长白山北坡主要建群树种群结构及重要值沿海拔梯度的变化

长白山北坡主要建群树种群结构及重要值沿海拔梯度的变化

Introduction1内省学习方程式内省和外省平台国际医学回收下的calciate数据处理软件中的used数据处理。import值由数据序列产生，这是跟踪s（wangetal.1996）：。影响的分析内插入布局棕榈叶投资intrograenvi治理/atironsoningblot.Plantcommunityisalong-termprocessoftheplantcomplexformationanddevelopmentinalong-historyprocess,anditisrelatedcloselytotheenvironments(Haoetal.2002).Plantcommunityiscomposedofdifferentplantpopulations,so,studyingplantpopulationsisoneofthebasesofplantcommunityecology(Dengetal.2000).Inaplantcommunity,thespeciesthatcontrolsenergyflowandthematerialcycleeffectivelyandhasobviousthemostapparenteffectsoncommunitycompositionandcommunityenvironmentformationiscalledthedominantspecies(Magurran1988).Eachdifferentlayerofcommunityhasowndominantspecies,andthedominantspeciesindominantlayerisedificator(Sunetal.1993).Commonlyabundanceandcoverageoftheedificatorisover80%(Wangetal.1996).ThereexistsanobviousenvironmentalgradientonthenorthslopeofChangbaiMountain,andspeciescompositionsvaryalongthealtitudegradient(Wangetal.1980;Chenetal.1964;Zhao1980).Thepresentresearchdealtwiththevariationsofpopulationstructureandimportantvalueofmainedificatorsalongtheelevationgradient,anditsresultscouldreflectthestatusandfunctionsoftheedificatorsintheplantcommunitiesandrevealthedistributionpatternsoftheedificatorsalongelevationgradients.Thestudywasconductedbetweenthealtitudesof700mto1900monnorthernslopeofChangbaiMountainwithahorizontaldistanceof40km.Theannualtemperatureintheareaofelevationof700maverages2.8°Canditbelongstothetypicalwarmtemperatezone.Attheelevationof1900m,theannualaveragetemperatureis-3.3°Canditbelongstothesub-alpineclimate(Chietal.1981;Zhangetal.1984).Alongtheelevationgradient,thereexistdifferentvegetationtypes:broad-leaved/Koreanpineforest(elevationlowerthan1100m),darkconiferousforest(from1100mto1800m),andsub-alpineBetulaermaniiforest(from1800mto2000m),(Wangetal.1980;Zhao1980).ClimatefactorsalongtheslopewereshowninTable1(Chietal.1981).Thesamplingplotsweresetbygradientpattern.Fromthealtitudesof700mto1900m,13plots(1024m2)of32m×32mwithanatintervalsof100minelevationwereset.Basiccharactersuchasaltitude,slopedegreeandcoverageoftheplotwasfirstinvestigated,andthenasketchoftheplotwasdrawn.Ineachplot,treespecies,diameteratbreastheight(DBH),incrementalstate(witheringornormal)andtreeheightweremeasured.Accordingtodiameterandheightoftrees,threegroups:overstorey(overstorey,DBH≥8cm),successionallayer(sapling,DBH<8cm),renewallayer(seedling,height<1.3m,noDBH)wereclassifiedwhere,RAimeansrelativeabundanceofspeciesi;RFimeansrelativefrequencyofspeciesi;RDimeansrelativedominanceofspeciesi;IQimeansindividualquantityofspeciesi;PQimeansplotquantityofspeciesi;BHAimeansbreastheightareaofspeciesi;andIVimeansimportantvalueofspeciesi.Fig.1showedpopulationstructuresofsomeedificatorsatdifferentelevations.FromFig.1,itwasknownthatsomeedificatorpopulationssuchasAbiesnephrolepisandPiceajezoensisvar.komaroviihadanormalpopulationdistributionofindividualquantityateachelevation,andespeciallyintheircoredistributionarea(1200-1700m),theirdistributionfrequenciesapproached100%.Therewerequiteabundantindividualsoftheseedificatorsinthemainforestlayer,successionlayer,andgenerationlayer,andthisshowedthattheyhadahealthydevelopmentalpopulationstructure.ForLarixolgensis,thereweremainlyoldbigtreesofamono-generation,andateachelevation,theyaccountedforacertainpercentageinthemainforestlayer,butinsuccessionlayerandregenerationlayer,therewerefewindividualsofLarixolgensis.ThisshowedthatLarixolgensiscouldnotregeneratenormallyatelevationof800-1800mandwasadecliningpopulation.Onlyinthecoredistributionareaunderanelevationof1200m,seedlingsofPinuskoraiensiswereabletogrowintothemainforestlayerandtheregenerationcouldberealized.Atelevationof1300-1400m,althoughtherewererelativelyabundantseedlings,theseedlingscouldnotgrowanddevelopnormallyintothemainforestlayer.Above1800m,therewerefewtreesandseedlingsofPinuskoraiensis.Betulaermaniiishigh-elevationspecies,butitsfrequencyandquantityinthecoredistributionareawerelowerthanthoseoutofthecoredistributionarea.OtheredificatorssuchasTiliaamurensis,Fraxinusmandshurica,andAcermonohadtheirhealthypopulationstructuresonlyunderanelevationof1000m.Theirregenerationquantitieswerenotlarge,butotherqualitieswerewell.Fig.2showsthevariationofimportantvaluesofmainspeciesalongtheelevationgradient.Fromanelevationof700m,theimportantvalueofAbiesnephrolepisgraduallyincreasedwithelevationincreasing,andreachedthemaximumvalueof30%atanelevationof1400m,andthenitbegantograduallydecrease.ImportantvalueofPiceajezoensisvar.komaroviiincreasedgraduallyfrom700mto1600m,too.AbiesnephrolepisandPiceajezoensisvar.komaroviiplayedimportantrolesinthewholeplantbelt,andatmostelevations,theirimportantvalueswereover20%.ImportantvaluesofPinuskoraiensisandAcermonohadasimilartrend,andincorrespondingcommunities,theirimportantvalueswereverysimilar,whichshowedthattheyhadsimilarecologicaladaptabilities.ImportantvaluesofQuercusmongolicaandTiliaamurensiswerefrom10%to20%atelevationsbelow1000m,andthisshowedthattheyhadhigherimportancevalue.Above1000m,theirimportantvalueswereverylow,andabove1200m,theirimportantvalueswerezero.Fraxinusmandshuricahadhighimportantvalueonlyat700m,andtheimportantvaluedescendedgraduallywithincreasingelevation,andwaszeroabove1100m.ImportantvalueofLarixolgensishadnoobviousvariationswithelevationchanging.Fromlowelevationtoforestline,importantvalueofLarixolgensiswasmostlyabout20%.ThisadequatelyshowedtheparticularityandstrongadaptabilityofLarixolgensis.Betulaermaniienteredintothemainforestlayerabove1500m.TheimportantvalueofLarixolgensisincreasedwithelevation,andreachedto80%atelevationof1800m.So,Betulaermaniiwastheonlyspeciesthatcouldformamono-dominantcommunity.AlthoughtherewerelotsofstudiesonplantcommunitiesonnorthernslopeofChangbaiMountain,therewerefewstudiesaboutthevariationsalongelevationgradientandconsideredthecommunitiessynthetically(Haoetal.2002).Inrecentyears,somerelativestudiesturnedtheirfocustothevariationsalongelevationgradient,andtheyhadimportanteffectsincompletingtherelativeresearches(Dengetal.2000;Haoetal.2002).Intheircoredistributionareas,mostoftheedificatorshadhealthypopulationstructureandcouldregeneratesmoothlyexceptLarixolgensis,buttheimportantvalueofLarixolgensishadnoobviousvariationswithelevationchanging,whichshowedthatLarixolgensishaditsownparticularityandstrongadaptability.Althoughthereexisteddifferentvegetationbeltsonno