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
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,
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
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.
REPRESENTATIVE INHABITANTS: CONIFERS, OWL, MOOSE, BEAR,
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
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.
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.
- 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!
- 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-
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
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
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,
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
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
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.