The shift around 43,000 years ago in the type of land plants found in Australia was caused by the extinction of large grazing animals, suggests an article published online this week in Nature Geoscience. The findings go against earlier suggestions that fire use by humans, who had colonized Australia not long before, caused the vegetation shift that led to the build-up of the continent’s fire-prone vegetation.
Stefan Schouten and colleagues reconstructed changes in vegetation and fire incidence between 58 and 43 thousand years ago, using indicators of plant abundance and biomass burning. They show that the abundance of the previously dominant vegetation type fell significantly during this period, coincident with a rise in biomass burning. The vegetation shift followed directly from the extinction of the Australian megafauna.