The last glacial cycle from Wyelangta, the Otway region of Victoria, Australia

Abstract

This paper presents the first long Quaternary palynological record from the Otway region of Victoria, an area which is biogeographically important in that it is an outlier of the southeastern highlands containing distinctive forest vegetation with great similarities to the island of Tasmania. The record is derived from a small remnant patch of cool temperate rainforest dominated by Nothofagus cunninghamii surrounded by tall open eucalypt forest. Three clear phases are identified: an older rainforest phase dated to beyond 40,000 years BP which probably represents the latter part of Oxygen Isotope Stage 5; a phase of more open vegetation which covers at least part of the last glacial period; and a younger rainforest phase of Holocene age. The record is significant in providing refinements to late Quaternary climatic estimates from southeastern Australia utilising the climatic profiles of key rainforest taxa, and in indicating the likely presence and nature of a glacial rainforest ‘refugium’. The occurrence of a major rain forest tree, Phyllocladus, during the early forest phase and of the subalpine taxon Gunnera, during the last glacial period, taxa now restricted to Tasmania, demonstrates an even greater biogeographic link to this island in the recent past. Their extinction on the mainland is consistent with the general demise of cool temperate taxa with close Gondwanan affinities on the Australian mainland through the Late Cenozoic period. Their late disappearance contributes to the growing list of mainland extinctions of ancient and geographically interesting taxa adding weight to the proposal that Aboriginal burning has had a substantial impact on the Australian landscape during the last glacial cycle.