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

Explanation

Primary productivity is defined as the amount of biomass or organic matter produced per unit area over a period of time by plants, during photosynthesis. It can be divided into Gross-Primary Productivity (GPP) and Net Primary Productivity (NPP).
a) Gross Primary Productivity : Of an ecosystem is the rate of production of organic matter during photosynthesis. A considerable amount of GPP is utilized by plants for their catabolic process (respiration).
b) Net Primary Productivity : Gross Primary Productivity. minus respiratory loss (R), is the Net Primary Productivity (NPP). On average about 20-25 percent of GPP is used for the catabolic (respiratory) activity.
GPP-R = NPP
The Net Primary productivity is the biomass available for the consumption of the heterotrophs (herbivores and decomposer).