Bushfires: who really are the arsonists?
Australian biosphere has recently seen the worst of times. Unprecedented number of lives has been affected. Institutions have been shaken during the holiday season. Policy makers, administrative bodies, climate change lobbies, education institutes, healthcare providers, business houses — all had to consider the catastrophe on a scale they were not prepared for. A bit of blame game is not unexpected in the circumstances.
Many point finger at (human) arsonists. Surely they exhibited inhuman behaviour during tragic times. But a study by the media house ABC suggests that most fires started because of natural causes which made me take a closer look at the problem.
If forests are the crime scene, the usual actors there are plants and wild animals. Let’s put the potential human arsonists aside for now. Plants and wild animals interact with each other quite a lot. A lot more than what is perceived by the layman. Their survival and reproduction depend on contributions from each other. Fundamentally plants want the motile animals to do transportation on their behalf and animals want to use plants to draw energy. This give and take requires them to communicate somehow which they do mainly using signals in the form of visual and olfactory cues.
Back to fire, let’s consider one predominant group of actors — forest trees, particularly the eucalyptus types. Eucalypts are known to survive fire, even alleged to promote fire because of presence of oil glands in leaves and of dry barks that they shed regularly. Heck, some of them need fire to open up the hard wooden capsule and thus enable seeds to germinate. Many eucalypts are anyway capable of resprouting from buds at the stems or lignotubers at the base of the trees after the fire settles. They had learnt to adapt to fire at least 50 million years ago. This method of regeneration is thought to give them advantage in cornering the scarce forest nutrient resources as the competitive undergrowth species get lost.
The other advantage of fire to eucalyptus arises from the falling of innumerable seed capsules on the ground at once which could bring up a new generation of trees in the aftermath of the fire. This however is also a great opportunity for seed predators such as ants. They get to feed on the bounty of seeds on the ground that wouldn’t have fallen in such numbers if not for the fire.
Basically then there are two beneficiaries of a bushfire. The eucalypt like fire adaptive trees known in scientific lingo as pyrophytes who get the entire forest plant biosphere to themselves with most competition reduced to ashes. And the specific ants who feed on the heap of seed capsules that land on the ground as a result of the fire. In a typical crime investigation, suspicion usually falls on beneficiaries. We may then be inclined to blame the eucalypts or the ants for the fire. But how the hell can they light a fire?
The eucalypts at least have the required provisions for fire. There is fuel in the form of dry barks and oil which makes inflammable gas when heated. Oxygen is there everywhere. So is heat. All that is needed is ignition — the spark. Are the trees somehow capable of producing the spark? Or the ants in isolation or in collaboration with the trees? We know of light producing plants and animals. Is the idea of spark-generating organisms far-fetched? I have read about one species of ants which can damage electric cables and cause short circuits. Or is there spontaneous combustion in high heat seasons? Or maybe it is just lightning which is commonly held as a natural cause of bushfires.