Agricultural ecosystems

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What is an agricultural ecosystem?

  • Made up of domesticated animals/plants
  • Make food for humans
  • Energy is usually lost as humans are 3rd-4th trophic level
  • Eradicate other species
  • Considerable energy losses must be prevented
  • Ensure as much energy as possible is channelled into human food chains
  • Away from other food chains
  • Increases productivity of food chain
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What is productivity?

  • Rate at which something is produced
  • Producers convert light energy into chemical energy
  • Rate at which this is absorbed/digested is GROSS PRODUCTIVITY
  • 20% energy used in respiration of plant
  • Remainder is NET PRODUCTIVITY
  • Net productivity= gross productivity(kJm  year  )x respiratory losses
  • Net productivity is affected by:
    • Efficiency of crop at carrying out photosynthesis
    • Area of ground covered by crop leaves
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Comparing Natural and Agricultural ecosystems

Natural Ecosystems  Agricultural Ecosystems

  • No additional energy input- only solar energy
  • Lower productivity
  • More species diversity
  • More genetic diversity
  • Natural recycling of nutrients
  • Populations are controlled by natural means (competition and climate)
  • Natural climax community
  • Solar energy+Fossil fuels+labour= Additional enrgy input
  • Higher productivity
  • Less species diversity
  • Less genetic diversity
  • Limited natural recycling of nutrients- supplemented by fertilisers
  • Populations are controlled by use of pesticides as well as natural means
  • Prevented from reaching natural climax
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