Fire

Introduction – Fire

In what ways and to what extent has c. 65,000 years of Aboriginal burning influenced historical vegetational change and the current composition and distribution of the Australian biota? Any views on pre-European Aboriginal fire management and its effects on the landscape are important for the politically charged arena of modern fire-management regimes in particular the assumption that Aboriginal-like fire management, especially the use of low intensity fires, could prevent modern extreme bushfires. The topic of fire-stick farming and its impacts is not only controversial but also currently open to wide scientific interpretation. When the first Europeans arrived, to what extent had Aboriginals altered the landscape from its natural condition? Also, what conclusions can we draw from Aboriginal burning practices for current land management practices and the conservation of the continent’s biodiversity? Fire was the highest environmental impact technology used by Aboriginals as a highly effective land management and hunting tool. Burning the land was regarded as a ‘cleaning’ process, removing dead wood, dense brush and thorny shrubs, clearing tracks, renewing the vegetation and preventing devastating high-intensity fires.

There were many other uses: for cremation, cooking, manipulating resins, and hardening wood, especially when fashioning axes and spears. Ash was rubbed into open cut skin to produce decorative body scarring. Smoke was used to drive animals from their burrows, bats from their caves, and to deter troublesome insects, especially mosquitoes, from campsites and when fishing as it gave light and warmth. Different woods and plant parts were selected according to use – for the production of light, steam, smoke, heat or duration. As a virtually continent-wide practice burning was an activity that united Aboriginal nations, it was used for signalling, it encouraged mobility and discouraged the construction of store-houses and other permanent structures associated with settled communities. Being so central to Aboriginal life, fire connected the living with the past lives of creator-spirits. Fire sticks (firebrands) were part of the spiritual tool kit used during special fire ceremonies and rituals and to cleanse vegetation of evil spirits serving the dual purpose of making the land both productive and spiritually safe.

Firesticks

Fire was created anew in several ways: by fire-saws (thin wooden slats rubbed rapidly backwards and forwards in a wood groove filled with combustible tinder, sand sometimes being added for additional friction); fire drills (various kinds of thin wooden cylinders rolled between the hands with the point spinning and concentrating the energy into a small wooden slot with paperbark as kindling); or sometimes by striking rock like flint against ironstone to ignite kindling which included dry kangaroo dung, grass, feathers, bark etc. To avoid the effort of constantly re-making fires smouldering firebrands were maintained for long periods, sometimes as embers or long-burning materials like banksia cones, bracket fungus, rotten wood, or rolled bark.

Early European impressions of Aboriginal burning

Early European navigators, as they sailed around the coast noted in their journals the ever-present fires speculating that they marked Aboriginal camp sites or maybe signaling the presence of potential intruders. James Cook, for example, observed fires all along the east coast and the first settlers noticed that smoking firesticks were constantly carried both in the bush and as embers smouldering on patches of damp clay in the fishing canoes. Once ashore the signs of fresh burning were frequently observed and it became clear that, apart from signaling, burning was also used to drive out game, catch birds, and encourage the fresh plant growth (‘green pick’) which would both attract food animals while also promoting the growth of herbaceous tuberous plants used for food. Matthew Flinders on his circumnavigation of the continent noted that Kangaroo Island was covered with impenetrable vegetation and attributed this to the fact that it was uninhabited and therefore less frequently burned.^[14] Explorer Giles recalls his experience in rocky and extremely remote areas in the Centre:

Nevertheless the natives were about, burning, burning, ever burning . . . The fires were starting up here and there around us in fresh and narrowing circles^[4]

This method of burning produced a mosaic of burned vegetation in different stages of fire recovery while the timing and intensity of the fires could take the animal and plant communities into consideration as well as the fuel load.

. . . fires rarely extended over large areas. The effect of traditional burning regimes was to produce a series of small patches of country at different stages of recovery from fire with associated different plant and animal communities. This almost completely eliminated the risk of large scale wildfires which would have been disastrous for any group attempting to survive in a completely burnt-out area^[5]

These low-intensity ‘clean up’ fire were prescribed in the Dreaming and it opened up areas and corridors to game. Fires were rarely extinguished except at dangerous times of the year.^[20]

Firestick farming

‘Firestick farming’ is a relatively recent term coined by Australian archaeologist Rhys Jones in 1969 to describe Aboriginal land management by the use of fire to deliberately change the composition of plant and animal communities as a way of facilitating hunting and often converting scrub into grassland, thereby encouraging game species like the kangaroo.^[1] Mozaic burning acted as a firebreak and was observed on many occasions to be systematic and deliberate. Fires were less likely to threaten in the grasslands where they generally lived. Historian Blainey suggests that the rainforest on the west coast of Tasmania and the grassy valleys of its midlands, though often treated as pristine, are nothing of the sort and that impenetrable forest, parts of which have never been explored, only closed in when the Aboriginals vanished. Persistent burning has been used as an explanation for the formation of the button grass plains and sedgelands of the west coast and grass patches at the heads of north-flowing rivers.^[6] Also frequent firing encouraged the grasslands of the Darling Downs in Queensland and the fertile area of south-eastern Australia in the Murray basin. “Without those fires the grassy woodlands that occupied much of the fertile crescent of south-eastern Australia would have been scrubland or forest.”^[7] He points out that to unravel the botanical and zoological history of any strip of country in Australia is to sense the pervasive influence of fire even if agreement on fire’s exact effects is not easily reached.^[8]

Environmental impact of firestick farming

Writers like Kohen suggest that fire changed the distribution of vegetation which in turn resulted in a different set of tools, like sharp-pointed spears. As grassland emerged and megafauna became extinct there was a shift to smaller game with plants becoming a larger part of the diet.

Assembling evidence from written records and pictures

Explorer and early settler records, including illustrations of the settler Australian landscape, have been thoroughly analysed by Bill Gammage, historian and adjunct professor in the Humanities Research Centre at the Australian National University. In his 2011 multi-award-winning book The Biggest Estate on Earth^[2] Gammage paints a picture of a highly integrated system of Aboriginal land management by fire (albeit varying from one region to another), a management system that extended across the continent. Early land exploration and survey was preoccupied with locating areas with pastoral potential and many early plans depicting such open grassland have subsequently become covered with trees and scrub. Interestingly Gammage details the vegetation found by European settlers in Sydney, Brisbane, Hobart, Melbourne, Adelaide, Perth, Darwin and Canberra noting how the presence of fire-cleared land would have influenced the selection of sites for settlement. Gammage’s message is simple: landscapes seen by early European navigators and settlers arriving in Australia were not natural, but the result of a highly sophisticated burning regime enshrined in the ecological code of the Dreamtime and applied for generations across the continent, maximising access to food animals and plants. Europeans had country estates: the Aboriginal estate was the country. To quote the dust jacket: ‘Once Aboriginal people were no longer able to tend the country, it became overgrown and vulnerable to the hugely damaging fires we now experience. And what we think of as virgin bush in a national park is nothing of the kind‘ Again and again, Gammage notes, early reports mention grassy swards, sometimes with a sparse scattering of trees, comparing these areas to ‘farms without fences’ akin to the managed parkland of the country estates and deer parks of the English gentry at that time. The lack of understory in these areas he attributes to the frequent Aboriginal burns, generally using multiple small fires. He also notes that these open areas often occurred in regions that are now covered with forest or dense undergrowth. As part of this process there were abrupt transitions from dense forest and undergrowth to grassy clearings, with no apparent ecological reason, fertile soils supporting grassy swards and few trees rather than forest: the coincidence of fire-tolerant and fire-sensitive plants, he suggests, indicate careful fire management. Thinly wooded yam vine country was deliberately protected from fire. Gammage concludes that Aboriginals knew not only which plants to burn, but also the frequency and intensity of fires that would achieve desired goals. Grasslands were promoted by cool fires every 2-4 years which meant that fires at this time rarely reached the devastating extent and destructive intensity of modern fires. The imprint of burning left on the vegetation included the overtopping of rainforest by eucalypts indicating land once deliberately cleared. In the absence of Aboriginal burning that followed the decimation of the Aboriginal population by Europeans and their diseases, woody vegetation has returned. Places now named ‘grassy’ or ‘bald’ on maps are no longer so, as the burns which kept 3000 km of coast much more grassy have ceased. Different fire practices around the country are discussed by Gammage who states that ‘Most Australia was burnt about every 1-5 years depending on local conditions and purposes …’^[3] Without regular low-intensity burns land soon reverted to scrub. Fire produced land that was reborn and accessible, it was deliberately used to make grass. Burns were generally lit in summer and timed to die out by nightfall. In the Centre they were timed before rain which could be forecast from the behaviour of particular animals and here burning to flush out game was not common, hunting during fires generally being a secondary concern. Plants were also burned selectively. Gammage maintains that structural vegetation types – belts, edges, clearings, clumps – were deliberately integrated into associations which he calls ‘templates’ that made for efficient land use, offering “abundance, predictability, continuity and choice” and often linked to a natural feature in the landscape. Gammage has no doubt that Aboriginals practised a highly effective form of land management from which Europeans still have much to learn.

Present-day fire management

Devastating fires in Victoria on Black Thursday in 1851 have been attributed in part to the growth of thick scrub that had developed in the absence of Aboriginal burning. If modern infernos like those of Ash Wednesday (16 Feb. 1983) and Black Saturday (7 Feb. 2009) with their wide dispersion and extreme intensity had occurred in the past they would surely have threatened even the bush-wise Aboriginal communities. Is it possible that the land had formerly been managed to preclude them? Useful land was burned first but eventually even the most remote and montane parts of the tribal regions were fired. 2019 was our hottest and driest year on record which generated the Australia-wide 2019-2020 Black Summer bushfires.  These  forest fires burned more than 24 million hectares, directly causing 33 deaths and almost 450 more from smoke inhalation. Three out of four extreme forest fire years since states started keeping records 90 years ago have occurred since 2002. The fire season is growing, moving out of spring and summer into autumn and winter. Over the last 30 years, the areas affected by fire have expanded. Comparing satellite records from 1988–2001 to the period from 2002–2018, the annual average fire area has shot up by 350% and if the 2019–20 Black Summer fires are included, that figure soars to 800%.^[21] Regular burns are hampered by buildings, fences, hay, power and irrigation lines.

DATE	FIRE
1839 (Victoria)	Black Friday
1851     6 Feb. (Victoria)	Black Thursday
1967 1 Feb (Hobart)	Wild fire threatens Hobart
1983     16 Feb.	Ash Wednesday
2009     7 Feb.	Black Saturday
2013 19-21 Oct. (NSW)
2019-2020	Black Summer

Major widespread and intense fires since European occupation

A similar task of examining Victoria’s ‘original and natural’ condition as a result of Aboriginal firing was undertaken for Victoria in 2010 by forest ecologist Ron Hateley who was concerned that precarious assumptions were guiding current fire management. He too based his work on historical sources concluding, in part, that burning probably had little effect on forests. [Victorian fire of 1939]

Fire ecology

Fire ecologists recognise the major part played by fire for millions of years of Australian ecological history, affecting biogeochemical cycling especially through the release of climate-effecting gases and particulates, influencing the composition of biotic communities, the location of boundaries between communities, and vegetation dynamics through time. Equally clearly it has been a major factor in the evolution of fire-adapted vegetation although this would have occurred over evolutionary time-scales extending well beyond the period of human occupation. Fire can convert rainforest to eucalypt woodland and this may have occurred both in the tropics and central Tasmania.^[16] While providing essential nutrients and activating soil bacteria fire could trigger species like Yam Daisy to regenerate, other species to flower, fruit, sprout, germinate, or set seed. Some plants require fire in order to persist, especially in eucalypt-dominated humid but drought-prone regions while species typical of the more consistently humid east and northeastern coast, are fire sensitive. Grassland, woodland and sclerophyll are adapted to fire. Woodland and forests can burn regularly without long-term decline in fauna and a regime of one burn every three years produces a sustainable macropod population – mosaic burning is very effective. Frequent burning of wet sclerophyll will change the species composition. Kohen points out that even if firestick farming was fairly widespread and its impact substantial, its use was probably confined to the late Holocene with climate the more important causal factor in vegetational change before this time.^[17] Tasmanians used fire to open up the landscape and this probably occurred about 4,000 BP surprisingly this seems to be about the same time as a substantial change on the mainland.^[17]

Charcoal analysis

Using the completely different approach of pollen analysis and evidence of past fires from charcoal presence in core samples has produced completely different conclusions from those of Gammage have been drawn. Clarke, in 1993 stated:

Aborigines neither created nor maintained vast areas of grassland, although their burning may have been responsible for the continuation of patches of grassland or woodland within larger forested regions. Climate has been and is far more important than fire in determining the distribution of Australian vegetation, but Aboriginal burning might have effected the rate of vegetational change^[10]

More recently researchers have used radiocarbon datings from 286 archaeological sites in arid Australia (AustArch1) to assess human activity and population history through time using the deposition of charcoal carbon as a measure of burning. These studies have concluded that there was no distinct change in fire regime corresponding to the arrival of humans in Australia at 50 ±10 ka and no correlation between the archaeological evidence of increased human activity during the past 40 ka and the history of biomass burning. However, changes in biomass burning in the last 200 years may have been exacerbated or influenced by humans.^[9] Other workers have come to similar conclusions.^[19] The situation is difficult to assess as archaeological evidence has indicated that different lifestyles and technology were adopted in different regions of Australia at different times, possibly as a result of multiple waves of occupation. Accordingly burning practices probably varied across the continent depending on local conditions. It is also extremely difficult to determine the relative influences of climate and Aboriginal burning on ecological change, as well as comparing the frequency and intensity of anthropogenic burn and those arising from natural causes like lightning strikes. However, charcoal sampling and molecular phylogenetic analysis seems to have put to rest the view that Aboriginal burning triggered the evolutionary diversification of fire-adapted species: this had happened long before the arrival of humans in Sahul.^[11]  

Commentary & sustainability analysis

There can be little doubt that Aboriginal use of fire has altered natural landscapes although the possible influence on early magafauna is also likely to have been of some consequence. In general it seems to have been vegetation that was poor in animal and plant food species that was burned rather than rainforest or riparian areas. Use of fire by indigenous American Indians is also considered a factor in the character of the North American grasslands of the Great Plains.

Though the use of firestick farming is now generally accepted there is a divergent and sometimes acrimonious disparity of views concerning the extent to which its consequences were known and planned, the places of major use, the extent to which it has been used over the period of c.55,000 years of Aboriginal occupation, together posing the key question of the scale of anthropogenic and climatic landscape change that occurred over this time period.

We still cannot give a very clear answer to this question. In a summary review of the impact of Aboriginal burning on the Australian biota David Bowman concluded that:

. . . there is a large body of circumstantial evidence which suggests that altered fire regimes following the cessation of Aboriginal burning have resulted in substantial changes in the range and demographic structure of many vegetation types, such as rain forest, with corresponding changes in animal populations.^[13]

And again in 2011 an eminent team of ecologists and researchers concluded:

. . . fire in Australasia predominantly reflects climate, with colder periods characterised by less and warmer intervals by more biomass burning . . . There is no distinct change in fire regime corresponding to the arrival of humans in Australia at 50 +- 10 ka and no correlation between archaeological evidence of increased human activity durung the past 40 ka and the history of biomass burning.^[15]

Anthropogenic fire has the capacity to shape plant communities as ‘unnatural’ regular firing can lead to the extinction of species that are unable to reproduce effectively when there is an increased frequency of burns. This in turn influences the animal populations to produce a “trophic cascade”. What possibly occurred in Pleistocene Australia was the fragmentation of woodlands and forests and spread of grasses, especially Triodia, as a result of anthropogenic burning. There was then possibly a further trophic collapse when, with the arrival of Europeans, anthropogenic burning was reduced, leading to the decline of small-to-medium size mammal populations. However, the persuasiveness of this thesis and the way in which anthropogenic fire has influenced these processes remain a matter for research.^[12]

What part did Aborigines play in the contemporary composition and distribution of plants and animals? How have burning practices changed over time either in their intensity or method? As always, individual areas may have been treated differently at different times.

Interpreting charcoal data is contentious. High charcoal might indicate high anthropogenic burning – but then without human burning when fires occur they are very intense and can leave good charcoal remains, which is an indication of a lack of human burning. Perhaps fire-adapted vegetation remains essentially unchanged under an increasaed anthropogenic firing regime? Frequent firing can add to erosion and subsequent sedimentation from hillsides.

First published on the internet – 1 March 2019

4 July 2023 – minor edit