A biome is a large area having a distinct climate and specific types of plant and
animal life. At the top of the world lies the polar ice cap. There is no land
underneath the ice. Traveling south from the polar ice, the first land you come
to is part of the tundra biome. The tundra is lonely, windy, and cold. The tundra
covers the northern parts of North America, Europe, and Asia. In North
America, tundra stretches from the Arctic Ocean south to the middle of Canada.
The arctic tundra has a cold, dry, harsh climate. From September through May
the tundra is locked in winter's icy grip. The ground is frozen as hard as stone.
Snow, driven by howling winds, sweeps across the land. Very little
precipitation falls there; most of it is snow. Tundra animals must endure long,
bitterly cold winters. Winter days are short. The nights are very long. For many
weeks in the middle of winter, the sun doesn't come up at all. It is dark for twenty-four hours a day.
Tundra summers last just three months from June through August. But summer days on the tundra are long and
sunny. The sun shines both day and night. In summer, temperatures may get above fifty degrees F. But frost is still
possible in July.
At the beginning of the summer, sunshine and warmer temperatures melt the snow that winter left behind. But
because summer is so short, only the top few inches of soil thaw out. Deeper down, the ground never thaws. This
ground that is always frozen is called permafrost.
In the summer, the ground is squishy because of the permafrost. Since only a few inches of soil are not frozen
solid, water can't soak into the ground. The water collects in low spots. There it forms shallow lakes and ponds.
Parts of the tundra are dotted with these pools of water for most of the summer. Yet it rarely rains, so on higher
ground, the soil can get very dry.
The soil is thin and poor. Most tundra plants have shallow roots. Roots can't grow into permafrost. Tundra plants
hug the ground to escape the fierce winds. They form a dense mat that covers the land like a thick carpet. Few of
the plants grow more than knee-high.
Many different kinds of plants grow on the tundra. They are all crowded together. Most have small leaves that are
tough and leathery. Small leaves stand up to cold and wind better than large leaves do. Some leaves are covered
with soft little "hairs." These tiny hair-like structures trap water. They help keep tundra plants from drying out.
Lichens grow on the ground and on rocks. Lichens are very tough. They can survive in the coldest, driest places
where nothing else can grow.
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Because the summers are short, tundra plants must hurry to grow. As soon as the snow begins to melt at the end of
winter, green shoots pop up. They sprout from seeds or roots that survive the long cold months under snow. As
flowers begin to bloom, the tundra explodes with color. The plants must flower and make seeds before winter
returns. Small shrubs grow on the tundra, too. They don't die back to the ground at the end of summer like flowers
do. Instead, their woody stems grow a little bit each year. Some of these small shrubs may be fifty years old!
Polar bears live along the tundra's edges, where the land meets the icy sea. Polar bears spend most of their time
near the water hunting for seals, their favorite food. Mammals of the tundra also include caribou, musk oxen,
lemmings, foxes, wolves, and hares.
Every year when the snow begins to melt, other animals arrive. These summer visitors move up from the south to
spend the summer on the tundra. Swarms of black flies and mosquitoes provide food for many birds. When winter
approaches, most birds migrate south to warmer climates.
The tundra is like a cold, wintry desert. Few animals live there year-round. Plants are small and have shallow root
systems. Winters are long with many hours of darkness. Summers are short with long hours of daylight. Winters
may be as cold as thirty degrees below zero, while summer highs are usually in the fifties. Tundra life is hard for
animals and plants. Organisms that live in the tundra have adapted to the harsh conditions.
1)How many of these can you write about? Think! Write! Check all the ones you answered.
Describe what winter conditions are like in the tundra. What animals stay all winter?
Describe summer conditions in the tundra. What animals would you see?
IT HAS TO BE AT LEAST 2 PARAGRAPHS
Answers
A biome is an area of the planet that can be classified according to the plants and animals that live in it. Temperature, soil, and the amount of light and water help determine what life exists in a biome.
A biome is different from an ecosystem. An ecosystem is the interaction of living and nonliving things in an environment. A biome is a specific geographic area notable for the species living there. A biome can be made up of many ecosystems. For example, an aquatic biome can contain ecosystems such as coral reefs and kelp forests.
Not all scientists classify biomes in the same way. Some use broad classifications and count as few as six biomes. These are forest, grassland, freshwater, marine, desert, and tundra.
Other scientists use more precise classifications and list dozens of different biomes. For example, they consider different kinds of forests to be different biomes. Tropical rain forests that are warm and wet year-round are one biome. Temperate deciduous forests—those that have cold winters, warm summers, and are dominated by trees that lose their leaves—are a different biome. Taiga forests, which are in cold regions and are dominated by cone-bearing firs and spruces, are yet another biome.
Boundaries between biomes are not always sharply defined. For instance, there are sometimes transition zones between grassland and forest biomes. Coasts and wetlands are transition zones between terrestrial and aquatic biomes.
Biomes move as the climate changes. Ten thousand years ago, parts of North Africa were lush landscapes cut by flowing rivers. Hippopotamuses, giraffes, and crocodiles lived amid abundant trees. Gradually, the climate dried out. Today, this region is part of the Sahara Desert, the world's largest desert.