State the relation between gross and net primary productivity.

The relation between the gross and net primary productivity can be shown as:

(a) Gross primary productivity is the rate of production of organic matter during photosynthesis.

(b)Net primary productivity is the available biomass for the consumption to heterotrophs (herbivores or decomposers).

Gross primary productivity minus the respiratory losses is the net primary productivity

NPP = GPP-R, where,

NPP = Net primary productivity

GPP = Gross primary productivity

R = Respiration