The relationship of site conditions to the invading capability of Melaleuca Quinquenervia in Southwest Florida
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Title: The relationship of site conditions to the invading capability of Melaleuca Quinquenervia in Southwest Florida
Physical Description: x, 151 leaves. : illus. (some col.) ; 28 cm.
Language: English
Creator: Myers, Ronald Lewis, 1946-
Publication Date: 1975
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Subjects / Keywords: Melaleuca   ( lcsh )
Forest ecology   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis (M.A.)--University of Florida.
Bibliography: Bibliography: leaves 148-150.
Statement of Responsibility: by Ronald L. Myers.
General Note: Typescript.
General Note: Vita.
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THERELATIONSHIPOFSITECONDITIONSTOTHEINVADING CAPABILITY OFMELALEUCAOUINQUENERVIAIN FLORIDABYRONALDL. NYERS ATHESIS PRSSENTED TOTHE COUNCILOFTHEUNIVERSITYOFFLORIDAIN FULFILLME"IT OFTHE REQUIREt1ENTS FORTHEDEGREE OF i'lASTEROFSCIENCE UNIVERSITYOFFLORIDA 1975

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Thewriterwishestoexpresshisgratitudetohissupervisory cownattee, Dr.H.T.Odum,Dr.DanielB.Ward,andespeciallytoDr.JohnJ.Ewel,underwhosedirectionandencouragementthisstudywas ThewriterexpressesappreciationtotheNationalParkService,UnitedStatesDepartmentoftheInteriorforfundingthisprojectundercontract nuwber CXOOOl30057,EnergyModelsforPlanninginSouthFlorida,throughtheCenterforWetlands,UniversityofFlorida.SpecialthanksgototheRangerDivisionofEvergladesNationalParkfortheirlogisticalsupportandcontinuousencouragement.ii

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TABLEOFCONTENTSACKNOWLEDGEMENTSiiLISTOF TABLESvLISTOF FIGURESviiABSTRACTixINTRODUCTION.1CharacteristicsofMelaleuca4NativeRangeandDistribution8UsesofMelaleuca........."9IntroductionandSpreadof Melaleuca inSouthFlorida....11AreasBeingInvadedinLeeandCollierCounties...12Objectives..17PRELIMINARY MODELING.19 Procedure ....19Results..22SEED GERNINATION IN THE LABORATORY.....28Objectives.........28Procedure......................29Results.......................29HYDROPERIOD IN TP..EGREE;-iHOUSE..... .a_ 32Objectives32Procedure...............................'O..................33Results....................................37iii

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THE RESPONSEOFHELALEUCATO AN2\EROBIC SOIL CONDITIOnS ..44Objectives..........................................................................................................44Procedure.45Results45FIELDSTUDIES.48Objectives49Procedure.50Results.56siteDescriptions.56SeedingTrials85FieldPlantings..100SURVIVAL OF NATURALLY REGENERATED SEEDLINGS107Objectives.......107Procedure......107Results......108DISCUSSION..IIISeedGerminationandSeedlingSurvivalIIIMoistureRequirements111HydroperiodandwaterLevel114Fire.....116SiteSusceptibilitytoHelaleucaInvasion.122Qualitative Hodel' ..........131 Nanagernent Alternatives135FutureSpreadand EnvironnentalImpact 145LITERATURECITED...............................148BIOGRAPHICAL SKETCH.............................151iv

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LISTOFTABLES 1Estimatedvaluesandpotsettingsusedinthemodelsimulation............232 Daily total,andpercentgerminationfromsevenbatchesof300seedssubjectedtodifferentmoistureregimes.303Seedlinggrowthunderaeratedandanaerobicsoilconditions464Studyplotlocations,datesof andsitedescriptions..............5256Listofcommonplantsonthelongleaf pine flatwoodsite..............58Listofcommonplantsonthemixedhardwood--cypressforestsite......................................................................................................................647Dissolvedoxygenmeasurementstakenonfloodedstudysites...678Listofcommonplantsontheburnedmixedhardwood--cypressforestsite.........................69910111213Listofcommonplantsonthedwarfcypressforestsite..................72Listofcommonplantsonthewetprairiesite....................................76Listofcommonplantsonthematurecypressforestsite................79Listofcommonplantsonthemangrovesite..........................................83Listofcornmonplantsonthemixedhardwood--cypresssite............8714Resultsoffieldseedingsonthelongleafpineflatwoodsite....................................9015Resultsofthefieldseedingsonthemixedhardwood--cypressforestsite......................................9116Resultsofthefieldseedingsonthe burned mixedhardwood--cypressforestsite_..........._...9217Resultsofthefield see-dings onthe dharf forestsite.......................................................94v

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18Resultsofthefieldseedings onthe wetprairiesite..951920Resultsofthefieldseedings on the nature cypressforestsite......................Resultsofthefieldseedingsonthemangrovesite979821Resultsofthefieldseedingsonthedrainedcypressforestsite..........9922 ofnaturallyregeneratedMelaleucaseedlingsonthreeburnedsitesandtheresultsofseedingsonthesamesitescarriedoutlaterinthewetseason.109vi

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LISTOF FIGURF;S 1Melaleucainflorescenseandfruits.6 2Preliminarymodel....21345Simulation#1Simulation#2Simulation#3............................................................................................................................................................................................................................................................................................................2425276 Twotreatmentsinthehydroperiodvariationequipment347Diagramoftreatmentvariationexperimentschedulesinthegreenhousehydroperiod......................................................................................368Growthdifferencesinthehydroperiodvariationexperiments.399 Meanheightoftheseedlingsineachtreatmentafterthreeandsixmonths...................4010Averageshoot,root,andtotaldry Height ofseedlingsaftersixmonths.......................4211Mapof southHest Floridashowinglocationofstudysites5412Longleafpineflatwoodsite.....5713Monthlysoilmoisturechangesandlengthoffloodingonthelongleafpineflatwoodsite........5914Waterlevelchangesontheeightstudyplots.....6215Mixedhardwood--cypressforestsite..........6316Monthlysoil I!'tois"ture changesand l'2ngth offloodingonthemixed hard\"ood--cypress forestsite6517Burnedmixed forestsite6818Dwarfcypressforestsite7119 Nonthly soilmoisturechanges and1eilght offloodingonthe dwarf cypressforestsite ... .. .... .. ..................73vii

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20 1'1:ot prairiesite.......................................7521Monthlysoilmoisturechangesandlengthoffloodingonthewetprairiesite.............................7722Maturecypressforestsite..........8023Monthlysoilmoisturechangesandlengthoffloodingonthematurecypressforestsite...........8124Mangrovesite..........8425Drainedcypressforestsite.....8626Monthlysoilmoisturechangesandlengthoffloodingonthedrainedcypressforestsite....8827Seedlingsurvivaloneachstudyplotfromthefourplantingtrials.................10228Meanheightgrowthofseedlingswhichsurvivedeachplanting.................10329PlantedcypressandMelaleucaseedlingsonthedrainedcypressforestsite............................10630Drainedcypressstudysiteshowingdenseherbaceousgroundcover...................................11831Melaleucaseedlingsonanidealsiteforsuccessfulestablishment12332DenseMelaleucareproductioninadrainedandburnedcypressforest.......................12433AMelaleucastandinConservationArea3A.12734LargewoodyadventitiousroottypicalofthosefoundcommonlyonMelaleucagrowingoncontinuouslyfloodedsites...12835Qualitativecompetitionenergyflow diagram oftelaleuca--cypress13336BurnedstandofMelaleuca............................13737Melaleucastumpsproutssixmonths after acontrolcutting .... 14038Na-tureNelaleucaforestat Six-i:\ileCypress Strand,southeastofFortMyers_...........................143viii

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AbstractofThesisPresentedtotheGraduateCounciloftheUniversityofFloridainPartialFulfillmentoftheRequirementsfortheDegreeofMasterofScienceTHERELATIONSHIPOFSITECONDITIONSTOTHEINVADING CAPABILITY OFMELALEUCAQUINOUENERVIAINSOUTHWESTFLORIDA ByRonaldL.MyersMarch1975Chairman:JohnJ.MajorDepartment:EwelBotanyTheabilityoftheintroducedtreeMelaleucaquinquenervia(Cav.)BlaketoinvadedisturbedandundisturbedsitesinSouthwestFloridawasinvestigatedbyfieldexperimentsinvolvingseeding anc plantingtrialsatregularintervalsonavarietyofsites.Inconjunctionwiththesefieldstudies,greenhouseexperimentswereundertakentodeterminemoisturerequirementsforseedgermination,plusseedlinggrowthunderartificiallyinducedhydroperiodvariationandunderhighandlowdissolvedoxygeninthesoilwater.Inthefieldstudies,sitesrepresentativeofcommonvegetationtypesandvarioushistoriesoflandusewereselected.Thesiteswere(1)longleafpineflatwoods,(2)mixedhardwood--cypressforest,(3)recentlyburnedcypressforest,(4)dwarf-cypressforest,(5)wetprairie,(6)maturecypressforest,(7)mangrove,and(8)recentlydrainedcypressforest.Onegramofseed(approx.34,000individuals)wassownmonthlyoneachoffiverandomlychosen0.2m 2subplotswithina20X20mplotateachsite.Periodicplantingsofseedlingswerealsocarriedoutoneachsite.Seedgermination,seedlingsurvival,growthandsurvivalofplantedseedlings,waterlevelchanges,soilmoisture,ix

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dissolvedoxygencontentofthe 'i.-rater onfloodedsitesIandspecies CQwposition oftheextantvegetationwererecordedateachsite.NosuccessfulNelaleuca establishment occurredonanyoftheundisturbedsites,butafewgerminatedseedlingshavesurvivedonthedisturbedsites.Survivalandgrowthofplantedseedlingsweregreatestonsitesthatwereeitherrecentlydisturbedoronthosewithoutdenseforestcanopies.The greenhouse experimentsdemonstratedthatseedsgerminateinthreedays,even under"ater, butthattheyaresensitivetodryinganddieifnotkeptmoist.Greaterheightgrowthwasobtainedundersaturatedsoilconditionsthanundermoist,,,,ell-drainedsoilcon-ditions,butthere ,,,as nosignificantdifferencein t..'1e averagedryweightoftheseedlingsfromthetwo treatrents. Theheight grO\"th ofseedlingssubjectedto ofsubmergencewasretarded,andlittleornogrowthoccurred "'hile theplants were underwater.Therewasnosignificantdifferenceintheheightgrowthofseedlingsgrownunderanaerobicsoil conditions andthose grCYYln infloodedbutaeratedsoil.Itappearsthatsitedisturbancecoupled ,,,ith periodsoftimeinwhichthesoiliseitherwetorsaturatedbutnotsubjectedtoextensivefloodingarerequirementsforthesuccessfulinvasionofMelaleuca.Thedisplacementofnativevegetationby Melcleucaseems unlikelyinthoseareaswheretheseconditionsdonotfrequentlyoccur. -A'---'/ _,.,_ /1I .__ Chairmanx

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INTRODucrrONThisstudyisanattempttodefinetheimportant environmental andbiologicalfactorsthatdetermine "hich sitesinSouthFloridaaresusceptibletothedevelopmentofnewecosystemsdominatedbytheintroducedtree,Melaleucaquinquenervia(Cav.)Blake.TheSouthFloridaenvironmenthasbeenparticularlysusceptibletotheintroductionandsuccessfulestablishmentofexoticplantand arumal species.Thesesuccessfulinvasionshavebeenbroughtaboutbyhu!nan-causedalterationsoftheenvironmentaugmentingtheeffectsofrecurringnaturalecosystemstresses,andbythefactthatFlorida,withits geographicposition,islikeasubtropicalislandsup porting speciesthatarecharacteristicallycolonizersfromboth the tropicalandtemperatebiomes,plusa number ofendemicspeciesthatareonlyfound in SouthFlorida.Besidestheever-abundantnaturalizedroadside "eeds andtheaquaticweedspecies,muchofSouthFloridaclassedas "etlands hasbeeninvadedbyseveralaggressiveexotictreespecies.TheseincludeMelaleucaquinquenervia(Cajeput),Shinusterebinthifolius(Brazilian-Holly),Casuarinaequisetifolia Colubrinaasiatica,Ardisiasolanacea,and PsiditL.'7t guajava(guava).Thesespecies t,>/ere originallyintroducedforeitha ..!:" ornamentalor com...rnercia.l purposesa.ndhave subse-becoQe naturalizeciin SOD? areastheyhave become themost conspiCllOU3 speciesinthe landscape.Gener2.11yspea..'k::ing, thesespecies ezhibit characteristicsofearlysuccessionalinvadersof aba"1donedfarm 1

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2 fields, roadsideditches, coastalareas,andotherdisturbedareas.Thesecharacteristicsincluderapid shortlifespan,andtheproductionoflargequantitiesofsmall,easilydisseminatedseeds.MostofSouthFloridahasbeenalteredbymassivedrainageprojects,watercontrolprograms,andtheintroductionofnutrientrichwatersfromagriculturalrunoffandsewageeffluent.Theloweredwatertablesandhydroperiodchangesresultingfromthesealterationshaveincreasedtheseverityandfrequencyoffires,alteredvegetationtypes,changednutrientavailabilityandsoilcharacteristicsbytheoxidationofmuckandpeatsoils,andreducedthedurationofannualflooding.Thesealterations have openedthedoortosignificantlongtermchangesintheplantandanimal communities ofSouthFlorida:changesthatwillincludeexotictreespecies well adaptedtothesenewconditions.Ofparticularconcernisthetree,Helaleucaquinquenervia.Itseemstobewell adapted toboththeperiodicfluctuationsinwaterlevelandfrequentburning..Federal aTld statelandmanagementagen-ciesandlocalconservation grou?s feelthatthenativefloraandfaunaarethreatenedbysuchanaggressiveinvader,and that drasticchangesin Floridalandscapewilloccurifitsspreadis alloNed to continue. Cursory--observationsofthedense st2J.'1.Gsand therapidspreadof Helaleueain some areashaveledto itsbeinglalJeled asa "raenace" or"threat" wit..'hout effectively assessi:!.g itspresent a.Tld futureroleintheSouthFlorida ecosysten.Fa::::"eX?;.--:1.:;Jle, theobservations made in thefollovingstatement arein ofthoroughstudy:IlShouldthe Helaleuca to spread itcoulddoin damage.Forone t;-.ir.; it could des-troythe EJerglades asa \.'ildlife Itisdifficultto

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seehowanyformofaquaticlifecouldliveinfloodedareascoveredbyMelaleuca.Forthecoloniesalreadyestablishedpermitnosunlighttofilterthrough.Oncethetreescoveredtheglades,theareawouldbecomeabiologicaldesertfromthestandpointofanimallife."(Smiley,1973).Atpresentitmaybemorerealistictoconsider Helaleuca asanindicationthattheFloridaenvironmenthasalreadybeensignificantlychangedby human activities.Melaleuca might betterbe=nsideredasasymptom,notthecause,ofvegetationchangesandwildlife habitatdestruction.Elton(1958)pointedoutthat"invasionsandout-breaksmostoftenhappeninhabitatsandcommunitiesverymuchsimplifiedbyman",whileOdum(1971)notedthat"aninvadermaybefillingavoidinanewsituationcreatedbymanalthoughmenaretemptedtoblametheinvaderforcausingthedisruptions"..Helaleuca may havetobeacceptedasa neTN speciesinSouthFloridaplayinganactiveroleinthefunctioningoftheecosystem. Perhaps insteadofdesigningspecies-orientedcontrolprograms "'e shouldnotonlybeattemptingtoidentifythisrolebutalsotobeconcentratingcontroleffortstowardenvironmentalmanipulationthatwouldtendtocorrectorreducetheeffecttheman-inducedecosystemsimplificationthathasfavoredexoticweedspecies.Somebasicquestionsthatneedtobeaskedandinvestigatedare:(1) 11hat environmentalconditionsareconduciveto He1aleuca establisrunent? (2) ecosystemsor aresusceptibletoinvasion?(3) tfnat effect \..,ill thesec.. have on both thenaturalandhumansystemsandtheirinteraction? what benefitsordetrLIr,ents 'dillvegetationchangeshave onnatural ar:.d urban \-iater supplies, .. ,;ildlie,recreation, ruLd overall image ofSouthFloridaas an attractiontotourists
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4Includedinthisreportare a oftheG1.aracteristicsofMelaleuca,itshistoryin South Florida, thedescriptionofseveralgreenhouseandfieldinvestigationsthat attempt to,ifnotanswer,atleastshedsomelightonthesequesti.onsandprovideabasisformorethoroughstudiesinthefuture.Characteristicsof Nelaleucaquinquenervia(Cav.)Blakeisa maTt".ber ofthe Nyrtaceae familywhichiscomprisedofabout80genera,i.ncludingEucalyptus,Callistemon,andPs;clium,eachof whic.'-lhas beenintroducedintoSouthFlorida,andinthecaseof successfully naturalized. Althoughtherearenumerousspeciesof the genus as ornamentalsinFlorida,only Nelaleuca quinquenervia h2.Sbecorr:e naturalized(Sachet,1953).Until authorshave cessribed the species as !
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5 (Ewart, 1917).It lias originallydescribedfrom specisens collectedinIndia \olhere itisnotbelievedtobenative (EHart, 1917).Melaleuca quinqusnervia isaslenderuprighttree,12to30minheightandveryoftenfoundwithmultiplestemsapparentlyresultingfromfrostorfiredamage whenyoung.Thestemsareoftencontortedandcoveredwithlayersofthick,spongy Hhite bark.Theleavesarealternate.Theflowersarewhite,sessileandborneon many floweredspikesfrom3to12emlongconsistingof30to70flowers(Fig.1).Eachflowercontainsasinglestigmasubtendedby30to40stamensandfive Hhite petals.Thespikesareborneontheterminalendsofthebranches,with ne,,, branch grm-lth andleavesappearingafterflowering(Meskimen,1962;LongandLakela,1971). FloHering inSouthFloridahasbeenobservedtooccurthroughouttheyear, \"ith generallyheavybloomsduringthewetseason,Junethrough November, but \-lith onlysporadic occurringduringthedryseason which occursfrom. Decell'ber through Nay..Neskimen (1962)notedthatindividualtreesmaybloomas many asfivetirr.esinasingleyearandindividualbrancheswillsupportthreeor more bloomsannually.YOt.U1gtreeswereobservedtobloomintheirfirstyear.AlthoughMelaleucaseedsareminute (Meskimen,1962),theyareunwinged itisverycommontofind dense Melaleucareproductionaroundthebaseofaseedtreewithonlyscatteredindividualsanydistanceaway. HO'o..;ever, therapid growth ofthesetreesandtheir ability toproduceseedwithina yearor suggeststhatitcanspreadrapidlyfromanyisolatedindividual.A b'lig orbranch maysupport several :=ied cropsofdifferentages, \.;:-tich canbeeasily d-21ineated. Flot .... ers ah-:ays producedon the

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Figure1. inflorescenceandsertinousfruits.6

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7presentseason'sgrowingtips,andbranchelongationcontinues beyond theinflorescence.Thus,theseedcapsulesfromeachbloomformuniqueclustersthatareseparatedfrompreviousandfuturecapsulesbythestemelongationoccurringbetweenbloomingperiods.Theseedshavebeenshowntoremainviableforatleastseveralyearswithintheseedcapsule(Meskimen,1962).Indicationsarethatavascularbreakbetweentheseedcapsuleandbranchwithsubsequentdryingofthecapsuleisnecessaryforseedrelease (Meskimen, 1962).Thus,sporadicseedreleasemayoccuratanytimeoftheyearbyoccasionalcapsulesbeingseparatedfromtheirvascularconnectionbyradialstemgrowth,stembreakage,frostdamage,andnaturalpruning;massiveseedreleaseoccursafterburning. Neskimen (1962)showedthatseedcapsulesonbrancheswhoseleavesweremerelybrowned,theseedcapsulestooksomewhatlongertoopen.Meskimen(1962)alsonotedthatseveralmillionseedscanbeshedbyasingletree.InJava,whereMelaleucaisnative,forestsareregeneratedafterloggingbycuttingoffthebranchesandburningthem.AccordingtoBurkill(1935), many Javanesebelievethatfire ma'ltesl1elaleucagrOT" moreluxuriantly.TheabilityofMelaleucatoaggressivelyinvadevarioustypesofsitesisinpartaresuitofitstolerancetobrackishwater,flooding,completesubmergence,andfire. possessesseveralanatomi-'calandmorphologicaladaptationsthatfacilitateitsabilitytothriveundertheseconditionsandtorapidly suitablesites.Theseadaptationsorcharacteristics include the thiCk, fire-insulatingbark,afire-triggeredseed releasemecha.."lsm, thestorageforextendedperiodsofmillionsof seeds on a single tree, theproductionofadventitiousroots,andthe ability tosprout and stensafter felling.

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Melaleucaquinquenerviahas beendescribed inAustralia(Bailey,1913),NewCaledonia,Borneo,Java,Burma,Malaysia,andVietNam(Swain,1928).InAustralia,whereitisknownasweepingorriverteatree,itisfoundinbrackishcoastal s'.
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9(1952)and Chow (1969)have sho-.;" thatthese"gelam"soils are extremelyacid:aresultofthehighconcentrationsofsulfidesinthesoil.Duringthedryseason,orafterdrainage,thesulfidesare oxidized, formingsulfates,sulfuricacid,and toxic levelsofironandaluminum.AlthoughMelaleucaappearstotolerateveryhighconcentrationsofsulfurinthesoil,Coulter(1952)foundthatitdoesnotabsorbparticularlylargeamountsofitandthatitisnotlimitedtosoilswithhighsulfurcontents.InVietNam,whereitisknownasIItram", Nelaleuca islocateddirectlybehindthemangrovesandiscalled "bad<-mangrove"(l'lillia.'lIS, 1967).Here,again,itgrowstoabout10minheightonsandysoilsinundatedwithfreshtoslightlybrackishwaterduringthewetseason ,.,hile beingdrainedandsubjecttofrequentburningduringthedryseason.Somebotanistsconsider Nelaleuca tobeasuccessionalspeciesfollowingmangroveandtheyfeelthatitoccupiessitessimilartothoseoccupiedbyPterocarpusofficinalisinPuertoRico n'lilliams,1967). Outsideofitsnativerange, has becorn.e naturalizedinthePhilippines 1953),India(Dastur,1951),Madagascar(Louvel,1951),Zaire(Neybergh,1953),andHawaii(Neal,1948).InthecontinentalUnitedStatesithas establishedinSouthernFlorida,California,andTexas (Horta.." 1966).Usesof Melaleuca Nelaleuca was originally i:r.-:'roduced intoSouthFloridaasapossible SQu!:"ce of ra','/ materialfor a ne'.;rO:::2stAlthough ithasnever itis 2evoid orpossibilities. its entire nat.iverangetheuse of hasbeen asa source

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10of fuel. Incertainareasof Vie::Na..rna'1dNalaysia\olhare mangroveisnotavailable,Melaleucaforestshavebeensetasideassourcesoffuelforlocalvillagers(Burkill,1935).Melaleucawoodhasbeendescribedashard,durable,andclosegrained,butchecksreadilyuponseasoningandtendstobebrittle(Schory,1958).Thewoodisresistanttotermiteattack,isdurableinwaterandhasbeenusedforwharfpiles,boatknees,andrailroadties.It lias beenrecommendedforfurniture,cabinets,flooring,gunstocks,framing,boattrim,andnoveltyitems(Schory,1958).Itisnotparticularlywellsuitedforpulp.Pulpingtestshaveshownthatthepaperisstrong,buthighbleachingtreatmentsarerequired(Curran,1934).NumerouslocaluseshavebeenfoundforMelaleucabarkandleaves.InIndia,thebark 'vas originally 'Used asaformofpaperforsacredwritings(Dastur,1951).Thebarkis checically similartocork (v/ilks, 1953) hasbeenusedas material,floatsforfishingnets,insulation,and bedding. Itismildewproof hasbeensuggestedoruseinmattresses,upholstery, pillovTs, andlifepreservers(SchoryI1958).Itisalsousedlocallyforleak-proofingroofsandforcaulkingboats(Corner,1951).In New Caledoniaateaismadefromtheleaves(Burkill,1935).Thearomaticvolatileoil,cineol,is distilledfromtheleavesandisusedtotreatavarietyofillnessesand symptoms. Theseinclude headache,earache, andcramps.It isDostcor..illl.onlyused in ointr:'.2p.t.S for ski.ndiseases andasan expec-Tne islandsofBoeroe 2':;"::Ceramin:':alaysia havebeenthe c!lief exportersof the oil.Ec.. it is Doreexpensive than

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11 oilandthequality arequiterigidinthe United States,soits cowmercial hereislimited 1966)Theoilhasalsobeenpromotedas excellentmosquitorepellentforcertainspeciesofmosquitoes.andithasbeenusedtoridanimalsofliceandfleas(Guenther,1950).InFlorida,treeshavebeenplantednearhomesandaroundpastureswiththehopeofreducing t.t,e mosquitoproblem.Somesuccesshasbeenreported (Schory, 1958).Recent.lyithasbeennotedthat Helaleuca hasbecomearespiratoryirritanttosensitivepeopleandcausesallergicreactionsinsomepeoplewho comeintophysicalcontactwithit(Mortan,1969). Wnen Melaleucahoney sta-rted showing up inbeehives,Floridabeekeepers "'!ere concernedthatit destroytheirindustry.Thehoneywasreportedtohaveadistinctivetaste and tobefoulsmelling.Sincethen,ithasbeenfound that byblendingthehoneyitis salable tobakeriesandhealthfoodstores t' and 1!elaleuca hasbecome importe...:...,.t forproducingpackagebeesand 1 .. iax (NortaP.., 1966)..IntroductionandSpread of MelaleucainSouthFloridaMeskimen(1962)compileda cOrJprehensive narrativedescribingthe peopleand areasinvolvedintheintroduction a..,d culturalspreadof Helaleuca inFlorida.To revie,,;t..-heseq'.:ence briefly,Nelaleuca 't,'asint!':oduced into BrONard Courlty Davieby Dr. John C. Giffordin 1986 seedhe Sidney Gardensin Australia. He specifically a species,,;ith the characteri:;tics0: theEucalyptus th2.t::;--.stal:1 bot:::'tr.e floodingandfiresof thsFloric..a

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12Atapproximatelythesame A. H. oftheKoreshanUnityNurseriesatEsteroinLeeCountyobtainedseed from Melbourne,Australia.Meskimen(1962)pointedoutthat, from twoindependentdescriptionsoftheSouthFloridaclimateandtopography, t,.O Australianauthoritiesindependently recomwended Melaleuca.Severalotherintroductionsmayhaveoccurred,possiblyfromseedobtainedoutsideofAustralia,buttheauthenticityoftheseintroductionshasbeendisputed.\'ihenHelaleucafirstescapedisnotknownbut presuma!:>ly itoccurredwithinafewyearsafteritsintroduction.ThereareindicationsthatA!ldrewsmayhavescatteredseedonvarioussitesandaventodaytheKoreshanUnityconsiderHelaleuca irrportal!t inrefores'tation.In1936,H.SterlingofDaviescatteredseedfromanairplane over largeareasof \'1esternBrorllard County.Itsuseas a..'1 ornamental,as Nindbreaks, andforfence rows hasledto the establishmentof ma.71Y isolatedpocketsofreproduction.In1940 alla 1941theU.S.ArmyCorpsofEngineersoperatedaMelaleucanurseryandplantedthespeciesalongtheleveesoftheLake Projecttoprotectthemfromerosion.AreasBeingInvadedinLee CollierCountiesSeveralecologistshavedescribed naturalfeaturesofSouthFloridaandhavenoted i..;ith concerntheintroductionandspreadofexotictreespeciesincluding Nelaleuca.7hep.":ostcomprehensivede:scriptions hav2 beenwrittenbyDavis (1943) f (1971)1and Alexander (1973).'l'he follo',.iing isa oftheirdescriptions.SouthFloridais by flat. and 5 upporting diversepI commur-itiesdeIir'.'2by slightchangesin

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13elevationandthe concor::...mtant effectsof drai!1age, salinity,andfirethatthedifferentwaterregimesprovide. rainfallis about 1700rom,withthemajorityfalling bet,,,eenNay andOctober.VastflatlandsoneithersideofLakeOkeechobeesupportopenpineflatwoodsofPinuselliotii(slashpine)andextensiveareasofpalmetto,grasses,sedges,andforbes,calledwetprairiesordryprairies,dependingontheextentofsurfacefloodingduringthewetseason. l,ithin theflatwoodsandprairiesarescatteredcypressdomes,sloughs, hardwood hammocks,andmarshes.TheWesternFlatlands,asdescribedbyDavis(1943),extendasfarsouthasnorthernandwesternCollierCountywheretheygraduallygivewaytocypressswampsandwetprairiesintheEvergladesBasin,theBigcypress Swamp, andt!lemangroves.Alexander(1973)describedindetailthevegetationcllangesthathavetakenplaceinSouthFloridaoverthepast30yearsduelargelytotheactivitiesofpeople.TheWestern Flatlands, wheretheyextendintoLeeandCollierCounties,werelumberedextensivelystartingin1925.AtpresentlargeareasnearNaplesandFort Nyers havebeenurbanizedorareslatedfordevelopment.Becausethe vIes ternFlatlandsaregenerallyhigherthanotherareasandhavewell-drainedsandysoils,theneedforlargedrainageprojectshasbeenlimited.TheextensiveGoldenGateCanalSystemdoesextendintothesouthernmostpartoftheFlatlands.Increasing oflandarebeingconvertedtofarming,citrus,andcattle rcnching, but these havegenerallysparedthecypressstandsandsloughs.Fires have playedanactiverolein maintainingvegetation types illiC locallycause damageduringdroughtyears..Asfor Jl..lexander (1973)statedthatliThe great.est threatto vrhat isleftofthe origir:.3.l ecosystemisthe rarnpant

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14invasionofcajeput.Thefateofthenaturalsuccessionintheinvadedareasofcypressandpineis Veryfew ifanynativewoodyspeciesareseenunderthedensecajeput ca."1Cpy." TheBigCypressareasouthofthe Western Flatlandshasbeensubjectedtovariousdegreesofmanipulation subsequentvegetationchanges.Loggingofthecypressandpineoccurredbetween1940and1957.Theremovalofmostofthematurecypressfromthelargestandshaschangedtheirspeciesmakeup. Farming intheBigCypresshasbeenlimitedandgenerallyunsuccessfulexceptforcattleranchinginthenorth.Drainagecanalshave probably beenresponsibleforthegreatestchangesinthewesternportionofthe Drainagehasloweredwaterlevels,extendedthedryperiod, subjected theregiontomorefrequentfires.These changes appeartohaveenhancedthe mentofpineintoareasformerly occupied bycypress.TheBigCypresswatershedhasbeen divided intothreesubregionsdelineatedbythedirectionofwaterflow fu"1d theextentofman-causeddrainage.SubareaAcoversabout1165 squarekiloilleters(450 squaremiles)inthenortheasternpartofCollier ItdrainsinasoutheasterlydirectionintoConservation 3and intoEvergladesNationalPark.SubareaBincludes1425squarekilometers(SSGsquaremiles)atthewesternendof BigCypressandisdrainedtothesouthandwestbyanextensive ofcanalswithin the GoldenGateand Union 7hese canals,which were completedin1970, haveac:celerat-:;druooff:3:.::: possibly lot... ered Hater levels as muchas1.2 meters in a140 (54squaremiles) areaeast of Ncples. SubareaC covers3755 (1450 squarer1iles) ofeastern CollierCoun::y;::::-ept for theTa.i11iami,

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15TurnerRiver,andBaronRiver Ca.."1alsl drains naturally tothesouthintothewesternhalfof Everglades NationalPark(Klein,1970).Muchofthecypress s\'/arnp insubareaC re.r:tainsinu...'1Ca.ted orwetforallbutthreeorfourmonthsoftheyear.Eventhoughfirecausessomedamageduringdroughtperiods,littlevagetation cha'1ge hasbeennotedoverthepast30years(Alexander,1973). l;uc:h ofsubareaBwasformerlyinundatedeachyearduringthewetseasonbut withthecompletionoftheFahkaUnionCanalandtheGoldenGateSystem,thisareaiseffectivelydrythroughouttheyear.The pricar.i functionofthesecanalsisto latHerpeal.<. waterlevelstoprevent ilooding. The Fah.'<:a UnionSystemcontainsabout30";eirstocontrolflowandreducethepossibilityofoverdrainage.Becausethe ca..Tlals are shalloT,'1 ithasbeenstatedthatdrainagefromtheshallowaquiferthatsupplieswatertoNaplesislimited (1cCoy, 1972).ThesoilsinCollierandLeeCountiesconsistof sa""lc.s andmarlsofvariousdepthsoverlyinglimestone roc<. In manyplaces therockisexposedorjustbelowthesoillayer.In t."-e:'lestern ?latlandsthesoildepthtolimestonerangesfron3to100m,whilein the BigCypressandcoastal areas thelimestone may beexposed a...'1.d pittedwithsolutionholes.Generallythesoildepthisfrom0.6to1.5m.Thesesoilsarepredominantlyfine5ands,butin depressionsand. slaughstheamountoforganicmattermay thetexture (Leighty,1954).Themost CODr."!on soiltypesinthepine la.:H1s of LeeandCollierCounties are Arzell 2ndPcspano fine s2 ... rlds.T21.'2"S3 are CL."r.aracterizedbybeing level,slightlyacid, andpoorlycrained. Much ofthe BigCypress regionthatis:l.otrockla.ndorS2...'1ic isoccupied

PAGE 26

16byvariousphasesofOchopee fine sandy Earls. Theseconsistof turesofmarinesands recent depositsof marla Thedepthmayrangefrom15to90em(Leighty,1954).Organicsoilsarefoundinthecypress swa.'llpS, sloughs,andponds.Inareasthathavebeendrainedandaeratedorburned,thedepthofthesesoilsisgreatlyreduced.Theorganicsoils va..ry from5to8emlayerof mud
PAGE 27

17 Psidiwn, andLantanain theabsence offire(Sachet,1953)..WhethertheeliminationoffireinSouthFlorida would haltthespreadof leucaandallowsuccessiontoreclaimMelaleuca-dominatedsitesisnotknown,butanyattempttoeliminatefireinordertocontrolMQlaleucawouldleadtodrasticchangeswithinthenativecommunities,whichalsoburnundernaturalccnditions.TheFortMyersDistrictoftheFloridaForestService,whichincludesLeeandCollierCounties,annuallyhasthelargestacreageburnedbywildfiresintheStateofFlorida.ItalsosupportssomeofthelargeststandsofIlelaleuca. Huch ofthisareaissubjecttoburningatanytimeoftheyear.For exazrple, intheFort 11yers districtin1972,21%ofallfiresoccurredinMarch,21%occurredfromJunethroughAugust,and40%ofallfiresoccurredfrom Ilay through Septerrber (Hofstetter,1973).Dataontheacreageburnedduringtheseperiodsisnotavailable,butgenerallythefiresinthewetseasonarelightningcaused, alrrostah
PAGE 28

18 capaci.ty?\ViIIHelaleucaperpetc.ateitself a'1dfacilitateitsownspreadbyalteringthehydroperiod,dryingsurfacesoils,andproducingconditionsconducivetofire? ars theeffectsofhavingacontinuallyclosedcanopyoveranecosystemthatnormally(inthecaseofcypress)shedsitsleaves,resultinginhighlightintensitiesatgroundlevelduringthewinter?Toprovideabasisforotherstolateranswertheseproposedquestions,thisstudyattemptstoidentifytheconditionsrequiredby forsuccessfulestablishment a.'1d toascertainifthereexistsarelationshipbetweenthespreadof 1(elaleuca andhuman-causedenvironmentalchanges.Bydefiningthetypesofsites a.'1d conditionsthatarefavorablefortheinvasionof Melaleuca, a Fore realisticevalua-tionoftherolethatMelaleucawilleventuallyplayinSouthFloridacan be made.Forthepastyearseverallaborato:ry and greenhouseexperimentshavebeenintegratedwithongoingfieldstudies,fieldobservations,previousstudies,andmodelstoprovide intotheinvadingcapabilityofMelaleucaundervarioussiteconditions.Descriptionsof experiITnts andfieldinvestigationspresentedinclude(1)modeling;(2) germination tests differentmoistureconditions;(3)initialseedlinggrowthandresponsetovarioushydroperiodsi(4) HelaJ.euca establishmentona ofsitesduring seasonsoftheyear undervaryingmoisture and(5)seedlingsurvival of naturallyestablished Fieldstu6es 2.1S0includedthe ofinvasion patt2rns,observa=ion of site conditionsat tr.e border betHeenstar:dsand vegetation.

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MODELINGHodelingandcomputersimulationare important toolsforlookingatanentireecosystemandtryingtotietogethervarious components ofaproblem. /1odels canbeusedbothforillustratingexpectedresponsesundervariedconditionsandforprovidingcluestoimportantparametersandvariousavenuesof approac.'J. thatmaybeutilizedininvestigatingaparticularproblem.Preliminarymodelingisusuallydone t;:hen aninvestigationisinitsinitialstagesofformulationanddevelopment.Modelingatthistimeforcestheinvestigatortoidentifythoseaspectsoftheproblemthatareprobablysignificant.Ifthemodelisthen supportedby fieldobservationand measurerrent, thedatacollectedcanbeusedtodevelopmorecomplexmodels1toextendthescopeofa model simulationbeyondthetimerestrictionsencounteredinthefieldstudy,andtomanipulatedifferentparametersforpredictivepurposes.Inthecaseofthisstudya preliminary modelwasdevelopedduringtheinitialphaseofthefieldand laboratorJ investigations.ProcedureFigure2isa siw:?leprelimir'lary energy modelofcypress asthey areaffectedby'daterandfire..'The rr.Od2l illustratesthe biospecies utilizingan li.'1.1ir.titedresource. Periodic drou.ght-inducedfireburr.s both cypressandbio[:1.ass I \';:"1ile 19

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'. Figure 2. Prelicinary model showing Melaleuca andcypressutilizinganunlimited resourcebut b,dng differentially affected byfire.

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burnedk 6 M+k 7 M-kSC Z k 1Rl-! +0kZH kJRC+I-'k4CZC M. k 6 MHe1a1euca Burnedc-HI k 1 It'!rcnource:Lc L-Lm '"....

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22atthesametimetriggering Nelaleuca seedrelease.Themodel was scaledusinggeneralizedbiomassandenergyflowfigures(Table1).Firewasinducedbysettingathresholdlevelforthewatertable.Inotherwords,belowacertainamountofwaterstorage,conditionswouldbesuchthatdestructivefirewouldoccur.Theseverityofthefirewascontrolledbytheamoul1tofbiomassconsumed.I'laterlevelfluctuationsweresimulatedbyusingasinewave:theundulationrepresentingtheriseandfallofwaterlevels.Inthiscaseeachcyclewastime-scaledtorepresentasix-yeardroughtcycle.Becausebiomasslossorincreasedoesnotsignifyanactualincreaseinareaoccupiedorbeinginvaded,alandoccupancyfactorisincluded.Landoccupiedbyonespeciesisdependentonitsownbiomassincreaseorloss,ontheincreasesandlossesofthecompetingspecies,andonthelandoccupiedbythecompetingspecies.ResultsThethreesimulations'presented(Figs.3-5)showtheincreasingeffectsofloweringthe levelandsubjectingthetwospeciestovariousdegreesoffireseverity.Inthefirstsimulation(Fig.3)thedroughtwasnotsevereenoughtotriggerafireandnoexcesslossesoccurredoneitherspecies.Bothcontinuedtoproducebiomasswithintheconfinesofthesitesthattheyalready occupied. Growthcontinued until asteadystate\-laSreached.Astheseverityof droughtincreased(Fig.4)destructivefiresoccurred.Duringeach droug'Clt periodbothspecieslost bio::13.ss.!:elaleucasustained lessloss due toitsfirereleasedseedand fire.resistance. Cypress,although burned eachdrought

PAGE 33

23

PAGE 34

9Cl6ICypress .......... LandinCypress :? 40 ....N:-<>
PAGE 35

690'+ILandinCypress Melaleuca I f./I/I /I 1\1\ Abtf.-INX I\//\/\/\/\/\/\/\JCypress N (;Lr.,'-' u u :': u C UlQUl2:';:,8H'" ILandin _Nelaleuca 106121824Years30364248Figure4.Simulation #2 showingboth andcypressbeingburned byperiodicfires,'butwithnoMelaleucainvasiontakingplace. '"lJl

PAGE 36

26period,quicklyreturnedtoits thuspreventinganychangeinthearnountofland occupied by either ofthe tHo species.Inotherwords,cypressbiomassinthe fOn:1 ofleaves,branches, a."1d seedlingswasreadilyconsumedduringburning,butthefireresistanceofthelargertreesandseedinputpreventedanychangeintheoccupancyoftheland.Asdroughtsbecamemoresevereduetoartificialdrainage(Fig.5),firecausedmoredamagetocypressthanto t'1e1 aleuca.Thetreesweredestroyedtosuchanextentthatthecypressforestdidnotrecoverbeforethenextdroughtperiodand tite sitewasopento Helaleuca invasion.Thethreesimulationsillustratetheincreasingeffectofhydroperiodshorteninguponthecypress ecosyster.l, andtheimportanceoffireasaprinciplefactor thecapacityofcypresstomaintainitselfonasite ,,,here thehydroperiodisalteredanddroughtseverityincreased.Ontheotherhand, fiz:-enayhave astimulatingeffectonMelaleucagrowthandsiteinvasion.

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tJ0,:::> u uo Cl:i 90 _,_ 6 "'.x NI "" u -,.' (fl til"" 2 ;:.:cH'0 MelaleucaLandin tlelaleucu. Cypress10612182430YEARS364248 Figure 5.Simulation113showing llii!-aleu...'!. invasionofcypressforestsafterperiodicseverefires. '"...,

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SEED GERI1INATION IIITHE LABORATORY Meskimen(1962)suggested t.hatt.!].e different-agedseedcropsonatreemayexhibitdifferentdegreesofviability.Heselectedeightseedcropsfromonebranchandgerminatedthemundercontrolledconditions.Hisresultsshowedthatthemostrecentseedcropexhibitedtheleastgerminationwhilethethirdandfourthcropsproducedthebestresults.Thesecondcropwas wirrway betweenthesewhiletheoldercropsgerminatedmoreslowlyandproducedslightly less the average germinationrateof20to28%.Theresultssuggestthattheseedsrequirearipeningperiodwithin capsuleandthatolderseedsrequireslightlylongerexposure t.of2.vorable conditionsin order toeffectgermination. JakirrDva (1965)shoT. .;ed thatstratificationretardedthegerminationofMelaleucaseed.ObjectivesMelaleucaseedrequiresonlyafewdaystogerminate.The rrois turerequirementstoinitiate gemination arethusprobablyeasilysatisfied.However,forsuccessful moistconditionsmustbemaintainedoveralong of tir.e. Thissuggeststhatsuccessfulgermination be liQited tocertainseasonSoftheyear whenadequatenoisture isavailable, andthat seed ca."'1 be easilydestro:,.'eaifinitic.l levels are notmaintained. Thedescribedin section wasattempted to gain28

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29informationon(1) thea.l'.ount ofgenninationtobeexpectedunderidealconditions;(2)the ofdaysneededtoeffectgemination;and(3)theeffectofaninitial period ofITDisturefollowedbydryingongermination.ProcedureFivebatchesofthree hlL'leu:-ed NelaleucaseedswereselectedrandomlyfromseedcollectednearEsteroinLeeCounty.Eachbatchwasplacedinapetridishonfilterpapermoistened ,,,ith distilledwater,covered,andplacedunderalightbank(2000F.C.,12hourlight/darkcycle)inanairconditionedroom(23to26C).Asixthbatchwaspreparedinasimilar ma...'"1Iler buttheseedswere subIi'.arged underapproximately1 emofdistilledwater.Theseeds would ifsurfacetensionwasbrokenbyagitatingthewater.Aseventhbatchwaspreparedwith300seedsselected seedcapsuleslocatedonan8-em diarr.eter mainstem,thusinsuringthat the seedswereatleastseveralyears old. Thefirstfourbatchesofseedweresubjectedtodifferentschedulesofwetting,drying,andrewettingbyremovingtheglasscovers.Treatments5,6,and7remainedcoveredforthedurationoftheexperiment..Dailyseed ge.rrnination1',.;astabulated fortendays..Thetreatmentschedules resultsare in Table 2. Re.sults Germination was thethird day inthecentral and the sUa!:':'.e.rgedtre3.t::r:t'2nt.s. one day intreatments #1'and?2aDd 2 c1a'{s in treatrc.ent:0:3. Thirteenseedsgerni._rlatec1 in trea-tP.1entcefo2':"c dry pC2':"iod, allof Hhich died before

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2.Daily,total,andpercentgerminationobtainedfromsevenbatchesof300seedssubjectedtodifferentmoistureregimes.GERMINATIONTESTSDayNo.Treatment1/21 2 3 4567 8910Total%1Wet12hoursthenairdried0dry00 66 211616 2 0 01214012hoursbeforerewetting0----2 Wet 24hoursthenairdried00dry013352173 00 70 23 24 hours beforerewetting0._------------------------------------3 40 hoursthenairdried000dry01924 3 10 0 471624hoursbeforerewetting0 4\'et 72hoursthenairdried00013dry0015138 0 36 12 24 hoursbeforerewetting0 i-5Control---moistconditions00 0126211411150 0115386Submerged0001440 2 3 15400 78 26 7 Seedsfrom oldcapsules--00 002328 7116007525moistoonditions w o

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rewettin9andfurther gerr.UnationHasdelayed 2moredays. Treatr:1ents#1 and #5 (Control)exhibited the greatestgerminationpercentage.Lessgerminationoccurredasthedryperiod carre later.Theolderseedsintreatment #7 andthesubmergedseedin treatl1'ent #6exhibitedapproximately35%lessgerminationthan t.1>e control.31

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HYOIDPERIOO VARIATIONINTHE GREENHOUSE exhibitsapreferenceforsitesthatareperiodicallyfloodedand,at least undersomeconditions,its seeds willgerminateunderwater;theseedlingswilltoleratetotalsubmergenceforanundeterminedamountoftime.Treesgrowinginfloodedareasdevelopafibrousmatofroots just belowthehigh-waterlevel,andthisrootmatisapparentlysloughedoffattheendofeachwetseason.Large,permanent,woodyadventitiousrootshave been observedontrees intheimpoundedwatersofConservationArea3inDadeCounty,wherethesoilsurfacemayremainsaturatedevenduringthe dry season..Adventitiousrootsmaydevelopon any partofthetreethatisincontactwiththewater,includingbranches,horizontal andleaves.GreenhouseexperimentsconductedbyMeskimen(1962)indicatedthatMelaleucawillgrowbetterinundrainedconditions,andthatplantssubmergedfor84daysdidnotlosetheircapacityfornormalgrowthoncetheexcesswaterwasremoved.ObjectivesThisgreenhouse experirrent wasdesignedto(1) deterr.dne theeffectofdifferentwaterregimesonseedling anddevelopment,and(2) gain informationonthelengthof ti:we seedlingscan standsubmergence.32

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33ProcedureBatchesofapproximately300seedswereplacedinatotalof3513-ernclaypots=ntainingagreenhousesoil-sandmixture.Thepotsweredividedintosevengroups,eachgroupconsistingoffivepots.Eachgroupwassubjectedtodifferent treatP.'.ents ofwaterlevelflue-tuationbyplacingthegroupsunderdifferentschedulesofsubrr.ergenceusinglargegalvanizedsteeltubsfilledwithGainesvilletapwater(Fig.6).Waterlevelwasmaintainedatleast10ernabovethesoilinthepotsandthewaterwasreplacedonceaweek.Thedifferenttreatments(Fig.7)wereasfollows:Treatment#1-Soilmaintainedmoistbutwelldrainedforthedurationofthe experiment. Treatment#2-Soilmaintainedsaturatedforthedurationoftheex- periment byraisingthepotswithinthebasinssothatthewaterlevelcorrespondedtosoillevelinthepots. Treatnent #3-Thepots \overe alternatedonatwo Heekbasis" beingsubmergedfor 0';0,".,reeks inthetubthenremoved al1d maintainedmoistbutwelldrainedfor UNO weeksbeforeresubmergenceforanothertwoweeks.Treatment#4-Potsalternatedeverythreedaysfromsubmergedtodrained. #5-Soilkeptmoistbutdrainedfortwo months andthensubmergedfor the durationofthe experiment.Trea'tment #6 Soilkept rroist butdrainedforone month andthen slL0merged forthedurationofthe #7-Potscontinuously subffierged forthedurationofthe experirr:ent.

PAGE 44

34 6. Two treatmentsinthehydroperiodvariationexperiment.Left:Fivereplicationsofthesubmergedtreatment.Right:Fivereplicationsofthesaturatedtreatment.

PAGE 45

Figure7.Diagramofthetreatmentschedulesinthegreenhousehydroperiodvariationexperiment.

PAGE 46

\:... MOISTWELL-DRAINEDSATURATED _Ib' IIII j.nil"'"r'AI'T'WO'1'''TED I TWO DAYSDRAINED--TWODAYSFLOODED TWO MONTHSDRAINED--FOURMONTHSFLOODED 8, IONEMONTHDRAINED--FIVEMONTHSFLOODED rei, 1FLOODEDFORSIXMONTHS 8 I -, o1II2 3 HONTHS r I456W 0\

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37Oncegerminationoccurredtheseedling3werethinnedtotentreesper pot. Height growthrr.easurements weremadeafter3 roonths and6months.After6months,treatments1,2,3,and4wereharvestedforrootandshootdryweightdeterminations. T-.-lO potseachfromtreatments5,6,and7werereIlIOvedfromthetubsandmaintainedmoistbutwelldrained.Theotherthreepotsofthesetreatmentsarestillbeingmaintainedunderfloodedconditionsafter12 ITDnths. ResultsTheseedsineachofthetreatmentsexhibitednogrossdifferencesingerminationrateortotalgermination.Nocountsweremadebecausetheamountofseed sm... n "as onlyapproximate.Afterthinning,someseedlings "ere lostbythemechanicaldisturbanceencounteredwhileremovingthepotsfromthe \vater andviceversa.Theselosses \'lere notincludedinthecalculationofaverageheight grol-lth andaveragedryweight;therefore,itispossiblethattheseedling gro"th mayhavebeengreaterinthosepotswithlessthan10seedlingsduetolesscrowdingandcompetition,butthisisunlikelytohaveaffectedtheresultssignificantly.Nolossesoccurredthatcouldbeattributedtothedetrimentaleffectsofaparticulartreatment.Thecomparative growth differencesafterthreeandsixmonthsareshowninFigure8.AverageheightineachoftheseventreatmentsisillustratedinFigure9withthe measurements after3 6months.After3monthstheheightwasgreatestinthewell-drained treatnent (#1) aY,,'eraged 13.0empertree, Hhile thetreesinthesaturated treatf:1.ent(#2) anaverage11.9 c:r:'. per tree.He-asurerC':en ts ta.k.cn afte:c6 monthssho,,;edthatthe averageheight

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Figure8.Growthdifferencesinthehydroperiodvariationexperimentafter(a)threemonths;and(b)sixmonths.

PAGE 49

(a)39(b) lJo.terl09g ed ;3",....2.wl!a.1:J.2wJu .subtrlvy_cl.2montllsout

PAGE 50

AVERAGE nEIGHTOF SEEDLINGS(em) ...., N W.t:-o0 0 0 ... a '"wa6zf;!:;lInCI)"1....:JQC'1(l)'"'HOISTHELL-DRAINED"'"r.... ;l'" SATURATED ,...or......-.-........t-t_I-I_I_._X(l),...z]j=< o ;:r'" nc,::to ALTERNATED '"H>nn,oHEEKS DRAINED-:.:r'THOl';EEKS SUBHERGED '"'" ro '"c. ALTERNATED >-'.... THREEDAYSDRAINED-;l THREEDAYSSUBHERGED '"....;:1"THO HONTlISDRAINED '"" THENS UJJHERGED:::rn'1'",.>rt" ONE HONTI! DRAINED "" THENSUBHERGED n'",."n'"'1nSUBHERGED SIX NONTllS:r'1'""

PAGE 51

41oftheseedlings grown inthe sat1..lrated soil(#2)exceededby12emtheaverageheightoftheseedlings grown inmoistwell-drainedsoil(#1).Usingat-test,thedifferencebetweenthemeanswasdeterminedtobesignificanttothe99.5%confidencelevel.Althoughtheseedlings grmvlng inthesaturatedsoilwereconsiderablytallerthanthoseinthemoistwell-drainedtreatment,theyseemedtoproduceweakerstemsthat >lere unabletosupporttheaerialportionsinanuprightposition.Thismaybeanormalresponseinarapidlygrowingtree;however,itappearsfromtheverylittledifferenceexhibitedbetweentheaveragedryweightsoftheshootsandrootsfromthesetwotreatments(Fig.10),thatlessbiomassisproduced saturatedsoilconditions.Possiblymoreintercellularspacesareproducedundersaturatedsoilconditionstofacilitatethediffusionofoxygenthroughthestemtotheroots.Therootsintreatment #2 (saturatedsoil)alsoprotrudedabovethesoillevelaroundtheedgesofthepot. l1hen theseedlingsinthistreatmentwereharvested,itwasfoundthataconsiderableportionoftherootsystem 'vas betweenthesoilsurfaceandadensealgalmatthatdevelopedoverit.Theseedlingsintreatments6and7(submergedmostorallofthe tirre) producedleavesthatappearedtobemorphologicallydistinctfromnormal leaves. Theywereconsiderablysmallerthanthe normal leaf,morelanceolateinshape, and. developedinatightrosette T".,ith outanyapparentlengtheningoftheinternodes. The seedlingsintreatment#5(moist2 thensubmerged)losttheirnormalleavesafter subQergence,thenproducGclusters orrosettesof leaves attheendof the stem. Athie:21gal mat developedover thesoilsur-faceineachofthe treatn.'C:ntsweresubw.erged fora considerable

PAGE 52

AVERAGEDRYWEIGHTPERSEEDLING(g) ...,,.,.j':)C'i I1looo. .... oNo w o. .,. o en o. '" Io. ...., o. 00 o. '".... .o .... ........ .N .... '".... .,.....en.... '".... ....,....OJ o ;t,.,"!1<,..."'i1-'1,fj"'J),ril,... til !10 o0 :::l(1',... 'j"ill"1o onr,"(l..rt" (,i-'""'i" I1l ,.,.JQ::rrtVI o ....CJl(lJ I1l (l..,.,."fJlHOISTHELLDiU\mEDSATURATEDALTEl$ATED T',,'O 1,IEEKSDRAINED-SUUHERGED ALTERNATEDTHREEDAYS 0rJ,wED-SUBMERGEDEl o >-ltiltilHl'1til..,.f;;til"l

PAGE 53

aIT':OlUlt of time; in SOr.1.e casesthealgal mat.alr.'OstcoI:lpletely coveredtheseedlings.Afterten m:mths only tim seedlingsremainedinthetreatmentthatwaScontinuouslysubmerged.Intheothertwosubmergedtreatmentsnosurvivingseedlingscouldbedetected.Twomonthslater,orafteroneyearoftotalsubmergence,onlyoneseedling, ,,,hich wasalmost completely coveredwithalgae,remained.Theseedlingsthatwereinthepotsthatwereremovedfrom submergence aftersixmonthsappearedtoresumenormal grmvth. 43

PAGE 54

THE RESPONSEOF NELALE:UC/\ TO .AL'lI\IDBIC SOILCONDITIONSFromtheresultsofthepreviousexperiment,itseemslikelythatMelaleucacangrowatleastequallyaswellundersaturatedorfloodedcxmditionsasunder r.toist, well-drainedconditions;however,observa-tionsinthefieldseemtoindicatethatMelaleucaprefersseasonallyfloodedsitesoverthosewhicharecontinuouslyflooded.Thissuggeststhatlong term floodingmaybedetrimentaltoMelaleucagrowth,oratleastit may beunabletocompetewithcypressoncontinuously flood.ed sitesandthatlowdissolvedoxygen levels inthewatermaybeadeterminingfactor.Generally,inaquaticecosystems,theamountofdeadorganicmatterpresenthasastrongaffectontheamountanddistributionofdissolvedoxygen(Ruttner,1963).Firesduringsea-sonaldroughtscanconsumethemuckandpeat,therebyreducingtheamountofoxidizableorganicmatterinthewaterwhenthesiteisfloodedandprobablyincreasinglightintensitiesforphotosynthesisbyeliminatingsomeofthevegetationshadingasite.Drainageaeratesorganicsoilswhichincreasestheiroxidation.Thissuggeststhatdissolvedoxygenlevelsmaybehigherinfloodwatersonsitesthatarerelativelyopen,arefloodedforshortperiods,andhavebeenIrecentlyburned.ObjectivesThefollowing wassetupinan attep-pt tofindoutwhetherMelaleuca,atleastintheshortrun,is adverselyaffected 44

PAGE 55

45anaerobicsoil caused by low oxygen levelsinflood waters. Ifso,thiswouldsuggest t...1.at thecontinuinggrowthof onasitemaybedependentonfire themaintenanceofrelativelyshortperiodsofflooding.ProcedureTenMelaleucaseedlingsweregrownfromseedsinthegreenhouse.They"eredividedrandomlyinto t-"o groupsandeachgroupwasplantedina19-1iterglazed croc.'<. Thetwo croc.'
PAGE 56

TABLE3.Seedlinggrowthunderaeratedand soilconditions.TREATMENTNON-AERATEDAERATEDInitialHeightafterDiff.InitialHeightafterDift.Height(em) 34days(em)(em)Height(em)34days(em)(em)40.084.244.426.070.844.835.578.543.2 47.8101.854.034.981.046.144.188.144.035.178.643.532.658.225.653.588.434.9 39.879.039.2 39.882.143.438.179.641.5 ""0"\

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47thatthetreatmentsdidaffect heightindicated thattherewas no significantdifferencebetweenthe height gra;th ofthetwoexperiments.Thetreesinthenonaeratedtreatmentproducedamassiveamountofadventitiousrootsbetweenthewater level andthesoil,andtherootswithinthesoilpenetratedonly8 em. Thesoil,whenremoved,producedthedistinctivesmellofhydrogensulfide,indicatingthatitwasanaerobic.Rootsintheaeratedtreatmentextendedtothebottomofthecrock,indicatingthattheairsuppliedatthesurfacewasabletodiffuseintothesoil.Onlya few adventitiousrootswereproduced.Rootbiomassmeasurementswerenottakenduetoproblemsinextractingtherootsfromthesoil. However,there wasnodistinctivedifferencesinrootappearance.

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FIELDSTUDIESAlthoughgreenhouseandlaboratoryexperimentscanprovidesomeindicationofwhattoexpectunderfieldconditions,oneishesitanttodrawconclusionsbasedontheseresultsalone.Theimportantquestionstill underwhatfieldconditionswillMelaleucasuccessfullyinvadeasite?siteconditionsfavorabletoMelaleucainvasionwerestudiedbyMeskimen(1962).Heseededseveralsiteshavingdifferentsoilcharacteristicsandsupportingvariousvegetationtypes.Inthegreenhouse,hesimultaneouslyran germination testsonsoilsamplescollectedateachsite.HisresultsindicatedthatMelaleucadidwellonacid san&.l soils,whilealkaline narl soilsdidnotgenerallyinducegermination.GoodgerminationwasobtainedonsoilsalreadysupportingMelaleuca,indicatingthatthelargestandsinLee arenotonlytheresultoftheinitialintroductiontherebutalsoaresponseto favor-:l.ble soilconditions.Ochopeemarlsoilsdidnotgenerallyinducegermination,eventhoughsomeofthesitesalreadysupportedMelaleuca plantations. Thisindicatedthatevenonunfavorablesites,conditionsat maybe conducive to Thisisapparent when oneconsidersthat Heskimen (1962)pointedoutthatby1960a14-year-old growingonOchopeemarlnear roe Station inCollier Countyhadnot produced any reproduction.Sincethenithasreproducedand spread several Di12strow theoriginalplanta-tion. This maybe anin:.licatio:lthat soil characteristics arenotas48

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significant as previouslybelievedandthat P.lOistL1reconditionspresent atthe tima ofseedrelease a.nd duringinitial establishment maybeatleastas important.Meskimen (1962)concludedthathisresultssupportedthehypothesisthatgerminationandestablishmentmaybecontrolledbysoilpHanditsramifications,andthatmuchofSouthFlorida'swetlandsthatareunderlainbyalkalinemarlsarenot assusceptible toMelaleucainvasionasarethoseareasunderlainbyacidsands.Thepresent distribution anddirectionofspreadofHelaleucainSouthFloridaarealongtheeastandwest coasts, and aroundthe areas oforiginalintroduction.Ithasbeengenerally assu..'1led thatthesedistributionpatternsareanexpressionofprevailing -".;ir,:Js anddrainagepatternsthatactasseeddisseminators. Thisexplar..ation has ledtotheconclusion Llcat the vastinla."d areasofSouthFloridaarerelativelyfreeof duetothepaucityof seed reachingtheseareasandthatit is onlya matter oftimebeforel1elaleuca \,ill becomeaconspicuouspartoftheseinland ecosystems. Thusthet.. "o predominantexplanationsforthepresentdistribu-tionandfuturespreadofHelaleucaare(1) Nelaleuca,;ill belargely limited totheeastandwestcoastsbydifferencesinthe soil teristics,and{2}thepresentdistributionanddirectionofspreadarecontrolledbybiogeographicalinfluences,includingthe availability ofaseedsource. Objectives Itseemslmlikely thatwouldbe topractic3l1yallsitesin SouthFlorida.there are sites thathave ::ee:l

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50 susceptibleto Melaleucainvasion thanothers.Ifeelthatcer-taindefinablesiteconditions, Doth biologicalandphysical,areprerequisitesforMelaleucaestablishment,andthatMelaleucawillbelargelylimitedtothesesitesinSouthFlorida.FieldstudiesweresetuptodeterminewhattypesofsitesaresuitableforsuccessfulHelaleucaestablishmentandtodelineatesomeoftheimportantparametersthatinfluencegerminationandprovideforsubsequentgrowthand su....-"ivaL Thefactorsconsideredwerethetimeofyearof,seedrelease,soil rraisture theinfluenceofwaterlevelandhydroperiod,theeffectofsitedisturbanceandlandusehistory,andvegetationtype.ProcedureInitiallysixstudysiteswereselected,onein ofthefol low'ing vegetationtypes:pineflatwoods,mixedhar&vood--cypressI dwarf cypress,sawgrasswetprairie,mature cypress, andmangrove.FoursiteswereestablishedinJa.'1uary1974.Studies'-IerebeguninthematurecypressforestandsawgrasssitesinFebruary. moresiteswerelaterestablishedasconditionsandpreliminaryresultspresented new problems.Amixed hard\wod--cypress siteburnedinApril,soaplot \-'as establishedtherein Hay..An eighthsitewasestablishedinlateJuly1974aswaterconditionsontheothersitesindicatedthatthewaterlevelsonthesesites were probablynot alteredbydrainage This neH siteI"'as established ina \.;ell-drained cypressstandwithtwodrainage locatedwithin200moftheplot, one to theandtile to th8west. Plot numbers,oflocation, vegetationtype,

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51andgeneralcharacteristicsofthefieldplotsarelistedinTable4.Figure11showsthelocationoftheeightsites.Ateachsitea20 m by20 m plot VIasarbitrarily chosenandmarkedoffwithanorth-south,east-westorientation.An attempt wasmadetolayouttheplotsoveranareaexhibitingvaryingdegreesof=ver,vegetationchanges,andtopographythatappeared andrepresentativeofconditionsfoundinSouthernFlorida.Theplotsweredividedinto0.2msubplots,eachameterapart,withfivesubplotschosenforeachmonthofthestudy.Eachofthefivesubplotswereseededrronthlywith1gofseed.Theseedwascollectedfromalargeuniform Nela leucastandnearEstero,Lee County, andwasperiodicallytestedforviability.Othersubplotsonthesameplotswererandomlyselectedfortheplantingofgreenhouse-grownseedlings. The originalplan was toseed5subplotsoneachplotapproximatelyonceamonthforat least ayearandrecordgermination a'1d survival 'Lie longesttime beto;'ieen seedingswas57days,theshortestwas23days,andtheaveragewas34days.Plantingswerenotcarriedoutonamonthlybasis.Itwasintendedtogetatleast5seedlingsestablishedassoonaspossibleon plotandobservetheir grm.n:h through year.Thefirst pla'1ting didnottakeplaceuntil Narch 31.This',raswellintothedryseasonandpracticallyalloftheseedlingsdid not survivetheirfirst month. Asecondplanting ,"vasmade on t1ay25. Atthis time thesoilonallsites was moist,duetoseveralearlywet-season Nevertheless,onlyabouthalf of theseedlings survi,/ed the plar.t.ing. Fivesubplots on eachplot \'lere again pla::'lted in J:lly,""h'3t1rr.ost ofthesites 'dere flooded.Inthiscase,survival -,"las100-0'".:tItertilefi:cstfctOnth. Also,plots t'2,#3,and the newlyes"tablishedplo-:=.#8 t.'Jere pla..1ted in August\'lith both

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TABLE 4.Studyplotlocations, dates of establishment,and descriptions. DAT!': PLOTESTABLISHED1 January 18 2 January 19VEGETATIONTYPELongleafpineflatwood Hixed hardwood--cypressswamp(notburnedwithintwoyears)LOCATIONEstero,LeeCounty.SouthofAlligatorAlleyontheeastsideofthe Fahka hatcheeStrand.CHARACTERISTICSSandywell-drainedsoil.Shallowsandypeatsoil;drainedindryseasonwith15-35emofsurface water duringthewetseason.3 Hay 25 Hixed hardwood--cypress swamp (burnedinApril1974)Adjacenttothesouthsideofplot jf 2 Same asplot#2exceptslightlyhighertopographywith5-25emofsurfacewaterinthewetseason.45 GJanuary 19 Dwarf cypress February lG wetprairie Pebruary16Mature cypressstrandNorthoftheDadeCollierTrainingJetportin eastern CollierCounty.Onemile west of40 Nile Bendinwestern Delue County.Threemiles east ofMonroeStationinCollierCounty.Shallow sandy marlsoil;drainedinthedry season, 5-25emof surfacewater inthewetseason.Shallow marl soiloverlimestone; drained inthedry season, 10-20emofstanding water during thewet.senson. Mucktopeatsoil; drained inthedryseason,20-70emofsurfacewaterduringthewetseason. 1,' 7 8January 19August12Whitemangrove--Spar tinaswamp DrainedcypressFivemilesNWofCarnestowninCollierCounty. Pour miles NE ofGolden Celte inCollierCounty. Brownfibrouspeat;saturatedinthedryseason,10-30emofsurfacewaterduringthewetseason.Deepsandysoils;artificiallywell drained throughouttheyear. V1'"

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Figure11.MapofsouthwestFlorida showing thelocationofthestudysites.1Longleafpineflatwood2Mixedhardwood--cypressforest3Burned mixedhardwood--cypressforest4Dwarfcypressforest5Wetprairie6Maturecypressforest7Mangrove8Drainedcypressforest

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54BigCypressIIIIII II __ -i l__CollierCo.iI <: FortMyersCanals Roads -

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55a !-te laleucaandacypressseedlingon eac..1. 0fthefivesubplots,inordertoobtainacomparisonofcypress a..'1d[!elaleuca seedling grop,Hth undernearlyidenticalfieldconditions.ThecypressseedlingswereobtainedinFebruaryfromthe d,;arf cypresssiteandkeptinthegreenhouseuntiltheywererepla!1tedinthefield.Onlythreesiteswereselectedforplantingbecauseoflackofcypressseedlings.Allseedlingswereplantedbare-root,thesoilbeingwashedoffjustpriortoplanting.Initialheightandmonthlygrowthin=ementswererecordedandgrowthresponseswerenoted.Duringeachvisitonesurfacesoilsamplewas forsoilmoisturedetermination.Thiswasbynomeansarepresentativesample,butthetimelimitationsofweekend,tripsprecludedthedesignofamoresophisticated sa",-npling procedure;nevertheless, aT} indicationof reonthly changeswasobtained.Duringthe Harch trip3.8emdiameter g:llvanized ironpipes '>',ere drivenintothegroundforwaterlevel deterTItinations. Anattemptwasmadetoplaceeachpipeasclosetothecenteroftheplotaspossible,butwherebedrockwasnearthesurface,severalboringsweremadetosetthepipeasdeepaspossible.Nopipewasplacedeitheronsite5(sawgrass),duetotheshallownessofthesoil,oronsite3(burned),duetoitsproximitytosite2whereonepipeservedbothsites. Mon thlywaterlevelchangeswererecorded.InJulyandAugustweeklymeasurements \-Teremade. depth neasure:r..entsi.o,Jeremade ateachoftheseededorplanted on the floodedsitestogetan idea. ofthe topograpnicchangese2.ch plot.Startingin July,"';!'Lennostor the ploes flooded, ",,eeklydissolved oxygen [t2i1Su:ce:I.ents';Cr.2iJace of thesurfaceHacer usinga

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56modified reethod. The were taken fromtheplotcenters.Again,onlyonesample \vas takenpersiteeachweek,andthetimeofdaywhenthesamplewastakenvaried,sothedatacanonlybeconsideredanindicationofthedissolvedoxygencontentsunder .,hich seedlingestablishmentwasattempted.Inadditiontoaqualitativedescriptionofthevegetationoneachsite,forty1m 2subplots .,ere randomlyselected,andtheterrestrialandrootedaquaticplantspeciesthatoccurredoneachsubplot .,ere recorded.ResultsSitedescriptionsThelongleafpine flao;ood siteislocatedjustsouthoftheKoreshanStateParkinEstero,LeeCounty.ItisdominatedbyPinuspalustris t1ill (longleafpine), Sprenoa repensHook.f.(sawpalmetto) BefariaracemosaVent.(tarflower)(seeFig.12).Melaleucaisabundantaroundthesite a..'1d therehavebeennumerousseedcropsreleasedinthevicinity.However,noMelaleucaisgrowingonthesiteexceptwherethereareobviousdepressionsinthetopography..The20rnby20mplotisfreeof The predorninaTlt speciesonthissitearelistedinTable5. Tne soilisawell-draineddeep probablylowinfertility.Monthlysoilmoisture presentedinFigure13illustratethat pea.1<.moisturelevels \'lere rcac..'ledduring at.hreemonthperiod betw"een t.layand July.The restofthe yearthe moisturelevels \vere 10(.'/andthesoi1 surfacedr}'.

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Figure12.Longleafpineflatwoodsite.57

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TABLE5.Listofcommonplantsonthelongleafpineflatwoodsiteandtheirabundanceexpressedasapercentofthetotalnumberofsampleplotswheretheyoccurred.58WOODYPLANTSBefariaracemosaSerenoarepensPinuspalustrisIlexglabraQuercusmyrtifoliaHERBACEOUSPLANTSHypericumbrachyphyl1umAndropogon capillioes AristidaspiciformisAristidatenuspicaLachnanthescarolinianaABUNDANCE97.582.57.57.5 7.545.026.512.5 10.05.0

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59THISSITE WAS NOTFLOODED9080 40 ...'"030:<:H02'" 1JFMAMJ JA5o N DFigure13. Monthly soilmois tUNchangesam! lengthoffloodingonthe pineflatwoodsite.

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60Thewaterlevel(showninFig.14forallsites)atthissitewassubsurfaceexceptforaone-weekperiodinJulywhenheavyrainsoccurredinLeeCountyandthewaterlevelrosetothesurface,causing ?ome puddling.ThelowestwatertablerecordingwasinlateAprilwhenitdroppedto172cmbelowthesurface.Thehighestreadingof2.0emofsurfacewaterwasrecordedinJuly.Thissite,withthepossibleexceptionofthedrainedcypressforestsite,hadthelowestaveragewaterlevelandtheshortestperiodoffloodingofanyofthestudyareas.Themixedhardwood--cypressforestsiteislocatedjustsouthofAlligatorAlley,alongthewestedgeoftheFahkahatcheeStrandinCollierCounty.ItisdominatedbyTaxodiumascendens(pondcypress),FraxinuscarolinianaMill.(popash),andAcerrubrumL.(redmaple).Thesiteapparentlyburnedafewyearsagoandmanyhardwoodsnagsarenowpresent.Thelossofthesetreeshavemadethecanopyrelativelyopenandthesoilisdenselycoveredwithherbaceousplants(seeFig.15).ThemoreabundantspeciesarelistedinTable6.NoMelaleucawaslocatedontheplotornearthesite.Theclosestobserved treeswereatleast15kmaway.Approximately1mofsandypeatsoiloverlieslimestonebedrock.Thetopographychangefromhightolowpointwithintheplotis21cm.Soilmoisturemeasurements,asshowninFigure16,indicatethatrelativelyhighmoisturewaspresentinthesoilduring"JanuaryandFebru-ary.Itwasreducedin Harch andApril and thesoilsurfacebecame dry. Earlywetseasonrainstorms causedthe soilmoisturetoincreaseinMay.ByJune,thesite \,asflood..:;d. levelonthis sitefl:"lc:tuatedfro=n 1mbelo",, Lhe surface

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Figure14.Waterlevelchangesontheeightstudyplots.0 0 Longleafpineflatwood "". \/Mixedhardwood--cypressforest /',/\ Burned mixedhardwood--cypressforest 8il Dwarfcypressforest A..Wet prairie0 0Hatureforestcypress Q0 Mangrove D" Drainedcypressforest

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62 t.:l....o >o zltJUl ..J ::>.., I III I z I :::> I ..,, IIIIIt >I :I> I ::i I,IIIII II !!?NI131131Ht:A

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63Figure15.Mixedhardwood--cypressforestsite.

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64TABLE6.Listofcommonplantsonthemixedhardwood--cypressforestsiteandtheirabundanceexpressedasapercentofthetotalnumberofsampleplotswheretheyoccurred.WOODYPLANTSABUNDANCE Taxodiumascendens(trees)Taxodiumascendens(seedlings)AcerrubrumsalixcarolinianaBaccharishalimifoliaFraxinuscarolinianaMyricaceriferaFicusaureaHERBACEOUS PLAl'lTS serrulatumMikaniabatatifoliaLudwiqiarepensBoehmeriacylindricaPolygonumhydropiperoidesCladium CyperushaspenPonted2ria lanceolata 32.55.025.0 22.510.02.52.52.590.065.042.532.522.512.510.07.5

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65Figure16.Monthlysoilmoisture changesand lengthoffloodingonthe mixed hardwood--cypress site.

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66duringthedryseasontoarelatively levelof20-25 emabove thesurfaceinJune,July,andAugust.It todropoffagaininSeptember.Bylate Novel1'ber approximatelythree-fourthsoftheplotwasstillflooded,makingthehydroperiodaboutsixmonthslong.DissolvedoxygenreadingsforallsitesaregiveninTable7.Thedissolvedoxygencontentofthefloodwatersatthemixedhardwood--cypressforestsitewasfairlylow.Thegreatestamountrecordedwas2.56 ppm, takenfromanafternoonsample.Theothermeasurementswere ta'<.en atmidmorningandthismayaccountforthelowervalues.Theburnedmixed-hardwood-cypressforestplotislocatedadjacenttothepreviousplot,withinthesamevegetationtype.Thisplot ,.,as establishedafterafirehadburneduptotheedgeoftheotherploton Harch 31.Thispresentedanopportunitytoobservedifferencesbetweenarecentlyburnedsiteandonethathadhadafewyearstorecover.Thefirecompletelyeliminatedthegroundcoverand/orkilledmanyofthe hara.mods.Tne plot was establishedon Nay 25,after a fewdaysofrain,andonlya fS'" grassesandherbshadsprouted.Thepredominantwoodyvegetationontheplotwaspondcypress(Fig.17).AlistoftheotherabundantspeciesaregiveninTable8.Nosoilsampleswere ta'
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TABLE7.Dissolvedoxygenmeasurementstakenonfloodedstudysites. HARJ);,/OOD--CYPRESS FORESTSITEWETPRAIRIESITEDissolvedOxygenDissolvedOxygen Date TimeContentofWater(ppm)DateTimeContentofWater(ppm)llugust1015002.09August1116009.49 1811001.08August1816008.17 J-\ugu.st 2410000.65August2414003.17 1\ugust 2911001.32August3010003.74 October 1515002.56October1709003.15 Novcl:!ber 3014002.76November3012006.54 i>1IXEDHMill\'IOOD--CYPRESSDilteTimeAugust 101500 August 181100 August 241000 August 291100October151500FOREST(BURNED)SITEDissolvedOxygencontentofWater(ppm)2.091.080.872.424.14DateAugust9August18August24August31October17November30MATURECYPRESSTime1500 1500130016001000 1300FORESTSITEDissolvedOxygenContentofWater(ppm)3.641.510.871.321.381.09Time1400100009001500 14001100DateAugust9August18August24 l\uqUDt20 October16 November 30 DI'/ARF CYPRESSSITEDissolvedOxygenContentof I'/ater 4.451.942.62 2.99 2.562.67(ppm)DateAugust18August24August29October17 MlINGROVE Time1400 1200 16001200SITEDissolvedOxygenContentofWater1.720.655.97 1.97 (ppm) C\"

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68Figure17.Burned mixedhardwood--cypressforestsite.

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TABLE8.Listof plantsontheburnednixedhardwood--cypressforestsiteandtheirabundanceexpressedasapercentofthetotal of pointswherethey 69WOODYPLANTS ascendens Sabal pallnetto BaccharishalimifoliaPerseaborboniaSalixcaroliniana rubrumCephalanthusoccidentalisHERBACEOUSPLANTSBlechnumserrulatumSaccioleoisstriataNymphaeaodorata hvdrooiperoidesHyptisalataPontederia DiodeavirginianaMikaniabatatifoliaCannaf1accidaBoehmeria cvlindrica SolidagostrictaHydroles Melothria ABUNDANCE15.07.52.50.5 0.50.5 0.572.540.025.022.517.512.510.07.5 7.57.55.02.52.5 2.5

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70thedry season. BylateNovemberthewaterlevelwasagainsubsurfaceandthesoilwassoggy.Thedissolved oxygen measurementsaveragedslightlyhigherherethanontheadjacentplot(samplesweretakenatthesametime).Thiswaspossiblyduetothemoreopencanopyandsparsergroundcover,whichmayhaveresultedinagreateramountofalgalphotosynthesisinthewater.ThedwarfcypressforestsiteislocatedjustnorthoftheCollierDadeTrainingJetportineasternCollierCounty.Thevegetationispredominantlywidelyscattereddwarf(pond)cypress(Taxodiumascendens)withaherbaceousgroundcover(Fig.18).Theplotincludespartofasmallcypressdome.NoMelaleucawerelocatedontheplot;theclosestindividualswerelocatedalongadisturbedroadsideabout2kmsouthoftheplot.CommonspeciesontheplotarelistedinTable9.ThesoilisanOchopeefinesandymarlthatrangesindepthfromonlyafewcentimeterstooverameter.Thetopographychangewithintheplotis22em.Muchofthesoiliscoveredwithathickalgalmat.Duringthedryseasonasit separatedfromthesoilsurfacethematdriedout.Seedlingswhichgerminatedon t.his matweresubjecttodessicationasthisprocessoccurred.Onsitesinwhichthematwasburnedduringthedryseason, the chancesofsuccessful germina tionwouldbeenhanced.Burningwouldeliminatethe mat, whichactsas effectivebarrierbetween the Melaleucaseedandmineralsoil.Soilmoisturelevels presented in ?igure 19showthat noisture contentdroppedsteadilyfrom January, its levelinAprilwhen the soilsurface algal ma.t '..Jeredry. The \.-later table (Fig. 14) dropped to90 era belo'.]thesurface during late Narch, April,and earl2-:1J21" Thiscorrespondedtothe

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Figure18.Dwarfcypressforestsite.71

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TABLE9.Listofcommonplantsonthedwarfcypressforestsiteandtheirabundanceexpressedasapercentofthetotalnumberofsampleplotswheretheyoccurred.WOODYPLANTSABUNDANCETaxodiumascendens(trees)45.072Taxodiumascendens(seedlings)MyricaceriferaChrysobalanusicacoFicusaureaHERBACEOUS Cladiumjamaicensis virgatumPaspalurnmonstachyurnProserpinacapalustrisCassythafiliformisNymphaeaodorataStillingiasylvaticaBacopacaroliniana35.02.5 2.52.567.545.025.022.57.5 7.55.02.5

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9080 .t' 50 '" 40 g;!-' 30c :<: 20c '" 10FLOODED 0-----------.<;G-... 73JFMA M JFigure19.Monthlysoil mois:urechanges and length of floodingon the dvarf cypressforestsite.

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74period when boththesoilsurfaceandalgalmatwere dry. Duringthewetseasonthesurfacewaterlevelfluctuatedbetween25and30 en andbeganto.recedeinearly Theperiodoffloodingwasfivetosixmonthslong.Dissolvedoxygencontents(Table7)werehigherthanthoserecordedonthepreviousplots. 1"ne highestmeasurementwas4.45ppmrecordedat2:00PM.Othermeasurementstakenintheafternoonwereatleast1.50ppmlessthanthis.Ifthehigherlevelsaresignificanttheycanprobablybeattributedtotheopennessofthecypressforestandtheresultingphotosynthesisofthesubmergedalgalmat.ThewetprairiesiteislocatedjustsouthofU.S.41,1.5kmnorthwestofForty-mileBendin Dade.County.ThedominantspeciesisCladiumjamaicensis(sawgrass).Nowoodyvegetationwaslocatedontheplot(Fig.20).OthercommonspeciesarelistedinTable10.Thesoilisamarl(probablyoftheOchopeeseries)withanaveragedepthof15to30erntolimestonebedrock.Thetopographychangefromthehightolowpointwithintheplotis8 ern.SoilmoisturemeasurementspresentedinFigure21 shmv thattherewasconsiderablemoisturestillpresentinthesoilin April,andMay,butdueto fine textureofthisclaysoil,themoisturemaynothavebeenreadilyavailabletoseeds.Water table depthsduringthedryseasonwerenotobtainablebecausetheshallownessofthesoilmadeitimpossibletodriveapipeintothe grOlliid. Thewater level after Jur.e isillustratedin =igure 14.The surface water averagedabout 20cnindepthduringthe wet season.Thissiteisprobablyfloodedlongerthananyofthe sevensites due. tot.he rele2.se of water intotheEvergladeSNational

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Figure200 Wet prairie site.75

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76TABLE10.Listofcornmanplantsonthe .. etprairiesiteandtheirabundanceexpressedasapercentofthetotalnumberofsampleplotswheretheyoccurred.HERBACEOUS PLANTS CladiurnjamaicensisRhynchosporatracyiUtriculariabifloraMuhlenbergiacapillaris BacopacarolinianaSagittariagramineaEleochariscellulosa ABUNDh"lCE 97.587.572.525.0 5,0 2.5 2.5

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77FLOODED e09080 ....cto-; 60 >..0 50 '" 40 ::>E-lttl H300 ;:c::l 200 ttl 100JFMA H J JAS0ND HONTH Figure21.Monthlysoilmoisturechangesandlengthoffloodingonthewetprairiesite.

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78ParkfromConservation Area 3.Thistendstomaintainhighwaterlevelsthroughthefallinthisparticulararea.Asof Novelt'ber 30thissitewasstillflooded \;it.l> 19 em ofwater.Dissolved oxygen neasurements(Table7)werethehighestrecordedonanyplot.Insomecasesthesurfacewaterwassaturated,asindicatedbylateafternoonreadingsashighas9.49and8.17ppm.TwoofthelowerreadingswererecordedinthemorningwhileathirdwastakenonacloudYday.Presumablythehighdissolvedoxygenlevelsresultedfromthephotosynthesisofthealgalmat.Thematurecypressforestsiteislocatedwithinacypressstrandapproximately5kmeastofMonroeStationandsouthofu.S.41inCollierCounty..ThepredominantwoodyspeciesareTaxodiumascendens,AnnonaglabraL.(pondapple).andFraxinuscaroliniana.ThemoreabundantspeciesarelistedinTable11.Thestrandischaracterizedbyatalloverstoryof nature cypresstrees "'lith ascattered under storyof harcrNoods, a fer..,reaa.'1ing intothe Im.,er canopy.T'nestrandfollowsalongdepressionrunninginanortheast-southwestdirectiqnandaccountsforaconsiderable an'Dunt of \'laterflm., fromtheBig Cypress Watershed.Theplotislocatedattheedgeofapondinthecenterofthestrand.Partoftheplotextendsinto theshallm;er portionofthepond fullsunlightisavailable, \-lhile mostof the plotisin denseshade (Fig.22).Thesoilis varicble in depth andoonsistsofa muc
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79TABLE11.Listofcommonplantsonthematurecypressforestsiteandtheirabundanceexpressedasapercentofthetotalnumberofsampleplotswheretheyoccurred.WOODYPLANTSFraxinuscarolinianaAnnonaglabraFicusaureaTaxodiumascendensSabalpalmettoChrysobalanusicacoHERBACEOUSPLANTSLudwigiarepensNymphaeaodorataBlechnum AsclepiasincarnataThaliageniculataRhusradicansMikaniabatatifoliaHydrocotyle ProserpinacapalustrisABUNDANCE7.57.52.52.52.52.527.520.010.07.52.52.52.52.52.5

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Figure22.Maturecypressforestsite.80

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FLOODED I819080 '"' 70 .,.r:""Ol 60 :0>-.c 50 ....'" 40 E-<'"H 300 :>::H 200 '" 100JF11A M JJAS MONTIl oNDFigure23. Honthly soil changes a11d length of flooding onthe mature cypressforestsite.

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82The "ater level (=ig. 14)duringthedryseasondroppedbelo,'thedepthofthepipe (75cm). Thesurfacewaterrosetoabout58 em duringthe summer monthsandthenbegantodropoffinSeptember.Bylate Novell'ber mostofthesitewasstillfloodedwith35emofstandingwa-teratthecenter.oftheplot,givingmostoftheplotatleastasix-monthhydroperiod.Dissolvedoxygencontents(Table7)werequitelow.Thehighestmeasurementwas3.64ppm,with rrost ofthemeasurementstakeninthelateafternoonwhendissolvedoxygenlevelswouldbeex-pectedtobeattheirhighest.Themangrovesiteislocatedabout7kmnorthwestofCarnestown,alongU.s.41inCollierCounty.Thedominantspecies(Table12)arewhitemangrove(LagunculariaracemosaGaertu.f.)andopenmarshesofSpartinaspartinae,andSalicorniabigelovii.Itischaracterizedbydensepatchesofwhitemangrovethatabruptlychangetoopensaltmarsh(Fig. 24). Shallo'H mal"lgrove creeksorestuariesmeanderthroughbothvegetationtypes.Thesoilisafibrous brmm peatthatheldenoughmoistureevenduringthedryseasonsothatwatercouldbesqueezedoutofit by hand.Thetopographychange "ithin thestudyplotis12.5em. Water levelchangesareillustratedinFigure14.Thewatertableremainedatornearthesurfaceduringthe drt seasonandthewaterwasprobablybrackish.Duringthe ',,,et seasonaninfluxoffresh ,.,ater wasreceivedfromthe Fa..."rt.'!
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TABLE12.Listofcommonplantsonthemangrovesiteandtheirabundanceexpressedasapercentofthesamplepointswheretheyoccurred.83 DY PLANTS LagunculariaracemosaHERBACEOUS PLANTS SalicorniabigeloviiSpartinaspartinaePaspalum vaginaturn. ABUNDANCE45.050.042.512.5

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Figure24.Mangrovesite. 84

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85Dissolved oxygenmeasurementsHere variable, l,vith theresults ra.:."1ging from0.65ppmto5.95 ppn. Thedrainedcypressforestsite,whichwasestablishedinAugust,islocatedabout8 kmnortheastofthe=mmunityofGoldenGateinwesternCollierCounty.Itisanartificiallywell-drainedsitecharacterizedbyarelativelyopenstandofpole-sizedcypresstrees(Fig.25).Nopineislocatedonthestudyplot,butthesiteareaincludesa patchwo:rk ofscatteredpine(Pinuselliotii)andcypressstandsdelineatedbyslightundulationsinthetopography.TheunderstoryonthestudyplotismostlygrassesandherbswhichincludemanyweedyspeciessuchasBaccharishalimifolia,Hypericumsp.,andFoeniculumvulgare.ThemoreabundantspeciesarelistedinTable13.Thesoilisadeepsandthatwasmoist(Fig.26)throughAugust,butbyOctoberthesurfacewasverydry.TheNovembersoilsample 'vas takenduringarainstormwhichaccountsfortheincrease Thewatertable(Fig.14) was nearthesurfaceatmid-summer,andforabriefperiodinAugust therewas puddledsurfacewater.Otherwise,theplotwaseffectivelydrainedthroughouttheyear.SeedingTrialsAccurateseedlingcounts froT seed so'lln onthestudyplotsweredifficultto duetothesmallsizeoftheseedlingsandthefactthatsiteconditions considerablyfrom visittovisitduetovegetation groHth,v.iater level c:1.anges I and insomecasesthe devclopI:'.ent ofanalgal raat that the seedlir.gs. Consequentlyan indLcated lossofseedlings actuall:::cmay resultedfrommyinabi-hilityto relocatea seedling 2.2:.d notactual Elortality. Onlyas the.

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Figure 25. Drainedcypressforestsite.86

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TABLE13.abundanceoccurred..Listofcommonplantsontheexpressedasapercentofthedrainedcypresssiteandsamplepointswherethey87their PLANTS TaxodiumascendensBaccharishalirnifoliaMyricaceriferaHERBACEOUS PLANTS mikaniodesChlorisneglectaPluchearaseaHyptisalataFoeniculumvulgareEupatoriumcapillifoliumCladiurnjamaicensisVitisaestivalisMikaniabatatifolia ABUNDANCE27.57.52.557.547.545.040.040.017.5 17.510.07.57.5

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THISSITEWASNOTFLOODEDI90 80 70 ....t::etJe: 60 ";..,,0 50 ...'" 40 :::>til H300 :>:..J H200 til 100JFMA M J MONTH J ASo N D88Figure26.Monthlysoilmoisture anelength offloodingonthedrainedcypressforestsite.

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89waterleveldropsandseedlingsgrowwillactualsurvivalbeknown.AsshowninTable14,seedlingswerenotobservedonthe pine flatwoodsiteuntilAugust5,whenfourseedlingswererecordedontwosubplotsthatwereseededinJuly.Apparentlynoneofthepreviouslysownseedremainedviableduringthedryseasontogerminatewhenmoisturerequirementsbecamefavorable.Aseedlingcrop we,.':cecorded onAugust31fromseedsownonAugust5,butbyOctoberallof i:hese seedlingshaddiedandonlyoneseedlingremainedfromthe .July1.1 seeding.AsofNovember28onlyoneseedlingthatgerminated seedsowninOctoberwasobservedontheentireplot.Theresultsoftheseedingsonthemixed hardwood--cypn,.'nsite aregiveninTable15.Theonlygerminationrecordedwas JanuaryandFebruarywhenthesoilwasmoist.Inthiscase a. totalof70seedlingswereobservedonatotaloffoursubplots.Allofthese ... erelosteitherduringthedryseason,inthesummer while thesitewasflooded,orinthefall ,"lhen thewaterleveldropped,.Theseedingresultsfortheburnedmixedhardwood--cypresssiteareshowninTable16.Twenty-eightseedlingswerecountedon,July12resultingfromthe Nay seeding.Losseswererecordedeachsucceedingmonth.ByOctober17onlytwooftheseseedlingsremained.Theheavyalgalbloom(whichmayhaveresultedfromnutrientsreleasedbythefire)madethesecountsunreliablebyobscuringthe Nogerminationoccurred underwaterstilisequent seedings.Bylate November thesite T,... asnolonger flo:Jded andseedgermination \-,as recorded 0::1 subplotsthathadbeen seeded as e3.rly asJuly12.Allfivesubplots s02ded inOctober and as manyas 850 seedlinss

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TABLE14.Resultsoffieldseedingsonthelongleafpinesite.DATEOFSEEDLINGCOUNTSJAN18FEB15MAR30APR26 HAY 24JUL14AUG5AUG31ocr17NOV28 JA..l\l 18Seeded0 0 0 0 0 0 0 0 0 FEB 15Seeded0 0 0 0 00 0 Will. 30Seeded0 0 0 0 0 0 0APR26Seeded0 0 0 0 0 0MAY24Seeded0 0 0 0 0DATE l'lHEN SEEDEDJUL14Seeded4 1 1 0AUG5Seeded700 0AUG31Seeded0 0ocr17Seeded1NOV28Seeded '" o

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TABLE15.Resultsoffieldseedingsonthemixedhardwood--cypressforestsite.DATEOFSEEDLINGCOUNTS JA..1\! 19FEB16MAR31 APR 27MAY25JUL12AUG4AUG29 ocr 17NOV30 Jl\.1\! 19ISeeded70000 00 00 0FEB16Seeded000000 00MAR31Seeded00000 0 0 APR 27Seeded0 00 0 00MAY25Seeded0 0 0 0 0DATE WHEN SEEDEDJUL12Seeded0 0 0 0AUG4Seeded0 0 0AUG29Seeded00 ocr 17Seeded0NOV30Seeded \!)r-

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TABLE 16.Resultsoffieldseedingsontheburnedmixedhardwood--cypressforestsite.DATEOFSEEDLINGCOUNTSMAY25 JUL 12AUG4AUG29OCT17NOV30MAY25DATEWIlENSEEDEDISeeded28189 21 JUL 12Seeded0 0 095AUG4Seeded0 05AUG29Seeded0 36OCT17Seeded1330NOV30Seeded enIV

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93wererecordedonasinglesubplot.ThisparticularsubplotwasverywetbutnotfloodedwhenitwasseededinOctober.Theresultsoftheseedingtrialsonthe &varf cypressforestsitearegivaninTable17.SeedlingswererecordedfromboththeJanuaryandFebruaryseedings;however,alloftheseedlingsdiedduringthedryseason.NofurthergerminationwasrecordeduntilOctober16,whensixseedlingswerefoundgrowingononeofthesubplotsthatwasseededattheendofAugust.Thisparticularsubplotislocatedontheedgeofthe20mby20mplotwherethetopographyishighest;consequently,aswaterleve15begantodropthissubplot 'vas oneofthefirsttobeexposed. "men thissubplotwasseededinAugustitwascoveredwith5 emofwater.Whenthissubplot was monitoredonOctober16,thisparticularsubplotwasnolongerflooded.Thesoilwas andtheseedlingsweregrowingonthewetalgallayer.Itisnotknownhowsoonaftertheseedingthewaterrecededoriftheseeds germinated OnNovember30,215seedlingswererecordedonatotalof four ofthefivesubplotsseededinOctober.Twoofthesesubplotswerestillflooded.OnehundredandfourteenseedlingswerecountedonfoursubplotsthatwereseededasearlyasAugust28.Theresultsoftheseedingtrialson Lhewet prairiesiteareshoftlninTable18.In narc"", 19seedlings recordedfromtheseeds inFebruary.In r!arch thesoil Has soggy \
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TABLE17.Resultsoffieldseedingsonthedwarf cypress forestsite.DATEOFSEEDLINGCOUNTS JA.'l 19FEB16 BAR 31APR27 HAY 25JUL12AUG3AUG28OCT16NOV30JAN19iSeeded1801200 0 0 0 0 0 0FEB16Seeded420 0 0 0 0 0 0 HAR 31Seeded0 0 0 0 0 0 0 APR27Seeded0 0 0 0 0 0 HAY 25Seeded0 0 0 0 0DATEWHENSEEDEDJUL12Seeded0 0 0 0AUG3Seeded0 0 3AUG28Seeded6114OCT16Seeded215NOV30Seeded '!l"

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TABLE18.Resultsoffieldseedingsonthewetprairiesite.DATEOFSEEDLINGCOUNTSFEB16MAR31APR27MAY25JUL12AUG5AUG30OCT17NOV30FEB16 Dle ISeeded190 0 0 0 0 0 0 MAR 31Seeded0 0 0 0 0 0 0APR27Seeded0 0 0 0 0 0MAY25Seeded0 0 0 0 0 rEWI-lENSEEDEDJUL12Seeded0 0 0 0 AUG 5Seeded0 0 0AUG30Seeded0 0OCT17Seeded0NOV30Seeded '"lJ1

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96inTable19.Seedlings\ .... ere in Harc..h fromseed inFeb.ruary.Amonthlaterthesoilsurfacewasstillmoist,butnoneofthe75seedlingscouldberelocated.Between March and alushgrowthofherbaceousplantsdevelopedontheforestfloor,particularlyinthemoreopenpartoftheplot.PresumablytheHelaleucaseedlingscouldnotcompetewiththeserapidlygrowingplants.Nofurthergerminationwasre=rdedeitherduringthedryseasonorwhilethesitewasflooded.Therewasanoticeablewater flO'.. throughthisplotduringthewetseason;thisflowwouldhavebeencapableoffloatingseedsoutoftheplotiftheyhadbeendirectlyonthesurface.Therefore,theseeds \'lere presoakedfor24hoursbefore sO\oJing, enablingthemtobeplaceddirectlyonthesoilsurfaceunderthewater.Ontheotherfloodedplotsthewaterwasconsiderablyshallowerwithnonoticeableflow,sotheseedcouldbe on the surface.Then,byagitatingthewaterbyhandtheseedswould sip_,<. TheseedingresultsforthemangrovesiteareshowninTable20.Nogerminationwasrecordedonthisplotat timeduringtheyear.TheresultsoftheseedingtrialsonthedrainedcypressforestsitearegiveninTable21.OnAugust28atotalof280individualswerereoordedfromthefivesubplots.ThesegerminatedfromtheAugust12seeding.ByOctober15,onlyeightoftheseseedlingsremained alive;manyoftheotherswerefoundinadessicatedstate.Fiveotherseedlings wererecordedin Octoberfrom-theAugust28seeding; hm-lever, inlate no seedling3remained ontheplot.

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TABLE19.Resultsoffieldseedingsonthe cypressforestsite.DATE OFSEEDLINGCOUNTSFEB16MAR31APR27MAY25JUL12AUG3AUG31OCT17NOV30ISeeded75 000000 0MAR31Seeded000 00 00APR27Seeded00 0 00 0MAY25Seeded0 000 0 m\'jlSN SEEDEDJUL12Seeded0 00 0AUG4Seeded0 00AUG31Seeded00OCT17Seeded0NOV30SeededDA' FEB 16 \D..,

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TABLE20.Resultsoffieldseedingsonthemangrovesite.DATE OFSEEDLINGCOUNTS JA.'l 19FEB16MAR31APR 27MAY25JUL14AUG9AUG29OCT17NOV30JAN19ISeeded0 0000 0000FEB16Seeded0 000 0 0 0 0 31Seeded0 0 0 0 00 0APR27Seeded000 0 00DATEWI-lENSEEDEDMAY25Seeded0 0 0 00JUL14Seeded0000AUG9Seeded00 0AUG29Seeded00OCT17Seeded0 NOV 30Seeded \J)CiJ

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TABLE21.Resultsoffieldseedingsonthedrainedcypresssite.DATEOFSEEDLINGCOUNTSAUG12AUG28ocr15NOV29AUG12 DNl'E WHENSEEDEDISeeded280 8 0 c AUG28Seeded50ocr15Seeded0NOV29Seeded '"'"

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100Fie1dPlantingsTreeseedlingsurvivalfor eac,.consecutive plantingoneachstudyplotisillustratedinFigure27.I,leanheightgrowthasof Noverrber 30forthesurvivingtreesfromeachplantingisshowninFigure28.Inmanycasesthetreeshadseveralmonthsofgrowth--eitherpositiveornegative--beforedying.Gainsandlossesofindividualseedlingsthateventuallydiedwerenotincludedinthecalculationofmeanheightgrowth.Inotherwords,onlythosetreesthatsurviveduntil Noventler 30wereused.TheseedlingsfromtheMarchplantingonthelongleafpineflatwoodsitedidnotsurvivethefirstmonth.Thismortalitywasprobablytheresultoftransplantationshockduringatimewhenthesoil mois turecontentwasvery 10'4.T\40 seedlingssurvivedthe May plantingandasoflate Novewber exhibitedanaveragegrowthofminus4..5 crt. Thenegative grotNth signifiesthat t...,.e topsof most ofthetrees died back.AllfiveseedlingsfromtheJulyplantinghavesurvivedandtheyexhibitedagrowthofminus8.8em.Noneofthetreesfrom t!lis plantinghadpositivegrowth.Theseedlingsappearedtobedeficientinnutrients;theyproducedsmall,paleyellowish-greenleaves .. Severalofthetreeswerebadlydamagedbyinsects.Onthemixed-hardwoodcypressforestsiteoneseedlingfromthe Barch plantingsurvivedWltilJuly. 1'v.... ootherseedlingshavesurvivedfromtheJulyplanting.Their F.ea, height growth asoflate VIasminus 11em. From t,heP,ugustpla.""1ting,included five pressseedlingsin ac1cli tiontothe only O::1e individualofeachspecieshas survived. ThE: singleEela.leu::a seedlinghas gro,'.,on 21.5 em,Illhilethe cypressseedling had a gro:,..;-th ofminus28.0 em.

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Figure27.Seedlingsurvivaloneachstudyplotfromthefourplantingtrials.Eachbarrepresentsoneseedling.Thelengthofthebarindicatesthetimebeforetheseedlingwasobservedtohaddied.The openendedbarsindicatethattheseedlingswerestillaliveon December1.(LPF,longleafpineflatwood:MHC,mixedhardwood--cypress;BMHC,burnedmixedhardwood--cypress;DwCF,dwarfcypressforest; WP, wetprairie;MCF,maturecypressforest;M,mangrove;DC,drainedcypress).

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102A 11 JJAso LPYt:lZM::iC........:i!Ir.cJ?..:l""'l-i1''"uMCFM LPFI MllC I mrnc IOweFI WP IMCFI M ILPF MCF .j ......--,:[.1i 1 eucaCyp:-essCypressB:mcMHC DC

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:-c-::'" c: (J).., 0 t:JtqC")..... 0w o t:l t'1 C")'-:I-'rt::>;:r 00. gl'iu).--.---------uC0"::> '1 '"GO<:Nixed Hardwood--Cypress 11l1l o0 Cyp r-hI""hCl.>TjI-'CjQ"'1rDN0:> rtH:..:r.::Ii::r'::J"r,)ro('"0)ro';Uro::>"'IIIl-'Ul\-i.::rOJ::lro o (Dj-'.(11-'-:c::::t'f.Jl-"(T,.,"ro:r<:;Qc_I'i'" 0 ;:1(}iTU:J':rCf4(t;u0ti,llJ-hr<'1"'rD'1rD(')ttl'"1-rjn. {O t.....(JlnJ}-I.rlJul(\)rt::J(/) Ul n'onrt;-.r::r'n1--1.(t)n'It'::r'

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104Theseedlingsplantedontheburnedmixedhardwood--cypressforestsiteexhibitedthegreatestheightgrowthofanyoftheplotsplanted.Italsohadoneofthebestsurvivals.FromtheMayplanting,twoseedlingshavesurvived.Theiraverageheightgrowthwas71.8em.AllfiveseedlingsfromtheJulyplantinghavesurvived,withanaverageheightgrowthof54.5em,butonlyoneofthe Augustl'la.nted Melaleucaseedlingshassurvived,growing61.5eminthreemonths.FouroutoffiveofthecypressseedlingsarestillgrowingandtheiraveragegrowthasoflateNovemberwas8.5em.Theresultsobtainedsofaronthisplotareinsharpcontrasttothoseofthe adjacent plotdescribedabove.Obviously,theburningwithsubsequentreductionincompetitionandreleaseofnutrientshashadanoticeableeffectonbothseedgerminationandseedlinggrowth.AllfiveseedlingsplantedinMarchonthedwarfcypressforestsitedidnotsurvivethefirstmonth.However, tHO of thefive seedlingsplantedinMaysurvivedandgrewanaverageof12.5embetweenMayandlateNovember.FromtheJulyplantingonlyoneseedlingwaslost.Theremainingseedlingsaveraged37.6emofheight Noplantingswere inAugust.Mostofthesurviving Leedlings appearedhealthythroughoutthesummermonths,butinlate November allwereseverelyinsect dalTIaged.Nost oftheseedlingsonthissitedevelopedaballofadventitiousrootsatthewatersurface.NoneoftheseedlingsplantedinMarchonthewetprairiesitesurvivedthefirstDonth.Oneseedlinghassurvived from the Hay plantingandasof late hadgrown40 CD. AllfiveseedlingsfromtheJuly havesurvived.Theyhadanaverage heightgrm,th of44.5 en. This ',.i':::'S thesecondbest grow"th response

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105obtainedfromanyoftheplantingsonanyofthesites.In Novenber severalofthetreeswerebadlyinsect OneseedlingfromtheMarchplantingonthematurecypressforestsitesurvived'beyondSeptember1,butitcouldnolongerbelocatedonOctober17.OneseedlingfromtheMayplantingsurvivedforfivemonths.BoththeMarchandthe May plantingstookplacewhilethesoilwasmoist.Alloftheseedlingswereplanted inJulyandremainedcompletelysubmergeduntiltheydied.Twoofthesesubmergedseedlingsdevelopedthedimorphicallydistinctleavesexhibitedbythesubmergedseedlingsgrowninthegreenhouse.Noneoftheseedlingsonthissiteexhibitedanypositivegrowthaftertheyweresubmerged,andallweredeadbylateNovember.Inadditiontotheseedlingsplantedonthemature forestplot,12largeseedlingsaveraging125eminheightwereplantedinJulyinthecenteroftheopenpondjustoutsideofthe plot.Mostofthetreeswerecompletelysubmergedbutafewhadtheirtopsoutofthewater.InOctoberallofthetreeswerestillalive,butbyNovember30theyweredead.OnthemangrovesitenoseedlingssurvivedeithertheMarchorMayplanting.AllfiveseedlingsfromtheJulyplantingsurvivedthroughAugust,butasofOctober17onlytwoseedlingsremainedalive.OnNovember30oneseedlingwasleftandithad gro\
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Figure29.PlantedcypressandMelaleucaseedlingson the drainedcypressforestsite.106

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SURVIVAL OF NATURALLY REGENERATEDSEEDLINGSThetremendousamountofMelaleucareproductionobservableinmanyareasofLeeandCollierCountiesusuallyresultsfrommassiveseedreleasefollowingtheburningofsitesthatalreadysupportatleastwidelyscatteredmatureMelaleucatrees.ThequestionarisesastothesusceptibilityofthesesitestoMelaleucaestablishment.Inotherwords,dothesesitesregularlyanduniformlypresentconditionsfavorablefor oristhepropertimingofseedreleaseaccompaniedwithfireandpropermoistureconditionsonlyinfrequentlymet?ObjectivesThevastacreageofLeeandCollierCountiesthatburnedduringthedroughtof1974presentedanopportunitytoobserveMelaleucaseedling establishro.ent afterburning.Thissimpleexperimentwassetupto:(1)observenaturalseedlingsurvivalonestablishedMelaleucasites,and(2)tostudyseedling onthesamesitesfromseedsownlaterinthesea30n.ProcedureThreedifferentsiteswere lo::ated where wasalreadyes"tablishedand \vhich hadburned the drysea.son.Hassive seedrelease hadoccurredon each ofthe sitesandseedlingsliterally107

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108carpetedthe Thesitelocations \oie:re: #1,duewestof Honroe stationinCollierCountyinanopengladesurroundedbyscatteredpine,cypress,andclumpsof Helaleucai #2,southofHighway846northeastofNaplesinCollierCounty,inmixedcypressandpineandscatteredMelaleuca;and#3,twomilessouthofEsteroinLeeCountyalongU.S.41,nexttoanoldcypressdome nowdominatedbylargeMelaleucatrees.Oneachofthesites,four20emby20emplotswerearbitrarilychosensothatnaturallyestablishedseedlingswereuniformlydenseoneachoftheplots.Atthebeginningoftheexperiment,theseedlingsononeplotoneachsiteweremerelycountedandrecorded.Ontheotherthreeplotstheseedlingswerecountedandremoved.Immediately,oneoftheclearedplotswasseededwith0.25gramofMelaleucaseed.Thesecondclearedplotwasseededinthesamemannerafteronemonth,andanyresponseonthecontrol theinitiallyseededplotswasnotedatthattime.Thethirdclearedplotwasseededafterapproximatelytwomonths.Waterlevelanddissolvedoxygencontentmeasurementswerealsotaken.ResultsThedatesofinitial establishment andsuccessivetreatments,alongwithresultsandmeasurements,are sUIn.rn.ari,zed inTable 22. Onsite#1,nearMonroeStation,thecontrolplotsupported45seedlingsatthetimeof establishment. Thewaterlevelwasapproximately13.5emabovethesurfaceandsixoftheseseedlings l,",'ereeG1ergent, thetallestbeing16em.After appro;
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109TABLE22.Survivalofnaturallyregenerated nelaleuca seedlingsonburnedsitesandtheresultsofseedingsonthe sitescarriedoutlaterinthewet Site1 Honroe Station(wet pine,cypress)NumberofSeedlingsDissolvedTreatmentWaterDepth02ContentDateControl1 2 3(em)(ppm)July2545seeded13.54.95Aug.31450seeded13.01.76Oct.1740330seededsoilmoistNov.30372133soilmoistSite2Highway846(Pine--cypress)NumberofSeedlingsTreatmentDateControl1 2 3July2578seededAug.317412seededOct.15502145seededNov.30500 1 0WaterDepth(ern)1.00.2soilmoistsoilmoistDissolved02Content(ppm)site3Estero(cypressdome)NumberofSeedlingsDissolvedTreatmentI-laterDepth02ContentDateControl1 2 3(ern)(porn)July2790seeded12Aug.31900 seec.ed 106.19 Nov. 28630 4 seededsoildry

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110plotsupportedthreeseedlings.Thesecondseededplotsupportedthirtyseedlings.Athirdplotwasseeded at thistime.Afterfourmonths37seedlingsremainedonthecontrolplot.Thefirst,second,andthirdseededplotscontained 2,13, and3seedlingsrespectively.Onsite #2, nearHighway846,thecontrolplotsupported78seedlingsatthetimeofestablishment.Therewere2 emofstandingwateratthetimeandalloftheseedlingswereunderwater.Amonthlater74seedlingsremainedonthecontrolplot.Therewasonly0.2cmofstandingwaterandalloftheseedlingswereemergent.Fromtheseedssownonthefirstseedingplot,12hadgerminated.ByOctober 15, thesoilwasmoistand50seedlingsremainedonthecontrolplot;21onthefirstseedingplot;and45onthesecondplot.Athirdseedingplotwasestablished.atthistime.BylateNovembertherewerestill50seedlingsonthecontrolplot,butonlyoneseedlingremainedonanyoftheseeded Onthethirdstudysite,nearEstero,90seedlingsweregrowingunder12emofwateronthecontrolplot. latertherewerestill90seedlingsonthecontrolplot,allstillgrowingunder10emofwater.Nogerminationhadoccurredontheinitialseeding plot. BylateNovembertherewere63seedlings renaining onthecontrolplot,whiletheonlyseedlingsestablished seedingsoccurredontheplotseededinlateAugus"t,which contained fourseedlings.

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DISCUSSION.SeedGerminationandSeedlingSurvivalSeveralmajorfactorscontrolMelaleucaseedgerminationandseedlingsurvival.Thesefactorsincludemoistureavailability,waterlevel,hydroperiod,soilfertility,salinity,light,andcompetitionwithnaturalvegetation.Inotherwords,acertainsetofbiologicalandphysicalinfluencesinteracttodefinetheconditionsnecessaryforMelaleucagerminationandgrowth.OnlyinthoseareaswheretheseconditionsarefoundwillMelaleucabecomesuccessfullyestablished.MoistureRequirementsThegerminationexperimentscarried out inthelaboratorydemonstratedtha"tunderidealconditions Nelaleuca seedgermination was initiatedrapidly,withinthreedays,andthatthegerminatingseedswereverysusceptibletodessicationifmoistureconditionswerenotsatisfactory.Thefactthatnogerminationoccurredfromseedsownonthestudyplotsduring the dryseasonsuggeststhataseedcropreleasedandonthegroundmay be extremelyvulnerabletotheseasonalvagariesofmostureavailability. betriggeredbyabriefdryseasonrain,or byor fog;butmoisturelevelswouldnotbesufficientfor growthandsurvival.Rapidgermination afterinitialmoisture application \.;ould be an toseed atthe ofthewetseason.III

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112Abundantmoisturewould be availableaspracticallydailyrainstormsdevelopandgerminationwouldprobablyoccurbeforeflooding.ThiswouldtendtofollowthesequenceofeventsthatoccursinthemonsoonclimatewhereMelaleucaisnative.Seasonaldroughtsprovideconditionsforfire,whichinturnresultsinseedrelease sitepreparationjustpriortotheonsetofthemonsoonrains.MuchthesamepatternexistsinSouthFlorida,especiallyasartificialdrainagehasshortenedthelengthofthefloodperiodandincreasedtheincidenceoffire.Althoughboththelaboratoryand experimentsindicatedthatMelaleucaseedswillgerminate und2rwater, thisdoesnotseemtobethecaseundernormalfieldconditions.Nogerminationwasrecordedonanyofthesiteswhilestandingwaterwaspresent.ThisindicatesthatareaswhicharecontinuallyfloodedduringthewetseasondonotnormallypresentconditionsfavorableforMelaleucaseedgermination.Thelowdissolvedoxygencontentcharacteristicofmostswampwatersmayeffectivelyinhibitoratleastdelaygermination.Wnetherornotseedisdestroyedunderprolongedfloodingisuncertain,butontheburnedstudyplotsomegerminationdidoccur,afterthedropinwaterlevel,onsubplotsthatwereseededasearlyasJuly_Whereseedlingswereobserved undenvater, germinationprobablyoccurredpriortoflooding,asforexample fro:n the seedingontheburnedplot.InNovember,seedlingswerealso observed thatweregrowing undenvater onthe dwarf cypress forest site.However,thissiteprobably \\las not flooded foratleas"t a.b:-:-ief period bet .;een the

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113OctoberandNovembervisits,and germinationmost likelytookplaceduringthisperiod.Thisissuggestedbyboththeobservationthatnewlygerminatedcypressseedlingsweregrowing underwater onthesite(cypressdoesnotgerminateunderwater),andthefactthatthesitewasvisitedjustafteracoldfronthaddroppedover2.5emofrainovermuchofSouthFlorida.Exceptonthewetprairiesite,thedissolvedoxygenlevelsinthewaterateachofthefloodedstudysiteswererelativelylow.BecauseMelaleucaseedsareminutethereisapossibilitythattheywouldlayentirelywithinalayerofanaerobicwaterthatmayexistatthesoilsurfacewherelittlewatermovementandmixingwouldoccur.Thismayaccountforthelackofgerminationonfloodedsites.Insomepreliminaryexperiments,itwasfoundthatMelaleucaseedswouldgerminateinsixdaysinwaterwithadissolvedoxygencontentof4.0ppm,whilenoseedgerminationoccurredaftertwoweeksinwaterwith2.5ppmofdissolvedoxygen.Apparentlygerminationandsuccessfulestablishmentwillnotoccuronsiteswhiletheyarecontinuallyfloodedduringthewetseasonnoronsiteswheretheseedhaslaidonthegroundthroughmostofthedryseason.Afavorablewindowforsuccessfulgerminationexistsonlyforbriefperiodsconfinedtoeithertheonsetofthewetseasonorafterwaterlevelsrecedeinthefall.Prolongedconditionsfavorableforgerminationwould betherefore, onlyonthosesiteswherethesoil surface is exposed butremainswetforlongperiodsof time.

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114Hydroperiodand LevelInthevaried-hydroperiodexperimentsundertakeninthegreenhousetheseedlingsinthetreatmentthatwasalternatedbetweensubmergenceanddrainageeverythreedaysseemedlessaffectedbysubmergencethanthoseinthetreatmentthatwasalternatedonatwoweekbasis.Theseedlingsofthefirsttreatmentbrokethewatersurfacemorethanamonthbeforethoseofthetreatmentthatwasalternatedeveryotherweek.Thissuggeststhat,eventhoughthetotalnumberofdaysofsubmergencewasthe same forbothtreatments,afluctuatingwaterlevelor"noisy"hydroperiodismorefavorableforMelaleucathanastablehydroperiod.ThesefluctuatingwaterlevelsarecharacteristicofthoseareasinSouthFloridathathavebeenartificiallydrained,andincludethoseareas where Melaleucahasbeenactivelyinvading.Forexample,maximumrecessionratesofgroundwaterlevelswithintheFahkaUnion--GoldenGatedrainagesysteminCollierCountyarebetween9.1and10.4ernperday,whilemaximumratesforundrainedareasoftheBigCypressSwamparebetween2.1and4.0ernperday(Carteret. al., 1973).Drainagecanalsinsomeareashavealsoincreasedtherateofsurfaceflowoneorderofmagnitudeovertheaverageof0.5kIDperdayintheBigCypress Swamp (Carteret.al.,1973),effectivelyremovingsurfacewateratarapidrateandcausingdramaticfluctua-tionsinwaterlevelsandlengthofhydroperiod.Thefactthat r-!elaleucagro'.. ;thceasesoratleastis significan-tly slowedwhenplantsare submergedwas deoonstratedinboththegreenhouse experiRents andinthefieldon th9 burnedmixedhardwood--cypresssiteandmaturecypressforestsite r \;here both the gCl:.Ii1.inated and some

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Usplantedseedlingsrenainedsubmergedthroughoutthewetseason.Apparently,seedlingsthatdogerminate underdater farmmorphologicallydistinctleaves.Thegreenhouseexperimentsalsoshowedthatseedlingsestablishedunderdrained,conditionsloosetheirnormalleavesuponsubmergence,developthetightclustersofmorphologicallydistinctleaves,andceasefurthergrowth.Floodingseemstohavelittlenoticeableeffectonseedlinggrowthoncetheapexoftheshootbreaksthewatersurface.Anuninterruptedhydroperiodwitharelativelyconstantwaterlevelwouldtendto seedlinggrowthbykeepingtheseedlingssubmerged throughout thewetseason.Afluctuatingwaterlevelandsporadicfloodingduringthewetseasonwouldpermitgreatergrowthandimproveaseedling'schancesofsurvivingthedryseason.Onthewetprairiesitetheplantedseedlingshavebeen(orwillbe)subjectedtoaneighttonine month inundation.Evenso,bothheightgrowthandsurvivalhave been good.Thissuccessmaybetheresultoftwofactors.First,thereis absenceofanyovertoppingvegetation,andsecond,increasedstemelongationmayhaveoccurredinresponsetothefloodedconditionstofacilitategasexchangethroughagreaternumberoflargerintercellularspaces.Also,noneoftheseplantshaveproducedanyadventitiousroots,indicatingthatthehighdissolvedoxygenlevelsrecordedaresufficienttomaintaintheseedlingswithouttheir energytoproduceadventitious roots. Ontheotherhand,it see3S thatthis t)rpe ofsite \'louldrarelypresent conditions favoriJ.blefo;:" ::elaleucageminationbecause hydroperiodismaintained(in t:lis caseartificially)foralong p'2riod oftime. The period \'lhenagCrP.1inatedseedling could grot"suf ficientlyto overcome theeffectsofthe prolo:1gedhydroperiod would

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116 beafterburning,whichwouldreleasenutrientsanddestroythealgalmat.Still,theseedlingwouldhavetopasseighttoninemonthsunder water incompetitionwithanewlyformingalgallayer.Theseconditionswouldbesimilartothecompletelysubmergedtreatmentinthegreenhousehydroperiodexperimentwhere,overaperiodofayear,athickalgal mat developedoverbaresoilandcompletelycoveredtheMelaleucaseedlings.Wherehydroperiodshavebeenartificiallyextended,itseemsunlikelythatMelaleucawouldeverbecomeaproblem.Forexample,partsofConservationArea3Ahavebeencontinuouslyfloodedforthepasttenyears.Infact,waterlevelshavebeenmaintainedsohighthatfloodinghascauseddamagetomostofthetreeislandsinthelowerthirdofConservationArea3A.Thisisreadilyapparentasone travels throughthisarea.Ontheotherhand,thecanalsystemthatdrainsthisareatendstodryoutthenorthernendoftheConservationArea.ItisinthenorthernthirdwherescatteredMe1aleucatreesarefound.BiologistsoftheCentralandSouthernFloridaFloodControlDistricthavenotedthatMelaleucarapidlyinvadedConservationArea28onlyaftertheconstructionofadrainagecanalloweredwaterlevels(Dineen,1972).FireFireundoubtedlyplaysanactiverolein thedistributionpatternsofHelaleucain S::JuthFlorida. Itis common tofind laleucaoccupying theshallo',':F:)rtions ofacypressdomeorstrand1 where \,ater levels b2en10l.j2red. Itcanbe conje8tured thatduringdryperiodssurface soils are drier inthehigher! better

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117drainedfringesofas"trandor d02.2 thanatitslowercenter,andfiredamageisincurredmorefrequentlyandseverelyatthesefringes.IntheabsenceofMelaleucatheseburnedsitesarereclaimedbycypress,or,ifaffectedbydrainage,bypine.When aMelaleucaseedsourceispresenttherapidgrowthofMelaleucacaneffectivelypreemptthesitefromcypress.Itshouldalsobepointedoutthatafterburning,whichnormallywouldoccurinthedryseason,Melaleucaseedwouldbereleasedonthesiteatleastsixmonthsbeforethecypressseed,whichisnotreleaseduntilthefall.TheeffectoffireintheecosystemsofSouthFloridaisinsep-arablylinkedtohydroperiod.Ashydroperiodsareshortened, latedplantmaterialandorganicsoilsaresubjectedtogreaterdegreesofdessicationforprolongedperiodsof time andthechancefor destructivefiresisincreased.Thecompleteremovalofannualfloodingonthedrainedcypressstudyplothasresultedinabuildupofaflammablegroundcover(Fig.30).Mostofthecypress wouldprobablybekilledifthissiteburned,whilethenutrientsreleasedwouldbeavailabletoplantscolonizingtheburnedsite.IfthesenutrientshadbeenavailabletotheMelaleucaseedlingsestablishedonthesite,perhapstheywouldhavestimulatedenoughgrowthduringthebriefperiodwhenmoistureconditionsweresatisfactorytosurvivethedryseason.Theinfluenceoffirecoupledwith th9 effectsofflooding tohave allowedNelaleuca to beC0r.12 established on theburnedmixedhard\>Tood--cypress site, \vhile avery sinilar adjacentsit_ethathadnotbeenrecently burned didnot permi t nelaleuca establishmentand t ....S not favorable for l'!elaleucag:'O'.lth.prepai::-ationeitherby fire or

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118Figure30.Drainedcypressforeststudysiteshowingthedenseherbaceousgroundcoverwhichincreasesthefiredanger. ,

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119mechanicaldisturbance whichrenoveslitter competingvegetationisprobablyaprerequisitefor ''elaleuca invasion.AlitterlayerontheforestfloormayactasaphysicalbarriertoMelaleucaseeds.Seedssownonalayeroflitter,ifcaughtwithinthelitter,wouldnotencountersufficientmoistureforgermination.Evenseedsthatfallorarewashedthroughthelittertomineralsoilwouldprobablynotbeable growthroughthelitterlayerduetotheminutenessoftheseedlingsandthesmall offoodreserveswithintheseed.Fireeffectivelyeliminatesthisbarrier.Evenifaseedlingdoesmanagetogetthroughthelitter,itwouldstillbeovertoppedbytheextantvegetation.Thisovertoppingandshadingmayhavebeenthecauseofboththepoorsurvivalandpoorgrowthobtainedonthe mixedhardwood--cypresssite.Meskimen(1962)pointedoutthat Nelaleuca tendstoformeven-aged starlds, whichsuggeststhatMelaleucaisashadeintolerantspecies.IntestingtheeffectsofshadingonHelaleuca,;:eskimen(1962)foundthatacomparisonofseedlingdiamaterandshootgrowthoffield-grownsunandshadeseedlingsrevealedlittledifferencebetweenthetwo.Usingcontrolledshadingregimesrangingfromfullsunlightthrough36percentshade,64percentshade,and90percentshade,heightgrowthdifferenceswerealsoroundtobeinsignificant;however,generalob-servationssuggestedthatstemsofshade grm'ln seedlings Here weakerthansun gro'tmseedlings. Dry h'2ightrneasurerr:e:nts oftherootsandshootssupportedthehypothesisthat moredry'-las beingproduced in thestemsofthe shade::1 individuals attheexpense ofroot production.Althou9'hl-lelaleuccl could probably be shade intolercmt,

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120asaremostsuccessionaltreespecies,it seems quitepossiblethatMelaleucacouldmaintain a,d perpetuateitselfona site_ FewshadetolerantspeciesareobservedgrowingwithinMelaleucaforests,possiblyduetorepeatedfiressweepingthroughthesestands.Thesefireswouldhelpmaintainlowamountsoflitter,wouldreleaseseedandnutrients,andeliminateanyunderstoryvegetation.AnycanopyopeningscouldprobablyberapidlyfilledbynewlygerminatedMelaleucaseedlings.IndensestandsthereisprobablyaconstantrainofMelaleucaseedsreleasedbynaturalpruning.ItisalmostimpossibletolocateMelaleucastandsthatdonotshowevidenceofrecent burning_ Fire frequency may,infact,beincreasedwithinstandsduetotheMelaleucatreesactuallydryingoutthesoilsurfacesoonerthannormallywouldoccur.MelaleucaandotherMyrtaceoustreegenera,suchasEucalyptus,havereputedlybeenutilizedtodryoutwetareas. .fuether thetranspirationrateofMelaleucaisactuallygreaterthancypressisnotknown,butinthecaseofMelaleucaitwouldbeayearroundprocess,whilecypress,whichlosesitsleaves,mighttendtoconservemoistureduringthewintermonths.Duetotheirlocationintopographicdepressionsandbecausetheyactasreservoirsofmoisture,cypressstrandsanddomesprobablyactaseffectivefire Veryseldomwouldconditionsexistforanentireundrainedcypress toburnto theextent thatthevege-tationwouldbesignificantlyaltered. Thiswould tendtolimit Nela19uca tothe fringes, which are more susceptible tofire damage. Melaleuca,withitsfire triggered seedreleasemechanism, thick insulatingbark, a:1dspro'..ltinfjability 1is o'!J-;.. -iouslyafireadopted

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121 Infact, Nelaleuca maydependonfireforitscompetitiveadvantageoverotherspecies.PerhapswithouttheweakeningeffectofseverefiresonthenativevegetationtheextentofMelaleucainSouthFloridawouldbesignificantlyless.NotonlymustthefirereleaseMelaleucaseedandproduceafavorableseedbedbutalsoitmusteliminatemuchofthecompetingvegetation.Forexample,attheburnedmixedhardwood--cypress site thefireandsubsequentfloodinghadseveralmarkedaffectswhichresultedinthesuccessfulgerminationandrapidheightgrowthofMelaleuca.First,thefireeffectivelyremovedthegroundcoverandcompetingvegetation.Second,nutrientsreleasedfromtheburnedvegetationandlitterwereavailableforbothgerminatingseedlings fu,d plantedseedlings.Third,firedamagetoovertoppingtreesandshrubsopenedthecanopy,resultinginagreaterinputofsolarenergy.Finally,floodingeffectivelycheckedtheencroachmentorreinvasionofmanyotherherbaceousplantssothatinthefall,afterthesoilwasagainexposed,muchofthesitewasstillunoccupiedbycompetingvegetation.Itremainstobeseenifthemanyseedlingsnowestablishedfromseed can survivethedryseason.Theuninterruptedfivetosixmonthlongfloodperiod,whichcurtailedgrowthofsubmergedseedlingsandpostponedfurther gemi nationuntillatefall,maystillprovetobethefactorthatpreventsMelaleucafromtakingoverthesite.Iti.simpossibletofind Hela.leuca gro'."ingonsites y:here somesortof disturban,:e has noto,::curred. Changesin thehydroperiodand destructionof exis-tingvt2get2tionSe2El. tobeprerequisites forany sortof Melaleucainvasion. Itseemsunlikelythatcypress \,:ouldbe abletoreproduce andsuccessfuJly\,itht-!21aleucaon drained

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122sites,evenifthecypressarenotkilledbyfire.Thealterationofthehydroperiodwouldmakeitextremelydifficultforcypresstocompletegermination.Thecypressseed,whichisnormallyreleasedinthefall,wouldencounteradrysoilsurfaceoronethatisonlyinfrequentlymoist.Langdon(1955)notedthatthemainrequirementforcypressseedgerminationisabundantmoistureforaperiodofonetothreemonths.Theseedswillnotgerminateifsubmerged,butwillremainviableunderwater.Normally;cypressseedwouldeitherfallonwetsoilorintorecedingfloodwatersandgerminateassoonassaturatedconditionswerealleviated.SiteSusceptibilitytoMelaleucaInvasionFieldobservationstendtosupportthehypothesisthatthetypesofsitesmostsuitableforMelaleucainvasionarethoseareaswithperiodicshallowsurfacefloodingduringthewetseason.Here,evenminorwaterlevelfluctuationsperiodicallyexposethehigherareas,butthesurfaceseldomifeverdriesoutorissubjectedtoextendedfloodingduringthewetseason (rigs. 31and32).Thevegetationmostcommonlyfoundunder these conditionsiseitheramosaicofcypressandpinestandsormixedstandscomposedofthesetwospecies.ThesemixedstandsandmosaicsarecommonlyfoundontheacidsandsofwesternLeeandCollierCountiesandextendintotheBigCypressregion. Much ofthedrained area oftheFahkaUnion--GoldenGatecanalcomplexsupportsthis ofvegetation.Someofthe pin9 sitesandexcessivelydrainedcypress standsnayno,."be toodryforsuccessfulI-1elaleuca establisrlJ."'{lent,butDuch ofthisareaisprobablyvery

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123Figure31.Me1a1eucaseedlingsonanidealsiteforsuccessfulestablishment.Thesesitesfrequentlysupportasmanyas2000seedlingsperm 2

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124Figure32.DenseMelaleucareproductioninadrained(butperiodicallyflooded)andburnedcypressforest.

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125susceptibletoMelaleucainvasionas moisture conditionsareidealandfiresarenowmorefrequent.ObservationsmadeatthetransitionzonebetweenMelaleuca andnativevegetationseemtoindicatethatMelaleucaoccupiesthewetpinelandsitesandthosecypresssiteswhicharemostfrequentlydrainedandburned.Inotherwords,Melaleucamaybeinvadingthosepartsofthehabitatsofbothpineandcypressthatarenotparticularlyfavorableforeither.Thesamethingcanbesaidofthetransitionzonebetweencypressandwetprairie,andpineandwetprairie.Melaleucaisfoundtooccupythehigher,morefrequentlyexposedsitesinthewetprairies.ItwouldbeextremelyunlikelytofindMelaleucagrowinginasloughthatiswetmostoftheyear.AreconnaissanceofConservationArea3AinDadeCountybyairboatduringthewetseasonshowedthatonlyinafewplaceshad becomeestablished.Itcanbeconjecturedthatthesefewstands establishedduringaseveredroughtfollowedbyfire,orwhenwatermanipulation.producedunusuallylowwaterlevels,andthattheirfuturespreadisessentiallyheldinabeyanceuntiltheseconditionsagainpresentthemselves.WaterlevelatthetimeofobservationwasoverameterdeepandtheonelargestandofMelaleucathatwas appearedtobebreaking up. Manyofthetreesinthecenterof the standhadfallen,producingan impen etrablemassofdeadordown trees (Fig.33).Thestandingtreesexhibitedmassive or roots; sow8 oftheroots \.;erewoody and sev2ralcentimetc:.t"s in dia.rnetel, suggestingthat Hater levelshadbeenhighfor SO!7l2 (Fig.34).These trees couldeasilybepulledoutofthegroundby even though some wereover15em

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Figure33.AMelaleucastandinConservationArea3A.(a)Viewofdome like appearanceofstand.(b)Interiorofstandshowingfallen,dyingtrees.Thisstandappearstobedyingbecauseofcontinuouslyhighwater.

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(a)127(b)

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128Figure34.Large,woodyadventitiousroottypicalofthosecommonlyfoundonMelaleucagrowingoncontinuouslyfloodedsites.

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129indiameter,indicatingthattheyhadeitherfailedtoproduceadequateroot orthattheirrootsystemshaddiedduetothecontinuouslyfloodedconditions.Sitesthatareunfloodedthroughouttheyearmayonlypresentconditionsfavorableforgerminationforbriefperiodsduringthewetseason,andwouldrarelyexhibitsatisfactorymoistureconditionsrequiredforgrowthandsurvival.ThelongleafpineflatwoodstudysiteisanexampleofanareathatisnormallytoodryforMelaleuca.Slashpineflatwoods(Pinuselliotii)areprobablymorefavorableforMelaleucaestablishmentbecausetheytendtooccupysoilsthatarenotonlysubjecttooccasionalsurfacefloodingbutalsoremainwetforlongerperiodsoftime.ManyoftheartificiallydrainedcypressandslashpineforestsinCollierCountyareprobablynowverysimilartothedrierlongleafpinesites.AconsiderableportionofwesternCollierand Lee Countiesconsistsofthesedrylongleafpineflatwoods,andverylittle leucainvasionhasoccurred.ThoseMelaleucatreesthatarefoundtoexistaseitherisolatedindividualsorstandsthatareusuallyrestrictedtodefinitedepressionswheremoistureandpossiblynutrientscollect.Thelongleafpinesitewasnotonlyunfavorablefor Helaleuca seedgermination(almostnoneoccurred)Ibutseedling growth wasverypoorthereaswell.Seedlingsurvivalwashigh,buttheseedlingsappearedtobe nutrient-deficient,unhealthy,and Ontheotherhand, Nelaleuca seedling gro'.vthor. thedrainedcypresssite \'las con-siderablybetter. Tnis probablyindicatesthatthere significantsoildifferences bett-leenth232t,;o drysites and if woisturecor:di lions

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130occasionallybecomesatisfactoryonthedrainedcypresssite,itwouldbemuchmoresusceptibleto Nel2.1euca Thematurecypressforestobviouslydoesnotnormallypresentconditionsfavorableforsuccessfulgerminationorsubsequentgrowthof Eventhoughmanyoftheplantedseedlingssurvivedagoodpartofthewetseasonunderwater,thehydroperiodonthissiteisrelativelylongandasthewaterleveldropsinthefall,flowthroughthesitepracticallyceases;thewaterthenbecomesstagnantandoxygendepleted.Thedenseshadeovermuchoftheplotwouldprobablyalsobeafactorlimitinggrowthofanyemergentseedlings.AlthoughMelaleucaseedlingshavebecomeestablishedduringthelatefallonthedwarfcypressforestsite,itseemsunlikelythattheywillsurvivethedryseason.SeedlingsestablishedfromseedasearlyasNovemberthepreviousyearwerealldeadbyMarch.PerhapsfirethatwouldremovethethickalgalmatandreleasenutrientswouldbesufficienttoopenthissitetoMelaleuca.Eventhoughtheplantedseedlingshavebeenheavilyinsect-damaged,growthhasbeengood.Thegenerallackofanygerminationandthesurvivalofonlyoneplantedseedlingonthemangrovesitesuggeststhat,atleastinthisparticularcase,salinitymaybeanimportantfactorlimitingtheencroachmentofMelaleucaintomangrove-dominatedareas.Thesurvivalthatdidoccurresultedfromamid-wet-seasonplantingwhentherewasasignificant.fresh Hater input; ho"..... ever,theentiresite VIas floodedatthistimeso favorable conditionsfor germination didnotexist.Thesinglesurvivingseedling has produced Ithickerthan normal leaves in responseto",,'hatis slightly brackish..... ater Thepossibility thatmightinv.::demangrove sites Has suggested

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131bytheareasthatitinhabitsinSou'theastAsia.AlthoughnosignificantMelaleucainvasionofmangroveareashasyetbeennotedanywhereinFlorida,mangrovesitesdovaryconsiderablyastosalinity,soils,andspecies.DuetothisvariabilitythestudysitemaynothavebeenrepresentativeofmuchofthemangroveareasinSouthFlorida.Perhapsseedingandplantingtrialsshouldbetestedonabuttonwoodsite(Conocarpuserectus)becausethisspeciesoccupiesthe"backmangrove"inSouthFlorida.QualitativeMelaleucaModelThebasicfactorsaffectingtheabilityofMelaleucatoinvadeanecosystemaresummarizedintheenergyflowdiagraminFigure35.WaterlevelisconsideredtobetheprinciplefactorcontrollingthetypeofvegetationthatasitewillsupportandthevulnerabilityofasitetoMela1eucainvasion.Ifwaterlevelsarehighthenativevegetationtypes,utilizingthenutrientresourcereleasedthroughdecomposition,willcontinuetogrowandperpetuatethemselves.However,whenwaterlevelsareloweredbyartificialdrainageandlitterlevelsarehighseverefiresoccurwhichconsumethelitteranddestroymuchofthevegetation.If 1-1ela leucaisalreadyonthesite,seedwillbereleased.If moisture levelsthenfallwithintherangedescribedas favorable for Me121euca establishmenttheseseedswillsuccessfully Even though drainage has occurredandfires are frequentthe Qoisture levelsrequi redfor !J1elaleucaI\lclY not b'2p:cesenta!1:1the seedcrop o;./ill belost.If N?laleucadoesi:. isstilldependent OLl the

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'. / J.,-: ,/' .,..-' 35.Qualitativeenergyflowdiagramof caopetition.., .j.i

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134waterlevelforitscontinued ability toutilizethe resources. Ifwaterlevelsagainrise,conditions may forconti-nuedgrowthandthetreeswilldieout.(Thesewaterconditionsareindependentoftheconditionsrequiredforgermination.)IfMelaleucaisnotpresentonasiteatthetimeofburninganyinfluxofMelaleucaisdependentontheoutsideseedsourceandfavorablemoistureconditions.ThecruxoftheMelaleucaprobleminSouthFloridaseemstoberelatedtothepresenceorabsenceofthesefavorablemoisturerequirementsforgerminationandthedegreetowhichsitesaresubjecttofloodingandburning.BecausethisfieldstudyhasnotyetbeencarriedthroughthecompletecycleofwetanddryseasonsitisdifficulttodrawanyfinalconclusionaboutfavorablesitesforMelaleucaestablishmentand what combinationofsiteconditionsare-required.However,certaintrendsareevidentandtentativeconclusionscanbemade.(1)Itseemsunlikelythatseedgerminatedduringthewintermonthsonanyofthesitesdescribedwillsurvive,whileseedsreleasedduringthedryseasonmaynotremainviableforextendedperiods.(2) Survival andgrowthseemtobebetteronopen,disturbedsitesthanonundisturbedanddensely v2getated sites.(3)Seedsapparentlydonotnormallygerminateunderwaterunderfieldconditions,thus, 2reasth2t floodedquicklyafter the initialrainsbeginmay not beconducivetogermination;the higher,morcirregularly floodedsitesareprobably morefavor2.ble.

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135(4)Soilfertilitymayaffectthe abilityof seedlingstogrowrapidlyenoughtosurvivedryperiods;in na,y casesthenutrientsreleasedfromburningmaybeasufficientimpulsetostimulatetherequiredgrowth.(5)Newlygerminatedseedlingsappeartobe able towithstandsubmergenceforextendedperiods,whilelargerseedlingsappeartoberelativelyunaffectedbywaterloggedsoils,butwilldevelopdimorphicallydistinctleavesandforallpracticalpurposesceasegrowthif submer-ged. Thisstudy,atitspresentdevelopment, ta,tatively supportstheconclusionthatconditionsforMelaleuca evenondisturbedsites,arepresentforonlyalimited oftimeeachyearandthattheseconditionsarecriticaland bemet.Certainsiteconditionswhichmayhavebeenincreasedin area by hunan activitieshaveresultedinanincreaseintheareaoccupiedbysiteswhicharesusceptibletoinvasion.Dueto Lhese alterationsintheenvironment,theeffectiverange,ofMelaleucahasbeenextendedand probablyin cludesmuchofthedrainedareasofwesternandcentralCollierCounty,especiallythosesitesthatsupportcypress whileundisturbedareasofnativevegetationwillprobablyberelativelyfreeof Melaleuca.Management Directcontrolof Melaleuca is c.ifficult.. Theuseoffirereleases seedand normally doe.snotkilltree3. Cutting rer:lOval doesnothingbut sp!:"outir:;,2....'l.c1::elale'.J.ca isapro-lificsproutcr (Fig.36). It sproutsfro:1.th"O::::-:3.inster:land branches the tophasbeenkilled byfrost,fire,:elling. Thesprouts

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Figure36.BurnedstandofMelaleuca.(a)Immediatelyafterthefire,(b)threemonthslater.

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(a)(b)137

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138usuallyoccurjust belowthe pointofdamage.Saplingslessthanacentimeterindiametersproutatgroundlevel(Meskimen, 1962). Rootsproutsorsuckershavenotbeenobservedbyme,butnurserymenusecuttingsofimmaturewoodorbitsofslenderrootslaidhorizontallyonthesoiltopropagateMelaleuca(Morton,1966).Duetoitsrapidgrowth,longsucculentgrowingregionsaremaintainedthroughouttheyear,buttheseareinvariablykilledbackduringfrostperiods.Themultiple-stemmedindividualsareprobablyproducedwhenseedlingsarekilledbacktogroundlevelandsubsequentlysprout.Thesemultiple-stemmedtreesarefrequentlyobservedinthemorenortherlyextentoftherangeofMelaleuca,wherefrostismorefrequent.Meskimen(1962)pointedoutthatin1958,agroupof30to45emtallseedlingswasplantedintheAustinCaryForestinAlachuaCounty.InJanuary1959theywereallkilledbacktogroundlevelbysubfreezingtemperatures,butbyMarcheachstemhadproducedsprouts,andwithineightweeksthesesproutsexceededtheheightoftheoriginalseedlings.Stumpsproutsonlargetreesdeveloprapidlyafterfelling,growingthroughseveralinchesofbark. Ifnen treesareincompletelysevered,bulldozed,orwindthrown,sproutsdevelopalongthedorsalsurfaceofthestem,producingseveralnewsternswhereonlyonehadexistedbefore(Meskimen,1962).Thesesproutingcharacteristicsprecludemostconventionalmeansofcontrol.Completecuttingproduces stprnp sproutsandreleases seed, whilebulldozingorincompletefellingproducesagreaternumberof new vigorous stems. Burningreleasesseed,inducessprouting,andreduces comp8tition. Thesuccessofherbicideshas b8en limited.Itisnot to find Melaleuca

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139standsgreatlyincreasedinsizebyan attempttocontrolthembycuttingorburning(Fig.37).Atthislatedatetheprobabilityof cO:1trolling /1elaleucaoverextensiveareasislimited.Itsoutrightelimination,exceptonasmallscale,seemsnearlyimpossible.Mela1eucawillhavetobeacceptedaspartofthelandscape.BeyondthisacceptancetherearepossibilitiesforlandandwatermanagementprogramsthatmayhinderitsspreadandprovideforitsexclusionfromsuchareasasEvergladesNationalPark,theConservationAreas,andtheundrainedregionsoftheBigCypressSwamp.Theseareas,relativelyfreefromMelaleucaatthepresenttime,couldcontinuetobemaintainedinsomesemblanceoftheiroriginalvegetation.Fromthedatacollectedthusfar,severalmanagementpossibilitiesareapparent.Thefeasibilityofthesuggestionsofferedhere,alongwithanyothermanagementschemesthatmaydevelop,shouldbetestedonasmallscalebeforetheirwidespreadapplicationisconsidered.ItmustberememberedthatduetoSouthFlorida'suniqueenvironment,theeffectsofanylocalmanipulationofwaterlevels,hydroperiods,fire,andtheuseofherbicides-, etc. canhavefarreachingeffectsinboththenaturaland aspectsoftheecosystem.WithinthenaturalpreservesofSouthFloridaitappearslikelythatanintegrated ofbothwater firemanagement,coupledwith vigilance andthe an ecosystemisrelatively resistailt tc invasio:1tca.:--,exclud2 fromthese areas. Inotherwords, thosef2.c:ors\,.. hich siveNelaleuca acompetitive advantageovera particulct!'.:' na'tive vegetation typecouldbecontrolled.This does notmeanl aretur.ntofire

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Figure37.Melaleucastumpsproutssixmonthsafteracontrolcutting,KoreshanStateRecreationArea,July1974.140

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141butratllertheselectiveuseoffireinthoseareaswhichregularlypresentfavorableconditionsfor t!elaleuca establishmentandareclosetoaseedsource.TherapidinvasionofaburnedsitewillnotnormallyoccurunlesstherearealreadyMelaleucatreesonthatsitetoprovideaninputofseed.LargeareasoftheEvergladesNationalParkcouldburnseverelywithouteverincurringanythingapproachingaMelaleucareplacementofthenativevegetation,evenifsiteconditionsarefavorable.Aseedsourcedoesnotexistwithintheparkatthistime.Allthatcouldoccuris the establishmentofafewindividualsfromerrantseed.Thesecouldbeeliminatedeitherbyuprootingandremovingorbyusingacombinationofcuttinganddirectapplicationofherbicide.Onlyifthisinitial isignoredwouldthepossibilityofuncontrollableinvasionexist,assumingtheotherconditions,includingsitedisturbanceandappropriatesoilandwaterconditionsexist.InsusceptibleareassupportingwidelyscatteredMelaleuca,whensoilconditionsaresuchthatanearlyseedfallwouldnotencounterconditionsfavorableforsurvival,earlyseasonprescribedburningmightbeusedasaseedreleasemechanism.MuchofthedrainedcypressareainCollierCountywillburninthefall.Thiswouldputtheseedonthegroundatatimewhentheseedlingswouldbesubjectedto lli' satisfactorymoistureconditions.Also,frequentfallburningintheseareaswouldtendtofavorpine.Fuel reduction andsitepreparationatthetimeofpineseed release':'JouldenhaTlce pine establish..'nent andreducelossesfromsevereburning. 'Jn19ss attemptsaremadeto slotV' runoffthrough drainage canals, by special structuresorpossiblyby ingaqua.ticvesretation to slo'",' ..;,:;,.terflo',-] throughthecanals,the

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142cypressforestsinmuchof vlestern CollierCOWltycanprobablybewrittenofftopine,hardwoodsIor Helaleuca. Thedecision \'lould havetobemadewhethertofavorhardwoodsthroughfirecontrol,orpinebylatefallburning.NeglectwouldopenmuchofthisareatoMelaleuca.WatermanagementposesaprobleminthatmuchofSouthFloridahasalreadybeenaffectedbydrainage,andeveninareaswhereafairdegreeoffreedomdoesexist,severedroughtconditionsperiodicallyoccur.Anywatermanipulationprogrammustbedesignedtoalterthehydroperiodsothatthetimebetweenseverefiresislengthenedandthelossoforganicsoilsthroughburningandoxidationreduced.However,itisimportanttoemphasizethatthemanagementofwaterlevelsandhydroperiodcouldhavedrasticeffectsonthedesirableenvironmentalcharacteristicswhichecosystemmanagersaretryingtomaintaininSouthFlorida. forthesolepurposeofcheckingthespreadofMelaleucashouldnotbeconsideredasamanagementgoal.Thereexistsanothermanagementpossibilitythatcouldbe imple mentedonalimitedscale.ThiswouldinvolvetheuseofexistingMelaleucastands,especiallythosearoundtheNaplesandFortMyersareas,asreceptorsofsecondarytreatedsewage(Fig.38).Thefeasibilityofusingwetlands,especiallycypressdomes,as seHage receptorsandnutrientfiltersispresentlybeingtestedattheUniversityofFlorida.Mostwetlandareashavebeenrecognizedasefficientnutrientfiltersandwater Thepossibilityexistsnotonlyfortheuseof HelaleucaS'tJilillPS forthispurposebutalsoforusing sewageeffluent asaneventualmeansof eliminating::elaleucaover limited areas.Se'idageefflueEt could be.p:..:. .. ::,ped intosomeofthelargeformer cypressstrandsanddomes that arer:.O\-;dominated by 1,1e 1a1 euca. The

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i 143Figure38.MatureMe1a1eucaforestatSix-mileCypressStrand,southeastofFortMyers.ThisisthekindofMe1a1eucaforest which mightbeusefulforrecreationorsewagedisposal.

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144successionalnatureof Nelaleuca\
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145FutureSpreadinSouthFloridaand Environmental ImpactTheconsiderationofthespreadof l-1elaleuca assolelyabiogeographicalproblemhasbeenavoidedinthisstudy.IfeelthatalterationsintheecosystemsofSouthFloridahavebeenresponsiblefortherapidspreadofMelaleuca,ratherthanthemerepresenceorabsenceofaMelaleucaseedsource.ThoseareasinSouthFloridathatdonotatpresentsupportMelaleucaprobablydonotbecausetheirnaturalstatehasnotbeensufficientlyalteredtopresentconditionsconducivetoMelaleucaestablishment,oratleastthetimelagbetweendisturbanceandinvasionhasbeentooshorttorealizetheeffects.Theoccurrenceofprevailingwinds,waterflow,andothergeographicalconduitsandbarriersarenotlookeduponasbeingtheprincipalfactorscontrollingthepatternsof l1elaleuca establishmentthatexist.The.EvergladesNationalPark,ConservationArea3, theeasternportionoftheBigCypressSwampdonot support lar.ge of l1ela leucabecauseitcannotcompeteandcannotbecomeestablishedundertheconditionsthatarenormallypresentthere.Theisolatedstandsandindividualsthatareoccasionallyfoundareprobablynottheincipientprecursorsofadramaticchangetakingplace,butareremnantsofwhathadoncebeenafavorablesiteforashortperiodoftimewhenachanceseedingtookplace.Melaleucashouldbelookeduponasaweed,anaggressiveinvaderofunoccupied,disturbedsites,notasanactiveinvaderofundisturbed,natural ecosystems. Itseemsunlikelythatanyoftheareasnotpresentlybeingcolonizedby NelaleucahavenotatsometimereceivedaninputofMelaleuca Onlyafterasitehasbeendisturbed viill!;elaleuca besuccessful.Inotherwords, probablyoccupies,andwillcontinueto

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146occupy,thoseareasinSouthFloridathat s\.l,?port,,'eedy species; like\
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147ecosystemsbutalsoasmuseums ThisIIas the first \"hite mansawitllsyndromeisinconsistentwithbasicecologicalprinciplesandprobablyisinthelongrundetrimentaltothe Vegetationcannotbemanipulatedtoremaininastaticstateorreturntosomehistoricconditionwithouttremendousenergyinputstodivertorreversethenaturalenergyflowswithintheecosystem.MostnaturalpreservesinSouthFloridaaresotightlylinkedtothesurroundingecosystemsthatthosechangesoccurringoutsideoftheir boundariesgreatlyaffectwhathappensinside.Theseareasshouldbelookeduponasdynamicsystemschangingnotonlydueto manipulationbutalsothroughlongtermclimatic,geologic,andbiologicchanges.Theecosystemsshouldbemanagedtomaintainthediversitynecessaryforstability.Inotherwords,theyshould be managedforhealthy,nothistoric,

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LITERATURE CITEDAlexander,T..patternsReport.R.1973.RecentandinsouthernFlorida.113pp.longtermvegetationalchangesandSouthFloridaEnvironmentalStudyBailey,E.M.1900.TheQueenslandFlora.Brisbane.600pp.Baker,R.T.andSmith,H.theiressentialoils.47:193-215.G.1913.OntheAustralianmelaleucaandJournalProc.RoyalSoc.NewSouthWales.Bryant,L.H.1950.Corkfromthebarkofthepaper-barkedteatree.AustralianJournalofScience.12:182-183.Burki11,I.H.1935. }la1ay Peninsula.ADictionaryoftheEconomicProductsoftheLondon.pp.1431-1433.carter,M.RooiBurns, L. A.iCavinder,T.R.i Dugger, K.Roo;Fore, P. L.;Hicks,D.B.;Revells,H.L.; ?W. 1973.EcosystemsAnalysisoftheBigCypress andEstuaries.UnitedStatesEnvironmentalProtectionAgency.374pp.Chow, \<. T.andNg,S.K.1969.ApreliminarystudyonacidsulphatesoilsinWestMalaysia.MalaysianAgriculturalJournal.47:253-67.Coaldrake,J.E.Queensland.1961.Ecosystemsof the coastallowlandsofsouthernCSIROBulletin#283.138pp.Corner,E.J.H.1951. Hayside PrintingOffice,singapore.TreesofMalaya,Vol.I.772pp.GovernmentCoulter,J.K.1952.Gelamsoils. AgriculturalJournal.35:22-35.Craighead,F.C..,Sr.1971.TheTreesofSouthFlorida.UniversityMiamiPress,CoralGables.212pp.Curran,C..E..; S..L.;Bray1 rl.H. 1934..Thepulpingofcajeput,white mangrove, Australianpine, pinebythesulphateprocess.PaperTradeJournal.98:44-97.Dastur,J.F.1951.UsefulPlantsof India andPakistan. Bo9bay. 146pp.148

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149Davis,J.H.1943.ThenaturalfeaturesofsouthernFlorida.FloridaGeol.SurveyBulletin#25.Demaree,D.1932. Submerging experimentswithTaxodium.Ecology.13:258-262.Dickson,R.E.andBroyer,T.C.1972.Effectsofaeration,watersupply,andnitrogensourceonthegrowthanddevelopmentoftupelogumandbaldcypress.Ecology.53:626-634.Dineen,J.W.1972.LifeintheTenaciousEverglades.InDepthport:CentralandSouthernFloridaFloodControlDistrict.Re1:1-12.Elton,C.S.1958.TheEcologyofInvasionsbyPlants w,d Animals.JohnWiley,NewYork.199pp.Ewart,AJ.tory.andDavies,o.B.1917.London.pp.291-302.TheFloraoftheNorthernTerri-Galloway,R.w.;Gunn,R.H.;andStory,R.1970.LandsoftheMitchell-Normandyarea,Queensland.CSIROLandRes.Series#26.101pp.Guenther,E.1950.TheEssentialOils.VanNostrand,NewYork.211pp.Hofstetter,R.1973.Anecologicalstudyoftheeffectsoffireonthewetprairie,sawgrassglades,and communitiesofSouthFlorida.SouthFloridaEnvironmentalReport.53pp.Jacobson,M.1958.Insecticicesbook#154.299pp.Jakimova,T.V.1965.Effectofseedsofsubtropicalplants.p.94-97.(Fromabstract). from Plants.USDAAgricultural stratificationonthegerminationofBjull.Glavn.Bot.Sada.#54.Klein,H.;Schneider, ..J.;HcPherson,B. F. ;andBuchanan,SomehydrologicandbiologicaspectsoftheBigCypressdrainagearea,southernFlorida.USGSReport.#70003.T.J.1970.Swamp94pp.Langdon,G.o.1955.Silvicalcharacteristicsofbaldcypress.USDAForestServiceStationPaper #44. 7pp.Leighty,R.G.1954.Series1942#8.Soil Survey ofCollierCounty,Florida.72pp. USDA Long,R.W.and o.1971.AsityMiamiPress,CoralGables.FloraofTropicalpp.641-42.Florida.Univer-Louve1, H. 1951. Notes onthe easte::::-nHadaqascar forests.Rev.Int.Bot.App1. Trap.31:185-196. :-jat toon, \'1. R.1915. Thesout[lE:r:l Cypress. USDA Bulletin272. 74 pp.

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150 NcCoy, J.1972.Hydrologyof ",estern CollierCounty.USGSOpenFileReport#72018.117pp.Meskimen,G. F. 1962.ASilvicalStudyoftheMelaleucaTreeinSouthFlorida.UniversityofFloridaMaster's Tnesis. 177pp.Mortan,J.F.1966.Thecajeputtree--aboonandanaffliction.EconomicBotany.20:31-39. Nortan, J.F.1969.Someornamental excretingrespiratoryirritants.Proc.Flor.StateHort.Soc.82:415-421.Neal,M.C.1948.InGardensofHawaii.Honolulu.pp.565-66.Neybergh,A.G.1953.SomeplantstheeastoftheBelgiumCongo.(Fromabstract).grownfortheiressentialoilsinBull.Agric.Congo.BeIge.14:1-40.Odum,H.T.York.1971.Environment,Power,andSociety.331pp.John NewRuttner,F.Press.1963.FundamentalsofLimnology.UniversityofTorontoToronto.295pp.Sachet, N. H.1953.Sci.Congress.ThevegetationofMelanesia.4:42-45.Proc.EighthPacificSchory,E.A.1958.ThecajeputtreeinFlorida.Carib.Forester.19:50-55.Smiley.1973.FromBancroft,L.Exotic?lantControlPlan.EvergladesNationalPark.37pp.Swain,E.H.F.Brisbane.1928.TheTimbersandForestProductsofQueensland.pp.175-76. Ihlks, K.NSW.1953.Paperbarkasasourceofcork.Tech.NotesFor.Corom.,6:10-11. L.USDA.1967.ForestsofSoutheastAsia,PuertoRico,andTexas.Washington.410pp.

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151BIOGRAPHICAL SKETGi RonaldLewisMyerswasborninPaloAlto,CaliforniaonApril6,1946.HegraduatedfromMorrisHillsRegionalHighSchoolin Rockaway, NewJerseyin1964.HereceivedaBachelorofSciencedegreeinForestryfromtheUniversityofMontanain 1969. Afterworkingfor t\'lO yearsasaPeaceCorpsVolunteerinHonduras,hewasemployedbytheNationalParkServiceasaParkTechnicianinEvergladesNationalPark.In1973hewasadmittedtotheMasterofScienceProgramintheDepartmentofBotanyattheUniversityofFlorida.

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Botany {/ JohnJ.Ewel,ChairmanAssistantProfessorofIcertifythatIhavereadthisstudyandthatinmyopinionitconformstoacceptablestandardsofscholarlypresentationandisfullyadequate,inscopeandquality,asathesisforthe deRree ofMasterofScience.IcertifythatIhavereadthisstudyandthatinmyopinionitconformstoacceptablestandardsofscholarlypresentationandisfullyadequate,inscopeandquality,asathesisforthedegreeofMasterofScience.. .'HowardT.OdumGraduateResearchProfessorofEnvironmentalEngineeringIcertifythatIhavereadthisstudyandthatinmyopinionitconformstoacceptablestandardsofscholarlypresentationandisfullyadequate,inscopeandquality,asathesisforthedegreeofMasterofScience.DanielB. Ivard AssociateProfessorofBotanyThisthesiswassubmittedtotheGraduateFacultyoftheDepartmentofBotanyintheCollegeofArts and SciencesandtotheGraduateCouncil,andwasaccepted as partialfulfillmentoftherequirementsforthedegreeofMasterofScience. Jo'.arch 1975Dean,GraduateSchool

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