Transcript BioH Ch 41 Ecosystems

ECOLOGY
The SHORT version
BioH Ch 41
1
Energy Flow
PRODUCERS
 Autotrophs
 Photosynthesis
 Chemosynthesis
Energy flows THROUGH
an ecosystem
2
Consumers
 Heterotrophs
 Herbivores
 Carnivores
 Omnivores
 Detritivores
 Decomposers
3
Food Chain
Energy relationship between organisms in ecosystem
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Food Web
Trophic Levels
5
Trophic Levels
Specific level
(relationship) that an
organism occupies in a
food chain
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Ecological Pyramids
• Energy
• Biomass
• Pyramid of numbers
Energy Pyramid
Shows relative amount
of energy available at
each trophic level
Only 10% of
available energy
transferred from
one trophic level to
the next
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Biomass
Pyramid
Represents amount
of living organic
matter at each level
10% transferred
between levels
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Pyramid of Numbers
Relative number of organisms
at each trophic level
Only about 10% transferred
between levels
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Pyramid of Numbers for oak tree community
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Biogeochemical Cycles
Biological,
geological, &
chemical matter
recycled through
ecosystems
WATER CYCLE
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Nutrient Cycles
Carbon Cycle
Biological processes
(photosynthesis, respiration,
decomposition) take up & release
carbon
Geochemical processes (erosion,
volcanic activity) release CO2 into the
atmosphere
Mixed processes (burial &
decomposition of dead organisms
converting to petroleum) store
carbon underground
Human activities (mining,
forestation, burning fossil fuels)
release CO2 into atmosphere
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Used in forming DNA/RNA
Not in atmosphere, just soil
and water
Nitrogen Cycle
 All organisms require nitrogen
to build proteins
N2 is in atmosphere
Nitrogen fixation – bacteria
convert N2 to NH3 in soil, used as
nutrients for producers
Denitrification – bacteria
convert NH3 to N2 in atmosphere
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Limiting Factors
Primary productivity
 Rate at which organic matter is created by producers
Limiting factors
 Abiotic - ???
Biotic - ???
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Ecosystem Modeling
Through the use of computers, the attempt to model an
ecosystem in order to predict what might happen to that
ecosystem (or the species within it) if some modification to
the ecosystem happens.
An example: DDT biological
magnification (an increase in the
concentration of a substance that
occurs in a food chain as a result
of:
• Persistence
• Food chain energetics
• Low rate of degradation
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OVERVIEW
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