5-3-5-net-primary-production

Net primary production

• Net primary production (NPP) can be defined as

the chemical energy stored in plant biomass after respiratory losses to the environment have been taken into account

• Plants convert light energy to chemical energy in the form of glucose during photosynthesis; the total energy stored in this way is gross primary production (GPP)

• Some of the energy stored during GPP is lost to the environment, e.g. when waste heat is generated during respiration

• The energy that remains in the plant tissues after these energy losses is the NPP

  • NPP is important because it represents the energy that is available to consumers in the ecosystem

• Net primary production can therefore be calculated as follows:

NPP = GPP – R

• Where:

  • GPP = gross primary production

  • R = respiratory loss to the environment

• NPP, like GPP, is expressed as energy per unit area or volume, e.g.:

  • J m^–2

  • J m^–3