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Published: 28 July 2014

Tree grafting a way to bring koala habitat to urban areas

Tree species eaten by koalas are generally unpopular with both urban landowners and councils due to falling limbs and larger sizes. Grafting these species to smaller trees may boost koala forage and habitat in urban areas.

Grafting eucalypt species could result in smaller koala feed trees that do not drop limbs.
Grafting eucalypt species could result in smaller koala feed trees that do not drop limbs.
Credit: Thinkstock

After a series of trials, researchers from the University of the Sunshine Coast have found at least one grafted combination that could provide a valuable habitat tree for koalas and other fauna in urban areas, according to a paper published in the Australian Journal of Botany

‘We aimed to develop shorter koala trees for subtropical urban areas by using related short species as dwarfing rootstocks for tall species that are eaten by koalas’ says the paper’s lead author Stephen Trueman.

The koala is classed as vulnerable in Queensland, NSW and the ACT where their habitat is increasingly fragmented through urban development. Other threats to koala populations include disease, inbreeding, dog attacks, fire, drought and being hit by a car.

Koalas in urban and peri-urban areas are often forced out of habitat by development. Local councils are beginning to see an urgent need to revegetate urban areas with koala food and habitat trees.

‘The ideal koala food and habitat trees for planting in gardens and residential streets would be small, safe, and palatable to koalas’ says Dr Trueman.

After testing 14 graft combinations, they found one that was most successful. When grey box (Eucalyptus moluccana) was grafted to blue mallee (Eucalyptus behriana) the height of the tree was reduced from around 10 metres to 4 metres. There was a survival rate of 40% in the trial that may be improved in an urban setting.

Even though this research is now over and these trees are not yet available, the researchers hope that in the future grafted trees could be valuable habitat trees for koalas and other fauna in urban areas.

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