ECOLOGY

The SHORT versionBioH Ch 41

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Energy Flow

PRODUCERS

AutotrophsPhotosynthesisChemosynthesis

Energy flows THROUGH an ecosystem

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Consumers Heterotrophs Herbivores Carnivores Omnivores Detritivores Decomposers

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Food Chain

Energy relationship between organisms in ecosystem4

Food Web

Trophic Levels5

Trophic Levels

Specific level (relationship) that an

organism occupies in a food chain

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Ecological Pyramids

Energy PyramidShows relative amount of energy available at each trophic level

Only 10% of available energy transferred from one trophic level to the next

• Energy• Biomass• Pyramid of numbers

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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 CyclesBiological, geological, & chemical matter recycled through ecosystems

WATER CYCLE

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Nutrient Cycles

Carbon Cycle

Biological processes (photosynthesis, respiration, decomposition) take up & release carbonGeochemical processes (erosion, volcanic activity) release CO2 into the atmosphereMixed processes (burial & decomposition of dead organisms converting to petroleum) store carbon undergroundHuman activities (mining, forestation, burning fossil fuels) release CO2 into atmosphere

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Nitrogen Cycle All organisms require nitrogen to build proteinsN2 is in atmosphereNitrogen fixation – bacteria convert N2 to NH3 in soil, used as nutrients for producersDenitrification – bacteria convert NH3 to N2 in atmosphere

Used in forming DNA/RNANot in atmosphere, just soil and water

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Limiting FactorsPrimary productivity Rate at which organic matter is created by producers

Limiting factors Abiotic - ???Biotic - ???

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Ecosystem Modeling

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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

OVERVIEW

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