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The true impact of the Australian bushfires

  • Published at 10:55 pm January 19th, 2020
Australia - Wollemi park
Reuters

It is crucial that governments and land managers around the world take sensible decisions that will build resilience into ecosystems

The sheer scale and intensity of the Australian bushfire crisis have led to apocalyptic scenes making the front pages of newspapers the world over. An estimated 100,000sq-km of land has burned since July 1. At least 28 people have died. And over a billion animals are estimated to have been killed to date. Of course, the actual toll will be much higher if major animal groups, such as insects, are included in these estimates.

The impacts of climate change should be abundantly clear. 

It’s true that wildfires naturally occur in many parts of the world, and benefit plants and animals in ecosystems that have been uniquely shaped by fire over evolutionary time. But make no mistake, the scientific evidence shows that human-caused climate change is a key driver of the rapid and unprecedented increases in wildfire activity. 

Out of control

And it’s unclear how much the natural world can tolerate such dramatic disturbance. Wildfires are increasing in severity around the world. The Australian bushfires are larger than some of the deadliest recorded. Incidences are also increasing in ecosystems where wildfires are uncommon, such as the UK uplands.

Unsurprisingly, given the shocking numbers of animals that must have perished as a result of these wildfires, many are questioning whether burned ecosystems can recover from such dramatic losses of biodiversity.

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 assessed species are threatened with extinction.

But to establish the true ecological costs of wildfires it is important to consider biodiversity in terms of networks, not particular species or numbers of animals.

All species are embedded in complex networks of interactions where they are directly and indirectly dependent on each other. 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.

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.

I have studied and recently published research about the loss of plants and animals due to wildfires in Portugal, using new methods in ecology that can examine the resilience of ecosystems to species extinctions.

Our study looked at the impacts of a large wildfire in 2012 on one of the many ecological interactions that keep ecosystems healthy – insect pollination. We examined the responses of moths, which are important but often overlooked pollinators, to wildfire by comparing those we caught in burned and neighbouring unburned areas. 

We then used these networks to model the resilience of the ecosystem more generally. We found that burned areas had significantly more abundant flowers but less abundant and species-rich moths. The total amount of pollen being transported by the moths in burned areas was just 20% of that at unburned areas.

Although the study was only a snapshot in time, we 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 in Australia following the devastating 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.

Over 45 years ago,  American evolutionary ecologist and conservationist Dan Janzen wrote: “There is a much more insidious kind of extinction: The extinction of ecological interactions.” We should all be concerned not just about the loss of animals, but about the unravelling of species interactions within ecosystems on which we all depend for our survival. 

Darren Mark Evans is Reader in Ecology and Conservation, Newcastle University. A version of this article was previously published in The Conversation UK and has been published under special arrangement.