The sheer scale and intensity of the Australian bushfire crisis have led to apocalyptic scenes like the image above making the front pages of newspapers worldwide. An estimated 10 million hectares (100,000 sq km) of land have burned since July of 2019. At least 28 people have died. And over a billion animals are estimated to have perished to date. The actual loss of life will be much higher if major animal groups, such as insects, are included in these estimates.
The impacts of climate change and the consequences of the increasing occurrences of extreme weather events on all life should be abundantly clear now. People finally seem to be taking this seriously, but there is an unhealthy opinion about the “naturalness” of wildfires. Some are still questioning the role of climate change in driving the Australian bushfires.
Its a fact that wildfires are natural to many parts of the world, and many plants and animals benefit owing to the evolution of their ecosystems to accommodate this. And humans have been using fire to manage/control ecosystems for thousands of years. The Aboriginal people have traditionally used techniques to mitigate and prevent bushfires that should be a lesson here.
But make no mistake, scientific evidence shows that human-caused climate change is a key driver of the never-before-seen increase in the frequency of wildfire activity. What is most worrying is the extent to which this is hindering the resilience of ecosystems across wide regions and in this case, continents. Yes, it is plausible to expect most plants and animals that have adapted to fire will recover. But the ecological bill of such colossal, high-intensity and repetitive wildfires on ecosystems could be monumental.
Out of control
It’s unclear how much the world can tolerate such dramatic disturbance to the natural order. Wildfires are increasing in severity around the world. The ongoing Australian bushfires are larger than some of the deadliest recorded. This is causing an increased occurrence of wildfire incidents in regions like the British uplands, not particularly prone to them. Not to mention the widespread deliberate burning of areas of high conservation value for agriculture, as has been recently reported in large parts of the Brazilian Amazon for beef production and in Indonesia for palm oil production.
Given the shocking numbers of animals that must have perished as a result of these wildfires, its unsurprising that many are questioning whether burned ecosystems can recover from such massive loss of biodiversity. In Australia, some estimate that the fires could drive more than 700 insect species to extinction.
The world’s biodiversity is already severely struggling – we are in the midst of what scientists describe as the sixth mass extinction. A recent report has highlighted that about a quarter of species assessed are on the verge of extinction. Australia already has the highest rate of mammal loss anywhere in the world, an indication that the already delicate ecosystems that might struggle to recover in a warming, fire-prone world, let alone function.
Animals affected by the Australian bushfires, such as koalas, have been expressed by conservationists. The outlook for many of the already critically endangered species is not clear. But to establish the true ecological costs of wildfires it is important to consider biodiversity in terms of networks and ecosystems, not individual species or their numbers.
All species are embedded in complex networks of interactions where they are directly and indirectly dependent on each other. This is the textbook definition of an ecosystem. A food web is a good example of such networks. The simultaneous loss of such large numbers of plants and animals could have cascading impacts on the ways species interact – and hence the ability of ecosystems to bounce back and properly function following high-severity wildfires.
A fragile system
And so it’s key that we consider biodiversity loss due to wildfires in terms of entire networks of interacting organisms, including humans, rather than simply one or two charismatic animals. Darren Evens recently published his research about the loss of plants and animals due to wildfires in Portugal (similar to the Australian wildfires), using new methods in ecology that can examine the resilience of ecosystems to species extinctions. His team found that networks of interacting plants and animals at burned sites became fragile and more prone to species extinctions.
Their study looked at the impacts of a large wildfire in 2012 on one of the many ecological interactions that keep ecosystems healthy – insect pollination. They examined the responses of moths, which are important but often overlooked pollinators, to wildfire by comparing those caught by them in burned and neighboring unburned areas.
By collecting, counting, and identifying the thousands of pollen grains they were carrying, they were able to decipher the plant-insect network of interacting species. In this way, Darren Evans’ team made it possible to examine not only the responses of the plants and animals to wildfire but crucially the impacts on pollination processes.
They then used those networks to model the resilience of the ecosystem more generally. They figured that burned areas had significantly more abundant flowers (due to a flush of plants whose seeds and roots survived in the soil) but less abundant and species‐rich moths. The total amount of pollen being transported by the moths in burned areas was just 20 percent of that at unburned areas.
Subsequent analysis revealed important differences in the way these species interacted as a result of the wildfire. Although the study was only a snapshot in time, they were able to show that plant-insect communities at burned sites were less able to resist the effects of any further disturbances without suffering species extinctions.
And so as people start rebuilding their homes, livelihoods, and communities following the devastating Australian bushfires, it is crucial that governments and land managers around the world take sensible decisions that will build resilience into ecosystems. To do this, ecological interaction networks need to be considered, rather than specific species. Cutting-edge network approaches that examine the complex ways in which entire communities of species interact can and should help with this.
Over 45 years ago, the American evolutionary ecologist and conservationist Dan Janzen wrote:
We should all be concerned not just about the loss of animals, but about the unraveling of species interactions within ecosystems on which we all depend for our survival.