1.51.51.51.51.5Life

Scienceschool,Fujianagricultureandforestryuniversity,Fuzhou,350002;Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002;Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002;Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002;Tianbaoyannationalnaturereserve,Yong'an,366032;Tianbaoyannationalnaturereserve,Yong'an,366032;LifeScienceschool,Fujianagricultureandforestryuniversity,Fuzhou,350002;Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002;Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002福建农林大学生命科学学院,福州,350002;福建农林大学林学院,福州,350002;福建农林大学林学院,福州,350002;福建农林大学林学院,福州,350002;永安天宝岩国家级自然保护区,福建永安,366032;永安天宝岩国家级自然保护区,福建永安,366032;福建农林大学生命科学学院,福州,350002;福建农林大学林学院,福州,350002;福建农林大学林学院,福州,350002350002;350002;;;;;13205008661;13328641118;;;;;13805017217;13328641118;;;;;福建农林大学林学院;福建农林大学林学院;;;;;youhuiming@126.
com;fjhdj1009@126.
com;xiaojuan24@yahoo.
com.
cn;yaljs@126.
com;cct5559@163.
com;youweibin@163.
com;527763357@qq.
comYOUHuiming(1984-),female,Ph.
Dcandidate,mainresearch:forestecology;HEDongjin(1969-),male,professor,mainresearch:forestecologyandlandscapeecology;;;;;游惠明;何东进;何小娟;刘进山;蔡昌棠;游巍斌;肖石红YOUHuiming;HEDongjin;HEXiaojuan;LIUJinshan;CAIChangtang;YOUWeibin;XIAOShihong何东进Specializedresearchfundforthedoctoralprogramofhighereducation(No.
20103515110005),NationalnaturalsciencefoundationofChina(No.
30870435)1.
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PlantEcology,2005,179:133~147|1|游惠明|YOUHuiming|福建农林大学生命科学学院,福州,350002;福建农林大学林学院,福州,350002|LifeScienceschool,Fujianagricultureandforestryuniversity,Fuzhou,350002;Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002|YOUHuiming(1984-),female,Ph.
Dcandidate,mainresearch:forestecology|福建农林大学林学院|350002|youhuiming@126.
com|13805017217|13205008661*|2|何东进|HEDongjin|福建农林大学林学院,福州,350002|Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002|HEDongjin(1969-),male,professor,mainresearch:forestecologyandlandscapeecology|福建农林大学林学院|350002|fjhdj1009@126.
com|13328641118|13328641118|3|何小娟|HEXiaojuan|福建农林大学林学院,福州,350002|Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002||||xiaojuan24@yahoo.
com.
cn|||4|刘进山|LIUJinshan|永安天宝岩国家级自然保护区,福建永安,366032|Tianbaoyannationalnaturereserve,Yong'an,366032||||yaljs@126.
com|||5|蔡昌棠|CAIChangtang|永安天宝岩国家级自然保护区,福建永安,366032|Tianbaoyannationalnaturereserve,Yong'an,366032||||cct5559@163.
com|||6|游巍斌|YOUWeibin|福建农林大学生命科学学院,福州,350002;福建农林大学林学院,福州,350002|LifeScienceschool,Fujianagricultureandforestryuniversity,Fuzhou,350002;Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002||||youweibin@163.
com|||7|肖石红|XIAOShihong|福建农林大学林学院,福州,350002|Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002||||527763357@qq.
com||天宝岩2种典型森林类型粗死木质残体空间分布格局研究|SpatialdistributionpatternofcoarsewoodydebrisintwotypicalforesttypesinTianbaoyannationalnaturereserve|Specializedresearchfundforthedoctoralprogramofhighereducation(No.
20103515110005),NationalnaturalsciencefoundationofChina(No.
30870435)SpatialdistributionpatternofcoarsewoodydebrisintwotypicalforesttypesinTianbaoyannationalnaturereserve#YOUHuiming1,2,HEDongjin2,HEXiaojuan2,LIUJinshan3,CAIChangtang3,YOUWeibin1,2,XIAOShihong2**(1.
LifeScienceschool,Fujianagricultureandforestryuniversity,Fuzhou,350002;2.
Forestryschool,Fujianagricultureandforestryuniversity,Fuzhou,350002;3.
Tianbaoyannationalnaturereserve,Yong'an,366032)Abstract:ThespatialdistributionpatternofcoarsewoodydebrisoftwotypicalforestecosystemswasconductedwithTaylor'spowerlaw,Iwao'sdistributionfunction,andsevenaggregationindexesinTianbaoyanNationalNatureReserve.
Theresultsshowedthat:1)thespatialdistributionpatternofCWDwereaggregated,andtheaggregationintensitydeclinedwiththescaleincreased;2)Comparedwithnaturaldisturbance,theaggregationintensityoflogsandsnagswereincreasedbyhumandisturbance;3)ItwastestedbyBlackith'smethod,thespatialdistributionpatternofCWDtendtobesusceptiblebytheexternalenvironmentconditioninsmall-scale.
ThespatialdistributionpatternofCWDwasformedbylong-terminteractionbetweennaturalenvironmentandexternaldisturbance.
Tosomeextent,basedontheseresults,wewilldirectlyacquaintourselveswiththeforestdeathpatternsinthepopulationdevelopment,thenrevealhowtheexternaldisturbance,environmentalheterogeneityandindividualbiologicalfeaturesinfluencethepopulationdynamics,thusprovidetheoreticalbasisforpredictingpopulationdynamics.
Keywords:coarsewoodydebris(CWD);typicalforestecosystems;spatialdistributionpatternIntroductionThespatialandtemporaldistributionofplantpopulationdynamicsanditsinfluencingfactorsareimportantpartsinstudyingpopulationecology,whileanalysisofpopulationspatialpatternsisthemajorapproachinstudyingpopulationcharacteristics,populationinteractionsandtherelationshipbetweenthepopulationandtheenvironment[1].
Differentspatialdistributionpatternsreflectthepopulation'sstatusofuseofnaturalresources.
Thisishelpfulnotonlyindisclosingthespatialandstructuralfeaturesofthepopulationdistribution,butalsooffar-reachingsignificanceinpredictingthepopulationdynamicsandclarifyingitssuccessionlaws,ecologicalfeaturesandrenewalstrategy.
Inthestudyofpopulationstructuresandpatterns,mostofthecurrentresearchfocusesonthelivingtrees[1~5],whilethedeadwoodisrarelyinvolved[6~8].
Asanimportantcomponentoftheforestecosystem[9],thedeadwood'sspatialdistributionpatternsplayakeyroleinrevealingtheforestpopulationdynamics.
Externalinterferenceandthecoarsewoodydebris(CWD)leftbehindbydeadtrees,widelyexistintheforestecosystem,andparticipateintheforestmaterialcirculationandenergyflow[10~11].
CurrentresearchontheCWDcentersaroundsuchareaslikeitsquantitativefeatures[12],decomposition[13],respiration[14],nutrientdynamics[15~17],ecologicalfunctions[18~21],thespatialpatternsisseldomreferred[6~8].
However,thispaperattemptstointroducetheaggregationindexmethod,andselectstheTsugaLongibracteataforesttypewhichwaslessaffectedbyinterference,andCrytomeriafortuneiforesttypewhichwasseriouslycuttingattheTianbaoyanNationalNatureReserve,asthestudyobject.
Byemployingtheaggregationindex,theinteractionlawbetweentheCWD'sspatialdistributionfeaturesandtheenvironmentundertheinfluenceofdifferentdisturbancewasanalysed,thusitentailsabetterunderstandingoftheforestpopulationdynamicswithaviewtoprovideatheoreticalframeworkfortheprotectionandmanagementoftheforestecosystem.
StudyareaTianbaoyanNationalNatureReserveliesintheintersectionofXiyang,Shangping,andQingshuiviliageinYong'an,FujianProvince.
Eastlongitude117°28′3″~117°35′28″,northlatitude25°50′51″~26°1′20″.
Thereservecoversanareaof11015.
38hm2,anditscoreis36kmawayfromYong'ancity.
TianbaoyanwasformallyauthorizedasprovincialnaturereservebyFujianpeople'sgovernmentinDecember,1988,andpromotedasnationalreservebystatecouncilinJune,2003.
TianbaoyanNationalNatureReserveisapartofMountDaiyun,andisamiddle–to-lowlandformhill,anditshighest&lowestelevationis1604.
6mand580mrespectively.
Itischaracterizedbymid-subtropicaloceanicmonsoonclimaticregion,withtheannualaveragetemperaturebeing15℃.
TheaveragetemperatureinJanuaryis5℃and23℃inJuly.
Theextremehighandlowtemperaturesis40℃and-11℃inturn.
Theactiveaccumulatedtemperaturethatit10℃oroveraddsup4500~5800℃,andfrostlessperiodis290d.
Theannualaverageprecipitationis2039mm,centeringaroundMaytoSeptember.
Theannualaveragerelativehumidityisover80%.
Thereservehasdistinctiveseasons,andgoodconditionsinsunlight,heatandwater,besides,itsclimateiswarmandmoist.
TheDevonian&Jurassicsedimentaryrocks,andthegranitesareexposedinthereserve.
Theredsoil,thezonalsoil,evolvesfromgranitesandsandstonebyweathering,andisdistributedbelowtheelevationof800m.
Itisuplandyellowishredsoilbetweentheelevationof800~1350m,anduplandyellowsoilbelow1350m.
Sometopicalintermontanebasincandeveloppeatysoil.
Thesoillayerinmostareasisrelativelythin,butthelayersinRhododendronsimiarumforestsandTsugalongibracteataforestsarerelativelythickandcanamountto1morover.
Thethicknessinhumushorizonisabout20cm,and5~20cminlitterlayer,inaddition,thetextureofsurfacesoilisacidlome.
MethodsPlotsettingandinvestigationTwotypesofthetypicalmid-subtropicalforestecosystemswereselectedinTianbaoyanNationalNatureReserve(Tab.
1),andaccordingtotheelevationfactor,twoplotswiththeareaof20m*30mweresetupateachelevationwithineachtypeoftheforests,sotherewere12plotsintotal.
Thentheplotswereinvestigatedwiththemethodofcontiguous-gridquadrats,andthefactorslikecommunitytype,elevation,gradientandslopepositionweremeasuredineachsampleplot.
Inaddition,thecoarsewoodydebris(CWD)withintheplots,namely,thesnags,fallentrees,bigbranchesandstumpswiththediameteratbiggerendmorethan2.
5cmandlengthover1.
0m,weremeasuredonebyone,andtheircorrespondingorderandtreespeciesweresetdown.
Moreover,theirinputways(snag,breakageattrunkbase,breakageontrunk,uprootingandstump),heightorlength,DBH(diameteratbreastheight),thediameteratbiggerend,diameteratthesmallerendanddiameteratthemiddleweremeasuredaswell.
Decaystatewascategorizedusingafive-classsystembasedonvisualandphysicalcharacteristicsfollowingYan(2005)[22],andwererepresentedasⅠrespectively.
Tab.
1ThesettingofplotsPlotVegetationtypeCanopycoverage(%)Elevation(m)Gradient(°)SlopeaspectPlotarea(m2)1Tsugalongibracteataforests70151130SE15°12002Rhododendronsimiarum-Tsugalongibracteataforests8513245NW30°12003Rhododendronsimiarum-Tsugalongibracteataforests98121820SE5°12004Crytomeriafortuneiforests90154717NE20°12005Crytomeriafortuneiforests64110624NE33°12006Crytomeriafortuneiforests6199225SW20°1200Studymethodsofspatialdistribution(Chenetal,1999)①Diffusioncoefficient(Thereinto,,;issamplecapacity;isthetotalNo.
ofthepopulation;istheNo.
ofthesamplingunit(thesameinthefollowingequations).
WhenC=1orC~[1-,1+],itisrandomdistribution;whenC>1,aggregateddistribution;whenC0,aggregateddistribution;when,it'saggregateddistribution;when1,aggregateddistribution;when0,aggregateddistribution;when=0,randomdistribution;andtheintensityofaggregatedincreasedwithincreasingCa.
⑥NegativebinomialKvalue,K=,theKvaluedeclinewiththeaggregationintensityincreased.
⑦BlackithAggregationAverage(λ)(Qiuetal,2008)6)KisthenegativebinomialdistributionKvalue,isthedistributionvalueof,whenthefreedegreeis2K.
2Kisusuallyadecimal,andshouldbecalculatedaccordingtopercentage.
Whenλ0,thebasiccomponentofdistributionisindividualgroup;whenα1orα>0,β≥1,thepatternofthepopulationisaggregateddistribution;Butinpracticalapplication,thereexistsadegreeofdeviationbetweenαandβ,sothepossibilityofbeing0and1iszero.
Thedegreeofdeviationofrandomdistributionistestedwiththefollowingequation(Chenetal,1999),namely:(8)If≥,thenthepopulationdisplaysaggregateddistribution,otherwise,randomdistribution.
(9)Thereinto,isthesampling&statisticalfactor;istheaggregationindex,andcanreflectspecificattributesofthespecies;When=0,itisuniformdistribution;when>1,aggregateddistribution;when=1,randomdistribution.
ResultsanddiscussionSpatialdistributiontypesAggregationIndexAccordingtothecriteriaofeachaggregationindicator,itisindicatedfromTable2that1)whenm*>m,I>0,m*/>1,Ca>0,C>1,02,duetothedistributionoftheTsugaLongibracteataforestismainlymadeupofmatureandover-matureforest,theCWD'sspatialdistributionpatternisinfluencedbytheenvironmentalheterogeneityandtheseed'sdistributioncharacteristics[1].
Therefore,itisconcludedthatitissomehowviabletoapplytheBlackithpopulationmeanλtoinvestigatethereasonforCWD'saggregation.
ThevariousCWD'saggregationindicatorattheCrytomeriafortuneforestshownintable3.
Accordingtothecriteriaofeachaggregationindicator,Table3showsthat1)whenm*>m,I>0,m*/>1,Ca>0,C>1,01,theCWD'sdistributionpatternspresenttheaggregationtendencyTab.
4SimulatedresultsfromIwaoequationfortwodifferenttypesofforestsVegetationtypeIwaoequationEquationRelatedcoefficientsFTL25m2m1*=-0.
441+1.
2290.
9029.
98750m2m1*=-0.
177+1.
0940.
96719.
408100m2m1*=-0.
294+1.
0600.
996106.
04CF25m2m2*=-2.
851+2.
0750.
9355.
872150m2m2*=-1.
318+1.
3430.
98721.
094100m2m2*=-2.
818+1.
3190.
995273.
62TL:Tsugalongibracteataforests;CF:CrytomeriafortuneiforestsTaylorexponentialequationTab.
5SimulatedresultsfromTaylorexponentialequationforthreedifferenttypesofforestsVegetationtypeScaleTaylorexponentialequationEquationRelatedcoefficientsTL25m2S12=0.
3890.
85250m2S12=0.
3300.
987100m2S12=0.
1550.
995CF25m2S22=0.
3700.
88650m2S12=0.
2710.
937100m2S12=0.
0080.
973TL:Tsugalongibracteataforests;CF:Crytomeriafortuneiforestswhichisconsistentwiththeresultsbyusingtheaggregationindexmethod.
Underdifferentscales,withinthesameforesttypes,theβvaluedecreaseswiththeexpansionofscale,whichisinstrictconformitywithLiuetal(2010)[8].
Thetwotypes'relatedcoefficientsarelargerthan0.
90,indicatingthatthereisahighdegreeoffitnessinregressionmodels,andthedegreeoffitnessincreaseswiththeexpansionofscales.
When(8)isadoptedtotesttherandomdistributiondeviationwithinthetwoforesttypes,itshowsthatunderthescaleof25m2,theTsugalongibracteataforest'sdistributionvalueF=9.
987>F0.
05(2,4)=6.
944,thusitsspatialdistributionpatternisaggregateddistribution.
However,theCrytomeriafortuneiforest'sdistributionvalueF=5.
872F0.
05(2,4)=6.
944,weinferthatitsspatialdistributionpatternisaggregateddistribution.
Theexponent-relatedregressionequation(Tab.
5)ofthefitvariance(S2)andtheaverage()aretestedbyTaylor's(1965)exponentiallaw,andtheresultsindicatethattherelatedcoefficientsriseupaccordingtothescaleexpansion,andthatthedegreeoffitintheregressionmodelincreaseswiththeexpansionofscales.
Underthethreekindsofresearchscale,thebvalueoftheCWDattheTsugalongibracteataforestandtheCrytomeriafortuneiforestinTaylor'smodelislargerthan1,whichshowsthatwithinthetwoforesttypestheCWD'sdistributionpatternsistheaggregatedones.
OptimalSamplingTab.
6ThetheoreticalsamplingnumbersunderdifferentpopulationdensitiesinTsugalongibracteataforestsAllowingerrorsMeandensity(Individuals/25m2)1234D=0.
179514237D=0.
22013109D=0.
39654Tab.
7ThetheoreticalsamplingnumbersunderdifferentpopulationdensitiesinCrytomeriafortuneiforestsAllowingerrorsMeandensity(Individuals/50m2)567891011121314D=0.
128293030313131323232D=0.
27778888888D=0.
33333333444AccordingtoIwao'sm*-regressionequationandtheoptimalsamplingformula,wecalculatetheCWD'soptimalnumberofsampling(tab.
6&7)underdifferentdensitiesandallowingerrorswithinthetwoforesttypes,whichwillprovidetheoreticalbasisfordeterminingtheCWD'ssamplingtechniques.
Duetothatunderthe25m2researchscaletheCWD'sdistributionattheCrytomeriafortuneiforestdoesnotconformtothem*-linearmodel,wechoosedifferentdensitiesunderthe50m2researchscaleforcalculatingtheoptimalsamplenumber.
TheCWD'soptimalsamplenumberreducesattheTsugalongibracteataforestiftheaveragedensityincreases(tab.
6),whichisinconsistencywithpreviousresearchers'findings[2,23].
Onthecontrary,theCWD'soptimalsamplenumberattheCrytomeriafortuneiforestisoppositetothatoftheTsugalongibracteataforest(tab.
7),maybebecausethatthehumanbeing'sdisturbancecausestheoptimalnumberofsamplestoincreasewiththeincreaseoftheaveragedensity,whilethepreviousresearchmostlystudiedtheundisturbednaturalpopulations[2,4,23].
Underthe25m2researchscaleandwiththeassistanceofthetable,wenoticethatthesamplenumberis144attheTsugalongibracteataforestwhichenablesthesamplenumbertomeettheaccuracyrequirement,thusitiscrediblethattheCWD'sdistributionmodelattheTsugalongibracteataforestisanaggregatedone.
Underthe50m2researchscaleandwiththeassistanceofthetable,wenoticethatthesamplenumberis72attheCrytomeriafortuneiforestwhichenablesthesamplenumbertomeettheaccuracyrequirement,thusitisalsocrediblethattheCWD'sdistributionmodelattheCrytomeriafortuneiforestisanaggregatedone.
ConclusionTheformationofthepopulations'distributionpatternsistheresultoflong-termmutualadaptationandinteractionbetweenthespeciesandtheenvironment.
Ontheonehand,itdependsonthespecies'ecologicalandbiologicalcharacteristicsandtheecologicalcompletionprocessesbetweenspecies.
Ontheotherhand,itiscloselyrelatedtothespecies'environmentandinterference[26~27].
TheCWD'saggregationdecreaseswiththeexpansionoftheresearchscale,theCWDisinclinedtoaggregateddistributionunderthesamllerresearchscale,butinclinedtorandomdistributionwhentheresearchscaleislargerthanacriticalscale[8].
TheCWDunderthespatialscaleinourstudyisaggregateddistributed,whichshowsthattherearestilllimitationsinourtraditionalresearchmethodofthespatialpatterncomparedwiththepointpattern.
ItisdifficulttovisuallyreflectthechangesoftheCWD'sdistributionpatternsunderdifferentresearchscales,especiallyforthedefiningofthecriticalscale.
Nevertheless,intheabsenceofindividualcoordinates,usingtheaggregationindicatorscanserveasabetterandmoreconvenientmethodforanalyzingthepopulations'spatialdistribution.
Inthisspatialdistributionanalysis,weaddBlackith'spopulationaggregationmeanλtoinvestigatethereasonsofaggregation.
TheoutcomeshowsnotonlythatitissomehowfeasibletoadopttheindicatorstoanalyzetheCWD'sreasonofaggregateddistribution,butalsothatitwillremedythedefectsofsuchmethods,thereforeprovidesvalidinformationforinferringitsimpactfactors[28],andalsoprovidestheoreticalbasisforformulatingeffectiveforestmanagementandprotectionstrategies.
Thisstudyrevealsthatthesmall-scalestudyismoresusceptibletoreflecttheinfluenceoftheexternalenvironmentalheterogeneitytotheCWD'sspatialdistributionpatterns.
Italsorevealsthatcomparedwiththenaturaldisturbance,humandisturbancewillincreasetheaggregationofthelogsandsnagsattheforests.
TheresearchresultswillhelppeopleunderstandtheCWD'sspatialdistributionpatternsanditsinteractionwiththeexternalinterference,andprovidereliabletheoreticalbasisforpredictingthetendencyofpopulationdevelopment.
Thedeathoftheforesttreesisthenaturalresultofforestdevelopment,thedeadwoodisatypicalfeatureoftheforestecosystemdynamics(Luoetal,2004).
Thisstudy,takeingtheCWDastheobject,anddirectlyrevealingtheoccurrencelawofwooddeathduringthepopulationdevelopmentprocess,willhelpdisclosingtheimpactoftheexternalinterference,theenvironmentalheterogeneity,andindividualbiologicalfeaturesonthepopulationdynamicschange.
Itisalsoofgreatsignificanceinclarifyingthepopulation'ssuccessionlaw,ecologicalfeatures,anditsrenewalstrategy.
AcknowledgementsThisworkwasfundedbySpecializedResearchFundfortheDoctoralProgramofHigherEducation(No.
20103515110005)andNationalNaturalScienceFoundationofChina(No.
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福建农林大学生命科学学院,福州,350002;2.
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永安天宝岩国家级自然保护区,福建永安,366032)摘要:本文运用聚集度指标法对天宝岩国家级自然保护区内两种典型森林类型内的CWD的空间分布格局展开研究,结果表明:1)两种森林类型内CWD的空间分布呈聚集分布,且聚集强度随研究尺度的扩大而降低;2)人为砍伐干扰与自然干扰相比,会提高林分内倒木和枯立木聚集度;3)Blackith聚集均数(λ)表明小尺度研究范围能够更敏感地反映外界环境异质性对CWD空间分布格局的影响.
CWD的空间分布格局的形成是其与自然环境及外界干扰长期相互适应和相互作用的结果,某种程度上借助CWD的空间分布型可直接了解种群发展过程中林木死亡的发生规律,揭示外界干扰、环境异质性及个体生物学特性对种群动态变化的影响,为预测种群的动态过程提供理论依据.