section 3 grassland, desert, and tundra...

In climates that have less rainfall, forest biomes are replaced bysavanna, grassland, and chaparral biomes. As less rain falls inthese biomes, they change into desert and tundra biomes. As pre-cipitation decreases in an area, the diversity of the species in thearea also decreases. But while the number of different species isoften smaller in areas that have less precipitation, the number ofindividuals of each species present may be very large.

SavannasParts of Africa, western India, northern Australia, and some partsof South America are covered by grassland called savanna.

are located in tropical and subtropical areas near theequator and between tropical rain forest and desert biomes.Because savannas are full of grasses, scattered trees, and shrubs,savannas contain a large variety of grazing animals and the preda-tors that hunt them. As shown in Figure 16, savannas receive lit-tle precipitation throughout the year. Savannas have a wet seasonand a dry season. Many animals of the savanna are active onlyduring the wet season. Grass fires sweep across the savanna dur-ing the dry season and help restore nutrients to the soil.

Plants of the Savanna Because most of the rain falls duringthe wet season, plants must be able to survive prolonged pe-riods without water. Therefore, some trees and grasses havelarge horizontal root systems by which they obtain water dur-ing the dry season. These root systems also enable plants toquickly grow again after a fire. The coarse savanna grasseshave vertical leaves that expose less of their surface area to thehot sun to further help the grasses conserve water. Some treesof the savanna also lose their leaves during the dry season toconserve water. Trees and shrubs often have thorns or sharpleaves that keep hungry herbivores away.

Savannas

Objectives� Describe the difference between

tropical and temperate grasslands.� Describe the climate in a chaparral

biome.� Describe two desert animals and

the adaptations that help themsurvive.

� Describe one threat to the tundrabiome.

Key Termssavannatemperate grasslandchaparraldeserttundrapermafrost

S E C T I O N 3

Grassland, Desert, and Tundra Biomes

Tropical Savanna(Nairobi, Kenya)

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Figure 16 � Savannas have periodsof heavy rainfall followed by periodsof drought.

Section 3 Grassland, Desert, and Tundra Biomes 155Copyright© by Holt, Rinehart and Winston. All rights reserved.

Animals of the Savanna Grazing herbivores such as the elephantsshown in Figure 17, have adopted a migratory way of life. Theyfollow the rains to areas of newly sprouted grass and wateringholes. Some predators follow and stalk the migratory animals forfood. Many savanna animals give birth only during the rainy sea-son, when food is most abundant and the young are more likely tosurvive. Also, some species of herbivores reduce competition forfood by eating vegetation at different heights than other species do.For example, small gazelles graze on grasses, black rhinos browseon shrubs, and giraffes feed on tree leaves.

Temperate GrasslandsA is a biome that is dominated by grassesand that has very few trees. Most temperate grasslands have hotsummers and cold winters. The amount of rainfall that a temper-ate grassland receives is moderate compared to the amount a for-est receives. On average, a temperate grassland can receive 50 to88 cm of precipitation per year, as shown in Figure 18. Althoughtemperate grasslands may seem harsh and dry, they have the mostfertile soil of any biome. So, many grassland biomes have beenreplaced with crops such as corn, soybeans, and wheat. Few natu-ral temperate grasslands remain because many have been replacedby farms and grazing areas.

temperate grassland

156 Chapter 6 Biomes

Figure 17 � Herbivores of thesavanna reduce their competition forfood by feeding on vegetation locatedat different heights. Elephants feed ontree leaves, while impala graze ongrasses.

Temperate Grassland(Wichita, Kansas)

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Figure 18 � Temperate grasslandsare characterized by small amountsof rainfall, periodic droughts, andhigh temperatures in the summer.

GeofactDeep Soil Gravel or sand becomesfertile soil when decomposersslowly break down organic mattersuch as dead leaves. Decomposerswork most effectively in hot, wetweather. As a result, the world’sdeepest soil is in grasslands. Ingrassland biomes, winters are coldand summers are dry, which causesleaves to break down slowly. So,organic matter builds up over time.Some North American prairies hadmore than 2 m of topsoil when thefirst farmers arrived.

Copyright© by Holt, Rinehart and Winston. All rights reserved.

Temperate grasslands are located on the interiors of continentswhere too little rain falls for trees to grow. Grassland biomesinclude the prairies of North America, the steppes of Russia andUkraine, and the pampas of South America, as shown in Figure 19.Mountains often play a crucial role in maintaining grasslands. Forexample, in North America, rain clouds from the west are blockedby the Rocky Mountains, so the shortgrass prairie east of the moun-tains receives only about 25 cm of rain a year. Rainfall increases asyou move eastward, so taller grasses and some shrubs can grow inareas where more rain falls. Heavy precipitation is rare in the grass-lands, so sizzling temperatures in the summer make the grasslandssusceptible to fires, which are common in grassland biomes.

Plants of Temperate Grasslands Prairie grasses and wildflowersare perennials, plants that survive from year to year. The root sys-tems of prairie grasses form dense layers that survive drought andfire as well as hold the soil in place. The amount of rainfall in anarea determines the types of plants that will grow in that area.Figure 20 shows how root depth and grass height vary dependingon the amount of rainfall. Few trees survive on the grasslandsbecause of the lack of rainfall, fire, and the constant winds.

Section 3 Grassland, Desert, and Tundra Biomes 157

Figure 19 � Temperate grasslandscan be named according to the vege-tation that grows there. Steppes (left),have shorter grasses and are located inEurope and Asia. Pampas (right), aremade up of clusters of feathery grassesand are located in South America.

HistoryConnection to

The State of Bison More than60 million bison once roamed thetemperate grasslands of NorthAmerica. But these large grass-eating mammals were almostbrought to extinction by the late1800s because of hunting bywestern settlers. By 1889, fewerthan 1,100 bison remained inNorth America! The first bill tosave the bison was introduced byCongress in 1874. In 1903,President Theodore Rooseveltstarted the National WildlifeRefuge System to provide pro-tected areas for bison and otheranimals. Today, North Americahas more than 200,000 bison.

Shortgrass prairie(about 25 cm rain per year)

Mixed or middlegrass prairie

(about 50 cm rain per year)

Tallgrass prairie(up to 88 cm rain per year)

Figure 20 � The height of grasslandplants and the depth of their rootsdepend on the amount of rainfallthat the grasslands receive.


Animals of Temperate Grasslands Grazing animals, such aspronghorn antelope and bison, have large, flat back teeth forchewing the coarse prairie grasses. Other grassland animals, suchas badgers, prairie dogs, and owls, live protected in undergroundburrows as shown in Figure 21. The burrows shield the animalsfrom fire and weather and protect them from predators on theopen grasslands.

Threats to Temperate Grasslands Farming and overgrazing havechanged the grasslands. Grain crops cannot hold the soil in placeas well as native grasses can because the roots of crops are shal-low, so soil erosion eventually occurs. Erosion is also caused byovergrazing. When grasses are constantly eaten and trampled, thegrasses cannot regenerate or hold the soil. This constant use canchange fruitful grasslands into less productive, desertlike biomes.

ChaparralPlants that have leathery leaves are commonly found in temperatewoodland biomes. Temperate woodland biomes have fairly dryclimates but receive enough rainfall to support more plants thana desert does. Temperate woodlands consist of scattered treecommunities made up of coniferous trees such as piñon pines andjunipers, as shown in Figure 22.

is a type of temperate woodland biome that is dominated by more broad-leafed evergreen shrubs than by ever-green trees. Look at the famous white letters that spell Hollywood

Chaparral

158 Chapter 6 Biomes

Figure 21 � Prairie dogs, such asthose shown here, live in temperategrasslands. Prairie dogs live incolonies and burrow in the groundto build mounds, holes, and tunnels.

Figure 22 � Temperate woodlandsare usually too dry to support a for-est, but they receive sufficient pre-cipitation to support vegetation thatgrows in bunches, such as the piñonand juniper trees shown here.

QuickLABSponging It UpProcedure1. Completely saturate two small

sponges with water and allowthe excess water to drain off.

2. Measure each sponge’s mass byusing an electric balance.Record the mass.

3. Using plastic wrap, completelycover one of the sponges.

4. Place the sponges outside in a sunny place for 10 to 15 minutes.

5. Measure each sponge’s massafter removing it from outside.Record the mass.

Analysis1. Which sponge lost the most

mass? Why?2. How was the covering you cre-

ated for the sponge similar tothe adaptations of the plants inthe chaparral biome?


across green and brown California hills in Figure 23. Now imaginethe scrub-covered settings common in old westerns. Both of theselandscapes are part of the chaparral biome. As shown in Figure 24,chaparral is located in the middle latitudes, about 30° north andsouth of the equator. Chaparral is located primarily in coastalareas that have Mediterranean climates. Chaparral biomes typi-cally have warm, dry summers and mild, wet winters.

Plants of the Chaparral Most chaparral plants are low-lying, ever-green shrubs and small trees that tend to grow in dense patches.Common chaparral plants include chamise, manzanita, scrub oak,olive trees, and herbs, such as sage and bay. These plants havesmall, leathery leaves that retain water. The leaves also contain oilsthat promote burning, which is an advantage because natural firesdestroy trees that might compete with chaparral plants for light andspace. Chaparral plants are so well adapted to fire that they canresprout from small bits of surviving plant tissue. The flammableoils give plants such as sage their characteristic taste and smell.

Animals of the Chaparral A common adaptation of chaparral ani-mals is camouflage, shape or coloring that allows an animal toblend into its environment. Animals such as quail, lizards, chip-munks, and mule deer have a brownish gray coloring that lets themmove through the brush without being noticed.

Threats to the Chaparral Worldwide, the greatest threat to chap-arral is human development. Because chaparral biomes get a lot ofsun, are near the oceans, and a have a mild climate year-round,humans tend to develop land for commercial and residential use.


Chaparral(Santa Barbara, California)

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Figure 24 � Chaparral biomes arelocated in areas that haveMediterranean climates.

Figure 23 � The chaparral biome inthe Hollywood hills is home to plantssuch as the manzanita, which isshown above.


DesertsWhen some people think of a desert, they think of the hot sandthat surrounds the Egyptian pyramids. Other people picture theSonoran Desert and its mighty saguaro cactuses, or the magnificentrock formations of Monument Valley in Arizona and Utah. Manykinds of deserts are located throughout the world, but one charac-teristic that they share is that they are the driest places on Earth.

are areas that receive less than 25 cm of precipitationa year and have little or no vegetation. Deserts, as shown in Figure25, also have extreme temperatures. Hot deserts, such as Arizona’sSonoran Desert and the Sahara in Africa, are closer to the equatorthan are cold deserts, such as the Gobi Desert in China and theGreat Basin of the western United States. Deserts are often locatedin areas near large mountain ranges because mountains can blockthe passage of moisture-filled clouds, which limits precipitation.

Deserts

Desert(Cairo, Egypt)

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Figure 25 � Deserts are the driestplaces on Earth. They typicallyreceive less than 25 cm of precipita-tion a year.

160 Chapter 6 Biomes160

� The flapnecked chameleon livesin the deserts of Botswana.

� The plants of the Sonoran Desertin Arizona collect and retain waterafter rain showers to survive thehot desert temperatures.


Plants of the Desert All desert plants have adaptations forobtaining and conserving water, which allows the plants to live indry, desert conditions. Plants called succulents, such as cactuses,have thick, fleshy stems and leaves that store water. Their leavesalso have a waxy coating that prevents water loss. Sharp spineson cactuses keep thirsty animals from devouring the plant’s juicyflesh. Rainfall rarely penetrates deeply into the soil, so manyplants’ roots spread out just under the surface of the soil toabsorb as much rain as possible.

Instead of living in dry conditions, some desert plants areadapted to survive for long periods of time without water. Whenconditions are too dry, some plants die and drop seeds that staydormant in the soil until the next rainfall. Then, new plants quicklygerminate, grow, and bloom before the soil becomes dry again.Some desert plants have adapted so that they can survive even iftheir water content drops to as low as 30 percent of their mass.Water levels below 50 to 75 percent are fatal for most plants.

Animals of the Desert Reptiles, such as Gila monsters and rattlesnakes, have thick, scaly skin that prevents water loss.Amphibians, such as the spadefoot toad, survive scorching desertsummers by estivating—burying themselves in the ground andsleeping through the dry season. Some animals, such as the elfowl shown in Figure 26, nest in cactuses to avoid predators.Desert insects and spiders are covered with body armor that helpsthem retain water. In addition, most desert animals are nocturnal,which means they are active mainly at night or at dusk, when theair is cooler.


Figure 26 � Desert plants surviveharsh conditions by growing deeproots to reach groundwater and byhaving specialized structures thatlimit the loss of water. Desert animalsbury themselves underground or bur-row in cactuses to avoid extremetemperatures and predators.

FIELD ACTIVITY FIELD ACTIVITY Miniature Desert Create aminiature desert by growing asmall cactus garden. Purchasetwo or three small cactus plants,or take several cuttings from alarge cactus. To take cuttings,carefully break off the shootsgrowing at the base of the parentcactus. Place the plants in rockyor sandy soil similar to the soil ina desert. Keep the cactuses inbright sunlight, and do not waterthem frequently. Record yourobservations of your cactus gar-den in your Ecolog.

� Elf owls burrow in cactuses to avoidhot temperatures during the day.

� This sidewinder has a unique wayof moving so that only small portionsof its body are in contact with thehot sands at any one time.


Tundrais a biome that is dominated by grasses, lichens, and

herbs and that is located primarily north of the Arctic Circle, asshown in Figure 27. The tundra soil supports mostly toughgrasses and shrubs. Summers are short in the tundra, so only thetop few centimeters of soil thaw. Plants flower in the summer, asshown in Figure 28. Underneath the topsoil is a layer of soilcalled which is permanently frozen soil. The tundrabecomes dotted with bogs and swamps when the top layer of soilthaws. In summer, these wet areas are ideal breeding grounds forhuge numbers of swarming insects, such as mosquitoes andblackflies, and for the many birds that feed on the insects.

Vegetation of the Tundra Mosses and lichens, which can growwithout soil, cover vast areas of rocks in the tundra. The soil isthin, so plants have wide, shallow roots to help anchor themagainst the icy winds. Most flowering plants of the tundra, such ascampion and gentian, are short. Growing close to the ground keepsthe plants out of the wind and helps them absorb heat from thesunlit soil. Woody plants and perennials such as willow and juniperhave evolved dwarf forms and grow flat or grow along the ground.

permafrost,

Tundra

162 Chapter 6 Biomes162

Tundra(Reykjavik, Iceland)

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Figure 27 � The precipitation thatthe tundra biome receives remainsfrozen much of the year.

Figure 28 � During its brief summer,the Alaskan tundra is covered byflowering plants and lichens.


Animals of the Tundra Millions of migratorybirds fly to the tundra to breed in the summer.Food is abundant in the form of plants, mollusks,worms, and especially insects. Caribou, as shownin Figure 29, migrate throughout the tundra insearch of food and water. Hunters such as wolvesroam the tundra and prey on caribou, deer,moose, and smaller animals, such as lemmings,mice, and rabbits. These rodents burrow under-ground during the winter but they are still active.Many animals that live in the tundra year-round, such as arctic foxes,lose their brown fur and grow white fur that camouflages them withthe winter snow. These animals are also extremely well insulated.

Threats to the Tundra The tundra is one of the most fragilebiomes on the planet. The food chains are relatively simple, so theyare easily disrupted. Because conditions are so extreme, the land iseasily damaged and slow to recover. Until recently, these areas wereundisturbed by humans. But oil has been located in some tundraregions, such as Prudhoe Bay in northern Alaska. Oil exploration,extraction, and transport has disrupted the habitats of the plantsand animals in many parts of the tundra. Pollution caused by spillsor leaks of oil and other toxic materials may also poison the foodand water sources of the organisms that live in the tundra.


1. Describe two desert animals and the adaptationsthat help them survive.

2. Describe how tropical grasslands differ from temper-ate grasslands.

3. Compare the plants that live in deserts with theplants that live in the tundra biome.

4. Describe one threat to the tundra biome.

CRITICAL THINKING5. Making Inferences Former grasslands are among

the most productive farming regions. Read thedescription of temperate grasslands in this sectionand explain why this statement is true.

6. Analyzing Relationships Explain why migratoryanimals such as elephants, giraffes, and bison usuallylive in temperate grasslands.

READING SKILLS

S E C T I O N 3 Review

079_PFPO

Figure 29 � Many migratory ani-mals, such as geese (left) and caribou(below), return to the tundra eachyear to breed.

MATHPRACTICEU.S. Oil Production Onaverage, the United States produces an estimated 8.1 million barrels of oil per day. Howmany millions of barrels of oil doesthe United States produce in 1 year?If all of the oil-producing countriesof the world produce an estimated74.13 million barrels of oil per day,what percentage of worldwide oildoes the United States produce?


HighlightsC H A P T E R 6

1 What Is a Biome?

2 Forest Biomes

3 Grassland, Desert, and Tundra Biomes

Key Termsbiome, 143climate, 144latitude, 145altitude, 145

Main Ideas� Scientists classify the ecosystems of the worldinto large areas called biomes.

� Biomes are described by their plant lifebecause the plants that grow in an area deter-mine what other organisms live there.

� Temperature, precipitation, latitude, and alti-tude are factors that affect climate, whichdetermines the types of the plants that cangrow in an area.

tropical rain forest,146

emergent layer, 148canopy, 148epiphyte, 148understory, 148temperate rain

forest, 151temperate deciduous

forest, 152taiga, 153

� The major forest biomes include tropical rainforests, temperate rain forests, temperate decid-uous forests, and taiga.

� Tropical rain forests receive heavy rains andhigh temperatures throughout the year. Theyreceive about 200 to 450 cm of rainfall a year.They are the most diverse of all biomes.

� Temperate deciduous forests experience seasonal variations in temperature and precipi-tation. They receive 75 to 125 cm of precipi-tation a year.

� Forest biomes are threatened by deforesta-tion through logging, ranching, and farming.

savanna, 155temperate grassland,

156chaparral, 158desert, 160tundra, 162permafrost, 162

� Savannas are located north and south oftropical rain forests and have distinct wet sea-sons. Savannas receive 90 to 150 cm of precipi-tation a year.

� Temperate grasslands get too little rainfall tosupport trees. Grasslands are dominated mostlyby different types of grasses and floweringplants. Shortgrass prairies receive about 25 cmof precipitation a year.

� Deserts are the driest biomes on Earth.Deserts receive less than 25 cm of precipitationa year.

� Plants and animals found in each biomeadapt to the environment in which they live.

164 Chapter 6 HighlightsCopyright© by Holt, Rinehart and Winston. All rights reserved.

Review

Chapter 6 Review 165

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

1. biome2. climate3. epiphyte4. tundra5. permafrost

For each pair of terms, explain how the meaningsof the terms differ.

6. understory and canopy7. latitude and altitude8. chaparral and desert9. tropical rain forest and temperate deciduous

forest

Understanding Key Ideas10. Approximately what percentage of the Earth’s

species do tropical rain forests contain?a. 7 percentb. 20 percentc. 40 percentd. 50 percent

11. Animal species of the tropical rain foresta. compete more for available resources than

species native to other biomes do.b. have specialized adaptations to avoid com-

petition.c. have adaptations to cope with extreme

variations in climate.d. are never camouflaged.

12. Migration of animals in the savanna ismostly a response toa. predation.b. altitude.c. rainfall.d. temperature.

13. Spadefoot toads survive the dry conditionsof the desert bya. migrating to seasonal watering holes.b. finding underground springs.c. burying themselves in the ground.d. drinking cactus juice.

14. The tundra is most suitable to an animalthata. requires nesting sites in tall trees.b. is coldblooded.c. has a green outer skin for camouflage.d. can migrate hundreds of kilometers each

summer.15. A biome that has a large amount of rainfall,

high temperature, and poor soil is aa. temperate woodland.b. temperate rain forest.c. tropical rain forest.d. savanna.

16. The two main factors that determine whereorganisms live area. soil type and precipitation.b. temperature and precipitation.c. altitude and precipitation.d. temperature and latitude.

17. Which of the following biomes containslarge trees?a. savannab. temperate rain forestc. chaparrald. desert

18. The most common types of plants in thetaiga biome area. deciduous trees.b. short shrubs.c. coniferous trees.d. grasses.

C H A P T E R 6

Concept Maps Remembering words and under-standing concepts are easier when information isorganized in a way that you recognize. For exam-ple, you can use key terms and key concepts tocreate a concept map that links them together ina pattern you will understand and remember.

STUDY TIP


Savanna

Temperate grasslandTemperate forest Desert

Temperate

Tropical

Subarctic

Arctic

Taiga

Tundra

Tropical rain forest Desert

DryWet

HotD

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asin

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Decreasing moisture

ReviewShort Answer19. Unlike the jungles you see in movies, the

floor of an undisturbed tropical rain forestusually lacks much vegetation. Explain whyit lacks vegetation.

20. What is the relationship between root sys-tems and erosion in a grassland ecosystem?

21. How might a mountain affect where particu-lar types of biomes are located?

22. Well-preserved mammoths have been foundburied in the tundra. Explain why the tundrapreserves animal remains well.

23. How does deforestation contribute to achange in climate and increase the chance offloods in a biome?

Interpreting GraphicsUse the diagram below to answer questions24–26.24. Why are tall trees found in taiga biomes but

not in tundra biomes?25. As moisture decreases, what happens to the

amount of vegetation in an area?26. What does the diagram tell you about the

temperature of and precipitation in temper-ate grasslands?

Concept Mapping27. Use the following terms to create a concept

map: threats to an ecosystem, erosion, over-grazing, logging, grasslands, rain forests,tundra, deserts, oil extraction, and irrigation.

Critical Thinking28. Comparing Processes American prairies and

Asian steppes contain different plant speciesbut are dominated by grasses. Write a shortparagraph that explains why the two grass-lands contain different species but the sametypes of plants.

29. Classifying Information Read the descrip-tion of tropical rain forests in this chapter,and list two factors that are responsible forthe biodiversity of this biome. Describe tworeasons for the decline of tropical rainforests, and discuss actions that some coun-tries have taken to protect tropical rainforests.

30. Analyzing Relationships If you took a popu-lation of squirrels from the southeasternUnited States and introduced them into aCentral American rain forest, they wouldprobably not survive. Why do you think thesquirrels would not survive even though theyare naturally adapted to life in a forest?

31. Making Inferences How might prairie firesset from natural and human causes haveaffected the evolution of fire resistance inprairie grasses?

Cross-Disciplinary Connection32. Geography Use a world map to find loca-

tions of the various biomes. Then, make aposter that contains photos or illustrationsof plants and animals native to each biome.

Portfolio Project33. Food Webs in Your Community Do a special

project on the ecosystems in your community.Use field guides of your area to find out whatplants and animals live in your community.Then, draw a food web that shows howorganisms in each ecosystem could be related.

READING SKILLS

WRITING SKILLS

C H A P T E R 6

166 Chapter 6 Review

?

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Chapter 6 Review 167

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

The Tropics and other regions of high biodi-versity include some of the economically poor-est countries on Earth. These countries aretrying to use their natural resources to buildtheir economies and to raise the standard ofliving for their citizens. Several conservationstrategies offer ways for developing countriesto benefit economically from preserving theirbiodiversity.

For example, in a debt-for-nature swap,richer countries or private conservationorganizations will sometimes pay some ofthe debts of a developing country. Inexchange, the developing country agrees totake steps to protect its biodiversity, such assetting up a preserve or launching an educa-tion program for its citizens. Another idea tohelp local people make money from intactecosystems is to set up a national park toattract tourists. People who want to see theecosystem and its unique organisms will paymoney for nature guides, food, and lodging.This idea is called ecotourism.

1. The main objective of both debt-for-nature swap and ecotourism isa. economic gain.b. education of citizens. c. preservation of biodiversity.d. Both (a) and (c)

2. According to the passage, which of thefollowing statements is true?a. Regions of high biodiversity are not

worth saving.b. Intact ecosystems are those ecosystems

that are most developed.c. Debt-for-nature swap is an example of

international compromise.d. Launching education programs for citi-

zens does not help protect ecosystems.

MATH SKILLS

Use the table below to answer quesions 34–35.

34. Making Calculations What percentage oftropical rain forest is being destroyed eachyear in country A? in country D?

35. Interpreting Statistics If the rate of tropi-cal rain forest deforestation remains con-stant in country E, in how many years willall of the tropical rain forest in that coun-try be destroyed?

WRITING SKILLS

36. Communicating Main Ideas Describe theimportance of conserving the biomes of theworld. What can you do to help conserve theworld’s biomes?

37. Writing From Research Choose one biomeand research the threats that exist against it.Write a short essay that describes the threatsand any actions that are being taken to helpsave the biome.

Amount of Tropical Rainforest

Amount ofAmount of annualtropical rain deforestation

Country forest (km2) (km2/y)

A 1,800,000 50,000

B 55,000 3,300

C 22,000 6,000

D 530,000 12,000

E 80,000 700

Now that you have read the chapter, take amoment to review your answers to the ReadingWarm-Up questions in your EcoLog. If necessary,revise your answers.

READING FOLLOW-UP


168 Chapter 6 Exploration Lab

Identify Your Local BiomeIn what biome do you live? Do you live in a temperate deciduousforest, a desert, or a temperate grassland, such as a prairie orsavanna? In this lab, you will explore certain characteristics ofthe biome in which you live. With the information you gather,you will be able to identify which biome you live in.

Procedure1. Use a globe or atlas to determine the latitude at which you

live. Record this information.2. Consider the topography of the place where you live. Study

the contour lines on a map or surface variations on a globe.What clues do you find that might help identify your biome?For example, is your area located in near a mountain or anocean? Record your findings.

3. Prepare a climatogram of your local area. A climatogram is agraph that shows average monthly values for two factors:temperature and precipitation. Temperature is expressed indegrees Celsius and is plotted as a smooth curve. Precipitationvalues are given in centimeters and are plotted as a histogram.

To make a climatogram of your area, obtain monthlyaverages for one year of precipitation and temperature fromyour local TV or radio weather station. Make a data table,and record these values. Next, draw the vertical and hori-zontal axes of your climatogram in your notebook or ongraph paper. Then, show the temperature scale along thevertical axis on the right side of the graph and the precipita-tion scale along the vertical axis on the left side of thegraph. Show months of the year along the horizontal axis.Finally, plot your data.

Objectives� Collect information from interna-

tional, national, and local resourcesabout the biome in which you live.

� Performfield observations to identify thename of the biome in which you live.

Materialsbinoculars (optional)field guide to local flora and

faunaglobe or atlasgraph paper (optional)notebookpencil or penruler

USING SCIENTIFIC METHODS

Exploration Lab: FIELD ACTIVITYC H A P T E R 6

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� Climatograms The temperatureand precipitation for Austin, Texas isshown in this climatogram.


Chapter 6 Exploration Lab 169

4. Go outside to observe the plants growing in your area. Bringa field guide, and respond to the following items in yournotebook.a. Sketch or describe as many plants that are common in the

area as you can. Use your field guide to identify each ofthese species.

b. Describe three or more adaptations of each plant to thelocal climate.

c. Which of the plants that you observed are native to yourarea? Which have been introduced by humans? Which ofthe introduced plants can survive on their own in localconditions? Which of the introduced plants requireextensive human care to remain alive?

d. Look for evidence that animals have left behind—footprints, nests, dens or burrows, hair or feathers,scratches, or urine markings. Sketch or describe as manydifferent animal species as possible. Identify each speciesby using your field guide.

e. Describe three or more adaptations that each animal hasdeveloped in order to survive in local climatic conditions.

Analysis1. Analyzing Data Compare your local climatogram to the

biome climatograms shown in this chapter. Which biome hasa climatogram most similar to your climatogram?

2. Analyzing Results Consider your latitude, topographicalfindings, and observations of local plants and animals.Combine this information with your climatogram, and deter-mine which biome best matches the area in which you live.

Conclusions3. Evaluating Results Does your local climatogram match any of

the seven major terrestrial climatograms shown in the chapter?Explain how any differences between your local biome and thebiome in the chapter that your local biome most clearly matchesmight influence the adaptations of local animals and plants.

4. Applying Conclusions Organisms create features of thebiome in which they live. What features of your biome arecreated by the organisms that live there?

1. Classifying Information Name three adaptations youobserved in the plants that grow naturally in your area.Name at least three adaptations you observed in local ani-mals. Explain in detail how each of these adaptationsmeets the conditions of your biome.

Extension� Biomes These two cities are locatedin two different biomes. Stamford,Vermont (top) is located in a temper-ate deciduous forest, and Tucson,Arizona (bottom) is located in a desert.


THE FUTURE OF THE ARCTIC NATIONAL WILDLIFE REFUGE

170 Chapter 6 Points of View

During the 1970s, Congress passedthe Alaska National Interests LandConservation Act. The legislationgave Congress the responsibility fordetermining how Alaska’s landswill be used. Included in thisresponsibility is the fate of theArctic National Wildlife Refuge(ANWR). Oil company geologistsbelieve that oil reserves are underseveral areas of the northernAlaska coast, including the refuge.Debate has raged about whetherCongress should maintain ANWRas a wildlife refuge or open it to oilexploration. Advocates of therefuge feel that the environmentalcost of oil exploration would betoo high. But those who favor oilexploration in the refuge believethe oil reserves must be tapped tomeet U.S. oil needs and to maintaineconomic security.

Protect the RefugeConservationists and ecologists areconcerned about the impact that oilexploration would have on animalsthat live in the refuge. Oil explo-ration would occur within the 1.5million acre coastal plain of the

ANWR. This area includes thebreeding ground and grazing areafor one of the last great herds ofcaribou in North America.Biologists think that forcing theherd into other areas of the refugewould deprive the caribou of theirmain food source and would exposecalves to increased predation.

In addition, migratory birdsfrom all over the world travel tothe refuge’s tundra to nest andraise their young during the shortarctic summers. Scientists believethat oil exploration would disruptthe nesting and feeding of thesebirds so much that the birds wouldbe unable to finish rearing theiryoung before the first freeze ofearly September.

The ANWR is also a habitat formore than 7,000 native peoples.Some of these people depend on thecaribou of the ANWR for food,clothing, and tools. Oil explorationand drilling could displace the cari-bou population, which would dras-tically affect the culture and way oflife for these people.

Opponents of oil explorationin the refuge also point to the

environmental damage that hasalready been done in nearbyPrudhoe Bay. When oil was foundthere, oil companies joined forcesto extract the oil and built a pipe-line across the state to reachtankers on the southern Alaskacoast. Advocates of the refuge saythat the use of this pipeline hasexposed the fragile tundra ecosys-tem to toxic chemicals and de-stroyed natural habitats. They fearthe same fate for the refuge if oilexploration is permitted there.

Advocates of protecting therefuge also point out that no oneknows how much oil is availablein the refuge. They also point outthat even if all of the oil thatcould possibly be in the refugewere extracted, the oil would sup-ply the United States for only ninemonths.

Conservationists contend that thedevelopment and use of renewableenergy resources, such as wind andfuel cells, could reduce the depend-ence on oil. Laws that require stricterenergy conservation measures couldalso reduce the need for oil in theUnited States.

� Migratory birds, such as theCanada geese below, nest and raisetheir young on the refuge’s tundra.

� A small group of muskoxen huddles on the arctic tundra ofthe Arctic National Wildlife Refuge.


Chapter 6 Points of View 171

What Do You Think?Oil exploration in ANWR couldhave a negative impact on theanimals and people living inand around the refuge, but oilin the refuge may help the U.S.meet its future energy needs.Without knowing what theconsequences or benefits willbe, do you think that the U.S.should permanently protect theANWR or open it for oil explo-ration? Explain.

Open the RefugeAdvocates of oil exploration in theANWR believe that the current U.S.demand for oil cannot be met byenergy conservation alone. Advo-cates insist that the United Statesmust utilize every domestic sourceof oil available, including theANWR. The advocates also pointout that the United States dependstoo much on oil from other coun-tries that control its price and avail-ability. A significant amount of ouroil is imported from the MiddleEast, a politically unstable area. Ifthose countries restrict sales of oilto the United States, our economy

could be seriously affected. Thosewho favor exploration think eco-nomic security should take priorityover environmental concerns.

Advocates of oil exploration inthe refuge also stress that much ofthe oil in the Prudhoe Bay area hasalready been extracted and that oilproduction will soon begin todecline. The industrial complex thatis already in place for the produc-tion of oil in Prudhoe Bay could beused for the production of oil fromthe nearby refuge. New construc-tion in the area would be limited.

Because of the decline of oil inPrudhoe Bay, advocates support oil

drilling in the ANWR for economicreasons. The oil industry supportstwo-thirds of Alaska’s economyand employs 1 percent of the popu-lation. If the refuge were open fordrilling, oil companies would profitand more jobs might be availablefor the people of Alaska.

Government studies indicate a19 to 46 percent chance of findingoil in the refuge, which is a percent-age that the oil industry believesjustifies exploration. People whofavor exploration also suggest thatoil companies can now extract oilwith less environmental damagethan was caused in Prudhoe Bay.

People who oppose the protec-tion of the wildlife refuge believe theeconomic benefits of oil explorationin this area outweigh any remainingrisks of environmental damage.

� The pipeline shown above carries oil across the entire state of Alaska.

� Exploration for oil would occur in the northern coastal plain of the ArcticNational Wildlife Refuge.


section 3 grassland, desert, and tundra...

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