BIOMES

mBIOMES

A biome is a large geographical area of distinctive plant and animal groups, which are adapted to that particular environment. The climate and geography of a region determines what type of biome can exist in that region. Major biomes include deserts, forests, grasslands, tundra, and several types of aquatic environments. Biomes are defined as "the world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment". The importance of biomes cannot be overestimated. Biomes have changed and moved many times during the history of life on Earth. More recently, human activities have drastically altered these communities.

MARINE BIOMES
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.

• Oceans
  
• Coral Reef
  
• Estuaries

Coral reefs
Coral reefs are widely distributed in warm shallow waters. They can be found as barriers along continents, fringing islands, and atolls. Naturally, the dominant organisms in coral reefs are corals. Corals are interesting since they consist of both algae (zooanthellae) and tissues of animal polyp. Since reef waters tend to be nutritionally poor, corals obtain nutrients through the algae via photosynthesis and also by extending tentacles to obtain plankton from the water. Besides corals, the fauna include several species of microorganisms, invertebrates, fishes, sea urchins, octopuses, and sea stars.

FOREST BIOMES
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.

• Tropical
  
• Temperated
  
• Boreal Forest (taiga)
  

Boreal Forest (taiga)
Boreal forests, or taiga, represent the largest terrestial biome. Occuring between 50 and 60 degrees north latitudes, boreal forests can be found in the broad belt of Eurasia and North America: two-thirds in Siberia with the rest in Scandinavia, Alaska, and Canada. Seasons are divided into short, moist, and moderately warm summers and long, cold, and dry winters. The length of the growing season in boreal forests is 130 days.

• Temperatures are very low.
  
• Precipitation is primarily in the form of snow, 40-100 cm annually.
  
• Soil is thin, nutrient-poor, and acidic.
  
• Canopy permits low light penetration, and as a result, understory is limited.
  
• Flora consist mostly of cold-tolerant evergreen conifers with needle-like leaves, such as pine, fir, and spruce.
  
• Fauna include woodpeckers, hawks, moose, bear, weasel, lynx, fox, wolf, deer, hares, chipmunks, shrews, and bats.
  

DESSERT BIOMES
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.

• Hot and dry
  
• Semiarid
  
• Coastal
  
• Cold
  

Hot and Dry
The four major North American deserts of this type are the Chihuahuan, Sonoran, Mojave and Great Basin. Others outside the U.S. include the Southern Asian realm, Neotropical (South and Central America), Ethiopian (Africa) and Australian.
The seasons are generally warm throughout the year and very hot in the summer. The winters usually bring little rainfall.
Temperatures exhibit daily extremes because the atmosphere contains little humidity to block the Sun's rays. Desert surfaces receive a little more than twice the solar radiation received by humid regions and lose almost twice as much heat at night.
The animals include small nocturnal (active at night) carnivores. The dominant animals are burrowers and kangaroo rats. There are also insects, arachnids, reptiles and birds. The animals stay inactive in protected hideaways during the hot day and come out to forage at dusk, dawn or at night, when the desert is cooler.


BIBLIOGRAPHY: http://www.ucmp.berkeley.edu/exhibits/biomes/deserts.php
http://studentsacrossborders.arizona.edu/images/sag_1.jpg

How are Biomes related to human action and ecological impact?

First I should difine you what could be the "human actions". Human actions are the industrial things that man has created during these years, which has a direct effect on the planet. We could not say things have stay the same 100 years back. The temperature has increase to a worring point. The chemical gases industries spill out are producing the global warming. The global warming starts by melting up al the glaciers and ice on the poles and here set off all the ecological problems. The hurricanes, the floods, the constant changing of temperature affects negatively the Earth. We should take as matter of importance and start working on stop the global warming.

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