Controlling Factors of Soil RespirationGlacier Forehead in Gongga Mountain ChinaWord文档格式.docx
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Temporal-spatialVariationandControllingFactorsofSoilRespirationinDifferentPrimarySuccessionStagesonGlacierForeheadinGonggaMountain,China
AuthorsandAffiliations
JiLuo1,YouchaoChen1,2*,YanghongWu1,PeiliShi3,JiaShe1,2,PengZhou1,2
1.InstituteofMountainHazardsandEnvironment,ChineseAcademyofSciences&
MinistryofWaterConservancy,Chengdu,China
2.GraduateSchooloftheChineseAcademyofSciences,Beijing,China
3.InstituteofGeographicSciencesandNaturalResourcesResearch,ChineseAcademyofSciences,Beijing100101,China
*Correspondingauthor.InstituteofMountainHazardsandEnvironment,ChineseAcademyofSciences&
MinistryofWaterConservancy,#9,Block4,RenminnanRoad,Chengdu610041,China.Tel.:
+86-18782109121;
Fax:
+86-028-85222258;
E-mailaddress:
whchenyouchao@
Abstract
Soilrespiration(SR)isanimportantprocessintheglobalcarboncycle.ItisdifficulttoestimateSRemissionaccuratelybecauseofitstemporalandspatialvariability.PrimaryforestsuccessiononGlacierforeheadprovidestheidealenvironmentforexaminingthetemporal-spatialvariationandcontrollingfactorsofSR.However,relevantstudiesonSRarerelativelyscarce,andvariations,aswellascontrollingfactors,remainuncertaininthiskindofregion.Inthisstudy,weusedastaticchambersystemtomeasureSRinsixsiteswhichrepresentdifferentstagesofforestsuccessiononforeheadofatemperateglacierinGonggaMountain,China.Ourresultsshowedthattherewassubstantialtemporal(coefficientofvariation(CV)rangedfrom39.3%to73.9%)andspatial(CVrangedfrom12.9%to67.6%)variationinSR.Soiltemperature(ST)at5cmdepthwasthemajorcontrollingfactoroftemporalvariationinallsixsites.SpatialvariationinSRwasmainlycausedbydifferencesinplantbiomassandTotalNamongthesixsites.Moreover,soilmoisture(SM),microbialbiomasscarbon(MBC),soilorganiccarbon(SOC),pHandbulkdensitycouldinfluenceSRbydirectlyorindirectlyaffectingplantbiomassandTotalN.Q10values(rangedfrom2.1to4.7)increasedalongtheforestsuccession,andthemeanvalue(3.3)waslargerthanthatoftemperateecosystems,whichindicatedageneraltendencytowardshigher-Q10incolderecosystemsthaninwarmerecosystems.Ourfindingsprovidedvaluableinformationforunderstandingtemporal-spatialvariationandcontrollingfactorsofSR.
Introduction
Astheimplicationsfortheclimatesystems,carbon(C)cyclehasreceivedgrowingattentioninrecentyear[1,2].SoilsconstitutethemajorCreserveinterrestrialecosystems[3],andsoilrespiration(SR),whichfollowsgrossprimaryproduction(GPP)asthesecondlargestCfluxintheglobalterrestrialCcycle[4],isacriticalecosystemprocessthatregulatesCcycleintheearthsystem.Becauseofthelargeflux,evenasmallchangeinSRratewouldhaveprofoundimpactontheatmosphericCO2concentration[5].Therefore,accuratelyquantifyingSRemissioniscrucialfortheclimatechangeprojects.However,anobstacletoestimatingSRemissionaccuratelyisitsinherenttemporalandspatialvariabilitywithinandacrossecosystems[6,7,8].
Soiltemperature(ST)andsoilmoisture(SM)arereportedastwomaincontrollingfactorsontemporalvariationofSR[9,10].Somebioticvariables,suchasmicrobial,rootandlitterbiomass,mayalsostronglyinfluencetheseasonalvariabilityofSR[11].ThespatialvariationofSRhasoftenbeenrelatedtoeithertheabioticfactors,suchasST,SM,soilorganiccarbon(SOC),soiltotalnitrogen(TotalN),soilbulkdensity,soilporosity,soilpH,orbioticfactors,suchasplantrootdensity,microbialbiomass,litteramount[12,13].However,theaccountabilityoftheseabioticandbioticvariablesontemporalandspatialvariationofSRwillbedependentonthetypeofecosystemsbeingstudied[14].
Forestsuccessionisafundamentalecologicalprocesswhichcanmodifybiogeochemicalcycles[15],amelioratestandconditionsandaltermicroclimatefactors[16].Asforestsdevelopfromyoungtomaturedevelopmentalstages,thedifferencesinsoilcarbonpools,rootbiomass,soilmicrobialbiomass,soilchemicalandphysicalproperties,etc,maycauseSRvariedwithinandacrosssites[17,18,19].ManyofthecontrollingfactorscompoundedinSRchangeduringthecourseofforestsuccession,thusmoreknowledgeofSRchangesalongwithaforestsuccessionalgradientisrequired.Primaryforestsuccessioncantakeplaceonglacierforehead,withrecedingicecoverpresentingachronosequenceofdevelopmentfromthebaresubstratetocomplexplantcommunities[20,21].Astheforeheadofaglacierissensitivetoclimatechange[22],forestsuccessiononglacierforeheadistheidealenvironmentforexaminingtheSRandcarbonc