energy

• producers

  • convert light energy into chemical energy- stored in biological molecules
  • rate of this conversion is the primary productivity
• gross primary producitivty(GPP)

  • rate at which chemical energy is converted into carbohydrates
• net primary productivty

  • rate at which energy is stored in plant biomass
• NPP=GPP-respiration

  GPP=NPP+R

  • NPP presents the energy which is available to organisms at a higher trophic level
  • NPP=units of energy per unit area/ volume per unit time
  • JM-2yr-1=joules per m2 per year