Page 964 - Week 03 - Thursday, 30 March 2023

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exotic invasive species like ornamental pear, Chinese elm and green ash. These species are known to be invasive, and they are documented to be “sleeper weeds”. Will you be revising this list?

MR STEEL: I thank the member for her question. From time to time we do revise the planting lists. We have done that recently on climate grounds—looking at what particular tree species will survive in the hotter and dryer climate we expect to have in the future with climate change in our region. The municipal infrastructure standards species list has as wide variety of trees that are listed that can be planted at different locations that are appropriate for the location.

Transport Canberra and City Services urban treescapes unit selects the most appropriate tree species to plant for each individual planting site. Factors considered include: the amount of available space for mature trees; the growing conditions and microclimate; the growth habit of a species and proximity to other types of infrastructure; the potential habitat and resource benefits; how to best maximise shade and cooling; the existing or desired character of a place; and how the place is used by people.

They also give very careful thought to the ecological benefits of species selected for planting and the important role of the government’s tree planting program to support and provide habitat and food resources, and to enhance biodiversity in the urban environment. Around 50 per cent of all the trees ordered are native species, many of which are endemic to our region and can tolerate Canberra’s hot and dry summer climate.

They also look at flowering and the flowering benefits of those species as well, particularly for pollinators. Many of these trees, including eucalypts, flower and provide food for birds and other pollinators. Trees that will eventually develop hollows are also prioritised for planning in open spaces. We are not simply limited to exotic species. It really depends on the location.

MS CLAY: Why do we have exotic invasive species on this list?

MR STEEL: I thank the member for her question. I know there are strong views both for and against exotic trees. I get tagged most days by those who do not want to see any new native trees planted in Canberra at all. I disagree with that view. A balanced approach sees both exotic and native species planted. As I just described before, we are doing some of that to respect the cultural heritage of some of our important places in the capital as part of major projects like light rail on Commonwealth Avenue.

We have, as I have said, reviewed the municipal infrastructure standards for plant species, and that has included the removal of some invasive species. During the last comprehensive update in 2019, based on advice, we did remove declared pest plants from the list. In some species the male version of the species may have a different effect than the female version of the plant. That is particularly the case with the Chinese pistachio, which I know well because I have three at my house. We know that TCCS only plants the sterile male form of that species, so there is care taken to make sure that the right tree is planted in the right location.


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