Biology, Seventh Edition
Solomon • Berg • Martin
Chapter 53
Ecosystems and the
Biosphere
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Energy flow through an
ecosystem
• Linear
• Sun to producer to consumer to
decomposer
• Trophic relationship may be
expressed as food chains or as
food webs
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
Energy flow through an ecosystem
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Ecological pyramids
• Express the progressive reduction
in numbers of organisms, biomass,
and energy found in successive
trophic levels
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
Pyramids of biomass
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Gross primary productivity (GPP)
• Rate at which photosynthesis
captures energy
• Net primary productivity (NPP)
• Energy that remains after plants
and other producers carry out
cellular respiration
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
NPP for selected
ecosystems
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Carbon cycle
• Carbon dioxide is the most
important gas
• Carbon enters plants, etc., as CO2
• Cellular respiration, combustion,
and erosion of limestone return
CO2 to the environment
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
Carbon cycle
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Nitrogen cycle
• Five steps
–Nitrogen fixation
–Nitrification
–Assimilation
–Ammonification
–Denitrification
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
Nitrogen cycle
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Phosphorus cycle
• Phosphorus erodes from rock as
inorganic phosphate
• Animals obtain it from their diet
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
Phosphorus cycle
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Hydrologic cycle
• Renews the supply of water
• Involves an exchange of water
between the land, ocean,
atmosphere, and organisms
• Water enters the atmosphere by
evaporation and transpiration
• Water leaves the atmosphere as
precipitation
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
Hydrologic cycle
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Bottom-up processes
• Availability of resources such as
nutrient minerals controls the
number of producers, which
controls the number of herbivores,
etc.
• Top-down processes
• An increase in top predators
cascades down the food web
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Sunlight primary source of
energy
• Combination of Earth’s spherical
shape and its axis tilt concentrate
solar energy at the equator
• Inclination of Earth’s axis primarily
determines the seasons
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
Seasonal changes in temperature
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Visible light and infrared
radiation warm the surface and
lower part of the atmosphere
• Atmospheric heat produces air
movement, which moderates the
climate
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
Atmospheric circulation
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
Major surface ocean currents
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Coriolis effect
• Tendency of moving air or water to
be deflected
–Right in the Northern Hemisphere
–Left in the Southern Hemisphere
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Regional precipitation
differences
• Influenced by latitude, elevation,
topography, vegetation, distance
from large bodies of water, and
location
• Precipitation greatest where warm
air passes over the ocean and
then cools
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
Rain shadow
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Biology, Seventh Edition
CHAPTER 53 Ecosystems and the Biosphere
• Effect of fire on certain
ecosystems
• Fire frees the nutrient minerals
locked in organic matter, removes
plant cover, and increases erosion
• Many ecosystems, such as
savanna, chaparral, grasslands,
and certain forests, contain fireadapted organisms
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