bioma

Biome Basics

Image © Addison-Wesley Publisihg Company.
A biome is an area on the earth's surface that has a certain set of characteristics. There are seven kinds of biomes in the world: tundra, taiga, temperate forest, tropical rainforest, desert, grassland, and ocean. The map above shows where each of these biomes can be found around the world. Although it does not appear in the key, the ocean is represented by the blue area on the map.

The Desert Biome
Deserts are places on earth that are characterized by little vegetation and rain. They are made up of sand or rocks and gravel. Deserts cover about one-fifth of all the land in the world. Most deserts lie along the Tropic of Cancer and Tropic of Capricorn, imaginary lines that lie north and south of the equator.
Oases are parts of the desert where plants grow and water is almost always available. An oasis is formed by a pool of water trapped between layers of rock beneath the desert floor. The regular water in an oasis allows people to settle in the desert and even grow crops.
Some deserts are named and nicknamed things like Death Valley, "the Empty Quarter," and "the Place from Where There is No Return" because of the lack of water there. Here are some interesting desert facts:
• The Gobi Desert in Asia is cold for most of the year.
• Mountains on the edge of deserts prevent rain from entering. The rain stays on the other side of the mountain creating rain forests next to many deserts. These deserts are called rain shadows.
• The world's deserts are growing through desertification. This happens when grasslands that border the desert become as dry as the desert. Desertification can also be caused by intense farming.
• Deserts are second only to tropical rain forests in the variety of plants and animals that live there.
The Grassland Biome
Grasslands are large areas with rolling hills of grasses and wildflowers. Grasslands are found on every continent but Antarctica. Sometimes grasslands are called prairies, savannahs, or steppes.
The roots of the grasses and small plants make the soil rich and great for farming. Some of the grasslands are used for animal grazing, too. The map below shows where grasslands are located around the world.
The Ocean Biome
Did you know that life on planet Earth began in the oceans more than 3 billion years ago?
Over 70 percent of the earth's surface is covered by water. In fact, when seen from space, our earth looks blue, because of the large bodies of water which cover most of it. Although we speak of separate oceans, the world is really covered by one huge ocean in which the continents are islands!
There are four main oceans: the PACIFIC, ATLANTIC, INDIAN, and ARCTIC.
The Rainforest Biome
The tropical rainforests of the world are located in the green areas on the map above. The tropical rainforest is the richest source of life on earth. It is a treasure chest of plant and animal life. What is a tropical rain forest? Where are they located? Why are they so important? You will learn the answers to these and many more exciting questions here.
The Taiga Biome
The taiga is the largest biome in the world. It covers large parts of Canada, Europe, and Asia. This forest is covered with coniferous trees. In fact, sometimes the taiga is called a coniferous forest.
Conifer trees are often called evergreens. These trees have long, waxy needles instead of wide, flat leaves like hardwood trees. Evergreens do not loose their needles come wintertime. The needles stay on all year long.

Temperate Forest Biome
Temperate forests are often called deciduous forests. In a temperate forest, most of the trees lose their leaves in the winter. During the fall, when the weather gets cooler, the trees begin to shut down. Their leaves turn beautiful shades of colors. Come winter time, the leaves fall off of the trees. Why do you think this is so?
The deciduous trees must lose their leaves, because water is not available for the leaves to survive. Also, the trees are not strong enough to keep their leaves and hold up all the snow that comes in the winter.
The Tundra Biome
The tundra is located around the North Pole in the Arctic Circle. For most of the year it is covered in snow. In the short summers, the snow and ice melt to leave pools of meltwater. The layer of earth beneath the tundra is frozen all year long. This is called the permafrost. Industrial activity in the tundra may add to the world's environmental problems. Dust and grime make the ice darker, so less heat is reflected from the ice and global warming is increased.