Comparing Energy Pyramids
Adapted from Pearson: Investigating Science 9
Purpose
To create and compare energy pyramids for two different ecosystems: a deciduous forest and a boreal
forest.
Materials
Calculator
Eight 2cm strips of coloured paper
Ruler
Glue
Scissors
Blank sheet of paper
Procedure
1. Copy the table below into your notebook, and write 30000 for Producers under the ‘Energy Present’
column. This table will be for deciduous forest.
2. Remember that only 10 percent of the energy in
Math Connection (#2)
producers is available to the primary consumers
To calculate 10% of a number, remember that:
that eat the producers. Calculate the amount of
10% = 10/100 = 0.1
energy available to the primary consumers.
So, 10% of a number is 0.1 x the number.
Record the value in your table.
Eg. 10% of 40,000 is 40,000 x 0.1 = 4,000
3. Calculate the amount of energy available to the
secondary consumers and tertiary consumers
and record the values in the table.
4. To create the energy pyramid, you will need to use a scale for your model so that 10mm equals 2000 kJ/m2.
Calculate the length, in millimeters, of paper strips
you will need to represent each level of the
Math Connection (#4)
pyramid. Record the values in the second column
To work out your scale, take the ‘Energy Present’,
of your table.
divide by 2000 kJ/m2, and multiply by 10mm. The
5. Cut a strip of paper to the correct length for the
result will be your scale distance.
producer level of the pyramid.
6. Repeat step 5 for the remaining levels of the pyramid. If you could not cut a narrow enough strip, use a
pencil to draw a 2-cm vertical line and indicate the width, in millimeters, that the line represents.
7. Glue the strips horizontally one above the other to form a pyramid. Make sure that the producer strip
forms the base of the pyramid and that the tertiary consumer strip forms the top.
8. Label each level of the pyramid. Give the pyramid a title.
9. Repeat steps 1 to 6 for the boreal forest. (For step 1, write 12 000 for Producers under the ‘Energy present’
column).
10. Glue the strips into the same page below the deciduous forest pyramid.
11. Label each level of the second pyramid and give the second pyramid a title.
Questions
1. Compared to the height of each pyramid, are the base levels relatively large or small? What does this mean
about the way energy flows through an ecosystem?
2. Which forest has more energy available to primary consumers? More energy available to tertiary
consumers?
3. Explain what happens to the energy that is not transferred at each level of the pyramid.
4. Write a statement comparing energy available in boreal and deciduous forests.
5. Suppose half of the deciduous forest was cut down and not replanted. Explain the consequences to the
consumers in the ecosystem. Would the consequences be the same if half the boreal forest was cut down?