Trees in urban residential areas seem to be more prone to damage because of an increase in windstorms and because of maintenance work, which has weakened trees.
I currently live in the east end of Montreal in Mercier-Hochelaga-Maisonneuve. Over the past few years, I have noticed what seems to be an increased fragility and decline of trees in my neighbourhood and in other Montreal boroughs. In summer 2017 trees in the Notre-Dame-de-Grace (NDG) borough were severely damaged and/or felled, especially in Girouard Park. Since then, I have noticed similar damage to trees by windstorms in my current neighbourhood, although nothing as extensive as the impact of the 2017 storm. Trees in urban residential areas seem to be more prone to damage than they were before for two reasons: 1) an increase in windstorms and other forms of extreme weather and 2) infrastructure maintenance work, which has weakened trees so that they are more vulnerable to severe weather.
I spoke with Éric Champagne, Horticultural Supervisor in the Buildings and Grounds unit at McGill University. We discussed the many reasons that urban trees may be damaged or weakened, particularly through maintenance work, which is extremely common due to Montreal’s aging infrastructure. Champagne indicated several maintenance-related causes of tree damage: soil compaction by heavy machinery; road salt use during the winter; and sewer system repair work. All adversely affect tree root systems. Soil compaction deprives trees of water, nutrients, and oxygen; road salt seeps into water runoff and dries out a tree’s root system; and sewer construction can damage tree roots, causing exposure to fungus and disease (É. Champagne, personal communication, April 15, 2021). Some of these diseases and fungi can cause the tree core to rot, without there being obvious external signs. Unless disease is detected and the infected tree removed, it can be snapped more easily in a windstorm. (Champagne, 2021).
According to Environment Canada, the damage to the trees of Girouard Park in 2017 was caused by a microburst, a downdraft of wind “less than 4 km in horizontal dimension” that “can result in damage intensity similar to that associated with a strong tornado” (Environment and Climate Change Canada, 2017). These types of extreme weather events are occurring more and more frequently, caused in large part by climate change. Phillips writes, “Canada is warming at nearly twice the global rate [and] Weather systems are moving slower, leaving more time to make an impact” (2020). Researchers of the Quebec-based climatology research consortium, Ouranos, have indicated that thunderstorm seasons will continue to become longer and more intense over the next decades (2010). My observations support the idea that tree damage is increasing in Montreal due to a combination of factors, notably infrastructure maintenance work and increasingly severe weather events.