聪明文档网

    聪明文档网

    最新最全的文档下载
    当前位置： 首页> 翻译英文版

    翻译英文版

    时间：    下载该word文档
    EffectsofsandydesertifiedlandrehabilitationonsoilcarbonsequestrationandaggregationinanaridregioninChina
    YongZhongSua,b,*,XueFenWanga,RongYanga,JaehoonLeec
    abstract
    Therehabilitationofsandydesertifiedlandinsemi-aridandaridregionshasagreatpotentialtoincreasecarbonsequestrationandimprovesoilquality.Ourobjectivewastoinvestigatethechangesinthesoilcarbonpoolandsoilpropertiesofsurfacesoil(0–15cmunderdifferenttypesofrehabilitationmanagement.Ourstudywasdoneintheshort-term(7yearsandlong-term(32yearsdesertificationcontrolsitesinamarginaloasisofnorthwestChina.Thedifferentmanagementtreatmentswere:(1untreatedshiftingsandlandascontrol;(2sand-fixingshrubswithstrawcheckerboards;(3poplar(Populusgansuensisshelterforest;and(4irrigatedcroplandafterlevelingsanddune.TheresultsshowedthattherehabilitationofseveresandydesertifiedlandresultedinsignificantincreasesinsoilorganicC(SOC,inorganicC,andtotalNconcentrations,aswellasenhancedsoilaggregation.Overa7-yearperiodofrevegetationandcultivation,SOCconcentrationintherecoveredshrubland,forestlandandirrigatedcroplandincreasedby4.1,14.6and11.9timescomparedtothecontrolsite(shiftingsandland,andincreasedby11.2,17.0and23.0timesoverthe32-yearrecoveryperiod.TotalN,labileC(KMnO4–oxidationC,Cmanagementindex(CMIandinorganicC(CaCO3–CshowedasimilarincreasingtrendasSOC.TheincreasedsoilCandNwaspositivelyrelatedtotheaccumulationoffineparticlefractions.Theaccumulationofsiltandclay,soilCandCaCO3enhancedtheformationofaggregates,whichwasbeneficialtomitigatewinderosion.Thepercentageof>0.25mmdryaggregatesincreasedfrom18.0%inthecontrolsiteto20.0–87.2%intherecoverysites,andthemeanweightdiameter(MWDofwater-stableaggregatessignificantlyincreased,witharangeof0.09–0.30mmattherecoverysites.Long-termirrigationandfertilizationledtoagreatersoilCandNaccumulationincroplandthaninshrubandforestlands.TheamountofsoilCsequestrationreachedupto1.8–9.4and7.5–17.3Mgha1atthe0–15cmlayerovera7-and32-yearrehabilitationperiodcomparedtothecontrolsite,suggestingthatdesertificationcontrolhasagreatpotentialforsequesteringsoilCandimprovingsoilqualityinnorthwestChina.
    1.Introduction
    Desertificationisdefinedaslanddegradationinarid,semi-aridanddrysub-humidareasresultingfromvariousfactorsincludingclimaticvariationsandhumanactivities(UNEP,1990.Landdesertificationleadstodeclineinsoilstructureandreductioninaggregation,andinturn,leadstoreductioninthetotalsoilcarbonpoolandemissionofCO2fromsoilandvegetationtotheatmosphere,andtherefore,impactedtheglobalCcycle(Lal,2001;Jabroetal.,2008;Yuetal.,2007.Itisestimatedthatdesertificationaffectsabout1.137Bhaofsoilsandanadditional2.576BhaofrangelandvegetationindrylandsaroundworldandthetotalhistoriclossofCduetodesertificationmaybe18–28Pg(Lal,2001,indicatingthatlanddesertificationcharacterizedbysoildegradationanddiminutionordestructionofbiologicalpotentialofecosystemshaveplayedanimportantroleinatmosphericenrichmentofCO2.RestoringthesesystemsthroughtheadoptionofappropriatelandusepracticessuchasrevegetationwouldincreasethepoolofCinsoilandbiomassandyieldsignificantecosystemcarbongains(Nosettoetal.,2006.Sandy

    desertificationunderthewindandsandactivitiesisoneofthemainformsoflanddesertification(Wangetal.,2004.Chinaisoneofthemostseveresandydesertificationcountries.Theresultsofmonitoring,basedonremotesensing,showedthatthetotalareaofsandydesertifiedlandinnorthChinawas38.57Mhain2000(Wangetal.,2004.Fengetal.(2001estimatedthatdesertlandsinnorthChinacausedanetemissionof2.17PgofCoverthepast40-yearperiodduringthe1950s–1990s.InthesemiaridHorqinsandylandofnortheastChina,Zhouetal.(2008estimatedthetotallossofsoilorganiccarbonresultingfromdesertificationwas107.53Mtonlandareaof26,393haduringthelastcentury.
    DesertificationcontrolhasbeenconsideredasaprincipalstrategytomaintainecologicalsecurityinnorthChina.Inthepastseveraldecades,someeffectivemeasuresofdesertificationcontrolhavebeenwidelyappliedindesertifiedzonefromnortheasttonorthwestChina.Successfulmeasuresincludedtheestablishmentofprotectiveforestbeltsandsand-fixingshrubforest,theretirementofdegradedmarginalcroplandintoforestorgrassland,theprohibitionoflivestockgrazingtorecovervegetationindesertifiedgrassland(ResearchGroupofStudyonCombatingDesertification/LandDegradationinChina,1998.DesertificationcontrolindesertifiedlandsofnorthChinawerealsoreportedtoenhancesoilCsequestration(Fengetal.,2001;Lal,2002;Wangetal.,2008becausedesertificationcontrolcouldeffectivelydecreasewinderosionandimprovesoildevelopment,andinturn,enhancesoilCcontentthroughincreaseinnetprimaryproductivityandbiomassreturnedtothesoil(SuandZhao,2003;Duanetal.,2004;Lietal.,2007;Suetal.,2007a.TheincreasedsoilCcontentcanenhancetheformationofsoilaggregates(BronickandLal,2005,andthereforetostabilizeshiftingsand.
    AccurateestimateforsoilcarbonsequestrationpotentialthroughrehabilitationofdesertifiedlandsneedtobesupportedbyaseriesofresearchesinvariousregionsinnorthChina.Especially,researchesfromlong-termobservationsitesintypicalareasofdesertificationcontrolareveryimportantforevaluatingsoilcarbonsequestrationeffectofdesertifiedlandrehabilitation.Theobjectiveofthisstudywastoevaluatetheshort-andlong-termeffectsoftheestablishmentofvegetationanddesertifiedlandrehabilitationonsoilcarbonsequestrationandaggregationintheextremelyaridregioninnorthwestChina.2.Methods
    2.1.Sitedescription
    Thestudysite,coveringPingchuanmarginaloasis,LinzecountyinthemiddleofHexiCorridorregionofGansuprovince,islocatedbetween39090–39190Nand100020–100210EatthesouthernedgeofBadanJaranDesert,withanaltituderangingfrom1368to1380m(Fig.1.ThemarginaloasisisconnectedwithdensemovinganddenudationresidualdunesaswellasGobi.Theregionhasatypicaltemperatedesertclimate:dryandhotinsummer,coldinwinter,plentyofsunshine,verylittleprecipitation,strongwinds,andfrequentdriftingsands.Themeanannualprecipitationwithintheregionencompassingthestudysiteswas117mm.Andthemeanannualairtemperatureis7.6C,withanabsolutemaximumof39.1Candanabsoluteminimumof27C.Meanannualpanevaporationisaround2390mm.Meanannualwindvelocityis3.2ms1,andprevailingwinddirectionisnorthwest.Galeswithwindvelocity>17ms1occur15ormoredaysperyear(Suetal.,2007a.Thedepthofgroundwater

    levelrangesfrom4to10m.ThemainsoiltypesareAripsammentandCalciorthidswithloosestructureandveryloworganicmatter,andareverysusceptibletowinderosion(Chenetal.,1998.ThenaturalvegetationattheedgeofoasiscomposedofsomedesertshrubsincludingCalligonummongolicumTurcz.,CalligonumgobicumA.Los.,HaloxylonammodendronBge.,CaraganakorshinskiiKom.,HedysarumscopariumFisch.etMey.,andTamarixchinensisLour.,andsomesmallsubshrubssuchasNitrariasphaerocarpaMaxim.andReaumuriasoongoricaMaxim.Thestaplecropsarespringwheat(Triticumaestivum,maize(Zeamaysandcotton(Gossypiumhirsutumintheoasis.
    In1975,LanzhouInstituteofDesertResearch,ChineseAcademyofSciencesestablishedtheLinzeStationofDesertificationResearchinPingchuanandconductedadesertificationcontrolprojecttomonitordesertificationprocessesanddevelopeffectivetechniquestorestorevegetationandrehabilitatedesertifiedland.Therehabilitationtechniquesappliedincludedestablishingstrawcheckerboardsassandbarrierandplantingdrought-tolerantindigenousdesertshrubswithincheckerboardsonmobilesanddunes,plantingfast-growingtreesatthefringeofoasisasprotectingforestbelts,andreclaimingsandylandasirrigatedcropland(Suetal.,2007a.Aftertheprojectwasfinished,therateofshiftingsandareaintherestorationsitedeclinedfrom54.6%inpre-treatmentto9.4%(ResearchGroupofStudyonCombatingDesertification/LandDegradationinChina,1998.In2000,asimilarprojectwasconductedinadjacentrehabilitatedareaandthesamerehabilitationtechniqueswereapplied.Therecoveryobservationsitesestablishedindifferentperiodsprovidedussufficientinformationtoevaluatetheecologicaleffectofdesertifiedlandrehabilitation.

    2.2.Fieldandlaboratorymeasurements
    2.2.1.Experimentdesignandsoilsampling
    In2007,weselectedtwostudysitesadjacentrehabilitationareasabout2kmawayfromtherecoverysitesestablishedin1975and2000.Beforetherehabilitation,thelandscapeofthetwoareaswasdenudationandshiftingsanddunes.Previousanalysisofsoilpropertiesindifferentperiodsshowedthatsoiltextureandorganiccarbonconcentrationinsoilprofilewerenotsignificantlydifferentontheshiftingsanddunesovertime(Chenetal.,1998;Suetal.,2007a.Thissuggestedthatthesoilshaverelativelysimilarcharacteristicsbeforetherehabilitation.Therecoverytreatmentsappliedinthetwoperiods(7-and32-year-oldincludedestablishingstrawcheckerboardsassandbarrierandplantingHaloxylonammodendron,establishingpoplar(Populusgansuensisshelterforestbelts,andlevelingsanddunesasirrigatedcropland.Therefore,ourtreatmentsincluded:(1control(untreatedshiftingsandland;(27-year-oldH.ammodendronshrubland;(332-year-oldH.ammodendronshrubland;(47-year-oldpoplarshelterforestland;(532-year-oldpoplarshelterforestland;(67-year-oldreclaimedirrigatedcropland;and(732-year-oldreclaimedirrigatedcropland.Table1showsthecharacteristicsandmanagementofthedifferentlandcovertypes.Withineachtreatmentrecoverysite,weselectedthree2020mquadratsassoilsamplingsites.Withineachquadrat,fivesoilsamplesat0–15cmlayerwithuniformdistributionseparatedby5meachweretakenandbulkedtoobtainacompositesample.OntheH.ammodendronshrublands,tensamples(fiveweredistributedundercanopyandothersoutsidecanopyweretakenandmixedineachsamplingquadrat.Soilbulkdensitywas

    determinedusingasoilcore(100cm3takenineachsamplinglocation.Afterairdrying,eachcompositesamplewassplitintotwosubsamples.Onesubsamplewassievedto<2mmfortheanalysisofsoilparticledistributionandto<0.1mmforthedeterminationofsoilorganicC,totalN,CaCO3,andlabileC(KMnO4oxidationC.Theothersubsampleofsoilwassievedto<8mmsieveforaggregatestabilitydetermination.2.2.2.Soilanalyses
    Soildryaggregatesizedistributionwasdeterminedbymanualdrysievingmethod(InstituteofSoilSciences,ChineseAcademyofSciences,1978.100–150gair-driedsoilsampleswerepassedthrough8mmscreenandthenplacedonthetopofnestoffivesieveswithsquareopeningsof5,2,1,0.5and0.25mm.Thesieveswerethenoscillatedrhythmicallybyhandfor5min.Drysoilsremainingoneachsievewascollectedandweighedtogetdryaggregatesizedistraggregatesibution.Thedeterminationofwater-stablewasperformedusingawetsievingprocedure(KemperandRosenau,1986.A50gofair-driedsoilsample(<8mmwasplacedontothetopofthefivesieves(5,2,1,0.5and0.25mm,andgentlymoistenedtoavoidasuddenruptureofaggregates.Afterthesoilhadbeenmoistened,thesetwassieved10minindistilledwateratthe30oscillationsperminute,andthesoilremainingoneachsievewasdried.Sandcontentoftheaggregateswasdeterminedonasubsampleofaggregatesthatweredispersedwith0.5%sodiumhexametaphosphate.Themeanweightdiameter(MWDofsand-freeaggregateswascalculatedasfollows:
    whereWiisthemasspercentageofaggregateremainingonithsieve;andXiistheaveragediameterofthetwoadjacentsizeclasses.
    Soilparticlesizedistributionwasdeterminedbythepipettemethodinasedimentationcylinder,usingsodiumhexametaphosphateasthedispersingagent(GeeandBauder,1986.Soilorganiccarbon(SOCwasdeterminedbydichromateoxidationofWalkley–Black(NelsonandSommers,1982,andtotalNwasmeasuredbymicro-Kjeldahalprocedure.Thecontentofcarbonate,expressedasCaCO3,wasdeterminedbytheCO2volumetricmethod(InstituteofSoilSciences,ChineseAcademyofSciences,1978.
    LabileC(CLwasdeterminedbyoxidationwith333mmolL1KMnO4accordingtothemethodofBlairetal.(1995.Non-labileC(CNLwascalculatedfromthedifferencebetweenorganicCandCL.Carbonmanagementindex(CMI,usedasanindicatorofthestateandrateofchangeinsoilCofagriculturalandnaturalsystems,wascalculatedforeachofthetreatmentsusingtheuntreatedsandlandsoilasthereference(Blairetal.,1995.
    Statisticalanalysis(ANOVAwithLSDandregressionanalysiswasdonebyusingSPSS10.0ataP<0.05significancelevel.3.Results
    3.1.SoilparticlesizedistributionandbulkdensityThestudyareahaveasandylayer1mormoreinsoilsinthethickness,mainlyconsistingofwellsortedmedium-finesand.Intheuntreatedcontrolarea,totalsandcontentaveraged95.2%andthemedium-finesandfraction(1–0.1mmwastheprevalentcomponent(82.4%.Aftertherevegetationandreclamationfor7nd32years,significantchangesinsoilparticlesizedistributionoccurredinalltreatments.Incomparisontothecontrol,mediumfinesandcontentinrehabilitationsitesdecreasedby10.9–56.3%,andveryfinesandandsiltincreasedby31.2–240%and2.2–8.8times,respectively.Thegreatestandsmallestchangesinparticlesizedistributionoccurredonthe32-year-oldirrigatedcroplandandontheH.ammodendronshrubland,respectively.Followingrevegetationandreclamation,silt

    fractionshowedthemostsignificantchange.Owingtothechangesinsoilparticlesizeistribution,thebulkdensityintherestorationareadecreased,especiallythe32-year-oldcropland(Table2.Incomparisonwiththesamerehabilitationtypewithdifferentperiods,nosignificantdifferenceinsoilparticlesizedistributionwasobservedbetweenthe7-and32-year-oldshrublands.Soilmedium-finesandcontentwaslowerandboththeveryfinesandandsiltfractionsweregreaterinthe32-year-oldpoplarshelterforestlandcomparedtothe7-year-oldforestland,andsignificantdifferencewasobservedinmedium-fivesandandsiltfractions.Allparticlefractionsshowedverysignificantdifferencesbetweenthe7-and32-year-oldcroplands(Table2.3.2.Soilaggregation
    Soilaggregatesizedistributiondifferedamongthedifferenttreatments.Inthecontrolsite(shiftingsandland,thesurfacelayerwascomposedofwellsortedandseparatedmediumandfinesand.Afterdrysieving,themassproportionof1–0.5and0.5–0.25mmfractions(sandwas18%andno>1mmaggregateswereobserved.Intherehabilitationandreclamationsites,themasspercentageofthe>0.25mmdryaggregatesrangedfrom20.0to87.2%withthegreatestoncroplandandthelowestonshrubland.Theproportionofnon-erodiblefractions(>1mmaggregatesrangedfrom8.6to70.4%.Distributionofdryaggregatesindicatedthehighestcontentinthe>5mmdiameterclassforalltreatments.Afterwetsieving,alargepartofdryaggregatesbrokenintosmalleraggregatesorsinglegrainandthecontentofthe>0.25mmwater-stableaggregatesrangedfrom5.9to20.6%.Themeanweightdiameter(MWDrangedfrom0.09to0.30mm.Incomparisonwiththesamerehabilitationtype,MWDwassignificantlylargerinthe32-year-oldrecoverysitethaninthe7-year-oldrecoverysite(Table3.3.3.Soilcarbonandnitrogen
    Comparedwiththeuntreatedshiftingsandlandsoils,SOCconcentrationinthe0–15cmsurfacelayerincreasedby4.1–11.2timesfortheshrublandsoils,14.6–17.0timesfortheforestlandsoils,and11.9–23.0timesfortheirrigatedcroplandsoils.ThetotaNconcentrationincreasedby1.9–8.1timesunderthedifferentrehabilitationtypesandagescomparedtothecontrolsoil.ThepercentageofincreaseinthetotalNcontentwassmallerthanthatofSOCincrease,thustheC/Nratiossignificantlyincreasedintherehabilitationandreclamationsites.ThereweresignificantdifferencesinSOCconcentrationamongthesoilsinthethreedifferentrehabilitationtypeswithinthesameperiodsandbetweenthesoilsinthetwoperiodswiththesamerehabilitationtreatments(Table4.ItwasnotedthatnosignificantdifferenceintotalNconcentrationwasobservedbetweenthe7-and32-year-oldforestlandsoils(Table4.Followingtherehabilitationandreclamation,theconcentrationofsoilinorganicC(SIC,CaCO3–Calsoincreasedby10.2–45.7%over7yearsand28.8–79.8%over32yearscomparedtothecontrolsoils(Table4.ThesmallestchangeinSICconcentrationoccurredintheshrubland,andnosignificantchangewasobservedbetween7-yearshrublandandthecontrolsite.
    TheshiftingsandlandshowedaverylowlabileC(KMnO4extractableCconcentration.Followingrehabilitation,labileChadasimilarincreasingtrendtoSOC.TheCMIofshrubland,forestlandandcroplandincreasedby2.5,10.1and6.9timesduring7-yearrehabilitationperiodand6.6,14.9and21.7timesduring32-yearperiod,respectively.
    WhentheSOCandSICconcentrationsweretransformedtomassperhectare,totalsoilCincreasesoftheshrubland,forestlandandcroplandsoilsrelativetothecontrolsoilswere1.8,10.6and9.4Mgha1duringthe7-yearrehabilitationperiod,and7.5,15.4and17.3Mgha1duringthe32-yearrehabilitationperiod,respectively(Fig.2.

    3.4.RelationshipsofsiltþclayandaggregationwithCfractionsandN
    TherewerepositivecorrelationsofSOC,totalNconcentrationwithsiltþclaycontent,indicatingthattheaccumulationandinputoffinematerialsinthetopsoillayersignificantlycontributedtotheincreasesofSOCandNconcentration(Fig.3.ThereweresignificantlinearrelationshipsofSOC,CaCO3,andlabileCconcentrationwithMWD.TheR2values(rangedfrom0.52to0.63showedthatthereisastrongercorrelationofSOCandCaCO3withMWDthanLabileCwithMWD(Fig.4.4.Discussions
    OurstudyshowedthatplantingH.ammodendrononshiftingsandduneresultedintheaccumulationoffineparticlesinthetopsoil.TheresultwasinlinewiththepreviousworkofFearnehoughetal.(1998andLietal.(2006bwhoreportedthatestablishingstrawcheckerboardandrevegetationfacilitatedtheentrapmentandretentionofmoreaeoliandustincludingdustfromatmosphere.Whentheshiftingsandduneswereleveledandchangedintotheirrigatedcroplandandforestland,thelong-termuseofsilt-ladenwaterforirrigationsignificantlyincreasedfinefractionsintopsoil.Furthermore,long-termfarmyardmanure(soilcompostapplicationbroughtmorefinematerialsintocroplandsoils.
    Increasedfineparticlesacceleratedtheformationofaggregatesandthedevelopmentofsoilstructure.AftertheestablishmentofH.ammodendrononshiftingsanddunefor7and32years,thesandsurfacewascoveredbya0.5–2and2.5–5.0cmdepthcrustlayer,respectively.Thesoilcrustwasakindofplatyaggregatesthatwasbondedtheseparatedsandswithfineparticles,organicmatter,andCaCO3.Thecomponentofdryaggregateswasdominantinthe>5mmblockmacroaggregatesintheirrigatedcropland.Thischaracteristicofdryaggregatesizedistributionisbeneficialforreducingwinderosionandtheformationofdustintheeventofstorm.However,alargepartofmacroaggregates(>5mmhasbrokenintosmallaggregatesandsingleparticlesafterwetsieving,suggestingthatthestabilityofaggregateswaspoor,witharelativelysmallMWDforalltreatments(rangedfrom0.09to0.30mm.ThepositiverelationshipsbetweenaggregatestabilityandSOC,CaCO3andlabileCwerefound,andMWDshowedastrongerrelationshipwithCaCO3thanwithSOCandlabileC(Fig.3.ThissuggestedtheimportanceofSOCandCaCO3concentrationonsoilaggregationinaridregion(BronickandLal,2005;Suetal.,2007b,andCaCO3hadagreatereffectonMWDinthesoilswithlowCconcentrationsinthisregion.
    TheresultsindicatedasignificantincreaseinSOCconcentrationandpoolfollowingtherevegetationandcultivationofdesertifiedland,whichisinaccordancewithLal(2001,2002,2004andSartorietal.(2007whosuggestedthattherehabilitationofdesertifiedlandandtheadoptionofrecommendedmanagementpractices(includingirrigation,conversionofdesertlandtointensivelymanagedpoplarplantationhadasignificantsoilcarbonsequestrationeffect.Inourstudy,theincreasesinSOCvariedunderdifferentrehabilitationtreatmentsandages.Inthelessmanaged(noirrigationandfertilizationshrubland,SOCaccumulationwasslowerthanforestlandandcropland.SoilCaccumulationfortheshrublandhadsimilarresultsreportedinotherstudiesinthedesertificationregionsofnorthChina.Forexample,aresearchfromtheShapotouDesertResearchandExperimentStationshowedthatsoilorganicandinorganicCcontentsincreasedexponentiallyfollowingtheestablishingstrawcheckerboardsandplantingdesertshrubsinsandduneasrecoveryperiodincreases(Lietal.,2007.AnotherstudyshowedthatsoilorganicCconcentrationatthe0–5cmtopsoilincreasedfrom0.35gkg1atthecontrolsiteto0.71gkg1atthe6-year-oldrecoverysiteand7.77gkg1atthe50-year-oldrecoverysite,respectively(Lietal.,

    2006b.Insemi-aridHorqinsandylandofNortheastChina,SuandZhao(2003reportedthataftertheestablishmentofCaraganamicrophyllaonshiftingsanddunefor5and28years,SOCconcentrationatthe5cmlayerincreasedby13.3timesand20.5times,respectively.
    Comparedtoshrubland,theforestlandreceivedgreateramountsoflitterfallinputsandthedepositionofmorefineparticlesthroughirrigationwithsilt-ladenwater3–5timeseachyear,whichresultedinagreaterCandNaccumulationinforestlandthaninshrubland.Especially,forthe7-year-oldpoplarplantation,alfalfaforagewasplantedinalleywhenplantingpoplarseedlingsandagivenamountofNandPfertilizerswereappliedeachyearatthefirst4years.Fouryearslater,alfalfadiedduetoshadingofpoplar,andlefttheamountofplantresidueintopsoil,whichresultedinarelativelyrapidCandNaccumulationwithinashort-termperiod.WebelievethattheincreaseinSOCandtotalNincroplandsoilsiscausedbytheinputsofsoilfinematerialsthroughirrigation8–11timeseachyearandpartlyfromtheinputsoffarmyardmanureandplantrootbiomassofcultivationofcrops.TheaccumulationofSOCandtotalNinthereclaimeddesertsoilwasinaccordancewiththeresultsfromLietal.(2006awhoreportedanincreasingpatterninSOCwiththedurationofthecultivationperiod.TheresultsalsoconfirmedthattheinputsoffineparticlesplayanimportantroleintheprocessofsoilCsequestrationforthesecoarse-texturedsoils(Lietal.,2006a;Suetal.,2007a,asindicatedbysignificantrelationshipsofsoilorganicC,SICandlabileCwithsiltandclaycontent.TheincreasedsoilinorganicC(CasCaCO3intherehabilitationandcultivationsiteswasresultedfromtheinputsoffineparticlesthroughdust-fallandirrigation,aswellasapplicationoffertilizers.IigationandfertilitymanagementcanincreaseSOCtherebyacceleratingformationofsecondarycarbonatesinaridandsemiaridsoilsthroughtheadditionofcarbonicandorganicacidsthatcanreactwithsoilsilicates(Schwartzmanetal.,1994.AgreaterincreaseofSICcontentinirrigatedcroplandagreeswiththeresultsofEntryetal.(2004andWuetal.(2008,whoreportedthatirrigationsignificantlyincreasedinorganiccarboninagriculturalsoilsofaridandsemi-aridregions.
    Whitbreadetal.(1998reportedthatlabileCincreasedfasterandmoreresponsivethantotalsoilCtochangingmanagementpracticesintheshort-term.Inourstudy,however,revegetationandcultivationforover7yearshadincreasedSOCby3.7–14.6timesandlabileCby3.3–13.7timescomparedwiththecontrol.ThismaybeattributedtomoreCinputsthroughtheincreasedfineparticlesandrelativelylessCinputsthroughplantresidue.TheintegrationofbothSOCpoolandlabileCintotheCmanagementindex(CMIcanprovideausefulparametertoassessthecapacityofmanagementsystemsforpromotingsoilquality(Blairetal.,1995;Vieiraetal.,2007.ThehighestCMIvalueforcroplandsoilwith32yearcultivationisassociatedwiththeinputoflong-termirrigationandfertilization.Fortheshort-termrevegetationandcultivation(7years,thehighestCMIvaluewasfoundinforestland,mainlyduetotheinputofalfalfaresidues.
    SoilCsequestrationwassignificantlyincreasedintherehabilitationandcultivationsites,confirmingthatdesertificationcontrolhaveagreatpotentialforsequesteringcarbon(Lal,2001,2002anderosion.Long-termirrigationandapplicationofchemicalfertilizersandfarmyardmanureledtoagreatersoilCandNaccumulationincroplandthaninshrubandforestland.Thereisagreatneedtofurtherstudyandmonitortheeffectsofthesedesertificationcontrolsonvarioussoilandenvironmentalproperties.
    Acknowledgements
    Authorsthankreviewersforconstructivecomments.ThisresearchwassupportedbytheNationalNaturalScienceFoundationofChina(30670375andoneoftheMajorStateBasic

    ResearchDevelopmentProgram(2009CB421302.

    免费下载 Word文档免费下载： 翻译英文版

    TOP热门搜索

    相关推荐：

    工作汇报材料

    • ￥29.8

      ￥45 每天只需1.0元
      1个月 推荐

    • ￥9.9

      ￥15
      1天

    • ￥59.8

      ￥90
      3个月

    选择支付方式

    • 微信付款
    会员须知 联系在线客服 登录账号
    郑重提醒：支付后，系统自动为您完成注册

    请使用微信扫码支付(元)

    订单号：
    支付后，系统自动为您完成注册
    遇到问题请联系 在线客服

    常用手机号：
    用于找回密码
    图片验证码：
    看不清？点击更换
    短信验证码：
    新密码：
     
    绑定后可用手机号登录
    请不要关闭本页面，支付完成后请点击【支付完成】按钮
    遇到问题请联系 在线客服

    侵权投诉  © 2013-2019 http://www.tcm999.cn   站点地图 |  手机版

    本站文档均来自互联网及网友上传分享，本站只负责收集和整理，有任何问题可通过上访投诉通道进行反馈