Biomes are collections of Ecosystems which each have similar conditions and inhabitants.  We'll examine the six most common Land Biomes in this unit of study.  Below is a brief summary of each Biome. 

The Tundra Biome

 Most Tundra though is located in the polar zones, near the North and South poles.  Arctic Tundra is found in Asia, Europe, North America, near the South Pole and near the North Pole.  Alpine Tundra is located in the high mountains of Europe, Asia, North America and South America. Alpine Tundra is generally warmer than the Arctic Tundra.
 Alpine tundra receives more rain.  Lower slopes dominated by plants, higher tundra only supports lichen and moss.  Slope, terrain, moisture, wind will affect plant life.

About 20% of Earth's surface is considered Tundra, most is located near the North Pole.  The Tundra is Earth's chilliest Biome, you can get frostbite in only 30 seconds!  Snow tends to stay in this biome for most of the year.  As a matter of fact, snow is a big part of the daily life for inhabitants of this biome for most of the year!  

The Tundra is strangely dry, receiving only about 10 inches of precipitation each year.  The problem is that it's so cold, that the snow rarely melts!

The Tundra is also unusual in the amount of sunlight it receives.  At times in the summer, the area receives sunlight nearly 24 hours each day!  The sun NEVER sets!  Even in the middle of the night, it's light outside.  It never gets fully dark!  How weird is that?  You can understand why the Tundra is called "Land of the Midnight Sun".   Even worse, in the Winter, it never really gets light!  Yup, it's dark pretty much all day and night long.  Even at noon, the sky is only dimly lit by the weak sunlight that this area receives during the long, cold and dark winter.  It must take some "getting used to"  by the residents of this part of the world, huh?

The soil in the Tundra is considered "Perma Frost", remaining permanently frozen. Thin layer of topsoil, not very rich, and beneath that, 2000 feet of permafrost.  Never thaws, even in summer.  Topsoil thaws in summer, often boggy and wet since permafrost doesn't allow drainage.  This severely limits the plant life in this area, as you can imagine.

During the Winter, the temperatures range from -13º F to +41º F.  Coldest ever?  Northeaster Siberia -93 Fahrenheit! -93!!!!!

Summer in the Tundra is sadly very short, lasting only a short six weeks or so. And you thought we had it bad in Maine!

Obviously, Plant and Animal life is severely limited in the Tundra due to the cold temperatures and harsh conditions. Only 1% of all Earth's animals live here in the Tundra.  Animal adaptations:  Fat, thick fur, some with hollow hair for insulation,  puffy feathers, insulation.  Breed and raise young quickly.  Various other strategies to survive cold.  Many show MIGRATION, always returning for the short arctic summer.  Attraction is BUGS!  Shallow water on Tundra make great place for insects to breed.  Birds arrive for food.  Climate is also good for birds to breed and raise young.

Plants in the Tundra all have many specialized adaptations which allow them to survive in such a harsh climate.  Plants here tend to have shallow roots, and tend to be small, growing low to the ground (to protect them from the winds), taller plants simply wouldn't survive the windy conditions!  Some plants have overlapping leaves as a form of insulation.   Many plants have sap in their stems which acts as a type of antifreeze to protect them from the cold temperatures.  Some plants have hairs on their stems and leaves to trap warmth.  Others are dark colored to better absorb heat to survive the freezing temperatures.  Plants tend to grow in bunches, and some, like lichens and some mosses, are able to grow without soil, often clinging to bare rock surfaces!  Lichens are most common life form in tundra.  A combination of Fungi and algae, the algae makes food for both.  Mosses can thrive without soil.  Grow low to the ground to stay warm.

The Coniferous Forest Biome

This is the largest land biome on Earth!  It is located in the northern most region of the Temperate Climate Zone.  This Biome is cold and snowy for at least part of the year.  The summers are fairly short and plants must survive with only a short growing season.  This means that there are fewer plants in this Biome than you would expect.  Trees such as the Pine, Fir and Spruce have needles, not leaves.  They are cone-bearing trees.  These trees are also called "Evergreens" because they don't lose their needles in the fall.  This is actually a useful adaptation, since no energy needs to be wasted regrowing lost leaves in the Spring (like in the Deciduous Forest a little further South).  The Evergreen trees also don't lose their needles all at once, but rather sort of lose a few all year long.  The needles are replaced as they're lost throughout the year, rather than  all at once.  This is also an adaptations which helps trees conserve their limited energy.  These trees tend to have darker colors, to help them better absorb the sun's rays and gather warmth.  The trees themselves have a triangular shape, which is helpful in letting ice and snow drop off, rather than weighing down, and possibly breaking the branches and limbs.  Even the sap, or resin, in the needles and the tree itself is a useful adaptation.  The  sap can be poisonous to things  like insects or animals so that these creatures don't damage the tree by eating it, or burrowing into it!  The soil is acidic, in part due to the many needles deposited there and slowly decomposing.  This acidic soil is difficult to live in, and there are plants with interesting adaptations, such as the pitcher plant, which is native to the coniferous forest.

Precip:  50inches per year.


HUMAN IMPACT ON THE CONIFEROUS FOREST:  Wood used for fuel, trees, paper and other products.  In past 200 years, with Industrial Revolution, 30% cut worldwide.  Northernmost coniferous forests were somewhat spared due to their inaccessible location and harsh conditions, even they are being cut today.  Since the average lifespan of a conifer is 200 years, it takes that long for a new tree to replace it.  "Old Growth" forests take 200 years to grow back. .They're generally older  mature forests, generally undisturbed by human activities.  When logged we lose not only the plants, but also the animals that live there as well.   RECYCLE...the trees you save come from the coniferous forests.

The Deciduous Forest Biome

This Biome's name comes from the Latin words for "fall off".  That's because the trees common in this Biome lose their leaves in the fall, and regrow them in the Spring!  This Biome is found in the Northeastern part of North America, Western and Central Europe and Northwest Asia.  Here in this part of the Temperate Climate Zone, the Deciduous Forests receive from 80 to 200 cm of precipitation each year.  Temperatures are, well, temperate, averaging 86º F in Summer and 10ºF in Winter.  Not too shabby!  The soil in this part of the world is extremely fertile and deep  because of the large quantities of decomposing leaf material.  The soil in these forests consists of a deeper layer of Humus (spongy, decomposing plant and animal matter) with a top layer of "Leaf Litter" composed of dead and decaying leaves.

An interesting adaptation of the trees in this forest is that they lose their leaves in the Fall each year.  The leaves change color as the chlorophyll breaks down, allowing the other more vibrant colors to shine through!  For a time, the forest is awash with the firery colors of fall!  Reds, Oranges and Yellows of every shade add to this blaze of color.  The  leaves eventually fall to the ground and add to the nutrient rich soil of this biome.  The trees then become dormant to allow themselves to conserve energy and survive winter.  As an added bonus, the bare, leafless branches of the trees don't provide much of a base for ice and snow to accumulate.  This ends up preventing a lot of broken limbs that would need repair and regrowth in the Spring.

Deciduous Forests typically have two layers:  the tallest trees making up the Emergent Layer.  this is 80-100 feet tall, and the trees here may live 100 to 250 years!  This Emergent layer is also called the Canopy.  Beneath the Canopy is the Understory, consisting of shorter trees, shrubs and bushes along with the plants of the forest floor.

Animals in this Biome also show many interesting adaptations.  For example, nearly 70% of the birds that live in these forests migrate to warmer climates during the cold winter months.  Smart birds.  

The Tropical Rainforest Biome

 This Biome once covered about 50% of the Earth's surface.  Today, only about 7% of Earth's surface is covered by the tropical broadleaf rain forest biome.  There are literally millions of different species in these forests however, accounting for nearly 80% of ALL species on Earth!  This Biome boasts the largest Biodiversity of any biome on Earth.  Some estimates that there may be 20 million different species, mostly unknown and undiscovered, living in these forests.  The Tropical Rainforest is also the oldest Biome on Earth.  

Temperatures in this Biome average from 75º F to 86º F all year long!  It is also the wettest Biome on Earth, averaging up to 80 inches of precipitation each year!  The forest slowly recycles all of this water, thanks to the Hydrologic Cycle and massive amounts of transpiration from the foliage of this biome.

The Tropical Rainforest is divided into four distinct layers:
    The Emergent Layer- the upper most parts of the trees.   These tops of trees are like the tops of an open umbrella.
    The Canopy- This is the most crowded layer, and about 90% of all the organisms in the rainforest live in this part of it.  There's lots of available sunlight in this region,     and that means     that there's lots and lots of photosynthesis going on!
    The Understory-  This is the part that lies just beneath the canopy.  The amount of available light is dramatically lower than in the sunlit Canopy just above.
    The Forest Floor-  many decomposers, such as Fungi, Bacteria and animals such as slugs and snails live on the forest floor.  Only about 1% of the sunlight that found     at the Canopy           level ever reaches the forest floor.

Adaptations in this biome are plentiful!  The tiny hummingbird's bill is used to get nectar     from deep within flowers.  Not only is the shape of the beak of the hummingbird     an example  of an adaptation, but the shape of the flowers is as well!  The plants actually benefit from the hummingbird's attentions, because as     the hummingbird moves from blossom to blossom, a bit of the flower's pollen clings to the hummingbird, and is thereby distributed throughout this ecosystem.

Snakes, frogs, birds, and insects all show evidence of camouflage, a valuable adaptation which allows each to blend into the background and evade detection.  

We're all familiar with the Parrot, but did you know that it's a colorful example of many     different useful adaptations?  The Parrot's short wings allow it great     maneuverability through the dense forest, its strong claws allow it to grab onto branches, its strong beak allows it to crack the seeds     and nuts it eats for food, and its loud voice echoes through the canopy to allow it to easily communicate with others of its species.

The Desert Biome

 About one fifth of Earth's land surface is covered with desert.  Does that surprise you?  With its low rainfall and extreme temperatures, and strong winds.  the desert is also a difficult Biome in which to live.  The environment is characterized by hot days and cold nights.  Deserts by definition receive little rainfall, averaging less than 10 inches each year!  

Many form near mountains. (rising air loses moisture as it cools(windward side), ocean side moist, or snowy, other side dry desert environments.(leeward side)

This arid environment has no clouds or fog to block the sunlight during the day, or to help hold heat near the surface at night.  The soil is very poor, containing few nutrients. . Not much water means decay is slow, so the soil ends up with fewer nutrients to feed plants.  Desert Biomes are found in both the tropical and temperate climate zones.  Some  scientists consider the polar zones to be cold deserts, because they receive so little precipitation.  WAIT A MINUTE!  Doesn't it snow all the time in polar areas?  Discuss.

Deserts aren't all the same.  Some are hot, some are cool, or cold.  

Despite these difficult conditions, an amazing variety of organisms manage to call the desert biome their home

Not much grass, few trees.  This contributes to the windy conditions present in deserts.  

Adaptations often seen in animals are a Nocturnal Lifestyle, in which they sleep during the hottest parts of the day, and are more active at night when conditions are milder.  Reptiles are cold blooded, and have dry scaly skin which helps them to to retain water.  Many animals of the desert are venomous, and adaptation which allows their bite to kill their prey quickly, thus conserving energy. Rattlesnakes adaptation to warn off intruders in an environment where there's not many places to hide.  

Generally not many larger animals.  Little food, little shelter.  Smaller animals are much more common.  

Animal adaptations to conserve water:  Skin, Burrowing, nocturnal

Plants have waxy leaves to prevent water loss.  The root systems may also run quite deep, in search of available water.  Many plants and animals have developed ways to store water within their cells, as a way of surviving in the naturally arid environment.

Human Impacts:  

Overuse of land.  Topsoil lost.  Land turns to desert.  Called Desertification.  Can also be caused by overgrazing, destroying both plants and roots.  

The Grasslands Biome

This biome is also called the Prairie, the Pampas, the Steppes, the Savanna and the Veldt, depending on where in the the world you go to sleep at night.

The Grasslands Biome has lots and lots of plants, just very few trees.  Grasslands cover about 12% of the globe.  Once, the percentage was much higher, but today, most grasslands have been cleared to use for the growing of crops.  Most grasslands are in the Temperate Climate Zone, which is located between the poles and the equator.  Winters tend to be cold and damp with temperatures dropping as low as -40º F.  The summers tend to be warm and dry, with temperatures often reaching 100º F during the day.  

The landscape is mostly flat, and strong winds are usually present.  Since there are few trees to block the sun, the amount of sunlight available to the plants of this biome is unusually high.

The many species of grasses in this biome often show creative adaptations to help them to survive and thrive in this environment.  For one thing, the grasses tend to have extensive root systems.  These systems of roots allow them to gather water from the soil and also serve to anchor the plants in the ground so that they are better able to resist the strong winds often seen here.  Many plants have found creative ways to be sure their seeds are spread over as wide of an area as possible.  As a result, many seeds float upon the wind, or cling to the coats of passing animals.  Grasses can often have very deep root systems to help them gather all available moisture.  This trait is especially important since grasslands only receive between 10 and 40 inches of precipitation each year.