Pyramid of Biomass

 

A pyramid of biomass is a diagram that shows the total dry mass of living organisms at each trophic level (stage) in a food chain in an ecosystem.

 

           Eagle (0.1 kg)

         /\

        /  \

      Fox (1 kg)

     /\/\/\

   Rabbit (10 kg)

  \/\/\/\/\/\/\

Grass (1000 kg)

 

Why Biomass Decreases Further up the Pyramid

 

1. Only ~1% sunlight reaches the photosynthetic part of plants. Most is not absorbed or used.

2. ~10% energy transfer per level because not all of an organism is eaten by its predator

   • Energy lost in:  

     ◦ Respiration  

     ◦ Movement  

     ◦ Heat  

     ◦ Waste (urine, faeces)

 

Efficiency Calculation  

 

Efficiency (%) = (Biomass at higher level / Biomass at lower level) x 100

 

Example:  

Rabbit (10 kg) from Grass (1000 kg) → 1% efficiency