Aboriginal hunting buffers climate-driven fire-size variability in Australia’s spinifex grasslands

Abstract

Across diverse ecosystems, greater climatic variability tends to increase wildfire size, particularly in Australia, where alternating wet-dry cycles increase vegetation growth, only to leave a dry overgrown landscape highly susceptible to fire spread. Aboriginal Australian hunting fires have been hypothesized to buffer such variability, mitigating mortality on small-mammal populations, which have suffered declines and extinctions in the arid zone coincident with Aboriginal depopulation. We test the hypothesis that the relationship between climate and fire size is buffered through the maintenance of an anthropogenic, fine-grained fire regime by comparing the effect of climatic variability on landscapes dominated by Martu Aboriginal hunting fires with those dominated by lightning fires. We show that Aboriginal fires are smaller, more tightly clustered, and remain small even when climate variation causes huge fires in the lightning region. As these effects likely benefit threatened small-mammal species, Aboriginal hunters should be considered trophic facilitators, and policies aimed at reducing the risk of large fires should promote land-management strategies consistent with Aboriginal burning regimes.climate change | patch mosaic burning | trophic facilitation

Managing the human component of fire regimes: lessons from Africa

“…The current high rural densities of people are therefore probably temporary, and likely to reduce within the next 50-100 years. Data presented here, and lessons from Australia and other systems where rural areas have become depopulated [68,89], suggest that the total area burned is likely to increase (figure 3), as will the extent of large, intense, extreme fire events (figure 7) as people remove their influence on fuels and the season of ignition in these grassy fire regimes. However, if this depopulation comes together with the expansion of large-scale agriculture on the continent then both the landscapes and the fire regimes of Africa will be fundamentally transformed, perhaps converging on the 'human pyrome' of figure 2.…”

“…However, human intervention in these fire regimes is considered necessary from three main (and unfortunately not necessarily complementary) standpoints-each operating at different socio-political levels. At a local level, the focus is on sustaining livelihoods-lighting fires to clear/prepare/protect fields, to provide forage, to attract game and to control vegetation structure (tree/grass ratios) [52,68,70,71]. At national levels, conserving biodiversity is the main goal, as well as preventing loss of life/infrastructure, although ensuring the sustainability of people's livelihoods is also an important concern [49,62,70,72].…”

“…If anything, therefore, a negative rather than a positive relationship between high temperatures and total area burned is expected in grassy systems [67]. Moreover, the strong negative impact of people on fuels buffers most parts of Africa from inter-annual variability in climate-with high variations in area burned only possible in sparsely populated landscapes [29,68].…”

Small islands, valuable insights: systems of customary resource use and resilience to climate change in the Pacific

“…For example, in shifting agriculture systems, the process of succession is manipulated as ecological communities and landscapes are managed through temporary small-scale clearings and, in many cases, controlled fires. There is growing evidence that some customary resource management systems in the Pacific can play a key role in maintaining ecological integrity in the context of disturbance (Ticktin et al 2006, Bird et al 2012, Trauernicht et al 2013. Customary resource management systems have also been recognized as key to building adaptive capacity in small Pacific Islands (Campbell 2006, Barnett and Campbell 2010, Vaughan and Vitousek 2013, but they continue to be modified under rapidly changing social, economic, and ecological contexts (Cinner and Aswani 2007, Brewer et al 2012, Lauer et al 2012).…”

“…A key component of biocultural diversity is the ILK. The localized and temporal depth of understanding in ILK systems is the basis for abundant and growing literature that clearly demonstrates the links between ILK and sustainable resource use (e.g., Bird et al 2012, Schmidt and Ticktin 2012, including in Pacific Islands (e.g., Johannes 2002, Thaman 2008, Friedlander et al 2013. In the Pacific Islands, ILK systems have also been shown to build adaptive capacity to social and environmental change (Campbell 2006, Barnett and Campbell 2010, Lauer et al 2012 and to improve understanding of the social-ecological effects of climate change (e.g., Berkes 2009, Lauer et al 2012, Rudiak-Gould 2014.…”