Tree health in limbo as climate change worsens

Drought followed by storms spell disaster for Vancouver's trees

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By Nicolette Colosimo

As climate change is increasingly damaging the health of trees in Vancouver, Langara College is trying to manage fallen trees and power outages on its campus.

Droughts and storms have weakened trees in Vancouver. And when a violent storm moved through the Lower Mainland on Nov. 9, many frailer trees toppled — disrupting powerlines and forcing the closure of Langara College.

Dwayne Doornbosch, director of the facilities department at Langara, said that due to the summer drought earlier this year, his team has been more aggressively pruning and walks the grounds daily to keep a close eye on the trees on campus.

“We do regular assessments of all trees on campus with an arborist. We then prune or cut trees down accordingly,” Doornbosch said.

Managing electrical trouble

Weakened trees forced BC Hydro to accelerate its vegetation management system to keep up with climate change and protect its electrical infrastructure. According to its September 2021 report, the electricity provider is expected to manage 6,900 hectares over the following year, up from 5,000 hectares.

BC Hydro spokesperson Susie Rieder said the storm caused power outages to about 20,000 customers.

“Power went out when three power poles were broken on two separate transmission circuits due to falling trees and branches that were damaged by the wind,” Rieder said.

She said adverse weather and fallen trees cause almost 60 per cent of outages in B.C. Drought-weakened trees coupled with stormy weather could result in more power outages, she warned.

“Really dry soil can uproot trees, especially with windier conditions,” she said. “And trees that are dying or diseased because of the drought can also pose a challenge.”

The precursors

Norm Oberson, an arborist at Arbutus Tree Service, said extreme temperature can trigger a series of events, which can start when extreme temperature first stresses the tree.

“The tree survives, but it’s stressed,” Oberson said. “What happens is an insect attacks, or a bacteria or fungus attacks, because the tree’s defence system has been weakened.

“So, it’s susceptible to attack from other living or environmental things.”

Oberson suggests installing steel cables to add supplemental support to trees and avoiding removal.

“You assess a tree and only remove a tree as a last resort.”

The map outlines the number of street trees across South Vancouver neighbourhoods.

 

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