Question

Write an explanatory note on: Productivity.

Hint:

Productivity is a rate; separate the total made (GPP) from what is left after the plant's own respiration (NPP).

Answer 1

Step 1: Understanding the Concept:
An ecosystem's productivity is a measure of how fast new organic matter (biomass) is being created, and this happens mainly through the photosynthesis of green plants.

Step 2: Define primary productivity.
Primary productivity is defined as the rate of biomass or organic matter production per unit area over a period of time, by plants during photosynthesis.

Step 3: Split it into gross and net.
Gross Primary Productivity (GPP) is the total rate of production of organic matter, before any of it is used up by the plant's own respiration.
Net Primary Productivity (NPP) is what remains after subtracting the plant's own respiratory losses from GPP, and it is this NPP that is actually available to herbivores and the rest of the food chain.

Final Answer:
Productivity, specifically primary productivity, is the rate at which plants produce biomass; GPP is the total amount produced, and NPP is GPP minus what the plant itself uses up in respiration.