Offering lush leaves in the spring and gorgeous golden colours in the fall, poplar trees can be found lining the sidewalks of some of Calgary’s oldest communities. But a couple of councillors say that they need to go, and that it should be on the city’s dime. 

Ward 10 Coun. Andre Chabot, and Ward 14 Coun. Peter Demong are expected to present their Notice of Motion on July 22, which will ask city administration to accelerate the removal of problematic poplar trees city-wide.

The motion cited the City of Calgary’s urban forestry unit, which found that over 4,000 public poplar trees warranted removal.

Coun. Chabot said that the tree roots are cracking the sidewalks and that this, along with hefty branches, is a risk to residents—especially those with limited mobility.

“It’s also a bit of a hazard,” he said. 

“Some of those poplars have some really big branches…so heavy they crush cars, and it could actually hurt people as well.”

However, because the trees situated beside sidewalks are under the city’s jurisdiction, residents who move forward with the unauthorized removal of public property trees are subject to receiving upwards of $500 in fines.

Under the City of Calgary’s Poplar Removal Policy, residents can request the removal of a public tree after collecting the signatures of 20 of their neighbours. Once complete, the cost for extracting and replacing the tree is billed to the homeowner.

Coun. Chabot said this is unacceptable. 

“I don’t see how the city’s error in the past on policy should somehow be the responsibility of the adjacent homeowner,” he said.

“This should be strictly a city-borne obligation.”

Why were poplars planted in the first place?

Arborist and former urban forestry coordinator for the city, Russell Friesen, said that between the 1960s and ’80s, developers aimed to make “instant communities,” and that the fast-growing hybrid poplars were the way to go. 

At that time, the city bylaw permitted planting within 3 metres of the sidewalk, and building homes on top of compacted soil was common practice.

In neighbourhoods like Lake Bonavista, Friesen said that both factors have aided in deteriorating nearby infrastructure. 

“Compacted soil inhibits tree root growth,” he said.  

“Doesn’t matter if it’s a poplar, elm, or whatever species it is… communities were built less favourable for tree planting.”

Today, poplars make up approximately 19 per cent of all of Calgary’s public property trees. Coun. Chabot said that the city is hesitant to remove them because of its goal to increase the tree canopy to 16 per cent coverage by 2050. 

“The city is reluctant to remove any of those trees, even though they’re breaking up sidewalks, because they’re healthy,” said Coun. Chabot. 

“Why do we have to wait until it dies before we can replace it?”

Calgary Climate Hub member Heather Addy said that, as much as the invasive roots of poplars can be dangerous, they provide more positives than negatives, and that chopping down perfectly healthy trees would be a disservice.

“If we’re removing the big mature trees, those are the ones that give us so many benefits of the canopy,” she said. 

“If we’re replacing them with smaller stature trees, those trees will be slower growing, probably, so it’s going to be decades before we get the canopy benefit.”

Poplars not the problem, says arborist

Addy said that navigating the problem of invasive roots is nothing unique to Calgary. But what is unique, she said, is how the climate tends to get minimal water apart from periodically heavy rainstorms in the summer months. 

“Calgary, being a prairie city, is a challenging place for a tree because we don’t get the rainfall that other cities do, so water is going to be limiting a lot of trees,” she said.

However, Friesen said that poplars—specifically the native type—tend to thrive here due to how the roots search for water when needed. Meaning, the trees do not have to rely on consistent watering to prosper. 

He said that a misconception about trees is that the roots grow straight down, when in reality, they grow horizontally from the trunk. As they look for nutrition, Friesen said it’s inevitable for the roots to impact structures, and that the problem lies in the way sidewalks are built. 

“If you have a heavier, denser sidewalk, perhaps with root barriers, you can plant any species,” he said. 

“Poplars are a good tree for Calgary.”

During the upcoming Executive Committee meeting, Coun. Chabot said that he will call on the city to take responsibility for the way poplars have eroded sidewalks, and that he would like to see trees with less invasive roots replace them.

Yet, Friesen said that even if a different species replaced poplars, it’s likely for the new sapling to follow the same path as its predecessor. Instead, he recommended that the attention shift toward changing the sidewalk material from cement to something more adaptable. 

“It would be good if the councillors called for additional work, innovative work, to find a more sustainable sidewalk design,” said Friesen.

Preaching the same idea, Addy said that if the goal is to ensure that residents see their neighbourhoods’ walkways as safe and accessible, then she urges the city to fund implementing rubber pavement as opposed to removing trees. 

“If we keep designing and building sidewalks the same way we are now, we’re going to have this problem, so what is the city going to do differently to help the tree roots go down deeper and not stay shallow?” said Addy.