life in the biosphere

Vocabulary abiotic factors adaptation biome biotic factors community ecosystem environment population Picture Credits Every effort has been made to secure permission and provide appropri

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Scott Foresman Science 6.6

Nonfi ction Main Idea and Details • Captions

• Diagrams

• Glossary

Biomes

ISBN 0-328-13986-6

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Scott Foresman Science 6.6

Nonfi ction Main Idea and Details • Captions

• Diagrams

• Glossary

Biomes

ISBN 0-328-13986-6

ì<(sk$m)=bdjigg< +^-Ä-U-Ä-U

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1 How does a population differ from a community

within an ecosystem?

2 Why are organisms in a biome similar even if they

live many thousands of miles apart?

3 How does the canopy of a dense forest affect the

plants on the fl oor of the forest?

4 One way that plants adapt to

different conditions is their shape Write to explain how climate can affect the shape of the main plants in a biome Include details from the book to support your answer

5 Main Idea and Details Make a graphic

organizer Complete the details that support this main idea: A population is a group of individuals

of the same species that live in an area

What did you learn?

Vocabulary

abiotic factors

adaptation

biome

biotic factors

community

ecosystem

environment

population

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.

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1 Digital Stock; 2 (B) Getty Images; 4 (B) Getty Images, (T) Getty Images; 6 (B) Getty Images;

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11 (T) Brand X Pictures; 12 (B) Getty Images; 13 (T) Getty Images, (BR) Digital Vision; 14 (B) Getty Images;

15 (R) Getty Images; 16 Getty Images.

Scott Foresman/Dorling Kindersley would also like to thank: Opener: (C) ©Jerry Young/DK Images;

12 (BC) ©Jerry Young/DK Images; 15 (BC) ©Jerry Young/DK Images.

ISBN: 0-328-13986-6

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,

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

by Steve Miller

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How are organisms on

Earth connected?

The biosphere is the part of Earth where living things are

found The whole land surface of the planet is part of the

biosphere It also includes the atmosphere to about ten kilometers

high and the oceans, from the surface to the deepest parts, eleven

kilometers below the surface No matter how cold or hot, wet or

dry, there are living things in all these places

All these organisms—plants, animals, and bacteria—share

resources such as light, water, and air As a result, life on the

planet is connected When something happens to one living thing,

it affects those around it The science called ecology studies how

living things affect one another

The biosphere includes all living things—even the people who live in this city.

Connections in the Biosphere

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Organization of the Biosphere

What did you do before school today? Maybe you ate an apple, played with your baby sister, or drank a glass of water Each

of these activities is an interaction with something or someone else Everything that you do, even breathing the air, affects things around you, and they affect you The things around you make up

your environment An organism’s environment is anything that

can affect it This includes living things, such as trees and plants, or any pet you might have It also includes nonliving things, such as water and air

Within an environment, there can be many different

organisms of one species A population is a group of individuals

of the same species that live in one area The frogs in the picture make up a population The dragonfl ies are another population

If there were two kinds of frogs, they would make two different populations That is because they are different species There is also a population of each kind of plant and each species of fi sh in the pond

How do the populations

of frogs and dragonfl ies interact with one another?

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In an environment, many different populations live together

A community is a group of populations that interact with each

other in an area A pond community includes frogs, dragonfl ies,

other insects, and fi sh It also includes all the plants that provide

food and shelter for these animals Some parts of the community

are hidden, such as bacteria that are too small to see These

living things affect one another Some are food for others Some

compete for the same resources For example, frogs and lizards

may both eat the same insects

Communities of organisms also rely on nonliving parts of the

environment for many of their needs Each organism has needs

for air, water, minerals, and shelter The entire community of

living things, along with the nonliving parts of the environment,

is called an ecosystem An ecosystem can be very small The

plants and animals in the terrarium are part of a tiny ecosystem

They interact with one another and with the air, water, and rocks

Other ecosystems are very large These bison and the grasses they

eat are part of a prairie ecosystem that once covered much of

North America

The population of bison needs

the prairie grasses for food.

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The Needs of Organisms

The organisms that live in an ecosystem are called the biotic

factors In the prairie, the biotic factors include the bison and

other animals The grasses and wildfl owers provide food for the bison, many of the birds, and small prairie animals, such as mice

Although you cannot see them in the picture, microorganisms, such as bacteria, live in all parts of the ecosystem Some of the microorganisms live inside the bison’s digestive system They are also biotic factors of this ecosystem

Living things provide for many of the needs of plants and animals Other needs are provided for by the nonliving part of

the environment, called the abiotic factors These include water,

air, sunlight, and even temperature All these factors affect what types of organisms can survive in the ecosystem

A terrarium is an ecosystem because it has a community of living things.

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What are Earth’s

biomes?

Certain kinds of large ecosystems occur at different places

around the world The plants and animals of the Mohave Desert

in the southwestern United States look a lot like those in the

deserts of northern Africa and central China This is because the

climates of those regions are similar—very dry with hot days All

these desert ecosystems are similar A biome is a large group of

ecosystems with similar climates and organisms The Mohave is

part of the desert biome This map shows the locations of some

of the major biomes on Earth

Climate and Biomes

Deciduous forests are located

in the Northern Hemisphere

between the hot tropics and

cold polar regions These

forests have warm

summers and cold

winters.

Grasslands are

found on every

continent except

Antarctica Large grazing

animals live in herds in

many grasslands.

7

tundra

Taiga is the evergreen forests that cover much

of the northern parts of North America, Europe, and Asia The taiga plants and animals are adapted

to survive short summers and long, cold winters.

Tundra is the biome in the Arctic areas where the growing season is too short for trees Tundra temperatures are cool in summer and very cold in winter Below the surface

of the ground is a layer of soil that never thaws.

Rain forests are located near the equator

They have warm, wet climates and a year-round growing season

In many rain forests, the temperature always stays above the freezing point of water.

Deserts are ecosystems that receive less than 25 cm of rainfall each year Many desert plants grow very quickly after a rainfall and then stay dormant for months until the next rain.

A biome is not one specifi c area It consists of ecosystems from different parts of the world that have similar climates and organisms.

rain forest grassland desert taiga deciduous forest mountainous areas polar regions

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Why are the plants and animals in a biome similar, even if

they are on different continents? Organisms have features that suit

the biotic and abiotic factors of an ecosystem In places that have

similar climates, the abiotic factors are often quite similar The

plants and animals also have similar adaptations An adaptation

is a characteristic that helps an organism live and reproduce in

an environment

The two plants on this page have adaptations to help them

survive in similar environments You may be familiar with cactus

plants, such as the saguaro cactus shown here Cactuses are found

in many parts of North and South America Adaptations help

them survive in an environment that has high temperatures and

very little water The saguaro has soft, wet tissues full of water,

and a thick skin to hold the water in the plant There is very little

rain in the desert, so the plants grow slowly The spines on the

cactus protect it from hungry animals Now look at the picture of

the euphorbia plant It looks a lot like the saguaro cactus It has

soft, moist tissues, a thick skin, and protective spines However,

the euphorbia grows in Africa and is not a very close relative of

the cactus plant The two plants show similar adaptations to the

hot, dry climate of their biomes

The saguaro cactus has adapted to an

environment with very little water.

Adaptation

Although they look similar, this euphorbia

is not a close relative of the cactus.

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Characteristics of Biomes

Climate is one factor that determines what types of organisms live in a particular place In warm areas with a lot of rain, plants grow very quickly Because there are a lot of leaves to provide food and shelter, there are usually a lot of animals as well The tropical rain forests have many more species than other biomes Most of these species would not be able to survive in cold climates They might do well in a different rain forest, though Their adaptations suit a particular biome

Even though the ecosystems within a biome are similar, they are not exactly alike These elephants live in the grasslands of Kenya in Africa You can tell at a glance that they are different from the bison you saw before The bison have long fur to protect them from the cold winters on the American plains The elephants,

on the other hand, have very little hair because the temperature rarely drops below freezing in the grasslands of Kenya

Like bison, elephants live in a grassland biome.

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The living things in the deciduous forests have adaptations that suit cold winters and hot, rainy summers The trees have wide leaves that gather lots of light during the growing season The plants that grow on the forest fl oor must adapt to less sunlight because of the shade from the trees As cold weather and shorter days approach, the trees stop producing food

The leaves change color and then fall The

fl oor of a deciduous forest is covered with rich soil produced by decaying leaves The leaves and soil provide food and shelter for many species of plants and animals

Many insects and caterpillars feed on the nutritious leaves of the trees They become food for other animals, such as spiders, toads, moles, and birds Larger animals that are common in this biome include skunks, raccoons, coyotes, deer, and bears Because there is less food in the winter, some of the animals of the forest hibernate Others, especially birds, migrate—that is, they move to places with

a warmer climate—until spring

slug

Deciduous Forests

If these trees did not lose

their leaves in winter, the

weight of the snow could

break the branches

The decaying leaves are

home to many species

of animals and plants

earthworm

centipede

Taiga Because of the shape of these trees, snow falls off them.

The taiga, or coniferous forest, covers areas of Alaska, Canada, northern Europe, and Russia These forests have evergreen trees, such as pine, spruce, and fi r, which stay green all year long This is an adaptation for short growing seasons Too much energy would be lost if the trees had to make new leaves every spring

Most of the trees of the taiga produce nutlike seeds in cones

The seeds feed insects, birds, and small mammals, such as squirrels and mice Because the climate is wet, there are plenty of places for insects to live Many kinds of insect-eating birds live in this forest

Many of the birds migrate to warmer areas in winter Other animals are adapted to the cold winters Some of the

small mammals burrow underground to escape the cold Others, such as brown bears and bats, hibernate through the winter, surviving by using fat stored in their bodies from the summer Wolves, mink, and grizzly bears have thick winter coats, and they hunt other animals even in very cold weather

The dormouse becomes fat in the summer and autumn, and hibernates

in the winter.

11

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The living things in tropical rain forests have adaptations for

hot, wet weather This biome is located all around the world near

the equator Plants grow all year in the rain forest and don’t lose

their leaves in winter

The tropical rain forest grows in layers Giant trees grow

about seventy-fi ve meters tall Their leaves form a dense cover,

called the canopy, which absorbs most of the light from the Sun

Thick vines climb up the trunks of the trees into the canopy and

compete with the trees for sunlight Below the canopy is a middle

layer of vines, smaller trees, ferns, and palms Many of these

plants have huge leaves to capture as much light as possible

An amazing number of plants and animals live in the rain

forest Some of them spend their whole lives in one tree Because

the climate is mild, there are many birds, reptiles, and amphibians

There are so many species in the rain forests around the world

that scientists are constantly discovering new ones

Rain Forests

The rain forest grows

in layers of plants competing for sunlight.

Many reptiles and amphibians have adaptations that suit the hot, wet climate of the rain forest.

12

Grasslands

Grasslands are generally fl at, open areas that get some rain, but not enough for large trees There are grasslands on every continent except Antarctica Grasses have deep roots, an adaptation that helps them survive the low amounts of rainfall in these areas

The height of the grass ranges from twenty centimeters to over two meters Many roots extend more than two meters below the surface During long dry periods or cold winters, the part of the grass plant above ground dies, but the deep roots are protected in the soil When conditions are right, the grass begins to grow again

The grasslands generally have good soil and produce a large amount of grasses and

other fl owering plants Many animals graze in these open lands

Grasslands are home to many large animals, such as bison, elephants, rhinos, and antelope Many smaller mammals tunnel in the ground among the grass roots Predators, including lions, panthers, owls, and hawks, hunt in the grass

Many animals, such as these meerkats,

fi nd shelter in underground burrows.

When there is little rain, the grass above ground dies, but the deep roots are ready for the next rainy season.

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The key characteristic of the desert biome is that it is very

dry People often think of deserts as hot, but any area that gets

little rain is a desert, even parts of Antarctica Desert plants have

adaptations that help them survive with little water In general,

they are small, compared to plants in other biomes, and they grow

slowly In the Americas, many desert plants are cactuses Similar

plants grow in other deserts

In hot deserts, animals are usually active at night, when the

temperature is much lower Because there is a limited amount

of shelter and food, there are not many large animals in deserts

Small mammals, snakes, lizards, and spiders are found in hot

deserts Many animals burrow under the ground where it is

cooler during the day

Because there is so little rain, deserts do not have a canopy Leaves are small and thick to save moisture.

Many of the small mammals that live in the desert come out at night when it is cooler This owl’s excellent vision and hearing help it fi nd the animals it hunts for food.

Tundra

Some tundra animals, such as this fox, have white winter coats that make them hard

to see on the snowy tundra.

The tundra is a biome that combines cold temperatures, a short growing season, and limited water Most of Earth’s organisms could not survive there The tundra surrounds the Arctic, north of the taiga Just below the surface

is a permanently frozen soil layer called permafrost When the top layer thaws in summer, water from the melted ice stays close to the surface Although the growing season is short—two to four months—

there are plants that grow in the tundra

Short bushes and shrubs, mosses, and grasses are the most common plants

Animals that live in the tundra have adaptations that help them survive in cold, windy conditions Most birds migrate when temperatures grow too cold for the insects that they eat Many small mammals survive by eating the tundra plants Larger herbivores such as caribou and reindeer move across large distances looking for food Foxes and wolves prey

on these animals, and polar bears catch seals and other marine animals for food

Like the desert, the tundra has little water Plants must also adapt

to extremely cold winters.

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Glossary

abiotic factors nonliving parts of an ecosystem, such as air,

water, or minerals

adaptation a characteristic that helps an organism to survive

in an environment

biome a large group of ecosystems that have similar

climates and organisms

biotic factors the living parts of an ecosystem, such as plants,

animals, and bacteria

community a group of populations of living organisms that

live and interact in an area

ecosystem an entire community of organisms as well as the

nonliving things with which they interact

environment the things that affect an organism

population the organisms of one species that live and

interact in an area