Shaping a sunburnt country

Fire, climate and the Australian landscape

Fire has shaped the Australian landscape, biodiversity and resources for millennia and in south-eastern Australia, it is the dominant ecological disturbance and a prominent natural hazard.

We only need to look at our most recent bushfire crisis of 2020 where the scale of fire devastation can be understood by looking at the area that was burnt: more than 12.6 million hectares across Australia and 5.4 million hectares in New South Wales alone. Compared to a typical fire season of around 300,000 hectares in NSW, it has been an extraordinary and unprecedented summer in Australia that has raised many questions about the changing nature of fire. 

Our ability to sustain biodiversity, maintain and enhance terrestrial carbon storages (above and below ground) relies on our understanding of how climate, ecosystems (including humans) and soil resources are linked. 

Consideration of how fire might have changed is paramount to a better understanding of the present and future of the Australian environment. 

Relatively short periods (20-40 yr) of fire data such as area burned and fire severity, are increasingly being used in comparison with weather variables (e.g. temperature, rainfall) to scrutinise current and potential future effects of climate change on fire activity in temperate forest and shrub land ecosystems here in Australia and across the globe. However, for researchers to provide more robust and accurate future predictions of environmental changes caused by climate and fire activity, we need to go beyond 20-40 years of data.  

A research team at UOW led by Prof. Anthony Dosseto and Senior Prof. Ross Bradstock has recently been awarded an ARC Discovery Project grant (2019) to develop novel tools to identify the intensity and severity of past fire events in Australia, and produce a 100-year record of fire history in south eastern Australia. 

The five-fold extension of our knowledge of fire trends and regimes from this research will improve the ability to forecast how things will change in the future. 

“The project will help us answer critical questions such as: Has climate change caused a change in fire regime over the last 100 years in Australia? Has there been an increase in high severity fires (i.e. fires burning to the forest crown)? To answer those questions we’ll be investigating relationships between areas of recent fire events and the deposition of sediments in reservoirs in forested catchments," said Prof. Dosseto. 

“We will be developing new tools which use the physical and chemical characteristics of charcoal and sediments, to inform on the nature of past fires. These tools will be first calibrated, by applying them to sediment deposits that record recent, known fires. The new tools will evaluate how fire activity, soil loss and development have varied over the last century and provide a better understanding of the interaction between climate, fire and soil.” 

In 2018 Senior Prof. Ross Bradstock established the new NSW Bushfire Risk Management Research Hub at UOW with funding from the NSW Office of Environment and Heritage (now the Department of Planning, Industry and Environment). His expertise has focussed on risks posed by bushfires to human and environmental values and ways these risks can be mitigated, particularly under climate change. 

“Anthony approached me about developing new methodologies that help us to better understand how fire regimes have changed in the past in response to changes in human activity and climate. This led us to discuss interesting opportunities to develop and test these possibilities. The use of reservoirs and their trapped sediments provides a great opportunity for such work because we have some knowledge of fire patterns in recent decades that can be used to calibrate the signatures that we might find in the soils and sediments in these catchments. It enables us to harness the collective strengths of our research teams,” said Prof. Bradstock.   

This ARC Discovery Project brings together experts in fire ecology, geochemistry, charcoal and Quaternary science, from Australia and France. Participants are: Prof. Anthony Dosseto (UOW), A/Prof. Scott Mooney (UNSW), Senior Prof. Ross Bradstock (UOW), Dr Damien Lemarchand (University of Strasbourg) and Dr Nathalie Vigier (CNRS- Oceanographic Laboratory of Villefranche). The team also includes 2 PhD students, and an Honours student, who will be involved in much of the field work and analysis.