What is primary productivity? Give a brief description of the factors that affect primary productivity.

The amount of biomass produced per unit area over a period of time by plants, during photosynthesis is called primary productivity. It includes gross primary productivity (GPP) and net primary productivity (NPP).

• GPP: It is the rate of production of organic matter during photosynthesis.
• NPP: Gross primary productivity minus respiratory loss (R) is NPP. NPP = GPP-R.

Factors affecting the primary productivity are sunlight, water, nutrients, temperature and carbon dioxide.