环境生态学.docx
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环境生态学.docx
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环境生态学
Ecology
Ecologyisthestudyoftherelationshipbetweenorganismsandenvironment
TheTheoryofEvolutionbynaturalSelectionandthefourbasictenets
Themostappropriatebiologicalprogrammingforprevailingconditionswillleavethemostdescendants.
⏹
(1)Allindividualsproduceasmanyoffspringaspossible.
⏹
(2)Theyoungexhibitvariability,andsomearebettersuitedforsurvival.
⏹(3)Traitsareinheritedfromparents.
⏹(4)Someindividuallineagesaremoresuccessfulthanothers
Species
Agroupofpotentialoractuallyinterbreedingpopulationsthatarereproductivelyisolatedfromallotherpopulations.
Evolutionisthechangeinaspeciesovertime.Itshouldbethegeneticchangewithinalineage,ifthechangesissufficientlyprofoundanewspeciesisformed.
Whydidsofewphylasurvive?
Whydoesaspeciesgoextinct?
•Apopulationfailtoreproduce.Thefitnessfallsbelow1.
•eventsasdisease,competition,predation,habitatloss,climatechange
Forphyla
2mainreasons
•Competitionthatdrovetheleastadaptedphylaextinct.
•Environmentalcataclysm(环境大灾难)theimpactoflargemeteoritechangedtheEarth’climate–onlytheluckiestspeciescouldhavesurvived.(theformsthatsurvivedtheCambrianextinctioneventmayhavebeentheoneslivingindeeperoceanortheareaprotectedfromtheworsteffectsofclimatechange)
foraspecies,survivalorextinction?
?
•Bychance.Chancewouldhaveplayedasignificantroleindetermining.
Extinction&humans
•Extinctioneventspunctuatehistoryofevolution,asalreadymentioned,somearecausedbymeteoritesandsomebyclimatechange,butthemostrecentarecausedbyhumans.
DriftingContinentsandEvolution
•ContinentalDriftissignificanttoexplainsomebasicpatternsofsimilarityanddissimilarityoffloraandfaunaaroundtheworld.
•Allthecontinentswereclusteredtogetherasasinglelandmassuntil~200millionyearsago,thentheywerecollidingandseparatingintoseveralonesanddifferentshapes.
•thedriftingofcontinentsinducedvolcanicactivity,isolationofpopulations,andchange,eventsthatcanprovecriticalinthesurvival,extinctionandevolutionofspecies.
Biodiversity
•BiodiversityisthevarietyandvariabilityoflifeonEarth.
•ThisincludesalloftheplantsandanimalsthatliveandgrowontheEarth,allofthehabitatsthattheycallhome,andallofthenaturalprocessesofwhichtheyareapart.
•Alsoincludesvariationwithinaspeciescausedbygeneticvariation.
•Theearthsupportsanincrediblearrayofbiodiversity
WhatisSoGoodaboutBiodiversity?
•Thatbiodiversityshouldbemaintainedhasbecomeanarticleoffaithamongconservationists.
•Oneofthecommonanswershasbeenthatallnatureisinterwovenandthatifanypieceisremoveditwillstartachainreactionofcollapsethatwillultimatelydoomusall.(Betterbeexplainedbyfoodweb/chaininecosystems.Everyspeciesinfoodchainplayimportantroletoecosystem,bothaspreyandpredator,ittransportfoodandenergythroughfoodchain)
•Highbiodiversityensuresusasupplyofnewgeneticandpharmaceuticalmaterial.
Plantsandanimalsprovidepeoplewithfoodandmedicine.Fortypercentofallprescriptionswrittentodayarecomposedfromthenaturalcompoundsfoundindifferentspecies.Anestimated80,000edibleplantsarefoundintheworld,andoneineverythreemouthfulsofthefoodyouswallowispreparedfromplantspollinatedbywildinsectsandanimals.
•Theextinctionofeachadditionalspeciesresultsintheirreversiblelossofuniquegeneticmaterials,eachofwhichhaspotentialfordevelopmentofmedicinesandfoodsandassociatedenterprisesthatcreatejobs.
•Anyorganismcouldbevaluable,althoughtheydonotmakethecaserightnow.
•Anotherjustificationformaintainingbiodiversityisthatwecannotpredictwhichspecieswillbeneededforecologicalcontrol.(wewillneedsomespeciesmostofwhichareinsect,fungi,andbacteria,todealwiththeresistanceinpathogensandpestspeciesorexoticspecies.)
•Therefore,biodiversityisimportantasasourceofgeneticmaterialandnewdrugs,increasedecosystemstability,andforethicalandmoralreasons.Wearejustonespeciesamongmany,albeitaverypowerfulone,andthatitisourobligationtouseourcreativityandintellecttosustainlifeontheplanetandnotdestroyit.
Howbiologicallyuniqueisthearea?
•Todetermineifanareawasbiologicallyunique,thenumberofendemicplantspeciesisusedasanindicator.
•Becauseplantsaremuchbetterdescribedthaninsectsandmorediversethananimals.
•Furthermore,animalsaredependentonplants,animalsdiversityusuallymatchesplantsdiversity.
•Thepresenceofendemicspecieswerealsoincludedasameasureofbiologicalvalue.
Whydosethepatternexist?
(Biodiversityisnotspreadevenlyaroundtheplanetandthestrongestpatternisdecreasingspeciesdiversityfromtheequatortothepole.)
•Itlinkstotwoimportantenvironmentalfactors:
temperatureandprecipitation.
•Atthepoles,theshortgrowingseason,longnights,highwinds,andextremelylowtemperaturesproveinsurmountableobstaclestomostlifeforms.
Factorsaffectdiversity
•History--themostimportantreason
•Abioticcharacters
i.Sizeofhabitat
ii.Spatialpatchiness
iii.Harshnessofhabitat
iv.Predictabilityofchangeinthehabitat
v.Disturbanceinahabitat
vi.Isolationofahabitat
•Bioticfactors
vii.Ageofcommunitytype&Ageofparticularcommunity
viii.Primaryproductivity
ix.Communitystructure
x.Competition
xi.Predation
Islandeffect
•Largerislandcansupportmorespecies.
•S=cAz
Intermediatedisturbancehypothesis
Intermediatedisturbanceinahabitatmaymaintainhighbiodiversity.
Howtemperatureaffectorganismsandwhataretheadaptationsoforganisms?
•Mostspeciesperformbestinafairlynarrowrangeoftemperatures.--criticaltemperature
•Influencethephotosynthesisofvegetations.(e.g.potatozerophotosynthesisat40oC)
•Influencethephysiologicalreactionsoforganismsandacceleratesthegrowthrate.(e.g.Africans)
•Influencethedistributionoforganisms.(e.g.Malus(e.g.apple),pear,peach)
Adaptationsoforganismsmainlyinthefollowingaspects:
•Shapeandsize(e.g.theearoffox,thenoseofhuman)
•physiology(reducewater;increaseglucide,pigment,)
•behavior(hibernationandestivation)
Camelapproaches
Ecosystem
Theecosystemiscomposedofacommunityandthephysicalenvironmentitoccupies.
Componentsofecosystem
vAbioticenvironment
1.Soil,air,water,climate,andotherphysicalconditions(liketemperatureandpressure)
2.Inorganicelementsandcompounds(suchasC,N,CO2,O2,P,K,etc.)
3.Organicmatters(protein,carbohydratehumus)
vBioticfactors
1.producers–autotrophs
2.Consumers–heterotrophs
3.Decomposers
Functionsofproducers,consumersanddecomposers
•Producersarethebasisofnaturalecosystems.
•Consumerslinktoenergytransferandnutrientcyclinginecosystemsandregeneratesubstances.
•Decomposerspreventcommunitiesrapidlyrunningoutofthevariousinorganicsubstancesnecessaryforlife.
Typesofnaturalecosystems
vTerrestrialecosystems
1.WoodlandandForest
2.Grassland
3.Desert
4.TundraandAlpine
vAquaticecosystems
1.Freshwater
2.Saltwater
vWetland
Carboncycleandenvironmentalconcerns(globalwarmingandgreenhouseeffect)
nitrogencycleandenvironmentalconcerns
vNitrogenfixation
vAmmonification
vNitrification
vDenitrification
Environmentalconcerns
1.Water(surface-andground-)pollution
2.Greenhouseeffect(N2O)
3.Airpollution---Acidrain(NxO),Photochemicalsmog
4.Soilpollution(acidification)
5.O3depletion
Soil-Classificationofhorizons
vThetophorizon,aredarkincolor,almostblack,------litter,humus.
vLeachedlayers:
lightcoloredsandylayerfromwhichtheclayandmineralshavebeenleached.
vLayerofdeposition:
adarker,clay-richhorizon,oftenreddishordarkbrownbecauseofdepositionofmineralsaltsandproductsofhumus.
vParentmaterial:
rawweatheredmaterialfromtheunderlyingrockorfromsedimentarydeposits.
vBedrock:
Soilerosionbydeforestation(e.g.Ganges,in1982)
Reason?
=deforestinupper-streamareas
vTheerosionoftheAandOhorizonscangreatlyreducetheprimaryproductivityofanecosystem.
vWindisanimportanterosivefactor.
vTheMostimportantfactoriswater.
vWaterwashessoilfromtheland.
vVegetationsespeciallyforestsareveryimportanttopreventerosion.
vCanopyofbranchesoverheadintercepttherain,bondingrootsoftreesandsoilsabsorbtherainfalllikeasponge.
vTheforesthaslessenedthepossibleerosiveandfloodimpactofthestorm.
vNothingbreakstheimpactoftherainasitdirectlydrivesontotheexposedsoil.Soilbecomewaterloggedimmediately,andwashedawaywithsurfacerunoff.
vEvenworseinslopingarea,moresoilswilllosewithheavyrain.
Factorsinfluencethesoilformation
vParentmaterial
vTime
vClimate
vBioticprocesses
vTopography
Howorganismspassenergyupafoodchain?
•
•Thefirstlawofthermodynamics
–thelawofconservationofenergy
•Thesecondlawofthermodynamics
-thetransferofenergy
•Threerulesofenergyflow
1.Connexity(foodchain)
2.Onedirection/linear(onedirectionandonetime)
3.Attenuation(pyramid)
Factorsinfluencingprimaryproductivity
WaterandCO2availability,lengthofgrowingseason,temperature,lightlevels,oxygenandnutrientavailability
Whyaquaticcommunitiesareusuallylessproductivethanterrestrialones?
Theprocessoffoodtransferinheterotrophs
•Ingestion/intake(1s
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