The Palaeovegetation of the Murray Basin, Late Eocene to Mid-Miocene

Abstract

The principles of pollen dispersal and deposition show that the pollen spectrum is produced by the plants of the locality, with a little transported in from long distances. The 'locality' has a radius of no more than 500 m, and it could be much less. Adherence to these principles has allowed a detailed reconstruction of the palaeovegetation.

Nothofagus grew throughout the Murray Basin, probably on the dry ground in the flood plain complex. Occasionally it was dominant, but most of the forests were mixed. The fusca-type flourished on well drained sites, especially in the north-east. The menziesii-type became prominent in the mid-Miocene, when the climate was becoming drier. The brassii-type was probably the only type in the deeper, swampier parts of the basin.

Gymnosperms were intimately connected with the semi-swamp forest. Araucariaceae–Casuarinaceae forests formed a coastal zone around the Miocene marine incursion. Herbaceous fresh water swamps were found in the north-west, where they formed disjuncts from the swampy margin of Lake Frome. Myrtaceae was found throughout, sometimes abundantly, but eucalypts were rare.

Geographic variation, changes through time and forest dynamics, including possibly one very rare modification after burning, are detailed.