Shrub cover declined as indigenous populations expanded across southeast Australia

Wildfires in forests globally have become more frequent and intense due to
changes in climate and human management. Shrub layer fuels allow fire to
spread vertically to forest canopy,  creating high-intensity
fires. Our research provides a deep-time perspective on shrub fuel loads
in fire-prone southeastern Australia. Comparing 2,833 records for
vegetation cover, past climate, biomass burning, and human population size
across different phases of human occupation, we demonstrate that
Indigenous population expansion and cultural fire use resulted in a 50%
reduction in shrub cover, from approximately 30% from the early-mid
Holocene (12-6 ka) to 15% during the late-mid Holocene (6-1 ka). Following
British colonization, shrub cover has increased to the highest ever
recorded (mean of 35% land cover), increasing the risk of high-intensity
fires.