City susceptible to tree-cover loss

SaultThisWeek.com
Oct. 2, 2017
SARA Mccleary

An expert on the loss of urban forests Canada encourages all Sault Ste. Marie residents, and city council, to protect trees year-round from potential threats.

“Honestly it’s really hard to grow a tree inside the city, it’s hard to grow a tree in the city in the Sault,” Mike Rosen, president of Tree Canada, told Sault This Week.

“You talk about cold temperatures, a lot of road salt, not a lot of species to choose from; the growth rates are not huge compared to other cities in Canada.

“It’s very important to protect the trees in the Sault because each one is very important,” he said.

“It’s difficult to give percentages, but the last 20 years has seen “a noticeable decline in forest cover in cities across Canada,” Rosen said.

“It catches people by surprise because people are convinced that they love trees and they want to save trees and all that kind of stuff.

“People just didn’t expect that we’re actually down in forest cover,” said Rosen.

He listed the “major pieces” affecting urban forest cover: invasive insects, climate change and “the trend toward what we call densification.

“That’s the growth of cities that occurs inside the cities, not the creation of new suburbia. If not done correctly, that’s being done at the cost of trees.”

Exactly which threat is more responsible for tree loss in an area varies greatly from city to city.

Invasive species are particularly relevant to the Sault’s tree population, with the introduction locally of the emerald ash borer.

“They’ll kill all the ash trees if you don’t protect them,” said Rosen.

“In Ottawa, roughly 20 per cent of the forest cover has been lost in the last five years to emerald ash borer, and I think it’s even greater in Montreal.

“That’s because ash was the tree of choice in the 1980s to plant because it was considered resistant to everything, which it was, until this bug came in from China.”

The emerald ash borer was first brought to Detroit, where it crossed into Canada at Windsor, then spread across the country mainly by people, said Rosen.

“It’s a really poor flyer, but it’s been helped by people who inadvertently spread it.”

He specified the movement of firewood. “Firewood is a major vector for a lot of bad diseases and insects with regards to trees,” Rosen said.

Insects are only part of the puzzle.

In Calgary, a prairie city already with minimal tree cover, “It is the climate,” said Rosen, noting the city’s experiences with floods and the September snowstorm three years ago that killed a large number of trees.

“Another one is Prince George, B.C.,” said Rosen.

“It’s a very northern city that has seen a lot of pine trees killed off by mountain pine beetle.

“Mountain pine beetle is a native insect actually of Canada, but in the absence of very cold temperatures, its population grows out of control, which is exactly what’s happening.”

Meanwhile, bigger cities like Toronto and Vancouver experience a loss of tree cover due to densification efforts.

“Because of the housing crisis and the cost of land, the amount of building that’s going on in the city limits of Vancouver is huge, and it’s being done at the expense of trees, so that’s taking its toll as well,” said Rosen.

He encourages Saultites to do their part to protect the city’s trees.

“Eighty per cent of Canadians live in cities now. In all cases, the trees are giving us incredible benefits — environmental, economic, and even psychological and physical well-being benefits,” he said.

“On the environmental side, it’s all about protection from winter winds, protection from hot summer sun shine, retaining soil, reducing sedimentation, producing oxygen, sequestering carbon dioxide and other gases.

“On the economic side, it’s about saving heating bills, saving air conditioning bills, boosting real estate values.

And also on the economic side, related to real estate values, is the increase in taxable rate, so for communities and municipalities, it’s very important to have trees because it can result in more money coming into the coffers of the municipality,” he said.

Rosen also points out that numerous studies have documented the physical and psychological benefits to living in treed areas.

Studies, mostly in United States, link the cover in treed areas to statistically lower rates of attention deficit disorder, graffiti and domestic violence.

This is “versus untreed areas where everything else is the same,” he said.

With so many benefits to urban tree cover, Rosen advocates for protecting remaining trees and replacing those lost as soon as possible.

“General protection has to do with making sure that trees are well-mulched in the summer, watering in times of drought, and pruning can make a difference in terms of assisting a tree resist strong winds, ice storms,” he said.

It’s also possible to have a more focused effort, protecting specific trees, particularly in terms of preventing the emerald ash borer from destroying all of the city’s ash trees.

One solution offered by Rosen is to inject a product called Treeazin (which was developed locally at the Great Lakes Forestry Centre) into the ash tree’s root collar, though he noted the treatment is “costly”, at about $200 per tree for two years’ worth of treatment.

“The Sault is in a good position to protect its trees because I don’t think the infestation is out of control,” said Rosen.

“When the infestation gets into really high numbers, it becomes increasingly more difficult to control, to protect the trees.”

Established in 1992, Tree Canada is the leading urban forestry charity in Canada, with a mandate focused on educating people about the benefits of planting and maintaining urban forests.

Its funding comes totally from the private sector, with some large companies providing support, including Home Hardware, Ikea, Telus, CN, and TD Bank, as well as donations from individuals and occasional government grants.