简介：Background:Soilorganiccarbon(SOC)isalargereservoirofterrestrialcarbon(C);itconsistsofdifferentfractionsofvaryingcomplexityandstability.PartitioningSOCintodifferentpoolsofdecomposabilityhelpbetterpredictthetrendofchangesinSOCdynamicsunderclimatechange.InformationonhowphysicalfractionsandchemicalstructuresofSOCarerelatedtoclimateandvegetationtypesisessentialforspatialmodelingofSOCprocessesandresponsestoglobalchangefactors.Method:Soilsampleswerecolectedfrommultiplerepresentativeforestsitesofthreecontrastingclimaticzones(i.e.cooltemperate,warmtemperate,andsubtropical)ineasternChina.MeasurementsweremadeonSOCcontentsandphysicalfractionsofthe0–20cmsoillayer,andthechemicalcompositionofSOCofthe0–5cmsoillayer,alongwithmeasurementsandcompilationofthebasicsiteandforeststandvariables.Thelong-termeffectsoftemperature,litterinputs,soilcharacteristicsandvegetationtypeontheSOCcontentsandfactionswereexaminedbymeansof"spacefortimesubstitution"approachandstatisticalanalysis.Result:Meanannualtemperature(MAT)variedfrom2.1℃atthecooltemperatesitesto20.8℃atthesubtropicalsites.TotalSOCofthe0–20cmsoillayerdecreasedwithincreasingMAT,rangingfrom89.2g·kg^-1incooltemperateforeststo57.7g·kg^-1insubtropicalforests,atanaveragerateof1.87%reductioninSOCwitha1℃increaseinMAT.WithincreasingMAT,theproportionsofaromaticCandphenolicCdisplayedatendencyofdecreases,whereastheproportionofalkylCandA/O-Avalue(theratioofalkylCtothesumofO-alkylCandacetalC)displayedatendencyofincreases.Overall,therewerenosignificantchangeswithMATandforesttypeineitherthephysicalfractionsorthechemicalcomposition.BasedontherelationshipbetweentheSOCcontentandMAT,weestimatethatSOCinthetop20soillayerofforestspotentiallycontribute6.58–26.3PgCgloballytotheat