ecological pyramids: graphs which illustrate the trophic levels in a community
TRANSCRIPT
Most ecological pyramids are large at the base and narrow at
the top.
This is because every time that an organism is eaten by the next trophic level, some of the energy is lost as
heat. More Energy
Less Energy
Pyramid of Biomass:• Illustrates the amount of biomass in each trophic level
– Biomass weight is determined after dehydration
• Shows the amount of matter lost between trophic levels.
• Measured in Kg, grams or pounds
Pyramid of Energy:• Shows the energy available at each trophic level.
– The size of the blocks represents the proportion of productivity– Measured in Joules or Calories
Pyramid of Energy:• Most of the energy available to the community
is in the 1st trophic level.• Only 10-20% of the energy is available to the
next trophic level (≈ 90% lost)
How can more people be supported on Earth when there is a limited supply of resources?
Human Population Growth
It depends on what they are eating…