A >43,000-year vegetation and fire history from Lake Baraba, New South Wales, Australia

Abstract

Palaeoenvironmental sequences that describe the vegetation of the last glacial maximum (LGM) and of the subsequent climatic amelioration are relatively rare in the Australian, Southeast Asian and Pacific region (SEAPAC region). Here, we present the results of a palynological investigation from Lake Baraba, located in eastern Australia, which extends beyond 43 ka. Bands of oxidised sediment prior to the LGM suggest lake level fluctuations, however, lacustrine clays continued to be deposited throughout the LGM and into the early Holocene when the deposition of peat was initiated. The vegetation, a Casuarina woodland/shrubland with a mixed understorey, remained relatively stable from >43 kyr to the early Holocene, suggesting that this sclerophyllous vegetation was resilient to changes in climate. The vegetation of the LGM at Lake Baraba does not conform to previous descriptions of a treeless south-eastern Australia, and it is possible that it was a refugium for woodland. Myrtaceae expanded at the expense of Casuarinaceae from the early Holocene, with charcoal analyses suggesting that fire was an unlikely explanation. There was no apparent relationship between Aboriginal site usage and fire activity and hence how Aboriginal people used fire at Lake Baraba remains speculative.