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简介：Theobjectivesofthepresentstudyweretoexaminethespatialpatternsofswarddrymatter(DM)andnitrogen(N)yieldsinagrasssilagefieldatfirst,second,andthirdcutsovera3-yearperiod;quantifytheirtemporalstabilitieswithtemporalstabilitymaps;andassessthepotentialforsite-specificmanagementineachpasture-growingperiodusingclassifiedmanagementmaps.Atcut1,thespatialpatternsofDMandNyieldsprovedtobewelldefinedandtemporallystableandwerelikelytobeduetodifferencesinthenetNmineralizationratesacrossthefieldduringspring.Incontrast,atcut2,thepatternsofDMproductionwerepatchyandtemporallyunstable.Itwasconcludedthat,inprinciple,asimplesite-specificapproachtoNfertilizationwouldbepossibleinthisfieldduringspringatcut1.Atlaterharvests,therationaleforasite-specificapproachtofertilizermanagementwaslessclearwithlogisticsappearingtobemorecomplexandlessfeasible.

简介：Background:Understoryplantsrepresentsthelargestcomponentofbiodiversityinmostforestecosystemsandplaysakeyroleinforestfunctioning.Despitetheirimportance,theinfluenceofoverstory-layercompositiononunderstoryplantdiversityisrelativelypoorlyunderstoodwithindeciduous-evergreenbroadleavedmixedforests.Theaimofthisworkwastoevaluatehowtreeoverstory-layercompositioninfluencesonunderstory-layerdiversityinthreeforesttypes(monospecificdeciduousNothofaguspumilio(Np),monospecificevergreenNothofagusbetuloides(Nb),andmixedN.pumilio-N.betuloides(M)forests),comparingalsobetweentwogeographicallocations(coastandmountain)toestimatedifferencesatlandscapelevel.Results:Werecorded46plantspecies:4ferns,12monocots,and30dicots.Canopy-layercompositioninfluencestheherb-layerstructureanddiversityintwodifferentways:whilemixedforestshavegreatersimilaritytoevergreenforestsintheunderstorystructuralfeatures,deciduousandmixedweresimilarintermsofthespecificcompositionofplantassemblage.Deciduouspurestandswerethemostdiverse,meanwhileevergreenstandswereleastdiverse.Lackofexclusivespeciesofmixedforestcouldrepresentatransitionwhereevergreenanddeciduouscommunitiesmeetandintegrate.Moreover,landscapehasamajorinfluenceonthestructure,diversityandrichnessofunderstoryvegetationofpureandmixedforestslikelyassociatedtothemagnitudeandfrequencyofnaturaldisturbances,wheremountainforestnotonlyhadhighestherb-layerdiversitybutalsomoreexclusivespecies.Conclusions:OurstudysuggeststhatmixedNothofagusforestsupportscoexistenceofbothpuredeciduousandpureevergreenunderstoryplantspeciesanddifferentassemblagesincoastalandmountainsites.Maintainingthemixtureofcanopypatchtypeswithinmixedstandswillbeimportantforconservingthenaturalpatternsofunderstoryplantcompositioninsouthernbeechmixedforests.

简介：Exploringtheresponsedifferencesofleafphysiologyparameterstoenhancednitrogendepositionbetweensaplingsandtreesisvitalforpredictingthevariationsofterrestrialecosystemstructureandfunctionunderfutureglobalclimatechange.Inthisstudy,theecophysiologicalparametersofsaplingsandtreesofFraxinusmandshuricaRupr.weremeasuredatdifferentlevelsofnitrogenadditioninatemperateforest.Theresultsshowthatecophysiologicalparametersmaximumnetphotosyntheticrate(Pmax),apparentquantumefficiency(a),darkrespiration(Rd),lightsaturationpoint(Lsp),photosyntheticnitrogenuseefficiency(PNUE),specificleafarea(SLA)andstomatalconductanceundersaturatedlightintensity(Gsmax)werehigherinsaplingsthanintrees.ThesephysiologicalparametersandnotNleaf(leafnitrogencontent)ledtorelativelylowerPmaxandRdintrees.Forbothsaplingsandtrees,lowandmediannitrogenaddition(23and46kgha-1a-1)resultedinsignificantincreasesinPmax,Rd,Lsp,Chl,PNUE,SLAandGsmax.Theseparameterstendedtodeclineunderhighadditionsofnitrogen(69kgha-1a-1),whereasNleafwasalwaysenhancedwithincreasingnitrogen.VariationsinPmaxandRdwithincreasingnitrogenwereattributedtovariationsinthestronglyrelatedparametersof,Lsp,Chl,PNUE,SLAandGsmax.Overall,theresponsesensitivityofphysiologicalparameterstoenhancednitrogenlevelswaslowerintreescomparedwithsaplings.

简介：Background:Thelargepotentialofthesoilorganiccarbon(SOC)pooltosequesterCO2fromtheatmospherecouldgreatlyamelioratetheeffectoffutureclimatechange.However,thequantityofcarbonstoredinterrestrialsoilslargelydependsuponthemagnitudeofSOCmineralization.SOCmineralizationconstitutesanimportantpartofthecarboncycle,andisdrivenbymanybiophysicalvariables,suchastemperatureandmoisture.Methods:Soilsamplesofapineforest,anoakforest,andapineandoakmixedforestwereincubatedfor387daysunderconditionswithsixtemperaturesettings(5°C,10°C,15°C,20°C,25°C,30°C)andthreelevelsofsoilmoisturecontent(SMC,30%,60%,90%).TheinstantaneousrateofmineralizedSOCwasperiodicallyandautomaticallymeasuredusingaLi-CorCO2analyzer.BasedonthemeasuredamountofmineralizedSOC,carbonfractionswereestimatedseparatelyviafirst-orderkineticone-andtwo-compartmentmodels.Results:Duringthe387dayincubationexperiment,accumulativemineralizedcarbonrangedfrom22.89mgcarbon(C)·g-1SOCat30°Cand30%SMCforthemixedforestto109.20mgC·g-1SOCat15°Cand90%SMCfortheoakforest.Mineralizedrecalcitrantcarbonvariedfrom18.48mgC·g-1SOCat30°Cand30%SMCforthemixedforestto104.98mgC·g-1SOCat15°Cand90%SMCfortheoakforest,andcontributedatleast80%tototalmineralizedcarbon.Conclusions:Basedontheresultsofthisexperiment,thesoilorganicmatterofthepurebroadleavedforestismorevulnerabletosoilmicrobialdegradationinnorthernChina;mostoftheamountofthemineralizedSOCderivedfromtherecalcitrantcarbonpool.Labilecarbonfractionconstitutesonaverage0.4%ofSOCacrossthethreeforesttypesandwasrapidlydigestedbysoilmicrobesintheearlyincubationstage.SOCmineralizationmarkedlyincreasedwithsoilmoisturecontent,andcorrelatedparabolicallytotemperaturewiththehighestvalueat15°C.Nosignificantinteractionwasdetectedamongthese

简介：土壤腐殖的碳是土壤的一个重要部件在陆上的生态系统的器官的碳(SOC)。然而，到日期的学习都没调查它的地理模式和在大规模影响它的主要因素，尽管它为在土壤C存储和周转上探索气候变化的影响是批评的。我们测量了SOC的层次，腐殖的酸碳(HAC)，fulvic酸碳(FAC)，humin碳(HUC)，并且在沿着3800-km的九个典型森林里的0-10厘米土壤层的可引出的腐植质碳(HEC)东方中国(NSTEC)的纵贯的横断阐明土壤的纬度的模式腐殖的碳部分和他们的主要影响因素。SOC，HAC，FAC，HUC，和HEC与增加纬度增加了(所有P<0.001)，并且展出了一个一般趋势热带<副热带<适度。到SOC的腐殖的C部分的比率是9.48%-12.27%(HAC)，20.68%-29.31%(FAC)，和59.37%-61.38%(HUC)。气候，土壤质地，和土壤微生物联合在SOC，HAC，FAC，HEC，和HUC解释了超过90%纬度的变化，并且交互效果是重要的。这些调查结果阐明纬度的模式在大规模在森林里玷污腐殖的C部分，并且可以改进土壤C周转和存储的模型。

简介：Background:Treelinedynamicshaveinevitableimpactsontheforesttreelinestructureandcomposition.ThepresentresearchsoughttoestimatetreelinemovementandstructuralshiftsinresponsetorecentwarminginCehennemdere,Turkey.Afterimplementinganatmosphericcorrection,thegeo-shiftingofimageswasperformedtomatchimagestogetherforaperpixeltrendanalysis.WedevelopedanewapproachbasedontheNDVI,LST(landsurfacetemperature)data,airtemperaturedata,andforeststandmapsfora43-yearperiod.Theforesttreelineborderwasmappedontheforeststandmapsfor1970,1992,2002,and2013toidentifyshiftsinthetreelinealtitudes,andthenprofilestatisticswerecalculatedforeachperiod.Twentysampleplots(10×10pixels)wereselectedtoestimatetheNDVIandLSTshiftsacrosstheforesttimberlineusingper-pixeltrendanalysisandnon-parametricSpearman’scorrelationanalysis.Inaddition,thespatialandtemporalshiftsintreelinetreespecieswerecomputedwithintheselectedplotsforfourtimeperiodsontheforeststandmapstodeterminethepioneertreespecies.Results:Astatisticallysignificantincreasingtrendinallclimatevariableswasobserved,withthehighestslopeinthemonthlyaveragemeanJulytemperature(tau=0.62,ρ<0.00).Theresultantforeststandmapsshowedageographicalexpansionofthetreelineinboththehighestaltitudes(22m–45m)andthelowestaltitudes(20m–105m)from1970to2013.TheperpixeltrendanalysisindicatedanincreasingtrendintheNDVIandLSTvalueswithintheselectedplots.Moreover,increasesintheLSTwerehighlycorrelatedwithincreasesintheNDVIbetween1984and2017(r=0.75,ρ<0.05).CedruslibaniandJuniperuscommunisapp.weretwopioneertreespeciesthatexpandedandgrewconsistentlyonopenlands,primarilyonrocksandsoil-coveredareas,from1970to2013.Conclusion:Thepresentstudyilustratedthatforesttreelinedynamicsandtreelinestructuralchangescanbedetectedusingtwodata

简介：Elevatedatmosphericnitrogen(N)depositionhasbeendetectedinmanyregionsofChina,butitseffectsonsoilNtransformationintemperateforestecosystemsarenotwellknown.WethereforesimulatedNdepositionwithfourlevelsofNadditionrate(N0,N30,N60,andN120)for6yearsinanold-growthtemperateforestinXiaoxing’anMountainsinNortheasternChina.WemeasuredgrossNtransformationratesinthelaboratoryusing15NtracingtechnologytoexploretheeffectsofNdepositiononsoilgrossNtransformationstakingadvantageofNdepositionsoils.NosignificantdifferencesingrosssoilNtransformationrateswereobservedafter6yearsofNdepositionwithvariouslevelsofNadditionrate.ForallNdepositionsoils,thegrossNH4+immobilizationrateswereconsistentlylowerthanthegrossNmineralizationrates,leadingtonetNmineralization.Nitrate(NO3-)wasprimarilyproducedviaoxidationofNH4+(i.e.,autotrophicnitrification),whereasoxidationoforganicN(i.e.,heterotrophicnitrification)wasnegligible.Differencesbetweenthequantityofammonia-oxidizingbacteriaandammonia-oxidizingarchaeawerenotsignificantforanytreatment,whichlikelyexplainsthelackofasignificanteffectongrossnitrificationrates.GrossnitrificationratesweremuchhigherthanthetotalNO3-consumptionrates,resultinginabuild-upofNO3-,whichhighlightsthehighriskofNlossesviaNO3-leachingorgaseousNemissionsfromsoils.ThisresponseisoppositethatoftypicalN-limitedtemperateforestssufferingfromNdeposition,suggestingthattheinvestigatedold-growthtemperateforestecosystemislikelytoapproachNsaturation.

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简介：Decompositiondynamicswerecomparedamonggreentreeleaves,partiallydecomposedtreeleaflitter(i.e.,decayedtreeleaflitteronforestfloor)andamixtureofthetwoinawarmtemperateforestecosystemincentralChinatotesttheinfluenceoflitterchemicalqualityonthedegreeofdecomposition.Thestudywasconductedinsituattwocontrastingforestsites,anoakforestdominatedbyQuercusalienavar.acuteserrataMaxim.,andamixedpineandoakforestdominatedbyPinusarmandiiFranch.andQ.alienavar.acuteserrata.Wefoundmarkeddifferencesintherateofdecompositionamonglittertypesatbothforestsites;thelitterdecompositionconstant,k,wasabout39%greaterattheoakforestsiteandmorethan70%greateratthepine-oakforestsite,forgreenleavesthanforpartiallydecomposedleaflitter.Thedecompositiondynamicsandtemporalchangesinlitterchemistryofthethreelittertypesalsogreatlydifferedbetweenthetwoforestsites.Atbothforestsites,thehigherrateofdecompositionforthegreenleaveswasassociatedwithahighernitrogen(N)contentandlowercarbontoNratio(C/N)andacid-unhydrolyzableresiduetoNratio(AUR/N).Wedidnotfindanynonadditiveeffectswhenmixinggreenleavesandpartiallydecomposedleaflitter.Ourfindingssupportthecontentionthatlitterchemicalqualityisoneofthemostimportantdeterminantsoflitterdecompositioninforestecosystemsatthelocalorregionalscale,buttheeffectoflitterchemicalqualityondecompositiondiffersbetweenthecontrastingforesttypesandmayvarywiththestageofdecomposition.