Download - Chapter 5 How Ecosystems Work
Chapter 5Chapter 5How Ecosystems WorkHow Ecosystems Work
Lake VictoriaLake Victoria Freshwater lake in AfricaFreshwater lake in Africa Formerly home to ≈ 400 species of cichlidsFormerly home to ≈ 400 species of cichlids 1960: Nile perch 1960: Nile perch
introducedintroduced 1990: water hyacinth 1990: water hyacinth
invadedinvaded Today, ecological Today, ecological
imbalance; why?imbalance; why?
What Is Ecology?What Is Ecology? Literally study of one’s “house”Literally study of one’s “house” InteractionsInteractions Two componentsTwo components
BioticBiotic AbioticAbiotic
Broadest biological field of studyBroadest biological field of study
Ecological OrganizationEcological Organization
OrganismOrganism PopulationPopulation CommunityCommunity EcosystemEcosystem LandscapeLandscape BiosphereBiosphere
Positive and Negative Positive and Negative Feedback LoopsFeedback Loops
Feedback LoopFeedback Loop circular processcircular process
Positive Feedback LoopPositive Feedback Loop change becomes more change becomes more
pronouncedpronounced Negative Feedback LoopNegative Feedback Loop
change is reduced or inhibitedchange is reduced or inhibited
Landscape EcologyLandscape Ecology Studies the connections Studies the connections
among ecosystemsamong ecosystems Ecosystem engineers Ecosystem engineers
Organisms that create Organisms that create or modify habitator modify habitat
How are grizzly bears How are grizzly bears ecosystem engineers?ecosystem engineers?
Goals Of EcologistsGoals Of Ecologists Understand how ecosystems functionUnderstand how ecosystems function Make connections: landscape ecologyMake connections: landscape ecology
Connections among ecosystemsConnections among ecosystems Grizzly BearsGrizzly Bears
EnergyEnergy Capacity or ability to do workCapacity or ability to do work Flows through ecosystemsFlows through ecosystems Why do organisms need energy?Why do organisms need energy? Different kindsDifferent kinds
Potential energyPotential energy Kinetic energyKinetic energy
First Law of First Law of ThermodynamicsThermodynamics
Energy cannot Energy cannot be created or be created or destroyeddestroyed
Energy can be Energy can be changed from changed from one form to one form to anotheranother
Second Law of Second Law of ThermodynamicsThermodynamics
When energy is changed from one When energy is changed from one form to another, some is degraded form to another, some is degraded into heatinto heat
Heat is a less usable form of energyHeat is a less usable form of energy Increases entropy in the universeIncreases entropy in the universe
Ecosystem CompositionEcosystem Composition
ProducersProducers ConsumersConsumers DecomposersDecomposers
ProducersProducers
Make their own foodMake their own food PhotosynthesisPhotosynthesis Examples?Examples?
6CO6CO22 + 6H + 6H22O + ------> CO + ------> C66HH1212OO66 + 6O + 6O22
Light energy
Light energy
ConsumersConsumers
Feed on other thingsFeed on other things HerbivoresHerbivores CarnivoresCarnivores OmnivoresOmnivores DetrivoresDetrivores
DecomposersDecomposers
Break down dead organisms and Break down dead organisms and waste productswaste products
Examples?Examples?
Energy FlowEnergy Flow Energy passes from one organism to Energy passes from one organism to
the nextthe next Trophic level: each step in this flow of Trophic level: each step in this flow of
energyenergy Food chain: straight pathFood chain: straight path Food webFood web
Interconnected food chainsInterconnected food chains More realistic than food chain; why?More realistic than food chain; why?
Food ChainFood Chain
Biological ProductionBiological Production Net Primary Production: amount of Net Primary Production: amount of
plant mass generated by plant mass generated by photosynthesis and that remains after photosynthesis and that remains after cellular respirationcellular respiration
Biomass: total amount of organic Biomass: total amount of organic mattermatter
NPP is measured by tracking the NPP is measured by tracking the changes in biomass over timechanges in biomass over time
(NPP = B2 –B1)(NPP = B2 –B1)
Food Food WebWeb
Biogeochemical CyclesBiogeochemical Cycles
Matter cycles through ecosystemsMatter cycles through ecosystems Five cyclesFive cycles
CarbonCarbon Hydrologic (water)Hydrologic (water) NitrogenNitrogen SulfurSulfur PhosphorusPhosphorus
Carbon CycleCarbon Cycle
Essential component for lifeEssential component for life Gas (COGas (CO22) in atmosphere) in atmosphere Several forms in oceanSeveral forms in ocean Can take a long time—think fossil fuelsCan take a long time—think fossil fuels
COCO22 SugarSugar COCO22
PhotosynthesisPhotosynthesis Cellular respirationCellular respiration
Carbon CycleCarbon Cycle
Hydrologic CycleHydrologic CycleOceanOcean AtmosphereAtmosphere LandLand OceanOcean
Nitrogen CycleNitrogen Cycle Proteins, DNAProteins, DNA Atmosphere is 78% NAtmosphere is 78% N22
Five stepsFive steps Nitrogen fixationNitrogen fixation NitrificationNitrification AssimilationAssimilation AmmonificationAmmonification DenitrificationDenitrification
Nitrogen FixationNitrogen Fixation Specialized bacteriaSpecialized bacteria Split atmospheric nitrogen and Split atmospheric nitrogen and
combine it with hydrogencombine it with hydrogen
Nitrogen CycleNitrogen Cycle
Phosphorus CyclePhosphorus Cycle
No atmospheric componentNo atmospheric component Phosphates used in DNA and ATP Phosphates used in DNA and ATP
(chemical energy)(chemical energy) Phosphates move through the food chainPhosphates move through the food chain
LandLand OrganismOrganism LandLandOrganismOrganism
Phosphorus CyclePhosphorus Cycle
Ecological NicheEcological Niche Everything about an organismEverything about an organism
AdaptationsAdaptations Use of resourcesUse of resources LifestyleLifestyle HabitatHabitat
Ecological NicheEcological Niche
Two species cannot occupy the same Two species cannot occupy the same niche: why?niche: why?
Resource partitioningResource partitioning Reduces niche overlapReduces niche overlap Reduces competitionReduces competition
Resource Partitioning At Work!Resource Partitioning At Work!
Species InteractionsSpecies Interactions No species lives in complete isolationNo species lives in complete isolation SymbiosisSymbiosis
Intimate relationship between Intimate relationship between members of at least 2 speciesmembers of at least 2 species
Mutualism, commensalism, Mutualism, commensalism, parasitismparasitism
Result of coevolutionResult of coevolution Other interactionsOther interactions
Predation, competitionPredation, competition
MutualismMutualism Both species benefitBoth species benefit
CommensalismCommensalism One species benefits, other not affected One species benefits, other not affected
ParasitismParasitism Parasite benefits, host is “harmed”Parasite benefits, host is “harmed” Ectoparasites & endoparasitesEctoparasites & endoparasites
Species InteractionsSpecies Interactions Predation: consumption of one Predation: consumption of one
species by anotherspecies by another Coevolution: “arms race”Coevolution: “arms race”
Avoiding PredatorsAvoiding Predators Mechanical defensesMechanical defenses Social groupsSocial groups CamouflageCamouflage Protective chemicalsProtective chemicals
Species InteractionsSpecies Interactions Competition: two or more organisms Competition: two or more organisms
attempting to use the same resourceattempting to use the same resource Intraspecific vs. interspecificIntraspecific vs. interspecific
Keystone SpeciesKeystone Species Crucial to maintenance of an ecosystemCrucial to maintenance of an ecosystem Loss affects many other Loss affects many other
speciesspecies Examples?Examples? What are the differences What are the differences
between a keystone, between a keystone,
umbrella or flagship umbrella or flagship
species?species?
Adaptive EcosystemAdaptive EcosystemManagementManagement
Ecosystem Management: meeting the goals or Ecosystem Management: meeting the goals or objectives of the biotic community and their associated objectives of the biotic community and their associated abiotic componentsabiotic components
Adaptive Ecosystem Management:Adaptive Ecosystem Management: developed by C.S. Holling and Carl J. Walters, developed by C.S. Holling and Carl J. Walters,
University of B.C., 1970University of B.C., 1970 acknowledges the uncertainty and the need for acknowledges the uncertainty and the need for
managers to learn while they managemanagers to learn while they manage passive and activepassive and active
Eco Canada Career FocusEco Canada Career Focus
Consider a career Consider a career as an ecologistas an ecologist
Ecologists study Ecologists study the relationships the relationships between living between living things and their things and their environmentsenvironments
Case Study: Human Case Study: Human Appropriation of Net Primary Appropriation of Net Primary
Productivity (HANPP)Productivity (HANPP) HANPP : indicator of are of land an the HANPP : indicator of are of land an the
amount of biomass consumed by amount of biomass consumed by humanshumans
Valuable indicator of “human domination Valuable indicator of “human domination of ecosystems” on a global scaleof ecosystems” on a global scale
Many countries are consuming an excess Many countries are consuming an excess of 100% of locally available NPPof 100% of locally available NPP
Case Study: Human Case Study: Human Appropriation of Net Primary Appropriation of Net Primary
Productivity (HANPP)Productivity (HANPP)