Late Quaternary vegetation and climate change in southeastern Australia: palynological evidence from marine core E55-6

Palynological analysis of core E55-6 obtained from off-shore western Victoria, provides a record of vegetation and climate change in the southeastern South Australian and western Victorian region spanning much of the last 125,000 yr. An accompanying oxygen-isotope record provides a chronology for the sequence. The pollen record suggests that maximum effective precipitation occurred during the height of the Last Interglacial (oxygen-isotope substage 5e), with wet sclerophyll forest and rainforest widespread in the region. Effective precipitation appears to have decreased during substage 5d promoting the expansion of dry sclerophyll communities, then increased slightly during substage 5c with the limited re-occurrence of welter forest types. Climatic conditions gradually became drier from substage 5b with the replacement of eucalypt dominated forest by more open heath and mallee type communities in the arid glacial conditions of isotopic stage 4. A brief phase of increased effective precipitation occurred during the interstadial stage 3, with limited expansion of Eucalyptus, followed by a steady decline in effective precipitation and the expansion of open heath and grass communities. Pollen is very sparse in the top section of the core, making environmental interpretation difficult. Nevertheless, it appears that grass and heath communities dominated the region during stage 2. There is no clear record of the Holocene due to the presence of mudflow sediments in the top of the core. The pollen evidence also suggests that continental shelf exposed as sea levels fell was colonised by a mosaic of coastal vegetation including Myrtaceae dominated scrub, eucalypt and Casuarina woodland, Asteraceae and Chenopodiaceae dominated heath and grassland. The charcoal record, expressed as a ratio to pollen concentration, gives evidence of increased burning during the height of the Last Interglacial period, most likely in response to increased fuel loads with the expansion of eucalypt dominated forest. This record also indicates a second phase of increased burning, commencing in stage 2, which gives possible evidence for increased anthropogenic activity in the region. (C) 1997 Elsevier Science B.V.