Australia Weather News

A summer of extreme weather has stoked anxiety about the planting of eucalyptus trees. - ABC

Downed trees have caused widespread disruption for thousands of residents recovering from severe storms in recent weeks, fuelling renewed debate about how to better protect communities from the elements.

As the clean-up continues, concerns around the planting of eucalyptus trees in urban areas are being voiced.

But experts have warned that, despite the hype, the risk to lives and property would be even greater if the gum trees were gone.

Anxiety understandable

Royal Botanic Gardens chief botanist Brett Summerell has noticed an increase in anxiety around eucalypts in recent months.

He told ABC Radio Sydney that fears surrounding the damage that could be caused by falling gum trees were understandable, given the extreme weather conditions over summer.

"As much as I love them, I was starting to think a little more nervously about eucalypts. So I think it's something people are thinking about," Dr Summerell said.

Eucalypts are the most common trees in Australia with up to 800 species, representing about 30 per cent of the country's vegetation.

They can grow to over 60 metres tall and have been referred to as widow makers for their tendency to drop limbs during times of stress.

Their prevalence can be a problem, especially when poorly chosen species are planted in urban areas, according to Dr Summerell.

"Certainly some of the species that we plant commonly in our urban environments, they do tend to have a shallow plate of roots," he said.

"With extended periods of drought, the abuses that we do to them when we cut into their root systems, and problems with pests, are making them more susceptible to falling over."

In recent weeks, trees with dried-out root systems that were suddenly inundated with water were the most likely to fail, Dr Summerell said.

Mixed government response

Some local governments have moved away from planting eucalypts for the benefit of public safety.

In 2004, Boorowa Council in regional NSW banned the planting of new gum trees over liability concerns.

But other governments have found that the benefits of planting trees like eucalypts outweigh the risks.

The Queensland Government examined a range of scientific evidence for a 2012 report on the assets for flood and cyclone resilience.

It found that cyclone-affected areas without trees suffered "significant damage" whereas sites with mature trees received only some damage.

"Newer suburbs suffered more damage — attributed to protection by mature vegetation in older suburbs," the report reads.

"Well-established, strong trees can trap debris and reduce cyclonic wind damage, but poor management such as lopping can weaken the tree and increase risk."

The report concluded that there was a "strong case" for better understanding and harnessing natural assets to reduce the impact of extreme weather.

Science supported

The findings are echoed by Arboriculture Australia, the national peak body for arborists.

"[In a storm] trees absorb energy from the wind, they slow it down and transfer that energy to the ground," said spokesman Mark Hartley.

"Without those trees the consequences would be horrendous.

"If we look at storm damage in Australia, trees are nothing in the scheme of things. Hail does far more damage."

Like many Sydneysiders, the second generation arborist has witnessed the destruction caused by trees downed in the recent storms.

He said it is important to remember that more people are killed each year by horses, chairs, and falling out of bed.

"The chances of being killed by a falling tree is one in five million … so if you're lying awake and thinking about the storm perhaps you should be thinking about getting a futon," Mr Hartley said.

"Most of what we are concerned about is not a reality. It's just a phobia that is irrational."

ABC