Britannica Student Encyclopedia - 2010

every living

thing.

BRITANNICA STUDENT ENCYCLOPEDIA Biome 73

 

survival. These smaller areas are called

ecosystems. Each biome has many ecosystems.

Tundras

The tundra biome is found in extreme

northern regions. This biome has cold,

dry conditions. The main plants include

mosses, lichens, and short grasses. Arctic

foxes, reindeer, and migrating birds are

some common tundra animals.

Forests

Trees are the main plants in forest

biomes. There are several different types

of forest biome.

The taiga is a conifer forest biome. It lies

just south of the tundra biome. The

taiga has long, cold winters and short,

mild summers. It gets more rain than

tundras do, so it can support conifers.

Conifers are trees with needles, such as

spruces and firs. Lynx, timber wolves,

moose, and beavers live in this biome.

Deciduous forests are found mainly in

the Northern Hemisphere. This biome

has cold winters and warm summers.

The trees are deciduous, meaning that

they shed their leaves in the fall. Deer,

bears, bobcats, and squirrels are common

to this biome.

Tropical rain forests lie near the equator.

This biome has hot, wet conditions all

year long. Tall, tropical trees and many

other plants grow there. Monkeys, parrots,

and anaconda snakes are some of

the many rain forest animals.

Grasslands

Grassland biomes are places that get

enough rain for grasses to grow but not

enough to support forests. Temperate

grasslands have hot summers and cold

winters. Tropical grasslands, also known

as savannas, are hot all year long. Prairie

dogs and mule deer live in the temperate

grasslands of North America. Giraffes,

zebras, and lions live in the tropical

grasslands of Africa.

Not all deserts

are hot. A

cold desert

covers part of

Antarctica.

74 Biome BRITANNICA STUDENT ENCYCLOPEDIA

 

Deserts

Deserts are the driest biome. The largest

desert, the Sahara, is in northern Africa.

Deserts receive less than 10 inches (25

centimeters) of rain each year. Cacti and

creosote bushes are two types of plant

that can survive the dry conditions.

Rattlesnakes, lizards, roadrunners, and

owls are some of the animals of this

biome.

#More to explore

Desert • Ecology • Forest • Grassland

• Rain Forest • Taiga • Tundra

Birch

The trees called birches have long been

known for their beautiful bark. Native

Americans used birch bark to make

canoes, tepees, and moccasins. Today

people use birch wood to make

furniture, flooring, and plywood.

Birches are also planted in parks and

gardens.

Birch trees are found in the northern

half of the world. They grow in areas

with cool to cold weather.

There are about 60 species, or types, of

birch. Some birches are shrubs, but most

are trees. The monarch birch of Japan is

one of the tallest birches. It grows to 100

feet (30 meters). Many birch trees in the

United States are 40 to 70 feet (12 to 21

meters) tall. Birches have narrow trunks.

Their bark is often white, and it has

lines that go from side to side. Most

young birch trees have bark that is easy

to peel off.

Birch leaves are usually bright green.

They turn golden yellow in the fall.

Clusters of flowers grow on birches.

They are called catkins. Some catkins

look like miniature pinecones. These

cones hold seeds. When the cone falls

apart, the seeds scatter.

Birches can reproduce in several ways.

Some birches grow from seeds. Others

sprout from birch trunks or birch roots.

#More to explore

Bark • Tree

Scientists in England created a humid tropical

biome under a dome. It was part of a

project to teach people about the relationships

between plants and amimals.

Birch trees are known for their white bark.

BRITANNICA STUDENT ENCYCLOPEDIA Birch 75

 

Bird

From pigeons in big cities to penguins

in Antarctica, all birds have similar features.

They all have wings, though they

cannot all fly. All birds also have feathers.

In fact, birds are the only living animals

that have feathers.

Birds have fascinated people throughout

history. Many people keep birds as pets

or enjoy watching them in the wild or at

zoos. In addition, farmers raise poultry

for their meat and eggs. Hunters shoot

some birds as game. People also use bird

feathers in various products and for

decoration.

Where Birds Live

Birds are found almost everywhere on

Earth. There are more than 9,000 species,

or types, alive today. Different types

of bird have adapted to different habitats,

from deserts to rain forests to icy

lands to cities.

Many birds migrate, or fly long distances

between their winter and summer

homes. For example, many European

birds travel to Africa for the winter. This

helps them find enough food yearround.

Physical Features

Birds are warm-blooded. This means

that their body temperature stays about

the same, regardless of the temperature

of their surroundings. Mammals,

including humans, are also warmblooded.

However, birds are more

closely related to the group of coldblooded

animals called reptiles than they

are to mammals. In fact, many scientists

think that birds developed from dinosaurs,

which were reptiles, millions of

years ago.

Size and Color

Birds vary greatly in size. The bee hummingbird

is the smallest living bird. It is

only about 2.5 inches (6.3 centimeters)