Transcript 34. The Biosphere: An Introduction to Earth`s Diverse Environments

Chapter 34
The Biosphere: An
Introduction to Earth's
Diverse Environments
PowerPoint Lectures for
Biology: Concepts and Connections, Fifth Edition
– Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
A Mysterious Giant of the Deep
• Deep-sea submersibles are revealing the
diversity of life beneath the ocean
– Giant squid
– Hydrothermal vent communities
• Animals, such as tube worms, living on
energy produced by chemoautotrophic
bacteria
• Ecology is the scientific study of the
interactions of organisms with their
environments
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Video: Hydrothermal Vent
Video: Tubeworms
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34.1 Ecologists study how organisms interact
with their environment at several levels
• Organism
– Individual organisms interacting with the
environment
• Population
– Group of individuals of the same species
living in a particular geographic area
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• Community
– All the populations of different species that
inhabit a particular area
• Ecosystem
– All the biotic and abiotic components in a
certain area
• Ecological research is conducted in the field as
well as in the lab and with models
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THE BIOSPHERE
34.2 The biosphere is the total of all of Earth's
ecosystems
• The biosphere is the global ecosystem
– Atmosphere to an altitude of several
kilometers
– Land down to 3,000 m beneath Earth's
surface
– Oceans to a depth of several kilometers
• The biosphere is self-contained and
characterized by patchiness
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CONNECTION
34.3 Environmental problems reveal the limits of
the biosphere
• No part of the biosphere is untouched by
human activities
• Current awareness of the biosphere's limits
stems from past environmental practices
– Rachel Carson warned of the effects of
pesticides in 1962
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34.4 Physical and chemical factors influence life
in the biosphere
• Major abiotic factors determine the biosphere's
structure and dynamics
– Solar energy
– Water
– Temperature
– Wind
– Disturbances such as fire, hurricanes
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34.5 Organisms are adapted to abiotic and biotic
factors by natural selection
• Species exist in a given place because they
evolve there or disperse there
• Unique adaptations that fit a particular
environment allow organisms to survive there
– Example: pronghorns
• Organisms vary greatly in their ability to
tolerate fluctuations and long-term changes in
their environment
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34.6 Regional climate influences the distribution
of biological communities
• Because of its curvature, Earth receives an
uneven distribution of solar energy
• The tilt of the Earth's axis causes the seasons
of the year
– Globe's position relative to the sun changes
through the year
– The tropics experience the least seasonal
variation in solar radiation
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LE 34-6a
North Pole
60°N
Low angle of
incoming sunlight
30°N
Tropic of
Cancer
Sunlight strikes
most directly
0° (equator)
Tropic of
Capricorn
30°S
Low angle of
incoming sunlight
Atmosphere
60°S
South Pole
LE 34-6b
March equinox
(equator faces
sun directly)
June solstice
(Northern
Hemisphere tilts
toward sun)
Constant tilt
of 23.5°
September
equinox
December
solstice
(Northern
Hemisphere tilts
away from sun)
• Uneven heating of the Earth sets up patterns
of precipitation and prevailing winds
– Doldrums are near the equator
– Trade winds dominate the tropics
– Seasonal climate variation and more
moderate temperatures exist in the
temperate zones
– Prevailing winds are major global air
movements
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LE 34-6c
Descending
dry air
absorbs
moisture
Trade winds
Ascending
moist air
releases
moisture
Descending
dry air
absorbs
moisture
Trade winds
Doldrums
0°
Temperate
zone
Tropics
Temperate
zone
LE 34-6d
60°N
30°N
30°S
• Ocean currents have a profound effect on
regional climates
– Generally modify climate of nearby land
• Landforms can also affect local climate
• Variations in climate determine the character of
the world's biomes
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LE 34-6e
Fresno
104°
40 miles
Death
Valley
119°
Paso Robles
Bakersfield
93°
106°
Pacific Ocean
Burbank
86°
Santa Barbara 75°
Key
70s (°F)
80s
Los Angeles
(Airport) 74°
Riverside 91°
Santa Ana
Palm Springs 104°
84°
90s
100s
110s
San Bernardino 101°
San Diego 75°
LE 34-6f
Wind
direction
East
Pacific
Ocean
Sierra
Nevada
Coast
Range
AQUATIC BIOMES
34.7 Oceans occupy most of Earth's surface
• Abiotic factors influencing the distribution of
aquatic biomes
– Light
– Distance from shore
– Availability of nutrients
• Oceanic zones
– Intertidal zone: where land meets ocean
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– Pelagic zone: open ocean
• Contains phytoplankton and zooplankton
– Benthic zone: seafloor
– Photic zone: illuminated regions of the
pelagic and benthic zones
• Photosynthesis occurs
– Aphotic zone: vast, dark region underlying
the photic zone
• Most extensive part of the biosphere
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LE 34-7b
Intertidal zone
0
Photic zone
200 m
Pelagic
zone
Continental
shelf
Benthic zone
(seafloor)
2,500–6,000 m
Aphotic
zone
• Continental shelf: submerged part of a
continent
• Coral reef: found in warm waters above
continental shelf
– Biologically very diverse
• Estuary: area where freshwater stream or river
merges with ocean
– Among the most productive biomes on
Earth
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• Wetland: area that is transitional between an
aquatic and terrestrial ecosystem
• Aquatic communities are environmentally
threatened
Video: Coral Reef
Video: Clownfish and Anemone
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34.8 Freshwater biomes include lakes, ponds,
rivers, streams, and wetlands
• Light has a significant effect on freshwater
biomes
– All but the most shallow ponds and lakes
have photic and aphotic zones
• Temperature creates stratification of water
• Availability of nutrients and dissolved oxygen
influence organic growth
– Nitrogen and phosphorus runoff create algal
blooms
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• Rivers and streams support communities quite
different from those of lakes and ponds
• Freshwater wetlands range from swamps to
marshes and bogs
– Great ecological and economic value
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TERRESTRIAL BIOMES
34.9 Terrestrial biomes reflect regional variations
in climate
• Many biomes are named for climatic features
and predominant vegetation
• Each biome is also characterized by the
organisms adapted to that environment
• The distribution of biomes depends largely on
climate
• Within each biome there is local variation
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LE 34-9
30°N
Tropic of
Cancer
Equator
Tropic of
Capricorn
30°S
Tropical forest
Temperate grassland
High mountains
Savanna
Temperate broadleaf forest
Polar ice
Desert
Coniferous forest
Chaparral
Tundra
34.10 Tropical forests cluster near the equator
• Rainfall generally determines the type of
vegetation in a tropical forest
• Tropical rain forests are the most complex of
all biomes
– Very high diversity
– Complex structure
– Human impact is of great concern
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34.11 Savannas are grasslands with scattered
trees
• Savannas are dry and warm
– Frequent fires inhibit invasion by trees
– Large grazing animals migrate during
seasonal droughts
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34.12 Deserts are defined by their dryness
• Deserts are the driest terrestrial biomes
– Can be hot or cold
– Cycles of growth and reproduction are
keyed to rainfall
– Animals are adapted to drought and
extreme temperatures
• Desertification is a significant environmental
problem
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34.13 Spiny shrubs dominate the chaparral
• The chaparral is a region of dense, spiny
shrubs with tough, evergreen leaves
– In midlatitude coastal areas
– Cool, rainy winters and dry, hot summers
– Vegetation adapted to periodic fires
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34.14 Temperate grasslands include the North
American prairie
• Temperate grasslands are found where winters
are cold
– Similar to savannas but mostly treeless
– Periodic drought, fires, and grazing inhibit
growth of woody plants
– Amount of annual rainfall influences height
of vegetation
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34.15 Broadleaf trees dominate temperate
forests
• Temperate broadleaf forests grow throughout
midlatitude regions
– Need sufficient moisture to support the
growth of large trees
– Mix of tree species depends on abiotic
factors
• Most original North American broadleaf forests
were destroyed by logging, agriculture, and
development
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34.16 Coniferous forests are often dominated by
a few species of trees
• Cone-bearing trees dominate northern
coniferous forest, or taiga
– Found where there are short, wet summers
and long, cold winters
• Logging is eliminating old-growth coniferous
trees
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34.17 Long, bitter-cold winters characterize the
tundra
• Arctic tundra is a treeless biome
– Found at the northernmost limits of plant
growth and at high altitudes
– Characterized by extreme cold, wind, and
permafrost
– Animals have good insulation that retains
heat
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TALKING ABOUT SCIENCE
34.18 Ecologist Ariel Lugo studies tropical forests
in Puerto Rico
• The Luquillo Experimental Forest allows
ecologists to study the effects of disruption on
tropical forests
– Mirrors other tropical forests
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• Dr. Ariel Lugo tempers his concerns about rain
forest organisms with an understanding of the
social and economic needs of the people there
– Important to integrate all legitimate claims
on the forest
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