Conclusion

As we can see all the world is covered by different biomes. The biomes are caracterized by the type of climate and the animals that habitate in it. All the biomes are importante for the society so we need to conserve them. For the past years human activities have altered these comunities. we can help by advising to other persons who important biomes are and who we are destroying them.

The tundra biome

Tundra along the Colville River, Alaska. Tundra is the coldest of all the biomes. Tundra comes from the Finnish word tunturi, meaning treeless plain. It is noted for its frost-molded landscapes, extremely low temperatures, little precipitation, poor nutrients, and short growing seasons. Dead organic material functions as a nutrient pool. The two major nutrients are nitrogen and phosphorus. Nitrogen is created by biological fixation, and phosphorus is created by precipitation.
Characteristics of tundra include:
Extremely cold climate
Low biotic diversity
Simple vegetation structure
Limitation of drainage
Short season of growth and reproduction
Energy and nutrients in the form of dead organic material
Large population oscillations
Tundra is separated into two types:
Arctic tundra
Alpine tundra

The grassland biome

A grassland west of Coalinga, California. Grasslands are characterized as lands dominated by grasses rather than large shrubs or trees. In the Miocene and Pliocene Epochs, which spanned a period of about 25 million years, mountains rose in western North America and created a continental climate favorable to grasslands. Ancient forests declined and grasslands became widespread. Following the Pleistocene Ice Ages, grasslands expanded in range as hotter and drier climates prevailed worldwide. There are two main divisions of grasslands:
Tropical grasslands or savannas
Temperate grasslands

The forest biome

A Wisconsin forest. About 420 million years ago, during the Silurian Period, ancient plants and arthropods began to occupy the land. Over the millions of years that followed, these land colonizers developed and adapted to their new habitat. The first forests were dominated by giant horsetails, club mosses, and ferns that stood up to 40 feet tall.

Today, forests occupy approximately one-third of Earth's land area, account for over two-thirds of the leaf area of land plants, and contain about 70% of carbon present in living things. They have been held in reverence in folklore and worshipped in ancient religions. However, forests are becoming major casualties of civilization as human populations have increased over the past several thousand years, bringing deforestation, pollution, and industrial usage problems to this important biome.

There are three major types of forests, classed according to latitude:
Tropical
Temperate
Boreal forests (taiga)

The desert biome

Sand dunes in Death Valley National Monument, California. Deserts cover about one fifth of the Earth's surface and occur where rainfall is less than 50 cm/year. Although most deserts, such as the Sahara of North Africa and the deserts of the southwestern U.S., Mexico, and Australia, occur at low latitudes, another kind of desert, cold deserts, occur in the basin and range area of Utah and Nevada and in parts of western Asia. Most deserts have a considerable amount of specialized vegetation, as well as specialized vertebrate and invertebrate animals. Soils often have abundant nutrients because they need only water to become very productive and have little or no organic matter. Disturbances are common in the form of occasional fires or cold weather, and sudden, infrequent, but intense rains that cause flooding.
There are relatively few large mammals in deserts because most are not capable of storing sufficient water and withstanding the heat. Deserts often provide little shelter from the sun for large animals. The dominant animals of warm deserts are nonmammalian vertebrates, such as reptiles. Mammals are usually small, like the kangaroo mice of North American deserts.
Desert biomes can be classified according to several characteristics.There are four major types of deserts:
Hot and dry
Semiarid
Coastal
Cold

The marine biome

Reef fish and coral off Eniwetok atoll in the central Pacific.
Marine regions cover about three-fourths of the Earth's surface and include oceans, coral reefs, and estuaries. Marine algae supply much of the world's oxygen supply and take in a huge amount of atmospheric carbon dioxide. The evaporation of the seawater provides rainwater for the land.
Oceans
Coral reefs
Estuaries

The freshwater biome

A lake at Acadia National Park, Maine.
Freshwater is defined as having a low salt concentration — usually less than 1%. Plants and animals in freshwater regions are adjusted to the low salt content and would not be able to survive in areas of high salt concentration (i.e., ocean). There are different types of freshwater regions:
Ponds and lakes
Streams and rivers
Wetlands