简介：<正>Human’sancestorwasoriginallyamemberofthetenthousandthingsofcreation.Inalonghistoryafterenteringintocivilization.humanstillmaintainedharmonyandequilibriumwithnature.However,thehighlydevelopedmoderntechnologyandeconomysenthuman

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简介：ＶＩＬＬＡＧＥＦＯＲＥＳＴＲＹＳＴＡＴＩＯＮＳＰＥＲＦＯＲＭＡＮＩＭＰＯＲＴＡＮＴＲＯＬＥＩＮＣＨＩＮＡ’ＳＳＯＣＩＡＬＦＯＲＥＳＴＲＹＤＥＶＥＬＯＰＭＥＮＴＢｙＺｈｕＴｕｅ；ＷａｎｇＬｉｐｉｎｇ；ＳｈｉＷｅｎｋａｉＴｈｅＲｅｌａｔｉｏｎｓｈｉｐＢｅ...

简介：Background:Coarsewoodydebris(CWD)isanimportantelementofforeststructurethatneedstobeconsideredwhenmanagingforestsforbiodiversity,carbonstorageorbioenergy.Tomanageiteffectively,dynamicsofCWDdecompositionshouldbeknown.Methods:Usingachronosequenceapproach,weassessedthedecompositionratesofdownedCWDofFagussylvatica,PiceaabiesandPinussylvestris,whichwassampledfromthreedifferentyearsoftreefallandthreedifferentinitialdiameterclasses(>10–≤20cm,>20–≤40cm,>40cm).Samplesoriginatingfromwindthrowsin1999werecollectedalongatemperatureandprecipitationgradient.Basedonthedecayclassandassociatedwooddensities,logvolumeswereconvertedintoCWDmassandCcontent.Logfragmentationwasassessedoveroneyearforlogsegmentsofintermediatediameters(>20–40cm)after8and18yearsofdecomposition.Results:Significantlyhigherdecompositionconstants(k)werefoundinlogsofF.sylvatica(0.054year~(-1))thaninP.abies(0.033year~(-1))andP.sylvestris(0.032year~(-1)).However,masslossofP.sylvestrisoccurredmainlyinsapwoodandhencekforthewholewoodmaybeoverestimated.DecompositionratesgenerallydecreasedwithincreasinglogdiameterclassexceptforsmallerdimensionsinP.abies.About74%ofthevariationinmassremainingcouldbeexplainedbydecompositiontime(27%),treespecies(11%),diameter(17%),theinteractiveeffectsbetweentreespeciesanddiameter(4%)aswellasbetweendecompositiontimeandtreespecies(3%)andarandomfactor(siteandtree;9.5%),whereastemperatureexplainedonly2%.Woodfragmentationmayplayamoreimportantrolethanpreviouslythought.Here,between14%and30%ofthedecompositionrates(forthefirst18years)wereattributabletothisprocess.Carbon(C)density(mgC·cm~(-3)),whichwasinitiallyhighestforF.sylvatica,followedbyP.sylvestrisandP.abies,decreasedwithincreasingdecaystagetosimilarvaluesforallspecies.Conclusions:Theapparentlackofclimateeffectsondecompo

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简介：Background:Coarsewoodydebris(CWD)isveryimportantforforestecosystems,particularlyforbiodiversityandcarbonstorage.Itsrelevanceasapossiblereservoirandsourceofnutrientsislessclear,especiallyincentralEurope.Methods:Basedonachronosequenceofknownagesoflogs,weanalyzedthenutrientsstoredinCWDofFagussylvatica,Piceaabies,andPinussylvestrisatdifferentsitesinGermany.Toquantifynutrientconcentrations,weassessedtheuseofNearInfraredReflectanceSpectroscopy(NIRS)todeterminethechemicalpropertiesofCWD.Results:NIRSmodelsweresuitabletopredictconcentrationsofC,N,P,ligninandextractives.Concentrationsofmostnutrientsincreasedwithmassloss,withtheexceptionofpotassium,whichdecreasedforbeechandpineandremainedrelativelyconstantforspruce.Thehighestnutrientconcentrations(N,P,S,CaandMn,exceptMgandK)weregenerallyobservedinhighlydecomposedsprucelogs.TheneteffectofdecreasingCWDmassandincreasingnutrientconcentrationswaseitheradecreasing(N,PandKinbeech;P,Mg,KandMninpine),constant(S,CaandMginbeech;N,SandCainpine)orincreasingamountofnutrients(N,P,SandCainspruce;Mninbeech)inthelogsoverthecourseofdecomposition.TheC/Nratiodecreasedforalltreespecies,mostmarkedlyforsprucefromca.1000atthebeginningofthedecompositionprocessto180at36years.TheN/Pratioconvergedtoavalueofabout30forallthreespecies.Ligninconcentrationsincreasedforspruceandbeechandremainedconstantforpine.Conclusions:OurresultsindicatethatmostnutrientsremaininCWDforlongperiods.NutrientsmaybeusedandcycledbymicroorganismswithinCWD,butwiththeexceptionofP(inbeech),Mg(inpine)andK(inbeechandpine),thereappearstobelittlenetnutrientexportuntiltwothirdsofthemassislost.Instead,N,P,SandCawereaccumulatedinsprucelogs,indicatingthatCWDbecameanetsinkratherthananetsourceofsomenutrientsforsevera