Koala tree selection in a mixed-tenure landscape and post-fire implications

Context. The more frequent and intense bushfires predicted under climate change are likely to heavily impact koalas living inside protected areas and intact forests, which makes koala habitat in asset protection zones more important. Understanding how koalas use different habitats in a mixed-tenure landscape can inform effective conservation management. Aims. The aims of this study were to determine (1) the species and size of trees used by koalas, (2) whether choice of daytime trees was affected by available proportions of tree species and sizes in koala home ranges, and (3) whether developed land was used as frequently as native forest. Methods. Tree use by koalas was determined by radio-tracking 10 koalas for an average of 12 months and recording the species and diameter of trees they occupied. To compare the proportions of tree species used by koalas with those available, tree availability was measured using random quadrats in the home ranges of five koalas that used forested areas extensively. The habitats used by 10 koalas were classified as native forest or developed land to investigate the importance of human-modified areas. Key results. Eucalyptus punctata was a preferred tree species, but each individual used four to nine species. Tree species were not chosen solely on the basis of available proportions; some species were selected preferentially. Half of the koalas used more developed land than native forest. Koalas preferentially used trees with larger diameters than the mean of available trees, and selected larger trees in developed areas than in native forest and when re-using trees. Conclusions. Despite the higher availability of trees in protected native forest at the site, 70% of the koalas used developed land in and around asset protection zones. Koalas whose home ranges were geographically close, but had different soil types and vegetation communities, were able to utilise different tree species.