1. PYRAMIDS
Pyramid diagrams give information about the organisms in a food chain:
numbers of organisms
biomass of organisms
energy stored in organisms
productivity of organisms
Taken from K:\General Education\IB\Science\Environmental ystems\ecosystems\pyramids.ppt
Taken from K:\General Education\IB\Science\Environmental systems\ecosystems\pyramids.ppt

2. PYRAMIDS OF BIOMASS
These show the total biomass of organisms at different trophic levels, which depends on:
the energy available at each trophic level
the standing crop at each trophic level
Biomass pyramid diagrams may be:
upright pyramids
inverted pyramids

3. How can a pyramid of biomass be inverted?
Pyramids of biomass measure standing crop at a particular moment in time
If you collected the cuttings from a garden lawn, mown twice a week during the summer, it would make a huge pile of biomass
But just after cutting, the biomass stored in the lawn would be quite small
Exchange your lawn mower for a rabbit and you can see how an inverted biomass pyramid could be produced
if you measured biomass over the whole summer for lawn and rabbit, the pyramid would look quite different

4. PYRAMIDS OF PRODUCTIVITY
These show productivity of organisms at different trophic levels, which depends on:
the energy available from the previous trophic level
the efficiency of the organisms
Productivity pyramid diagrams are always:
upright pyramids

5. Now try this: You will need graph paper, pencil, ruler
Draw a pyramid of numbers and a pyramid of biomass for each ecosystem
Remember to include the scale and units
Explain why pyramids of number may be upright or inverted
Are all the pyramids of biomass you have drawn upright?

6. Some extra data for the English Channel:
Draw a pyramid of biomass for this data
What type of pyramid is it?
Explain how this is possible, remembering the lawn and the rabbit.

7. Some extra data for a pool called Silver Springs in Florida