Many of our plants and animals have adapted to fires, but now the fires are changing



Eucalypt seeds don’t fall far from the tree, meaning repopulating large areas of forest will be difficult.
from http://www.shutterstock.com

Cris Brack, Australian National University

Australia is a land that has known fire. Our diverse plant and animal species have become accustomed to life with fire, and in fact some require it to procreate.

But in recent decades the pattern of fires – also known as the fire regime – is changing. Individual fires are increasingly hotter, more frequent, happening earlier in the season and covering larger areas with a uniform intensity. And these changes to the fire regime are occurring too fast for our native flora and fauna to adapt and survive.




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Our fire-adapted plants are suffering

Many of Australia’s iconic eucalypts are “shade intolerant” species that adapted to exist within a relatively harsh fire regime. These species thrive just after a major fire has cleared away the overstory and prepared an ash bed for their seeds to germinate.

Some of our most majestic trees, like the alpine ash, can only regenerate from seed. Those seeds germinate only on bare earth, where the leaf litter and shrubs have been burnt away.

But if fire is so frequent the trees haven’t matured enough to produce seed, or so intense it destroys the seeds present in the canopy and the ground, then even these fire-adapted species can fail.

The current fires are re-burning some forests that were burnt only a decade ago. Those regenerating trees are too young to survive, but also too young to have started developing seed.

With the disappearance of these tree species, other plants will fill the gap. Acacias (wattles) are potential successors as they mature much earlier than alpine ash. Our tall, majestic forests could easily turn into shrubby bushland with more frequent fires.

Wattles mature early and could take over Eucalypts.
from http://www.shutterstock.com

Even within a burnt area, there are usually some unburnt patches, which are highly valuable for many types of plants and animals. These patches include gullies and depressions, but sometimes are just lucky coincidences of the terrain and weather. The patches act as reserves of “seed trees” to provide regeneration opportunities.

Recent fires, burning in hotter and drier conditions, are tending to be severe over large areas with fewer unburnt patches. Without these patches, there are no trees in the fire zone to spread seeds for regeneration.

Eucalypt seed is small and without wings or other mechanisms to help the wind disperse it. Birds don’t generally disperse these seeds either. Eucalypt seed thus only falls within 100 – 200 metres of the parent tree. It may take many decades for trees to recolonise a large burnt area.

That means wind-blown or bird-dispersed seeds from other species may fully colonise the burnt area well before the Eucalypts. Unfortunately many of these windblown seeds will be weed species, such as African Love Grass, which may then cover the bare earth and exclude successful Eucalypt regeneration while potentially making fires even hotter and more frequent.

Animals have fewer places to hide

Young animals are significantly more vulnerable to disturbances such as fire than mature individuals. So the best time to give birth is a season when fire is rare.

Spring in the southern zones of Australia has, in the past, been wetter and largely free from highly destructive fires. Both flora and fauna species thus time their reproduction for this period. But as fire seasons lengthen and begin earlier in the year, vulnerable nestlings and babies die where they shelter or starve as the fires burn the fruits and seeds they eat.

Australian fauna have developed behaviours that help them survive fire, including moving towards gullies and depressions, climbing higher, or occupying hollows and burrows (even if not their own) when they sense fire.

Many native animals have learnt to sense fire and take cover, but with greater areas burning, there are fewer places to hide.
from http://www.shutterstock.com

But even these behaviours will fail if those refuges are uncharacteristically burning under hotter and drier conditions. Rainforest, marshes and the banks of watercourses were once safe refuges against fire, but we have seen these all burn in recent fires.




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What can be done?

All aspects of fire regimes in Australia are clearly changing as a result of our heating and drying climate. But humans can have a deliberate effect, and have done so in the past.

Indigenous burning created a patchwork of burnt areas and impacted on the magnitude and frequency of fires over the landscape. These regular burns kept the understory under control, while the moderate intensity and patchiness allowed larger trees to survive.




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There have been repeated calls of late to reintroduce Indigenous burning practices in Australia. But this would be difficult over vast areas. It requires knowledgeable individuals to regularly walk through each forest to understand the forest dynamics at a very fine scale.

More importantly, our landscapes are now filled with dry fuel, and shrubs that act as “ladders” – quickly sending any fire into tree canopies to cause very destructive crown fires. Given these high fuel conditions along with their potentially dangerous distribution, there may be relatively few safe areas to reintroduce Indigenous burning.

The changed fire conditions still require active management of forests, with trained professionals on the ground. Refuges could be developed throughout forests to provide places where animals can shelter and from which trees can recolonise. Such refuges could be reintroduced by reducing forest biomass (or fuel) using small fires where feasible or by mechanical means.

A Kangaroo Island landscape devastated by fire.
David Mariuz/AAP

Biomass collected by machines could be used to produce biochar or other useful products. Biochar could even be used to improve the soil damaged by the fires and excess ash.

Midstory species could be cut down to prevent the development of fire ladders to tree crowns. Even the overstory could be thinned to minimise the potential for crown fires. Seed could also be collected from thinned trees to provide an off-site bank as ecological insurance.

Such active management will not be cheap. But using machinery rather than fire could control biomass quantity and distribution in a much more precise way: leaving some biomass on the ground as habitat for insects and reptiles, and removing other patches to create safer refuges from the fires that will continue to come.The Conversation

Cris Brack, Associate Professor, Fenner School of Environment and Society, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Six million hectares of threatened species habitat up in smoke



At least 250 threatened species have had their habitat hit by fires.
Gena Dray

Michelle Ward, The University of Queensland; Aaron Greenville, University of Sydney; April Reside, The University of Queensland; Ayesha Tulloch, University of Sydney; Brooke Williams, The University of Queensland; Emily Massingham, The University of Queensland; Helen Mayfield, The University of Queensland; Hugh Possingham, The University of Queensland; James Watson, The University of Queensland; Jim Radford, La Trobe University, and Laura Sonter, The University of Queensland

More than one billion mammals, birds, and reptiles across eastern Australia are estimated to have been affected by the current fire catastrophe.

Many animals and plants have been incinerated or suffocated by smoke and ash. Others may have escaped the blaze only to die of exhaustion or starvation, or be picked off by predators.



But even these huge losses of individual animals and plants do not reveal the full scale of impact that the recent fires have had on biodiversity.

Plants, invertebrates, freshwater fish, and frogs have also been affected, and the impact of the fires is likely to be disproportionately greater for threatened species.




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To delve deeper into the conservation impact, we used publicly available satellite imagery to look at the burnt areas (up to January 7, 2020) and see how they overlapped with the approximate distributions of all the threatened animals and plants listed under the Environment Protection and Biodiversity Conservation Act.

We restricted our analysis to the mediterranean and temperate zone of south-east and south-west Australia.

The bad news

We found that 99% of the area burned in the current fires contains potential habitat for at least one nationally listed threatened species. We conservatively estimate that six million hectares of threatened species habitat has been burned.



Given that many fires are still burning and it is not yet clear how severe the burning has been in many areas, the number of species affected and the extent of the impact may yet change.

What we do know is that these species are already on the brink of extinction due to other threats, such as land clearing, invasive species, climate change, disease, or previous fires.

Approximately 70 nationally threatened species have had at least 50% of their range burnt, while nearly 160 threatened species have had more than 20% of their range burnt.

More threatened plants have been affected than other groups: 209 threatened plant species have had more than 5% of their range burnt compared to 16 mammals, ten frogs, six birds, four reptiles, and four freshwater fish.


Author supplied

Twenty-nine of the 30 species that have had more than 80% of their range burnt are plants. Several species have had their entire range consumed by the fires, such as the Mountain Trachymene, a fire-sensitive plant found in only four locations in the South Eastern Highlands of NSW.

Other species that have been severely impacted include the Kangaroo Island dunnart and the Kangaroo Island glossy black cockatoo. These species’ entire populations numbered only in the hundreds prior to these bushfires that have burned more than 50% of their habitat.

The Kangaroo Island glossy black cockatoo has had more than 50% its habitat impacted by fire.
Mike Barth

Glossy black cockatoos have a highly specialised diet. They eat the seeds of the drooping sheoak (Allocasuarina verticillata). These trees may take anywhere from 10 to 50 years to recover enough to produce sufficient food for the black cockatoos.

The populations of many species will need careful management and protection to give their habitats enough time to recover and re-supply critical resources.

The figures above do not account for cumulative impacts of previous fires. For example, the critically endangered western ground parrot had around 6,000 hectares of potential habitat burnt in these fires, which exacerbates the impact of earlier extensive fires in 2015 and early 2019.

Threatened species vary in their ability to cope with fire. For fire-sensitive species, almost every individual dies or is displaced. The long-term consequences are likely to be dire, particularly if vegetation composition is irrevocably changed by severe fire or the area is subject to repeat fires.

More than 50% of the habitat of several species known to be susceptible to fire has been burnt – these include the long-footed potoroo and Littlejohn’s tree frog.

The endangered long-footed potoroo has had more than 50% of its potential habitat impacted by fire.
George Bayliss

Some species are likely to thrive after fire. Indeed, of the top 30 most impacted species on our list, almost 20% will likely flourish due to low competition in their burnt environments – these are all re-sprouting plants. Others will do well if they are not burnt again before they can set seed.

Rising from the ashes

For fire-sensitive threatened species, these fires could have substantially increased the probability of extinction by virtue of direct mortality in the fires or reducing the amount of suitable habitat. However, after the embers settle, with enough investment and conservation actions, guided by evidence-based science, it may be possible to help threatened species recover.

For species on the brink of extinction, insurance populations need to be established. Captive breeding and release can complement wild populations, as occurs for the regent honeyeater.
Dean Ingwersen / BirdLife Australia

Protection and conservation-focussed management of areas that have not burned will be the single most important action if threatened species are to have any chance of persistence and eventual recovery.

Management of threatening processes (such as weeds, feral predators, introduced herbivores, and habitat loss through logging or thinning) must occur not just at key sites, but across the landscapes they sit in. Maintaining only small pockets of habitat in a landscape of destruction will lock many species on the pathway to extinction.

In some cases, rigorous post-fire restoration will be necessary to allow species to re-colonise burnt areas. This may include intensive weed control and assisted regeneration of threatened flora and specific food sources for fauna, installing nest boxes and artificial cover, or even targeted supplementary feeding.

Unconventional recovery actions will be needed because this unique situation calls for outside-the-box thinking.




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Playing the long game

These fires were made larger and more severe by record hot, dry conditions. Global temperatures have so far risen by approximately 1°C from pre-industrial levels.

Current projections indicate that we are on track for a 3°C increase. What will that look like?

We are in a moment of collective grief for what has been lost. A species lost is not just a word on a page, but an entire world of unique traits, behaviours, connections to other living things, and beauty.

These losses do not need to be in vain. We have an opportunity to transform our collective grief into collective action.

Australians are now personally experiencing climate impacts in an unprecedented way. We must use this moment to galvanise our leaders to act on climate change, here in Australia and on the world stage.

The futures of our beloved plants and animals, and our own, depend on it.The Conversation

Michelle Ward, PhD Candidate, The University of Queensland; Aaron Greenville, Lecturer in Spatial Agricultural and Environmental Sciences, University of Sydney; April Reside, Researcher, Centre for Biodiversity and Conservation Science, The University of Queensland; Ayesha Tulloch, DECRA Research Fellow, University of Sydney; Brooke Williams, PhD Candidate, The University of Queensland; Emily Massingham, PhD Student, The University of Queensland; Helen Mayfield, Postdoctoral Research Fellow School of Earth and Environmental Sciences, The University of Queensland; Hugh Possingham, Professor, The University of Queensland; James Watson, Professor, The University of Queensland; Jim Radford, Principal Research Fellow, Research Centre for Future Landscapes, La Trobe University, and Laura Sonter, PhD Candidate in Global Environmental Change, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bushfires left millions of animals dead. We should use them, not just bury them


Emma Spencer, University of Sydney; Chris Dickman, University of Sydney; Philip Barton, Australian National University, and Thomas Newsome, University of Sydney

Bushfires this season have left an estimated 1 billion dead animals in their wake, their carcasses dotting the blackened landscape.

Adding to the toll, farmers are being forced to euthanise injured and starving livestock and there are also calls to cull feral animals in fire-affected areas, including by aerial shooting.

The carcasses have already been flagged as a potential biosecurity threat, and the Australian Defence Force is tasked with collecting and burying the dead in mass graves.




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There’s logic in this. Carcasses can harbour nasty diseases such as botulism that threaten human, livestock and wildlife health. They also provide food for invasive pests like feral cats and red foxes.

But carcasses can play a positive role as landscapes recover from fire, providing rich nutrients for other native animal, microbial and plant species.

Carcasses provide important food sources to native animals, such as the lace goanna.

The Morrison Government has announced a A$50 million package to help wildlife and habitat recover from the fires, and yesterday met leading wildlife experts and environment groups to get advice on the recovery process.

We suggest this process should examine carcass disposal methods other than burial, such as composting – effectively “recycling” the dead. It should also involve monitoring the carcasses that remain to understand both their positive and negative roles in fire-ravaged areas.

The positives: carcasses feed the living

Carcasses feed a range of native animals, including goannas, wedge-tailed eagles and dingoes. Post-fire, they can provide an alternative source of food for struggling native predators and pollinators. And feeding hungry predators with carcasses could redirect them away from vulnerable prey.

Carcasses also feed insects such as flies, ants, beetles, and their larvae, and support important ecological processes such as pollination.

As they decompose, nutrients leach from carcasses into the surrounding environment and create “halos” of greenery in the landscape, where vegetation thrives around carcass sites. Their influence on soil and plant communities can last for years.

Vegetation growth ‘halo’ around a kangaroo carcass. When animals die their nutrients can influence the landscape for years.

The negatives: spreading disease and sustaining feral animals

Carcasses are home to bacteria that help break down animal tissues. But some carcasses also harbour harmful pathogens that bring disease.

For a disease outbreak to happen, the animal must generally have already been carrying dangerous infectious agents, like Anthrax or the Hendra virus, before they died. And many of these pathogens will not survive long on dead hosts.




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Leaving carcasses out in the open can also feed introduced predators such as feral cats and red foxes, putting small native animals at risk. Some weeds thrive in the nutrient-rich soils around carcasses too.

Introduced insects like the European wasp, which appeared en masse following fires in Kosciuszko National Park, also take advantage of carcass resources. These wasps are highly aggressive and attack and kill other native insects.

How long does a carcass stick around?

We know very little about the ecological role of carcasses in fire-affected areas, and it’s important that more research is carried out.

We know burnt animals can decompose faster than other carcasses and harbour different types of insect scavengers.

However the recent fires are likely to have wiped out entire scavenger communities, including larger scavengers like dingoes and eagles, that help to clean our landscapes of dead animals.

The effects of this are unknown, but could mean that carcasses stick around in the environment for prolonged periods, even months.

A feral cat scavenging on an animal carcass. Animal carcasses could increase the number of feral predators.

Finding the right solution to a grisly problem

As climate change accelerates the number of natural disasters and mass animal deaths, more thought and planning must be put into carcass management.

In Australia, carcasses are often dealt with by not dealing with them: they’re left to rot. This happened for almost 100 feral horses that died last year at an empty water hole during a heatwave.

Animals culled in national parks and on farmlands are also often left to decay, untouched, as are the many dead animals that commonly line our country roads. But in landscapes where feral species are common, or where livestock or people are likely to encounter carcasses, leaving them alone isn’t the best option.




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Carcasses are more often buried following disease outbreaks or when livestock die. We saw this during the 2019 Queensland floods, where thousands of drowned cattle were buried in mass graves.

Burial is a relatively inexpensive, fast and effective method of dealing with the dead. But it must be done carefully to avoid polluting groundwater sources and causing nutrients like nitrogen to build up.

Burying carcasses can also be compared to sending rubbish to the tip. Breakdown will be slow, and no useful end product is created.

A more useful option

An alternative option is to “recycle” carcasses by composting them. Composting can accelerate the decomposition of animal tissues and is environmentally friendly, capturing nutrients.




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Composting kills most pathogens, whereas burial just moves the problem underground. It also suppresses smelly odours and doesn’t attract scavengers. The usable organic material resulting from the composting can also be applied to nutrient-poor soil.

Getting used to the ‘yuck’ factor of carcasses.

Composting can be time-consuming and hard to get right. It requires careful monitoring of temperature and moisture content to ensure all disease-causing pathogens are killed, and odours are suppressed.

There’s also a “yuck” factor and the public would probably need convincing for the method to be widely adopted.

But whatever option we choose, it’s clear there’s more we can do with carcasses than simply burying them.The Conversation

Emma Spencer, Ph.D. student, University of Sydney; Chris Dickman, Professor in Terrestrial Ecology, University of Sydney; Philip Barton, Honorary Senior Lecturer, Fenner School of Environment and Society, Australian National University, and Thomas Newsome, Lecturer, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Tales of wombat ‘heroes’ have gone viral. Unfortunately, they’re not true



Wombats may not usher other animals into their burrows, but their warrens still protect other species in bushfires.
Liv Falvey/Shutterstock

Dale Nimmo, Charles Sturt University

If you’ve been following the bushfire crisis on social media and elsewhere, you may have seen reports of benevolent wombats herding other animals to shelter into their fire-proof burrows.

These stories went quickly viral – probably reflecting the appetite for good news after the horrors of the bushfire crisis. However the accounts are not entirely accurate.

Wombats do not heroically round up helpless animals during a bushfire and lead them to safety. But wombats do help other animals in a different way – even if it’s not their intention.

Accidental heroes

Wombats can emerge as accidental heroes during a bushfire, by providing a safe refuge underground for other wildlife.

Wombat warrens – networks of interconnecting burrows – are large and complex, and considerably shielded from the above-ground environment. Small mammals are known to use wombat burrows to survive an inferno.

One study of the southern hairy-nosed wombat, for instance, found warrens with 28 entrances and nearly 90 metres of tunnels.

Wombats aren’t benevolent. They’re accidental heroes.

What’s more, temperatures deep within burrows are very stable compared to surface temperatures, with daily temperature fluctuations of less than 1℃, compared to 24℃ on the surface.

This thermal buffering would help a great deal during intense fires, and you can understand why other species would want access to these safe havens.

The wombat sharehouse

By placing camera traps outside 34 wombat burrows, a 2015 study showed a surprising variety of animals using southern hairy-nosed wombat burrows. Researchers observed ten other species, six of which used them on multiple occasions.




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The intruders ranged from rock wallabies and bettongs to skinks and birds. Little penguins were recorded using burrows 27 times, while the black-footed rock wallaby was observed using wombat burrows more often than wombats – nearly 2,000 visits in eight weeks! They were even observed using the burrows to specifically avoid birds of prey.

But wombats aren’t alone in providing real estate for other species. Hopping mice, echidnas, sand swimming skinks, barking geckoes and numerous invertebrates were found using the warrens of bettongs and bilbies in arid Australia.

Anybody home?

It’s also important to recognise wombats don’t have “a burrow”.
Rather, they have multiple burrows within their home range. In fact, a 2012 study tracked one wombat to 14 different burrows.

While wombats are often regarded as quite sedentary, another study found the average home range size of common wombats is 172 hectares.




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They spend a few nights sleeping in one burrow, before moving onto another.

Since each wombat has multiple burrows, many can be vacant within a home range, and abandoned burrows are common in some areas. A 2007 study showed that even among “active” burrows (those with signs of recent use), only one in three are actually occupied by a wombat at any given time.

Australian black-footed rock wallabies often use wombat burrows as makeshift lodges.
Ken Griffiths/Shutterstock

This means, at times, other species may not need to share burrows with wombats at all. It’s vacant real estate.

So how might a wombat react to an uninvited guest? This is difficult to know, and likely depends on who’s visiting. Wombats prefer not to share burrows with other wombats, although burrow sharing can be common when wombat populations are very high in one place.

In her book Wombats, Barbara Triggs recalls a fox being chased from a burrow by an angry wombat. Meanwhile, the crushed skulls of foxes and dogs in wombat burrows suggest not all intruders are welcome.

That a suite of species use wombat burrows suggests wombats may not notice or care about squatters – so long as they don’t pose a threat. But more research is needed on the fascinating interactions that take place in wombat burrows, particularly during fire.

The battle is not over

While empirical studies are needed, the available evidence suggests wombats may well provide an important refuge for other wildlife during fire.

In any case, it’s important to recognise that surviving fire is only half the battle.

Wombats and their house guests face a medley of challenges post-fire – not least avoiding predators in a barren landscape and eking out a living in a landscape with scarce food.




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The Conversation


Dale Nimmo, Associate professor/ARC DECRA fellow, Charles Sturt University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australia’s bushfires could drive more than 700 animal species to extinction. Check the numbers for yourself



Invertebrates out greatly outnumber mammals everywhere, including in bushfire zones.
Michael Lee, CC BY-NC-ND

Mike Lee, Flinders University

The scale and speed of the current bushfire crisis has caught many people off-guard, including biodiversity scientists. People are scrambling to estimate the long-term effects. It is certain that many animal species will be pushed to the brink of extinction, but how many?

One recent article suggested 20 to 100, but this estimate mostly considers large, well-known species (especially mammals and birds).

A far greater number of smaller creatures such as insects, snails and worms will also be imperilled. They make up the bulk of biodiversity and are the little rivets holding ecosystems together.




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But we have scant data on how many species of small creatures have been wiped out in the fires, and detailed surveys comparing populations before and after the fires will not be forthcoming. So how can we come to grips with this silent catastrophe?

This native bee (Amphylaeus morosus) has been devastated by the bushfires across much of its range. It plays important roles in pollinating plants and as part of the food web, but has no common name, and its plight is so far unheralded.
Reiner Richter https://www.ala.org.au/

Using the information that is available, I calculate that at least 700 animal species have had their populations decimated – and that’s only counting the insects.

This may sound like an implausibly large figure, but the calculation is a simple one. I’ll explain it below, and show you how to make your own extinction estimate with only a few clicks of a calculator.

Using insects to estimate true extinction numbers

More than three-quarters of the known animal species on Earth are insects. To get a handle on the true extent of animal extinctions, insects are a good place to start.

My estimate that 700 insect species are at critical risk involves extrapolating from the information we have about the catastrophic effect of the fires on mammals.

We can work this out using only two numbers: A, how many mammal species are being pushed towards extinction, and B, how many insect species there are for each mammal species.

To get a “best case” estimate, I use the most conservative estimates for A and B below, but jot down your own numbers.

How many mammals are critically affected?

A recent Time article lists four mammal species that will be severely impacted: the long-footed potoroo, the greater glider, the Kangaroo Island dunnart, and the black-tailed dusky antechinus. The eventual number could be much greater (e.g the Hastings River mouse, the silver-headed antechinus), but let’s use this most optimistic (lowest) figure (A = 4).

Make your own estimate of this number A. How many mammal species do you think would be pushed close to extinction by these bushfires?

We can expect that for every mammal species that is severely affected there will be a huge number of insect species that suffer a similar fate. To estimate exactly how many, we need an idea of insect biodiversity, relative to mammals.

How many insect species are out there, for each mammal species?

The world has around 1 million named insect species, and around 5,400 species of land mammals.

So there are at least 185 insect species for every single land mammal species (B = 185). If the current bushfires have burnt enough habitat to devastate 4 mammal species, they have probably taken out around 185 × 4 = 740 insect species in total. Along with many species of other invertebrates such as spiders, snails, and worms.

There are hundreds of insect species for every mammal species.
https://imgbin.com/

For your own value for B, use your preferred estimate for the number of insect species on earth and divide it by 5,400 (the number of land mammal species).

One recent study suggests there are at least 5.5 million species of insects, giving a value of B of around 1,000. But there is reason to suspect the real number could be much greater.




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How do our estimates compare?

My “best case” values of A = 4 and B = 185 indicate at least 740 insect species alone are being imperilled by the bushfires. The total number of animal species impacted is obviously much bigger than insects alone.

Feel free to perform your own calculations. Derive your values for A and B as above. Your estimate for the number of insect species at grave risk of extinction is simply A × B.

Post your estimate and your values for A and B please (and how you got those numbers if you wish) in the Comments section and compare with others. We can then see what the wisdom of the crowd tells us about the likely number of affected species.




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Why simplistic models can still be very useful

The above calculations are a hasty estimate of the magnitude of the current biodiversity crisis, done on the fly (figuratively and literally). Technically speaking, we are using mammals as surrogates or proxies for insects.

To improve these estimates in the near future, we can try to get more exact and realistic estimates of A and B.

Additionally, the model itself is very simplistic and can be refined. For example, if the average insect is more susceptible to fire than the average mammal, our extinction estimates need to be revised upwards.

Also, there might be an unusually high (or low) ratio of insect species compared to mammal species in fire-affected regions. Our model assumes these areas have the global average – whatever that value is!

And most obviously, we need to consider terrestrial life apart from insects – land snails, spiders, worms, and plants too – and add their numbers in our extinction tally.

Nevertheless, even though we know this model gives a huge underestimate, we can still use it to get an absolute lower limit on the magnitude of the unfolding biodiversity crisis.

This “best case” is still very sad. There is a strong argument that these unprecedented bushfires could cause one of biggest extinction events in the modern era. And these infernos will burn for a while longer yet.The Conversation

Mike Lee, Professor in Evolutionary Biology (jointly appointed with South Australian Museum), Flinders University

This article is republished from The Conversation under a Creative Commons license. Read the original article.