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CONFERENCE PROCEEDINGSAustralian Bushfire Conference, Albury, July 1999 |
copyright 1999 |
The importance of biodiversity as a goal of environmental management is increasingly accepted in the community; but what is our definition of Australian biodiversity? In its ideal sense we take it mean that diversity of organisms and ecosystems which existed when Europeans entered the Australian continent, although from that we must now subtract those which have become extinct in the last 200 years. The ecosystems we took over had a long previous history - they had been shaped by the activities of Aboriginal people for many thousands of years. Edward Curr, a very perceptive pioneer settler in Victoria, described the Aborigine thus: 'living principally on wild roots and animals, he tilled his land and cultivated his pastures with fire' (Curr 1883).
The knowledge of how to make, keep and use fire was part of the luggage that the Australian Aborigines brought with them into this continent at least 40,000 years ago. As they penetrated further south, they found a vegetation which became increasingly unfamiliar, but, (to put it simply) over many thousands of years they learned how to apply fire to it, so that when the Europeans arrived a mere 200 years ago, they were getting a good sustainable living from both animals and plants.
In 'Fire and the Australian Biota', Phyllis Nicholson (1981) made the following points which she said 'should be emphasised when the effects of Aboriginal fire are being assessed'
Today these points seem hardly controversial, but their implications, not recognised in other chapters of Fire and the Australian Biota, are still not considered by many authors. In the new Introductory volume to the Flora of Australia, (1999), Aborigines rate only an inadequate passing mention; the role of Aboriginal fire in the evolution of the Australian flora is almost totally ignored.
Bowman (1998) in a recent comprehensive review,has however recognised the importance of the long history of Aboriginal burning, and has called the impact of Aboriginal burning 'one of the most complex and contentious issues in Australian ecology', adding
'This issue is not only important for the development of a comprehensive understanding of the dynamics and evolution of the Australian biota, but is central to the formulation of appropriate strategies for the conservation of the nation's biota'
He concludes that ' fire was a powerful tool that Aborigines used 'systematically and purposefully over the landscape' (P.390) and that there is 'little doubt that Aboriginal burning was skilful and was central to the maintenance of the landscapes colonised by Europeans in the 19th century(p. 404)
If fire was used 'systematically and purposefully' to what system and what purpose was it used ? Anthropological accounts of burning are biased towards its role as a hunting tool - 'hunting, path-clearing and communication' (ABC Science News 1999), but the importance of vegetable food in the diet is usually ignored. Another fact that is sometimes ignored is the dependence of the hunted animals on the existence of appropriate vegetation.
When Europeans arrived in Victoria, and before the spread of introduced disease, the reports described the Aborigines as healthy and well-fed. - 'strong and athletic, often 6 ft tall, very intelligent and quick in their perceptions, with exceptional eyesight and particularly fine teeth' (Gellibrand in Bride,1898 p.31). Eyre, (1845, pp. 252, 254 ) said 'in almost every part of the continent...I have found that the natives could usually, in 3 or 4 hours, procure as much food as would last for the day, and that without fatigue or labour'
They had inhabited the land for thousands of generations, had endured major climate changes, yet they were still living well. Both animal and plant food was abundant, (Campbell 1987, p.96; Goodwin 1854) and plant food was at an estimate about 50% of the diet (Winter in Bride 1898 p.395; Latz 1995 p.27) . When hunting was unsuccessful it was the fall-back food. George Augustus Robinson, the Protector of Aborigines, in 1840 noted that the basalt plain known as Spring Plains was covered with millions of Murnong, Microseris lanceolata, the tubers of which were a major staple food ( Clark 1998 Vol 1, p.135; Gott 1983 ). Major Mitchell in 1836 described the view south and east from the Grampians as ' a vast extent of open downs ... quite yellow with Murnong' and 'natives spread over the field, digging for roots' (Mitchell, T.L. 1839 p.272) The inescapable conclusion must be that the resources were exploited in such a way that their abundance had been maintained.
What were the plant food resources ? In southeastern Australia it was 'roots' in the broad sense which were the staple foods. ' They depend for food almost entirely on animals and roots' (Dawson 1881; Winter in Bride.1898 ;. Gott 1982; Clarke 1985). In Victoria, seeds were hardly used at all, although they became staples in the arid regions of Australia. Roots have the advantage of being available year round, unlike seeds and fruits which are seasonal. Of the 940 species recorded as used for food in Victoria, 296 (32% )were used for their underground parts (Gott 1997, .database). Robinson in 1840 described women 'spread over the plain as far as I could see them , collecting [roots]--- each had a load as much as she could carry' (Clark 1998 ).
In the lowland climate of southern Australia, the major period of stress for small perennial herbaceous plants is high summer, when water becomes scarce. They die back and rely on food and water stored in underground organs, on "roots" in the broad sense for survival and to provide for new growth when temperatures fall and the autumn rains arrive. They produce leaves during the autumn and winter, flower in the spring and early summer, seed and die back in high summer. Although tolerant of some shade, they thrive best in open forest and on the plains.
The plains areas of Victoria were a major source of tuberous roots. Taking either the general checklist for the whole of the Western Victorian Plains, containing 550 species, (Willis 1964 ) or the list for the Keilor plains area (Sutton 1916) , approximately 20% of the plants are actually recorded in the literature as used by Koories for food, and half of these come from underground organs. Robinson, in 1841, wrote ' they [the Aborigines] burn the grass, the better to see these roots, but this burning is a fault charged against them by squatters' ( Clark 1998 )
The early European descriptions of the dry sclerophyll forest emphasise its open nature, 'where a man might gallop without impediment and see whole miles before him' The effect of the cessation of the Aboriginal burning regimes was noted by many authors.
'the omission of the annual periodical burning by natives of the grass and young saplings has already produced in the open forest lands nearest to Sydney thick forests of young trees... Kangaroos are no longer to be seen there, the grass is choked by underwood; neither are there natives to burn the grass, nor is fire longer desirable among the fences of the settlers' (Mitchell 1848)
Walker (1898) in Tasmania; and Howitt (1890) in Victoria, noted the same effects. Lunt (1998) has examined the history of land use on the Bellarine Peninsula, southern Victoria. In the early 1800s there were less than 20 trees ha-1, that area now has 3000 trees ha-1.
We know that for many thousands of years these areas had been subject to burning, but there is little detail in the early observations by Europeans which enable us to construct the burning regimes applied by the Aborigines. Edward Curr was of the opinion that there was an average interval of 3-5 years between fires (Curr 1883). In 1840 Stokes made the following observation in Western Australia :
'On our way we met a party of natives engaged in burning the bush, which they do in sections every year. The dexterity with which they manage so proverbially a dangerous agent as fire is indeed astonishing. Those to whom this duty is especially entrusted, and who guide or stop the running flame, are armed with large green boughs, with which, if it moves in the wrong direction, they beat it out. ' (Stokes 1846)
William Thomas, Assistant Protector of Aborigines in the Melbourne region, in March 1840 observed an old Aborigine who, despite efforts to discourage him, persisted in setting fire in an area of thick scrub with grass beneath. After a time the old man stopped because he said 'he had accomplished his purpose' Other Aborigines were also burning at this time, and the settlers wanted to stop them. Donald Thomson, (1949) in Arnhemland, said burning 'is not a random business ... [it is] directed by the old men of the tribe, or by others who have an hereditary right.' So we have from these early observations deliberate and directed burning, patch burning, and possible intervals of 3-5 years in late summer in southern Victoria,
In discussing the responses of open forests to fire regimes, Christensen and co-workers (1981) have pointed out that vegetation is adapted to particular patterns of fire involving frequency of burning, fire intensity and season of occurrence. If one wishes to protect small tuberous perennials from the effects of fire, late summer, just before the autumn rains, is the time to burn. They are safely underground as tubers.
Christensen and co-workers (1981) cite the example that Autumn fires favor regeneration of herbaceous species (Baird 1977). The Ash Wednesday fires of February 1983 at Anglesea, Vic. occurred at just this time, amd in the following spring there was a phenomenal flowering of tuberous perennials. In the unburnt areas the flowering was by contrast quite sparse.
The results of firing were the return of nutrients to the soil and the removal of shading, creating clear areas favourable to seed germination and the regeneration of plants from underground organs, and the new green growth also attracted grazing animals. A recent 10 year study of recovery from this fire by Wark (1996) showed that most of the species which flowered in the first year after the fire were herbaceous, and that 'the early herbaceous phase declined in cover and density of flowering during the second and third years as shrub and canopy cover increased'. Grazing reduced the frequency and density of herbaceous species in the early years after the fire. Species richness decreased after the third year; the number of herbaceous species present decreased by year 10 to about 40% of the year1-3 level. The Aborigines were depending on these herbaceous species - notably Liliaceae, Orchidaceae, Microseris lanceolata, for food, so that burning at 3-year intervals , the maintenance of the forest in an arrested stage of fire recovery, would have ensured optimal supply. Without referring to Aboriginal burning, Christensen and co-workers (1981) state that 'there is a natural maximum fire frequency of 3-4 years in dry sclerophyll forests'.
A similar picture emerges from a grassland study by Morgan (1998) 'If seedling recruitment events are to be optimised for the herbaceous dicotyledons which characterise this community, disturbance to the canopy is required at intervals of 1-3 years'.
Lunt (1998 )suggests intervals of burning of Themeda grassland of 3-4 years to maintain species diversity. He further considers that fires at something like 5 -year intervals would help to maintain open woodland and adds that 'no details of Aboriginal burning regimes are available'.
It is my contention that embedded in these communities is an evolutionary history of burning at the intervals and seasons required to maintain the open woodlands and species diversity found before European alteration of the landscape.
An interesting study on the conservation of the New Holland mouse in south Gippsland (Quin et al. 1996) recommends the following: 'a burning regime in the heathy woodlands which is appropriate ... small scale fires implemented at intervals which produce a mosaic of habitats with differing ages '. This surely represents the Aboriginal burning history of the area. burning on a microscale, of small selected patches of desirable plants, rather than more extensive areas, has been recorded (Gott, in press).
Latz (1995) has shown that important food plants in Central Australia act as 'fireweeds',- the yields peak after fire, but decline rapidly in successive years. Solanum vescum, one of the Kangaroo Apples, was an important fruit for the Kurnai in Gippsland. In the first year after a fire, it is abundant, arising from longheld seed stores in the soil, but it thrives for only a short period, and regular burning is necessary for continued fruit production.
I must emphasise that these studies come from southern Victoria. Burning practices would have varied according to climate and the nature of the vegetation (Kohen 1995). Frequency and timing of fires in the tropical north would have been quite different (Bell 1988) and Ashton's long series of studies of Eucalyptus regnans forest at Wallaby Creek would indicate that deliberate firing of wet sclerophyll was highly unlikely (Ashton 1976).
Another factor of Aboriginal management which I have not mentioned was the continual digging of the women in the collecting of roots. The benefits of this cultivation of the soil are obvious, as well as the promotive effect of thinning out dense patches and clumps of desired food plants. (Gott 1982, 1993).
Much Australian vegetation has been irreversibly changed from that of pre-European times, and not only by the cessation of Aboriginal burning. Yet there are some areas which by accident have escaped major change. Some roadsides and railway reserves were regularly burned, and if they escaped recent treatment with herbicides, they have often preserved diversity. Firing can be an invitation to the invasion of introduced weeds and we can only hope to conserve the original diversity in selected areas. The timing of fuel reduction burns is vital - too many of them take no account of the ground flora, and if they are not carried out when tuberous ground flora are dormant, as was the case with Aboriginal firing, they can reduce the biodiversity. We need to take account of Aboriginal management of the ecosystems and its long evolutionary history if we are to succeed.in our own management.
Flora of Australia, Volume 1, Introduction, 2nd edn (1999).
Published by School of Environmental & Information Sciences Charles Sturt University