Human-Impact-on-Resources-and-Ecosystems人类对资源和生态系统的影响课件

HumanImpactonResourcesandEcosystems

Whatdidwedo?HumanspeciesexploitmineralresourcesandusenaturalecosystemTheyarealteredWesuccessbecausewehaveabilitytochangeoursurroundingsButHuman-Altereddoesnotequateto“Better”Whydoesecosystemmatter?Alllifeonearth,includinghumanlife,reliesonEcosystemservices–cleanair,cleanwater–renewableresources,etcForthefirsttimeinhistory,humanactionsareinfluencingecosystemsataglobalscale.–TheconsequencesforecosystemservicesarepoorlyunderstoodSome“ecosystemservices”•purificationofairandwater•mitigationofdroughtsandfloods•generationandpreservationofsoilsandtheirfertility•detoxificationanddecompositionofwastes•pollinationofcropsandnaturalvegetation•dispersalofseeds•cyclingandmovementofnutrients...•Howmuchcanwedegradeanecosystem,andstillreceivetheseservices?PollutionPollution-Anythingreleasedintotheenvironmentthataffectsanorganism’ssurvivalandreproduction.Human–peopleproduceinlargeenoughquantitiesthatitinterfereswithourhealthorwell-being.Olddays:smallpop.+simplemanner=dilutednaturalwaste,biodegradableNow:generatedfasterthanitcanbedegraded.Formsofpollution,fromhealthconcernstoannoyanceSeveralfactorsdeterminetheimpactofasocietyonnaturalresources.Impactofapop.=Pop.Size/AreaoccupiedxDegreeoftechnologicaldevelopmentPopulationsizePopulationdensityDegreeoftechnologicalDevelopment

alwaysunderestimated,purchasefromotherpart,effectindistantplaces.Throughouthistory,humanshavesoughttechnologicalsolutionstocombatecosystemdegradation.Short-termsolutionsEcosystemsModifiedbyHumanUseAgriculturalRangelandsForestsAquaticEcosystemsWildernessSpeciesExtinctionAgricultureEcosystem40%oftheworld’slandsurfacehasbeenconvertedtocroplandandpermanentpasture.Removeoriginalvegetation(whatisit?),substitutedbyexoticdomesticatedcropsandanimals.Pop.Increase,morelandornewtech?ForestsEcosystemsForestserviceClimatemodification…Protectorofwatershed…DeforestationForwoodorland,lostofhabitatornicheExposethesoiltoincreaseerosionTropicalforestdecrease0.6%peryear,temperateforestnosignificantchangeTropicaldeforestationThelossoftropicalrainforestcreateslocalenvironmentalproblemofenormousmagnitude,butfortheworld’speopletheimpacts,suchasclimatechange,arelong-term.

ForestmanagementClearcuttingvs.patch-workclearcuttingReforestationLumbercompany:fastgrowinghybridtreesplantation,onlyeconomicvalue.ExoticNodiversityRangelandEcosystemFromaridandsemiaridlandssupportgrassesorshrubsDomesticatedanimals,exoticspeciesSelectiveeating–plantsoeciesNativeanimalsOvergrazing-desertificationDesertification土壤荒漠化Overgrazingandmiss-farmingconvertaridandsemiaridareatodeserts.Thelossofvegetationincreaseerosionbywindandwater.

Extinction500millionto5-10million,98%extinctionNaturalselection,mostlytobeextinct:Lowpop.DensityFoundinsmallareaSpecializednicheLowreproductiverateHumanAcceleratedExtinctionFood–preyspeciesOrnament–animalskin,ivoryPest–tiger,wolfHabitatalterationQuestion?Whyworry?HumanImpactsonMarineSystems•fewsystemscannowbeconsidered'natural‘-allhavebeenmodified,eventhedeepoceans•humanactivityhaschangedmarinecommunitiesin5majorwaysglobalclimatechangeover-fishingofmarineorganismsinvasionsofexoticspecieschemicalpollutionandeutrophicationlossoralterationsofphysicalhabitatsOver-Fishing•fisheriesexploitationchangesmarineecosystemsmorerapidlyandoverlargescalesthanmostothereffects•leadstochangesin:distributionandabundanceofspeciesbodysize(sizeforreproduction)diversityoforganismsinsystemdynamicsoffoodwebs(lossofpredators)HabitatDamage•commercialfishinggearsareoftenverydestructivetohabitats•loststructureandfeaturescrucialforsupportingfisheryANDothercomponentsoftheecosystem•inmajorregionsoftheworldremoteimageryshowseverymetreofseabedasbeingtrawledmultipletimes•nowseeingdeclinesinrecruitmentofmanyspeciesthatneedhabitatasnurseryareaFig.p.95鱼类食物链污染Lipcancerofbullhead,insometributariesoftheGreatLakes,mayreach84%EcosystemImpacts•fisheriesoftentargettop-levelpredatorshighfoodandeconomicvalue(e.g.tuna)•thesespeciesoftenhaveenormousimpactontherestoftheecosystemso-called"KEYSTONE"species•historicalremovalfromover-fishingnowimplicatedinmajorecosystemcollapsesincluding;coralreefstropicalseagrassbedskelpforestsaquaculture?•SomeProblemstobeSolved

clearingofcoastalvegetationforfishfarms(e.g.mangroves)•pollutionfromfishfarmrunoffinputofdiseasesandnutrients•introductionofnewgeneticstockintowildpopulation•strongdependencyonwild-caughtfishinordertoprovidefoodforaquacultureCulturalEutrophication•nutrientslimitingtoprimaryproducers•excessiveloadingofnutrientsintowaterbodies=culturaleutrophicationhumanandanimalwasterunoffoffertilizersdepositionofnitrogenfromindustrialreleases,carexhaustsanddirectindustrialdischarges•mostcontrolattempts-pointsource•non-pointsourcereleasesimportantamountsNuisanceAlgalBlooms•increasedloadingofnutrientstoestuariesenhancesfrequencyandintensityofnuisancealgalblooms••increasedalgalproductiondoesnottranslatetohighsecondaryproductionplantsusuallytoxicorinediblenofish,consumealgaeFig.5.19mayinvolvetoxicforms,releasetoxicantmortalityofclamsandfishanoxicinbottomwaters,lowDO-'deadzones'onbottomofestuariesNaturalResourceStructuresandprocessesthathumancanusefortheirownpurposesbutnotcreate.Sunlight,metal,scenery,soil.Renewableresources:canbeformedorregeneratedbynaturalprocess.ie.Soil,forest;butnotinexhaustibleNonrenewableresources:fossilfuelandmineral.MineralResourceFormedmillionsofyearsagoQuestionBreak:Whatisit?Include…andCharacteristicinChinaUnevendistributionthroughouttheworldinternationalexchangeDisproportionateshareN.A.5.1%worldpopulation,30%consumptionCostsAssociatedWithResourceExploitationEconomic-monetarycostsnecessarytoexploittheresourceEnergy-energyexpendedexploitingtheresourceEnvironmental-environmentaleffectofresourceexploitation(oftendeferred)Question–