The Carbon Cycle

• Elements are cycled back to the start of the food chain by decay
• Why do materials break down?

  Microorganisms digest them
• What are the best conditions for decay?

  • warm
  • moist
  • aerobic (oxygen rich)
• Where does decay put materials back?

  The soil
• In a stable community, materials are constantly cycled through the food chain
• Steps of the carbon cycle:

  • CO2 removed from atmosphere during photosynthesis
  • Plants and algae respire, some carbon is returned
  • Plants and algae eaten- carbon becomes part of the fats and proteins in the animal
  • Animals respire- carbon is returned
  • Plants, algae and animals die- microorganisms feed on them and produce carbon dioxide
  • Waste from animals is also broken down by microorganisms
  • Combustion of wood and fossil fuels releases carbon dioxide