Reconstructing past fire and ecology on Kangaroo Island during theHolocene

Kangaroo Island - it’s about as quintessentially Australian as a placename gets. There should be no surprises then when I tell you that I’m from the University of Adelaide, South Australia. I’m completing a Master of Philosophy in Earth Sciences with a focus on paleofire and I’m excited to be able to connect with the French bushfire community, especially as I lived in France for a year in Aix-en-Provence and Grenoble.

Last summer, as I’m sure you did, I watched with baited breath as my country burned out of control for months. Friends lost their vineyards in the Adelaide hills, family was evacuated from the Victorian high country and the air quality was so bad that I couldn’t work out if it was healthier to go for a run or stay inside on the couch. It was petrifying but ultimately these events were a spark of inspiration for my current research on the fire history of Kangaroo Island, especially as nearly half the island was burnt in the blaze.

Of course, fire has long been a familiar and important part of Australian ecosystems. However, anthropogenic climate change has heralded major shifts in fire regimes, negatively impacting ecosystems and threating human lives. Destructive megafires are predicted to increase in coming years; the summer of 2019/2020 was already amongst the worst witnessed since European arrival in Australia.

Despite these projections, there is still considerable uncertainty surrounding fire regime trajectories and their corresponding environmental impacts. This is due partly to a lack of historical data on centennial to millennial timescales. In South Australia, the driest state on the driest inhabited continent, the problem is exacerbated. This is because permanent bodies of water, and therefore continuous paleoenvironmental records, are few and far between.

Lacustrine sediments on Kangaroo Island are exceptions to this rule and provide otherwise unattainable Holocene records for the South Australian region. Our study aims to address the research gap by analysing lake sediment cores from Kangaroo Island. In September this year, we collected several lake sediment cores from Lashmar’s Lagoon on eastern Kangaroo Island, reaching a maximum depth of 7.39 metres, likely representing the past ca. 5000 years (about half of the Holocene). We have further plans to collect additional cores from Grassdale Lagoon in the far west of the island and the more central Birchmore Lagoon in early 2021. I’m hoping that we have enough arm strength to push further through the Holocene at these sites! On all of our cores, we will be conducting high-resolution charcoal, sedimentary ancient DNA (sedaDNA), pollen and geochemical analyses to elucidate the complex interactions between climate, fire and the environment.

Kangaroo Island is also unique in that it is believed to have been largely uninhabited and unmanaged by Aboriginal people for millennia. Our results could therefore offer important insights into ecological baselines and the effects of cessation of Aboriginal fire management on ecosystems. As I also am interested in Aboriginal knowledges, it is a long term goal of mine to further explore the role of Aboriginal burning practices in ecological management.

More generally, I am fascinated in the relationship between western science and Aboriginal knowledge systems, especially where they are complementary. Aboriginal Peoples have been sustainably managing Australian landscapes for a very long time and it is disappointing that their knowledge systems are all too often disregarded.

I embark on this research journey with hope that the knowledge I gather of the past can inform present and future bushfire predictability as well as ecological management and restoration. I very much look forward to learning more about others’ work in this space too.

I have to say here that my favourite part about talking about my research in French is that these are not sediment ‘cores’ but ‘carrots’

Contact: lucinda.duxbury@adelaide.edu.au