Key Points

1. Primary vs Secondary Production:

• Primary production refers to energy transfer at the producer level (plants and photosynthesis).
• Secondary production occurs at the consumer level (herbivores, carnivores, etc.).

2. Energy Transfer:

• Only a small proportion of the energy from plants is converted into biomass by animals.
• Energy losses occur due to:
• Respiration (energy lost as heat).
• Egestion (energy lost in faeces).
• Excretion (energy lost in urine).
• Undigested material.

3. Gross Secondary Productivity (GSP):

• The total energy gained by consumers from their food.
• Formula:

4. Net Secondary Productivity (NSP):

• The energy that remains after losses (e.g., respiration) and is converted into biomass.
• Formula:

5. Efficiency of Energy Transfer:

• Efficiency (%) =

• Transfer efficiency is usually low due to significant energy losses at each trophic level.

Summary

• Secondary productivity is crucial for understanding energy flow within ecosystems and ensuring efficient resource management in agriculture and conservation.
• Energy losses at each trophic level explain why food chains are relatively short, with fewer top predators.