Primary and secondary productivity is the rate of primary or secondary production, measured as biomass in a given area in a given time (eg kJ ha⁻¹ year⁻¹)
Productivity measures how fast an organism builds up biomass. Primary productivity applies to plants; secondary productivity applies to animals. Both use units of energy per area per year.
Real World
Coral reefs have a net primary productivity of around 2 500 g C m⁻² year⁻¹, rivalling tropical rainforests, which is why marine biologists call them the 'rainforests of the sea'.
Exam Focus
Always include a time component in units (e.g. kJ ha⁻¹ year⁻¹) — productivity is a rate, and omitting time loses marks.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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