The fire regime

Say “bushfire” and most people picture a single catastrophe: 1983, or Cudlee Creek in 2019, a wall of flame and then silence. Ecologists reach for a different word — the fire regime — because what shapes a landscape is not one fire but the pattern of many: how often flame returns to the same ground, how hot it burns, which season it prefers, and whether a human hand lit it or lightning did. Change any one of those dials and you get a different bush.

Southern Australia’s plants were built to expect this pattern (Keeley et al. 2012). A eucalypt stripped of every leaf carries thousands of dormant buds shielded deep beneath its bark for exactly this contingency, ready to fuzz the blackened trunk green again within weeks (Burrows 2013). That is not resilience bolted on afterwards; it is a design brief written by a regime of recurring fire over deep time. A season after a burn, the Adelaide Hills feel less like a graveyard than a building site.

For tens of thousands of years before 1836, that regime included people. Aboriginal Australians burned the country deliberately and often, in cool, patchy, low-intensity fires that spent fuel in small change rather than let it bank toward a catastrophe — a practice the archaeologist Rhys Jones named “fire-stick farming” in 1969 (Jones 1969). Bill Gammage argued the whole continent was managed, district by district, on this principle; that grander thesis is contested among historians, and this book keeps only to what the plainer record will bear (Gammage 2011). Less contested is that the regime changed sharply after colonisation: the small, frequent burns stopped, fuel piled up instead of being spent, and a landscape built to expect gentle, regular fire got, on the worst days, the opposite — rare fire, but catastrophic when it came.

That is the argument modern fire management is still having with itself. Prescribed burning tries to buy back something like the old regime’s rhythm, deliberately, in the cool months, because a fire-built country cannot have fire switched off; it can only be handed the wrong tempo, or something closer to the right one. Exact intervals here are still poorly pinned down for Adelaide’s own forests — treat any single number with suspicion — but the direction of travel is not in doubt: a warming, drying Mediterranean summer is shrinking the calendar in which anyone gets to choose.