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首页 《science》杂志一期土壤专题.pdf

《science》杂志一期土壤专题.pdf

《science》杂志一期土壤专题.pdf

上传者: wfsunsdu 2009-12-30 评分 5 0 193 26 878 暂无简介 简介 举报

简介:本文档为《《science》杂志一期土壤专题pdf》,可适用于工程科技领域,主题内容包含wwwsciencemagorgSCIENCEVOLJUNESOILSTHEFINALFRONTIERSPECIALSECTIONInmanyway符等。

wwwsciencemagorgSCIENCEVOLJUNESOILSTHEFINALFRONTIERSPECIALSECTIONInmanywaysthegroundbeneathourfeetisasalienasadistantplanetTheprocessesoccurringinthetopfewcentimetersofEarth’ssurfacearethebasisofalllifeondryland,buttheopacityofsoilhasseverelylimitedourunderstandingofhowitfunctionsAscreaturesoftheaerialworld,wehaveadecidedlydistortedviewofthisnurturingunderworldForecologists,soilfascinatesandflummoxesinequalmeasureThetechniquesandapproachesofmanybranchesofabovegroundecologydon’ttranslatewelltothesoilenvironmentHowever,perspectivesarebeginningtochange,asthearticlesinthisspecialissueshowInterestinsoilisbooming,spurredinpartbytechnicaladvancesofthepastdecadeMolecularphylogenetics,forexample,isrevealingtheextentofthediversityofsoilmicroorganismsandhowpatternsofdiversitychangeovertimeAdvancesinunderstandingofthemutualinfluencesoftheundergroundandabovegroundcomponentsofecosystemsarereviewedbyWardleetal(p)Ecologistshavetraditionallyportrayedtheinhabitantsofsoilasablackboxlabeled“decomposers”essentially,asingletrophiclevelthroughwhichallabovegroundmaterial,withitsmultipletrophiclevels,isultimatelyrecycledDiggingdeeper,itturnsoutthatthesoilfoodwebiseverybitascomplexastheabovegroundweb,withintricateconnectionstoitsaerialcounterpartInthesubterraneanworld,ecologyiswritsmallThespatial,chemical,andbiologicalheterogeneitywithinafewcubiccentimetersofsoilrivalsthatofahectareofforestorcoralreefYoungandCrawford(p)describesomeofthenewtechniquesfordocumentingandvisualizingthemicroscopiccomplexityunderfootInaNewsstory,Pennisi(p)providesastageforoneunsungsubsurfaceduet:soilfungiandplantrootsButEarth’sskinisfragileindeedAmap(p)vividlyillustratestheextentofsoildegradationandlossacrosstheglobe,andinaNewsstory,Proffitt(p)previewsanefforttoascertaintheextenttowhichcontaminantshaveinfiltratedsoilsinNorthAmericaKaiser(News,p)surveyssoildegradationandassesseswhatitbodesforcropyields,andLal,inaViewpoint(p),outlinesthemanagementprotocolsthatareneededtoenhancethesustainabilityofagriculturalsoilsandtheabilityofsoiltosequestercarbonTheprospectofmassiveamountsofcarbonbeingliberatedwiththemeltingoffrozensoilsintheHighArcticisexploredinaNewsstorybyStokstad(p)Humanattitudestowardsoil,astowardtherestoftheenvironment,rangefromreverenttocavalierThehistoricaldevelopmentofourvariedrelationshipwithsoilischartedinaViewpointbyMcNeillandWiniwarter(p),andasurveyofthesoilfertilityofanancientagroecosystemisgiveninaReportbyVitouseketal(p)Delvingdeeperintothehiddenworldofsoilswillsurelyrevealnewconnectionstoourfamiliarenvironsandmakesubterraneanaseemfarlessofanalienexperience–ANDREWSUGDEN,RICHARDSTONE,ANDCAROLINEASHEcologyintheUnderworldINTRODUCTIONCONTENTSNEWSSoilandTroubleWoundingEarth’sFragileSkinFromAlaskatoYucatan,aLongAwaitedSoilSurveyTakesShapeDefrostingtheCarbonFreezeroftheNorthTheSecretLifeofFungiVIEWPOINTSSoilCarbonSequestrationImpactsonGlobalClimateChangeandFoodSecurityRLalBreakingtheSod:Humankind,History,andSoilJRMcNeillandVWiniwarterREVIEWSEcologicalLinkagesBetweenAbovegroundandBelowgroundBiotaDAWardleetalInteractionsandSelfOrganizationintheSoilMicrobeComplexIMYoungandJWCrawfordSeealsoReportonpagePAGECREDIT:STEFANOPAGIOLASovieteraintensivetillagehasleftoftopsoilacrossCentralandEasternEuropetoodenselypackedtoallowsufficientwaterandnutrientstoreachplantrootsCENTRALEASTERNEUROPEcompactionDecadesofwatererosionontilledfieldshasdegradedsoilacrosstheMidwestandGreatPlains,althoughnotillagriculturehasrecentlystemmedlossesUNITEDSTATESerosionCoveringofsoilswithbuildingsandroadshasputbeyonduselargeswathsofprimesoilinEuropeancitiesWESTERNEUROPEsealingSlashandburnagricultureintheAmazonexposespoortropicalsoilsthatcansustaincropsforonlyafewyearsbeforenutrientswashawayAMAZONerosionPHYSICALDEGRADATIONCHEMICALDEGRADATIONHighandveryhighlevelsofsoildegradationperGlobalAssessmentofSoilDegradation(GLASOD)HighlyerodablebywindorwaterFewconstraintsClimateConstraintsHightemperaturesSeasonalcoldSeasonallyexcesswaterSeasonaldrynessContinuouscoldContinuousdrynessWHENPEOPLEINTENSIVELYTILLFIELDSandclearcutforests,theycandamageordestroytopsoilthattookcenturiestoaccumulateJusthowvulnerablesoilsaredependsonunderlyingconditionsMismanagedsoilsinwindsweptlandscaneasilyturnintodesert,forexample,andsalinesoilscanbecomesaltencrustedwastelandsThismapshowsthemainbarrierstoproductivefarming,alongwitherosionrisk,derivedfromclimaticandsoilconditionsOverlaidascrosshatchingareregionsreportedtobehighlyorveryhighlydegradedaccordingtoaglobalsurveyofsoilexpertspublishedinThehotspotsillustrateexamplesoftheworstsoildegradation,fromthemostcommonphysicaltypewatererosiontochemicalforms,suchasthatcausedbypollutionfromindustrialchemicalsandwarAninteractiveversionofthismapappearsonlineatwwwsciencemagorgcgicontentsummarySoilandTroubleGETTYIMAGESJOHNKIMBLEUSDASCHEUFLERCOLLECTIONCORBISMARTINJONESECOSCENECORBISSOURCES:AdaptedfromMajorLandResourceConstraintsmapcreatedAprilbyPReichandHEswaranofUSDANRCSSoilSurveyDivision,WorldSoilResources,Washington,DC,fromWSRSoilClimateMapandFAOSoilMapoftheWorld,GLASODdata(LROldemanetal,)providedbyKSebastian,IFPRIDataoncompactioninEuropefromSOVEURISRIC()billiontonsofsoilperyearwashintotheYellowRiverfromChina’sLoessPlateau,whichhasthehighestratesofwatererosionintheworldCHINAerosionTheexpansionofdesertsduetofarmingandgrazingstokesthecountry’sfamousduststormsCHINAdesertificationKAZAKHSTANUZBEKISTANpollution,desertificationShrinkageoftheAralSea,duetodiversionofwaterfromitstributaries,hasexposedaseabedlacedwithfertilizersandpesticidesThetainteddustispickedupbythewindandpoisonsfarmlandDuringthefirstGulfWar,milliontonsofKuwaitisoilweredrenchedwithoilExpertsfearthatsoilsinIraqarebeingdamagedbyfuelandotherchemicalsspilledduringthecurrentconflictIRAQpollutionFieldsrarelyleftfallowandthescavengingofvegetationanddunghaveconspiredtominethesoilofnutrientsSUBSAHARANAFRICAnutrientdepletionOvergrazinganddeforestationhavespurredwidespreadsoilerosioninthelowerHimalayaMountains,wherenaturalratesarealreadyhighbecauseofmonsoonalrainsRemovalofvegetationhasallowedthewatertabletoliftunderlyingsalts,leadingtobarrenlandscapessuchasthisoneinWesternAustralia’swheatbeltAUSTRALIAsalinizationHIMALAYASerosionHighphosphorus,nitrogen,andorganicretentionHighorganicmatterSalinityalkalinityLoworganicmatterHighanionexchangecapacityHighaluminumCalcareous,gypseousconditionLownutrientholdingcapacityLowmoistureandnutrientstatusChemicalConstraintsPhysicalConstraintsHighshrinkswellpotentialMinorrootrestrictinglayerLowstructuralstabilityImpededdrainageLowwaterholdingcapacityShallowsoilsNOTE:Acidsulfatecondition(oftotalmaparea)andsteeplands(obscuredbyerosionrisk)arenotshownCSIROLANDWATERRICKYWONGVINCESTREANOCORBISAFPGETTYIMAGESCHIHUAHUANGMUTSUMIYSTONEWILDCOUNTRYCORBISJUNEVOLSCIENCEwwwsciencemagorgTherebelinsurgencythattoppledHaiti’sgovernmentearlierthisyearwas,onthesurface,simplythelatestturninabloodycycleofrepressionandreactionButdeeperdown,theuprisingexposedarootcauseofthecountry’smisery:someofthemostdenudedlandontheplanetOnlyoftheoncelushlyforestedterrainstillhastreecover,anduptoonethird,some,hectares,haslostsomuchtopsoilthatitisnolongerarable,orbarelysoTodaythelandscapeiscrisscrossedbygullyscarred,deforestedhillsand“rockswherethereusedtobedirt,”saysAndyWhite,aneconomistatForestTrends,anonprofitorganizationinWashington,DCErosionhasbroughttheCaribbeancountry’sagriculturetoitsknees,hesays,andthatinturn“hasdrivenruralpoverty,”impellingdesperateHaitianstowardcityslumswhereunrestcontinuestosimmerThetremendoushemorrhagingoffertilesoilmakesHaitioneoftheglobalhotspotsfordegradation,asillustratedontheprecedingpagesFordecadessoilscientistshavedeploredthelossoflandtoerosion,nutrientdepletion,salinization,andotherinsultsButpolicymakershavebeenslowtorespondOnereasonisthatdirewarningsinthesthatsoilerosionwoulddoomtheworldtochronicfoodshortageshavefailedtopanoutButinthepastfewyears,newstudieshaveyieldedbetterdatalinkingsoildegradationtoaslumpinthegrowthofglobalcropyields,unitingduelingcampsAfteryearsof“peckingawayatthisproblem,”soilscientists,geographers,andeconomists“arecomingtowardthemiddle,”saysKeithWiebe,aresourceeconomistattheUSDepartmentofAgriculture(USDA)Thebottomline:“Asaglobalproblem,soillossisnotlikelytobeamajorconstrainttofoodsecurity,”saysStanleyWood,aseniorscientistattheInternationalFoodPolicyResearchInstituteinWashington,DCButasHaitiansknowalltoowell,degradationcanbeasevereanddestabilizingthreatinplaceswherefarmersaretoopoortocurborovercomethedamageMoreover,globalwarmingisexpectedtoexacerbateregionalcrisesAsthegroundheatsup,organicmatterdecomposesmorereadily,reducingsoilfertilityand,assertsDukeUniversityecologistWilliamSchlesinger,releasingcarbondioxideintotheairtofuelwarmingDesertsarealsoexpectedtoexpandanderosionworsenifviolentstormsoccurmorefrequentlyButthere’saflipside,sayssoilscientistRattanLalofOhioStateUniversity,Columbus:“Wecandosomethingaboutit”bymanagingsoilstostemerosionandretainmorecarbonAlitanyoflossThefirstrealeyeopenertotheconsequencesofsoilabusecameduringAmerica’sGreatDepressioninthesForyears,“blackblizzards”oftopsoilwouldintermittentlyblotoutthesunintheGreatPlains,buryingfarmsindustanddrivingmanyfamiliesfromtheirlandTheDustBowlwastriggeredbyacombinationofdroughtandshoddyagriculturalpractices:Farmerswouldplowgrasslands,leavinglittlevegetationtoholdontowaterandtopsoilwhenfieldslayfallowThecrisisledtothecreationinofUSDA’sSoilConservationService,whichdevelopednewpracticestocurberosionTheseincludedusingplowingmethodsthatfollowtheland’scontoursacrossslopes,forexampleandgrowingcovercropstoretainsoilbetweenplantingseasonsThissoilrevolutionofsortspromptedscientiststostartdelvingmoredeeplyintothemechanismsofdegradationOnetypeispurelyphysical,mainlytheresultofwindandwatererosionOnChina’swindsweptLoessPlateau,northwestoftheYellowRiverBasin,soiliscarriedawayfasterthananywhereelseintheworld:Eachyeartheplateaulosesbilliontonsofloess,apowderysoildepositedovermillenniabywindstormsLikewise,mountainrangesarepronetoerosioncausedbyheavyrainsthatstriptopsoilfromsteepslopesInthelowerHimalayas,forexample,“thelandhaslostitscapacityforanyproductivepurposes,”saysecologistPRRamakrishnanofJawaharlalNehruUniversityinNewDelhiInamorevampyricformofdegradation,sowingcropswithoutfertilizersseasonafterseasondrainsthesoilofitslifeblood:nutrientsSoilsinsubSaharanAfricaarerapidlylosingfertilitybecausefarmersgenerallycan’taffordfertilizersandaresalvagingpostharveststubbleandevenlivestockdungforfuelBeforethes,saysUSDAsoilscientistHariEswaran,AfricanfarmersroutinelywouldleavelessproductivefieldsfallowforagenerationThenthepopulationexploded,andnow“everypieceoflandistakenup,”EswaransaysAnotherformofchemicaldegradationoccurswhenpoorirrigationpracticessaturatelandwithsaltanacutewoeintheMiddleEastandIndiaAndinAustralia,theremovalofwaterhoardingnativeplantshasledtorisingwatertablesthatsuffusetopsoilwithsalt,sayshydrologistMirkoStauffacheroftheCommonwealthScientificandIndustrialResearchOrganisationTheagencyestimatesthatofAustralia’sagriculturallandsarenowaffected,afigureexpectedtotriplebyInsomeareas,Stauffachersays,“nothingcangrow”Desertification,meanwhile,plaguestheSahelinAfricaaswellasKazakhstan,Uzbekistan,andnorthernChina,wheredesertisgrowingbysquarekilometersayearanarealargerthanRhodeIslandfuelingthemassiveduststormsthatchokeCREDIT:STEFANOPAGIOLASOILSTHEFINALFRONTIERSPECIALSECTIONNEWSWoundingEarth’sFragileSkinSoildegradationinallitsnefariousformsisnotapreludetomassstarvation,asanalystsoncefearedNevertheless,itiserodingcropyieldsandcontributingtomalnourishmentinmanycornersoftheglobeSorespotErosionfromtimbercutting,overgrazing,andotherhumanactivitieshasleftuptoonethirdofHaiti’slandirreversiblydamagedBeijingandothercitiesNewfarmsencroachingongrasslands,abettedbywinderosion,aredrivingthedesert’sexpansion,saysTaoWang,directoroftheColdandAridRegionsEnvironmentalandEngineeringResearchInstituteinLanzhou“ItlookslikethesamestoryastheDustBowl,”hesaysBattlecryTohelpwageawaronsomanyfronts,soilscientistsinthelatesembarkedonarapidefforttoformaglobalpictureofdegradationTheassessment,conductedbytheInternationalSoilandReferenceInformationCentre(ISRIC)intheNetherlands,surveyedmorethanexpertsonsixcontinentsandmappedoutwheresoilsarehurtingthemostTheresultswerestartling:OfthebillionhectaresofvegetatedlandonEarth,wasdegraded,largelythrougherosionofthisland,inhectarescouldnolongersupportcropsThemaincauses,accordingtothesurvey,weredeforestationandfarmingpracticessuchasovergrazingTheassessmenthasshortcomings:Itreliedonexpertopinionratherthandirectfielddata,forexample,andthemap’scoarsenessmeansthataregioncanbelabeleddegradedevenifitislargelyintactNevertheless,thesurveyhelped“putsoilinthepictureasanimportantresource,”saysISRICgeographerGodertvanLyndenRatchetingupthealarm,inthemidsagriculturaleconomistLesterBrown,thenpresidentoftheWorldwatchInstitute,athinktankinWashington,DC,warnedthatcivilizationriskedrunningoutofsoilbeforeoilHeestimatedthathumanactivitywasresponsibleforthelossofbilliontonsoftopsoilperyear,timesthenaturalrateInaninfluentialstudyadecadelater,CornellUniversityecologistDavidPimentelconcludedthatintheUnitedStatesaloneerosioninflictedaneyepopping$billionayearindamagetofarmland,waterways,infrastructure,andhealth(Science,February,p)Hepredictedthatiffarmersfailedtoreplacelostnutrientsandwater,UScropyieldswoulddropperyearBothconclusionshavebeenchallengedBrownarrivedathisglobalerosionfigurebyextrapolatingashakyUSestimatetotherestoftheworld,economistPierreCrossonlaternotedCrosson,whorecentlyretiredfromthenonprofitorganizationResourcesfortheFuture,alsotookaimatPimentel’scalculations,pointingoutthatthenumberswerebasedlargelyonmodels,notfielddata(Science,July,p)OhioState’sLalagreesthaterosionestimatesare“reallyverycrude”Basedonriversedimentationrates,Lalsays,humaninducederosionaveragesbilliontonsperyearwwwsciencemagorgSCIENCEVOLJUNECREDIT:DANIELLELUCCAWORLDBANKSOILSTHEFINALFRONTIERSPECIALSECTIONHealingtouchOneprovensolutiontorestoringsoilfertilityinsubSaharanAfrica’snutrientdepletedsoilsistoplantnitrogenfixingtreessuchasthesewinterthorn,growinginagroundnutfieldinSenegalFromAlaskatoYucatan,aLongAwaitedSoilSurveyTakesShapeSoilsareaspongeforpesticidesandothernastycompoundsfilteringdownfromthesurfaceYetexpertshaveonlyasketchyideaofhowthegroundcopeswiththistoxictricklecriticalinformationforanyandallcreatureslivingoffthelandThatfrustratingblindspotmaysoonchangeTheUSGeologicalSurvey(USGS)andahandfulofotheragenciesareplanninganambitiousmission:asoilgeochemicalsurveyofallofNorthAmericaTheimpetusforthesurvey,whichUSGSexpectstocosttensofmillionsofdollars,grewoutoftheneedformorecomprehensivedataonsoilcontaminantsRegulatoryagenciesarecryingoutforsuchdatatoimproveassessmentsofenvironmentalandhealthrisksForexample,informationonbackgroundlevelsofheavymetalssuchasarsenicandleadwouldhelpdeterminewhetherhumanactivitiesareraisingconcentrationstohazardouslevels,saysDavidMellard,atoxicologistattheUSAgencyforToxicSubstancesandDiseaseRegistry“Thereareliterallytensofmillionsofchemicalsinuseoutthere,”addsUSGSsoilscientistDavidSmith,whowithcolleagueMartinGoldhaberisleadingthesurvey’sfeasibilitystudyBut“ifyoudon’tknowwhat’scurrentlyinthesoil,”Smithasks,“howdoyouknowifit’sincreased”GeochemicaldatainNorthAmericaaresurprisinglyspottyThemostwidelyusedresource,theShacklettedataset,drawsonsoilsamplesfromnoncultivatedsites(aboutonepersquarekilometers,anarearoughlythesizeofthestateofDelaware)acrosstheUnitedStatesthatwerecollectedinthesand’sTheUSDepartmentofAgriculture’sNaturalResourcesConservationService(NRCS)followedwithaseparatelimitedsurvey,samplingagriculturalsitesforlevelsoffivemetalsimportantforcrops:cadmium,copper,lead,nickel,andzincNationwidedataarelargelylackingonorganiccontaminantsandmicrobialcommunitiesUSGS,alongwithNRCSandcounterpartsinCanadaandMexico,hopestobeginthedecadelongcontinentalsurveyinItwouldanalyzesoilsamplesfrom,

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