Question

Which of the following is expected to have the highest value (gm/m2/yr) in a grassland ecosystem?

• A. Secondary productivity
• B. Tertiary productivity
• C. Gross primary productivity (GPP)
• D. Net primary productivity (NPP)

Answer 1

The correct option is C

Gross primary productivity (GPP)

Gross primary productivity or GPP is the rate at which organic matter is synthesized per unit area per unit time by producers. Amount available for the heterotrophs is called net primary productivity or NPP. NPP is a measure of the remaining energy or biomass left after meeting the cost of respiration and maintenance for the producers. Secondary productivity is the rate of formation generation of new biomass by heterotrophic organisms or consumers. Gross primary productivity will have highest value in a grassland ecosystem as the producers i.e grass will be in abundance and very little expenditure is there in terms of respiration and other metabolic requirements.