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Fire in Australia is a symptom of a degraded ecosystem (commentary)

  • Ancient, human-induced climate change in Australia precipitated an ecological catastrophe, turning a rainforest continent into desert.
  • A compromised ecosystem where biological decomposition of plant matter is insufficient renders an imbalance between photosynthesis and respiration, leaving fire as the only way to balance the carbon equation.
  • Steps towards ecological regeneration will have far-reaching and exponential benefits to environment and society and provide natural fire mitigation.
  • This post is a commentary. The views expressed are those of the author, not necessarily Mongabay.

Fire is not natural to Australia, as incomprehensible as that may seem today.

When humans first landed on the northern shores it was a very different continent. Most of Australia was a biodiverse rainforest inhabited by dozens, if not hundreds, of species of marsupial, reptilian, and avarian megafauna, such as the famous hippopotamus-sized Diprotodon. The enormous ‘biotic pump’ of the interior’s forests — a photosynthetically-driven transpirative engine — sucked moisture inland hundreds of kilometres from the Indian Ocean where masses of bacteria released by transpiring plants condensed that moist air into rain.

These forests, which were ten times more ancient than the Amazon and survived climatic fluctuations over more than 100 million years, then suddenly disappeared. The megafauna, along with a plethora of plant and smaller animal species, were collateral damage to the human-induced ecosystem destruction and consequential continent-wide climate change, disappearing along with their former habitat and food sources. Only a few small remnants, often rejected as human food due to their too-high protein-to-fat ratio, such as the kangaroo and emu, managed to survive as the pyrophytic grasses, eucalypts, and acacias took over.

The Amazon is, perhaps, an apt and timely comparison to draw with Australia. It is one of only three places on the planet, along with the Congolian rainforest and the Siberian taiga, where forests, not deserts or grasslands, exist more than a few hundred kilometres from an ocean. The Amazon creates its own rain via its transpiration-driven ‘flying river.’ It is a hotspot of biodiversity and currently faces the same dire threat through deforestation, fragmentation, and coastal divorcement that likely led to the ecosystem demise and desertification of Australia. Indeed, rainfall in the Amazon has already significantly diminished.

At some point, Australia’s first peoples, through the use of fire and other management practices, broke the biotic pump, stopping the rains and turning the continent into a desert. The highly weathered, low-fertility soils typical of tropical rainforests are notorious in Australia and testament to its ‘natural’ environment.

Unlike other ecosystems, rainforests hold most of their nutrients in the biomass and depend on rapid nutrient cycling for their high productivity. Once the forests died the nutrients were simply washed away or lost to wind and fire.

Bushfire smoke over the Sydney Opera House and Sydney Harbour Bridge on December 29, 2019. Photo by Nick-D, licensed under CC BY-SA 4.0.

Despite their ancestors precipitating an ecological catastrophe, Australia’s indigenous peoples developed an inseparable and respectful relationship with country that is absent in today’s new culture. A continent-spanning management system created specific mosaics to provide abundance, with a critical aspect being what is generally referred to as ‘firestick farming.’ New management over the past 200 years, however, has resulted in exponential degradation of what remains of Australia’s landscapes and will continue to make worse aridification, soil depletion, biodiversity loss, and ecosystem simplification. This summer’s conflagrations are the most recent incarnation of that management regime and display a lack of understanding of the fires as principally an ecological issue above all.

To begin with, fire is not a natural phenomenon in any environment, at least beyond minor, localized, and infrequent exceptions (such as lightning strikes). And, in order for there to be fire, there must be fuel to burn and conditions must be conducive. In all cases, fire consumes organic materials produced from carbon fixation via photosynthesis — think wood or grass. Photosynthesis is the production of sugar and oxygen from water and carbon dioxide, with sunlight, in no short supply in this sunburnt country, as the catalyst. Burning is, essentially, the reverse of photosynthesis, and can happen biologically through respiration, such as when we ‘burn’ energy during exercise, or chemically with fire as its catalyst.

A plant then has two general options of where to direct its photosynthetically fixed carbon — as growth into its biomass or as energy currency exchangeable with soil microorganisms for nutrients, water, and other services. In a healthy ecosystem, a large proportion of fixed carbon can flow via this second route, the ‘liquid carbon pathway,’ providing food for soil life. Indeed, up to 30-40% can be rapidly humified, ultimately providing soil structure and soil organic matter. The resulting dark, crumby soil — which every gardener instinctively prizes — imparts fertility and resilience to an ecosystem and acts like a sponge to soak up and hold water, thus mitigating both drought and flood.

But what of the fate of the carbon incorporated into plant biomass? For one, plant roots will eventually enter the soil carbon equation as they die. As for the above-ground biomass — stems, leaves, branches, fruits, nuts — three general fates are possible. The first two, predominating in healthy ecosystems, are that plant biomass is either eaten by animals or decomposed by organisms like fungi and worms. Animals eat and incorporate this carbon and nutrients into their own bodies and defecate and urinate and eventually die, providing a beautiful means for ecosystem nutrient-cycling from plants through animals to soil and, via the soil microorganisms, back to plants. Fungi and other decomposers subsequently recycle, provided sufficient moisture availability, what did not pass through an animal’s gut.

The Australian ecosystem, however, has become simplified and degraded, where an unbalanced build-up of plant biomass above ground becomes inevitable, leading to the third possible fate: fire. In fact, fire becomes the only alternative to recycle organic carbon in the current Australian context, where herbivores and favourable conditions for biological decomposition have been removed.

To make matters worse, ecosystem simplification exponentially compounds negative effects. For example, vegetation loss lowers rainfall and reduces food for animals and soil microorganisms, reducing mineral and carbon cycling. Soil carbon is oxidized (and released as carbon dioxide), diminishing water-holding and nutrient-holding capacities, lowering forage and browse quality, and increasing fibrous material to encourage fire. Fire decreases plant density and diversity and burns off surface litter, exposing bare ground to erosion. Bare ground becomes capped and impenetrable to rain while increasing evaporation and surface temperatures.

But, given suitable management, ecosystem regeneration is also an exponential cascade of positive outcomes. Greater vegetative productivity and plant cover builds soil organic matter, capturing and holding more water and nutrients, attracting more rain, and cooling the land surface. Higher nutritional vegetation and water availability boosts animal performance and provides favorable conditions for fungal decomposition, providing natural fire mitigation. More animals speed up nutrient cycling and provide the ‘pruning’ effect to invigorate plant life. The resulting biological synergies will provide a wetter, cooler, more productive, healthier, and more beautiful Australia for human habitation.

How will this be brought about? Perhaps the only certainty is that there will be no single formula, but rather that context will dictate what actions are to be employed according to individual and collective future visions and, critically, to what the land and its ecosystems are trying to tell us.

What it will take is that Australians yearn to become native to place, developing deep love and connection. In one of the most urbanized and technological societies, disconnected in large part from the natural world, this may be not be easy — but it is necessary. It will also be necessary to relinquish such ideologies as resistance to non-native species, pure wilderness, and animal sacredness. Likewise, many relationships may require reframing, such as to government, to common and crown lands, producer-consumer, urban-rural, and human-animal. The ecosystems or societies needn’t look like what is current nor past, but they can be highly functional, beautiful, and fulfilling.

Countless specific examples demonstrate ecosystem regeneration across all landscapes and climatic zones throughout the world, this southern land portraying many. Though growing in number, they sadly currently account for only a tiny portion of land under management. With a focus on building soil, maximizing solar energy capture — i.e. photosynthesis, speeding nutrient cycling, storing ‘green water’ in soils, incorporating appropriate animal management in landscapes, and fostering biodiversity — Australia will be well on the path of rejuvenating its ecosystems. With an ecological literacy and love for country, this fire-ravaged, impoverished land, through ecological restoration, can be turned into a resilient, productive, biodiverse, safe, and nourishing home.

Bush fire in central Queensland, Australia in 2010. Photo via Wikimedia Commons, licensed under CC BY-SA 3.0.

Shane Emanuelle works as a research scientist in the fields of botany and biochemistry. He is currently preparing to transition to becoming a regenerative farmer.

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