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Chapter 3Chapter 3Ecosystems and EnergyEcosystems and Energy
Overview of Chapter 3Overview of Chapter 3
What is Ecology?What is Ecology? The Energy of LifeThe Energy of Life
Laws of ThermodynamicsLaws of Thermodynamics Photosynthesis and Cellular RespirationPhotosynthesis and Cellular Respiration
Flow of Energy Through EcosystemsFlow of Energy Through Ecosystems Producers, Consumers & DecomposersProducers, Consumers & Decomposers Ecological PyramidEcological Pyramid Ecosystem ProductivityEcosystem Productivity
EcologyEcology
EcologyEcology ““ecoeco”” house & house & ““logylogy”” study of study of The study of interactions among and The study of interactions among and
between organisms and their abiotic between organisms and their abiotic environmentenvironment
Biotic - living environmentBiotic - living environment Includes all organismsIncludes all organisms
Abiotic - non living or physical Abiotic - non living or physical environmentenvironment Includes living space, sunlight, soil, Includes living space, sunlight, soil,
precipitation, etc.precipitation, etc.
EcologyEcology
Ecologists Ecologists are are interested in interested in the levels of the levels of life above life above that of that of organismorganism
Ecology DefinitionsEcology Definitions SpeciesSpecies
A group of similar organisms whose members freely A group of similar organisms whose members freely interbreedinterbreed
PopulationPopulation A group of organisms of the same species that live A group of organisms of the same species that live
in the same area at the same timein the same area at the same time CommunityCommunity
All the populations of different species that live and All the populations of different species that live and interact in the same area at the same timeinteract in the same area at the same time
EcosystemEcosystem A community and its physical (abiotic) environmentA community and its physical (abiotic) environment
LandscapeLandscape Several interacting ecosystemsSeveral interacting ecosystems
EcologyEcology
Biosphere contains earthBiosphere contains earth’’s communities, s communities, ecosystems and landscapes, and includes:ecosystems and landscapes, and includes: AtmosphereAtmosphere - -
gaseous gaseous envelope envelope surrounding surrounding earthearth
HydrosphereHydrosphere - - earthearth’’s supply of s supply of waterwater
LithosphereLithosphere - soil - soil and rock of the and rock of the earthearth’’s crusts crust
EnergyEnergy
The ability or capacity to do workThe ability or capacity to do work Chemical, Thermal, Mechanical, Chemical, Thermal, Mechanical,
Nuclear, Electrical, and Radiant/Solar Nuclear, Electrical, and Radiant/Solar (below)(below)
EnergyEnergy
Energy exists as:Energy exists as: Potential energy Potential energy
(stored energy) (stored energy) Kinetic energy Kinetic energy
(energy of motion)(energy of motion) Potential energy is Potential energy is
converted to converted to kinetic energy as kinetic energy as arrow is releasedarrow is released
ThermodynamicsThermodynamics
Study of energy and its Study of energy and its transformationstransformations
System- the object being studiedSystem- the object being studied Closed System - Closed System - Does not Does not exchange energy exchange energy with surroundings with surroundings (rare in nature)(rare in nature)
Open System - Open System - exchanges energy exchanges energy with surroundingswith surroundings
Laws of ThermodynamicsLaws of Thermodynamics
First Law of ThermodynamicsFirst Law of Thermodynamics Energy cannot be created or destroyed; Energy cannot be created or destroyed;
it can change from one form to anotherit can change from one form to another
Second Law of ThermodynamicsSecond Law of Thermodynamics When energy is converted from one When energy is converted from one
form to another, some of it is degraded form to another, some of it is degraded to heatto heat
Heat is highly entropic (disorganized)Heat is highly entropic (disorganized)
PhotosynthesisPhotosynthesis
Biological process by which energy from Biological process by which energy from the sun (radiant energy) is transformed the sun (radiant energy) is transformed into chemical energy of sugar moleculesinto chemical energy of sugar molecules
6 CO6 CO2 2 + 12 H+ 12 H22O + radiant energyO + radiant energy
CC66HH1212OO66 + 6 H + 6 H22O + 6 OO + 6 O22
Cellular RespirationCellular Respiration
The process where the chemical The process where the chemical energy captured in photosynthesis is energy captured in photosynthesis is released within cells of plants and released within cells of plants and animalsanimals
This energy is then used for This energy is then used for biological workbiological work
CC66HH1212OO66 + 6 + 6 OO2 2 + 6 H+ 6 H22OO
6 CO6 CO22 + 12 H + 12 H22O + energyO + energy
Photosynthesis and Cellular Photosynthesis and Cellular RespirationRespiration
Energy FlowEnergy Flow
Passage of energy through an Passage of energy through an ecosystemecosystem ProducersProducers Primary consumersPrimary consumers Secondary consumersSecondary consumers DecomposersDecomposers
Food Chains - The Path of Energy Food Chains - The Path of Energy FlowFlow Energy from food passes from one Energy from food passes from one
organism to another based on their organism to another based on their Trophic LevelTrophic Level An organism’s position in a food chain An organism’s position in a food chain
determined by its feeding relationshipsdetermined by its feeding relationships First Trophic Level: ProducersFirst Trophic Level: Producers Second Trophic Level: Primary ConsumersSecond Trophic Level: Primary Consumers Third Trophic Level: Secondary Third Trophic Level: Secondary
ConsumersConsumers Decomposers are present at all trophic Decomposers are present at all trophic
levelslevels
Food WebFood Web
Ecological PyramidsEcological Pyramids
Graphically represent the relative Graphically represent the relative energy value of each trophic levelenergy value of each trophic level Important feature is that large amounts Important feature is that large amounts
of energy are lost between trophic levels of energy are lost between trophic levels to heatto heat
Three main typesThree main types Pyramid of numbersPyramid of numbers Pyramid of biomassPyramid of biomass Pyramid of energyPyramid of energy
Pyramid of NumbersPyramid of Numbers
Illustrates the number of organisms at Illustrates the number of organisms at each trophic leveleach trophic level Fewer organisms Fewer organisms
occupy each occupy each successive levelsuccessive level
Does not indicate:Does not indicate: biomass of biomass of
organisms at each organisms at each levellevel
amount of energy amount of energy transferred transferred between levelsbetween levels
Pyramid of BiomassPyramid of Biomass
Illustrates the total biomass at each Illustrates the total biomass at each successive trophic levelsuccessive trophic level Biomass: Biomass:
measure of the measure of the total amt of total amt of living materialliving material
Progressive Progressive reduction in reduction in biomass biomass through trophic through trophic levelslevels
Pyramid of EnergyPyramid of Energy
Illustrates how much energy is present Illustrates how much energy is present at each trophic level and how much is at each trophic level and how much is transferred to the next leveltransferred to the next level Most energy Most energy
dissipates dissipates between trophic between trophic levelslevels
Explains why Explains why there are so few there are so few trophic levelstrophic levels
Ecosystem ProductivityEcosystem Productivity
Gross Primary Productivity (GPP)Gross Primary Productivity (GPP) Total amount of energy that plants capture Total amount of energy that plants capture
and assimilate in a given period of timeand assimilate in a given period of time Net Primary Productivity (NPP)Net Primary Productivity (NPP)
Plant growth per unit area per timePlant growth per unit area per time Represents the rate at which organic Represents the rate at which organic
material is actually incorporated into the material is actually incorporated into the plant tissue for growthplant tissue for growth
GPP – cellular respiration = NPPGPP – cellular respiration = NPP Only NPP is available as food to organismsOnly NPP is available as food to organisms
Variation in NPP by Variation in NPP by EcosystemEcosystem
Human Impact on NPPHuman Impact on NPP
Humans represent 0.5% of land-Humans represent 0.5% of land-based biomass, but use 32% of land-based biomass, but use 32% of land-based NPP!based NPP! This may contribute to loss of species This may contribute to loss of species
(extinction)(extinction) This represents a threat to planetThis represents a threat to planet’’s s
ability to support both human and ability to support both human and non-human inhabitantsnon-human inhabitants