Transcript Major Ecosystems of the Biosphere

Major Ecosystems of the
Biosphere
Chapter 39
Climate Characterization
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Climate
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Average yearly temperature and precipitation of a region
When terrestrial ecosystems are plotted according
to their climate, a particular distribution pattern
results
Terrestrial Ecosystems
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Tundra
Tiaga (corniferous forests)
Temperate deciduous forest
Grasslands (& savannahs)
Desert
Tropical rainforest
1. Tundra
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Encircles the Earth just
south of the ice-covered
polar seas in the Northern
Hemisphere
Cold and dark much of
the year
 winters
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extremely long, cold,
and harsh
summers
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short (6–8 weeks)
1. Tundra
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Rainfall amounts to only about
20 cm per year
 Only the topmost layer of
soil thaws
 permafrost beneath this
layer is always frozen
Trees are not found in the
tundra
 Growing season too short
and roots cannot penetrate
permafrost
2. Coniferous forests
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Coniferous forests are found in
three locations:
 Taiga
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Near mountaintops
 Along the Pacific coast of
North America
Taiga forest exists south of the
tundra
 Needlelike leaves of its conebearing trees can withstand
the weight of heavy snow
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extends around the world in
the northern part of North
America and Eurasia
2. Coniferous forests
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Temperate rain forest
 Coniferous forest that
runs along the west
coasts of Canada and
the United States
 Plentiful rainfall and
rich soil
3. Temperate deciduous forests
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Found south of the taiga
in eastern North America,
eastern Asia, and much
of Europe
Seasons are well defined
Growing season ranges
between 140 and 300
days
3. Temperate deciduous forests
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Trees have broad leaves and
are deciduous
 Lose their leaves in fall and
grow them in spring
Tallest trees form a canopy
Autumn fruits, nuts, and
berries provide food for the
winter
Leaves contribute to a rich
layer of humus
4. Temperate grasslands
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Bitterly cold winters and hot
and dry summers
Across the United States from
east to west
 Temperate deciduous
forest transitions into tall-
grass prairie
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Requires more rainfall than
does the short-grass prairie
(occurs near desert)
Large herds of bison
Small mammals, (mice, prairie
dogs, and rabbits) live below
ground, but usually feed
aboveground
Savannas
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In regions where a cool dry
season is followed by hot rainy
season
 Largest savannas are in
central and southern Africa
 Australia, Southeast Asia,
and South America
 Characterized by large
expanses of grasses with
sparse populations of trees
 Plants have extensive and
deep root systems that
enable them to survive
drought and fire
Savannas
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African savanna
 Greatest variety and
number of large
herbivores
 Elephants and
giraffes - tree
vegetation
 Antelopes, zebras,
wildebeests, water
buffalo, and some
rhinoceroses - grasses
5. Deserts
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Northern and Southern Hemispheres
 Winds that descend in these
regions lack moisture
 Annual rainfall is less than 25 cm
 Lack of cloud cover
 Nights are cold because heat
escapes easily into
atmosphere
 Most have plants highly adapted
to survive long droughts, extreme
heat, and extreme cold
 Some animals are adapted to the
desert environment
 Nocturnal or burrowing
6. Tropical rain forests
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South America, Africa, and
the Indo-Malayan
 Temperature is always
warm (20° to 25°C)
 Rainfall is plentiful
(minimum of 190
cm/year)
May be the richest
ecosystem
 Diversity of species is
enormous
 10 km2 area of
tropical rain forest
may contain 1,500
species of flowering
plants
Tropical rain forests
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Complex structure with three levels:
 Canopy
 Sunlight is filtered out
 Plants of the forest floor are
tolerant of minimal light
 Understory
 Consists of shorter trees
 receive some light and bear
epiphytes
 Plants that grow on other
plants
 usually have roots of their
own
 Forest floor
 Insects are abundant
 majority of species have not
been identified
Topography
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Surface features of land
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Mountains
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topographic features that
affect climate and
distribution of ecosystems
Difference between the
windward side and the
leeward side can be quite
dramatic
Hawaiian Islands
Topography
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Elevation affects the
distribution of terrestrial
ecosystems
Nearby Bodies of Water
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Ocean temperature is more
stable than landmasses
Ocean water gains or loses
heat more slowly than
terrestrial environments
Monsoon climate
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wet ocean winds blow
onshore for almost half
the year
Fresh Water and Salt Water
Are Organized into
Aquatic Ecosystems
Fresh water flows into salt water
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Fresh water
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flows within streams and rivers
contained in lakes and ponds
Wetlands directly absorb storm waters and overflows from lakes and
rivers
 protect farms, cities, and towns from the devastating effects of
floods
Types of lakes
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Lakes are often classified
by nutrient status
 Oligotrophic lakes
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Nutrient-poor
Have a small amount of
organic matter and low
productivity
Eutrophic lakes
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Nutrient-rich
Have plentiful organic
matter and high
productivity
Marine ecosystems
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Estuary
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Partially enclosed body of
water where fresh water and
sea water meet and mix as a
river enters the ocean
Organisms must be able to
withstand constant mixing of
waters and rapid changes in
salinity
Nearly two-thirds of marine
fishes and shellfish spawn
and develop in the protective
and rich environment of
estuaries
Marine ecosystems
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Intertidal zone
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Lies between the high
and low tide marks
Rocky shores and
sandy shores are
constantly bombarded
by the sea as the tides
roll in and out
Oceans
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Shallow ocean waters (euphotic
zone) contain a greater
concentration of organisms than
the rest of the sea
Coral reefs
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Areas of biological abundance
just below the surface in
shallow, warm, tropical waters
Most of the ocean lies within the
pelagic zone
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Epipelagic zone
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Mesopelagic zone
Bathypelagic zone
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lacks the inorganic nutrients
of shallow waters
complete darkness
Abyssal plain
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many invertebrates survive there
by feeding on debris floating
down from the mesopelagic
zone
Oceans
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Ocean inhabitants in
divisions of pelagic zone
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Epipelagic zone
Mesopelagic zone
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Animals in the deeper waters
here are carnivores
are adapted to the absence of
light
Bathypelagic zone
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in complete darkness except for
an occasional flash of
bioluminescent light
Ocean currents affect climates
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Climate is driven by the sun
oceans play a major role in redistributing heat in the
biosphere
 Air takes on the temperature of the water below
 Warm air moves from the equator to the poles
 The oceans make the winds blow
Ocean Currents
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Because the ocean currents
eventually strike land, they move in
a circular path
 Clockwise in the Northern
Hemisphere
 Counterclockwise in the
Southern Hemisphere
As the currents flow, they take warm
water from the equator to the poles
 Gulf Stream
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brings tropical Caribbean water
to the east coast of North
America and the higher latitudes
of western Europe