Productivity: GPP − R = NPPउत्पादकता: GPP − R = NPP

NCERT Section 12.2 · Class 12 Biology · Chapter 12 · interactive diagram

Parts and their functions

• Sunlight (सूर्य का प्रकाश) — A constant input of solar energy is the basic need of every ecosystem.
• Gross primary productivity (GPP) (सकल प्राथमिक उत्पादकता (GPP)) — Rate of production of organic matter during photosynthesis.
• Respiration loss (R) (श्वसन हानि (R)) — A considerable part of GPP is used by the plants themselves in respiration.
• Net primary productivity (NPP) (निवल प्राथमिक उत्पादकता (NPP)) — GPP minus respiration losses. It is the biomass available to heterotrophs (herbivores and decomposers).
• Herbivores (शाकाहारी) — Consume part of the NPP.
• Decomposers (अपघटक) — Also use NPP (dead plant matter).
• Secondary productivity (द्वितीयक उत्पादकता) — Rate of formation of new organic matter by consumers.
• Annual NPP of the biosphere (जीवमंडल की वार्षिक NPP) — About 170 billion tons (dry weight) of organic matter every year.
• Oceans: 55 billion tons (महासागर: 55 अरब टन) — Oceans occupy about 70% of the surface, yet their productivity is only 55 billion tons.
• Land: the rest (स्थल: शेष) — The rest of the 170 billion tons (about 115) is produced on land.

Steps

1. Plants trap sunlight and make organic matter: gross primary productivity (GPP).
2. Part of GPP is used up in the plants’ own respiration (R).
3. What remains is NPP: GPP − R = NPP.
4. NPP is food for herbivores and decomposers; consumers then make new organic matter (secondary productivity).
5. Whole biosphere: about 170 billion tons a year — oceans only 55 billion tons.

Original diagram drawn by Simple Learning Hub, based on NCERT Section 12.2. Report a mistake