Energy Flow and Trophic Structure

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Energy Flow and Trophic Structure

• Chapter 14

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Energy Capture

• Heterotrophs obtain energy from organic sources
  or from other organisms
• Autotrophs obtain energy from inorganic sources
• Photoautotrophs and chemoautotrophs

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Energy Capture and Use

• Photosynthesis and respiration
• Photosynthesis
• 6 CO2 6 H2O -gt C6H12O6 6O2
• Respiration
• C6H12O6 6O2 -gt 6 CO2 6 H2O
• Primary production energy capture via
  photosynthesis into organic molecules
• Biomass amount of E stored in dry weight of
  organic matter

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Energy, Production and Biomass

• Standing crop biomass fraction of total biomass
  in living plant tissue
• Gross primary production total rate of energy
  accumulation
• Net primary production gross primary production
  minus respiration

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Factors for Production

• Light
• Water
• Temperature
• Nutrients
• Factors interact to determine production

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Trophic structure

• Food chain
• Plants -gt herbivores -gt carnivores -gt top
  carnivore
• Primary producers -gt primary consumers -gt
  secondary consumers -gt tertiary consumers etc -gt
  decomposers
• Each is a trophic level
• Food webs
• Connectance of actual interactions of total
  possible interactions

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Food webs, chains and pyramids

• Eltonian pyramids all species feeding at a
  trophic level are lumped together
• Can be in terms of numbers, biomass, or energy
  content
• Food chain lengths are determined by of trophic
  structures in a system
• Top-down Vs. bottom-up effect trophic cascade

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The End!