The Urban Canopy and Ice Storm Preparedness

This is being written in response to the Dec. 2nd ice storm that hit the GTHA. Many observations are drawn from this storm but some observations are drawn from previous ice storms as well.

The hope is that you can use this information to evaluate and prepare in the event that we have another ice storm.

Trees have an incredible resiliency writ within their DNA

While the remainder of this reflection will be on tree/branch failure it is worth noting that most trees survived the storm unscathed.  Day in and day out, for generations and generations, through wind, hail, and ice, trees have found a way to keep their arms stretched out and strong.  In the case of this last ice storm, they found a way to do so despite having to carry an extra bucket of water at their branch tips.  

Size and age are not the sole determinants of failure

I was amazed by some of the old trees that didn’t experience failure.  Likewise, I was also amazed by some of the young trees that did experience failure.  Therefore, just because a tree is large and appears to be old, this does not mean it will experience failure.  

Past-failure(s) are warning signs of potential future failures

Trees that have never had branch failure, were less likely to experience failure than trees that already exhibited past branch failures.  If your tree experienced failure during this last storm, your tree should be re-assessed for risk. You can also take a look at 6 ways to protect yourself from tree/branch failure.

Lower branches in a canopy are a great safety net

Branches rarely break like a dried spaghetti noodle. Rather they usually shear/tear off from a tree (see pic below). If there is no lower branch then the branch will fall until it hits whatever else is underneath it. If on the other hand, there is a branch underneath the branch that is tearing then the branch will get stuck up in the tree.  Therefore, elevating all the bottom branches of a tree may not always be the safest option for protecting people and buildings that are under the canopy.

Ice storm tree

Certain trees are more susceptible to storm damage

Silver maples, Siberian elms, and Manitoba maples experienced the brunt of the storm damage.  In general, the faster the tree grows, the less likely it is adapted for extreme weather.  Remember, damage can affect you when making insurance claims, so it may be a good idea to have a read through our article about insurance and trees.

Silver maples experienced the largest brunt of the storm damage. 

The previous point highlights one of the main reasons why this is. Another reason relates to the winter bud on a silver maple which is quite large and forms a cluster (see pic below). Since the winter bud is larger, it has a larger surface area and therefore can enable more water/ice build up. The more ice on the tip of a branch, the more likely it will fall.

Whole tree failure is rare

While I saw lots of storm damage, only 2 situations did it involve the tree failing entirely.   In the first example, the tree was very rotten in the trunk, that extra little bit of weight was enough for the tree to buckle at the knees.  The second example is of a Manitoba maple with an extreme lean (approximately 45 degree angle).  The vast majority of storm damage is from branches breaking.  

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