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Bad fire science can kill our threatened species. It's time to cooperate with nature

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Wednesday, December 14, 2022

ShutterstockFor four years, naturalist Allison Dixon regularly walked from dusk until dawn at the Warrungup Spring bush reserve south of Perth, carefully documenting every western ringtail possum she saw. The possum – or ngwayir in the language of Traditional Owners – is critically endangered. The species is found only in a small area of southwest Australia, including the population of 22 individuals Dixon was monitoring. She knew each possum by name. Their voices and physical features were as familiar to her as human faces. In 2018, a prescribed burn by local authorities was conducted in the Warrungup Spring reserve. Despite burning slowly as planned, it killed 17 of the 22 possums Dixon was monitoring. I document this incident in a new paper and explore how a carefully controlled fuel reduction burn could cause such catastrophic loss. We must move on from bad fire science to prevent similar tragedies. Allison Dixon carefully monitored a population of western ringtail possums. Facebook The fire-intensity equation Prescribed burning occurs when authorities intentionally set fire to a particular area of the landscape under defined conditions. The burns are often used to reduce so-called “fuel loads” – fine biomass such as twigs, leaf litter and bark. As the idea goes, the greater the weight of the fuel load, the more flammable the forest. This theory can be traced back to American fire researcher George Marsden Byram. In 1959, Byram published an equation beautiful in its simplicity: a fire’s heat output (or intensity) was equal to the amount of energy stored in the fuel, multiplied by the amount of fuel, and multiplied again by the speed the fire spreads and consumes it. This theory would shape a central tenet of Australian fire management: that prescribed burns are necessary to reduce fuel loads, to make subsequent bushfires less intense. Prescribed burns are central to Australian fire management. Greg Barnette/The Record Searchlight The influence of Byram’s fire-intensity theory can be seen in an official fire management guide used to inform the burning of ngwayir habitat. The document suggests the animals can survive low-intensity fire – and on the day of the burn that killed 17 ngwayir, weather conditions were conducive to such a fire. But after years of work in fire management, I’ve come to see Byram’s theory – and the management practices flowing from it – as simplistic. In 2016, my colleagues and I published a new way of modelling fire behaviour. In my latest paper, I applied this model to the Warrungup Spring fire. Read more: New modelling on bushfires shows how they really burn through an area The prescribed burn at Warrungup Spring involved igniting patches of balga grasstrees and their surrounds. I investigated what happened to the air around a hollow in a tree where ngwayir were known to live. A balga grasstree burned during the fire was located under the hollow. According to Byram’s theory, the fire would have been classed as low-intensity because it did not spread horizontally. But this thinking does not account for the vertical spread of heat and flames. As depicted in the image below, the supposedly low-intensity fire would have heated the air above it to more than 500℃. This would burn the respiratory tracts of possums inside the hollow in just a few minutes. Byram’s fire-intensity equation might be valuable as a theoretical construct. But using it to inform real-world fire management can be catastrophic. A ngwayir and its hollow located above a balga grasstree set on fire in the prescribed burn. The graph shows the heat penetration into the hollow in increments through the wood, with the hollow temperature in red and the lethal temperature marked by the horizontal line. A. Dixon; P. Zylstra As my latest paper describes, Allison Dixon searched for the western ringtail possums the evening after the fire, and each subsequent evening for two weeks. In some cases, Dixon found the bodies. In others, the presence of flies in high nest hollows indicated the ngwayir inside had perished. Dixon visited surrounding properties and structures in case the possums had fled the fire ground, but no survivors were identified. She also continued weekly monitoring of their habitat. In the end, 17 of the 22 critically endangered possums were presumed dead. A burnt western ringtail possum recorded by Allison Dixon after the prescribed burn in 2018. Source: Allison Dixon But the problem runs even deeper Most fuel load lies in the litter layer on the ground. But we’ve known for decades that burning it away germinates dense understorey regrowth. In fact, WA government records show bushfires are most likely where prescribed burns have occurred, where that regrowth is most dense. In November this year, a prescribed burn was conducted in the Walpole Wilderness, in dense regrowth stimulated by a previous prescribed burn. The fire was reportedly meant to protect quokka habitat. But it escaped containment lines and burnt 25,000 hectares – 10,000 more than originally planned, and at a higher-than-intended severity. A prescribed burn that escaped in the Walpole Wilderness this year. Author provided One peer-reviewed study appears to show less fire in areas where prescribed burning has been undertaken. But research by my colleagues and I has challenged this study. The authors of the study in question compared the amount of wildfire in each six-year period with the amount of prescribed fire in the same period. But this method meant that for some of that period, reduced fire frequency was attributed to prescribed burns that had not yet occurred. Cooperating with nature Australia has the world’s worst record for mammal extinction – and we know fire is one of the main culprits. Yet prescribed burning relies on outdated or even disproved theories and assumptions about fire. Bad fire science is killing our threatened species, but alternatives are available. These approaches reinforce, rather than disrupt, natural ecological controls on forest fire. They include traditional Indigenous fire knowledge, and modern techniques to minimise the extent of dense regrowth in the landscape. By cooperating with nature to minimise fire risk, we can protect species that have persisted through aeons. Read more: Coming of age: research shows old forests are 3 times less flammable than those just burned Philip Zylstra received funding for this study from the NSW Environmental Trust, Curtin University and the San Diego Zoo Wildlife Alliance.

A new paper explores how a carefully controlled fuel reduction burn killed 17 critically endangered western ringtail possums.

Shutterstock

For four years, naturalist Allison Dixon regularly walked from dusk until dawn at the Warrungup Spring bush reserve south of Perth, carefully documenting every western ringtail possum she saw.

The possum – or ngwayir in the language of Traditional Owners – is critically endangered. The species is found only in a small area of southwest Australia, including the population of 22 individuals Dixon was monitoring.

She knew each possum by name. Their voices and physical features were as familiar to her as human faces.

In 2018, a prescribed burn by local authorities was conducted in the Warrungup Spring reserve. Despite burning slowly as planned, it killed 17 of the 22 possums Dixon was monitoring.

I document this incident in a new paper and explore how a carefully controlled fuel reduction burn could cause such catastrophic loss. We must move on from bad fire science to prevent similar tragedies.

woman in hat leans against tree
Allison Dixon carefully monitored a population of western ringtail possums. Facebook

The fire-intensity equation

Prescribed burning occurs when authorities intentionally set fire to a particular area of the landscape under defined conditions. The burns are often used to reduce so-called “fuel loads” – fine biomass such as twigs, leaf litter and bark.

As the idea goes, the greater the weight of the fuel load, the more flammable the forest. This theory can be traced back to American fire researcher George Marsden Byram.

In 1959, Byram published an equation beautiful in its simplicity: a fire’s heat output (or intensity) was equal to the amount of energy stored in the fuel, multiplied by the amount of fuel, and multiplied again by the speed the fire spreads and consumes it.

This theory would shape a central tenet of Australian fire management: that prescribed burns are necessary to reduce fuel loads, to make subsequent bushfires less intense.

here
Prescribed burns are central to Australian fire management. Greg Barnette/The Record Searchlight

The influence of Byram’s fire-intensity theory can be seen in an official fire management guide used to inform the burning of ngwayir habitat. The document suggests the animals can survive low-intensity fire – and on the day of the burn that killed 17 ngwayir, weather conditions were conducive to such a fire.

But after years of work in fire management, I’ve come to see Byram’s theory – and the management practices flowing from it – as simplistic. In 2016, my colleagues and I published a new way of modelling fire behaviour. In my latest paper, I applied this model to the Warrungup Spring fire.


Read more: New modelling on bushfires shows how they really burn through an area


The prescribed burn at Warrungup Spring involved igniting patches of balga grasstrees and their surrounds. I investigated what happened to the air around a hollow in a tree where ngwayir were known to live. A balga grasstree burned during the fire was located under the hollow.

According to Byram’s theory, the fire would have been classed as low-intensity because it did not spread horizontally. But this thinking does not account for the vertical spread of heat and flames.

As depicted in the image below, the supposedly low-intensity fire would have heated the air above it to more than 500℃. This would burn the respiratory tracts of possums inside the hollow in just a few minutes.

Byram’s fire-intensity equation might be valuable as a theoretical construct. But using it to inform real-world fire management can be catastrophic.

A ngwayir and its hollow located above a balga grasstree set on fire in the prescribed burn. The graph shows the heat penetration into the hollow in increments through the wood, with the hollow temperature in red and the lethal temperature marked by the horizontal line. A. Dixon; P. Zylstra

As my latest paper describes, Allison Dixon searched for the western ringtail possums the evening after the fire, and each subsequent evening for two weeks.

In some cases, Dixon found the bodies. In others, the presence of flies in high nest hollows indicated the ngwayir inside had perished.

Dixon visited surrounding properties and structures in case the possums had fled the fire ground, but no survivors were identified. She also continued weekly monitoring of their habitat. In the end, 17 of the 22 critically endangered possums were presumed dead.

burnt possum lies in ash
A burnt western ringtail possum recorded by Allison Dixon after the prescribed burn in 2018. Source: Allison Dixon

But the problem runs even deeper

Most fuel load lies in the litter layer on the ground. But we’ve known for decades that burning it away germinates dense understorey regrowth. In fact, WA government records show bushfires are most likely where prescribed burns have occurred, where that regrowth is most dense.

In November this year, a prescribed burn was conducted in the Walpole Wilderness, in dense regrowth stimulated by a previous prescribed burn.

The fire was reportedly meant to protect quokka habitat. But it escaped containment lines and burnt 25,000 hectares – 10,000 more than originally planned, and at a higher-than-intended severity.

smoke fills the sky above hills
A prescribed burn that escaped in the Walpole Wilderness this year. Author provided

One peer-reviewed study appears to show less fire in areas where prescribed burning has been undertaken. But research by my colleagues and I has challenged this study.

The authors of the study in question compared the amount of wildfire in each six-year period with the amount of prescribed fire in the same period. But this method meant that for some of that period, reduced fire frequency was attributed to prescribed burns that had not yet occurred.

Cooperating with nature

Australia has the world’s worst record for mammal extinction – and we know fire is one of the main culprits. Yet prescribed burning relies on outdated or even disproved theories and assumptions about fire.

Bad fire science is killing our threatened species, but alternatives are available. These approaches reinforce, rather than disrupt, natural ecological controls on forest fire. They include traditional Indigenous fire knowledge, and modern techniques to minimise the extent of dense regrowth in the landscape.

By cooperating with nature to minimise fire risk, we can protect species that have persisted through aeons.


Read more: Coming of age: research shows old forests are 3 times less flammable than those just burned


The Conversation

Philip Zylstra received funding for this study from the NSW Environmental Trust, Curtin University and the San Diego Zoo Wildlife Alliance.

Read the full story here.
Photos courtesy of

Toyota SUV adverts banned in UK on environmental grounds

Advertising Standards Authority says Hilux poster and video condone driving that disregards ‘impact on nature’The UK advertising watchdog has banned two Toyota adverts for condoning driving that disregards its environmental impact in a landmark ruling, stating that the SUV ads had been created without “a sense of responsibility to society”.It is the first time the Advertising Standards Authority (ASA) has blocked an SUV advert on the grounds of breaching social responsibility in an environmental context. Continue reading...

The UK advertising watchdog has banned two Toyota adverts for condoning driving that disregards its environmental impact in a landmark ruling, stating that the SUV ads had been created without “a sense of responsibility to society”.It is the first time the Advertising Standards Authority (ASA) has blocked an SUV advert on the grounds of breaching social responsibility in an environmental context.The regulator barred two ads, first released in a 2020 campaign: a poster and a video shown on social media, where dozens of Toyota Hilux cars drive across off-road terrain, including a river, while a voiceover describes the scene as “one of nature’s true spectacles”. The vehicles then join a road and drive through an urban area, before a lone car enters a driveway, with the voiceover continuing: “Toyota Hilux. Born to roam.” The poster shows two SUVs in the foreground, followed by a swarm of others traversing a rocky terrain over a cloud of dust.The complaint was lodged by Adfree Cities, a network of groups trying to get advertising out of public spaces. They argued, in partnership with the UK campaign group Badvertising, that the adverts condoned environmentally harmful behaviour, and are calling for an end to advertising of high-carbon products and services.The ASA ruled that the adverts “condoned the use of vehicles in a manner that disregarded their impact on nature and the environment … they had not been prepared with a sense of responsibility to society”.A poster showing two Toyota Hilux SUVs followed by a swarm of others. Photograph: Advertising Standards Authority/PAVeronica Wignall, a co-director at Adfree Cities, said: “These adverts epitomise Toyota’s total disregard for nature and the climate, by featuring enormous, highly polluting vehicles driving at speed through rivers and wild grasslands.”Wignall said there was a disconnect between the way SUVs were advertised – with campaigns often depicting them in rugged environments – and the reality of where they were largely driven. Research has shown that three-quarters of new SUVs in the UK are registered to people in urban areas. “It’s a cynical use of nature to promote something incredibly nature-damaging.”She said: “This ruling is a good moment to think about the limitations of what the regulator can do,” noting that the body relied on civil society to monitor ads for potential harm. “The ASA can only act on adverts that are environmentally damaging through breaches of advertising codes … But the harms caused by high-carbon advertising go much deeper than that.“Advertising for SUVs is pushing up demand for massive gas-guzzling, highly polluting cars in urban environments, just when we want streets that are safer and cleaner and an [accessible] low carbon transport system,” Wignall said, adding that the situation was similar for flights, meat and dairy.She called for the government to “stop high-carbon advertising at source” with a tobacco-style ban. “Similarly, climate breakdown is increasingly damaging health in the UK, as well as obviously across the world where impacts are felt more severely.”Toyota defended the Hilux campaign by arguing that the vehicle was designed for the toughest environments, with those working in industries including farming and forestry having a genuine need for off-road vehicles. It did not depict any such workers in the commercial, but it said it should not have to.In 2021 the regulator announced plans for a series of investigations into environmental advertising claims and practices. In a submission to the House of Lords that year, the ASA noted that it received few complaints related to social responsibility, describing it as “an area that we believe will require greater regulatory scrutiny in future”.skip past newsletter promotionSign up to Business TodayGet set for the working day – we'll point you to all the business news and analysis you need every morningPrivacy Notice: Newsletters may contain info about charities, online ads, and content funded by outside parties. For more information see our Privacy Policy. We use Google reCaptcha to protect our website and the Google Privacy Policy and Terms of Service apply.after newsletter promotionThe ASA has previously issued a draft ruling banning adverts for a Land Rover Defender off-roader in 2021 on social responsibility grounds, before overturning it.A Toyota spokesperson said: “Toyota does not condone behaviour that is harmful to the environment. In fact, over the course of the past three decades, not only has Toyota been one of the leaders in the automotive field in terms of carbon emissions reduction across its vehicle offering, it has shared hundreds of royalty-free licences, allowing others to use its electrification technology.“As part of its wide range of global vehicle offerings, Toyota caters for customers who require a mobility option for reliable use in the harshest of terrains – those people who operate in off-road and remote settings.”The spokesperson said footage in the advert had been shot on private land abroad, a non-UK location, with permission and “in a non-ecologically sensitive environment”, adding that the poster ad used computer-generated imagery and so had “no environmental impact”.While the definition of an SUV varies, the vehicles have surged in popularity in recent years in the UK to account for almost a third of vehicles sold. In Europe, the share of SUVs in new car registrations hit a record 51% this year.The effect of rising sales of SUVs, and the fact they tend to be heavier than the traditional models previously bought, means the average conventional-engined car bought in 2023 has higher carbon emissions than its 2013 equivalent, according to the climate campaign organisation Possible.

At the Portrait Gallery: ‘Forces of Nature,’ for good and ill

National Portrait Gallery show features subjects who have helped advance — and, in some instances, resisted — environmental stewardship.

The term for a likeness that captures a person in her or his defining home or workplace is “environmental portrait.” There are many of those in the National Portrait Gallery’s “Forces of Nature: Voices That Shaped Environmentalism.” But nearly as common are pictures such as the show’s oldest entry, an unknown artist’s small rendering of Henry David Thoreau, circa 1863, in which the “Walden” author looks as if he’s dressed for afternoon tea.Of course, he might have been. Thoreau’s celebrated haven in the woods was a short walk from the home of the property’s owner, Ralph Waldo Emerson, the author’s close friend. “Walden” remains influential for people who seek a return to nature, but Thoreau didn’t venture nearly so far into the wilderness as other 19th- and early-20th-century Americans pictured in this survey focusing on scientists, politicians, writers, artists and others who have helped advance — and, in some instances, resisted — environmental stewardship.Carl Everton Moon’s 1909 photograph of author and naturalist John Burroughs and Sierra Club co-founder John Muir shows them together at the Grand Canyon. Underwood & Underwood’s 1903 stereoscopic photo of presidential outdoorsman Teddy Roosevelt and a group of companions (including Muir) was made at the base of a giant sequoia. Gifford Pinchot, the first head of the U.S. Forest Service, also traveled far into the West, but Pirie MacDonald’s 1909 photo of him is no wilder than that of Thoreau.The museum owns more than 2,000 artworks originally made for the cover of Time magazine, so it’s hardly a surprise that some of them are included in this show. Mathias Klarwein’s 1970 illustration splits the face of ecologist and professor Barry Commoner between full color and reversed black and white, keyed to landscape backdrops that are, respectively, utopian and catastrophic. Also made for Time are Raul Vega’s 1980 photograph of cosmologist Carl Sagan standing in the surf fully clothed, and another split image that’s not technically a portrait: “Toxic Wastes,” James Marsh’s 1985 acrylic-on-board painting in which an anonymous man’s head turns skeletal below the surface of an apparently corrosive body of water.Two other pieces of Time cover art may come as thematic surprises. Mark Hess’s 1982 painting depicts James Watt, Ronald Reagan’s first secretary of the interior, depicted in front of a stylized rendering of the United States — whose public lands he appears ready to sell off. Dixy Lee Ray, the pro-development and pro-nuclear-power governor of Washington state from 1977 to 1981, is portrayed with her head grafted onto the body of an American goldfinch (the state bird) in David Palladini’s 1977 drawing in crayon, gouache and ink. Both former officials might be classified as forces against, rather than for, nature.The inclusion of Watt and Ray isn’t really explained, but the show is not divided equally between those who would preserve the planet and those who, for whatever reason, are not concerned about that. The only other subject who might be classified as an anti-environmentalist is Freeman Dyson, a physicist who in his final years became a critic of climate-change scientists, in a Francis Bello photograph.The show does feature portraits of people who are not known — or at least not known primarily — for their environmental campaigns. Among these are Prentice H. Polk’s photo of agricultural scientist George Washington Carver; Rudy Rodriguez’s photo of Dolores Huerta, the organizer of migrant farmworkers; and an unidentified picture of American Indian Movement activists Dennis Banks and Russell Means, depicted together by an unknown photographer during the 1973 armed occupation of Wounded Knee, S.D. But each of those subjects was concerned with the state of nature, even if indirectly.Coincidentally, all of the three-dimensional likenesses are of women. Two are bronze busts of authors: Rachel Carson (“Silent Spring”) by Una Hanbury, and Mary Austin (“The Land of Little Rain”) by Ida Rauh. The third is a small 3D print: a full-body color scan of Vietnam Veterans Memorial designer Maya Lin, who is now overseeing a different sort of memorial: a multimedia project about environmental and climate crises, “What Is Missing?”Among the most contemporary pieces are large paintings that exemplify a trend toward less formal and more playful portraits reflected in the museum’s recent acquisitions. Evolutionary biologist Edward O. Wilson communes with ants, a longtime interest, in Jennie Summerall’s 2006 painting, and tropical hues and cartoonishly outlined forms characterize Hope Gangloff’s 2019 painting of Julie Packard, the executive director of the Monterey Bay Aquarium. The contrast between these approachable images and the more solemn one of Thoreau demonstrates a notable development over the last 160 years. But that change is in art, which will probably prove less significant than the changes Mother Earth is undergoing.Forces of Nature: Voices That Shaped EnvironmentalismNational Portrait Gallery, Eighth and F streets NW. npg.si.edu.

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