By: The Edmonton Journal
Forester Milton Davies spent an exasperating summer watching road contractors slice the roots of American elms on the boulevards throughout his neighbourhood of Queen Alexandra.
Buttress roots holding up 15-metre-tall, 10-tonne trees have been cut and left bare, delicate feeder roots that sent water and nutrients up the trunk have been torn out, all to lower the sidewalk, regrade and introduce rounded curbs for the south-side mature neighbourhood.
“The engineer wanted things pretty much flat and they dug out pretty much all the feeder roots for these trees,” Davies said, predicting fewer and smaller leaves, then dead spots in the trees. “Unless we see catastrophic failure, it will take several years before the symptoms appear. By then, they’ll be partway down the mortality spiral.”
Most of the roots of American elms are in the first 45 centimetres of soil. In Queen Alexandra, contractors often dug 20 to 30 centimetres down to regrade the land, said Davies. The trees there are 80 to 85 years old now and could live 300 to 350 years with protection.
He’s a professional forester and engineering technologist who worked for the city’s forestry department for 21 years before starting out as a private consultant. “I’m third-generation Edmontonian. This is something my grandparents insisted on in the neighbourhood. This is something that you just can’t pay money for,” he said, looking down the street at the graceful green canopy Tuesday.
“This is called a cathedral street. The trees have become massive. This is part of our heritage.”
The City of Edmonton is reconstructing roads, gutters and sidewalks in about nine aging neighbourhoods a year, re-engineering and regrading the infrastructure. Transportation officials and forestry staff work together and say they minimize damage to the trees, but not everyone agrees they’re doing enough.
Coun. Ben Henderson looked at the damage, spoke with forestry officials and said it appears the contractors should have been more careful in Queen Alexandra. He’d like to see the rules clearly spelled out, with the foresters holding more power to protect the trees.
“The trees are way too valuable an asset to lose,” he said, adding that he’ll bring an inquiry to council next fall to bring attention to the issue if needed.
Neighbourhoods with even larger trees, such as Old Strathcona, are coming up for redevelopment and the risks are significant, he said. “We’ve got some big tricky neighbourhoods to deal with.”
Bonnie Fermanuik, a city urban forester, said they have lost some trees, especially from damage during the first years of the neighbourhood reconstruction program, which started in 2009. But now they’ve started using air excavation to gently figure out exactly where the roots are running and are sometimes able to lift the sidewalk or reroute it slightly to protect some of the roots.
“We’re trying to mitigate as much root disturbance as possible,” she said. The forestry department also started watering affected trees in the neighbourhoods several times a year for three or four years after the damage.
“We found that has really helped,” she said. “The trees recover. … But if you’re damaging the roots, you’re going to lose some branches.”
Tony Sestito, general supervisor for neighbourhood reconstruction, said contractors protect the trees by leaving up to two metres of undisturbed soil around the base of the largest ones. They work with foresters who visit on-site once or twice a week and each neighbourhood has a city inspector on-site several hours a day monitoring the work.
But regrading or building a concrete sidewalk to replace the asphalt can force them to dig down 30 centimetres.
“We’re designing into these mature areas and we need to make sure the water drains off properly. There’s a lot of constraints we’re working within,” added Jeff Ward, director of neighbourhood renewal.