5 6 changing world (life science)

5.1 The Cat Family (Life Science) 5.2 Inside Sea Creatures (Life Science) 5.3 Staying Healthy (Life Science) 5.4 Food and Farming (Life Science) 5.5 Build an Aquarium (Life Science) 5.6 Changing World (Life Science) 5.7 Underwater Explorers (Earth Science) 5.8 Drought (Earth Science) 5.9 Mountains of the World (Earth Science) 5.10 Green Gardening (Earth Science) 5.11 Pioneers of Physics (Physical Science) 5.12 Baking Chemistry (Physical Science) 5.13 Building Science (Physical Science) 5.14 Generating Power (Physical Science) 5.15 The Light Bulb (Physical Science) 5.16 Telescopes (Space and Technology) 5.17 Moon Landings (Space and Technology) 5.18 Cars Present, Past, and Future (Space and Technology)

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Scott Foresman Science 5.6

Nonfi ction Cause and Effect • Labels

• Captions

• Sidebars

• Glossary

Changing Ecosystems

ISBN 0-328-13933-5 ì<(sk$m)=bdjdda< +^-Ä-U-Ä-U

Scott Foresman Science 5.6

Nonfi ction Cause and Effect • Labels

• Captions

• Sidebars

• Glossary

Changing Ecosystems

ISBN 0-328-13933-5 ì<(sk$m)=bdjdda< +^-Ä-U-Ä-U

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1 Why are animals becoming endangered?

2 How do farms affect ecosystems?

3 What are some ways waterways can become

polluted?

fl owered plant brought to the United States from Europe in the 1800s It does not have any natural enemies in its new habitat and has spread throughout forty-nine of the fi fty states What consequences do you think this has on its new ecosystem? Write to explain your answer Use information from this book

to support your ideas

5 Cause and Effect Name a cause and

effect of habitat loss

What did you learn?

Extended Vocabulary

acid rain bedrock deforestation drought endangered fossil fuels herbivore thermal pollution

Vocabulary

behavioral adaptation

extinct

inherit

mutation

pesticide

structural adaptation

Picture Credits

Every effort has been made to secure permission and provide appropriate credit for photographic material

The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions.

Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd).

8 (TR) Andre Maslennikov/Peter Arnold, Inc.; 14 Andrew Brown; Ecoscene/Corbis.

Scott Foresman/Dorling Kindersley would also like to thank: 1 NASA/DK Images.

ISBN: 0-328-13933-5

This publication is protected by Copyright, and permission should be obtained from the publisher prior to any

prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic,

mechanical, photocopying, recording, or likewise For information regarding permission(s), write to

Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.

3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05

by Natalie Rompella

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There are many factors that affect ecosystems Animals

can change ecosystems in both positive and negative ways

Earthworms help by adding oxygen and nutrients to the soil

Insects, such as swarms of locusts, can cause major damage

to crops People change ecosystems too Over time, people

have moved plants and animals from their native ecosystems

to new ones Sometimes this changes the food chain of

the ecosystem or takes away space from the native plants

and animals

The plants and animals in ecosystems can also adapt

over time Genes are passed down from each parent to their

offspring and control such things as eye color and weight

Offspring will often resemble one or both of their parents

The ecosystem can even have an effect on what an organism

looks like The color of fl amingos, for instance, is a result

of their diet The kind of soil some fl owers grow in can

affect their color

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What You Already Know

Earthworms add nutrients and oxygen to soil.

A mutation sometimes occurs in the genes that are passed down This change may end up helping the organism, for example, by making it blend in better with its surroundings

Or it may harm the organism by making it more prone to disease Or the change may be neutral If this mutation helps the organism adapt, it has a better chance for survival

Some adaptations are structural adaptations They are a change to a body part that helps the organism survive better

Behavioral adaptations, also called instincts, are changes

in behavior that help creatures survive Offspring inherit these adaptations from their parents

If a species does not adapt to changes in its ecosystem,

it may become extinct When this happens the species will never return

Can you guess what causes ecosystems to change more quickly than anything else? The answer may surprise you:

it’s humans Keep reading to learn what kind of impact people are having on

their environment

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A tiger’s stripes are

an adaptation that helps it blend into its surroundings.

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Our world is constantly changing One change to an

ecosystem can have many consequences for its inhabitants

Some changes have natural causes, such as hurricanes and

tornadoes People, however, can also change ecosystems Our

actions can affect the habitats of plants and animals Over

time our technology has caused drastic change to our world

In Europe during the 1760s, people began using machines

to do work Tasks that were once done by humans or with

the help of animals were suddenly being done in less time

with the help of machines Coal was the main power source

But it made thick, black smoke, which clouded the air

Factories produced wastes that polluted streams, rivers,

and lakes

Advances in technology soon spread across the world

Better medical care allowed populations to grow More

farms were needed to feed the increasing numbers of people

Trees were cut down to make room for corn and rice fi elds

as farms grew and grew Animals that once relied on the

forests lost their homes

People still change ecosystems For example, power

stations, automobiles, and pesticides used by people cause

pollution Populations are growing faster than ever, requiring

more land to be cleared for farming Read on to learn more

about how people’s actions affect ecosystems and the plants

and animals that live in them

Introduction

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Acid rain affects trees by damaging their leaves and polluting the soil that gives them nutrients.

Power stations burn fossil fuels that pollute the air.

Pesticides and fertilizers from farms can end up in nearby waterways, affecting the aquatic life.

Ships that carry oil sometimes leak or spill, causing the oil to end

up in waterways.

Fumes from industry and automobile exhaust are higher in cities than rural areas

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Why doesn’t a polar bear get cold in the Arctic? How

does a cactus survive in the desert without much water?

Plants and animals have adapted to survive in a wide range

of habitats Many animals in the Arctic, for instance, have

layers of blubber and thick fur to help them stay warm in

the extreme cold Desert plants, such as cactuses, are able to

live without much water They also absorb rainwater quickly

and are able to store it for droughts, which are times when

less water than normal is available

Unfortunately, sometimes habitats are changed so much

that it is hard for plants and animals to adapt Many times,

humans cause these changes

Changing Habitats

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Deforestation has caused many animals and plants

to lose their homes.

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Around the world, large numbers

of trees are cut down by humans

This is called deforestation

Sometimes the wood is needed

to make products such as lumber and paper Other times, trees are cut down to clear the land for farming or building Many animals use the trees for homes or hide in them

to escape predators

A similar problem is happening

in the rainforests, where there is a wide variety of plants and animals

Animals rely on the plants for food and shelter Humans also rely on many of the plants for medicines, food, and other products

Even in the ocean, habitats are being destroyed Coral reefs are a special saltwater habitat created by coral, an unusual animal related to the jellyfi sh Coral reefs are home to many different ocean plants and animals Pollution and higher sea temperatures are hurting coral populations This affects not only the coral, but all of the other animals and the plants that live there

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The saguaro cactus adapts well to its dry desert habitat.

Coral reefs face threats from pollution and warmer temperatures.

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Since industry fi rst began,

pollution has been a problem

Factories and power stations need

fuel in order to produce energy

Many run on fossil fuels, such

as coal, oil, or natural gas When

burned, these fuels can cause

air pollution This can result

in acid rain, which contaminates

water Acid rain can cause damage

to the outsides of buildings and be

unhealthy for animals to drink Acid

rain seeps down into the soil too

This can cause the acidity of the soil

to change Then aluminum may be

released into lakes and rivers

Aluminum is very dangerous

for fi sh and other marine

animals It can also hurt the

predators of these animals

Effects of Industry

8

Acid rain can make trees unhealthy.

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Some factories and power stations also produce unwanted heat They reduce this heat with cold water and then pump the water into rivers This can cause serious problems for the environment The river water becomes heated, which reduces the amount of oxygen it can hold This is called thermal pollution Marine species such

as fi sh need a certain amount of oxygen in the water Without it they can die Animals that eat

fi sh are, in turn, affected if there is less food

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Power stations can cause acid rain or thermal pollution.

Adaptation

Most peppered moths used to be gray, to blend in with the light-colored trees where they lived Then humans polluted the environment, turning the trees black Black moths became more successful, because they blended in better with the black trees

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How can farming affect ecosystems? Herding of animals

and plowing can result in soil erosion Soil erodes when its

protective, top layer, called topsoil, is worn away Without

topsoil, plants can’t grow With no plants or topsoil, any

fertilizer that farmers use gets washed into nearby lakes and

rivers by rain The fertilizers cause large amounts of algae

to grow in the water The algae use up the oxygen that other

living things in the water need to survive

Effects of Farming

Normally, plants help to keep

the nutrients in the soil.

Topsoil is a protective top

layer of soil where plants

grow It is rich in nutrients

and helpful organisms, such

as earthworms.

Bedrock particles make the

layer below the subsoil rocky.

The bedrock layer is made of

hard stone.

Subsoil is not as rich in nutrients

as the topsoil above it It

contains more clay and salts.

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Clearing land for farming can also destroy habitats Many times, trees and other plants are removed to make way for farmland Both may have been used by animals for food or shelter If herbivores do not have plants to eat and cannot survive, neither can the animals that eat the herbivores Even butterfl ies rely on plants for survival If the plants are taken away, they are not able to lay eggs

Prairie dogs can lose their homes because of farming.

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Plows are used on farms to break up the soil Overplowing, however, can cause the soil to erode.

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What do the giant panda, the whooping crane, and the

white-whiskered spider monkey all have in common? All

are endangered animals that have lost their habitats due to

farming or deforestation If an animal’s habitat is destroyed,

the animal loses its home and food source The tapir is an

endangered animal found in Asia It has lost its habitat

because of farming, logging, and mining The golden lion

tamarin, a kind of monkey, has had its forests cut down for

lumber and charcoal, and to make room for plantations,

ranches, and farms Another reason tamarins are endangered

is that they are captured for zoos and pet stores

Endangered!

tapir

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New Zealand was home

to the tuatara, a reptile, for millions of years Humans, however, introduced rats, wild cats, and pigs to the islands

This had disturbing effects on the tuatara Its eggs and young were eaten and there was more competition for food The tuatara is now only found on thirty of New Zealand’s small, offshore islands

The Dodo

Humans discovered the dodo bird about four hundred years ago and drove it to extinction

in under one hundred years This was due

to deforestation,

as well as the introduction of cats, rats, and pigs to the dodo’s island habitat.

golden lion tamarin

tuatara

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Humans are learning the effects of not taking good care

of our planet Over the years, organizations have worked to

help educate people and protect ecosystems

The World Wildlife Fund (WWF) is an organization

that helps to protect endangered animals from becoming

extinct and works to preserve their habitats The WWF

has been working for this cause for more than forty years

Solutions

14

Making a Return

Many animal populations that

were once close to extinction

are now growing again Through

protection and controlled

breeding, the Arabian oryx has

been reintroduced to its original

habitat in Saudi Arabia The

European bison had gotten to

the point of extinction in the wild

due to deforestation With the

help of scientists, the European

bison has been brought back

to the woods and grasslands

of Western Europe

Arabian oryx

bison

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The Environmental Protection Agency (EPA) works

to make sure that humans are creating a healthy, safe environment, not only for plants and animals, but also for themselves The EPA makes sure that environmental laws are

in place and that they are followed Some laws keep factories from dumping wastes into rivers, lakes, or oceans

What can you do to make a difference? Right now, what you buy can help the environment Try to buy things that don’t have much extra packaging, which becomes waste

When you grow up, you can vote for leaders who will pass laws to protect the environment

Thanks to all of the efforts to help our planet, many plants and animals are being taken off the endangered list

Streams are becoming clean again Trees are being replaced and animals are returning home

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Plastic tubing shelters young trees.

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Glossary

trees, for lumber or to make room for factories, farms, and homes

deep in the ground from ancient plants and animals

thermal pollution the overheating of water, which

affects marine life

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