Something went missing: cessation of Traditional Owner land management and rapid mammalian population collapses in the semi-arid region of the Murray–Darling Basin, southeastern Australia

Abstract

The nineteenth century mass mammal extinctions in the semi-arid zone of the Murray‒Darling basin, southeastern Australia, are examined in the context of prior traditional land management. A model of grassland dynamics reveals a multi-trophic level productive pulse one to five years post-fire, followed by senescence and increasing flammability. Traditional Owner patch burning of grassland optimized human and mammalian food (including tubers, seeds and fungi) and decreased fire risk. Over at least 40 000 years, the persistence and abundance of fauna responded to this energetically closed self-reinforcing management. In 1830, depopulation (disease, massacres and displacement) effectively ended traditional management, an ecologically traumatic event that extinguished these productivity pulses. Associated mammal populations of c. 20 species collapsed, and all eco-engineering and mycophagous species, such as bilbies, bettongs and bandicoots, rapidly disappeared. Traditional land management increased productivity, habitat heterogeneity and reduced wildfire risk, underpinning mammal abundance. This has remained unrecognized by most mammalogists and land managers. Blaming extinctions predominantly on the additions by Europeans (introduction of ungulates, feral grazers and predators etc.), disastrous as they were, fails to acknowledge the initial cause of rarity, i.e. loss of productivity, habitat and niches when traditional management was subtracted from country. As ecosystems continue to degrade, understanding the primary cause is fundamental to improved management. Although too late for extinct species, respect for, and inclusion of, traditional land management knowledge provides a direction for future land management.