Assessing patterns and processes of landscape change in Okefenokee Swamp, Georgia

866 Pages·1998·33.9 MB·English

by  Loftin, Cynthia Smith

ASSESSINGPATTERNSANDPROCESSESOFLANDSCAPECHANGE
INOKEFENOKEESWAMP,GEORGIA
By
CYNTHIASMITHLOFTIN
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPAR-HALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
-4 1998
Copyright1998
by
CynthiaSmithLoftin
Tomyfamily:yourlove,patience,andencouragementmadethisworkpossible.
Inmemoryofmyfriend,MillicentQuammen,whowasaninspiration.
ACKNOWLEDGMENTS
Iamindebtedtomanyindividualswhocontributedtothiswork. Myacademic
advisorycommitteeprovideddirectioninmygraduatestudies,whichhascontributedto
mycontinuingdevelopmentasascientist. Theencouragement,tolerance,interest,and
counselofmyadvisor,Dr.WileyKitchens,permittedmetoexplorethoroughlymy
researchtopic,whichcontributedsignificantlytoitssuccessfulconclusion. Iamgrateful
forhiscontinuedconfidence. Dr.RamonLittellassistedwithdesignandanalysesofthe
vegetationspecies-hydroperiodandseedbankstudies;Iappreciatehispatience,time,
andassistance. Dr.JackPutz'skeen,editorialeyeforcedmetoclarifymanyaspectsof
thisdocument;histhoroughnessandfranknessareappreciated. Dr.GeorgeTannerand
Dr.LoukasArvanitiscontributedperspectivesandsuggestionsthatimprovedthis
dissertation. Iwanttothankthemfortheirinterestandtime. Dr.FranklinPercival
attendedmydefenseandprovidedthoughtfulandhumorousdiscussionthroughoutmy
doctoralprogram;Iappreciatehistimeandencouragement.
Manystudents,technicians,andfriendsassistedwithfieldwork,compilationof
GISandspreadsheetdatabases,andGISmodeldevelopmentandanalyses. Mysincere
appreciationisextendedtoC.Depkin,J.Brookshire,P.Owen,D.Evenson,D.O'Neill,
K.Williges,N.Ansay,P.Gonzalez,J.Aufmuth,J.Kitchens,J.Halblieb,andJ.Loftinfor
theirtirelessdedication. B.RaspberryoftheUSFWSassistedwiththeGPStopography
iv
survey;withouthisinvolvement,thehydrologystudywouldnothavebeenpossible. C.
TrowellmadehissummariesoftheOkefenokeeSwamphumanhistoryreadilyavailable;
Iwanttothankhimforbringingmanydetailstomyattention. Fellowgraduatestudents
andcoopunitemployeesL.Brandt,J.Silveira,C.Allen,K.Rice,A.Garmestani,W.
Bryant,D.Hughes,andB.Feslercontributedthoughtfuldiscussion,administrative
assistance,andmuch-neededlevity. L.Pearlstineguidedmethroughmyinitialforay
intotheworldofGIS,andW.Hydeprovidedexcellentcomputersystemsmanagement;I
amgratefulfortheirpatience.
ThestaffoftheOkefenokeeNationalWildlifeRefugedeservemydeepest
gratitudefortheirassistance. Theypermittedunlimitedaccesstorecordsandtheswamp,
aswellasassistedinGPSsurveys,waterlevelrecordermaintenance,andprovided
housingandequipmentuponrequest. S.Reeves,S.Aicher,L.Mallard,J.Burkhart,S.
Davis,R.Phernetton,T.Hiding,S.Jones,andC.Thompson,aswellasmanyothers,are
dedicatedstewardsofthatnaturaltreasure. ForesightoftheUSFWSandrefuge
managerstorecognizethatastudyoftheeffectsoftheSuwanneeRiversillonthe
swamphydrologyandecologywasneededandtoprovidesufficientfundingtoaddress
thesalientquestionswasintegraltoinitiationofthisstudy.
Myfamilycontinuestogiveencouragementandlove,whichhavefueledme
throughoutthiseffort;IwanttothankDorothyforherpatient,lovingcareofSteven,and
Kellyforherfriendshipandsuperbabysitting. Finally,IthankJimforhisunderstanding,
interest,andlove,whichenabledmetoattackthisproject,andwithoutwhomIcouldnot
havecompletedit,andSteven,whohasshownmeanotherfacetoflife.
TABLEOFCONTENTS
ACKNOWLEDGMENTS iv
LISTOFTABLES x
LISTOFFIGURES xx
ABSTRACT xxviii
CHAPTERS
1 THEOKEFENOKEESWAMPANDTHESUWANNEERIVERSILL 1
EcosystemHierarchiesandScales 5
DrivingFunctions 11
Disturbances,Heterogeneity,andSuccession 15
MonitoringLandscapeChange 19
TheOkefenokeeSwampEcosystem 20
HumanModificationofOkefenokeeSwamp 28
2 DATABASEORIGINANDDEVELOPMENT 34
DataSourcesandExtent 34
SwampWaterLevelData 36
WaterLevelRecorderPerformance 39
EstimationofMissingWaterLevelData 71
PrecipitationGaugeNetworkAssessment 83
Background 83
Methods 87
ResultsofPrecipitationNetworkAssessment 89
DiscussionofPrecipitationNetworkAnalysis 106
EstimationofMissingPrecipitationData 107
EstimationofEvapotranspiration,Inflow,andOutflowData 108
VI
SwampBasinDelineationandCharacterization 120
EffectsoftheSuwanneeRiverSillonSwampWaterLevelConditions 130
TopographySurface 146
CollectionofPointElevationData 150
SurfaceInterpolation 160
TopographySurfaceDescriptionandTrends 164
SatelliteImageryClassificationandAccuracyAssessment 172
ImagePreparation 173
ImageClassification 176
ImageClassificationAccuracyAssessment 178
ImageClassificationandAccuracyResults 193
InterpretingtheAccuracyAssessment 199
ApplyingImageClassificationProcedures 202
OKEFENOKEESWAMPHYDROLOGYMODEL 207
Introduction 207
Methods 209
ModelObjective 209
ModelOverview 210
ModelDataSources 220
Precipitation 220
Evapotranspiration 221
CreekInflowVolumes 221
RiverOutflowVolumes 222
WaterDepthandTopographicSurfaces 223
DataSurfacesUsedforModelAssessment 223
ModelManipulationandAssessment 225
WildfiresintheAreaAffectedbytheSuwanneeRiverSill 227
VegetationintheAreaAffectedbytheSuwanneeRiverSill 228
Results 229
AreaAffectedbytheSuwanneeRiverSill 229
ModelAccuracy:1980-1993 229
ModelResponsestoSillManipulations 267
RegionalHydrologicTrends 314
SystemSensitivities 348
WildfireOccurrence 361
VegetationChange 364
Discussion 375
ModelPerformance 375
EffectsoftheSuwanneeRiverSill 379
SystemSensitivities 382
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1
4 LANDSCAPELEVELVEGETATIONCHANGESINOKEFENOKEE
SWAMP 385
Introduction 386
DynamicsofSwampVegetation 386
SillAffectedVegetationChange 390
Methods 391
LoggingTramlines 391
Pre-LoggingVegetation(1850-1890) 395
Post-LoggingVegetation(1952) 398
17YearsWith-Silland22YearsPost-FireVegetation(1977) 410
30YearsWith-Silland35YearsPost-Fire(1990) 411
WildfireBurnAreaMaps 411
MapComparisons 415
Results 415
OverallChangesinVegetationDistributionsandComposition 415
LoggingImpacts 428
FireandVegetationChange 436
VegetationChangesintheAreasAffectedbytheSuwanneeRiver
Sill 438
Discussion 465
5 FIREINOKEFENOKEESWAMP 483
Introduction 483
Methods 488
WildfiresandPrescribedFires 488
WildfireOccurrencesandVegetationTypes 491
Results 492
FireSizes,Frequencies,andCauses 492
VegetationChangesWhereFiresOccurred 505
VegetationChangesRegardlessofFireOccurrence 514
WildfireandLogging 530
RecurrenceofFires 53
FireOccurrenceandWaterLevels 532
FireandtheSuwanneeRiverSill 541
Discussion 555
6 RELATIONSHIPSOFOKEFENOKEESWAMPVEGETATION
DISTRIBUTIONSANDTHEHYDROLOGICENVIRONMENT 564
Introduction 564
Methods 568
vm
:
VegetationSampling 568
PreparationofHydrologicData 574
AnalysisofVegetationData 579
Results 585
Species'Environments 585
Species'EnvironmentsandModeledHydrologicChanges 681
Discussion 681
Species'AssociationsandtheHydrologicEnvironment 681
VegetationChangesDueSillImpoundmentEffects 697
7 RESPONSEOFTHEOKEFENOKEESWAMPSEEDBANKTO
ALTERATIONSINTHEHYDROLOGICENVIRONMENT 702
Introduction 702
Methods 707
SeedBankSampling 707
AnalysisofSeedBankEmergenceData 712
Results 713
Species'Responses 713
TrendsinResponsetoHydrologicConditions 732
Discussion 744
WetlandSeedBankCompositionandVegetationCommunity
Dynamics 744
EffectsoftheSuwanneeRiverSillontheOkefenokeeSwampSeed
Bank 757
8 SUMMARYANDCONCLUSIONS 760
HumanActivityintheOkefenokeeSwamp 761
OkefenokeeSwampHydrology 764
OkefenokeeSwampVegetation 766
TheOkefenokeeSwampLandscape 768
APPENDIXA SUWANNEERIVERSILLAUTHORIZATIONBYCONGRESS 770
.
APPENDLXB COMPUTERMODELCODEFORHYDRO-MODEL 772
APPENDIXC VEGETATIONTRANSECTLOCATIONS 815
LISTOFREFERENCES 819
BIOGRAPHICALSKETCH . 835
IX
LISTOFTABLES
lahie page
1-1. Human-causedmanipulationsofOkefenokeeSwampvegetationand
topographyoccurringduringthepast150years 29
2-1. Waterlevelrecorderelevationsandstaffcorrections,operatingperiod,and
precipitationgaugelocations 40
2-2. SummaryparametersofwaterlevelrecordersinstalledatOkefenokeeNational
WildlifeRefugeduring12-5-1979through6-15-1995. Elevationsarein
metersabovemeansealevel. BasindelineationisdiscussedintheSwamp
BasinDelineationandCharacterizationsection 66
2-3. Summaryofwaterlevelandprecipitationrecorderperformanceduring
12-5-1979through6-15-1995atOkefenokeeNationalWildlifeRefuge 68
2-A. Summaryofwaterlevelrecorderperformanceproratedtotheinitialoperating
period(1054days) 72
2-5. Bestcorrelationpairsandregressionequationsusedtoestimatemissingwater
levelrecorderdataduring1941-1995 75
2-6. Dailyaverageprecipitationestimatedwithmeasurementsmadedaily,and
approximatedwithbiweeklyormonthlycalculationsofdailyaverages
during31March1992-3July1995 88
2-7. Stratumandstationvariancesandcovariancesofdailyprecipitationestimates,
averagedbyday,biweekly,andmonthlyduring31March1992-3July1995.
Symbologyisdefinedinthechaptertext 90
2-8. Relative,spatial,andtotalvarianceswithintheprecipitationgaugenetwork,
networkaccuracywithvariousrecorderdensities,andsuggestedstrata
allocationofprecipitationgauges 95