- While research is still mixed on whether diverse fire patterns promote biodiversity, a new study suggests that practices under active Indigenous stewardship can do so.
- The study draws a reference to Aboriginal Martu peoples in the northwest deserts of Australia, who have an ancient history of fire practices and experience used to manage the land and hunt.
- Martu fire patterns and post-fire stages help influence plant richness and diversity in arid landscapes dominated by spinifex, say the authors say.
- Indigenous burning practices are often carried out during cooler times of the year, such as in the winter for the Martu, which resulted results in slow, cool, and low-intensity fires that reduced the potential for fire burning out of control and into becoming wildfires.
For generations, Aboriginal Martu people in the northwestern deserts of Australia managed their ancestral lands and shaped their landscapes using fire. Burning small, frequent and low-intensity fires in diverse fire patterns, they promoted the growth of an array of species in what is often called “pyrodiversity.”
While research is still mixed on whether pyrodiversity helps promote biodiversity, a recent study found evidence that pyrodiversity practices under active Indigenous stewardship can do so, drawing a reference from findings in Martu communities.
These fire practices, also known as cultural burning, first began as a First Nations practice to improve the health of the land and their people. For more than 60,000 years, communities used it to manage land, plants and animals and also to hunt.
According to traditional beliefs, there was a time when the Martu people didn’t have fire. It was always spotted in the distance, but when the Martu would hurry to reach it, they found nothing.
“The blue-tongued lizard would hide the fire from them and they’d be cold,” Kirriwirri (Mac Gardner), a Martu elder, explained in a documentary, “but the chicken hawk stole it away and gave it to the Martu who became warm, full and fat. And so Martu life with fire begins.”
Since then, Martu people, the traditional owners still stewarding this vast arid landscape, held on to their ancient fire knowledge and experience, which included knowledge of the intensity, extent and placement of fires. Their land ranges from patches that are recently burnt to those that are several decades old. It also ranges from patches that are burnt a couple of times to those that are burnt several times.
“By creating landscapes that have a diversity of historical fire patterns across time and space, Martu fire practitioners increase plant richness and diversity,” said Leanne Greenwood, lead author of the study and an ecologist from Charles Sturt University.
Over millennia, this Indigenous traditional management shaped the fire patterns of many of Australia’s ecosystems for generations that exist today.
“It is becoming more and more obvious, with substantial scientific evidence support, that the displacement of Indigenous people and their burning practices has contributed to drastic changes in fire patterns and has contributed to the decline of species from landscapes,” she told Mongabay. Supporting Indigenous people in achieving their aspirations in cultural burning and re-creating the diverse fire mosaics is important for promoting and maintaining plant diversity in fire-prone ecosystems, she said.
Fire and Earth
The majority of arid Martu landscapes are dominated by spinifex (Triodia spp.), a type of grass with a sharp spine that out-competes other plant species in long unburnt areas. In this case, burning plays a crucial role in the ecosystem by reducing the grass to its roots and enhancing the growth of subshrubs, herbs and other edible species such as bush tomatoes (Solanum spp.), Scaevola parvifolia and wollybutt grass (Eragrostis eriopoda) that are significant to Martu communities for their diets, medicine or culture.
“It’s not dead after it’s burnt,” explained Waka Taylor, a Martu elder. “The burnt ground can rejuvenate with all different types of bush foods.”
Martu communities recognize five postfire successional stages: the nyurnma for recently burnt patches, waru waru for when plants resprout following rain, nyukura for when plants mature and produce flowers and fruit, manguu for when the spinifex dominates the landscape andcan carry fire and, finally, kunarka for when mounds of spinifex grow old.
When spinifex, known to be drought-tolerant, regains dominance in later-successional stages, many small-statured species start to disappear.
“The taller and longer-lived plants, like wattles and grevilleas, often resprout after fires and can persist in older patches alongside spinifex,” Greenwood told Mongabay.
According to the study, it is through cultural burning and different combinations of small, frequent, low-intensity fire patterns that an ecosystem can support different plant needs that are important for small, short-lived species. However, the authors say that maximizing pyrodiversity without acknowledging the historical extent and levels of fire used in pyrodiverse landscapes maintained by Indigenous peoples may not result in appropriate fire management and could have adverse effects.
Some studies do not support the hypothesis that pyrodiversity promotes biodiversity, at least in certain contexts or relating to certain species. A 2018 study exploring relationships between termites, habitat and fire found that fire did not enhance termite species richness in semiarid Australia. While the history and intensity of fire use affected the prevalence of certain termite habitats, it didn’t affect the species’ richness, per say.
According to the recent study on Martu fire stewardship, visible and invisible fire patterns also play a role in plant richness and diversity. The visible fire patterns include patterns in landscapes visible enough to acknowledge what has been burnt recently and what has long been unburnt. This played a more significant role in plant diversity. The invisible fire pattern is what cannot be seen with the naked eye, which includes the number of times the patches have been burnt.
“The invisible fire mosaic or the diversity in how many times the patches had been burnt was not important for all the plant groups that we investigated, but high fire frequency diversity promoted higher diversity of those smaller short-lived herbaceous plant species,” Greenwood told Mongabay.
Holding on to the knowledge
As Martu communities have a long history of extensive fire experience and burning in Australia, the study also aimed to find evidence of the importance of burning practices actively stewarded by Indigenous peoples in the face of historical suppression.
Clay Trauernicht from the University of Hawaii at Mānoa, who was not involved in the study, said ecological changes in landscape due to a decline of Indigenous cultural burning did not arise from suppressing Indigenous burning itself. Rather, he explained, they are a result of colonial events and political and economic systems that have suppressed Indigenous peoples and their cultures.
“This is why fire has emerged as such a powerful tool through which Indigenous people are not just reasserting their relationship with the land but showing how that relationship underpins all of our health and safety,” he told Mongabay. Between 2001 and 2020, there were substantially more fires in almost all bioregions in Australia than between 1981 and 2000.
With fires, risks are inevitable, which are likely to be intensified with cultural burnings. Trauernicht said sometimes conditions change, such as sudden gusts of wind, making fires prone to burning out of control, damaging land and property. Winds are among the least predictable weather conditions driving this risk.
“Sometimes desired ecological conditions are difficult to achieve under prescribed conditions, such as removing woody species from open savanna or plains,” he said.
Greenwood, who has observed Martu cultural burnings in the northwestern deserts and that of the Dja Dja Wurrung people in mountainous states of southeast Australia, said she didn’t think their fires posed a risk of turning into uncontrolled wildfires. Indigenous fire practitioners have in-depth knowledge of their landscapes and generations of observation and practice to guide their burning practices, she told Mongabay. Although accidents can happen, Indigenous burning practices are often carried out during cooler times of the year, such as in the winter (June-August) for the Martu, which results in slow, cool and low-intensity fires that reduce the potential for wildfires.
Although the study remains cautious about extrapolating the specific findings about plant-fire relationships beyond the biome of the study area, the authors say broader messages about the importance of Indigenous fire regimes ring true elsewhere.
“Our work builds on an emerging narrative of the importance of Indigenous fire regimes in the maintenance of fire-prone ecosystems across the world, with lots of important work happening in Australia and overseas,” Greenwood said.
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Banner image: Flowers of Scaevola parvifolia, found in the arid regions of Western Australia, central Australia and Queensland. Image by Kevin Thiele via Flickr (CC BY 2.0).
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Citations:
Greenwood, L., Bliege Bird, R., McGuire, C., Jadai, N., Price, J., Skroblin, A., … Nimmo, D. (2024). Indigenous pyrodiversity promotes plant diversity. Biological Conservation, 291, 110479. doi:10.1016/j.biocon.2024.110479
Davis, H., Ritchie, E. G., Avitabile, S., Doherty, T., & Nimmo, D. G. (2018). Testing the assumptions of the pyrodiversity begets biodiversity hypothesis for termites in semi-arid Australia. Royal Society Open Science, 5(4), 172055. doi:10.1098/rsos.172055
Lindenmayer, D., Taylor, C., Blanchard, W., Zylstra, P., & Evans, M. J. (2023). What environmental and climatic factors influence multidecadal fire frequency? Ecosphere, 14(8). doi:10.1002/ecs2.4610
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