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Which of the following is expected to have the highest value (gm/m$^2$/yr) in a grassland ecosystem : -
A
Tertiary production
B
Gross production (GP)
C
Net production (NP)
D
Secondary production
Detailed Solution
Gross primary production (GPP) is the total rate at which producers fix solar energy as organic matter by photosynthesis.
Net primary production (NPP) = GPP $-$ respiration losses of the plants. So NPP is always less than GPP.
Only a small part (about 10 percent) of the energy of one trophic level passes to the next. So secondary production (by herbivores) is much less than NPP, and tertiary production (by carnivores) is even less.
So the order is: GP $\gt$ NP $\gt$ secondary production $\gt$ tertiary production.
The highest value is that of gross production (GP).
Net primary production (NPP) = GPP $-$ respiration losses of the plants. So NPP is always less than GPP.
Only a small part (about 10 percent) of the energy of one trophic level passes to the next. So secondary production (by herbivores) is much less than NPP, and tertiary production (by carnivores) is even less.
So the order is: GP $\gt$ NP $\gt$ secondary production $\gt$ tertiary production.
The highest value is that of gross production (GP).