Basic Ecology I
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Energy
Types of Ecosystems
Productivity
Energy Flow
Trophic levels
Food webs/chains
Energy: the ability to do work
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Moving matter over a distance/ a heat transfer between two objects
Kinetic energy: energy contained in moving objects
Potential energy: stored energy
Heat: energy transferred between objects
High and Low quality energy: concentrated versus diffused
Ie, wind compared to oil
Thermodynamics
• 1st law: energy is
conserved
• 2nd law: with energy
transfer, less energy
becomes available
Potential and kinetic energy
Energy and Ecosystems
Chemosynthesis
Ecosystems
Productivity
• Limits to Primary
production
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Light
Nutrients
Water
Temperature
Energy Source for Ecosystem
• Energy flows through
ecosystem
• Not recycled like
matter
• Continuous supply
• Solar energy
• Enters ecosystem
through
photosynthesis
Equations for production
• Biomass 1 = biomass 2 – NP (net production)
• Three currencies of energy flow: biomass,
energy content, carbon content
Trophic levels
• Autotrophs
(Producers)
• Heterotrophs
(Consumers)
• Detritivores
(Decomposers)
Trophic levels
• Autotrophs
(Producers)
• Heterotrophs
(Consumers)
• Detritivores
(Decomposers)
Chemosynthetic
Light is not the source of energy
Energy & Biomass
Energy and Biomass
Food Chains/Webs
Aquatic Food webs
Limits to Food Chain Length
• Energetic Hypothesis
• Inefficiency of energy
transfer
• 10% rule
• Dynamic stability
hypothesis (length of
chain)
Applications
Biomagnification
Toxic materials: DDT, Hg, Pb
Human trophic Level
Dependent of where we
Eat in the food chain.
Should Humans eat lower on the
Food Chain?
Summary
• Energy determines the limits of the food
supply
• Energy is fixed by autotrophs
• Energy flow between levels depends on
the efficiency of energy transfer