Pre-European Fire Regimes in Australian Ecosystems (original) (raw)
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The extent of prehistoric human impact on the environment is a contentious topic in various palaeo-environmental sciences. The long history of humans in Australia and its extensive fire-prone biota makes this continent a key research area for better characterization of prehistoric human-fire interactions. Here we use statistically robust cross-correlation of archaeological radiocarbon data (n=4,102 ages from 1,616 sites) and a new synthesis of charcoal records (n=155 sites) to test for any relationship between people and fire over the last 20,000 years at continental and regional (25-45oS) scales. We find that the statistical correlation between the two datasets is weak at both spatial scales, with short-lived synchronous responses only in the terminal Pleistocene-Holocene transition, at the onset of the mid-Holocene climatic optimum (~10-7ka) and during significant transitions of El Niño Southern Oscillation (~5-4ka and 1.2-0.8ka). One interpretation of this is that Aboriginal populations were implementing ‘fire-stick farming’ only intermittently during periods of societal stress resulting from climatic variability. However, the synchronicity of the correlations with climate changes, along with the low populations through much of this time, suggests both datasets were independently responding to external climatic forcing. Under either scenario, a lack of significant change in the charcoal record implies that there were no long-lasting impacts to the environmental biota, and macro-scale palaeoenvironmental records prior to European colonisation largely reflect responses to non-human influences. While we do not discount the possibility of systematic or deliberate manipulation of fire regimes at local spatial scales, we conclude that human control of fire by prehistoric people in Australia is not evident at broad landscape levels. This conclusion contradicts persistent suggestions of Australian-wide land management and the pervasiveness of the impacts of ‘fire-stick farming’.
Indigenous impacts on north Australian savanna fire regimes over the Holocene
Scientific Reports, 2021
Fire is an essential component of tropical savannas, driving key ecological feedbacks and functions. Indigenous manipulation of fire has been practiced for tens of millennia in Australian savannas, and there is a renewed interest in understanding the effects of anthropogenic burning on savanna systems. However, separating the impacts of natural and human fire regimes on millennial timescales remains difficult. Here we show using palynological and isotope geochemical proxy records from a rare permanent water body in Northern Australia that vegetation, climate, and fire dynamics were intimately linked over the early to mid-Holocene. As the El Niño/Southern Oscillation (ENSO) intensified during the late Holocene, a decoupling occurred between fire intensity and frequency, landscape vegetation, and the source of vegetation burnt. We infer from this decoupling, that indigenous fire management began or intensified at around 3 cal kyr BP, possibly as a response to ENSO related climate vari...
2021
Indigenous land use and climate have shaped fire regimes in southeast Australia during the Holocene, although their relative influence remains unclear. The archaeologically attested mid-Holocene decline in land-use intensity on the Furneaux Group islands (FGI) relative to mainland Tasmanian and SE Australia presents a natural experiment to identify the roles of climate and anthropogenic land use. We reconstruct two key facets of regional fire regimes, biomass (vegetation) burned (BB) and recurrence rate of fire episodes (RRFE), by using total charcoal influx and charcoal peaks in palaeoecological records, respectively. Our results suggest climate-driven biomass accumulation and dryness-controlled BB across southeast Australia during the Holocene. Insights from the FGI suggest people elevated the recurrence rate of fire episodes through frequent cultural burning during the early Holocene and reduction in recurrent Indigenous cultural burning during the mid–late Holocene led to increa...
Fire and vegetation change during the Early Pleistocene in southeastern Australia
Journal of Quaternary Science, 2012
Early Pleistocene vegetation in upland southeastern Australia included diverse rainforests and sclerophyll forests, which alternated on precessional timescales. The nature and timing of transitions between these biomes, and the role of fire in maintaining or driving transitions between them, are uncertain. Here we present a highresolution pollen record from Stony Creek Basin, a small Early Pleistocene palaeolake in southeastern Australia. The pollen record documents a pattern of vegetation change, over ca. 10 ka at ca. 1590-1600 ka, between sclerophyll forests, dominated by Eucalyptus, Callitris (Cupressaceae) or Casuarinaceae, and rainforests dominated by either angiosperms or conifers of the family Podocarpaceae. Transitions between these biomes typically occurred within ca. 1-2 ka. The associated charcoal record suggests that greatest biomass combustion occurred when local vegetation was dominated by Eucalyptus, and the least biomass combustion occurred when local vegetation was dominated by Podocarpaceae. However, local fires burnt in both sclerophyll and angiosperm-dominated rainforest vegetation, at least once every several centuries. Fire was very rare (less than about one fire per millennium) only when the local vegetation was rainforest dominated by Podocarpaceae. This suggests that fire was an irregular presence in both sclerophyll-and angiosperm-dominated rainforest biomes during the late Neogene, though was largely absent in Podocarpaceae-dominated rainforests.
Aboriginal fires in monsoonal Australia from historical accounts
Journal of Biogeography, 2002
Aim Traditional management of fire in the world's savannas is of vital interest for contemporary management. This paper reviews the nineteenth century literature on Aboriginal application of fire in the Northern Territory of northern Australia, and relates the other studies of the historical record for the whole savanna region of northern Australia. The aim is to provide a comprehensive picture of historical traditional fire practices.
Journal of Quaternary Science, 2012
Early Pleistocene vegetation in upland southeastern Australia included diverse rainforests and sclerophyll forests, which alternated on precessional timescales. The nature and timing of transitions between these biomes, and the role of fire in maintaining or driving transitions between them, are uncertain. Here we present a highresolution pollen record from Stony Creek Basin, a small Early Pleistocene palaeolake in southeastern Australia. The pollen record documents a pattern of vegetation change, over ca. 10 ka at ca. 1590-1600 ka, between sclerophyll forests, dominated by Eucalyptus, Callitris (Cupressaceae) or Casuarinaceae, and rainforests dominated by either angiosperms or conifers of the family Podocarpaceae. Transitions between these biomes typically occurred within ca. 1-2 ka. The associated charcoal record suggests that greatest biomass combustion occurred when local vegetation was dominated by Eucalyptus, and the least biomass combustion occurred when local vegetation was dominated by Podocarpaceae. However, local fires burnt in both sclerophyll and angiosperm-dominated rainforest vegetation, at least once every several centuries. Fire was very rare (less than about one fire per millennium) only when the local vegetation was rainforest dominated by Podocarpaceae. This suggests that fire was an irregular presence in both sclerophyll-and angiosperm-dominated rainforest biomes during the late Neogene, though was largely absent in Podocarpaceae-dominated rainforests.
Rainforests, Agriculture and Aboriginal Fire-Regimes in Wet Tropical Queensland, Australia
Australian Geographical Studies, 2000
This paper challenges the hypothesis that Aboriginal fire-regimes in the coastal wet tropics of north Queensland have been responsible for significant rainforest decline in the past, and rejects the narrative that recent rainforest expansion is the result of the disappearance of Aboriginal people and their fire practices from the area. Mapping of vegetation in the Mossman district in c. 1890 from surveyors’ plans, and in 1945 and 1991 from aerial photography demonstrates that the expansion of rainforest since 1945 represents a recovery following extensive rainforest destruction associated with sugar cane cultivation in the first 70 years of European occupation. Kuku-Yalanji Aboriginal people continued to occupy their traditional lands, and participated in the sugar industry, throughout this period. They adapted their fire management practices to the changed economic and social circumstances. Management of fire by the Kuku-Yalanji people prior to European occupation ensured the presence of extensive rainforest cover, whilst also providing access to fire-prone forests and their cultural resources.
Reconstructing Aboriginal impacts on Australian forests
Proceedings of the 6th National Conference of the Australian Forest History Society
This paper presents archaeological perspectives on pre-European human impacts on Australian forests. Major questions, of interest to conservation and forestry also, are (i) how were forests used by hunting and gathering people? and (ii) to what extent did they manage forests by fire? Ethnographic and historic records attest to the Aboriginal use of fire in forests to control understoreys and manage food plants and animals. Opinions vary widely, however, on the ecological significance of past hunter-gatherer fire management and the cultural significance of evidence for past fires such as charcoal counts in pollen cores. This paper explores the potential clues to anthropogenic ecological changes to be found in the stratified archaeological and palaeontological records from limestone cave and rock shelter floor deposits in the Leeuwin-Naturaliste Region of south-western Australia. Comparison of this evidence with regional evidence for climatic change helps show whether local changes in flora and fauna were the result of changes in human activity or climate. Other clues derive from the distribution of artefacts as identified in area survey across vegetation zones. The various lines of evidence involve different geographic and temporal scales. Understanding and accounting for differences in scale will be critical in the future development of these methods in archaeology and palaeo-ecology.
Proceedings of the Royal Society B: Biological Sciences, 2013
Climate and fire are the key environmental factors that shape the distribution and demography of plant populations in Australia. Because of limited palaeoecological records in this arid continent, however, it is unclear as to which factor impacted vegetation more strongly, and what were the roles of fire regime changes owing to human activity and megafaunal extinction (since ca 50 kya). To address these questions, we analysed historical genetic, demographic and distributional changes in a widespread conifer species complex that paradoxically grows in fire-prone regions, yet is very sensitive to fire. Genetic demographic analysis showed that the arid populations experienced strong bottlenecks, consistent with range contractions during the Last Glacial Maximum (ca 20 kya) predicted by species distribution models. In southern temperate regions, the population sizes were estimated to have been mostly stable, followed by some expansion coinciding with climate amelioration at the end of the last glacial period. By contrast, in the flammable tropical savannahs, where fire risk is the highest, demographic analysis failed to detect significant population bottlenecks. Collectively, these results suggest that the impact of climate change overwhelmed any modifications to fire regimes by Aboriginal landscape burning and megafaunal extinction, a finding that probably also applies to other fire-prone vegetation across Australia.
Journal of Biogeography, 2002
Aim To compare ®re behaviour and ®re management practice at a site managed continuously by traditional Aboriginal owners with other sites in tropical northern Australia, including the nearby Kakadu National Park, and relate those observations to indicators of landscape condition. Location Dukaladjarranj, a clan estate in north-central Arnhem Land, in the seasonal tropics of northern Australia. The site abuts a vast sandstone plateau that is an internationally recognized centre of plant and animal biodiversity. Methods Ecological assessments included: (1) mapping of the resource base of the estate from both traditional and ecological perspectives; (2) aerial survey of the extent of burning, distribution of the ®re-sensitive native pine Callitris intratropica, rock habitats, and a range of macropod and other fauna resources; (3) fauna inventory; (4) detailed ecological assessment of the status of ®re-sensitive vegetation; and (5) empirical assessment of the intensities of experimental ®res. Ethnographic information concerning traditional ®re management practice was documented in interviews with senior custodians. Results Experimental ®res lit during the study were of low intensity compared with late dry season ®res reported elsewhere, despite weather conditions favouring rapid combustion. In contrast to other parts of the savanna, fuel loads comprised mostly leaf litter and little grass. We found that (i) a large proportion of the estate had been burned during the year of the study (ii) burned sites attracted important animal food resources such as large macropods (iii) important plant foods remained abundant (iv) well represented in the landscape were ®re sensitive vegetation types (e.g. Callitris intratropica Baker & Smith woodlands) and slow growing sandstone`heath' typically dominated by myrtaceaous and proteaceous shrubs (v) diversity of vertebrate fauna was high, including rare or range-restricted species (vi) exotic plants were all but absent. Traditional practice includes regular, smaller ®res, lit throughout the year, and cooperation with neighbouring clans in planning and implementing burning regimes. Main conclusions We attribute the ecological integrity of the site to continued human occupation and maintenance of traditional ®re management practice, which suppresses