Env sci lecture5
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Transcript of Env sci lecture5
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
Goals Of EcologistsGoals Of Ecologists Understand how ecosystems functionUnderstand how ecosystems function Make connections: landscape ecologyMake connections: landscape ecology
Connections among ecosystemsConnections among ecosystems Great blue heronGreat blue heron
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 ThermodynamicsFirst Law of Thermodynamics Energy cannot be Energy cannot be
created or created or destroyeddestroyed
Energy can be Energy can be changed from one changed from one form to anotherform to another
Second Law of Second Law of ThermodynamicsThermodynamics
When energy is changed from one form When energy is changed from one form to another, some is degraded into heatto another, some is degraded into 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 waste Break down dead organisms and waste productsproducts
Examples?Examples?
Energy FlowEnergy Flow Energy passes from one organism to the Energy passes from one organism to the
nextnext 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
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 Cycle
OceanOcean 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 combine it Split atmospheric nitrogen and combine it
with hydrogenwith hydrogen
Nitrogen CycleNitrogen Cycle
Sulfur CycleSulfur Cycle
Underground sedimentary rocks and Underground sedimentary rocks and mineralsminerals
Erosion releases compounds to oceanErosion releases compounds to ocean VolcanoesVolcanoes Essential component of proteinsEssential component of proteins
Sulfur CycleSulfur 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 members Intimate relationship between members of at least 2 speciesof at least 2 species
Mutualism, commensalism, parasitismMutualism, commensalism, parasitism 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 species by Predation: consumption of one species by
anotheranother 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? This idea is being This idea is being challenged; why?challenged; why?
Case Study: Case Study: Global Climate ChangeGlobal Climate Change
Atmospheric COAtmospheric CO22 increased dramatically. increased dramatically. Why?Why?
10 warmest years have occurred since 199010 warmest years have occurred since 1990 2005 warmest2005 warmest 1998 second warmest1998 second warmest 2002 third warmest2002 third warmest
Earth’s temperatures may rise 1.8Earth’s temperatures may rise 1.8oo – 4.0 – 4.0oo C C (3.2(3.2o o – 7.2– 7.2oo F) by end of 21 F) by end of 21stst century century What could occur?What could occur?
Case Study: Case Study: Global Climate Change Global Climate Change
Kyoto Protocol – International climate change conference Kyoto Protocol – International climate change conference – Kyoto, Japan 1997– Kyoto, Japan 1997 Highly developed countries to cutHighly developed countries to cut COCO22 emissions ~ 5.2% by 2012 emissions ~ 5.2% by 2012
US Department of EnergyUS Department of Energy Automotive vehiclesAutomotive vehicles designed for better gasdesigned for better gas mileagemileage High efficiency windHigh efficiency wind turbinesturbines