Ecological Pyramids

Energy Loss in Ecosystems I  Energy flow through an ecosystem is based on the laws of thermodynamics (physics)   First Law: Energy cannot be created or destroyed, it can only change forms   Second Law: When energy is being transformed, some of the energy is converted into an unusable form, and cannot be passed on.

Energy Loss in Ecosystems II   The energy transferred between trophic levels is inefficient.  on average, only 10% is passed from organisms in one trophic level to the next  90% of the energy is lost in the form of Heat, or used to fuel the activities of the organism that ingested it

Energy Consumption & Transfer

Ecological Pyramids: The Energy Pyramid energy distribution in a food chain is best illustrated using an pyramid the base of all energy pyramids is the producer level, and should be the largest section This is followed by the consumer levels

Energy Pyramids  Are based on the total chemical energy that flows through each level  measured in J or kJ  in all sustainable ecosystems, the energy available to every trophic level is less than the level before it. The pyramid is always upright!  Ideally, each consecutively higher level is approximately 90% smaller than the level directly below

Sample Energy Pyramids

Other Pyramids: Biomass  biomass = “total dry mass of a given population of organisms”  biomass combines Number of organisms with the size of the organisms  how much of a particular organism is there in an ecosystem?  usually, less biomass as you go up trophic levels  exceptions e.g. ocean ecosystem

Other Pyramids: Biomass

Pyramid of Numbers  a PYRAMID OF NUMBERS tells us how many individuals are present in an ecosystem  these can look very different from energy pyramids  many exceptions because of the physical size of members of the food chain

Example Pyramids of Numbers

The Energy Budget  in all food chains or food webs, energy available to maintain it inevitably runs out unless the original energy, sunlight is continuously fed into the system  There is a limit to how much energy is available in plant population, therefore there is limited available energy to all other levels above plants  the “ENERGY BUDGET” is the amount of energy changed from sun to plant that everyone has to share

  This budget means that in a balanced system there is always more energy at the lower trophic levels than at higher levels, and usually no more than 5 trophic levels exist in any food chain.