1、UniversityCode：10225RegisterCode：S15734DissertationfortheDegreeofMasterEffectofThinningIntensityonSoilCarboninLarixgmeliniiPlantationXgmellantCandidate：Supervisor：AssociateSupervisor：AcademicDegreeAppliedfor：Speciality：D

2、ateof0ralExamination：University：WangChangliangProfWangQingchengMasterSilvicultureJune2015NortheastForestryUniversityAbstractAbstractFortyyearslarixgmeliniiplantationwasstudiedatFenghuangMountainForestFarminHeilongjiangPr

3、ovinceLarchplantationsoilorganiccarbon(SOC)concentration，labileorganiccarbon(LOC)concentration，soilenzymeactivity，littercarbonstorage，soilrespirationratewereinvestigatedaftertwentysevenyearsthinning，withthreethinninginte

4、nsity(control(CK)，15％thinningintensity(T1)，40％thinningintensity(T2))TheeffectsofdifferentthinningtreatmentsonLarchplantationsoilsinkwereanalyzed，andtheinfluencemechanismofSOCconcentrationwithdifferentthinningtreatmentswa

5、sdiscussedTheresultsshowed：(1)ThinningpromotedSOCconcentration，onlyT1treatmentwassignificant(P005)and3831％(P005)(3)T1treatmentimprovethelarchplantationinsoilthesoilsucroseandamylaseactivity，werehigherthanCKsurfacelayer(0

6、10cm)by1979％and8308％respectivelyWithdecliningsoilsoilenzymeactivityofadownwardtrendAlltreatmentcarbonactivityinsurfacelayeristhelargest，andtheallsoillayerwere：T2TlCKWiththeincreaseofthinningintensity，carbonactivityandcar

7、bonmanagementindexwereincreasedSo40％thinningintensityofT2treatmentwasmorebeneficialtotheimprovementoftheplantatlonproductivity(41T1treatmentincreasedtheforestlitter，andpromotedforestlitterdecompositionThinningcouldreduce

8、thesoilrespirationrateWiththeglobalwarming，soilrespirationrateincreasedafterthinningisfarlessthanCKSothinning，especially15％thinningintensitywasmoreconducivetothesequestrationofsoilcarbonInconclusion15％thinningintensityof