Ecological PyramidsEcological Pyramids

Energy Loss in Ecosystems IEnergy Loss in Ecosystems I Energy flow through an ecosystem is Energy flow through an ecosystem is

based on the laws of thermodynamics based on the laws of thermodynamics (physics)(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 IIEnergy Loss in Ecosystems II

The energy transferred between trophic levels is inefficient.

on average, only 10% is passed from on average, only 10% is passed from organisms in one trophic level to the nextorganisms in one trophic level to the next

90% of the energy is lost in the form of 90% of the energy is lost in the form of Heat, or used to fuel the activities of the Heat, or used to fuel the activities of the organism that ingested itorganism that ingested it

Energy Consumption Energy Consumption & Transfer& Transfer

Ecological Pyramids: The Energy Ecological Pyramids: The Energy PyramidPyramid

energy distribution in a energy distribution in a food chain is best food chain is best illustrated using an illustrated using an pyramidpyramid

the base of all energy the base of all energy pyramids is the producer pyramids is the producer level, and should be the level, and should be the largest sectionlargest section

This is followed by the This is followed by the consumer levelsconsumer levels

Energy PyramidsEnergy Pyramids Are based on the total chemical energy that Are based on the total chemical energy that

flows through each levelflows through each level measured in J or kJmeasured in J or kJ in all in all sustainablesustainable ecosystems, the energy ecosystems, the energy

available to every trophic level is less than available to every trophic level is less than the level before it. The pyramid is always the level before it. The pyramid is always upright!upright!

Ideally, each consecutively higher level is Ideally, each consecutively higher level is approximately 90% smaller than the level approximately 90% smaller than the level directly below directly below

Sample Energy PyramidsSample Energy Pyramids

Other Pyramids: BiomassOther Pyramids: Biomass biomass = “total biomass = “total dry massdry mass of a given of a given

population of organisms” population of organisms” biomass combines Number of biomass combines Number of

organisms with the size of the organisms with the size of the organismsorganisms

how much of a particular organism is there how much of a particular organism is there in an ecosystem?in an ecosystem?

usuallyusually, less biomass as you go up trophic , less biomass as you go up trophic levelslevels

exceptionsexceptions e.g. ocean ecosystem e.g. ocean ecosystem

Other Pyramids: BiomassOther Pyramids: Biomass

Pyramid of NumbersPyramid of Numbers

a PYRAMID OF NUMBERS tells us how a PYRAMID OF NUMBERS tells us how many many individualsindividuals are present in an are present in an ecosystem ecosystem

these can look very different from these can look very different from energy pyramidsenergy pyramids

many exceptions because of the many exceptions because of the physical size of members of the food physical size of members of the food chainchain

Example Pyramids of NumbersExample Pyramids of Numbers

The Energy BudgetThe Energy Budget

in in allall food chains or food webs, energy available food chains or food webs, energy available to maintain it inevitably runs out unless the to maintain it inevitably runs out unless the original energy, sunlight is continuously fed into original energy, sunlight is continuously fed into the systemthe system

There is a limit to how much energy is available There is a limit to how much energy is available in plant population, therefore there is limited in plant population, therefore there is limited available energy to all other levels above plantsavailable energy to all other levels above plants

the “the “ENERGYENERGY BUDGETBUDGET” is the amount of ” is the amount of energy changed from sun to plant that everyone energy changed from sun to plant that everyone has to sharehas 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.