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BLUMEA 45 (2000) 427-432 Borassodendron(Palmae) in theSoutheast Asian fossil pollenrecord B.K. Maloney ThePalaeoecologyCentre,Queen's University, Belfast,Northern Ireland Summary Borassodendron machadonispollenoccurredthroughouttheHolocene pollenrecord ofNongThale SongHong,Thailand,until about 4000BP.Itwas alsopresentin onesamplefromKhokPhanom Di,Thailand,and in the Mahakam Delta,Kalimantan,records, but B. machadonis has notbeen reportedfromthe modern floraofKalimantan. Borassodendron machadonis pollendiffersgreatly from that ofB.borneense, which is foundonthe island ofBorneo. Key words: Borassodendron,fossilpollen, Indonesia,Thailand. Thereare two species in the genusBorassodendron, B.borneenseJ. Dransf.andB. machadonis(Ridl.) Becc. (Palmae: Coryphoideae:;),andthey differinpollen morphol- ogy (Ferguson etal., 1987). Borassodendronborneense is monolete(monosulcate) (Ferguson etal., 1987,f. 1A-F),whileB. machadonisismonoporate(Thanikaimoni, 1971,pi.X: 178-184;Ferguson etal., 1987,f.2A-G). Thepollen grainsofbothare large anddistinctive.BorassodendronmachadonishasasouthernThailand-northern PeninsularMalaysia distribution,andseemedatonetime toberestrictedto slopes at thefootoflimestone(Dransfield, pers. comm.), but also occurs in hill dipterocarp forestonshalesinKelantan.Borassodendronborneensisis only knownfromBorneo [north-westaccording to Dransfield(1979); but Whitmore(1978) says north-east, anddoesnot mentionthenorth-west,citeDransfield] whereitis widespreadbutalways quitelocalisedandabsentfrommanyplaces suitableforits growth. Thedistribution may havebeenalteredby maninsome areas(Dransfield, 1972)as theapexis eaten by humans, who even cut the juveniles. Borassodendron borneensis differs from B. machadonisinthat ithasamuchsmallermaleinflorescence, withsix stamens,as opposed tonine tofifteen,hasasmallerfemaleinflorescence,and variessomewhatin leafmorphology. Bothare unarmed,dioecious,solitary fanpalms upto20 mtall. Borassodendronpollen has been reported from the Mahakam Delta, Kalimantan (Cartini& Tissot, 1985) andthefossil pollen is illustratedon theirplate IV: 10, 11. TheseillustrationsdemonstratethatitwasB. machadonisandnotB. borneensepollen. Itseems tohavebeen absentfrommodernpollen samples andtohavebeen grouped withtheotherPalmaepollen inthepublished pollen percentages.Palmpollen occurs fairlycontinuously throughoutarecordrangingfromtheUpper Pliocenetothepresent butonlyNypahasbeenrecordedseparately anditisthereforenot possible tocomment uponits distributionpattern throughout thecore. t Deceased on 11October 2000. 428 BLUMEA Vol. 45, No. 2, 2000 Fig. 1.NongThale SongHong:topography. B.K.Maloney: Borassodendron in the Southeast Asianfossilpollenrecord 429 Asingle grainofBorassodendronmachadoniswas foundinthe3.99msamplefrom core BMR2(Maloney, 1991)extractedthrough arice fieldnorthofthearchaeological siteofKhokPhanom DiintheBang PakongValleyofeast centralThailand.Smitinand (1980)recorded onlyTrang andPattaninames forthespecies, anditis likely that the palmwas notgrowing inthisareabutthatthepollen wastransported thereby coastal currents. Thepollenspectrum was dominatedby Rhizophoraceae andthesediments consistedofgreen,finegrained, shallowwater marineor inter-tidalclays. InthelackofmoreinformationabouttheKalimantancore, themostcontinuousrecord ofB. machadonisseems tobemine fromthesmall, shallowlake calledNong Thale Song Hong which is located at7° 52'N, 99° 28' 50"E in TrangProvince, north of Trang. Thissiteisatabout 100maltitudeandhas nooutflowing orinflowing streams. A3m core wasextractedby Dr.LisaKealhofer(College ofWilliam&Mary,Virginia) Table 1.Borassodendron machadonis pollenatNongThale SongHong,South Thailand,and its estimated age. Samplenumber Depth(mm) Estimated age Percentageoftotal Pollen concentration/cc pollenand pterido- phyte spores 1 55 400 0 0 2 105 764 0 0 3 155 1128 0 0 4 205 1492 0 0 5 255 1855 0 0 6 305 2219 0 0 7 355 2583 0 0 8 405 2917 0 0 9 455 3311 0 0 10 505 3674 0 0 11 555 4038 1.87 880 12 605 4402 0.48 142 13 655 4766 1.46 735 14 705 5130 0.44 327 15 755 5493 0 0 16 805 5857 0.48 179 17 855 6221 0 0 18 905 6568 0.84 466 19 955 6908 1.84 501 20 1055 7588 0.98 276 21 1105 7928 0.49 201 22 1155 8268 0.43 320 23 1205 8608 0 0 24 1255 8948 0.86 279 25 1305 9288 0 0 26 1355 9629 0 0 27 1405 9968 0 0 28 1455 10308 0 0 29 1505 10648 0 0 430 BLUMEA Vol. 45, No. 2, 2000 Fig.2.NongThale SongHong.Borassodendron machadonispollenconcentrations/cc (a)andpollen percentages(b). andDr. JoyceWhite(UniversityofPennsylvania Museum) inDecember 1994where thewater was atitsdeepest usingamodifiedLivingstone piston sampler. Thepartof thecore pre-dating around 10,650BP was largely devoidofpollen, but asequence covering thecomplete Holocenecouldbereconstructed, although noneofthesamples wasespecially pollenrich, andthesedimentationrateproved so slowthatthesampling intervalof5 cm yielded dataofrathercoarse resolution. Nevertheless, thevegetation couldbe seentobeinastateofconstant flux,partlydueto burning,whichwas proba- blyofbothnaturalandhumanorigin. Thenature ofthesite(Fig. 1)precludes straight- forwardrecognition ofclimaticchanges butis idealforinvestigating localvegetation changes, bothhydroseralandon theadjacent slopes. Thelakeis surroundedby steep slopes, with alowaltitudeplateau above these.The highestpoint intheregion only reaches up to400mandis situated 14km tothesouth-westofthesite. B.K.Maloney: Borassodendron in the Southeast Asianfossil pollenrecord 431 Theapproximate agesof the samples in whichBorassodendronpollen grains occur hasbeenestimatedusingtwoAMSradiocarbondatesof10,820+50BP(Beta-Analytic 106537) from 156-160mm depthand6330± 50 BP(Beta-Analytic 106539) from the 84-90 mm level, disregarding the errors of the determinations.Both dates are uncalibrated and the sedimentwas pre-treated at Beta and fed through the mass spectrometer atOxford. Borassodendronfirst enteredtherecordaround 8950 BP(Table 1,Fig. 2)andhad analmostcontinuous,butlow level,record untilabout 4000BP, after which it disappeared entirely. However, its highest percentage and concentrationfiguresare inthisfinalsample. Itsdisappearance fromthe pollenrecord couldrelate to forest clearance, or a combinationofforest clearance and climatic change,eitherintermsofmacro-climateor inedaphic conditions.Microfossilcharcoal peaks becamemorefrequent then,as diddisturbanceindicatorssuch asMacaranga/ MallotusandUrticaceae/Moraceae,buttherewas also quiteasignificant onearound 8600 BP. Disturbance indicators werealso commonerin manyof theearlier levels whereBorassodendron representation was depressed but there is not a consistent correlationbetweenallofthecurves. Atthemoment thisrecord isof interestfromaphytogeographical pointof view, but Borassodendronmachadonisis veryrareinThailandandPeninsularMalaysiatoday, hasa large, very distinctive pollen, cf. Ferguson et al.(1987) and couldbe auseful indicatortypeifmorewasknown ofitspresent-day ecology. Smitinand(1976)found thisspecies at120-160maltitudeintheSurinIslands, similarheightstothoseofthe study region, but itmightbe confinedtolocations where the soilsarebase rich, the shalesmentionedby Dransfieldmaynot beparticularlyacid, ortorequire aparticular amount ofmoisture.As ithasbeenfoundinbothlowlandandhillforestitmaynot be especially temperaturesensitive. ACKNOWLEDGEMENTS ThisresearchwasfundedbyNational Geographicandfieldwork wasconducted under theauspices ofthe National Research Council ofThailand. Theauthor wasunable tobeinvolved in fieldwork for logistic reasonsbut thanks Dr. Lisa Kealhofer,CollegeofWilliam and Mary, Williamsburg, Virginia, and Dr. JoyceWhite, University ofPennsylvania Museum, forcollecting the coreand providingvaluable backgroundinformation,particularly Dr.Kealhofer who has kept in constant touchbye-mail duringthecourseoftheanalyses. Research onthe813Crecord ofthesite isbeing carriedout atthe PalaeoecologyCentre,TheQueen'sUniversity, Belfast, underthe direction of Dr.F.G.McCormac. REFERENCES Caratini,C.& C.Tissot. 1985.LeSondageMisedor,etudepalynologique.Etudes deGeographie Tropical,Bordeaux: Centre Nationale deRecherche Scientifique. Dransfield,J.1972.The genusBorassodendron (Palmae)inMalesia. Reinwardtia 8: 351-363. Dransfield,J.1979.AManual oftheRattansoftheMalayPeninsula. Malaysia:ForestDepartment. Ferguson,I.K.,A.J.Harvard& J.Dransfield. 1987.Thepollenmorphologyofthe tribeBorasseae (Palmae:Coryphoideae).KewBull. 42: 405-422. 432 BLUMEA—Vol. 45, No. 2, 2000 Maloney,B.K. 1991.Palaeoenvironments ofKhokPhanom Di:thepollen,pteridophytespore and microscopiccharcoal record.In:C.F.W.Higham&R.Bannanurag(eds.),Excavation ofKhok PhanomDi,Vol.2 (Part 1)TheBiological Remains: 7-134. Society ofAntiquariesofLondon, London. Smitinand,T. 1976.Apreliminary study ofthe vegetation ofSurin Islands. Nat. Hist. Bull. Siam Soc. 26: 227-246. Smitinand,T. 1980.Thai Plant Names (BotanicalNames-Vernacular Names). Bangkok: Royal Forest Herbarium. Thanikaimoni,G. 1971.Les Palmiers: PalynologieetSystematique.These,Docteur des Sciences Naturelles,Universite deMontpellier. Whitmore,T.C. 1978.Palms ofMalaya. KualaLumpur: OxfordUniversity Press.