黑龍江省穆棱東北紅豆杉天然種群結(jié)構(gòu)及年齡結(jié)構(gòu)

黑龍江省穆棱東北紅豆杉天然種群結(jié)構(gòu)及年齡結(jié)構(gòu)

u3000tectory一—Introductiontaxuscuspidatasieb。etzoci，so-callye，主要是風(fēng)寒地帶的溫帶，以及卡桑特的中國北部。它是一個由潘基文一帶統(tǒng)治的國家公園，其自然特征是緩慢而艱難的。這是第一階段，它是國家公園的主要區(qū)域，位于中國。正下方的自然恢復(fù)是遺跡。Yewlivesdispersedly,growsslowly,likesciophilicandcoldwethabitat,anditsannualgrowthincrementisrelativelylowerUptodate,manystudieshavebeencarriedoutonyewspeciesTheymostlyfocusedonitstissueculturetechnique(Haoetal2004;Wangetal.2002;Li2001;Gaoetal.1994;Chenetal2000),theisolationandextractionoftaxol,assayoftaxolconten(Yanetal.1994;Russinetal.1995;Yuanetal.2002;Shietal2003)andplantingtechnique,etc.(Wuetal.1996;Cuietal2003;Gaoetal.2003;Wenetal.2003).Reportonpopulationecologyofyew,however,isless.Inthisstudyweanalyzedthestructuralcharacters,distributionpatternsandsiteconditionsofyewandexplorethereasonswhyyewtendstobeendangeredspecies,soastoprovidesignificantreferenceforefficientprotectionandapplicationofyewresources.inraftasocietrautv...3.3日起算戰(zhàn)與5-5-5-5deg相對分子5,.........................................................5.5.ThisstudyisconductedintheShuangningandtheToudaogouforestfarmsofMulingForestryBureau(N19°50′-44°06′E110°38′–130°04′),HeilongjiangProvince,China,andoutsideNatureReserveofyew(Fig.1).EightcompartmentsofShuangningForestFarmandFourcompartmentsoftheToudaogouForestFarmarechosenasstudyareas.Thealtitudesofstudyareasisinrangeof680–731ma.s.l..Exposureisnortheastwithaslopeofabout15–45degrees(average18degrees).TheclimateofMulingareaistypicalcontinentmonsoon.Thefree-frostperiodisabout110days,annualmeanprecipitation440–510mm,annualaveragetemperature-2℃,andtheannualaccumulatedtemperatureabove5℃is1736.7℃.Yewismainlydistributedunderthemainstoreyofnaturalmixedforestofconiferandbroadleafontheupperandmiddlepartsoftheshadyslope,withacanopydensityof0.6-0.7.Thesoiltypeisthemountainousdarkbrownforestsoil.ThemainedificatosareAbiesnephrolepis(Trautv.)Maxim.),PiceakoraiensisNakai.,AbiesholophyllaMaxim,andthemaindominantspeciesarePinuskoraiensisSieb.EtZucc,BetulacosataTrautv,AcermonoMaxim.,TiliaamurensisRupr.,BetulaplatyphyllaSuk.,andtheshrubsincludeCorylusheterophyllaFish.exTrautv.,EquisetumhyemaleL.,Deyeuxiaangustifolia(Kom.)(Changetal.).u3000服刑人員sraftThree(male,female,andyoung)typicalsampleplots(20m×20m)wereseparatelysetupinthesitesinApril,2005.Thedistributionofyewanditscompanyspecieswereinvestigated(Fig.2).Thediameteratbreastheight,height,crowndiameterandnumberofyewtreeswereinvestigated(Fig.3-5).ThesiteconditionsweredeterminedusingspectrumSC-900,spectrumTDR-300,IQ-150,spectrumwatchdog,andotherinstruments.u3000si阿反應(yīng)a.refigfig.8AnalysisofpopulationstructureofwildyewInthemaleyewplot(Fig2A),onlyonebearingmaleyewwasfound.ItsDBHwas84cm(Fig3A)andheightwasmorethan15m(Fig3B)overthesecondmainstorey.Exceptforveryfewcompanionsandshrubs,noanyyoungtreeandseedlingofyewwerefound.Theresultmeansthatyewreproductionbyseedsmainly(Zhouetal.2004).Inthefemaleyewplot(Fig2B),thereweremanyfemaleyewsaccompanyingwithhigheredificatoanddominantspecies.TheDBHoffemaleyewwasinrangefrom40cmto60cm(Fig4A)andtheaverageheightwasabout15m(Fig4B).Thecrownoffemaleyewwaslargerthanthoseofotherspecies(Fig4C).Ofthesefemaleyewtrees,only3treeswereadult,therestsweretheyoungtrees(Fig.4D).Thisinvestigationresultindicatesthattheseedsofthebearingfemaleyewhavestrongpropagatingability,whichhelpstomaintainthepopulationstabilityofyew.Intheyoungyewplot(Fig2C),theyoungtreesofyewandtheircompanionspresentedanuniformitydistribution.Eighteenyoungtreesandseedlingofyewweresurveyed(Fig.5),accountingfor30%ofthetotaltreenumberintheplot,andtheymainlydistributedintheshadeenvironment.ShadeenvironmentcanpromotegrowthofyoungyewAnalysisofsiteconditionofwildyewMulingForestBureauisacentralizeddistributionareaofwildyew,andthesiteconditionhereissuitabletothecuttingpropagationofyew.Toexploremoresuitablesiteofyewpropagation,wesurveyedthesoilconditionsofmale,femaleandyoungyewsites.Resultsshowedthatthesoilmoisturecontentsofthethreeyewsiteswererelativehigh(Table1),61.4%formalesamplesite,43.6%forfemalesite,and47.3%foryoungyewsite,belongingtothetypicalmoistsoil.Thus,weinferthatduringthespring,themoisthabitatisbeneficialtothecuttingofyew.ThepHmeasurementshowedthatthesoilsofthethreesamplesitestendtobeacidic,inrangeof4–6.Theacidicsoilofyewsitesmayattributetothedistributionoftheconiferspecies.Thesoildensitywasobviouslydifferentindifferentdepthsofthesamplesites.Thesurfacesoilinthefemalesamplesitewasfloppyandratherthick(about5cm)andthatofthemaleyewsamplesitewasabout2.5cm.Comparatively,thesoiloftheyoungyewsamplesitewassolid(Table1).Hence,accordingtothedistributionandthenumberofyew,wecanconcludethatthesoilwithhighermoistureandacidityissuitableforgrowthofyew.Analysisofpopulationage-structureofyewTheaverageDBHoftheadultyewsinthesamplesiteswasmorethan50cmandtheaverageheightwasabove15m.Thenumberofadultyewwasquiteless,meantime,thetrunksoftheagedtreeswereoftenhollow.DBHofyoungyewwaslessthan5cm,andtheheightwasbelow3m,butthenumberwasmore(atleast20plants)(Fig.5).Thebranchesoftheyoungyewwereoftengnawedbywildlife,whichalsoaffectedthegrowthoftheyoungtrees.Yewwasnotthemainbodyinmainstoreyofstandanddidnotdistributeinsuccessionlayer.Onlyyoungyewshadagroupdistributioninregenerationlayer.Suchadistributionpatternofyewindicatedthatpopulationstructureisoneofreasonsleadingtoitspopulationdecline.Inourinvestigation,noyewindividualwithaDBHfrom5cmto50cmwasfound.Thisismainlyduetoexcessfellinga