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Tall street trees in Petersham are the norm & residents benefit greatly from this

On 2nd September 2010 a news item in the Toronto Star titled ‘Tree-lined streets not worth the cost, arborists say’ caused a bit of an uproar on the net amongst people interested in trees. The article was discussing the problem of street trees in Toronto. For me it was a good read in that it showed me that problems with the management of street trees are happening elsewhere & that trees in Marrickville LGA generally get a better time of it than those in Toronto.

“You plant trees & people expect them to thrive. They don’t thrive, because they have lost 80-95 percent of their roots,” said Richard Ubbens, director of urban forestry for the city of Toronto. “These trees are in major, major shock.”

Well the first question I had was, “What happened to their roots?” but this was not answered in the article.  I’ve watched a street tree planted here by Marrickville Council staff & all the roots were planted along with the tree. The tree is still growing & didn’t go into shock even though it is in a concreted space, under an awning & the said tree lost a number of its branches.

Street trees in Toronto were described as expensive & barely contributing to the urban canopy goal because of their small size & that they die. They were also described as “really high maintenance.”

Petersham street trees

Here is a very big difference. Street trees in Toronto are cared for & watered for 2 years. Here they are watered once a week for 12 weeks.  I know for a fact Marrickville Council would be overjoyed if residents & business owners helped by watering the street tree outside.

Toronto street trees are planted into traditional holes cut into concrete & as with trees here, get as much water as they are able when it rains which is not much as most rainwater runs away as stormwater. “Above ground, trees simmer in the city heat, suffer in the smog & take in pollution. Underground, the roots compete for space & water in a concrete-laden system that simply whisks water away into the sewers.”

Toronto Tree Managers would prefer to plant trees in the city’s ravines as they mostly survive there. Although they see street trees as a waste of taxpayer’s money, they acknowledge that the streets would be bare without them.

Now they are trying to deal with the problem by establishing maintenance plans over a 10-year period that includes pruning. As well as watering the street trees regularly they feed them with compost tea (so easy to do) & mulch.

They are also trying larger pits with some pits connected so the tree’s roots can travel & also using Silva Cells where appropriate though they are an expensive option.  Silva Cells allow trees to grow deep roots & at the same time stop soil compaction & allow heavy use surfaces to be around the tree.  See –

For the Toronto Star article ––tree-lined-streets-not-worth-the-cost-arborists-say

Meanwhile scientists, planners & engineers gathered for the National Tree Symposium at Adelaide University.  They were discussing the latest methods to increase the urban tree canopy, including methods to direct stormwater to street trees rather than the age-old loss of this water down drains.

Street tree in Marrickville

Perhaps it’s the weather. Toronto has lashings of snow, while most of Australia bakes & it is getting worse. Last summer there were many heat-related deaths in Adelaide & Melbourne.  There is justified fear that summer heat-related deaths will happen again or develop into the norm because of increased temperatures due to global warming.  Tree & urban planning specialists know we need to increase the canopy as fast as we can & importantly we need to maintain it.

That street trees are only expected to last 5-10-15 years in modern-day tree management is to my mind crazy.  It’s crazy because with a few simple changes, street trees can live for decades.  We have many examples of old trees living happily across Australian cities, including throughout Marrickville LGA.

It costs money to buy trees, to plant them & to chop them down. I’ve said before trees are the only infrastructure Council has that increases in value.  We need to let them grow not only for the beauty they bring, but also because trees drop the need for power use (especially cooling), their shade lengthens the life of footpaths & roads & they have a major psychological effect on human happiness amongst many other things.   I will write about ideas that experts have to help street trees live longer in another post.




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