Tertiary climate and phytogeography in southeastern Australia

Abstract

Palynofloras of late Eocene to Pliocene-Pleistocene age have been used to reconstruct vegetation and climate in southeastern Australia. The vegetation was forest, becoming open only in the late Pliocene-early Pleistocene. Precipitation was the highest in the late Eocene-early Oligocene, decreasing in the late Oligocene-early Miocene and mid Miocene, with a brief increase in the late Miocene-early Pliocene and subsequent further decreases. Patterns of change show a retreat of rainforest taxa from a formerly widespread distribution to their present restricted habitats, e.g. the Huon Pine (pollen type Phyllocladidites mawsonii) to Tasmania and the Araucariaceae to the northern part of the east coast. Other taxa may be abundant, under certain ecological conditions, e.g. Nothofagus flemingii on well drained soils and Casuarinaceae in marginal marine regions. The Miocene was a time of great change and maximum variation, when widespread rainforest disappeared from inland regions and burning on a regular basis became an integral part of the environment. Throughout the time period under review, there was a climatic gradient parallel to that of today.