Energy transfer and productivity

• Gross primary productivity is the total quantity of energy that the plants in a community convert into organic matter
• Net primary productivity is the rate at which plants store energy
• Net production is calculated by subtracting respiratory losses from gross production
• Why there is low energy transfer between the trophic levels

  • part of the organism isn't eaten
  • some parts can't be digested and are lost in faeces
  • energy lost in waste
  • energy lost as heat from respiration
• Net production of consumers is calculated by the chemical energy of the ingested food minus (energy lost in faeces plus respiratory losses)