As the Greater Toronto Area and southern Ontario continue to deal with heat warnings, experts say the recent stretch of hot and dry weather is having impacts on trees and nature.
Erik Benneter, a certified arborist with Davey Tree Care Services in Toronto, told CityNews the company has seen a jump in calls.
“People concerned about the overall health of their trees, noticing some dieback in the canopy, the trees not looking as healthy as they have been looking previously (and) concerns about drought stress,” he said.
While travelling across the region, CityNews saw several trees where the leaves were prematurely changing colour. Some people reported dealing with falling leaves. Even a large tree outside the company’s north-end office isn’t immune to recent weather effects.
“Certain leaves are starting to curl and crisp up. You might notice some dieback along certain branches in the canopy,” Benneter said while surveying the tree during our interview.
He said there are some signs of heat stress affecting the tree canopy, and it’s something that can have broader implications in the future.
“Heat stress is a long-term impact on the tree. It weakens the overall health of the tree, [making] trees and shrubs more susceptible to other insects and diseases. So the impact generally is shown a couple of months or even a couple of growing seasons down the line,” Benneter said.
“Next year, next spring, the tree might not put on as much growth. That growth might be a little bit slower.
“Even this year, you might see some premature leaf drop, some browning of the leaves, you might notice the trees not looking as healthy as as it had been previously, and then that combine, over a couple of growing seasons would definitely negatively impact the tree and could potentially kill it if the tree is already under stress from other other factors.”
Trevor Jones, a federal government research scientist with the Canadian Forest Service, told CityNews he has seen it in his work, noting there can be “greater mortality rates in the trees.”
“Heat stress … is something that has happened for years and years, but I think it’s getting worse and it’s definitely sort of the duration of the heat and the magnitude of it and the impacts are getting worse over time,” he said.
“If we don’t do something, then it’s going to cause problems for our forests and have some pretty big negative impacts.”
Jones noted that heat stress can cause trees to “abort seed crops,” which can affect wildlife.
“[It] has sort of pretty big impacts on sort of species that eat the seeds, squirrels, bears, lots of birds and things like that,” he said.
It all comes at a time when forests across Canada have seen intense wildfires in recent years, contributing to the growing problem of tree loss.
Dry weather in southern Ontario: Rainfall well below average
When it comes to rainfall in Canada, there has been a lack of it in many regions across the country and southern Ontario is no exception.
Crawford Luke, a meteorologist with Environment and Climate Change Canada, told CityNews the average rainfall for the region in June and July is around 150 millimetres.
“We’re at about basically 70 millimetres of rain, give or take. There’s a lot of variation with this, depending on where thunderstorms have tracked and such,” he said.
“A lot of southern Ontario is running a bit drier than normal, but particularly east of Toronto as you get to Oshawa, Peterborough, Belleville, these sorts of areas.”
While looking at precipitation totals for various municipalities, he noted the weather station at CFB Trenton only recorded around 50 millimetres of rain for the same period.
But not all parts of Canada have been affected by dry weather as Luke said areas in southern Alberta like Calgary and Banff, and parts of northern Ontario like Timmins, have seen wetter-than-normal conditions due to low-pressure systems.
Despite the drier conditions, Luke said temperatures in the Greater Toronto Area have been only slightly above the summer average.
Meanwhile, he said there aren’t signs of meaningful rainfall relief in the short term.
Overall, it looks like we could be on the drier side through August. We’ll have to wait and see how that plays out, but definitely doesn’t look like there’s any super wet pattern on the horizon,” Luke said.
What can be done to help counteract the effects of heat stress?
The experts emphasized the importance of protecting our trees and enhancing our green spaces, noting the numerous environmental and shade benefits.
Benneter said if you have trees on your property, make sure there is a deep watering of each tree once or twice a week if possible.
He also suggested adding a slow-release fertilizer around the tree to help promote tree health. Lastly, he recommended mulching the base and root zone of each tree to keep moisture and better regulate soil temperature.
Jones echoed the advice about watering and suggested staying on top of pruning. While he is in the midst of a research project looking at how trees can be better suited to weather that is hotter and drier, he suggested potentially planting trees from farther south and ones that are better adapted to our changing climate.
When it comes to wildlife and insects, animal welfare and environmental organizations said there are improvements people can make on their properties to help cope with the heat.
Signs of heat exhaustion in birds, for example, can include panting, puffy feathers and lethargic behaviour, so offering a source of hydration is a key way to help.
Experts suggested keeping a shallower bird bath on a gentle slope in the shade and continually topping it up with water. They recommended adding a few stones to create a surface for pollinators such as bees. It was also advised to change the water every couple of days so insects don’t breed and to give the bird bath a brief cleaning two or three times a week. They also suggested placing a few shallow dishes close to the ground to help as well.
Other suggestions included planting more shrubs and creating shady spaces to allow for rest. Also, experts reiterated their ongoing call to add pollinator plants and ones rich in nectar to support bees and butterflies.
