“I see Country as the world around us, what we live in, but also ourselves. Everything is Country…”

Michael-Shawn Fletcher

These sediment cores form the foundation for the work undertaken by Wiradjuri geographer and academic Professor Michael-Shawn Fletcher and his team, who extract these samples from wetlands to reveal hidden stories within their layers.

Preserved through compression and oxygen-free environments over centuries, these cores speak through the sediment, microfossils and charcoal trapped within them, making what Dr Fletcher describes as ‘a sedimentary storybook’.  

Through analysing this material Dr Fletcher uses modern science to study ancient science, finding a wealth of evidence that attests Aboriginal land management practices, most pertinently, the application of cultural burning regimes.

This work speaks to our past, our present and, perhaps most importantly, provides scientific evidence that may guide our future in paving the way for cultural burning practices to be more widely understood and re-invigorated.

WHAT ARE THEY MADE OF?

Sediment cores are long cylinders of the earth’s crust drilled up from beneath the ground. Inside these muddy cores are clues about our environment’s history stretching back several millennia. By analysing the sediment from the traces of pollen, charcoal, organic matter, and DNA of micro-organisms we can learn more about how the environment has changed over time.

At the top of the core it looks jet black and as we make our way down the core it becomes a lighter brown. Why do we think the top of the core is a jet black colour? This represents sedimentary changes from less biomass, less forested/wooded and more grassy landscapes (lighter brown) to more biomass, more forested/wooded landscapes (jet black).

The bottom represents pre colonisation when Aboriginal people cared for managed the environment (i.e., Country). The soil is a lot healthier and there is more diversity of pollen and organic matter which shows us greater biodiversity in vegetation.

HOW ARE THE SEDIMENT CORES STUDIED?

Once extracted from wetlands the sediment cores are transported to the Palynology laboratory at the University of Melbourne and split into two halves. One half is retained for analyses and sampling for dating, pollen and charcoal in the laboratory and the other half is kept as an archive and sent for non-destructive analyses.

Some cores are split under red light to be able to conduct certain analyses that are sensitive to regular light/sunlight (e.g., Optically Stimulated Luminescence dating). The cores are then inspected for visual changes in the layers and wrapped for storage in the laboratory cool room.

WHAT CAN WE LEARN FROM THEM?

Michael and his team extracted 1m deep sediment cores from sites in Tasmania to analyse how colonisation has altered the landscape.. To do so, they analysed pollen to see changes in management approaches and ecosystems throughout time (e.g., changes from open grasslands to closed rainforests). They found that there was a “major ecological shift following European colonisation”.

Across Australia, the sites studied to date by the team show that they only experienced minor fires as they were kept open by Aboriginal land care for Country and management but now ecosystems are characterised by major and/or catastrophic fires and much denser shrub and forests. Scientists analyse the cores for macroscopic charcoal particles to reconstruct when fires occurred and how intense they were throughout history.

SIGNIFICANCE OF THE CORES

The sediment cores on display were collected by Dr Fletcher and his team from field trips to Red Belly Billabong and Tooculerdoyung Lagoon on GunaiKurnai Country in Gippsland, as well as Central Plateau and Surrey Hills on Palawa Country in Tasmania.  

When samples are taken from the cores, chemically processed and magnified under a microscope they reveal what the landscape was like hundreds to thousands of years ago, as you can see in the images below.

Pollen (shown in the images below) is produced by plants and is transported by the wind, insects, or other animals. It is constantly in the air and gets deposited in wetlands and preserved in the mud that Dr Fletcher and his team extract as sediment cores. By analysing pollen the team can understand past climates and environments by identifying plants that were growing at different times.

HOW THESE TELL US ABOUT FIRST NATIONS FIRE MANAGEMENT?

By studying the materials extracted from the sediment cores, we begin to build a picture of how land was managed at that time in history. It gives an indication of who was living on the land and how they interacted with it, as Dr Fletcher explains below.

All of Australia is occupied by people, by Aboriginal and Torres Strait Islander people, who have a sophisticated and deep connection with fire, and an application of fire in the landscape.

Michael-Shawn Fletcher

Thousands of years of Care for Country and sustainable land management, informed by scientific, ecological and agricultural knowledge has nurtured and maintained Country for 350+ diverse Indigenous language groups. And yet, since Invasion, the complex and detailed knowledge and expertise of Australia’s First Peoples has been little known – dismissed, silenced and largely ignored.

We invite you to question historical erasures and to recognise the contemporary circumstance they enable. What have you learnt in school about the people on whose lands you live, study or work? What do you know about Australia’s Indigenous peoples, our knowledge and the ways we express our culture and obligations to Country today? What do we continue to risk in failing to recognise Indigenous knowledge and sustainable practice in the ongoing care for and management of Country?

The sediment cores assert First Nations contribution to present day culture, with knowledge from communities nurturing Country despite the ravages of colonisation.

COMMUNITY CONSULTATION WITH INDIGENOUS GROUPS/ELDERS

At the core of the work that we do with palaeoecology and understanding changes in pre- and post-Invasion landscapes is collaborating with traditional owners across southeast Australia.

The knowledge of Indigenous fire practices persists in varying formats among many Indigenous peoples. An opportunity exists to authentically engage in shared stewardship with local Indigenous communities to promote cultural exchange, healing, and movement beyond dated ideas of wilderness.

Integrating diverse knowledge systems reduces uncertainty about past environmental conditions and how they were shaped through traditional land-use practices, thereby enabling improved understanding of the range of future potential conditions and how we might engage in environmental stewardship to guide future change.

When we wish to collect sediment cores from sites across Australia we firstly contact the local Aboriginal group for that area. We engage in a conversation, a yarn, about what they want to get out of such research, what questions are important to them to be answered about their Country through our research. We develop and sustain co-constructed research into understanding, primarily, whether fire and vegetation has changed (via palaeoecology) and how Country has changed pre- and post-British Invasion to better inform management of Country. The on-Country yarning sessions, that are central to our research approach, are used to facilitate and foster a relationship between the University and the communities. These yarning sessions facilitate co-designed research agendas to propagate a continuing relationship between research and the communities. Transdisciplinary partnerships are paramount to facilitate Indigenous leadership and empowerment in the design of research programs that support their aspirations for Country.

Video, audio & image credits

Audio 1: Recorded by Maddison Miller for Emu Sky exhibition

Video 1: Michael-Shawn Fletcher

Video 2: Michael-Shawn Fletcher

Set of 3 photos: Ollie Kamien-Sarbinowski

Video 3: Michael-Shawn Fletcher

Pollen photos: Anthony Romano