Functions of ecosystem includes
(i) productivity
(ii) decomposition
(iii) energy flow
(iv) Nutrient cycling

·  Productivity refers to the rate of biomass production. It is expressed interms of (g⁻²) yr⁻¹ / (Kcal m⁻²)yr⁻¹ to compare the productivity of different ecosystem.

·  Productivity is of three types
(i) Primary productivity → Gross primary productivity, Net primary productivity
(ii) Secondary productivity
(iii) Community productivity

·  1° productivity is the amount of biomass (or) organic matter produced per unit area over a time period by plants during photosynthesis.

·  Gross primary productivity (GPP) is the rate of energy production by green plants (producers) per unit area per unit time. Productivity is expressed in terms of weight (g⁻² yr⁻¹) or energy (Kcal m⁻² yr⁻¹)

·  Net primary productivity is the energy left after respiration and stored / buildup in their bodies per unit time and area. NPP = GPP−R Net productivity is equal to grass primary productivity minus loss due to respiration and other reasons.

·  Secondary productivity is the rate of assimilation of the food energy available at the level of consumers (or) heterotrophs per unit time and area. It is the amount of energy available at the consumer level for the transfer to the next trophic level.

·  community productivity is the rate of net synthesis of build up of organic matter by a community per unit area and time.