9 June 2023

ANU expert says eucalyptus trees aren't the 'widow-makers' we might think

| James Coleman
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gum tree in front of house

Several large eucalyptus trees in Belconnen drop their limbs during a storm in January 2022. Photo: Jess Tankard.

The government is planting 54,000 new trees across the ACT over the next two years in an effort to grow canopy to 30 per cent by 2045. But not everyone is happy with the choices.

The City Services directorate says the plantings will fit in with the designated species of the street or park in question “to ensure the look and feel of the urban landscape is retained for future generations”.

About half will be native eucalyptus trees, a figure that’s striking fear into the hearts of some Canberrans who note the genus’ reputation for dropping hefty limbs onto cars and houses at random, and becoming a “widow-maker”.

“Great to see lots of tree planting going on around Tuggeranong, however, most are gum varieties,” one resident posted to the Canberra Notice Board Group on Facebook.

“Why not plant some pretty deciduous trees, especially around schools and paths, etc, where gums can be dangerous?”

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These concerns echo those of Belconnen residents after a storm swept through on 3 January, 2022, downing trees and leaving homes without power for up to seven days. The clean-up stretched to three months.

In its aftermath, residents shared stories of being “terrified” of gum trees near their properties, while others said they had tried for months to have them removed by the government to no avail.

In September last year, a Legislative Assembly committee recommended the government “consider the appropriateness of tree species as part of future urban planting with regard to the risk of damage from severe weather events”.

“[Eucalypt] species are shallow rooted, making them more likely to fall over during storms, and are prone to dropping limbs. They are also tall growing, often overshadowing power lines,” the committee’s report read.

Pin oak plantings, Stuart Street, Griffith

Not every new tree is a eucalypt, as theses pin oak plantings in Griffith show. Photo: Ian Bushnell.

Associate Professor Cristopher Brack, from the Fenner School of Environment and Society at the Australian National University (ANU), has worked closely with the ACT Government since 1994 on choosing trees for the urban environment. He says eucalypts tick a lot of boxes.

“They work in the city, they have long life spans and they do all the things you want a tree to do in the city.”

The government considers many factors for new tree plantings, including water and nutrient availability, shading and light, safety of pedestrians, cyclists and drivers, nearby infrastructure such as underground pipes or overhead electricity cables, and environmental benefits.

According to the latest analysis, 20 of the top 50 trees chosen as suitable for Canberra’s streets are eucalypts. But Associate Prof. Brack says the native – and non-eucalypt – brachychiton populneus (commonly known as the kurrajong) still remains the number-one preference.

“It’s the single best tree we think works climate-wise and city-wise on a streetscape.”

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He says natives are often chosen over exotics for their stronger drought resistance. Compared with deciduous trees, they also don’t clog Canberra’s waterways with leaf litter and promote algae blooms further down. He puts the bad rap of eucalypts down to “confirmation bias”.

“‘Widow maker’ is an old forestry term. It’s for the guys who were felling trees and not noticing dead wood or not being very practised in how you fell a tree. It’s really not appropriate for the city.”

Associate Prof. Brack says there is no evidence in the ACT to suggest eucalypts shed more limbs than any other genus of tree.

“Most of the eucalyptus trees in Canberra have dead branches up in the permanent canopy, but they’re pretty structurally solid. The only reason they do come down is when they get damaged and rot gets in them, and that can happen to any tree.”

Autumn trees

They might look pretty but deciduous trees do make a mess. Photo: Michelle Kroll.

No matter the type of tree, they all have to contend with Canberra’s soil.

“Our soil is not very deep because there’s a lot of clay low down, so often the trees are fairly shallow rooted. In general, though, the eucalypts we have planted here are generally more stable than other species.”

In the end, Associate Prof. Brack says the deciduous/native debate is rooted in personal preference.

“People either love the native trees because they don’t shed leaves or they love the exotics because they don’t shed large ribbons of bark. It’s a personal preference thing to an extent.”

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how much do they cost drain blockage ? will the interfere with solar access. or street illumination at night ?

Native trees don’t shed leaves? He should come see my gutters 2 weeks after I’ve cleaned them.

“According to the latest analysis, 20 of the top 50 trees chosen as suitable for Canberra’s streets are eucalypts”

I guess the eucalypts rank from number 31 to 50!

I love eucalypts out in the landscape, away from housing and roads. They are far too dangerous to have them in built up areas. Too many people have been killed as a result of the trees randomly dropping branches ore being blown over by strong winds.

Much as I love our native trees, they don’t provide the same level of shade as a deciduous. And don’t let in the sun in winter. Just how wonderful is the canopy of trees outside the national library.

This article doesn’t fit with what I observed after the Belconnen supercell storm in 2022. Eucalypts were down all over the place, including on the oval next to Cook shops. I understand they created a big hassle for Evoenergy falling on power lines. Two went through roofs in Wybalena Grove, causing damage worth tens of thousands of dollars. I bet the insurance industry won’t agree with what is expressed in this article.
Another person commented to the Legislative Assembly inquiry into the Belconnen supercell storm as follows: I live in [redacted] and this issue with the number of mature trees in the neighbourhoods necessarily means that old and shallow root trees will continue to fall taking out not just the power lines but homes as well. It seems to be the nature of eucalypts and pines to have shallow roots and when big rains and winds come, they are prone to falling.54

Having lived with 3 street gum trees for 20 years they were a curse. Dropping leaves and branches all year round and in summer it’s bark. This all went into the guttering of the house and car, there is also the sap. I have since moved and now have a lovely deciduous tree out front that drops it’s leave once in autumn….. bliss 😊

HiddenDragon7:27 pm 11 Jun 23

“Most of the eucalyptus trees in Canberra have dead branches up in the permanent canopy, but they’re pretty structurally solid. The only reason they do come down is when they get damaged and rot gets in them, and that can happen to any tree.”

I am familiar with a large eucalyptus which has dropped three living branches – each with healthy foliage on it and no signs of decay or other problems such as epicormic growth. One of the branches came down in high winds, the others fell in benign weather.

Each of the branches would have been large enough to kill or seriously injure anyone unfortunate enough to have been beneath it when it fell, or to have caused serious damage if it had fallen on a car or a house.

The tree has been inspected by one of the most experienced and well-qualified arborists in Canberra who pronounced it to be in rude good health and in no need of trimming or any other treatment.

I love the beauty of native eucalypts, wattles, bottle brush, grevilleas, flannel and wax flowers in bush settings, but will always seek out the European trees for cool shade when walking in summer.

These choices sound like an ACT government that is just keen to reduce the costs of street maintenance, with not concerns about the problems this creates.

Eucalypts create fire risks that deciduous trees do not.

Many old deciduous trees have coped with the drought better than have many eucalypts, perhaps because they are deep rooted and so can access ground water.

We desperately need to cool our city in summer to prevent the heat island effect as buildings with more glass, concrete, asphalt dominate our city, replacing parks, ovals, sports grounds and other green spaces. There is nothing like the dense deep green shade of deciduous trees to do this. Additionally, they allow the sun through in winter to warm the city after losing their leaves until Spring. The older parts of Canberra are cooler in summer than newer areas as a result of their European plantings and greener landscapes.

The preferences, observations and real world experiences of numerous residents, across numerous suburbs, should always be more persuasive than the bleatings of another grant chasing Associate Professor.

Stephen Saunders1:52 pm 11 Jun 23

Starting them young, Australians are trained to distrust the native flora, and to prefer this Europhile twaddle. Our Bush Capital and Botanic Gardens, are easily cancelled out, by the lucrative Floriade and Arboretum “attractions”. Thanks for nothin’, Jon Stanhope.

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