Koala forest habitat recovery varies with fire severity

The koala (Phascolarctos cinereus) is at risk of extinction in the wild as a result of ongoing habitat loss due to clearing, and extreme weather events including fire. In 2022 the Australian government upgraded the conservation listing of the koala from Vulnerable to Endangered. In late 2019 and in 2020 Australia experienced widespread severe wildfires and many threatened species were adversely affected. A 230 hectare forested property with known koala habitat near Crows Nest, Queensland, Australia, was surveyed three months after a wildfire in November 2019, to assess impact, and then annually for three years to assess recovery. The most resilient tree species and forest types were identified to assess koala habitat robustness. Our fire severity scale classified impacts to forest types and tree species using trunk scorch height, crown scorching, crown loss, and tree mortality. Subsequent surveys classified recovery by assessing epicormic shooting, coppicing, seedlings, sapling regrowth, and tree survival. Fire promoted epicormic shooting along tree stems, but at extreme fire severity, coppicing from the base was the dominant response. Moderate and high fire severity was tolerated by most preferred koala tree species, but tree mortality increased significantly with extreme fire severity. The most fireresilient of these koala habitat tree species was Eucalyptus eugenioides, which displayed significant epicormic shooting at moderately high, and high fire severities, and significant coppicing at high fire severities. The dominant forest type in the study area is characterised by this tree species, and so may be an important factor if selecting conservation areas in this region for koalas and other arboreal mammals.