Question

Which among the following equations relating to productivity of an ecosystem is/are correct and can be used to calculate a required entity of productivity?
I. GPP-R = NPP
II. GPP= NPP+R
III. GPP-NPP = R
IV. GPP = NPP/R

• A. Only I
• B. Only III
• C. I and II
• D. I, II and III

Answer 1

The correct option is D I, II and III

Amount of organic matter produced per unit area over a time period by plants through the process of photosynthesis is called primary productivity.

Gross primary productivity (GPP): rate of production of organic matter during photosynthesis. A considerable amount of which is utilised by plants in respiration (R)

Net primary productivity (NPP): The gross primary productivity left after respiration, which is stored as organic matter in the producers, per unit area per unit time.

So, Net primary can be written
GPP-R= NPP.
This can also be written as
GPP= NPP+R.
Similarly, respiratory losses R can be calculated by deducting NPP from GPP i.e. GPP-NPP= R.