Australia: The Land Where Time Began

A biography of the Australian continent 

Lake Baraba - A Vegetation & Fire History Going Back More Than 43,000 Years

In this article Black_, Mooney & Martin¹ present the results of their palaynological study from Lake Baraba, New South Wales, extending back more than 43,000 years. They say it is relatively rare to find palaeoenvironmental sequences in Australia, Southeast Asia and Pacific region (SEAPAC) from which the vegetation of the last glacial maximum (LGM) and subsequent amelioration of the climate can be described. Lake level fluctuations are suggested by bands of oxidised sediments that were deposited before the LGM continued deposition of lacustrine clays throughout the LGM and into the Early Holocene, after which peat deposition was initiated. The vegetation consisting, of Casuarina woodland/shrubland with a mixed understorey, continued to be relatively stable from prior to 43,000 years ago to the Early Holocene, suggesting that this sclerophyllous vegetation was resilient to climate change. Black, Mooney & Martin suggest the vegetation of Lake Baraba during the LGM may have been a refugium for woodland, as it does not conform to earlier descriptions of the vegetation of southeastern Australia as being treeless. Beginning in the Early Holocene Myrtaceae expanded and replaced Casuarinaceae, fire being an unlikely explanation based on the analysis of charcoal from that time. Black, Mooney & Martin found no evidence of a relationship between the usage at Aboriginal sites and the fire activity. The way in which the Aboriginal people used fire in the Lake Baraba area is still speculative.

Sources & Further reading

1. Black, M. P., S. D. Mooney, and H. A. Martin. "A >43,000-Year Vegetation and Fire History from Lake Baraba, New South Wales, Australia." Quaternary Science Reviews 25, no. 21–22 (11// 2006): 3003-16.