Primary production

Definition

The synthesis of organic compounds from inorganic carbon sources, principally via photosynthesis (using light energy) or chemosynthesis (using chemical energy), by autotrophic organisms that form the energetic base of food webs. In terrestrial systems, plants are the dominant primary producers; in aquatic systems, algae and cyanobacteria predominate. Ecologists distinguish gross primary production (total carbon fixation) from net primary production (remaining after autotrophic respiration).

Etymology

Example

Aphid population dynamics in a cereal field depend directly on the rate of primary production by the wheat canopy, as phloem sap availability limits reproductive output; similarly, detritivorous millipedes in forest litter rely on the throughput of net primary production that eventually enters the decomposition pathway.

Synonyms

• primary productivity

Related Terms

• Autotroph
• Trophic level
• Net primary production
• gross primary production
• Photosynthesis
• chemosynthesis
• Food web
• herbivory
• detritivory

Usage Notes

Often used in the mass noun sense ("primary production in the meadow"); "productivity" is sometimes preferred when emphasizing rate per unit area or time. Net primary production is the biomass or energy actually available to heterotrophs, including insects and other arthropods, after plant metabolic costs. Contrast with secondary production (biomass generation by consumers).