CALCULATING ENERGY FLOW

DEFINITIONS:

 

• Gross production:

  • The total amount of energy trapped in the organic matter produced by plants per area per time in kilojoules

  • Measured in (k) m^-2 yr^-1)

    • Kilojoules per meter squared per year

• Net production:

  • Gross production – energy lost through respiration

    • (kJ m^-2 yr ^-1)

• Biomass:

  • The dry weight of an organism, measured in grams per meter squared per year

    • (g m^-2 yr ^-1)

 

 

- Biomass is the dry weight of all the organisms at a certain tier of an ecosystem.

 

- The reason why we use dry weight is because organism include large amounts of water, therefore water needs to be removed in order to measure appropriately

 

 

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Constructing a pyramid of energy:

 

A pyramid of energy is a graphical model of energy flow in a community. The different levels of a pyramid represent different groups of organisms that might compose a food chain.

 

There are:

• Producers

• Primary consumers

• Secondary consumers

• Tertiary consumers

 

 

Constructing a pyramid of biomass:

 

- Similar to pyramids of energy, the higher trophic levels have a lower total biomass per unit area of ecosystem. Biomass is lost during respiration at every trophic level.

 

- When glucose is broken down for energy, it is converted into carbon dioxide glass and water.

 

- Carbon dioxide and water are excreted and the biomass of glucose is lost.

 

- As each level succeeds, the ecosystem loses more and more biomass. Though the energy per gram of food does NOT decrease, the total biomass of food is less at each trophic level.  

 

Constructing a pyramid of numbers:

 

- Has a similar shape to a pyramid of of energy

 

- Used to represent the population of a trophic level

 

- The wider the bar, the more of an organism there is

 

- Energy is lost to the surroundings as the trophic levels progress