Fire and ecosystem change on Kangaroo Island, South Australia, over the past 5,000 years

Fire has long been a familiar and important part of Australian landscapes. However, anthropogenic climate change has heralded major shifts in fire regimes, negatively impacting ecosystems. These effects are expected to worsen in coming years, but there remain difficulties with projecting fire regime trajectories and their environmental impacts, in part due to a lack of data on centennial to millennial timescales. Uncertainties remain concerning the independent effects of climate and human impact on bushfires, and the long term impacts of fire on both terrestrial and aquatic ecosystems. This study aims to address these uncertainties by returning to Lashmars Lagoon, Kangaroo Island, a site of pioneering palaeoenvironmental research in South Australia. Kangaroo Island presents a fascinating case study, due to the putative abandonment of the island by ancient Aboriginal populations 2,450 ± 300 cal yrs BP. As such, it represents a unique opportunity to study the impact of cessation of Aboriginal management practices on ecosystems prior to European invasion. We collected sediment cores from Lashmars Lagoon, which we estimate to span the past 5,000 years. We are combining multiple palaeoecological and geochemical proxies to infer both fire and hydroclimate variability, augmented by an age model based on Pb-210, Pu isotopic profiling and C-14 dating. We will also analyse sedimentary ancient DNA (sedaDNA), which we hope will provide novel insights into the occurrence of taxa not usually detected through conventional palaeoecology. Our aim is to provide insights into the drivers of palaeofire and ecosystem response to changing fire regimes, with relevance to contemporary bushfire predictability and environmental management. For this conference, we will present preliminary data with a particular focus on the recent historical period. The potential and challenges of using lake sedaDNA in an Australian context will also be discussed. © The Authors.

Keywords

Fires, Islands, South Australia, Australia, Ecosystems, Climates, Humans, Environment, Aquatic ecosystems, Carbon 14, DNA

Citation

Duxbury, L. C., Tyler, J. J., Ambrecht, L. H., Francke, A., Cadd, H R., Law, W. B., Zawadzki, A., Child, D., Gadd, P., Jacobsen, G., Tibby, J., & Mitchell, K. J. (2021). Fire and ecosystem change on Kangaroo Island, South Australia, over the past 5,000 years. Paper presented to the Australasian Quaternary Association/Friends of the Pleistocene Pop-up Conference 2021, 8-9th July 2021. Retrieved from: http://aqua.org.au/wp-content/uploads/2021/07/Abstract-book-2021-1.pdf

URI

http://aqua.org.au/wp-content/uploads/2021/07/Abstract-book-2021-1.pdf
https://apo.ansto.gov.au/handle/10238/15558

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