QuantifyingforestfireimpactsinSabangaupeatswamp
forestandtheconsequencesforBorneanorangutan
densityandhomerange
ShariLynnMang
StudentNumber:660051446Supervisor:Dr.FrankvanVeen
UniversityofExeter,CollegeofLifeandEnvironmentalSciencesMasterofScienceDissertation
August2017
TargetJournal:BiologicalConservation
Biologicalconservationisaleadingjournalinconservationbiologyandfocusesonresearchthatinformsand
advances conservation.My research examining how the ranging and density dynamics of orangutans are
impactedbyforestfiresmeetsthejournalsaimsofpublishingresearchfocusedon“theconsequencesofhuman
action for diversity” and articles “that contribute to biological…. dimension of conservation and natural
resourcemanagement”. As Bornean orangutans are an endangered species and forest fires are linked to
humanactivity,myresearchiswellsuitedforthis journal’saudience.Biologicalconservationisalsoawell-
regardedjournal,withthethirdhighestimpactfactorinthefieldofbiodiversityconservation.
TableofContents
Abstract…………………………………….………………………………………….……………………………………………………….11.Introduction………………………………………….…………………………………….……………………………………………22.Methods………………………………………….………………………………………….…………………………………………….4
2.1Studyareaandspecies………….………………………………………….………………………………………..52.2Estimatinghabitatlossduetofire………….………………………………………….……………………..5
2.2.1Data.………….………………………………………….………………………………………………………..52.2.2Landcoverclassification…….………………………………………….………………………………..6
2.3Orangutandensity………….………………………………………….……………………………………………….82.3.1Data………….………………………………………….…………………………………………………………82.3.2Statistics………….………………………………………….…………………………………………………..9
2.4Orangutanhomerange………….………………………………………….……………………………………..102.4.1Data………….………………………………………….……………………………………………………….102.4.2Analysis………….………………………………………….………………………………………………….112.4.3Statistics………….………………………………………….…………………………………………………11
3.Results…………………………………….………………………………………….……………………………………………………113.1Orangutandensityandchangeinforestcover………….…………………………………………..11
3.1.1Changeinforestcoverduetofire..………………………………………….…………………….113.1.2Orangutandensity………….………………………………………….………………………………….153.1.3Changeinorangutandensityandforestcover………….……………………………….....17
3.2Orangutanhomerange………….………………………………………….……………………………………..204.Discussion………….………………………………………….……………………………….……………………………………….22
4.1Changeinforestcoverduetofire.………………………………………….……………………………...234.2Orangutandensityandchangeinforestcoverduetofire……….…………………………..24
4.2.1Overallchangesindensityandforestcover……….………………………………………….244.2.2Variationindensityandforestcoverchangesamongsub-habitats……….………254.2.3Displacementandchangeinorangutandensity……….……………………………………26
4.3Orangutanhomerange………….………………………………………….……………………………………..294.4Long-termeffects………………………………………………………………………………………….....304.5Futureresearch………….………………………………………….………………………………………………….31
5.Conclusions………….………………………………………….……………………………………………………………………..32Acknowledgements………….………………………………………….…………………………………………………………….33References………….………………………………………….……………………………………………………………………………34Appendix1:SupplementaryMethods………….………………………………………….……………………………..43Appendix2:SupplementaryResults………….………………………………………….………………………………..57
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Abstract
Borneo’speatswampforestssupport thehighestdensityofBorneanorangutans,yetareoneof themost
vulnerable ecosystems to fire. Despite the prevalence and destruction of fires in Borneo, there is little
informationontheconsequencestoendangeredorangutans.Here,Iinvestigatedtheimpactsofforestfires
on the world’s largest remaining orangutan population in Sabangau, Central Kalimantan, Indonesia. I
estimatedhabitat lossdue to fire in2006,2010,and2015byclassifying landcover fromLandsat satellite
images.Icoupledthiswithorangutandensitydatafrom2002to2017fromtheBorneoNatureFoundation
(BNF)toevaluatelong-termandfireinducedchangesinpopulationdensity.Toassessshiftsinhomerange
sizeinunburntforestassociatedwiththe2015forestfires,Ievaluatedannualhomerangesfrom2003to2017
for20adultand10adolescentfemalesfromspatial-temporaldataprovidedbyBNF.Theresultsshowedan
830km2declineinforestcoverandanestimatedpopulationincreasefrom5154to8775frompre-fire2006
topost-fire2015.Thepopulationincreaseislinkedtothesignificantincreaseinorangutandensityfrom2002
to2017inthetall-interiorforestandmixed-swampforestinteriorandperimetersub-habitats.Ifoundthat
densitysignificantly increasedpost-fire in themixed-swampforestsub-habitat for9of the11 fireseasons
examined,includingthemajorfireeventsin2006and2015.However,homerangesizedidnotsignificantly
vary after the 2015 fire or between adult and adolescent females. This research shows that despite the
decreaseinforestcoverduetoforestfires,Sabangau’sorangutanpopulationhasincreasedinsizeanddensity.
Displacementofindividualsfromburntareasmaybecontributingintheincreaseddensity,buttheredoesnot
appear tobenegative impacts to thepopulationas it is still increasingand femalesmaintainstablehome
ranges. However, orangutans’ slow life history and long reproductive cyclemay delay the onset of some
consequences. Future burning of Sabangau’s forests should be mitigated to avoid compromised habitat
quality,overcrowding,andabreachofcarryingcapacity.
Keywords:Borneanorangutan,forestfire,Sabangau,peatswampforest,density,homerange
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1.Introduction
WhileBorneo’sforestshavesomeoftheworld’shighestbiodiversityandendemism(Woodruff,2010),Borneo
alsohassomeofthehighestratesofforestdegradation(Miettinenetal.,2011;Sodhietal.,2004)andmost
damagingforestfires(Taylor,2010).Indonesiahasalonghistoryofresourceextraction(Gaveauetal.,2014),
andsincethe1980s,peatswampforestshavebeenincreasinglydegradedbylegalandillegallogging(Tsujino
etal.,2016;Yule,2010),plantationdevelopment(Margonoetal.,2014;MiettinenandLiew,2010),drainage
andlanddevelopment(Yule,2010),andforestfires(Fieldetal.,2009). Indonesiacontainsoverhalfofthe
world’stropicalpeatswampforest(Pageetal.,2006)withalmost68,000km2historicallyfoundinKalimantan
(Posaetal.,2011).However,by2004only47%ofKalimantan’speatswampforestremained,11%ofwhich
wasprotected(Posaetal.,2011).Fortheunique,oftenendemicandendangered,floraandfaunasupported
bypeat swamp forests (Miettinenetal., 2012), thishas causeda severe lossofhabitat (Cochrane,2003),
alteredspeciescompositionandcommunitystructure(Sliketal.,2010),andreducedpopulations(Ancrenaz
etal.2016;Nijmanetal.,2008).
ForestfiresdonotnaturallyoccurinBorneo(Pageetal.,2002;Turetskyetal.,2015)butnowburn
annually(Chisholmetal.2016)largelyduetointentionallysetfires(Simorangkir,2007;Usupetal.,2004)and
reducednatural fire resilience fromyearsofhabitat lossanddegradation (Miettinenetal.,2012;Tacconi,
2016).ThemostsevereeventsarecorrelatedwithextremelystrongElNiño-SouthernOscillation (ElNiño)
episodes(Siegertetal.,2001;Yuliantietal.2012)thatcauseprolongeddrought,exacerbatingforests’reduced
fireresilienceandfacilitatingthespreadandintensityoffires(Chisholmetal.,2016;Fieldetal.,2009;Wooster
etal.,2012).Borneo’s2015fires,whichcoincidedwithastrongElNiñoandextremedrought(Yuliantietal.
2012; Tacconi, 2016), were theworst fires since the 1997-1998 El Niño fires (Chisholm et al., 2016) and
affected1.287millionhaofKalimantan’sforests(Tacconi,2016).
PeatswampforestsaresomeofBorneo’smostvulnerableecosystemstofire(Pageetal.,2009a;Posa
etal.,2011),aslogginganddrainageincreasethedensityofunderstoryspeciesanddeadvegetation(Siegert
etal.,2001),lowerthewatertable,anddryouttheforestfloorandlayersofpeatsoil,generatingabuild-up
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ofextremelyflammabledrysoil(LangnerandSiegert,2009;Turetskyetal.,2015;Wöstenetal.,2006).Peat
firesaredifficulttoextinguishastheypenetratedownthroughpeatlayerswheretheycanburnformonths
(Yule,2010),spreading laterally throughthe forests, ignitingabovegroundfires inareaswithno localheat
source(Chisholmetal.,2016;Usupetal.,2004).Consequently,speciesfarfromignitionsourcesarestillat
riskfromforestfires.This includesBorneanorangutans(Pongopygmaeus),whoarefoundattheirhighest
populationdensityinpeatswampforest(Russonetal.,2001;vanSchaiketal.,1995).
Habitatdegradation,includingforestfires(Chisholmetal.,2016;Drake,2015;Fieldetal.,2009),have
contributedtothe64%declineintheBorneanorangutanpopulation(Ancrenazetal.2016).Orangutans’slow
lifehistory,longinter-birthinterval(GaldikasandAshbury,2013;Leightonetal.,1995;Marshalletal.,2008),
and lowpopulationdensity (Johnsonetal.,2005;Morrogh-Bernardetal.,2003)makethemvulnerable to
stochasticeventssuchasfires(RijksenandMeijaard,1999).Althoughresearchislimitedontheimpactsto
orangutans, theyarehighlysensitive tosomeof thepossibleconsequencesof fires, suchas reduced food
resources (Cant, 1980; Carne et al., 2015; Felton et al., 2003; Husson et al., 2009), degraded ecosystem
structure(Feltonetal.,2003),andrefugeecrowding(RijksenandMeijaard,1999).However,theimpactwill
varywithfireintensity(Pageetal.,2009b),thepopulation’ssizerelativetocarryingcapacity,andecosystem
recoverypotential(Chisholmetal.,2016).Longtermpopulationconsequencesmayarise,asadecreasein
theiralreadylowbirthrate(GaldikasandAshbury,2013;Wichetal.,2008)duetoincreasedcompetitionand
reducedresourceswillmake itdifficult torecover fromthepotential indirectordirect increasedmortality
fromfires(Marshalletal.,2008).
Despitethefrequencyanddevastationofforestfires,there isa lackofresearchonthe impactsto
orangutanpopulations.Toaddressthisknowledgegap,thisresearchaimedtoquantifytheeffectsoffireon
theworld’slargestremainingorangutanpopulationinSabangau,CentralKalimantan,Indonesia.Todothis,I
1) estimated habitat loss due to fire and the associated change in population, 2) assessed the long-term
populationdensitytrendswithafocusonthechangeindensityaftereachfireseason,and3)assessedwhether
female home range size differed before and after a fire in a neighbouring unburnt area. I predicted that
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orangutandensitywouldincreaseandfemalehomerangesizewoulddecreasefollowingafire.Ifocusedon
females’homerangesas femalesarephilopatric (Morrogh-Bernardetal.,2003;SingletonandvanSchaik,
2002)withtemporallystableranges(Galdikas,1988;SingletonandvanSchaik,2001;Wartmannetal.,2010)
andoftenremainintheirestablishedrangeintheeventofdisturbance(vanNoordwijketal.,2012).
2.Methods
2.1Studyareaandspecies
ThisstudyfocusesonSabangauNationalParkinCentralKalimantan,Indonesia(2°19’Sand113°54’E).Thearea
usedfortheorangutandensityandforestcoveranlaysisisdefinedastheregionboundbytheSabangauand
KatinganRivers,whichcoversanareaof6996km2(Figure1).Sabangauisapeatswampforest(PSF)madeup
offoursubhabitats:mixed-swampforest(MSF),low-poleforest(LPF),tall-interiorforest(TIF),andvery-low
canopy(VLC).Thehomerangeanalysisuseda9km2researchplotwithinSabangau’sMSFalongthenorthpart
oftheSabangauRiver.
SabangauisthelargestcontiguouspeatswampforestremaininginKalimantanandsupportsthe
largestorangutanpopulationintheworld(Singletonetal.,2004).Likeotherpeatswampforests,itisrichin
biodiversity,supportingpeatlandspecialistsandmanyotherendangeredspecies(Morrogh-Bernardand
Husson,2002;Hussoneta.,2007).Inadditiontotheorangutansub-speciesP.p.wurmbii,Sabangausupports
Borneanwhite-beardedgibbons(Hylobatesalbibarbis),cloudedleopards(Neogelisnebulosi),andrhinoceros
hornbills(Malacocinclaalbogulare)(Pageetal.,2006).
Sabangau experienced selective logging prior to its national park designation in 2004 (Morrogh-
Bernard,2009).However,itisstillatriskfromillegallogging(Tsujinoetal.,2016;Wichetal.,2012;Yule,2010)
anddegradationbyforestfires,particularlyastherehasbeenextensivedrainageofthepeatforconversion
to plantations and logging (Rijksen andMeijaard, 1999). Fires occur annually in Sabangau, but themost
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extensivefiresinrecentyearshavebeenin2006,2010,and2015(Morrogh-Bernard,pers.comm.;Tacconi,
2016;Yuliantietal.,2012).
Figure1:The6996km2Sabangaustudyarea(blackoutline)boundbytheKatinganandSabangauRiversandthe9km2researchplot(redstar)inSabangauNationalPark,CentralKalimantan,Indonesia.2.2Estimatinghabitatlossduetofire
BelowisasummaryofthemainmethodsIusedtoestimatehabitatlossduetofireusingsatelliteimagesand
landcoverclassificationtools.Formorecomprehensivedetailsofthemethods,pleaseseeAppendix1.
2.2.1Data
IusedimagesfromtheLandsatsatelliteseriestoclassifylandcoverbeforeandaftereachfireeventforthe
threeyearsofinterest:2006,2010,and2015.ImagesarefreelyavailablefromtheUnitedStatesGeological
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Survey (USGS) Earth ResourcesObservation and Science (EROS) Data Centre via their Earth Explorerweb
interface(http://earthexplorer.usgs.gov/).
For each year, I examined 8-day composite images of active fires from theModerate Resolution
Imaging Spectroradiometer (MODIS) satellite product MOD14A2 acquired from Earthdata
(https://earthengine.google.com)todeterminethestartandendofeachfireseason.Basedonthisevaluation,
IonlyselectedLandsatimagesfromDecembertotheendofJuly,astherewerenofiresobservedinSabangau
duringthosemonths,whichwassupportedbymonthlyfirehotspotanalysisdonebyYuliantietal. (2012).
Whenpossible,Ipreferentiallyselectedpre-fireimagesatthebeginningofthefireseason(i.e.July)andpost-
fireimagesattheend(i.e.December).TheimagesanddatesIusedforclassificationareinAppendix1,Table
A1.1.
2.2.2Landcoverclassification
Priortoclassification,IradiometricallycorrectedtheimagesinENVI5.4toenabletemporalcomparison(Lu
andWeng,2007;Youngetal.,2017).IthenprojectedtheimagestotheUniversalTransverseMercator(UTM)
project,Zone50South inArcMap10.5,which Iusedfortheremainderof theanalysis. Iusedamaximum
likelihoodsupervisedclassification(MLC)approach(Lietal.,2014;LuandWeng,2007)toclassifytheimages
into nine land cover classes (Table 1). Following the classification, I processed the images to improve the
qualityoftheclassification(Stefanovetal.,2001;LuandWeng,2004)byreducingthenoiseintheimage(Lu
andWeng,2007;Wijedadaetal.,2012)andidentifyingthelandclassescoveredbycloud,cloudshadow,haze,
andnullclassesandconvertedthemtotheappropriateclassification.
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Table1:Descriptionoflandcoverclassesusedintheclassification.Category LandCoverClass Description
Forest Peatswampforest(PSF)
Undisturbedpeatswampforest,oldre-growthwithminimaldisturbancefromfireorlogging;includessomeoldsecondaryforestthatwaspreviouslyloggedandcannotbedistinguishedfromundisturbedpeatswamp
Non-Forest
Burnscar Recentlyburntarea;bareearthwithlittletonovegetation.
Degradedforest
Peatswampforestthathasbeendegradedbyloggingand/orfire.Includesareasofopencanopypeatswampandareasofrecent,minimalvegetationre-growththatexhibitsdistinguishabletextureandreflectancefromprimaryandoldre-growthpeatswampforest.
Sedge Areasofnon-woodyvegetationandtheriversandfloodedpeatcontainedwithinthem.
Water Riversandlakesincludingseasonallyfloodedareas.
NoData
Cloud Cloudthatwasnotremovedbythecloudmask.
Haze Thin,wispycloudthatwasnotremovedbythecloudmask.
CloudShadow Cloudshadowthatwasnotremovedbythecloudmask.
Null SLC-offnodataareasthatwerenotcorrectedbythelocalhistogrammatchingmethod.
To evaluate land cover changeswithin each sub-habitat, I used Ehlmer Smith and Ehlmer Smith’s
(2013) classification and shapefiles which divide Sabangau in four sub-habitats: MSF, LPF, TIF, and VLC
(Appendix1,FigureA1.1).IfurtherdividedMSF(referredtoasMSF-total[MSF-T])intoMSF-interior(MSF-I)
andMSF-perimeter(MSF-P)tocoincidewiththeorangutandensitydata.
AsSabangau isaprotectedarea, Iassumedthatallobservedchanges in forestcoverweredue to
forestfire,however,IacknowledgethatillegalloggingmayoccurinSabangau(Tsujinoetal.,2016;Wichet
al.,2012;Yule,2010).Iftheloggingwasextensiveenough,itmaybeclassifiedasdegradedforestbytheMLC,
but as illegal activityhas slowed in Sabangau (OuTrop,2012), itwould likelybe small relative to thearea
damagedbyfire.
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2.3Orangutandensity
2.3.1Data
Orangutandensitydatafrom2002to2017intheformofnestcountswasprovidedandisownedbySimon
Husson. It was collected monthly for MSF from the 9 km2 research plot along the Sabangau River. Two
transectswereusedforeachMSF-IandMSF-Pthatwere6kmand7kmlong,respectively.DataforTIFwas
gatheredonceayearin2002-2005,2008,2011,2013,and2016andforLPFin2002,2004-2006,2008,2009,
2011,and2013.Theseareasweresurveyedduringthedryseason(JunetoSeptember)fromvariouslocations
each year along two transects each that varied in length from 4 - 5.5 km and 6 – 8 km for TIF and LPF,
respectively.TheydidnotgatherdensitydatafromVLC.
Iconvertedthenestcountstoorangutandensity(individuals/km2)followingthemethodsinMorrogh-
Bernardetal.(2003)andusedtheSabangauspecificparametersprovidedinHussonetal.(2008).
Ifirstcalculatednestdensitiesfromnestcountswiththeformula:
Nd=Nc/(lxw)
WhereNd=nestdensity,Nc=nestcount,l=transectlengthandw=transectwidth(0.042kmforalltransects).
Ithenconvertednestdensitytoorangutandensityusingtherelationship:
D=Nd/(pxrxt)
WhereD=orangutandensity(individuals/km2),p=proportionofnestmakersinthepopulation(0.89),r=rate
ofnestproduction(1.16/individual/day),andt=timeanestremainsvisible(365days)(Hussonetal.,2008;
Morrogh-Bernardetal.,2003).
Togenerateacompletelong-termdensitydataset,Iestimatedorangutandensityforthemissingyears
inTIFandLPF.IfirstcalculatedtheratiosbetweenMSF-IandMSF-PwithbothTIFandLPF.Iusedtheaverage
foreachratio(i.e.LPF:MSF-IandLPF:MSF-P)tomaketwodensityestimatesforeveryyear.Ithencalculated
thedeviancefromthetruedensityinyearswithTIFandLPFobservationsandusedtheratiothatledtothe
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lowest average deviance, which was TIF:MSF-P and LPF:MSF-I, to estimate the missing density values
(Appendix1,TableA1.4).
AstheMSFdatawasgatheredmonthly,Iusedittoevaluatevariationinpre-andpost-fireorangutan
density.Foreachyearfrom2002to2016,IdividedtheMSF-T,MSF-I,andMSF-Pdataintopre-fire,during-
fire,andpost-firecategories.ThefireseasoninBorneovariesannually(LangnerandSiegert,2009),butusing
theMODISsatelliteproductMOD14A2(Section2.2.1)IfoundSabangau’sfiresoccurredfromAugusttothe
endofNovember.ThisagreeswithYuliantietal.(2012)whofoundAugust,September,andOctobertohave
thehighest incidenceof fires inCentralKalimantan.Accordingly, Iassigned ‘during-fire’asAugustthrough
November,‘pre-fire’asDecemberthepreviousyearthroughJuly,and‘post-fire’asDecemberthroughJuly
thefollowingyear.
2.3.2Statistics
IperformedallstatisticalanalysisinSPSS(version24).Aftertestingorangutandensitydatafornormality,Iran
alinearregressionforeachsub-habitattotesttheinfluenceoftimeonorangutandensity.Ialsousedalinear
regressiontodeterminewhetherdensitywasaffectedbyhabitattypeovertime;Ifollowedthiswithaone-
wayANOVAandTukeyHSDposthoctodeterminewheresignificantvariationoccurred.
Asdensity increasedover time, I used the linearequation tode-trend thedataby calculating the
residualdensityforMSF-P,MSF-I,andMSF-T.Fortheseregions,Iperformedalinearregressiontodetermine
whetherorangutandensitywasinfluencedbyforestcover,ascalculatedfromtheMLCforpre-andpost-fire
2006,2010,and2015.Iusedapairedt-testtoevaluatevariationbetweenpre-andpost-fireorangutandensity
ineachMSFsub-habitat from2002 to2016.Although there isa linear increase indensity throughout the
study,Iusedthemeasuredorangutandensityforpairedt-testanalysis;thelong-termdensityincreaseshould
minimallyinfluencethe8-monthpre-andpost-fireperiodsasorangutans’havealong-lifehistoryandinter-
birthinterval(Leightonetal.,1995;Marshalletal.,2008).
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2.4Orangutanhomerange
2.4.1Data
Todetermineorangutanhome range size, I used followdataprovidedandownedbyDr.HelenMorrogh-
Bernard of the Borneo Nature Foundation (BNF) that was collected from September 2003 toMay 2017.
Surveysweredoneinthe9km2researchplotalongtheSabangauRiver.Observersusedoneof12N-Sor12E-
Wtransectstolocateanorangutanandthenfollowedtheindividual,recordingtheirlocationonaGPSevery
30minutesforfollowsbetween2003and2011,andevery5minutesfrom2011onward.Observerstracked
anindividualforamaximumoftenconsecutivedaysoruntillost.Thenumberofsurveysdoneeachyearis
variable,withamaximumof259in2005andaminimumof57in2010.ToconverttheGPSdatafrompoint
datatodecimaldegrees,IusedExpertGPS6.0.
Thedataincludes10adolescentfemales(ADF)and20adultfemales(AF),2ofwhichwerefollowed
fromadolescenceintoadulthood.Iseparatedindividualsbyage-classfortheanalysisashomerangesizevaries
amongorangutanage-sexclasses(Galdikas,1988;Morrogh-Bernard,2009;SingletonandvanSchaik,2001).
ADFaredistinguishedfromAFinthattheformerarenon-sexuallyactiveandliveindependentoftheirmother,
whilethelatteraresexuallyactiveandoftenaccompaniedbyaninfant(Morrogh-Bernard,2009).
I used theaforementionedMOD14A2 images (Section2.2.1) todateSabangau’s2015 fire season,
whichIdeterminedtobefromAugust5thtoNovember8th,2015.Basedonthis,Iclassifiedeachorangutan
followaspre-fire(September9th,2003–August4th,2015),during-fire(August5th–November8th,2015),or
post-fire(November9th,2015–May18th,2017).Nofiresburnedinsidetheresearchplot(Morrogh-Bernard,
pers.comm.),buttwooccurredeastandsouthwestofthestudysite,bothlessthan1kmaway.
Iestimated individuals’ residencestatusbycalculating theirpresence index (Kj), as thenumberof
monthstheyweresighteddividedbythelengthofthestudy(SingletonandvanSchaik,2001). Icalculated
annualKj(JanuarytoDecember)tocapturechangesinresidencyovertime.For2015,Icalculatedannual,pre-
fire, during-fire, and post-fire Kj values.Using the Kj score, I classified individuals as Frequent (Kj ≥ 50%),
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Regular(25%≤Kj<50%),Occasional(4%≤Kj<25%),orRare(Kj≤4%)(Appendix1,TableA1.5).Iconsidered
FrequentandRegularindividualstoberesidentsofthepopulation.
2.4.2Analysis
ThedatawasprojectedintotheUniversalTransverseMercator(UTM)WorldGeodeticSystem(WSG)198450
South coordinate projection in ArcMap 10.5. I estimated individuals’ annual home range size using the
minimumconvexpolygonmethod(MCP)(Boyleetal.,2009;Hayne,1949).MCPlinkstheoutmostpointsto
generateavectorpolygonandiscommonlyusedtoestimateorangutanhomerange(Campbell-Smithetal.,
2011;Morrogh-Bernard,2009;SingletonandvanSchaik,2001;Wartmannetal.,2010).Togetanaccurate
estimateofhomerangesize,Ionlyanalyzedresidentsofthepopulationastheyhadthemostdataandshould
havestablehomeranges(Morrogh-Bernard,2009).
2.4.3Statistics
IperformedallstatisticalanalysisinSPSS(version24).AshomerangesizewasnormallydistributedforAFand
ADF,Iusedalinearregressiontodeterminewhetherthenumberoffollowsinfluencedanindividuals’annual
homerangesize.Ialsousedalinearregressiontoexaminewhetherhomerangesizewithineachage-class
variedovertime.Iusedagenerallinearmodel(GLM)totestwhetherhomerangesizevariedpre-topost-fire
andbetweenage-classes.Only4residentAF(Feb,Gracia,Indah,andIndy)weresampledpre-andpost-fire
2015, so Iuseda sign test todetermine if theiraveragehomerangesizevariedbeforeandafter the fire.
3.Results
3.1Orangutandensityandchangeinforestcover
3.1.1Changeinforestcoverduetofire
BasedontheMLC,2006hadthegreatestdecreaseinforestcoverat562.2km2followedby2015(510.3km2)
then2010(277.3km2)(Figures3,4,5;Appendix2,TableA2.1).Betweenfireevents,forestcoverincreased
butnevertopreviouslevels,leadingtoa14.8%decreaseinforestcoverbetweenpre-fire2006andpost-fire
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2015.Asaresult,thepercentoftheSabangauclassifiedaspeatswampforestdeclinedfrom80.4%to68.5%,
withtheremainderbeingpredominantlyclassifiedasdegradedforestandburnscars.Burninganddegradation
wereconcentratedaroundtheforestperipheryandalongrivers,sedge,anddevelopedarea.Althoughthe
percentincreaseinburnscarareawashigherin2006(282.4%)thanin2015(99.7%),thepost-fireburntareas
weresimilar(2006=897.4km2;2015=843.9km2)duetoextensiveburnscarspre-fire2015.Whileburnscars
oftenreplacedareasclassifiedaspeatswampforest, theyalsooccurred in regionspreviouslyclassifiedas
degraded.Frompost-fire2006topre-fire2010,sedgeexpanded(9.9km2to95.0km2)predominantly into
areaspreviouslyclassifiedasburnscarordegradedforest.However,therewasanoveralldecreasefrom62.4
km2to11.2km2bypost-fire2015withsedgebeingreplacedbyburnscarsanddegradedregions.
Figure3:LandcoverclassificationforSabangaupre-fire2006(07-06-2006)andpost-fire2006(04-07-2007)basedontheoutputfromtheMLC.Theblackstarrepresentsthe9km2researchplot.
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Figure4:LandcoverclassificationforSabangaupre-fire2010(10-02-2010)andpost-fire2010(13-06-2011)basedontheoutputfromtheMLC.Theblackstarrepresentsthe9km2researchplot.
Figure5:LandcoverclassificationforSabangaupre-fire2015(03-08-2015)andpost-fire2015(14-03-2016)basedontheoutputfromtheMLC.Theblackstarrepresentsthe9km2researchplot.
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Based on the sub-habitat division provided by Ehlmer Smith and Ehlmer Smith (2013), MSF-T
constitutes53.8%(3761.2km2)ofthetotalstudyarea,2137.2km2ofwhichisMSF-I.LPFisthenextlargest
sub-habitatat1907.0km2followedbyTIF(1044.6km2)andVLC(283.0km2).Figure6showstheproportionof
eachsub-habitatclassifiedasforestbytheMLCforeachperiod.Theremainderofeachsub-habitatconsists
ofnon-forestclasses,predominantlyburnscarsanddegradedforestwithminimalareaclassifiedassedgeand
water(Appendix2,TableA2.2).Withineachsub-habitat,MSF-Phadthegreatestpercentdecreaseinforest
covereveryyear(2006:28.9%;2010:13.3%;2015:22.0%)leadingtoanoveralldecreaseof44.9%bypost-fire
2015.TogetherwithhighannualforestcoverlossesinMSF-I(2006:14.7%;2010:7.4%;2015:14.8%),MSF-T
forestcoverdeclinedby29.9%.Theremainingsub-habitatshadmuchlowerannualandtotalchange;overall,
forestcoverinTIFandVLCdeclined5.9%and3.1%,respectively,andforestcoverinLPFincreasedby0.3%.
Figure6:Theproportionofeachsub-habitatthatwasclassifiedasforestinSabangauforpre-andpost-firein2006,2010,and2015.ValuesarebasedonlandcoverclassificationbytheMLC.
Frompre-fire2006topost-fire2015,theproportionofSabangau’stotalforestcoverwithinMSF-P
and MSP-I decreased due to their greater forest loss relative to the other sub-habitats (Figure 7). This
proportionincreasedinLPF,TIF,andVLC,withthelargestincreaseinLPFfrom0.31to0.37,representinga
15
17.7%increase.MSF-Psawthelargestdecline,from0.16to0.10,representinga35.3%decrease.Whilethe
proportionoftotalforestcoverdeclinedinMSF-I,itstillconstitutesthesecondhighestproportionat0.27in
post-fire2015.
Figure7:TheproportionofSabangau’sforestcoverineachsub-habitatforpre-andpost-firein2006,2010,and2015.ValuesarebasedonlandcoverclassificationbytheMLC.3.1.2Orangutandensity
Bothtimeandsub-habitatexplainasignificantamountofvariationinorangutandensity(R2=0.907,F(4,59)=
143.981,p< 0.001),with a significant difference between all sub-habitat pairs (MSF-P andMSF-I, F(3,60)=
53.595,p=0.005;allotherpairs:F(3,60)=53.595,p<0.001)exceptforMSF-IandLPF(F(3,60)=53.595,p=0.051)
(Figure8).Aswell,thelinearregressionshowedasignificantincreaseinorangutandensityfrom2002to2017
inallsub-habitatsexceptLPF(MSF-P:R2=0.812,F(1,129)=558.840,p<0.001;MSF-I:R2=0.715,F(1,129)=323.525,
p<0.001;TIF:R2=0.890,F(1,14)=113.101,p<0.001;LPF:R2=0.235,F(1,14)=4.298,p=0.057).
16
Figure 8: Annual orangutan density in each sub-habitat from 2002 to 2017.MSF-P andMSF-I are yearlyaveragesbasedonmonthlymeasurements.LPFandTIFaresingleannualmeasurements,withfilledcirclesbeing fieldobservationsandopen trianglesbeingestimatesbasedon the ratiosTIF:MSF-PandLPF:MSP-I.(MSF-PandMSF-I:n=4in2017;n=6in2015;n=8in2003,2007,2009,2011,and2016;n=9in2002,2004,2005,2006,2008,2010,2012,2013,and2014.LPFandTIF:fieldobservations:n=8;estimates:n=8)
TIFhad thehighestdensity through theentire studyaswellas thegreatest rateof change (0.118
individuals/km2/year). MSF-P andMSF-I experienced similar rates of change in density (0.066 and 0.072
individuals/km2/year,respectively),withMSF-Pmaintainingahigherdensitythroughout.Apartfrom2002and
2003,LPFhadthelowestorangutandensityandshowedlittleincreaseovertime(0.029individuals/km2/year).
Theresidualdensity for theMSFsub-habitatsshowsanoscillationwithinthe increasingtrends for
thesesub-habitats(Figure9;Appendix2,FigureA2.1).Thesingletrough,fromlate2008tolate2011,isflanked
bytwopeaks,themostrecentofwhichmaybeshowingthestartofadownwardtrend.Thispatternismost
prominentinMSF-I,withmorevariationintheresidualdensityinMSF-P.
17
Figure9:ResidualorangutandensityforMSF-TfromJanuary2002toMay2017(n=131).3.1.3Changeinorangutandensityandforestcover
Bycombiningtheorangutandensitydatawithestimatesofforestcover,IestimatedSabangau’sorangutan
populationpre-fire2006as5154individuals;bypost-fire2015,Iestimatethepopulationincreasedby3612
to8775individuals(Appendix2,FigureA2.2,TableA2.3).However,thisestimateexcludesindividualsinVLC,
astherewasnodensitydataforthissub-habitat.
Thechangeinpopulationandforestcoverisnotevenlydistributedthroughoutthesub-habitats.Over
thestudy,MSF-Phad the largestdecrease in the forestcover (24.2%)andpopulation (16.6%) (Figure10).
AlthoughtherewasadecreaseinforestcoverinMSF-I(17.6%)andTIF(5.7%),thepopulationincreasedin
bothby46.8%and96.3%,respectively.LPFwastheonlyareatoincreaseinforestcover(0.3%)andhadthe
greatestincreaseinpopulationat216.7%.
18
Figure10:Percentchangeinforestcoverandorangutanpopulationfrompre-fire2006topost-fire2015withineachsub-habitat.
Theunequalchangeinforestcoverandorangutandensityamongthesub-habitatsshiftedtherelative
distributionofSabangau’stotalforestcoverandorangutanpopulation(Appendix2,FigureA2.3).Although
LPFexperiencedasmall increase inforestcover,thischangecoupledwithdecreasedforestcover inother
areas,causeda17.7%increaseintheproportionofSabangau’stotalforestcovercontainedinLPF.Despite
theoverallincreaseinMSF-I’sorangutanpopulation,theproportionofthetotalpopulationthissub-habitat
supportsdecreasedby13.9%,whileitincreasedby86.0%and15.3%inLPFandTIF,respectively.Aswell,by
post-fire2015,MSF-Psupported51.0%lessofSabangau’sorangutanpopulationthanitdidpre-fire2006.
AlthoughthereisasignificantdecreasinglinearrelationshipbetweenorangutandensityinMSF-Tand
Sabangau’stotalforestcover,theamountofvariationindensityexplainedbythemodelislow(R2=0.297,
F(1,74)=31.208,p<0.001)(Figure11).ThisrelationshipholdsforMSF-PandMSF-Iaswell(Appendix2,Figure
A2.4).
19
Figure11:Relationshipbetweenaverageorangutandensity inMSF-TandSabangau’stotalforestcoverforpre-andpost-fire2006,2010,and2015.ForestcovervaluesarebasedonlandcoverclassificationbytheMLC,anderrorbarsrepresent95%confidenceintervals.(n=6for5061km2and5623km2;n=5forallothers)
The paired t-test on orangutan density grouped in 8-month pre- and post-fire periods showed
significantvariationbeforeandafter11fireeventsinMSF-T(Figure12;Appendix2,TableA2.4):2002(t(4)=
-3.062,p=0.038),2003(t(5)=-2.752,p=0.040),2004(t(5)=-8.044,p<0.001),2005(t(5)=4.124,p=0.009),
2006(t(5)=-5.731,p=0.002),2007(t(4)=-3.428,p=0.027),2008(t(4)=10.959,p<0.001),2009(t(4)=-4.824,p
=0.008),2011(t(4)=-10.119,p<0.001),2012(t(5)=-2.980,p=0.031),and2015(t(5)=-4.522,p=0.011).Of
theseevents, density increasedpost-fire in all but 2005and2008.A similarpatternholds true forMSF-P
(Appendix2,FigureA2.5,TableA2.5)andMSF-I (Appendix2,FigureA2.6,TableA2.6)with7and9years,
respectively,havingsignificantvariationbetweenpre-andpost-fireorangutandensity.
20
Figure12:Averagepre-andpost-fireorangutandensityinMSF-Tfrom2002to2016.Errorbarsrepresent95%confidenceintervals.Significantdifferencesareindicatedby*p<0.05;**p<0.01;and***p<0.001.(n=4in2016;n=5in2002,2007,2008,2009,2010,2013,2014,and2015;n=6in2003,2004,2005,2006,2011,and2012)3.2Orangutanhomerange
Whenalladultandadolescentfemalesinthedatasetwereconsidered,therewasasignificantrelationship
between home range size and the number of follows per year (R2 = 0.531; F(1,112) = 126.847; p < 0.001).
Althoughthisrelationshipweakenedwhenonlyregularandfrequentindividualswereconsidered(R2=0.328;
F(1,66)=32.262;p<0.001)andagainwithonlyfrequentindividuals(R2=0.174;F(1,23)=4.851;p=0.038),the
relationshipremainedsignificant(Appendix2,FigureA2.7).Tominimizetheinfluencethenumberoffollows
hadonhomerangesize,Iusedonlyfrequentandregularindividuals(i.e.residents)fortheanalysis.
Basedonthelinearregression,homerangesizedoesnotsignificantlyvaryfrom2003topre-fire2015
forAF(R2=0.020;F(1,34)=0.680;p=0.415)orADF(R2=0.150;F(1,17)=2.992;p=0.102)(Appendix2,Figure
A2.8).TheGLMcontainingthevariablesage-classandpre-andpost-fire2015didnotexplainasignificant
proportionofthevariationinrangesize(R2=0.301;F(3,15)=2.148;p=0.137).Theaveragehomerangesizefor
21
AFpre-firewas1.38km2(SD=0.43)andpost-firewas1.04km2(SD=0.17);forADFitwas0.90km2(SD=0.55)
and0.73km2(SD=0.39)pre-andpost-fire,respectively(Figure13).
Figure13:Averagehomerangesize(km2)pre-andpost-fire2015forresidentadultandadolescentfemale.Homerangesizedoesnotsignificantlyvarypre-topost-fireforAF(p=0.415)orADF(p=0.102).(AFPre-fire:n=7;AFPost-fire:n=4;ADFpre-fire:n=5;ADFpost-fire:n=3)
AlthougheachAFwithpaireddatahadasmalleraveragehomerangeafterthefire(Appendix2,Table
A2.7),thesigntest(alpha=0.0625)indicatedthechangeforthegroupwasnotsignificant(p=0.125)(Mpre-fire
=1.56±0.18SD;Mpost-fire=1.04±0.17SD).Figure14illustratesthevariationinFeb’sannualhomerangesize
from2010to2017.VariationintheannualhomerangesizeforGracia,Indy,andIndahareshowinAppendix
2,FigureA2.9,A2.10,andA2.11,respectively.
22
Figure14:AnnualhomerangesizebasedontheminimumconvexpolygonforFeb(residentadult female)from2010to2017.(n=numberoffollows/year:2010:n=22;2011:n=22;2012:n=31;2013:n=50;2014:n=18;2015pre-fire:n=15;2016:n=14;2017:n=9)
4.Discussion
Borneanorangutansare increasinglyatriskfromforest fireseven inprotectedareassuchasSabangau,as
previous degradation reduced the region’s resilience, making it vulnerable to fires from the surrounding
developingarea(Cochrane,2003;Siegertetal.,2001;VanEijketal.,2009).Whilethereissubstantialresearch
ontheimpactsoffiresonecosystemstructure(ClearyandPriadjati,2005;CochraneandSchulze,1999;Sliket
al., 2010, 2008; Slik and Eichhorn, 2003), little focuses on the consequences for forest dwelling species.
Hitherto,therelationshipsbetweenfireinducedforestcoverchangesandorangutanpopulationdynamicshas
beenunclear.
Overall,IfoundthatSabangauforestcoverdeclinedby830.3km2frompre-fire2006topost-fire2015.
Despitetheforestcoverdecline,Sabangau’sorangutanpopulationisestimatedtohaveincreasedby3621to
8775 individuals over the same period. This increase in population is driven by a significant increase in
23
orangutandensityinMSF-P,MSF-I,andLPFwiththegreatestpopulationincreaseinLPFandTIF.Myprediction
that density would increase after a fire was supported most strongly when looking at MSF-T as density
increased significantly for 9outof 15 fire seasons; however, therewasmore variation in thedirectionof
changewhenexaminingMSF-PandMSF-Iseparately.Althoughfemalehomerangesizediddecreasepost-fire
aspredicted,thischangewasnotsignificant.
4.1Changeinforestcoverduetofire
Basedonthelandcoverclassification,MSF-PandMSF-Ihadthegreatestdeclineinforestcover,whileLPF’s
forestcover increasedslightlyoverthestudy.Landclearingactivitiesandtheirassociatedfires inthearea
surroundingSabangauandalongrivers’edgesmakeperipheralforestmorevulnerabletothespreadoffires
(Cochrane,2003).Thisexplains theconcentrationof firesanddegradation to the forestedge, causing the
higher loss in MSF-T compared to the other sub-habitats. As well, it appears that previously burnt and
degradedareasaremorevulnerabletofire,whichisconsistentwithpreviousresearch(Siegertetal.,2001;
VanEijketal.,2009)asnumerousburnscarswere inareaspreviouslyclassifiedasdegradedforest.Areas
adjacenttodegradedforestaremoresusceptibletofires(Lestarietal.,2016),whichIobservedasthefires
oftenexpandedoutfrompreviouslydegradedareas.
Aspoorimagequalitycausedsomepost-fireimagestobeselectedmonthsafterthefiresended,it’s
likelythatsomeburntareasexperiencedsomeregrowthorwereconvertedtosedgegrasses(VanEijketal.,
2009)leadingthemtobeclassifiedasdegradedorsedge.Combinedwiththefacethatfiresoftenoccurredin
degradedareas,burnscarareaitselfdoesnotnecessarilyrepresenttheextentofdamagetoprimaryforest
fromthatfireseason;thechangeinforestcoverisabettermetricforannualdamagefromfires.AsSabangau
isstillsubjecttoillegallogging(Tsujinoetal.,2016;Wichetal.,2012;Yule,2010),changeinforestcovermay
includelossesattributedtologging,butthis is likelysmallcomparedtotheareaaffectedbyfires(OuTrop,
2012). Comparing imagery that identifies fire hotspots, such as MODIS satellite product MOD14A2, to
24
classified Landsat images would help differentiate forest fire impacts from other types of degradation.
However,thetypeofdegradationdoesnotaltertheoutcomesofmyassessmentontheimpactstoorangutans
asit’sbasedonchangeinforestcovernottheintensityofforestdegradation.
4.2Orangutandensityandchangeinforestcoverduetofire
4.2.1Overallchangesindensityandforestcover
Average annual orangutan density increased inMSF-P,MSF-I, and TIF since 2002. Several factorsmay be
influencingthisincrease,oneofwhichisthedecreaseinforestcoverasseenbytherelationshipbetweenMSF
orangutandensityandforestcover.Thereductioninsuitablehabitatbyfiresmaycompressthepopulation
andincreasedensity(Marshalletal.,2008;Speharetal.,2010).However,forallMSFsub-habitats,forestcover
explainedalowamountofvariationinorangutandensityindicatingthatotherfactorsareinfluencingthelong-
termdensityincrease.
Thedensity increaseovertimemaybe linkedtothecessationof32yearsofselective loggingthat
occurredpriortoSabangau’snationalparkdesignationin2004(Morrogh-Bernardetal.,2011).Astheforest
structurerecovers,theecosystemisbetterabletosupportlargerorangutanpopulations(Morrogh-Bernard
etal.,2003)duetoimprovedhabitatqualityandfoodavailability(Ancrenazetal.,2010;Davies,1986)allowing
individualstorepopulatethearea(Knopetal.,2004).Slightdegradationinecosystemstructureandhabitat
quality in older regrowth cannot always be distinguished from primary peat swamp forest in land cover
classification(Wijedadaetal.,2012),sotherelationshipbetweenorangutandensityand improvedhabitat
qualityinoldregrowthisnotcontainedwithintherelationshipwithforestcoverchange.AlthoughIdidnot
measureforestcoverpriorto2006,Margonoetal.’s(2014)datashowsthatthetrendfordecreasingforest
coverextendsfrom2000to2015,astherewas255.8km2moreprimaryforest in2000thanpre-fire2006.
Thus,thedensityincreasefrom2002to2006mayalsobeinfluencedbythecorrespondingdeclineinforest
cover.
25
TheoscillationinMSFdensitymaybeinfluencedbyvariationinresourceavailability.Asorangutan
densityiscorrelatedwithfruitavailability(Carneetal.,2015;Hussonetal.,2008),thisoscillatingpatternmay
reflect annual variation in food resources and abiotic factors such as drought (Fredriksson et al., 2007;
Kanamorietal.,2017), leadingtovariationinbirthanddeathratesaswellasimmigrationandemigration.
Migrationismorelikelyresponsiblefortheobservedoscillationindensityaschangesinbirthratewilllagthe
triggering factors due to orangutans’ long inter-birth interval. Other population pressures such as illegal
huntingcouldalsoplayarole(Abrametal.,2015;Meijaardetal.,2012).
4.2.2Variationindensityandforestcoverchangesamongsub-habitats
Thespatialdistributionofforestfiresandorangutandensityofeachsub-habitatwillinfluencethelong-term
effectsoffiresonSabangau’sorangutanpopulation.FirespredominantlyoccurredinMSF-P,meaninghigh
orangutan density habitat was mainly affected. Although MSF-P’s population decreased over the study,
individualswerenotnecessarykilledbythefirebutmayhavemigratedtoothersub-habitatsinSabangau.The
overalldecreaseinforestcoverandincreaseinpopulationinMSF-ImaysuggestthatMSF-Ireceivedaninflux
ofdisplacedindividuals,likelyfromneighbouringMSF-P.Thismovementofindividualsmayalsoaccountfor
the increaseddensity post-fire inMSF-I, but not inMSF-P, such as in 2010 and2012. Similarly, the217%
increaseinLPF’spopulationmaybeinfluencedbymigrationofdisplacedindividuals.However,otherfactors
suchasseasonalityandvariationinresourceavailability(Kanamorietal.,2017;SingletonandvanSchaik,2001)
andmovementofrovingmaleswithlessstablehomeranges(Morrogh-Bernardetal.,2011;Spillmannetal.,
2017)cannotbeexcludedasfactorspossiblyinfluencingchangesindensity.
AlargelossofforestcoverfromMSFcoupledwithminimalburninginLPFresultedinasubstantial
decreaseintheproportionofSabangau’stotalforestcovercontainedinMSFswhilethisfactorincreasedin
LPF.The lowdensity inLPFthroughoutthestudysuggeststhatSabangau’sorangutanpopulationsizemay
becomelimitedifLPFcontinuestoincreasinglyrepresentSabangau’stotalforestcover.Thelowerorangutan
density in LPF compared to the other sub-habitats is due to low tree species diversity and lower canopy
heterogeneity(Pageetal.1997;Pageetal.,1999),makingitlessdiverseandapoorerhabitatfororangutans.
26
Assuch,itisnotthetotalforestlostbyfireinSabangauthatwillprimarilyinfluencetheorangutanpopulation,
butthespatialdistributionoffiresinthesub-habitatsasthiswillimpactthenumberofindividualsdisplaced,
thequalityoftheremaininghabitat,andtheoveralldensitythatSabangaucansupport.
4.2.3Displacementandchangeinorangutandensity
Whiledisplacementof individuals tounaffected areashasnot been studiedpost-fire, it’s known tooccur
adjacenttologgedsites(Davies,1986;Hussonetal.,2008;Russonetal.,2001)asloggingreducesorangutan
density(Feltonetal.,2003;Hussonetal.,2008;MejaardandWich,2014;ReijksenandMeijaard,1999;van
Schaik andRao, 1997). Since fires and logging cause similar changes in ecosystem structure and resource
availability(Sliketal.,2002),asimilarresponsebyorangutansafterfirecanreasonablybeexpected,which
mayaccountforchangesindensitypost-fire. InMSF-T,densityfrequentlyincreasedpost-fire,withgreater
variabilityinMSF-PandMSF-I.ThedensitydecreaseinMSF-Pafterfiresin2010and2012correspondedto
increases inMSF-I,whichmay indicatemigrationof individuals fromthe former to the latter.However, in
2005,2008,and2016densitydecreasedinbothsub-habitats.It’spossiblethatindividualsmigratedtoLPF,TIF
orVLC,but as therewasnomonthlydataprovided for these sub-habitats, the likelihoodof thisover the
influenceofotherenvironmentalfactorscannotbestated.
Asorangutansaregeneralist frugivores (Galdikas, 1988),decreaseddensity indisturbed regions is
linkedtoareductioninfruittrees(Rijksen&Meijaard,1999),astheirdensityispositivelycorrelatedwiththe
amountoffoodavailable(Hussonetal.,2008).However,orangutanshavebeendocumentedtoexhibithigh
dietaryflexibilityinmodifiedlandscapes(Campbell-Smithetal.,2011b)astheyareadaptedtoperiodsoflow
fruitavailability(vanSchaiketal.,2008)throughrelianceonfallbackfoods,suchasleaves,seeds,bark,and
invertebrates(Morrogh-Bernardetal.,2008;Russonetal.,2008;vanSchaikandRao,1997).Populationsthat
donotnaturallyexperiencesuchdramaticfluctuationsinfruitabundance,suchasthoseinnon-mastingpeat
swamp forests like Sabangau (Cannon et al., 2007),maybemorenegatively impactedby prolonged food
shortages(vanSchaiketal.,2008).Aswell,firewilllikelydegradethequalityandquantityofthosefallback
resources(Sliketal.,2002;LeightonandWirawan,1986;VanEijketal.,2009),unlikeselectiveloggingthat
27
preservessomeintacttreesfororangutanstofallbackon(Feltonetal.,2003).Consequently,aregionmaybe
unabletosupportitspreviousorangutanpopulationiffiresdestroysubstantialprimaryandfallbackfoods,
whichcouldcausethedisplacementofindividualsfromburnttounburntareaseitherwithinorbetweensub-
habitats.
Likelogging(Feltonetal.,2003;Marshalletal.,2006;vanSchaikandRao,1997),thescaleofhabitat
degradationanddensitydeclinepost-firewillvarywithfireintensityandthedamagetoorangutans’resources
(Blackhametal.,2014;Pageetal.,2009b;Russonetal.,2015;Sliketal.,2008),whichmayaccountforannual
variation inthedensitychangepost-fire.Asmentioned, firewilldestroyfallbackfoods,butthenumberof
resourceslostwillincreasewithfireintensity(Sliketal.,2010).Therefore,themoredamagingthefire,the
moredifficultitwillbefororangutanstomeettheirenergyintakerequirements(Knott,1998;Vogeletal.,
2012),possiblyforcingindividualsoutofthearea.In1982,anextremelystrongElNiñocontributedtohigh
intensityfiresinBorneothatkilledupto60%ofprimatefruittreesand90%oflargelianasandfigsinsome
dipterocarpforestsandseverelydamagedsurvivingvegetation(LeightonandWirawan,1986;Russonetal.,
2015).WhileecosystemdegradationhasnotbeenquantifiedforSabangau,theextensivedroughtandElNiño
eventin2006(Yuliantietal.2012)and2015(Tacconi,2016),respectively,likelycontributedtothehighforest
cover lossandpossiblysubstantiallyreducedfoodresources. Inbothyears,orangutandensitysignificantly
increasedpost-fireinallMSFsub-habitatsexceptforMSF-Iin2006wheretheincreasewasnotsignificant,
which may indicate that individuals were displaced. Examining changes in density and displacement of
individualspost-firecouldbeimprovedbyassessingfireintensityandquantifyingthedegreeofdamageto
theecosystem.
Ifthepopulationintheundisturbedhabitatisatornearcarryingcapacity,aninfluxofindividualsmay
lead to refugee crowding – an overshoot of the carrying capacity in a refuge habitatwhich neighbours a
degradedecosystem(MacKinnon,1971;RijksenandMeijaard,1999),whichincreasesdensityandhomerange
overlap(Carneetal.,2015)causingfoodshortages(Koenig,2002;RijksenandMeijaard,1999)andincreased
relianceonfallbackfoods(Carneetal.,2015).Orangutansaresensitivetochangesindensityandrangeoverlap
28
astheyalreadyliveclosetothelimitsoffoodresourceavailability(Carneetal.,2015).Although,aspreviously
mentioned,theyhavesomenaturaldietaryflexibilitythroughfallbackfoodstoshorttermfluctuationsinfood
resourcesandcarryingcapacity(Leightonetal.,1995),thedegreeoftolerancevariesamongpopulationswith
lessflexibilityamongthoseinforestssuchasSabangauwherefruitavailabilityismoretemporarilystable(van
Schaiketal.,2008).Aswell, compressionof thepopulation,even in theshort term,canhavedetrimental
effectson social cohesionand reproductive success (RijksenandMeijaard,1999).This isdue to increased
agonistic interactions and intraspecific contest competition (Knott et al., 2008), which in turn depresses
fecundityandincreasesmortality(Marshalletal.,2008).Theseimpactsofcrowdingtoorangutans’socialand
reproductive health will likely be exacerbated in lower quality habitat such as LPF that are increasingly
supportingagreaterproportionofthetotalpopulation.Sabangau’sorangutansdonotappeartohavereached
carryingcapacityastheirpopulationisstillincreasing,sotheyarenotlikelyexperiencingrefugeecrowdingat
thisscale.However,spatialvariationinhabitatqualityanddensitymaycauselocalizedimpactsfromrefugee
crowding,theeffectsofwhichwillnotimmediatelybecomeapparentinpopulationdataduetoorangutans’
longlifehistory(Marshalletal.,2008).
Asmentioned, therewillbevariation inorangutans’ responseto firesdependingonthedegreeof
degradation,sospatialvariationinchangestodensityinunburntforestwithineachsub-habitatisexpected
depending on fire intensity and proximity; however, this is not captured by the data as each sub-habitat
representsasingleregioninSabangau.Forthisreason,thechangesindensitymaynottrulyrepresentthe
impactsoffireswithineachsub-habitatandSabangauiffiresdidnotburncloseenoughtothesampledsite
for them to experience density changes as a result. Furthermore, Abram et al. (2015) found Sabangau’s
orangutanpopulationtobeindeclineinrecentyearsduetohumanconflictandkilling,however,thistrendis
notreflectedinourdataset.Thisdiscrepancymaybeduetotheuseofasinglesamplesiteforeachsub-habitat
thatdoesn’tcapturespatialvariationinpopulationpressuresandtheconsequentialchanges inpopulation
density throughout the sub-habitat. However, this analysis provides the best estimate based on the data
available.
29
4.3Orangutanhomerange
Although there is no significant variation in female home range size, the decreasing trend post-fire is as
expected.Thehigherorangutandensitypost-fire inMSF,whichwasmeasured inthesamelocationasthe
followdata,suggeststhatnewindividualsenteredthearea,possiblyfromthetwoadjacentburnsitesboth
lessthan1kmaway.Thisshiftisconsistentwiththeconceptofrefugeecrowdingpreviouslymentioned,as
potentialcrowdingfromrefugeesmaycompressindividuals’homeranges.Eventhoughfemaleshavehighly
stable home ranges (Singleton and van Schaik, 2001), there is some variation in the extent and spatial
orientation of their range (Isbell, 1991),making it reasonable that changes in density and environmental
factorswouldelicitshiftsinhomerange.
Whilethere isnoresearchavailableonthedynamicsoffemalerangesizeafteradisturbancewith
whichtocomparemyresults,femalebehaviourandrangeoverlaptendenciessuggeststhatcontractionisa
likely consequence of crowding. The degree of home range overlap varies depending on the relationship
betweenindividuals,withahigherdegreeofoverlapbetweenkincomparedtonon-kin(Knottetal.,2008;
Singleton and van Schaik, 2002). Although females scramble compete for resources with overlapping
individuals,theyavoidagonisticencountersbyactivelyavoidinginteractionwithotherorangutans(Knottet
al.,2008).Knotetal.(2008)foundthatmostunrelatedfemaledyadsavoideachotherwhenranginginthe
sameareaandencounteredeachothersignificantly less thanexpected.Activeavoidanceofmigrants that
overlaptheirrangemaycausefemalestocoverlessoftheirpreviousrangeleadingtorangesizecontraction.
Additionally,femalesadjusttheextentoftheirhomerangeoverlapbasedonthedensityofindividualsand
resources (Isbell, 1991),meaning the increased density post-fire 2015may have influenced the trend for
smallerhomeranges.Furthermore,comparedtootherpeatswampforestsinBorneo,femalesinSabangau
havesomeofthesmallesthomerangesandhomerangeoverlap(Morrogh-Bernard,2003;Singletonetal.,
2008). This is attributed to the homogeneity in Sabangau’s spatiotemporal pattern of food supply,which
allowsindividualstoacquirethenecessaryresourcesoverasmallerarea(Singletonetal.,2008).Asaresult,
newindividualsemigratingfromtheneighbouringburntforestcouldincreaseoverlaptoadegreeresidents
30
areunaccustomedto,thuscausingthemtocontracttheirranges.Overallthebehaviouroffemalessuggests
it’spossiblethataninfluxofnewindividualscouldreducethehomerangesizeofresidentfemales.Asthere
arenootherstudiestocomparewith,it’sunclearifthelackofsignificanceinfemaleresponsereflectstheir
truebehaviour,orisduetotheweakstatisticalpoweroftheanalysisduetothelowsamplesizeofthedata.
4.4Long-termeffects
DespitetheincreaseinorangutandensityandpopulationinSabangau,ifthepatternofannualfires(Hoscilo
etal.,2011;LangnerandSiegert,2009)anddecreasingforestcovercontinues(Gaveauetal.,2014;Hansenet
al.,2013;Tsujinoetal.,2016),thepopulationmaybecompressedtothepointofexceedingcarryingcapacity
leadingtoapossiblepopulationdecline(Marshalletal.,2008).AnnualfiresinIndonesiaandSabangauwill
likelycontinuetooccur,asthereisaninadequateregulatoryandlegalframeworkinthecountrytoaddress
fires (Nurhidayah, 2013), and legal efforts to reduce deforestation and its associated fires have not been
successful(Buschetal.,2015;Margonoetal.,2014).Aspeatswampforestsareslowtorecoverfromfires
(Chisholmetal.,2016;Pageetal.,2009b;Sliketal.,2008;Yule,2010)andfirestendtooccurinareasthat
werepreviouslyburnt(CochraneandSchulze,1999;Hosciloetal.,2011;Siegertetal.,2001),regeneration
and increased resilience to fires is limited (Page et al., 2009a; Van Eijk et al., 2009). This puts orangutan
populationsnearpreviouslyburntareasatriskforanannualinfluxofmigrantsandlossoftheirownhabitat
as these firespotentiallyexpand toprimary forest.Furthermore, the riskof increasingstrengthofElNiño
eventsduetoclimatechange(Caietal.,2014;Dai,2013)alsoincreasesthelikelihoodofseverefireevents
(Jollyetal.,2015),suchasthosein2006and2015.
Whilecrowdinghasnotyethadanegativeimpactonpopulationgrowth,overtimeovercrowdingand
resourcesharinginconditionsoffoodshortage,evenintheshortterm,canhaveimplicationsonindividuals’
health, survival, and fecundity (Knott, 1998; Knott, 2001; Rijsken & Meijaard, 1999; Vogel et al., 2012).
Decreasedfoodavailabilitycanseverelyreducefatstores,causingahormoneimbalancethatcompromises
31
conception(Knott,1998)andcanlengthentheinter-birthinterval(Knott,2001;Knottetal.,2008),whichif
lengthenedby2yearscancausenegativepopulationgrowth(Tildonetal.,1993).Orangutans’slowlifehistory
and long reproductive cyclemeans thedetriment to thepopulationmaynotbe immediatelyevident; the
populationmayestablishanextinctiondebt (sensuTilmanetal.,1994)and in timeexperiencepopulation
decline(Marshalletal.,2008).AsSabangaudoesnotappeartobeatcarryingcapacity,crowdingmaynot
currentlybehighenoughtosubstantiallyalterreproductivecyclesandsocialcohesion.However,ifdensity
andcrowdingcontinueto increaseandhomerangescontractduetoannualfires,thenegative impactson
populationstabilitycouldbecomerealized.
4.5Futureresearch
I’veshownthatorangutandensityinMSFsub-habitatsoftenvarypre-firetopost-fire,howeveracomplete
understandingoftheimplicationsforSabangau’sorangutanscannotbegaineduntiltheothersub-habitats
areassessedinasmuchdetail.ResearchthatgathersmorefrequentdensitydatafromLPF,TIF,andVLCto
analyze fire impacts would yield a clearer understanding of how Sabangau’s whole population is being
impactedbyfires,andmaygivefurtherinsightintothemovementofindividualsbetweensub-habitats.
There is no research on how variation in fire intensity impacts orangutans’ responses to the
disturbance.It’sevidentthatdegradedhabitatscansupportorangutanstosomedegree,butwithoutspecific
assessment on the damage to ecosystem structure by varying levels of fire intensity and the range of
consequencesontheresidentandneighbouringorangutans,thelossandmovementofindividualscannotbe
accurately estimated. This suggested research coupledwithmy assessment of the relationships between
change in forest cover and fire occurrence with orangutan density would yield a more comprehensive
understandingofthechangesintheorangutanpopulationandwhatthelong-termconsequencesmaybe.
Carryingonfrommyanalysisonchangesinhomerangesize,researchonrangeoverlapandrange
packingwouldbeuseful to furtherassess the impactsof fireonrangingbehaviour.However, thisanalysis
32
requiresdatatobecollectedonallindividualswithequaleffortandnosuchdataiscurrentlyavailable.Future
workwouldbenefitfromindividualsbeingfollowedinasystematicwaythatensuresrandomsamplingofthe
populationandmoreequalityamongtheage-sexclassesovertime.Moreequaleffortmayalsoincreasethe
samplesizeandstatisticalpower,asunder-sampledindividualsthatarecurrentlynon-residentsmaybetrue
residentsofthepopulation.
5.Conclusions
Overall,forestfiresdecreasedforestcoverinSabangauNationalParkfrom2006to2015.Whilethischangein
forestcoverhadsomeeffectonincreasingorangutandensityovertime,theinfluencewaslimited,implying
thereareadditionalcontributingbioticorabioticfactors.Despitethedecreaseinforestcover,theestimated
orangutanpopulationhasincreasedduetoincreaseddensity.Orangutandensityfrequentlyincreasedpost-
firesignifyingthathabitatdegradationmaytriggerthemigrationofindividualsfromburnttounburntrefuge
areas.Femalehomerangesizeinunburnthabitatisnotsignificantlyimpactedbyfire,howevertheincrease
indensitymaycausefemalestocontracttheirhomerangestoavoidinteractionwithunfamiliarindividuals,
as suggested by the tendency for small home ranges post-fire. These changes to orangutan density and
distributioncouldpotentiallyimpedeindividuals’accesstoresourcesleadingtocompromisedwellbeingand
fitness.
Currently Sabangau’s orangutan population is increasing despite fires decreasing forest cover.
However,thereisasriskthatcontinualforestdegradationbyfirewillincreasethepopulationdensitybeyond
carrying capacityand that someof these impactshavenot yetbeen realizeddue toorangutans’ slow life
history.Assuch,it’sessentialthateffortbemadetoreduceintentionallysetfiresintheareasurroundingand
withinSabangautoensurethattheorangutanpopulationcontinuestoincrease.
33
Acknowledgements
Iwouldliketothankmysupervisors,Dr.FrankvanVeenandDr.HelenMorrogh-Bernard,fortheirguidance
andfeedbackthroughoutthisprojectandSaraEshpeterandBernieRipollCapillafortheirinvaluableadvice
onmylandcoverclassificationmethods.Theorangutandensitydataandfollowdatausedtoevaluatehome
range were collected by the Borneo Nature foundation (BNF) team as part of the BNF/CIMTROP multi-
disciplinaryresearchprojectinthenorthernSabangauForest,CentralKalimantan,Indonesia.
34
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1.Estimatinghabitatlossduetofire
1.1Data
IusedimagesfromtheLandsatsatelliteseriestoclassifylandcoverbeforeandaftereachfireeventforthe
threeyearsofinterest,2006,2010,and2015.ImagesarefreelyavailablefromtheUnitedStatesGeological
Survey (USGS) Earth ResourcesObservation and Science (EROS) Data Centre via their Earth Explorerweb
interface(http://earthexplorer.usgs.gov/).TheanalysisusedimagesfromseveralLandsatsensors,including
ThematicMapper(TM),EnhancedThematicMapperPlus(ETM+),andOperationalLandImagerandThermal
InfraredSensor(OLI/TIRS),allofwhichhavearesolutionof30X30m.
Ilimitedthesearchforimagesforthepath/row:118/62tothosetakenduringthedaywithlessthan
30%cloudcover.IavoidedLandsat7imageswiththeScanLineCorrector(SLC)-offunlesstheimagesfromthe
othersatelliteswereinsufficient;thisoccurredforthe2006post-fireand2010post-fireimages(TableA1.1).
Foreachyear,Iexamined8-daycompositeimagesofactivefiresinSabangaufromtheModerateResolution
Imaging Spectroradiometer (MODIS) satellite product MOD14A2 acquired from Earthdata
(https://earthengine.google.com)todeterminethestartandendofeachfireseason.Basedonthisevaluation,
IonlyselectedLandsatimagesfromDecembertotheendofJuly,astherewerenofiresobservedduringthose
months,whichwassupportedbymonthlyfirehotspotanalysisdonebyYuliantietal.(2012).Whenpossible,
Ipreferentiallyselectedpre-fireimagesatthebeginningofthefireseason(i.e.July)andpost-fireimagesat
theend(i.e.December).However,poorimagequalityduetoheavycloudcoverlimitedthenumberofusable
images,causingsometobeselectedseveralmonthsbeforeorafterthefire.Duetoalackofusableimages,
the2015pre-fire image is fromAugust3rd,2015;however,as it is stilloutsideof thatyear’s fireseason, I
deemeditacceptable.Additionally, Iusedtwoimagestocompletetheclassificationfor2015post-fireand
2006pre-fireassubstantialareawascoveredbycloud.
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TableA1.1:Satelliteimagesusedforlandcoverclassification.
Category DateAcquired SatelliteSensor Spatial
Resolution(m)Bandsusedforclassification¶
ClassificationUse
2006Pre-Fire07-06-2006 Landsat5TM 30X30 2,3,4,5,7 Primary09-07-2006 Landsat5TM 30X30 2,3,4,5,7 Fillgaps
2006Post-Fire 04-07-2007‡ Landsat7ETM+ 30X30 2,3,4,5,7 Primary
2010Pre-Fire 10-02-2010 Landsat5TM 30X30 2,3,4,5,7 Primary
2010Post-Fire13-06-2011∫ Landsat7ETM+ 30X30 2,3,4,5,7 Primary12-05-2011¥ Landsat7ETM+ 30X30 2,3,4,5,7 Fillgaps
2015Pre-Fire 03-08-2015 Landsat8OLI/TIRS 30X30 3,4,5,6,7 Primary
2015Post-Fire 14-03-2016 Landsat8OLI/TIRS 30X30 3,4,5,6,7 Primary‡gapfilledwithLandsat7ETM+imagefrom05-08-2007usinglocalhistogrammatching∫gapfilledwithLandsat7ETM+imagefrom12-05-2011usinglocalhistogrammatching¥gapfilledwithLandsat7ETM+imagefrom13-06-2011usinglocalhistogrammatching¶Thecorrespondingspectralwavelengthforeachbandare:Landsat5TMandLandsat7ETM+:band2=green,band3=red,band4=nearinfrared,band5=shortwaveinfrared-1,band7=shortwaveinfrared-2;Landsat8OLI/TIRS:band3=green,band4=red,band4=nearinfrared,band6=shortwaveinfrared-1,band7=shortwaveinfrared-21.2Pre-processing
RadiometriccorrectionofLandsatimagesisrequiredwhenmappingchangesinhabitatandwhencomparing
multispectral images temporally (Lu andWeng, 2007) as itminimizes the effects of differences in sensor
calibration,sun-earthdistance,andsunelevation(Youngetal.,2017).Todothis,Iconvertedtherawdigital
values (DN) to top of atmosphere (TOA) reflectance (Hansen et al., 2008; Potapov et al., 2012) using the
radiometric calibration tool in ENVI 5.4. To reduce reflectance variation between images dates due to
atmosphericconditions,IusedENVI5.4todoadarkobjectsubtractionatmosphericcorrection(Chavez,1988).
TheLandsat7ETM+imageswithSLC-offneededtohavetheareaswithnodatacorrectedpriorto
classificationasabout25%ofthedatawasmissingfromtheimage(Triggetal.,2006;Wulderetal.,2008).I
didthisusinglocalhistogrammatchingthroughtheLandsatGapFillextensioninENVI5.4(Storeyetal.,2005),
whichusesdatafromasecondEMT+imagetakenatasimilartimetoestimatethevaluesofthemissingpixels.
AllimageswereprojectedtotheUniversalTransverseMercator(UTM)projection,Zone50Southin
ArcMap10.5,whichIusedfortheremainderoftheanalysis.Toremovecloudandshadow,Igeneratedcloud
masksfromeachimages’qualityassessment(QA)bandandappliedthemtothemultispectralimagesinorder
toimproveclassificationquality(Xieetal.,2008).IclippedtheimagestotheSabangaustudyareawithinthe
Appendix1:SupplementaryMethods
45
boundaryoftheSabangauandKatinganRivers.Toexcludethedevelopmentalongtheperipheryoftheforest,
Idelimitedthestudyareabasedonprimaryforestdatafrom2000(Margonoetal.,2014)retrievedfromGlobal
Forest Watch (http://www.globalforestwatch.org). As orangutans do not occupy sedge grass (Morrogh-
Bernard,pers.comm.),Iremovedthesedgepatchesborderingtheriversasthissimplifiedtheclassification.
1.3Landcoverclassification
Iusedamaximumlikelihoodsupervisedclassification(MLC)approachtoclassifythe images intonine land
coverclasses(TableA1.2),asMLCisacommonandaccuratemethodforclassifyingforests(Jiaetal.,2014;Li
etal.,2014;LuandWeng,2007;RawatandKumar,2015).Ibasedthelandcoverclassesonpreviousstudies
ofpeatswampforest (Hosciloetal.,2011;Wijedadaetal.,2012),visualstudyofthesatellite images,and
communicationabouttheecosystemwithDr.Morrogh-BernardofBNF.
TableA1.2:Descriptionoflandcoverclassesusedfortheclassification.Category LandCoverClass Description
Forest Peatswampforest(PSF)
Undisturbedpeatswampforest,oldre-growthwithminimaldisturbancefromfireorlogging;includessomeoldsecondaryforestthatwaspreviouslyloggedandcannotbedistinguishedfromundisturbedpeatswamp
Non-Forest
Burnscar Recentlyburnedarea;bareearthwithlittletonovegetation.
Degradedforest
Peatswampforestthathasbeendegradedbyloggingand/orfire.Includesareasofopencanopypeatswampandareasofrecent,minimalvegetationre-growththatexhibitsdistinguishabletextureandreflectancefromprimaryandoldre-growthpeatswampforest.
SedgeAreasofnon-woodyvegetationandtheriversandfloodedpeatcontainedwithinthem.
Water Riversandlakesincludingseasonallyfloodedareas.
NoData
Cloud Cloudthatwasnotremovedbythecloudmask.
Haze Thin,wispycloudthatwasnotremovedbythecloudmask.
CloudShadow Cloudshadowthatwasnotremovedbythecloudmask.
Null SLC-offareasthatwerenotproperlyfilledbythelocalhistogrammatchingmethod.
Idigitizedtrainingpolygonsbasedonvisualanalysis infalsecolour(shortwaveinfrared-1(SWIR-1),
nearinfrared(NIR),andred)foreachimageseparately.Theareaoftrainingpolygonsandnumberofpixels
usedvariedbyyeardependingonthecoverageofeachclassandthesimilarityinpixelvaluesbetweenclasses
Appendix1:SupplementaryMethods
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(TableA1.3).Toreducethe impactofatmosphericdisturbancesontheclassification (LangnerandSiegert,
2009),Iusedaspectralsubsetofbandsthatincludedbands2,3,4,5,and7forLandsat5and7imagesand
bands3,4,5,6,and7forLandsat8images.Thissubsetcoversthegreentoshortwaveinfraredspectrum,
whichcontainsthemostrelevantinformationfordetectingburnscarsandvegetation(LangnerandSiegert,
2009).Irepeatedtheprocessofcreatingtrainingpolygonsandrunningtheclassificationuntil,basedonvisual
inspectionoftheclassifiedimage,therewasahighlevelofaccuracyintheclassification.
TableA1.3:NumberofpolygonsandpixelsineachlandcoverclassusedfortrainingtheMLC.
¶Coveredanareaof4180km2asitwasusedtofillgapsduetocloudcover.‡Coveredanareaof919km2asitwasusedtofillgapsduetocloudcover.
Beforeclassifyingtheimagesusedtofilldatagapsfromcloudcoverin2006pre-fireand2010post-
fire,Iclippedtheimagestothecorrespondedareaintheprimaryimagethatrequiredfilling.Ithenclipped
thisareaoutoftheprimaryimage,classifiedthemindependently,andmergedthempost-classification.
1.4Post-processing
Per-pixel classification methods such as MLC can cause a ‘salt and pepper’ effect from isolated pixel
classification errors and requires post-classification processing to reduce the noise (Lu andWeng, 2007;
ImageDate No.of: Burnscar DegradedForest
Peatswampforest
Sedge Water Cloud Haze CloudShadow Null
07-06-2006Polygons 135 125 94 29 3 40 N/A 22 N/APixels 13524 31534 40959 1442 354 597 N/A 1517 N/A
09-07-2006¶Polygons 140 141 94 47 N/A 39 N/A 21 N/APixels 7220 13557 5280 2460 N/A 1001 N/A 887 N/A
04-07-2007Polygons 312 163 93 57 5 24 N/A 18 34Pixels 22496 10525 32026 1108 507 568 N/A 482 3706
10-02-2010Polygons 148 93 54 41 4 4 N/A N/A N/APixels 22598 22933 246851 3455 669 138 N/A N/A N/A
13-06-2011Polygons 266 214 88 48 4 40 N/A 22 38Pixels 15838 9434 33274 1184 510 1382 N/A 1022 4148
12-05-2011‡Polygons 100 102 23 16 N/A 9 N/A 12 10Pixels 1769 4064 4737 383 N/A 222 N/A 337 1072
03-08-2015Polygons 316 284 85 8 19 19 11 19 N/APixels 10889 12666 34805 105 708 222 471 342 N/A
14-03-2016Polygons 659 477 74 184 5 79 N/A 41 N/APixels 23782 12302 97733 3294 720 3437 N/A 1226 N/A
Appendix1:SupplementaryMethods
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Wijedadaetal.,2012)andimprovethequalityoftheclassification(Stefanovetal.,2001;LuandWeng,2004).
IcarriedthisoutusingArcMap10.5’smajorityfilter,boundaryclean,andnibbletools.
Furtherpost-processingwasdoneto identify the landclassesmaskedbyareasof ‘nodata’,which
includedcloud,cloudshadow,haze,andnullclasses.Inareaswithextensivehomogeneityandsmallnodata
clusters,examiningtheoriginalsatelliteimagewassufficienttodeterminethecorrectlandcoverclass.For
moreheterogeneousareasandthosewithdensernodataclusters,IusedtheNIRspectralbandtodistinguish
burn scars and healthy and degraded vegetation from each other, asNIR can penetrate thin cloud cover
(Marshaketal.,2000)andhasthehighestpowertodiscriminatebetweenburnedandunburnedareas(Pleniou
andKoutsias,2013;Schepersetal.,2014).Additionally,Iusedsecondaryimagesforthosethathadthemto
identifythecorrectclass.
To evaluate land cover changeswithin each sub-habitat, I used Ehlmer Smith and Ehlmer Smith’s
(2013)classificationandshapefileswhichdivideSabanagauinfoursub-habitats–mixed-swampforest(MSF),
low-poleforest(LPF),tall-interiorforest(TIF)andvery-lowcanopy(VLC)(FigureA1.1).IfurtherdividedMSF
(referredtoasMSF-total[MSF-T])intoMSF-interior(MSF-I)andMSF-perimeter(MSF-P)tocoincidewiththe
orangutandensitydata.MSF-Pextends2kmintotheforestfromtheedgeofriversandtheforestborder,and
MSF-I constitutes the remaining interior area. Lastly, I clipped the classified images to the sub-habitat
shapefilesthensummedtheareaofeachlandcoverclassineachsub-habitat.
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FigureA1.1:Sub-habitatswithintheSabangaustudyarea.Theblackstarrepresentsthe9km2researchplot.
AsSabangau isaprotectedarea, Iassumedthatallobservedchanges in forestcoverweredue to
forestfire,however,IacknowledgethatillegalloggingmayoccurinSabangau(Tsujinoetal.,2016;Wichet
al.,2012;Yule,2010).Iftheloggingwasextensiveenough,itmaybeclassifiedasdegradedforestbytheMLC,
but as illegal activityhas slowed in Sabangau (OuTrop,2012), itwould likelybe small relative to thearea
damagedbyfire.
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2.OrangutandensityTable A1.4: Annual orangutan density for each sub-habitat in Sabangau. Values forMSF-P andMSF-I areaveragesofmonthlyfieldobservations.ValuesforLPFandTIFareeithersingleannualfieldobservationsorestimatesbasedontheratiosLPF:MSF-IandTIF:MSF-P.Year MSF-P MSF-I LPF TIF2002 1.06 0.51 0.72 1.732003 0.99 0.62 0.81 1.56‡2004 1.26 0.88 0.55 1.642005 1.40 0.96 0.40 1.592006 1.34 0.80 0.51∫ 2.052007 1.51 0.76 0.48∫ 2.37‡2008 1.45 0.80 0.32 1.992009 1.30 0.71 0.46∫ 2.822010 1.51 0.76 0.48∫ 2.36‡2011 1.42 0.93 0.25 2.632012 1.70 1.13 0.72∫ 2.67‡2013 1.73 1.32 0.41 2.672014 1.91 1.29 0.83∫ 2.99‡2015 1.84 1.38 0.88∫ 2.89‡2016 2.12 1.81 1.25 3.32‡2017 2.11 1.78 1.14∫ 3.30‡
∫EstimateddensitybasedontheaverageoftheratioLPF:MSF-I‡EstimateddensitybasedontheaverageoftheratioTIF:MSF-P
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3.Orangutanhomerange
TableA1.5:Kjscoresforadultandadolescentfemalesobservedinthe9km2researchplotfrom2003to2017.Adultfemales(AF)aresexuallyactive,whileadolescentfemales(ADF)arenon-sexuallyactive.IndividualswithastatusofFrequentandRegularareresidentsofthepopulation.Kjscoresfor2015arecalculatedfortheyearaswellaspre-fire,during-fire,andpost-fire.Year Name Age-SexClass Kj Status¶
2003
Cleopatra AF 50 Frequent(resident)Feb ADF 100 Frequent(resident)Indah AF 50 Frequent(resident)Chopin ADF 25 Regular(resident)
No.ResidentsAF 2
ADF 2
2004
Cleopatra AF 50.0 Frequent(resident)Feb ADF 83.3 Frequent(resident)Indah AF 75.0 Frequent(resident)Teresia AF 25.0 Regular(resident)Potret AF 8.3 OccasionalViola AF 8.3 Occasional
No.Residents AF 3
ADF 1
2005
Cleopatra AF 58.3 Frequent(resident)Feb ADF 100.0 Frequent(resident)Indah AF 58.3 Frequent(resident)Viola AF 50.0 Frequent(resident)Indy ADF 25.0 Regular(resident)Gracia AF 8.3 OccasionalPotret AF 8.3 OccasionalTeresia AF 8.3 OccasionalWillow AF 8.3 Occasional
No.Residents AF 3
ADF 2
2006
Feb ADF 50.0 Frequent(resident)Indah AF 75.0 Frequent(resident)Indy ADF 33.3 Regular(resident)Cleopatra AF 16.7 OccasionalLeony AF 8.3 OccasionalNLF030206 AF 8.3 OccasionalViola AF 8.3 OccasionalWillow AF 8.3 Occasional
No.Residents AF 1
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ADF 2
2007
Feb ADF 75.0 Frequent(resident)Cleopatra AF 25.0 Regular(resident)Indah AF 41.7 Regular(resident)Indy ADF 41.7 Regular(resident)
No.Residents AF 2
ADF 2
2008
Indy ADF 58.3 Frequent(resident)Cleopatra AF 33.3 Regular(resident)Feb ADF 33.3 Regular(resident)Indah AF 33.3 Regular(resident)Teresia AF 25.0 Regular(resident)Viola AF 33.3 Regular(resident)Potret AF 8.3 OccasionalWillow AF 16.7 Occasional
No.Residents AF 4
ADF 2
2009
Indy ADF 58.3 Frequent(resident)Feb ADF 33.3 Regular(resident)Indah AF 41.7 Regular(resident)Aya AF 8.3 OccasionalBarita AF 8.3 OccasionalCleopatra AF 16.7 OccasionalEosah AF 8.3 OccasionalFossey AF 8.3 OccasionalSAF130909 ADF 8.3 OccasionalTeresia AF 8.3 OccasionalViola AF 8.3 OccasionalWillow AF 8.3 Occasional
No.Residents AF 1
ADF 2
2010
Feb AF 33.3 Regular(resident)Indy ADF 25.0 Regular(resident)Barita AF 8.3 OccasionalGracia AF 8.3 OccasionalTeresia AF 8.3 Occasional
No.Residents AF 1
ADF 1
2011 Indy ADF 50.0 Frequent(resident)Feb AF 41.7 Regular(resident)
Appendix1:SupplementaryMethods
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Teresia AF 25.0 Regular(resident)Barita AF 8.3 OccasionalCleopatra AF 8.3 OccasionalIndah AF 16.7 OccasionalViola AF 8.3 Occasional
No.Residents AF 2
ADF 1
2012
Feb AF 75.0 Frequent(resident)Indy AF 58.3 Frequent(resident)Gracia AF 25.0 Regular(resident)Indah AF 41.7 Regular(resident)Teresia AF 33.3 Regular(resident)Viola AF 25.0 Regular(resident)Barita AF 8.3 OccasionalCleo3 AF 8.3 OccasionalSAF041112 ADF 8.3 OccasionalU16_Fem_Adult AF 8.3 Occasional
No.Residents AF 6
ADF 0
2013
Feb AF 66.7 Frequent(resident)Indy AF 83.3 Frequent(resident)Teresia AF 75.0 Frequent(resident)Gracia AF 33.3 Regular(resident)Cleopatra AF 16.7 OccasionalGeorgia ADF 16.7 OccasionalIndah AF 8.3 OccasionalSAF110913 ADF 8.3 OccasionalTimi ADF 16.7 OccasionalWillow AF 8.3 OccasionalYana AF 8.3 Occasional
No.Residents AF 4
ADF 0
2014
Indy AF 83.3 Frequent(resident)Feb AF 41.7 Regular(resident)Georgia ADF 25.0 Regular(resident)Gracia AF 33.3 Regular(resident)Indah AF 33.3 Regular(resident)Teresia AF 41.7 Regular(resident)Timi ADF 33.3 Regular(resident)Cleopatra AF 16.7 Occasional
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Isabella ADF 16.7 OccasionalLipstik AF 8.3 Occasional
No.Residents AF 5
ADF 2
2015
Feb AF 58.3 Frequent(resident)Georgia ADF 33.3 Regular(resident)Gracia AF 33.3 Regular(resident)Indah AF 25.0 Regular(resident)Indy AF 41.7 Regular(resident)Isabella ADF 25.0 Regular(resident)Teresia AF 25.0 Regular(resident)Timi ADF 25.0 Regular(resident)
No.Residents AF 5
ADF 3
2015Pre-Fire
Feb AF 41.7 Regular(resident)Georgia ADF 25.0 Regular(resident)Indy AF 33.3 Regular(resident)Timi ADF 25.0 Regular(resident)Gracia AF 8.3 OccasionalIndah AF 16.7 OccasionalIsabella ADF 8.3 OccasionalTeresia AF 16.7 Occasional
No.Residents AF 2
ADF 2
2015During-Fire
Feb AF 8.3 OccasionalGeorgia ADF 8.3 OccasionalGracia AF 16.7 OccasionalIndah AF 8.3 OccasionalIndy AF 8.3 OccasionalIsabella ADF 16.7 OccasionalTeresia AF 8.3 Occasional
No.Residents AF 0
ADF 0
2015Post-Fire
Feb AF 8.3 OccasionalGracia ADF 8.3 Occasional
No.Residents AF 0
ADF 0
2016
Feb AF 41.7 Regular(resident)Georgia ADF 25.0 Regular(resident)Gracia AF 33.3 Regular(resident)Gretel ADF 33.3 Regular(resident)
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Indah AF 33.3 Regular(resident)Indy AF 41.7 Regular(resident)Juno AF 16.7 OccasionalTeresia AF 16.7 OccasionalTimi ADF 16.7 Occasional
No.Residents AF 4
ADF 2
2017*
Feb AF 60.0 Frequent(resident)Georgia ADF 60.0 Frequent(resident)Gretel ADF 40.0 Regular(resident)Juno AF 20.0 OccasionalTimi ADF 20.0 Occasional
No.Residents AF 1
ADF 2
*Kjisbasedona5-monthstudyperiod.¶Frequent:Kj≥50%;Regular:25%≤Kj<50%;Occasional:4%≤Kj<25%;Rare:Kj≤4%
Appendix1:SupplementaryMethods
55
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performance.Int.J.RemoteSens.28,823–870.doi:10.1080/01431160600746456Margono, B.A., Potapov, P. V, Turubanova, S., Stolle, F., Hansen,M.C., 2014. Primary forest cover loss in
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Potapov,P.V,Turubanova,S.A.,Hansen,M.C.,Adusei,B.,Broich,M.,Altstatt,A.,Mane,L.,Justice,C.O.,2012.
QuantifyingforestcoverlossinDemocraticRepublicoftheCongo,2000–2010,withLandsatETM+data.RemoteSens.Environ.122,106–116.doi:http://dx.doi.org/10.1016/j.rse.2011.08.027
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detection and burn severity assessment of a heathland fire in Belgium using airborne imagingspectroscopy(APEX).Rem.Sens.6,1803-1826.doi:https://doi.org/10.3390/rs6031803
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Fredriksson, G.M., Goossens, B., Husson, S.J., Lackman, I., Marshall, A.J., Naomi, A., Molidena, E.,Nardiyono,Nurcahyo,A.,Odom,K.,Panda,A.,Purnomo,Rafiastanto,A.,Ratnasari,D.,Santana,A.H.,Sapari,I.,vanSchaik,C.P.,Sihite,J.,Spehar,S.,Santoso,E.,Suyoko,A.,Tiju,A.,Usher,G.,Atmoko,S.S.U.,Willems, E.P., Meijaard, E., 2012. Understanding the Impacts of Land-Use Policies on a ThreatenedSpecies:IsThereaFuturefortheBorneanOrang-utan?PLoSOne7,e49142.
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for mapping of peat swamp forests in Sundaland. Rem. Sens. 4, 2595-2618. doi:https://doi.org/10.3390/rs4092595
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1.ChangeinforestcoverduetofireTableA2.1:Thearea(km2)ofeachlandcoverclassandthepercentchangeineachduetothe2006,2010,and2015firesinSabangau.ValuesarebasedonthelandcoverclassificationusingtheMLC
2006 2010 2015 Overall
Pre-fire Post-fire %Change Pre-fire Post-fire %Change Pre-fire Post-fire %Change %Change
PSF 5623.3 5061.1 -10.0 5313.8 5036.5 -5.2 5303.3 4793.0 -9.6 -14.7
Burnscar 234.7 897.4 282.4 518.1 700.4 35.2 422.7 843.9 99.7 259.6
Degraded 1071.6 1023.7 -4.5 1058.0 1249.4 18.1 1263.8 1343.4 6.3 25
Sedge 62.4 9.9 -84.2 95.0 5.3 -94.4 0.1 11.2 20769.0 -82.0
Water 3.8 3.7 -2.7 4.6 4.3 -5.7 5.9 3.7 -37.4 -1.7
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TableA2.2:Thearea(km2)ofeach landcoverclassandthepercentchange ineachduetothe2006,2010,and2015firesforthesub-habitatsofSabangau.ValuesarebasedonlandcoverclassificationbytheMLC. 2006 2010 2015 Overall Pre-fire Post-fire %Change Pre-fire Post-fire %Change Pre-fire Post-fire %Change %ChangeMSF-P PSF 874.9 622.0 -28.9 672.0 582.3 -13.3 618.8 482.5 -22.0 -44.9 Burnscar 115.3 485.5 321.0 325.3 448.2 37.8 271.9 388.5 42.9 236.9 Degraded 569.3 503.2 -11.6 533.9 583.9 9.4 727.4 737.9 1.4 29.6 Sedge 60.7 9.7 -84.0 88.0 5.1 -94.2 0.0 10.9 23773.8 -82.1 River 3.8 3.7 -2.7 4.6 4.3 -5.7 5.9 3.7 -37.4 -1.7MSF-I PSF 1689.5 1441.3 -14.7 1538.2 1424.2 -7.4 1542.0 1314.2 -14.8 -22.2 Burnscar 83.7 335.2 300.7 151.0 149.2 -1.2 119.7 323.4 170.1 286.6 Degraded 362.5 360.6 -0.5 437.7 563.9 28.8 475.6 499.6 5.1 37.8 Sedge 1.5 0.1 -94.2 5.1 0.0 -99.4 0.0 0.0 -69.2 -99.8 River 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0LPF PSF 1770.7 1739.4 -1.8 1830.8 1779.5 -2.8 1859.1 1776.7 -4.4 0.3 Burnscar 26.0 57.2 119.7 28.1 72.4 157.5 10.5 55.5 430.2 113.3 Degraded 110.2 110.4 0.2 46.3 55.1 18.9 37.4 74.4 98.9 -32.5 Sedge 0.0 0.0 0.0 0.7 0.0 -99.0 0.0 0.3 0.0 0.0 River 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0TIF PSF 1009.3 986.6 -2.3 1001.0 978.3 -2.3 1012.5 949.4 -6.2 -5.9 Burnscar 8.4 11.0 30.5 6.1 23.5 286.4 16.4 74.4 354.5 781.7 Degraded 26.7 46.9 75.6 36.6 42.6 16.7 15.7 20.8 32.2 -22.1 Sedge 0.1 0.1 -15.3 0.9 0.0 -96.0 0.0 0.0 0.0 -93.7 River 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0VLC PSF 278.8 271.8 -2.5 271.7 272.1 0.1 271.1 270.1 -0.3 -3.1 Burnscar 1.3 8.5 568.9 7.6 7.1 -6.1 4.3 2.1 -50.3 65.4 Degraded 3.0 2.7 -9.5 3.6 3.8 7.1 7.7 10.7 39.6 262.2 Sedge 0.0 0.0 0.0 0.2 0.1 -72.5 0.0 0.0 0.0 0.0 River 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
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2.Orangutandensity
a)
b)
FigureA2.1:Residualorangutandensityfora)MSF-Pandb)MSF-IfromJanuary2002toMay2017(n=131).
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3.Changeinorangutandensityandforestcover
FigureA2.2:Estimatedorangutanpopulationineachsub-habitatandintotalforpre-andpost-fire2006,2010,and2015.PopulationisestimatedfromthemeasuredandestimatedorangutandensityandtheareaofpeatswampforestasdeterminedbytheMLC.ThetotalvalueexcludesindividualsthatmayoccupyVLCasnodensitymeasurementsweretakenforthatsub-habitat.TableA2.3:Estimatedorangutanpopulationandpercentchangeineachsub-habitatandintotalforpre-andpost-fire2006,2010,and2015.PopulationisestimatedfromthemeasuredandestimatedorangutandensityandtheareaofpeatswampforestasdeterminedbytheMLC.
2006 2010 2015 Overall Pre-fire Post-fire %Change Pre-fire Post-fire %Change Pre-fire Post-fire %Change %Change
MSF-P 1224 940 -23.2 877 825 -5.9 1180 1021 -13.5 -16.6MSF-I 1623 1089 -32.9 1095 1331 21.5 1995 2382 19.4 46.8LPF 701 840 19.7 833 447 -46.4 1537 2221 44.5 216.7TIF 1605 2338 45.6 2827 2569 -9.1 3029 3151 4.0 96.3Total* 5154 5206 1.0 5632 5171 -8.2 7742 8775 13.3 70.3
*ExcludesindividualsthatmayoccupyVLCasnodensitymeasurementweretaken.
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FigureA2.3:PercentchangeintheproportionofSabangau’stotalforestcoverandpopulationrepresentedwithineachsub-habitatfrompre-fire2006topost-fire2015.
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There is a significant decreasing linear relationship between average orangutan density and
Sabangau’stotalforestcover inMSF-P(R2=0.330,F(1,74)=36.384,p<0.001)andMSF-I(R2=0.242,F(1,74)=
23.572,p<0.001)(FigureA2.4);however,inboththeamountofvariationindensityexplainedbythemodel
islow.
a)
b)
FigureA2.4:RelationshipbetweenSabangau’stotalforestcoverandaverageorangutandensityina)MSF-Pand b) MSF-I for pre- and post-fire 2006, 2010, and 2015. Forest cover values are based on land coverclassification by the MLC, and error bars represent 95% confidence intervals. The relationship betweenaverageorangutandensityandSabangau’stotalforestcoverisnotsignificantforMSF-P(p<0.001)orMSF-I(p<0.001).(n=6for5061km2and5623km2;n=5forallothers)
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TableA2.4:Summaryofpairedt-testresultsforvariationinaverageMSF-Torangutandensitybetweenpre-andpost-fireperiodsfor2002to2016.
Year Period N Mean SD T-value DF P-valueDirectionofchange
2002Pre-fire 5 0.71 0.04
-3.062 4 0.038* IncreasePost-fire 5 0.85 0.07
2003Pre-fire 6 0.84 0.07
-2.752 5 0.040* DecreasePost-fire 6 0.99 0.07
2004Pre-fire 6 0.99 0.07
-8.044 5 0.000* IncreasePost-fire 6 1.17 0.04
2005Pre-fire 6 1.17 0.04
4.124 5 0.009* DecreasePost-fire 6 1.05 0.05
2006Pre-fire 6 1.05 0.05
-5.731 5 0.002* IncreasePost-fire 6 1.14 0.04
2007Pre-fire 5 1.13 0.04
-3.428 4 0.027* IncreasePost-fire 5 1.21 0.03
2008Pre-fire 5 1.21 0.03
10.959 4 0.000* DecreasePost-fire 5 1.01 0.03
2009Pre-fire 5 1.01 0.03
-4.824 4 0.008* IncreasePost-fire 5 1.16 0.04
2010Pre-fire 5 1.16 0.04
-0.183 4 0.863 NochangePost-fire 5 1.16 0.05
2011Pre-fire 6 1.16 0.04
-10.119 5 0.000* IncreasePost-fire 6 1.43 0.08
2012Pre-fire 6 1.43 0.08
-2.980 5 0.031* IncreasePost-fire 6 1.55 0.02
2013Pre-fire 5 1.55 0.02
-0.575 4 0.596 IncreasePost-fire 5 1.57 0.06
2014Pre-fire 5 1.57 0.06
-1.422 4 0.228 IncreasePost-fire 5 1.67 0.10
2015Pre-fire 5 1.67 0.10
-4.522 4 0.011* IncreasePost-fire 5 1.90 0.02
2016Pre-fire 4 1.90 0.02
0.833 3 0.466 DecreasePost-fire 4 1.90 0.04
*Significantvariationbetweenmeanpre-fireandpost-fireorangutandensity
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The paired t-test on orangutan density grouped in 8-month pre- and post-fire periods showed
significantvariationbeforeandafter7fireeventsinMSF-P:2004(t(5)=-8.088,p<0.001),2006(t(5)=-3.909,p
=0.011),2008(t(4)=9.974,p=0.001),2009(t(4)=-5.403,p=0.006),2010(t(4)=3.046,p=0.038),2011(t(4)=-
6.235,p=0.002),and2015(t(5)=-3.040,p=0.038)(FigureA2.5;TableA2.4).Oftheseevents,densitywas
higherpost-fireinallbut2008and2010.
FigureA2.5:Averagepre-andpost-fireorangutandensityinMSF-Pfrom2002to2016.Errorbarsrepresent95%confidenceintervals.Significantdifferencesareindicatedby*p<0.05;**p<0.01;***p<0.001.(n=4in2016;n=5in2002,2007,2008,2009,2010,2013,2014,and2015;n=6in2003,2004,2005,2006,2011,and2012).
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TableA2.5:Summaryofpairedt-testresultsforvariationinaverageMSF-Porangutandensitybetweenpre-andpost-fireperiodsfor2002to2016.
Year Period N Mean SD T-value DF P-valueDirectionofChange
2002Pre-fire 5 0.95 0.07
-0.905 4 0.417 IncreasePost-fire 5 1.03 0.13
2003Pre-fire 6 0.99 0.15
-1.952 5 0.108 IncreasePost-fire 6 1.16 0.07
2004Pre-fire 6 1.16 0.07
-8.088 5 0.000* IncreasePost-fire 6 1.37 0.02
2005Pre-fire 6 1.37 0.02
1.872 5 0.120 DecreasePost-fire 6 1.31 0.07
2006Pre-fire 6 1.31 0.07
-3.909 5 0.011* IncreasePost-fire 6 1.47 0.05
2007Pre-fire 5 1.45 0.04
-2.620 4 0.059 IncreasePost-fire 5 1.52 0.03
2008Pre-fire 5 1.52 0.03
9.974 4 0.001* DecreasePost-fire 5 1.27 0.05
2009Pre-fire 5 1.27 0.05
-5.403 4 0.006* IncreasePost-fire 5 1.52 0.05
2010Pre-fire 5 1.52 0.05
3.046 4 0.038* DecreasePost-fire 5 1.42 0.02
2011Pre-fire 6 1.41 0.04
-6.235 5 0.002* IncreasePost-fire 6 1.74 0.13
2012Pre-fire 6 1.74 0.13
0.131 5 0.901 DecreasePost-fire 6 1.73 0.04
2013Pre-fire 5 1.74 0.04
-2.466 4 0.069 IncreasePost-fire 5 1.84 0.07
2014Pre-fire 5 1.84 0.07
-0.864 4 0.436 IncreasePost-fire 5 1.92 0.15
2015Pre-fire 5 1.92 0.15
-3.040 4 0.038* IncreasePost-fire 5 2.12 0.02
2016Pre-fire 4 2.11 0.02
1.007 3 0.388 DecreasePost-fire 4 2.07 0.09
*Significantvariationbetweenmeanpre-fireandpost-fireorangutandensity
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The paired t-test on orangutan density grouped in 8-month pre- and post-fire periods showed
significantvariationbeforeandafter9fireeventsinMSF-I:2002(t(4)=-9.459,p=0.001),2003(t(5)=-4.437,p
=0.007),2004(t(5)=-6.503,p=0.001),2005(t(5)=5.810,p=0.002),2008(t(4)=8.297,p=0.001),2010(t(4)=-
3.257,p=0.031),2011(t(4)=-5.645,p=0.002),2012(t(5)=-10.596,p<0.001),and2015(t(5)=-7.372,p=0.002)
(FigureA2.6;TableA2.5).Oftheseevents,densitywashigherpost-fireinallbut2005and2008.
FigureA2.6:Averagepre-andpost-fireorangutandensityinMSF-Ifrom2002to2016.Errorbarsrepresent95%confidenceintervals.Significantdifferencesareindicatedby*p<0.05;**p<0.01;***p<0.001.(n=4in2016;n=5in2002,2007,2008,2009,2010,2013,2014,and2015;n=6in2003,2004,2005,2006,2011,and2012).
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TableA2.6:Summaryofpairedt-testresultsforvariationinaverageMSF-Iorangutandensitybetweenpre-andpost-fireperiodsfor2002to2016.
Year Period N Mean SD T-value DF P-valueDirectionofChange
2002Pre-fire 5 0.43 0.03
-9.459 4 0.001* IncreasePost-fire 5 0.640 0.04
2003Pre-fire 6 0.66 0.06
-4.437 5 0.007* IncreasePost-fire 6 0.80 0.08
2004Pre-fire 6 0.80 0.08
-6.503 5 0.001* IncreasePost-fire 6 0.94 0.08
2005Pre-fire 6 0.94 0.08
5.810 5 0.002* DecreasePost-fire 6 0.74 0.03
2006Pre-fire 6 0.74 0.03
-0.877 5 0.421 IncreasePost-fire 6 0.76 0.06
2007Pre-fire 5 0.76 0.07
-2.025 4 0.113 IncreasePost-fire 5 0.84 0.03
2008Pre-fire 5 0.84 0.03
8.297 4 0.001* DecreasePost-fire 5 0.71 0.02
2009Pre-fire 5 0.71 0.02
-2.225 4 0.090 IncreasePost-fire 5 0.74 0.03
2010Pre-fire 5 0.74 0.03
-3.257 4 0.031* IncreasePost-fire 5 0.86 0.09
2011Pre-fire 6 0.87 0.08
-5.645 5 0.002* IncreasePost-fire 6 1.07 0.07
2012Pre-fire 6 1.07 0.07
-10.596 5 0.000* IncreasePost-fire 6 1.34 0.03
2013Pre-fire 5 1.33 0.03
1.880 4 0.133 DecreasePost-fire 5 1.26 0.06
2014Pre-fire 5 1.26 0.06
-2.636 4 0.058 IncreasePost-fire 5 1.39 0.05
2015Pre-fire 5 1.39 0.05
-7.372 4 0.002* IncreasePost-fire 5 1.65 0.05
2016Pre-fire 4 1.65 0.05
0.337 3 0.758 DecreasePost-fire 4 1.64 0.05
*Significantvariationbetweenmeanpre-fireandpost-fireorangutandensity
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4.Orangutanhomerange
a)
b)
c)
FigureA2.7:Annualhomerangesizeofadultandadolescent femalescomparedtothenumberof followswhenconsideringa)all individuals inthedataset(n=114),b)only individualswithastatusoffrequentorregular(n=68),andc)onlyindividualswithastatusoffrequent(n=25).Therelationshipbetweenthetwovariablesissignificantinallcircumstances(a:p<0.001;b:p<0.001;andc:p=0.038).
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a)
b)
FigureA2.8:Individuals’annualhomerangesizesfrom2003topre-fire2015fora)adultfemales(n=36)andb)adolescentfemales(n=19).HomerangesizedoesnotsignificantlyvarywithtimeforAF(R2=0.020;F(1,34)=0.680;p=0.415)orADF(R2=0.150;F(1,17)=2.992;p=0.102).
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TableA2.7:Annualandaveragehomerangesize(km2)forresidentadultfemalesduringpre-andpost-fire2015.Rangesizeisbasedonthemaximumconvexpolygon.
Name Year Status Homerangesize(km2)
Pre-fire2015
Feb
2010 Regular 1.32 2011 Regular 1.38 2012 Frequent 2.55 2013 Frequent 2.13 2014 Regular 1.50 2015 Regular 1.65 Average 1.75 SD 0.49
Gracia2012 Regular 1.54
2013 Regular 1.71 2014 Regular 1.71 Average 1.66 SD 0.10
Indah
2003 Frequent 0.43 2004 Frequent 1.75 2005 Frequent 2.26 2006 Frequent 2.45 2007 Regular 1.21 2008 Regular 1.90 2009 Regular 0.92 2012 Regular 1.16 2014 Regular 0.76 Average 1.43 SD 0.70
Indy
2012 Frequent 1.88 2013 Frequent 1.33 2014 Frequent 1.20 2015 Regular 1.13 Average 1.38 SD 0.34Post-fire2015
Feb2016 Regular 0.45
2017 Frequent 1.67 Average 1.06 SD 0.86 Gracia 2016 Regular 1.27 Indah 2016 Regular 0.91 Indy 2016 Regular 0.92
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FigureA2.9:AnnualhomerangesizebasedontheminimumconvexpolygonforGracia(residentadultfemale)from2012to2016.(n=numberoffollows/year:2012:n=15;2013:n=29;2014:n=14;2016:n=17)
FigureA2.10:AnnualhomerangesizebasedontheminimumconvexpolygonforIndy(residentadultfemale)from2012to2016.(n=numberoffollows/year:2012:n=41;2013:n=37;2014:n=34;2015pre-fire:n=16;2016:n=33)
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FigureA2.11:AnnualhomerangesizebasedontheminimumconvexpolygonforIndah(residentadultfemale)from2003to2016.(n=numberoffollows/year:2003:n=14;2004:n=54;2005:n=67;2006:n=44;2007:n=17;2008:n=15;2009:n=10;2012:n=14;2014:n=16;2016:n=15).