Designing food and habitat trees for urban koalas: Tree height, foliage palatability and clonal propagation of Eucalyptus kabiana

Abstract

Koalas are iconic Australian tree-dwelling marsupials that are classified as vulnerable because of threatening processes that include urban development, habitat fragmentation and inbreeding. Koalas eat the leaves of specific eucalypt trees but urban planners and landowners often prefer to plant smaller trees that pose less risk from falling limbs. We have conducted a long-term project to develop shorter koala-food trees for planting in parklands, schools, streets and gardens. We identified a little-known and geographically-confined species, Eucalyptus kabiana, that had potential for urban plantings. We assessed the height of E. kabiana trees in cultivation, determined whether their foliage was palatable to koalas, and compared the amenability to vegetative propagation of E. kabiana with that of an extensively-propagated related species, E. tereticornis. Cultivated E. kabiana trees were short, reaching around 3–5m height after 6 years. Their foliage was highly palatable to koalas, and their cuttings proved to be amenable to propagation. Average rooting percentages for E. kabiana cuttings were 31–46%, similar to values obtained with E. tereticornis cuttings. Over 600 E. kabiana trees have thus far been distributed for planting in wildlife corridors, parklands, schools and gardens. The planting of more koala-food trees will help to alleviate the risks of inbreeding faced by koala populations in fragmented urban landscapes. School plantings also provide opportunities for students to learn about and interact with organisms such as koalas that inhabit the Eucalyptus trees.