Food and energy Food and energy cyclescyclesCP Biology - ECOLOGYCP Biology - ECOLOGY

Energy flowEnergy flow

An ecosystems energy budget is determined An ecosystems energy budget is determined by the amount of photosynthetic activity of the by the amount of photosynthetic activity of the producersproducers

Producers use light energy to synthesize Producers use light energy to synthesize organic molecules which are then used to organic molecules which are then used to make ATP in cellular respirationmake ATP in cellular respiration

Consumers obtain energy from organic Consumers obtain energy from organic molecules produced in lower trophic levelsmolecules produced in lower trophic levels

Consumers use food energy for:Consumers use food energy for: Cell respirationCell respiration Maintaining life processes (homeostasis, Maintaining life processes (homeostasis,

growth, development, etc)growth, development, etc) Some is lost in waste products and as heatSome is lost in waste products and as heat

Energy has to constantly be added to Energy has to constantly be added to and ecosystemand ecosystem

An overview of ecosystem dynamicsAn overview of ecosystem dynamics

Organismal ecologyOrganismal ecology

Organisms can be put into 1 of 2 groups based on the Organisms can be put into 1 of 2 groups based on the costs and benefits of maintaining homeostasiscosts and benefits of maintaining homeostasis Regulators expend energy in response to changing Regulators expend energy in response to changing

environmental conditions; the energy costs cannot exceed the environmental conditions; the energy costs cannot exceed the benefits of regulating their internal environmentbenefits of regulating their internal environment

Conformers allow their internal conditions to vary with the Conformers allow their internal conditions to vary with the external environmentexternal environment

The principle of allocation says that organisms have a limited The principle of allocation says that organisms have a limited amount of energy to spend on all life functions; the energy amount of energy to spend on all life functions; the energy spent on one canspent on one can’’t be spent on the others.t be spent on the others.

Regulators and conformersRegulators and conformers

The relationship between body temperature and ambient (environmental) The relationship between body temperature and ambient (environmental) temperature in an ectotherm and an endothermtemperature in an ectotherm and an endotherm

Primary productivityPrimary productivity

Gross primary productivity (GPP): The Gross primary productivity (GPP): The amount of light energy converted to amount of light energy converted to chemical energy by autotrophs in an chemical energy by autotrophs in an ecosystem; some is stored by plant, ecosystem; some is stored by plant, some is used for life processessome is used for life processes

Net primary productivity (NPP): the Net primary productivity (NPP): the amount of chemical energy available to amount of chemical energy available to consumers; also called biomassconsumers; also called biomass

Figure 54.3 Primary production of different ecosystemsFigure 54.3 Primary production of different ecosystems

Figure 54.4 Regional annual net primary production for EarthFigure 54.4 Regional annual net primary production for Earth

Secondary productivitySecondary productivity

Rate at which consumers convert the Rate at which consumers convert the chemical energy in the food they eat to chemical energy in the food they eat to their own biomasstheir own biomass Consumers use energy for life functions but Consumers use energy for life functions but

cannot completely digest the food so only cannot completely digest the food so only about 10% of the energy consumed is about 10% of the energy consumed is available to the next trophic levelavailable to the next trophic level

Pictured in a pyramidPictured in a pyramid

Figure 54.10 Energy partitioning within a link of the food chainFigure 54.10 Energy partitioning within a link of the food chain

Types of pyramidsTypes of pyramids

Pyramid of productivity (at trophic levels)Pyramid of productivity (at trophic levels) Biomass pyramidBiomass pyramid Pyramid of numbers (individuals)Pyramid of numbers (individuals) All are similar in that the bases are wide All are similar in that the bases are wide

(lots of producers) and narrow greatly at (lots of producers) and narrow greatly at the top (few top level consumers) and the top (few top level consumers) and only have 3-5 trophic levelsonly have 3-5 trophic levels

An idealized pyramid of net productionAn idealized pyramid of net production

A pyramid of numbersA pyramid of numbers

Biogeochemical cyclesBiogeochemical cycles

Global recycling: gaseous elements are Global recycling: gaseous elements are recycled in the atmosphere (oxygen, recycled in the atmosphere (oxygen, nitrogen, carbon, sulfur)nitrogen, carbon, sulfur)

Local recycling: elements that are solid Local recycling: elements that are solid are recycled in the soil (phosphorous, are recycled in the soil (phosphorous, potassium, calcium, trace elements)potassium, calcium, trace elements)

Matter is recycled, energy is notMatter is recycled, energy is not

A general model of nutrient cyclingA general model of nutrient cycling

U.S. map profiling pH averages for precipitation in 1999U.S. map profiling pH averages for precipitation in 1999

Figure 54.25 Biological magnification of DDT in a food chainFigure 54.25 Biological magnification of DDT in a food chain