Seeing the countless fallen urban trees and branches left behind in the aftermath of the recent ice storm that blasted across southern Ontario, many local property owners are likely wondering what, if anything, could they have done to reduce such widespread damage. Although less noticeable and newsworthy, serious damage was done to rural trees so rural landowners are asking the same questions.
In fact, Toronto’s existing tree canopy has experienced a loss of about 20 per cent, estimates Stephen Smith, a consulting forester and founder of Urban Forest Associates Inc. (UFORA).
According to Smith, native trees generally weather storms better. In his own personal observation, Smith says he saw a lot of damage to Siberian elms, which are non-native species. He says nearly all of them lost 30 to 50 per cent of their crowns and most will have to come down.
The majority of native trees, on the other hand, weathered the storm with a relatively small amount of damage. “I’ve seen barely any oaks, sugar maples, walnuts or even ash that were broken,” explains Smith. “Usually it’s the ones that had prior defects in them that broke, and not all of them broke anyway. Even sick ash I know of didn’t fall. Some deadwood fell off, but usually nothing more.”
Conifers (mostly needle-leaved or scale-leaved trees) also fared well in the storm. Young cedars, hemlocks and junipers bent over but many have sprung back up. Some white pines lost large branches, but overall many of these trees will be alright. Northern species like spruces didn’t have a big problem with the weight of the ice either.
“A storm like this always sorts out the weak and strong,” explains Smith. “The ones suited to our local climate did very well, not surprisingly.”
So why are native tree species more resilient in the face of harsh conditions than their foreign counterparts? Their genetic material has simply become more adapted to local climate over time.
This is one of many reasons organizations like Maple Leaves Forever (MLF), a charitable not- for- profit, self funded organization that advocates and financially supports the planting of native Canadian maples, also promotes the use of native species when tree planting. In some cases, the use of non-native tree seeds can result in poor-quality trees and forests that are susceptible to diseases and unusual weather related events.
MLF’s various partnerships with like-minded organizations also make them a great resource for landowners looking to increase native trees on their property and/or those interested in tree planting subsidies.
Another measure that can be taken to protect trees from future disaster is to take measures to maintain their health, such as pruning. Again, during the storm that hit this past December it was evident that well-cared for trees endured better than those that were neglected or only pruned when damage occurs.
Smith agreed, pointing to his neighbour whose huge Silver maple, which is pruned regularly, lost only one small branch. However, pruning is not a task to be taken light-heartedly. This type of work requires the skill and expertise of trained arborists.
By and large, fostering large, healthy native forests will ensure our cities and towns become more resilient in the face of potential storms. In addition to mitigating the effects of climate change, trees reduce the speed at which rain hits the ground and can redirect water from our sewer systems.
Though unfortunate, disasters like this can encourage us to re-evaluate the importance of trees in both rural and urban settings and their vital connection to humans and society, at large. In my view, we should anticipate more frequent events like this which means that we need an increasing supply of native trees. Ontario’s nursery industry should take note!
John Cary, RPF
for Maple Leaves Forever