Major Biomes of the Blue planet

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 Earth has many different environments, varying in temperature, moisture, light, and many other factors. Each of these habitats has distinct life forms living in it, forming complex communities of interdependent organisms. A complex community of plants and animals in a region and a climate is called a biome.

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.

Did you know there are two types of Rainforest -- the temperate and the tropical? Tropical rainforests are found close to the equator. Temperate rainforests are found along coasts in the temperate zone, such as the Pacific Northwest of the USA. Both are endangered!

There are two types of rainforests -- tropical and temperate. Tropical and temperate rainforests share certain characteristics. For example, most trees flare at the base. Vegetation is dense, tall and very green. Both types of rainforests are rich in plant and animal species, although the diversity is greater in the tropical rainforest.

Montane forests are found in mountainous areas and may contain plants such as oaks, rhododendrons, and pines, which are characteristic of temperate deciduous forests. At higher altitudes, temperatures are cooler. Even close to the equator, frost and snow can occur.

Precipitation and Climate
Both tropical and temperate rainforests are very lush and wet. The tropical rainforest has downpours at the rate of two inches an hour adding up to some 400 inches of rain per year. It rains a lot in the temperate rainforest, too -- about 100 inches per year. And even more moisture comes from the coastal fog that hovers among the trees.

Are all Tropical Forests, Rainforests?
Only a small percentage of the tropical forests are rainforests. To be a tropical rainforest, forested areas must:

Consequently, many forested areas in the tropics are not rainforests. Forests that receive irregular rainfall (monsoons followed by a dry season) are moist deciduous forests. Trees in these forests may drop their leaves in the dry season.

How cold is cold? The tundra biome is at the top of the world -- around the North Pole! Below a thin layer of tundra soil is its permafrost, a permanently frozen layer of ground. During the brief summers, the top section of the soil may thaw just long enough to allow plants and microorganisms to grow and reproduce.

The tundra is located at the top of the world, near the North Pole. This enormous biome, extremely uniform in appearance, covers a fifth of the earth's surface.

The most distinctive characteristic of tundra soil is its permafrost, a permanently frozen layer of ground. During the brief summers, the top section of the soil may thaw out allowing plants and microorganisms to grow and reproduce. However, these plants and microorganisms become dormant during the cold winter months.

There is another region called alpine tundra, which is found on the tops of tall, cold mountains.

The arctic tundra is at the top of the world -- around the North Pole.
Animals are adapted to handle cold winters and to breed and raise young quickly in the very short and cool summers.

Temperatures during the arctic winter can dip to -60 F (-51 C)! The average temperature of the warmest month is between 50 F (10 C) and 32 F (0 C). Sometimes as few as 55 days per year have a mean temperature higher than 32 F (0 C). The average annual temperature is only 10 to 20F (-12C to -6C).

The soil is often frozen. Permafrost, or permanent ice, usually exists within a meter of the surface. Water is unavailable during most of the year.

Annual precipitation is very low, usually less than 10 inches (25 centimeters).

The Taiga biome stretches across a large portion of Canada, Europe and Asia. It is the largest biome in the world. Winters are cold. Summers are warm. Lots of conifers grow here.

The taiga is the largest biome. The taiga is primarily a coniferous forest (evergreen trees with needles) like the temperate rainforest, but the taiga is located between 50 degrees latitude north and the Arctic circle. Many coniferous trees (evergreens with needles) grow in the taiga. The taiga has fewer animal species than the tropical or temperate deciduous forests.

The taiga is very, very cold in the winter. But when the warm summer comes, the ice and snow melt. The sun shines for days in the summer, because the taiga is near the top of the world. Insects breed in the melting water. Birds come to the taiga to nest and lay their eggs in the spring and to eat the plentiful insects.

Taiga Facts

In the taiga, the average temperature is below freezing for six months of the year. Total yearly precipitation in the taiga is 12 - 33 inches (30 - 85 centimeters). Although the cold winters have some snowfall, most of the precipitation comes during the warm, humid summer months.

Because of the tilt of the earth on its axis, in the taiga you'll find long nights in the winter and long days in the summer.

During the summer months, the taiga fills up with millions of insects. Birds, who eat insects, migrate every year for the plentiful food supply.

The taiga is prone to wildfires. Many trees have adapted to this by growing thick bark, which can protect a tree from a mild fire.

Decomposition
Because of cool temperatures decomposition is slow in the taiga. Undecayed vegetation builds up on the forest floor, making it feel like a sponge. Since decomposition is slow, the soil is thin and lacking in nutrients. Trees grow taller where warmer temperatures allow for faster decomposition or by streams and rivers that carry nutrients from higher ground.

The desert is a land of extremes: extreme heat and extreme dryness; sudden flash floods and cold nights. Because deserts are such a harsh environment, deserts often have names likes "Death Valley," "the empty quarter," and "the place from where there is no return."

Dryness
Deserts are usually very, very dry. Even the wettest deserts get less than ten inches of precipitation a year.

In most places, rain falls steadily throughout the year. But in the desert, there may be only a few periods of rains per year with a lot of time between rains. When it does rain, there may be quite a downpour! After the rain, desert flowers bloom.

Hot During the Day, Cool at Night
Everyone knows that during the day many deserts are hot, very hot. Temperatures in excess of 100 degrees fahrenheit are not uncommon. Yet at night, the same deserts can have temperatures fall into the 40s or 50s? Why?

Other biomes are insulated by their humidity (water vapor in the air). Temperate deciduous forests, for example, may have 80 percent humidity or more during the day. This water reflects and absorbs sunlight and the energy it brings. At night the water acts like a blanket, trapping heat inside the forest.

Since deserts usually have only between 10 and 20 percent humidity to trap temperatures and have so few trees and other vegetation to retain heat, they cool down rapidly when the sun sets, and heat up quickly after the sun rises.

Many deserts are found in bands along 30 degrees latitude north and 30 degrees latitude south.

Some deserts located by mountains and are caused by the "rainshadow" effect. As air moves up over a mountain range, it gets cold and loses the ability to hold moisture -- so it rains or snows. When the air moves down the other side of the mountain, it gets warmer. Warm air can hold lots of moisture, so it doesn't rain as much, and a desert is formed.

The main form of precipitation in a hot desert is rain. But that's only ten inches or less of rain per year. Hot Deserts of the World
Name *Location*	Size	Physical Features	Some Plants & Animals	Special Facts
Arabian Arabian Peninsula	900,000 mi² 2,300,000 km²	Covered almost entirely by sand; has some of the most extensive stretches of sand dunes in the world.	acacia, oleander, saltbush desert locust, dromedary camel, gazelle, lizard, jackal, oryx	Nomadic Bedouin tribes have travelled through the Arabian Desert for thousands of years.
Australian (Great Sandy, Victoria, Simpson, Gibson, and Sturt) Australia	890,00 mi² 2,300,000 km² (1/3 of Australia)	Great Sandy, Victoria, and Simpson are sandy; Gibson and Sturt are stony.	acacia, casuarina tree, eucalyptus, saltbush, spinifex grass blue-tongued lizard, dingo, fat-tailed mouse, kangaroo, marsupial mole, rabbit-eared bandicoot, sand goanna, spinifex hopping mouse, throny devil	Aborigines have lived in the Australian deserts for over 30,000 years.
Chihuahuan North Central Mexico and Southwestern United States (Arizona, New Mexico, Texas)	175,000 mi² 455,000 km²	High plateau covered by stony areas and sandy soil. Many mountains and mesas.	cacti, chihuahuan flax, creosote bush, lechuguilla, mesquite, mexican gold poppy coyote, diamondback rattlesnake, javelina, kangaroo rat, roadrunner	Largest North American desert. Big Bend National Park located here; more species of birds seen in Big Bend than in any other National Park in the U.S.
Kalahari Southwestern Africa	200,000 mi² 520,000 km²	Covered by sand dunes and gravel plains.	acacia, aloe gazelle, gerbil, ground squirrel, hyena, jackel, sandgrouse, springbok	Bushman have lived in the Kalahari for 20,000 years.
Mojave Southwestern United States (Arizona, California, Nevada)	25,000 mi² 65,000 km²	Covered by sandy soil, gravelly pavement, and salt flats.	creosote bush, desert sand verbena, joshua tree, mesquite bighorn sheep, chuckwalla, coyote, jackrabbit, sidewinder, zebra-tailed lizard	Death Valley located in this desert.
Monte Argentina	125,000 mi² 325,000 km²	Covered by sand and soil	cardon cactus, creosote bush, paloverde armadillo, cavy, jaguarundi, puma, tinamou, tuco-tuco	Very similar to the Sonoran Desert
Sahara Northern Africa	3,500,000 mi² 9,100,000 km²	Covered by mountains, rocky areas, gravel plains, salt flats, huge areas of dunes. Areas in the central sometimes get no rain for years at a time.	acacia, grasses, tamarisks addax antelope, dorcas gazelle, fennec fox, horned viper, jackal, jerboa, sandgrouse, spiny-yailed lizard	Largest desert in the world. Fewer than 2 million inhabitants (mostly nomads such as the Tuareg). Crossed by Arab caravans since the 10th century.
Sonoran Southwestern United States (Arizona, California) and parts of Mexico (Baja Peninsula, Sonora)	120,000 mi² 312,000 km²	Covered by sand, soil, and gravelly pavement. Gets more rain than any other North American desert.	agave, coulter's globemallow, creosote bush, desert mariposa lily, mesquite, ocotillo, paloverde, saguaro coati, elf owl, gila monster, kangaroo rat, pack rat, roadrunner, sidewinder, tarantula	Most complex animal-plant community of any desert. One of the most beautiful deserts in the world.
Thar India and Pakistan	77,000 mi² 200,000 km²	Majority of desert covered by sand dunes; rest covered by gravel plains	acacia, euphorbias, grasses, shrubs black buck, dromedary camel, great Indian bustard, Indian spiny-tailed lizard, jackel, sandgrouse	Small villages of ten to twenty houses scattered throughout the Thar.

The main form of precipitation in a cold desert is snow -- but only ten inches or less per year. Cold Deserts of the World
Name *Location*	Size	Physical Features	Some Plants & Animals	Special Facts
Atacama Coasts of Peru and Chile	54,000 mi² 140,000 km²	Covered by sand dunes and pebbles. One of the driest areas on earth.	bunchgrass, cardon cactus, tamaruga trees lizards, llama, Peruvian fox, nesting area for many seabirds	Only a few thousand people (mostly farmers) live in the inland desert areas. Large deposits of sodium nitrate are found in the desert. Sodium nitrate is used to make gunpowder.
Gobi Northern China and Southern Mongolia	450,000 mi² 1,200,000 km²	Covered by sandy soil and areas of small stones called "gobi."	camel's thorn, grasses bactrian bamel, gazelle, gerbil, jerboa, lizards, onager, wolf	Crossed by Genghis Khan in the early 13th century. Many nomads now settling on government-run farms.
Great Basin Western United States (Idaho, Nevada, Oregon, and Utah)	158,000 mi² 411,000 km²	Covered by sand, gravel, and clay. Many moutains ranges, basins, and large expanses of salt flats.	greasewood, sagebrush, shadscale bighorn sheep, jackrabbit, pocket mouse, poor-will, pronghorn antelope, sage thrasher, side-blotched lizard	Great Salt Lake located here.
Iranian Iran, Afghanistan, and Pakistan	150,000 mi² 390,000 km²	Covered by coarse gray soil, stony pavement, and salt flats.	grasses, pistachio trees, shrubs monitor lizard, onager, oryx, scorpion	World's largest salt flat located here.
Namib Coasts of Southwestern Africa	52,000 mi² 135,000 km²	Covered by sand dunes along the coast and gravel farther inland.	aloe, bunchgrass, lichens, welwitschia darkling beetle, fringe-toed lizard, golden mole, jackal, sidewinder, viper, web-footed gecko	Coast of the Namib Desert is world's greatest source of gemstones.
Takla Makan Western China	600,000 mi² 1,600,000 km²	Covered by sand dunes and rocky soil.	grasses, shrubs bactrian camel, jerboa, long-eared hedgehog, gazelle	The word "Takla Makan" means "place from which there is no return." Crossed by Marco Polo in the 13th Century.
Turkestan Parts of the Middle East and Southwestern Russia	215,000 mi² 559,000 km²	Covered mostly by extensive stretches of sand dunes.	alhagi shrub, saxaul tree, sedges, thick ground cover desert tortoise, gazelle, gerbil, saiga antelope	Crossed by caravans following silk route from China in Europe in ancient times. The great city of Samarkand, once a cultural and religious center of central Asia, was located here.

World's Largest Deserts
Desert	Location	Square Miles	Square Kilometers
Sahara	North Africa	3,500,000	9,065,000
Gobi	Mongolia-China	500,000	1,295,000
Kalahari	Southern Africa	225,000	582,000
Great Victoria	Australia	150,000	338,500
Great Sandy	Australia	150,000	338,500

Deserts of North America
Name *Location*	Size	Physical Features	Some Plants & Animals	Special Facts
Chihuahuan North Central Mexico and Southwestern United States (Arizona, New Mexico, Texas)	175,000 mi² 455,000 km²	High plateau covered by stony areas and sandy soil. Many mountains and mesas.	cacti, chihuahuan flax, creosote bush, lechuguilla, mesquite, mexican gold poppy coyote, diamondback rattlesnake, javelina, kangaroo rat, roadrunner	Largest North American desert. Big Bend National Park located here; more species of birds seen in Big Bend than in any other National Park in the U.S.
Great Basin Western United States (Idaho, Nevada, Oregon, and Utah)	158,000 mi² 411,000 km²	Covered by sand, gravel, and clay. Many moutains ranges, basins, and large expanses of salt flats.	greasewood, sagebrush, shadscale bighorn sheep, jackrabbit, pocket mouse, poor-will, pronghorn antelope, sage thrasher, side-blotched lizard	Great Salt Lake located here.
Mojave Southwestern United States (Arizona, California, Nevada)	25,000 mi² 65,000 km²	Covered by sandy soil, gravelly pavement, and salt flats.	creosote bush, desert sand verbena, joshua tree, mesquite bighorn sheep, chuckwalla, coyote, jackrabbit, sidewinder, zebra-tailed lizard	Death Valley located in this desert.
Sonoran Southwestern United States (Arizona, California) and parts of Mexico (Baja Peninsula, Sonora)	120,000 mi² 312,000 km²	Covered by sand, soil, and gravelly pavement. Gets more rain than any other North American desert.	agave, coulter's globemallow, creosote bush, desert mariposa lily, mesquite, ocotillo, paloverde, saguaro coati, elf owl, gila monster, kangaroo rat, pack rat, roadrunner, sidewinder, tarantula	Most complex animal-plant community of any desert.

The Temperate Deciduous Forest biome has four seasons of winter, spring, summer, and fall. Animals and plants have special adaptations to cope with these yearly changes.

One of the most interesting features of the temperate deciduous forest is its changing seasons.

The word "deciduous" means exactly what the leaves on these trees do: change color in autumn, fall off in the winter, and grow back again in the spring. This adaptation helps trees in the forest survive winter.

The temperate deciduous gets the second-most amount of rainfall per year. In the winter, precipitation (rainfall) is in the form of sleet, snow, and hail. The average rainfall is 30 to 60 inches per year. The average temperature of the forest is about 50 degrees Fahrenheit.

How do deciduous trees and plants survive the changing seasons?
Like all living things, deciduous trees and plants have special adaptations to stay alive.

Summer is a busy time for deciduous trees. Their broad leaves capture energy from the sun and convert it to food by photosynthesis. Some of the food is used for growth and some is stored in the roots for next spring.

During the shorter days and cooler weather of autumn, green chlorophyll in the leaves begins to decompose, revealing brilliant oranges, yellows, and reds. Actually, these colors were present in the leaves all year long, but had been hidden by the green pigment of the chlorophyll.

To prepare for winter, deciduous trees and plants become dormant. They loose their leaves and seal the places where leaves were attached with a protective covering called a leaf scar. If they kept their leaves, the water in the leaves would freeze into ice, damaging the leaves and leaving the plant vulnerable to bacteria or fungi. Plants also make a concentrated sugar solution to stop water from freezing in their stems.

The longer days and warmer weather of spring signal to the trees to grow new leaves and begin photosynthesis again.

The deciduous forests are located primarily in the eastern half of the United States, Canada, Europe, parts of Russia, China, and Japan.

The temperate deciduous forest has four changing seasons. These forests have hot summers and cold winters. As the seasons change, so do the colors of the leaves of the deciduous trees. Deciduous means that these plants lose their leaves every year and grow them back.

Reasons for Seasons
The four seasons happen because of the tilt of the Earth's axis. At different times of the year, the sun's rays hit different parts of the globe more directly. The angle of the Earth's axis tilts the Northern Hemisphere towards the sun during the summer.

Without the tilt of the earth's axis, we wouldn't have seasons. Instead, the areas around the equator would receive the most sun and the northern and southern hemispheres would be stuck in a gradual gradient of hot to cold. The seasons would not change, it would be about the same temperature year round and there would be no seasons.

Is it true that the earth is closer to the sun in winter?
Because of its elliptical orbit, the earth is closer to the sun during the northern hemisphere's winter. However, distance from the sun does not affect the seasons. The tilt of the earth's axis causes the seasons to change.

Grasslands are big open spaces. There are not many bushes in the grassland. Trees are found only by rivers and streams. The grassland seems like an endless ocean of grass.

Grasslands receive about 10 to 30 inches of rain per year. If they received more rain, the grasslands would become a forest. If they received less, they would become a desert. Grasslands are often located between deserts and forests.

Grassland soil tends to be deep and fertile. The roots of perennial grasses usually penetrate far into the soil. In North America, the prairies were once inhabited by huge herds of bison and pronghorns who fed on the prairie grasses. These herds are almost gone now, and most of the prairies have been converted into the richest agricultural region on earth. Crops grow well in the rich soil.

In the United States and Canada there are three types of grasslands (or prairies):

Grasslands are found on either side of two desert belts that circle the earth. About one quarter of the earth's land is in the grasslands.

Temperate grasslands once covered much of the interior of North America, and they were common in Eurasia and South America as well. They are highly productive when they are first converted to agricultural uses because the organic material in the soil comes from hundreds of thousands of years of decomposition.

In North America, the prairies were once inhabited by huge herds of bison and pronghorns, which were hunted by wolves, bears, and other predators. Where U.S. prairies have been converted to farmland, the large herds and predators that followed them are gone now.

In addition to the prairies of the U.S. Midwest, the world has other grasslands that go by different names. In South America, grasslands are called "pampas"; in Europe, "steppes"; in Africa, "savannas".

Water makes up the largest part of the biosphere, covering nearly 75% of the Earth’s surface. Aquatic regions house numerous species of plants and animals, both large and small.

The aquatic biome can be broken down into two basic regions: freshwater (i.e, ponds and rivers) and marine (i.e, oceans and estuaries).

Freshwater Regions
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, and wetlands.

Marine Regions
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.

	Tropical	Temperate
Temperatures	warm	cool
Number of tree species	many (hundreds)	few (10-20)
Types of leaves	broadleaf	needles
Age of trees	50-100 years	500-1000 years
Epiphytes	lots of different kinds including orchids and bromeliads	mostly mosses and ferns
Decomposition rate	rapid	slow

Taiga Temperatures
	Low	High
Winter	-65 F (-54 C)	30 F (-1 C)
Summer	20 F (-7 C)	70 F (21 C)

Tall Grass Prairie	The Tall Grass Prairie lies mainly in the eastern portion of the Midwest. The grasses here often grow to be five feet tall. The annual rain totals here approach 30 inches.
Mixed Grass Prairie	The Mixed Grass Prairie lies mainly in the middle portion of the Midwest. The grasses here often grow to be two and three feet tall. Typically, there are 15 to 25 inches of rain per year. This is the prairie where the buffalo once roamed.
Short Grass Prairie	The Short Grass Prairie lies mainly in the western portion of the Midwest, hugging the coast of the deserts and the Rocky Mountains into Canada. The grasses here grow to be no more than two feet tall. There is usually little more than ten inches of rain per year in these short grass prairies. Prairie Dogs are common in this area.

Major Biomes of the Blue planet

World's Largest Deserts

Deserts of North America