QA_Vol 24_No 1_July 2007 - Australasian Quaternary Association

Thesis AbstractsA Late Quaternary palaeoenvironmentalinvestigation of the fire,climate, human and vegetationnexus from the Sydney Basin,AustraliaMANU P. BLACK (PhD)University of New South WalesIt is widely believed that Australian Aboriginalsutilised fire to manage variouslandscapes however to what extent thisuse of fire impacted on Australia’secosystems remains uncertain. The latePleistocene/Holocene fire history fromthree sites within the Sydney Basin,Gooches Swamp, Lake Baraba and KingsWaterhole, were compared with archaeologicaland palaeoclimatic data using anovel method of quantifying macroscopiccharcoal, which is presented in this study.The palynology of the three sites was alsoinvestigated. The Gooches Swamp firerecord appeared to be most influenced byclimate and there was an abrupt increasein fire activity from the mid-Holoceneperhaps associated with the onset ofmodern El Niño dominated conditions.The Kings Waterhole site also displayedan abrupt increase in charcoal at thistime however there was a marked decreasein charcoal from ∼3 ka. SimilarlyLake Baraba displayed low levels ofcharcoal in the late Holocene. At bothKings Waterhole and Lake Baraba archaeologicalevidence suggests intensifiedhuman activity in the late Holocene duringthis period of lower and less variablecharcoal. It is hence possible that Aboriginalpeople dominated fire activity in thelate Holocene perhaps in response to theincreased risk of large intense fires underan ENSO-dominated climate becamemore prevalent. The fire history of theSydney Basin varies temporally and spatiallyand therefore it is not possible touse a single type of fire regime as amanagement objective. There were nomajor changes in the composition of theflora at all sites throughout late Pleistocene/Holocenealthough there were somechanges in the relative abundance ofdifferent taxa. It is suggested that theSydney Sandstone flora, which surroundsthe sites, is relatively resistant to environmentalchanges. Casuarinaceae waspresent at Lake Baraba during the LastGlacial Maximum and therefore the sitemay have acted as a potential refugiumfor more mesic communities. There was anotable decline in Casuarinaceae duringthe Holocene at Lake Baraba and KingsWaterhole, a trend that has been found ata number of sites from southeasternAustralia.Late Quaternary Environmentsand Climate History at Lakes Bolacand Turangmoroke, WesternVictoria, AustraliaELLYN J. COOK (PhD)Monash UniversityA palaeoecological record produced fromLakes Bolac and Turangmoroke detailsthe changing nature of vegetationpatterns, lake levels and climate in thedrier part of the Victorian Western Plainsover approximately the last 90,000 years.In addition to the routine palynologicalproxies of pollen, spores and charcoal, arange of non-pollen palynomorphs wasanalysed and their usefulness aspalaeoecological indicators in Australiawas evaluated. A range of transferfunctions was also developed to relatemodern (pre-European) pollendistributions to climatic parameters inmainland southeastern Australia. Thefunctions that reconstruct summer,annual and winter rainfall andtemperatures were found to be the mostrobust while temperature of warmest andcoolest periods, and moisture indexes arealso strong. Application of the functionsto the fossil data from Lakes Bolac andTurangmoroke produced estimates whichare corroborated by trends seen in otherlines of evidence, confirming this newapproach as an additional reliabletechnique for quantification of the pastclimates of mainland southeasternAustralia.During marine isotope stage (MIS) 5.1and mid MIS 3 the palaeoecologicalrecord indicates regional vegetationcomposed of open woodland dominatedby Allocasuarina luehmannii type with lownumbers of Banksia, Eucalyptus andother Myrtaceae under which a diverseunderstorey developed. During thesetimes Lake Turangmoroke held freshwater of varying depths. Estimatesderived from pollen data show theseperiods received annual precipitationhigher than today which was moreequally distributed between summer andwinter. Strong contrast in seasonaltemperature extremes during MIS 5.1appears to relate to corresponding peaksand troughs in insolation received at thesite. The degree of representation of MIS4 and MIS 3 in the record is uncertainowing to discontinuities resulting fromthe lake having periodically dried.Luminescence dating indicates a changeto open grassland-steppe occurred shortlyafter 47,000 years BP and lake levelsfluctuated considerably before the lakebecame shallow and saline. Opengrassland-steppe continued through MIS2 with almost no presence of trees whilethe aquatic flora reflected further lakelevel declines and increasing salinity.Driest conditions, indicated by deflationof lake sediments during lunettebuilding, are dated to between ∼18000and ∼11000 years BP. Open woodland inthe early Holocene was dominated byAllocasuarina verticillata type until partialreplacement by Eucalyptus around7–8000 years ago when the vegetationcover present at European arrival wasestablished. Increased contrast betweensummer and winter precipitation andmuch reduced contrast in temperatureparameters marked the establishment ofpresent day climatic patterns for this partof Western Victoria. Considerableevidence for mean annual temperatureshigher than today in the early Holocene,increased regional precipitation duringthe mid Holocene and late Holocenedrying suggested by other studies fromthe region was discernable in thepalaeoecological record, lake level historyand the quantitative climatic estimatesfrom Lakes Bolac and Turangmoroke.Comparison of the palaeoecologicalrecord with those from Lakes Wangoomand Terang on the wetter part of thewestern plains shows good correspondencein the upper parts of the sequencesbut, beyond this, a lack of reliablechronologies for the latter recordsprevents the establishment of absolutecorrelations. However, changes invegetation and climate patterns weresufficiently distinct to allow explorationof climate forcing and representation inall three sequences was found to followchanges in the southern hemispheremid-latitudinal westerly circulation.This finding suggests that patterns ofvegetation change recorded in pollenrecords from southeastern Australia arestrongly influenced by local insolation inaddition to northern hemisphere forcing.Environmental Boundaries in theSydney Basin during the HoloceneROSALIND JAMES (PhD)School of Human and Environmental Studies,University of New EnglandThis thesis tests selected environmentalindicators against a chronological recordderived from estuarine sediments inorder to assess the possibilities ofdisentangling human from naturalimpacts on the environment in theSydney region during the mid to lateHolocene. Results show that46 | Quaternary AUSTRALASIA 24 (2)