today is that the agricultural rev-olution and the Industrial Revolution allowed the humanpopulation to grow much faster than it had ever grown before.The development of modern medicine and sanitation also helpedincrease the human population. As shown in Figure 11, thehuman population almost quadrupled during the 20th century.Producing enough food for such a large population has environ-mental consequences. In the past 50 years, nations have used vastamounts of resources to meet their need for food. Many of theenvironmental problems that affect us today, such as habitatdestruction and pesticide pollution, are the result of feeding theworld in the 20th century.

There are many different predictions of population growth forthe future. But most scientists think that the human populationwill almost double in the 21st century before it begins to stabi-lize. We can expect that the pressure on the environment willcontinue to increase as the human population and its need forfood and resources grows.

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What Are Our Main Environmental Problems?You may feel as though the world has an unlimited variety ofenvironmental problems. But we can generally group environ-mental problems into three categories: resource depletion, pollu-tion, or loss of biodiversity.

Resource Depletion Any natural material that is used byhumans is called a Natural resources can beclassified as renewable and nonrenewable as shown in Table 2. Arenewable resource is a resource that can be replaced relativelyquickly by natural processes. Fresh water, air, soil, trees, andcrops are all resources that can be renewed. Energy from the sunis also a renewable resource. A nonrenewable resource is aresource that forms at a much slower rate than the rate that it isconsumed. The most common nonrenewable resources are miner-als and fossil fuels. Once the supply of a nonrenewable resourceis used up, it may take millions of years to replenish it.

Resources are said to be depleted when a large fraction of theresource has been used up. Figure 12 shows a mine where copper,a nonrenewable resource, is removed from the Earth’s crust.Some renewable resources can also be depleted. For example, iftrees are harvested faster than they can grow naturally in an area,deforestation will result.

Pollution One effect of the Industrial Revolution is that societiesbegan to produce wastes faster than the wastes could be disposedof. These wastes accumulate in the environment and cause pollu-tion. is an undesired change in air, water, or soil thatadversely affects the health, survival, or activities of humans or

Pollution

natural resource.


Figure 12 � More than 12 milliontons of copper have been minedfrom the Bingham mine in Utah.Once all of the copper that can beprofitably extracted is used up, thecopper in this mine will be depleted.

Renewable and Nonrenewable Resources

Renewable Nonrenewable

energy from the sun

water

wood

soil

air

metals such asiron, aluminum,and copper

nonmetallic ma-terials such as salt,sand, and clay

fossil fuels

Table 2 �

QuickLABClassifying ResourcesProcedure1. Create a table similar to Table 2.2. Choose five objects in your

classroom, such as a pencil, anotebook, or a chair.

3. Observe your objects closely,and list the resources that com-prise them. For example, a pen-cil is made of wood, graphite,paint, aluminum, rubber, andpumice.

4. Classify the resources you haveobserved as nonrenewable orrenewable.

Analysis1. What percentage of the resources

you observed are renewable?What percentage of theresources are nonrenewable?

2. Hypothesize the origin of threeof the resources you observed.If time permits, research the ori-gin of the resources you choseto find out if you were correct.

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other organisms. Human activities produce a greatdeal of pollution. Air pollution in Mexico City, asshown in Figure 13, is dangerously high, mostlybecause of car exhaust and industrial pollutants.

There are two main types of pollutants. Biode-gradable pollutants are pollutants that can be brokendown by natural processes. They include materialssuch as human sewage and food wastes. Degradablepollutants are a problem when they accumulate fasterthan they can be broken down. Pollutants that cannotbe broken down by natural processes, such as mer-cury, lead, and some types of plastic, are called non-degradable pollutants. Because nondegradablepollutants do not break down easily, they can buildup to dangerous levels in the environment.

Loss of Biodiversity The term refers to the num-ber and variety of species that live in an area. Earth has beenhome to hundreds of millions of species. Yet only a fraction ofthose species are alive today—the others are extinct. Extinction isa natural process, and several large-scale extinctions, or massextinctions, have occurred throughout Earth’s history. For exam-ple, at the end of the Permian period, 250 million years ago, asmuch as 95 percent of all species became extinct. So why shouldwe be concerned about the modern extinction of an individualspecies such as the Tasmanian tiger shown in Figure 14?

The organisms that share the world with us can be considerednatural resources. We depend on other organisms for food, forthe oxygen we breathe, and for many other things. A species thatis extinct is gone forever, so a species can be considered a nonre-newable resource. We have only limited information about howmodern extinction rates compare with those of other periods inEarth’s history. But many scientists think that if current rates ofextinction continue, it may cause problems for human popula-tions in the future. Many people also argue that all species havepotential economic, ecological, scientific, aesthetic, and recrea-tional value, so it is important to preserve them.

biodiversity


1. Explain how hunter-gatherers affected the environ-ment in which they lived.

2. Describe the major environmental effects of theagricultural revolution and the Industrial Revolution.

3. Explain how environmental problems can be local,regional, or global. Give one example of each.

4. Identify an example of a biodegradable pollutant.

CRITICAL THINKING5. Analyzing Relationships How did the Industrial

Revolution affect human population growth?

6. Making Inferences Fossil fuels are said to be non-renewable resources, yet they are produced by theEarth over millions of years. By what time frame arethey considered nonrenewable? Write a paragraphthat explains your answer. WRITING SKILLS

S E C T I O N 1 Review

Figure 14 � The Tasmanian tiger,native to an island near Australia, wasdeclared extinct in 1986.

Figure 13 � The problem of air pol-lution in Mexico City is compoundedbecause the city is located in a valleythat traps air pollutants.

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When we think about environmental problems and how to solvethem, we have to consider human societies, how they act, andwhy they do what they do. One way to think about society andthe environment is to consider how a society uses commonresources. A neighborhood park, for example, is a commonresource that people share. On a larger scale, the open ocean isnot owned by any nation, yet people from many countries use theocean for fishing and for transporting goods. How do we decidehow to share common resources? In 1968, ecologist GarrettHardin published an essay titled “The Tragedy of the Commons,”which addressed this question.

“The Tragedy of the Commons”In his essay, Hardin argued that the main difficulty in solvingenvironmental problems is the conflict between the short-terminterests of individuals and the long-term welfare of society. Toillustrate his point, Hardin used the example of the commons, asshown in Figure 15. Commons were areas of land that belongedto a whole village. Anyone could graze cows or sheep on thecommons. It was in the best short-term interest of an individualto put as many animals as possible on the commons. Individualsthought, If I don’t use this resource, someone else will.

However, if too many animals grazed on the commons, the animalsdestroyed the grass. Then everyone suffered because no one could raiseanimals on the commons. Commons were eventually replaced by closedfields owned by individuals. Owners were careful not to put too manyanimals on their land, because overgrazing meant that fewer animalscould be raised the next year. The point of Hardin’s essay is thatsomeone or some group has to take responsibility for maintaining aresource. If no one takes that responsibility, the resource can be overusedand become depleted.

Objectives� Describe “The Tragedy of the

Commons.”� Explain the law of supply and

demand.� List three differences between

developed and developing countries.

� Explain what sustainability is, anddescribe why it is a goal of envi-ronmental science.

Key Termslaw of supply and demandecological footprintsustainability

S E C T I O N 2

The Environment and Society


Figure 15 � Hardin observed thatwhen land was held in common(left), individuals tended to grazeas many animals as possible. Over-grazing led to the destruction ofthe land resources. When com-mons were replaced by enclosedfields owned by individuals (right),people tended to graze only thenumber of animals that the landcould support.

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Earth’s natural resources are our modern commons. Hardinthought that people would continue to deplete natural resources byacting in their own self-interest to the point of society’s collapse.But Hardin did not consider the social nature of humans. Humanslive in groups and depend on one another. In societies, we cansolve environmental problems by planning, organizing, consideringthe scientific evidence, and proposing a solution. The solution mayoverride the interests of individuals in the short term, but itimproves the environment for everyone in the long term.

Economics and the EnvironmentIn addition to social pressures, economic forces influence how weuse resources. Many of the topics you will explore later in thisbook are affected by economic considerations.

Supply and Demand One basic rule of economics is thewhich states that the greater the demand for

a limited supply of something, the more that thing is worth. Oneexample of this rule is shown in Figure 16, which illustrates therelationship between the production of oil and its price over aperiod of 20 years. Many environmental solutions have to takethe relationship between supply and demand into account. Forexample, if the supply of oil decreases, we have three choices: paythe higher price, use less oil, or find new sources of energy.

Costs and Benefits The cost of environmental solutions can behigh. To determine how much to spend to control air pollution, a community may perform a cost-benefit analysis. A cost-benefitanalysis balances the cost of the action against the benefits oneexpects from it. The results of a cost-benefit analysis often dependon who is doing the analysis. To an industry, the cost of pollutioncontrol may outweigh the benefits, but to a nearby community, thebenefits may be worth the high price. The cost of environmentalregulations is often passed on to the consumer or the taxpayer. The consumer then has a choice. He or she can either pay for the more expensive product that meets environmental regulationsor seek out a cheaper product that may not have the same environmental safeguards.

Risk Assessment One of the costs of any action is the risk of anundesirable outcome. Cost-benefit analysis involves risk assessment,which is one tool that helps us create cost-effective ways to protectour health and the environment. To come up with an effective solu-tion to an environmental problem, the public must perceive the riskaccurately. This does not always happen. In one study, people wereasked to assess the risk from various technologies. The public gen-erally ranked nuclear power as the riskiest technology on the list,whereas experts ranked it 20th—less risky than riding a bicycle.

Use an example to illustrate the law of supply anddemand.■●✓ Reading Check

supply and demand,law of

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World Oil Production

Co

st p

er b

arre

l (d

olla

rs)

Source: U.S. Department of Energy.

Figure 16 � Between 1980 and2000, the production and price of oil changed dramatically. Thisgraph shows how, in general, theprice of a barrel of oil increased asthe production decreased.

Section 2 The Environment and Society 17

MATHPRACTICEMarket EquilibriumIn economics, the point where supply and demand are in balance is known as marketequilibrium. In Figure 16, marketequilibrium for oil was reached in 1986. What was the cost of abarrel of oil in that year? Howmany barrels of oil were producedin that year? By how much did thecost of a barrel of oil decline from1981 to 1986?

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Developed and Developing CountriesThe decisions and actions of all people in the world affect ourenvironment. But the unequal distribution of wealth andresources around the world influences the environmental prob-lems that a society faces and the choices it can make. The UnitedNations classifies countries as either developed or developing.Developed countries have higher average incomes, slower popula-tion growth, diverse industrial economies, and stronger socialsupport systems. They include the United States, Canada, Japan,and the countries of Western Europe. Developing countries havelower average incomes, simple and agriculture-based economies,and rapid population growth. Developed and developing coun-tries have different consumption patterns, as shown in Figure 17,which affect the environment in different ways.

Population and Consumption Most environmental problems can be traced back to two rootcauses. First, the human population in some areas is growingtoo quickly for the local environment to support it. Second,people are using up, wasting, or polluting many naturalresources faster than they can be replaced or cleaned up.

Local Population Pressures When the population in an areagrows rapidly, there may not be enough natural resources foreveryone in the area to live a healthy, productive life. Often, aspeople struggle for survival in severely overpopulated regions,forests are stripped bare, topsoil is exhausted, and animals aredriven to extinction. Malnutrition, starvation, and disease can beconstant threats. Even though there are millions of people starv-ing in developing countries, the human population tends to growmost rapidly in these countries. Food production, education, andjob creation cannot keep pace with population growth, so eachperson gets fewer resources as time goes by. Of the 5.2 billionpeople in developing countries, fewer than half have access toenough food, safe drinking water, and proper sanitation.

18 Chapter 1

Figure 17 � A food market inPushkar, India is shown above.The food market shown belowis in Goleta, California, in theUnited States. How do thesetwo food markets show differingconsumption trends in Indiaand the U.S.?

GeofactMinerals of South Africa Theresources a country has are a resultof geologic processes. South Africa,for example, has some of the mostproductive mineral deposits in theworld. In fact, the country is nearlyself-sufficient in the mineralresources that are important tomodern industry. South Africa isthe world’s largest producer ofgold, platinum, and chromium.

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Figure 18 � An ecological footprintis a calculation of the amount of landand resources needed to support oneperson from a particular country. Theecological footprint of a person in adeveloped country is, on average,four times as large as the footprint ofa person in a developing country.

Table 3 �

Indicators of Development for the United States, Japan, Mexico, and Indonesia

Measurement U.S. Japan Mexico Indonesia

Health life expectancy in years 77 81 71.5 68

Population per year 0.8% 0.2% 1.7% 1.8%growth

Wealth gross national product per person $29,240 $32,350 $3,840 $640

Living space people per square mile 78 829 133 319

Energy use per person per year (millions of Btu) 351 168 59 18

Pollution carbon dioxide from fossil 20.4 9.3 3.5 2.2fuels per person per year (tons)

Waste garbage produced per person per year (kg) 720 400 300 43

Consumption Trends For many people in the wealthier part of theworld, life is better than ever before. Many environmental problemsare being addressed. In addition, the population has stabilized or isgrowing slowly. But to support this quality of life, developed coun-tries are using much more of Earth’s resources than developingcountries are. Developed nations use about 75 percent of theworld’s resources, even though they make up only about 20 percentof the world’s population. This rate of consumption creates morewaste and pollution per person than in developing countries, asshown in Table 3.

Ecological Footprints One way to express the differences in con-sumption between nations is as an ecological footprint, as shown inFigure 18. An shows the productive area ofEarth needed to support one person in a particular country. It esti-mates the land used for crops, grazing, forest products, and hous-ing. It also estimates the ocean area used to harvest seafood and theforest area needed to absorb the air pollution caused by fossil fuels.

ecological footprint

0

5

10

15

20

25

30

35

India Mexico BritainU.S.

Eco

log

ical

foo

tpri

nt

(acr

es)

19

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Environmental Science in ContextAs you have learned, environmental problems are complex.Simple solutions are rare, and they sometimes cause more damagethan the original problem did. To complicate matters, in recentyears, the environment has become a battleground for largerissues that affect human societies. For example, how do you bal-ance the rights of individuals and property owners with the needsof society as a whole? Or, when economic or political refugeesemigrate—legally or illegally—what can be done about the dev-astation they may cause to the local environment? How dohuman rights relate to the environment?

Critical Thinking and the Environment People on any side of anenvironmental issue may feel passionately about their cause, andthey can distort information and mislead people about the issues.Research done by environmental scientists is often used to makepolitical points or is misrepresented to support controversial view-points. In addition to the scientific data, the economic dimensionsof an environmental issue can be oversimplified. To further com-plicate things, the media often sensationalizes environmentalissues. So, as you make your own decisions about the environ-ment, it is essential that you use your critical-thinking skills.

Learning to think critically about what you see in news-papers, on TV, and on the Internet will help you make informeddecisions. As you explore environmental science further, youshould remember a few things. First, be prepared to listen tomany viewpoints. People have many different reasons for theopinions they form. Try to understand what those reasons arebefore reacting to their ideas. If you want your ideas to beheard, it is important that you listen to the opinions of others, asshown in Figure 19. Also, identify your own bias. How does itaffect the way you interpret the issue?


FIELD ACTIVITYFIELD ACTIVITY Critical Thinking and the NewsFind a news article or watch anews broadcast about a currentenvironmental issue. In yourEcolog, write down your initialreaction including your thoughts,feelings, and questions.

Now, look or think again,and answer the followingquestions:• Did the report present differ-ent sides of the issue? Describethe sides.• Did the report seem to favorone side over the other? Howcould you tell?• Did the report use images,sounds, or words that made youfeel a certain way?• Did the report provide anyfacts that helped you form anopinion? Try to list the facts.• Were the sources of the factsprovided? Did the sources seemreliable?• Were the opinions of anyexpert scientists presented? Whowere the scientists?• Is there any information thatwas not provided that might beimportant? Give examples.• When you think about the issuemore, does your opinion change?

Figure 19 � Anyone can express anopinion on environmental issues atstate and local public hearings.

www.scilinks.orgTopic: Solving

EnvironmentalProblems

Code: HE81424

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Second, investigate the source of the information youencounter. Ask yourself if the authors have reason for bias.Also, question the conclusions that are drawn from data. Askyourself if the data support the claims that are made. Thinkcritically about information posted on the Internet—flashygraphics and persuasive text might be hiding a biased agenda.Finally, gather all the information you can before drawing aconclusion.

A Sustainable WorldDespite the differing points of view on the environment, mostpeople support a key goal of environmental science: achievingsustainability. is the condition in which humanneeds are met in such a way that a human population can sur-vive indefinitely. A sustainable world is not an unchangingworld—technology advances and human civilizations continueto be productive. But at the present time we live in a worldthat is far from sustainable. The standard of living in devel-oped countries is high because those countries are usingresources faster than they can be replaced.

The problems described in this chapter are not insurmount-able. Achieving a sustainable world requires everyone’s participa-tion. If individual citizens, industries, and governments cooperate,we can move toward sustainability. For example, you read abouthow Seattle’s Lake Washington is cleaner and healthier now thanit was 30 years ago. Another example is the bald eagle, whichwas once on the brink of extinction. Today bald eagles are mak-ing a comeback, because of the efforts to preserve their habitatand to reduce pollution from the pesticide DDT.

Nevertheless, our environmental problems are significant andrequire careful attention and action. The 21st century will be acrucial time in human history. We must find solutions that allowpeople on all parts of our planet to live in a clean, healthy envi-ronment and have the resources they need for a good life.

What is a sustainable world?■●✓ Reading Check

Sustainability

1. Describe three differences between developing anddeveloped nations using the examples in Table 3.Would you classify Mexico as a developing nation?Explain your answer.

2. Explain why critical thinking is an important skill inenvironmental science.

3. Explain the law of supply and demand, and give anexample of how it relates to the environment.

CRITICAL THINKING4. Applying Ideas The law of supply and demand is a

simplification of economic patterns. What other fac-tors might affect the cost of a barrel of oil?

5. Evaluating Ideas Write a description of “TheTragedy of the Commons.” Do you think thatHardin’s essay is an accurate description of the rela-tionship between individuals, society, and the envi-ronment? WRITING SKILLS

S E C T I O N 2 Review

Figure 20 � These high school stu-dents are taking action to improve theirenvironment. They are cleaning uptrash that is clogging an urban creek.

Section 2 The Environment and Society 21

AstronomyConnection to

Another Earth? If the environ-ment on Earth changed drasti-cally, would we have anywhere togo? There are no other planets inour solar system with an adequaterange of temperatures, a breath-able atmosphere, or the resourcesneeded to sustain humans withour present technology. There maybe other planets like Earth in theuniverse, but the closest planetswe know of are in other solar sys-tems that are light-years away.

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HighlightsC H A P T E R 1

1 Understanding OurEnvironment

2 The Environment and Society

Key Termsenvironmental

science, 5ecology, 6agriculture, 10natural resource, 14pollution, 14biodiversity, 15

Main Ideas� Environmental science is an interdisciplinarystudy of human interactions with the living andnonliving world. One important foundation ofenvironmental science is the science of ecology.

� Environmental change has occurred through-out Earth’s history.

� Hunter-gatherer societies cleared grasslandby setting fires and may have contributed tothe extinction of some large mammals.

� The agricultural revolution caused humanpopulation growth, habitat loss, soil erosion,and the domestication of plants and animals.

� The Industrial Revolution caused rapidhuman population growth and the increaseduse of fossil fuels. Most modern environmen-tal problems began during the IndustrialRevolution.

� The major environmental problems we facetoday are resource depletion, pollution, andloss of biodiversity.

law of supply and demand, 17

ecologicalfootprint, 19

sustainability, 21

� “The Tragedy of the Commons” was aninfluential essay that described the relationshipbetween the short-term interests of the individ-ual and the long-term interests of society.

� The law of supply and demand states thatwhen the demand for a product increases whilethe supply remains fixed, the cost of the prod-uct will increase.

� Environmental problems in developed coun-tries tend to be related to consumption. Indeveloping nations, the major environmentalproblems are related to population growth.

� Describing how sustainability can be achievedis a primary goal of environmental science.

22 Chapter 1 Highlights

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Review

Chapter 1 Review 23

Using Key TermsUse each of the following terms in a separatesentence.

1. agriculture2. natural resource3. pollution4. ecological footprint5. sustainability

Use the correct key term to complete each of thefollowing sentences.

6. The_________ Revolution was characterizedby a shift from human and animal power tofossil fuels.

7. Resources that can theoretically last foreverare called __________ resources.

8. __________ is a term that describes the number and variety of species that live in an area.

Understanding Key Ideas9. An important effect that hunter-gatherer soci-

eties may have had on the environment wasa. soil erosion.b. extinction.c. air pollution.d. All of the above

10. An important effect of the agricultural revo-lution wasa. soil erosion.b. habitat destruction.c. plant and animal domestication.d. All of the above

11. Which of the following does not describe aneffect of the Industrial Revolution?a. Fossil fuels became important energy sources.b. The amount of land and labor needed to

produce food increased.c. Artificial substances replaced some animal

and plant products.d. Machines replaced human muscle and ani-

mal power.12. Pollutants that are not broken down by

natural processes are a. nonrenewable.b. nondegradable.c. biodegradable.d. Both (a) and (c)

13. All of the following are renewable resourcesexcepta. energy from the sun.b. minerals.c. crops.d. fresh water.

14. In his essay, “The Tragedy of the Commons,”one factor that Garrett Hardin failed to con-sider wasa. the destruction of natural resources.b. human self-interest.c. the social nature of humans.d. None of the above

15. The term used to describe the productivearea of Earth needed to support the lifestyleof one person in a particular country iscalleda. supply and demand.b. the ecological footprint.c. the consumption crisis.d. sustainability.

C H A P T E R 1

Root Words As you study it may be helpful tolearn the meaning of important root words. Youcan find these roots in most dictionaries. For example, hydro- means “water.” Once you learnthe meaning of this root, you can learn themeanings of words such as hydrothermal,hydrologist, hydropower, and hydrophobic.

STUDY TIP

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ReviewShort Answer16. Give an example of how environmental

science might involve geology and chemistry. 17. Can biodegradable pollutants cause environ-

mental problems? Explain your answer. 18. In what ways are today’s environmental

resources like the commons described in theessay “The Tragedy of the Commons”?

19. How could environmental concerns conflictwith your desire to improve your standardof living?

20. If you were evaluating the claims made ona Web site that discusses environmentalissues what types of information would youlook for?

21. Can species be considered natural resources?Explain your answer.

Interpreting GraphicsThe graphs below show the difference in energyconsumption and population size in developedand developing countries. Use the graphs toanswer questions 22–24.

22. Describe the differences in the energy con-sumption and population growth of devel-oped and developing countries.

23. Do you think that the percentage of commer-cial energy consumed by developing countrieswill increase or decrease? Explain your answer.

24. Why is information on energy consumptionrepresented in a pie graph, while populationsize is shown in a line graph?

Concept Mapping25. Use the following terms to create a concept

map: geology, biology, ecology, environ-mental science, chemistry, geography, andsocial sciences.

Critical Thinking26. Analyzing Ideas Are humans part of the

environment? Explain your answer.27. Drawing Conclusions Why do you think that

fossil fuels were not widely used until theIndustrial Revolution? Write a paragraphthat describes your thoughts.

28. Evaluating Assumptions Once the sunexhausts its fuel and burns itself out, it can-not be replaced. So why is the sun consid-ered a renewable resource?

29. Evaluating Assumptions Read the descrip-tion of the Industrial Revolution. Were allthe effects of the Industrial Revolution nega-tive? Explain your answer.

Cross-Disciplinary Connection30. Demographics Obtain the 1985 and 2000

census reports for your town or city. Lookfor changes in demographic characteristics,such as population size, income, and age.Make a bar graph that compares some of thecharacteristics you chose. How does yourcity or town compare with national trends?What might be some of the environmentalimplications of these trends?

Portfolio Project31. Make a Diagram Many resources can be

traced to energy from the sun. For example,plants living in swamps millions of years agoused energy from the sun to grow. Over time,some of these plants became coal deposits.When we burn coal today, we are usingenergy that radiated from the sun millions ofyears ago. Choose a resource, and create adiagram that traces the resource back toenergy from the sun.

READING SKILLS

WRITING SKILLS

C H A P T E R 1

24 Chapter 1 Review

Developingcountries

32% Developingcountries

Developed countries

Developedcountries

68%

Commercial Energy Consumption

Population Size

Po

pu

lati

on

(in

bill

ion

s)

Year

1900 1950 20000

1

2

3

4

5

6

?

? ?

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Chapter 1 Review 25

MATH SKILLS

Use the table below to answer questions 32–34.

32. Analyzing Data Make a bar graph thatcompares the garbage produced per personper year in each country.

33. Making Calculations Calculate how muchgarbage is produced each year per squaremile of each country listed in the table.

34. Evaluating Data Use the information in thetable to evaluate the validity of the followingstatement: In countries where populationdensity is high, more garbage is producedper person.

WRITING SKILLS

35. Communicating Main Ideas Briefly describethe relationship between humans and the environment through history.

36. Writing Persuasively Write a persuasiveessay explaining the importance of science ina debate about an environmental issue.

37. Outlining Topics Write a one-page outlinethat describes population and consumptionin the developing and developed world.

Read the passage below, and then answerthe questions that follow.

Think about what you did this morning. Fromthe moment you got up, you were makingdecisions and acting in ways that affect theenvironment. The clothes you are wearing, forexample, might be made of cotton. Severalyears ago the fibers of cotton in your shirtmight have sprouted as seedlings in Egypt orArizona. The cotton seedlings were probablyirrigated with water diverted from a nearbyriver or lake. Chemicals such as pesticides,herbicides, and fertilizers helped the seedlingsgrow into plants. Furthermore, the metals inthe machines that harvested the cotton weremined from the Earth’s crust. In addition, thevehicles that brought the shirt to the storewhere you bought it were powered by fossilfuels. Fossil fuels came from the bodies of tinyorganisms that lived millions of years ago. Allof these connections can make environmentalscience a complex and interesting field.

1. According to the passage, which of thefollowing conclusions is true?a. Decisions we make in everyday life do

not affect our environment.b. Cotton comes from minerals in the

Earth’s crust.c. Many different things in the environ-

ment are connected and interrelated.d. There is no connection between a

cotton shirt and the resources neededto grow a field of cotton.

2. Which of the following statements best describes the meaning of the termirrigation?a. Irrigation is a connection between liv-

ing things in the environment.b. Irrigation is the artificial process by

which water is supplied to plants.c. Irrigation is the process of diverting

water from a stream or lake.d. Irrigation is the process by which cot-

ton seedlings grow into plants.

U.S. Japan Indonesia

People per 78 829 319square mile

Garbage produced 720 kg 400 kg 43 kgper person per year

READING SKILLS

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CC H A P T E R 1 Standardized Test PrepUnderstanding ConceptsDirections (1–4): For each question, write on aseparate sheet of paper the letter of the correctanswer.

1 How do scientists characterize a nonrenewable resource?A. a resource that is used by humansB. a resource that cannot be replacedC. a resource that can be replaced relatively

quicklyD. a resource that takes more time to

replace than to deplete

2 Which of the following is an importantfoundation of environmental science? F. ecologyG. economicsH. meteorologyI. political science

3 Which of the following phrases describesthe term biodiversity?A. species that have become extinctB. the animals that live in an areaC. species that look different from one

anotherD. the number and variety of species that

live in an area

4 Energy from the sun, water, air, wood, andsoil are all examples of what kind ofenergy?F. ecological energyG. organic energyH. renewable energyI. solar energy

Directions (5–6): For each question, write a shortresponse.

5 Pollution is created when societies producewastes faster than they can be disposed of.Identify the two main types of pollutants.

6 Economic forces influence the use of natural resources. One rule of economics is the law of supply and demand. Analyzehow economic forces affect the usage ofnonrenewable resources.

Reading SkillsDirections (7–9): Read the passage below. Thenanswer the questions.

Early hunter-gatherer groups began to col-lect the seeds of the plants they gathered andto domesticate animals in their environment.This practice of agriculture started in manyparts of the world more than 10,000 yearsago, and had such a dramatic impact onhuman societies and their environment that itis often called the agricultural revolution. Anarea of land could now support up to 500times as many people by farming than it couldby hunting and gathering. As populationsgrew, they began to concentrate in smallerareas.

As grasslands, forests, and wetlands werereplaced with farmland, habitat was destroyed.In addition, much of the converted land wasfarmed poorly and became infertile. Thedestruction of farmland had far-reaching environmental effects.

7 The practice of gathering seeds and domesticating some animals led to A. a reduction in the kinds of food

people ateB. the extension of the prairies as open

grasslandC. the disappearance of some species of

large mammalsD. a growth in population at an

unprecedented rate

8 In what ways did the agricultural revolution increase pressure on local environments?

9 What happened to human populations asthey became larger?F. They began to concentrate in smaller

areas.G. They remained dispersed.H. They became hunter-gatherers.I. Most became extinct.

26 Chapter 1 Standardized Test Prep

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TestWhen reading a graphthat shows a changein some variable overtime, keep in mind thatthe steepness anddirection of a curveindicate the relativerate of change at agiven point in time.

Chapter 1 Standardized Test Prep 27

Interpreting Graphics

Directions (10–13): For each question below, record the correct answer ona separate sheet of paper.

0 Population growth can result in what ethical environmental problem,addressed by ecologist Garrett Hardin in “The Tragedy of the Commons”?A. the conflict between water resources and industrial growthB. the conflict between forest resources and the lumber companiesC. the conflict between political interests and international energy useD. the conflict between individual interests and the welfare of society

The line graph below shows the world population between the years 1600and 2000. Use this graph to answer questions 11 and 12.

World Population (1600–2000)

q What was the total population increase between the years 1600 and1900?F. 0.6 billionG. 0.9 billionH. 1.0 billionI. 1.5 billion

w If the rate of growth from 1900–1950 had been the same as the rateof growth from 1950–2000, what would the world population havebeen at the end of the century?A. more than 7 billionB. more than 10 billionC. more than 15 billionD. more than 20 billion

e Which of the following characterizes the environmental consequencesof the current population trend?F. More people mean more housing construction.G. The need for food and resources is growing rapidly.H. The standard of living has risen around the world.I. There is no connection between population growth and

environment.

Po

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lati

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(in

bill

ion

s)

1600 1700 1800 1900 2000

Year

6.5

5.5

4.5

3.5

2.5

1.5

0.5

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28 Chapter 1 Exploration Lab

What’s in an Ecosystem?How well do you know the environment around your home orschool? You may walk through it every day without noticing mostof the living things it contains or thinking about how they survive.Ecologists, on the other hand, observe organisms and seek tounderstand how they interact. In this lab, you will play the role ofan ecologist by closely observing part of your environment.

Procedure1. Use a tape measure or meter stick to measure a 10 m � 10 m

site to study. Place one stake at each corner of the site. Loopthe string around each stake, and run the string from onestake to the next to form boundaries for the site.

2. Survey the site, and then prepare a site map of the physicalfeatures of the area on the poster board. For example, showthe location of streams, sidewalks, trails, or large rocks, andindicate the direction of any noticeable slope.

3. Create a set of symbols to represent the organisms at yoursite. For example, you might use green triangles to representtrees, blue circles to represent insects, or brown squares torepresent animal burrows or nests. At the bottom or side ofthe poster board, make a key for your symbols.

4. Draw your symbols on the map to show the location and rela-tive abundance of each type of organism. If there is not enoughspace on your map to indicate the specific kinds of plants andanimals you observed, record them in your notebook.

5. In your notebook, record any observations of organisms intheir environment. For example, note insects feeding onplants or seeking shelter under rocks. Also describe thephysical characteristics of your study area. Consider the following characteristics:a. Sunlight Exposure How much of the area is exposed to

sunlight?b. Soil Is the soil mostly sand, silt, clay, or organic matter?c. Rain When was the last rain recorded for this area? How

much rain was received?d. Maintenance Is the area maintained? If so, interview the

person who maintains it and find out how often the site iswatered, fertilized, treated with pesticides, and mowed.

e. Water Drainage Is the area well drained, or does it havepools of water?

f. Vegetation Cover How much of the soil is covered withvegetation? How much of the soil is exposed?

6. After completing these observations, identify a 2 m � 2 marea that you would like to study in more detail. Stake outthis area, and wrap the string around the stakes.

Objectives� Survey an area of land and deter-

mine the land’s physical featuresand the types of organisms thatlive there.

� Identifypossible relationships between theorganisms that live in the area ofland you surveyed.

Materialshand lensmarkers or felt-tip pens of

several different colorsnotebookpen or pencilposter boardstakes, (4) string, about 50 mtape measure or metric ruler

optional materials: field guides toinsects or plants

USING SCIENTIFIC METHODS

Exploration Lab: FIELD ACTIVITYC H A P T E R 1

� Marking a Site Use stakes andstring to mark a site that you willobserve in detail.

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Chapter 1 Exploration Lab 29

7. Use your hand lens to inspect the area. Be careful not to dis-turb the soil or the organisms. Then record the types ofinsects and plants you see.

8. Collect a small sample of soil, and observe it with your handlens. Record a description of the soil and the organisms thatlive in it.

Analysis1. Organizing Data Return to the classroom, and display your

site map. Use your site map, your classmates’ site maps, andyour notes to answer the followingquestions. Write your answers inyour notebook.

2. Analyzing Data Write one para-graph that describes the 10 m �10 m site you studied.

3. Analyzing Data Describe the 2 m � 2 m site you studied. Is this site characteristic of the larger site?

Conclusions4. Interpreting Conclusions What

are the differences between theareas that your classmates stud-ied? Do different plants andanimals live in different areas?

5. Making Predictions As the seasons change, the types oforganisms that live in the areayou studied may also change.Predict how your area mightchange in a different season orif a fire or flood occurred. If possible, returnto the site at different times throughout the year and record your observations.

� Site Maps Your site map shouldbe as detailed as possible, and itshould include a legend.

1. Asking Questions Based on what you have learned, thinkof a question that explores how the components of the areayou observed interact with each other. For example, youmight want to consider the influence of humans on the site;study a particular predator/prey relationship; or explore theeffects of physical features, such as water or sunlight, on thegrowth or behavior of organisms. Write a description ofhow you would investigate this topic. WRITING SKILLS

Extension

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CHICKEN OF THE TREES In the stillness of predawn, the airwarms over the Carara BiologicalPreserve in Costa Rica. Severalthousand eggs in sun-heated incuba-tors just below the surface of theEarth stir in response. Within theseeggs are tiny iguanas—lizards thatwill eventually emerge, grow to alength of 1.5 m to 2.0 m (5 ft to 6.5ft), and weigh up to 6 kg (13 lb).

What’s going on here? Well,these giant lizards are being raisedso that they can be released intothe rain forest. It’s part of a projectled by German-born scientist Dr.Dagmar Werner. Her goal is tohelp restore an iguana populationthat has been severely reduced inthe past several decades.

The lizard has suffered from theeffects of hunting, pollution, andhabitat destruction by people whoclear the rain forest for farming.Prime iguana habitat is at the edgeof the forest—where a combinationof open areas, scrub, and treesoccur. Historically, these areas arethe type of habitat that humans

most often destroy when convert-ing forestland to farmland. Peoplecut down the forest at its edges—which just happens to be primehabitat for iguanas and otherplants and animals.

Back at the IguanaRanchDr. Werner’s “iguana ranch” preserve has artificial nests wherefemales can lay their eggs in apredator-free environment. Afterthey hatch, the young lizards areplaced in a temperature- andhumidity-controlled incubator andgiven a special diet. As a result, theiguanas grow faster and strongerand are better protected frompredators than their noncaptivecounterparts.

In the first five years of herproject, more than 80,000 iguanaswere released into the wild.Ordinarily, less than 2 percent ofall iguanas survive to adulthood inthe wild, but Dr. Werner’s iguanashave a 77 percent survival rate.Dr. Werner knows this becauseafter she releases the iguanas intothe rain forest, the lizards aretracked and monitored to deter-mine whether they have success-fully adapted to life in the wild.

Passing It OnSince the 1980s, Dr. Werner hasimproved the iguanas’ chances ofsurvival by breeding them andreleasing thousands of young igua-nas into the wild. But Dr. Wernersoon realized that this effort wasnot enough, so she began trainingother people to do the same.

Because she knew there was notime to lose, Dr. Werner took animmediate and drastic approach tosolving the problem. She combinedher captive-breeding program atthe preserve with an education pro-gram that shows farmers that thereis more than one way to make aprofit from the rain forest. Instead

� These are iguanas at the CararaBiological Preserve in Costa Rica.

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Chapter 1 Making a Difference 31

What Do You Think?How does Dr. Werner’s projectprotect iguanas and help localfarmers too? Why do you thinkthat she trains farmers to raiseand value iguanas—what couldher larger goal be? Can youthink of a similar project thatwould be suitable for your area?

of raising cattle (and cutting downrain forest to do so), she encour-ages local farmers to raise iguanas,which can be released into the wildor sold for food. Known as the“chicken of the trees,” this lizardhas been a favored source of meatamong native rain-forest inhabi-tants for thousands of years.

Not only do farmers profitfrom the sale of iguana meat, theyalso produce iguana leather andother handicrafts from the lizard.

Fundación Pro IguanaVerdeWith Dr. Werner’s methods, farmerscan release many iguanas into thewild and earn a good living. Butconvincing farmers to use her meth-ods hasn’t been easy. According toDr. Werner, “Many locals have

never thought of wild animals ascreatures that must be protected inorder to survive. That’s why somany go extinct.” To get her mes-sage across, Dr. Werner has estab-lished the Fundación Pro IguanaVerde (the Green IguanaFoundation). This organizationsponsors festivals and educationseminars in local communities.These activities promote the tradi-tional appeal of the iguana, increasecivic pride in the animal, and

heighten awareness about theiguana’s economic importance.

By demonstrating that the needsof all concerned parties can be metwhen attempting to save an endan-gered species, Dr. Werner has revo-lutionized the concepts of speciespreservation and economic devel-opment. This hard-working scien-tist has hit upon a solution thatmay encourage farmers throughoutCentral America to “have theirlizards and eat them too.”

� Dr. Werner and an associate dis-cuss how the iguana can be farmed.

� Dr. Werner has established aninnovative way to raise the numberof iguanas living in the wild.

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hes08 ch01 004-015 s01 8/18/06 8:49 am page 4 science and ... · nary science, which means that it...

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