Transcript Biomes are the major types of terrestrial ecosystems

Biomes are the major
types of terrestrial
ecosystems
34.3
What is a Biome???
The major types of terrestrial
ecosystems that cover large regions
of Earth are called biomes.
 Each biome is characterized by
communities of plants and other
organisms that are adapted to its
climate and other abiotic factors.
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Biomes
But while the landscapes may appear
similar across a biome, the specific
organisms vary in different parts of the
world.
 For example, bison and pronghorns
graze in North American grasslands,
while the grazing mammals in Asian
grasslands include saiga (also called
"antelope goats") and yaks.
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Biomes
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Figure 34-9 shows the
natural distribution of
eight major biomes,
plus large areas of ice
found near both poles.
Notice that there are
some latitudinal
patterns—certain
biomes appear at
similar latitudes on
several different
continents.
Tropical Forest
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Tropical forests occur near the equator
where temperatures are warm year-round.
One major type of tropical forest, the
tropical rain forest, can receive as much as
350 centimeters of rainfall yearly.
These ideal growing conditions result in a
lush diversity of plants growing in vertical
layers.
Tropical Forests
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Of all biomes, tropical rain forests have the
greatest diversity of life, with an estimated
50 percent of all known species on Earth.
Rain forests on the island of Madagascar,
off the coast of Africa, are home to some
8,000 species of flowering plants, 80
percent of which occur only there.
Many of the unique species provide food,
medicine, and other valuable products.
Tropical Forests
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Rain forests in
Madagascar and
many other parts of
the world are
shrinking.
Clearing forests for
mining, lumber, and
farmland has
affected many
rainforest species.
Tropical Rainforests of the world
Savannas
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Found in tropical regions
of Africa, Australia, and
South America,
savannas are grasslands
with scattered trees.
Savanna grasses grow
rapidly, providing food
for many grazing
animals, such as zebras,
wildebeest, antelope,
and, in Australia,
kangaroos, as well as
numerous insects.
Savannas
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Savannas typically have a warm climate
with alternating wet and dry seasons.
The dry seasons may include long periods
of drought, when no rain falls.
Organisms in the savanna must be able to
cope with drought.
For example, some animals wander until
they find greener pastures or scattered
watering holes.
Deserts

Land areas
receiving less than
30 centimeters of
rain per year are
typically classified
as deserts.
Deserts
Some deserts have surface soil
temperatures above 60°C during the
day and then cool off at night.
 Other deserts, such as those in
central Asia, are relatively cold,
especially during winter nights.
 The driest deserts, such as those in
central Australia and Africa, have little
or no plant life.
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Chaparral
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The chaparral
(shap uh RAL) is a
temperate coastal
biome dominated
by dense
evergreen shrubs.
The climate
consists of mild,
rainy winters and
hot, dry summers.
Chaparral
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The chaparral's dry, woody shrubs are
frequently ignited by lightning and are
adapted to survive periodic brushfires.
In fact, some of the plant species produce
seeds that will germinate only after a hot
fire.
Animals of the chaparral include deer, birds,
and rodents that feed on the shrubs and
their seeds, as well as lizards and snakes.
Temperate Grassland
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The temperate
grassland biome is
characterized by
deep, nutrient-rich
soil that supports a
variety of grass
species and other
plants.
The winters are
colder than in the
tropical savannas
Temperate Grasslands
Grassland soils contain a great
diversity of microorganisms and
animals, including worms, arthropods,
and burrowing rodents.
 Above ground, the North American
grasslands (also known as prairies)
include grazing mammals such as
bison and pronghorns, as well as
coyotes, snakes, lizards, and insects.
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Temperate Deciduous
Forests
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Dense stands of
deciduous trees—trees
that drop their leaves
each year—
characterize temperate
deciduous forests.
These forests occur
throughout the
temperate zone where
there is enough
precipitation to support
the growth of large
trees.
Temperate Deciduous
Forests
In this region winters tend to be very
cold, while summers can be quite hot.
 Common deciduous trees such as
maples, oaks, beeches, and hickory
shed their leaves in autumn, which
helps reduce evaporation during the
winter when water is not easily
replaced from frozen soil.
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Temperate Deciduous
Forests
Mammals found in the temperate
deciduous forests of eastern North
America include deer, squirrels,
chipmunks, foxes, and bears.
 During the cold winter, many of these
animals conserve energy by greatly
reducing their activity levels.
 Some bird species migrate to warmer
climates.
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Coniferous Forest
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Towering conebearing evergreen
trees such as pine,
spruce, fir, and
hemlock characterize
the coniferous forest.
The northern regions
of the biome, also
called the taiga, have
long, cold winters
with heavy snowfall.
Coniferous Forests
In coastal Oregon, Washington, and
British Columbia, Canada, conditions
are warmer and wetter than in most
other coniferous forest areas.
 These forests are actually considered
temperate rain forests because of the
amount of precipitation they receive.
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Tundra
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Bitterly cold
temperatures and high
winds characterize the
tundra.
Tundra communities are
found within the Arctic
Circle and on high
mountaintops at all
latitudes due to the
similar conditions there
(Figure 34-17).
The permanently frozen
subsoil, called
permafrost, ranges in
depth from a few meters
to 1,500 meters.
Tundra
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During the brief Arctic growing season,
clouds of mosquitoes fill the air. Lemmings,
caribou, and reindeer eat the tundra ground
cover.
Some tundra animals, including the arctic
hare and snowy owl, turn white in the
winter, allowing them to blend in with the
snow.
During the summer they turn brown, better
enabling them to hide in their rock-strewn
environment.