Have you ever come outside and seen a branch laying on the ground or perhaps heard a loud crack and fall? A branch can crack and break anytime wind, snow, ice or just gravity puts more pressure on it than it can handle. Branches grow to withstand a certain amount of these forces but they also can develop weak spots, called defects, around which they can break easier than normal. Holes, clustered branches, inclusions, and cankers caused by infection are some examples of weak areas in a tree.
A branch can also break on a hot, dry day due to a moisture imbalance within the wood which causes the wood fibers to separate. This is called “summer branch drop” and it’s still not fully understood by tree experts.
Lastly, wood strength varies greatly by species. For example, White Pines are naturally more prone to breaking under high storm winds than Oaks. And certain trees are prone to developing defects such as the Bradford Pear which develops multiple branches originating from one spot on the trunk.
If you have a tree that has a break or crack and it is concerning to you, it’s best to have an arborist check it out in a Hazard Inspection.
The recent story in Abington, MA in which 2 people were killed when a tree fell on their car has brought about the question who will pay and who is responsible for these deaths? The land that the tree was on is supposedly owned by the City of Abington, but because it is unclear, the city must take a new survey of the property lines to see if the tree actually was on city land and also provide evidence that the city had exercised their duty of care to avoid a large payout. A duty of care is the city’s legal obligation to ensure a reasonable degree of safety for people and property near their trees. As a tree owner, you also have the same duty of care for trees on your property. Simply calling a tree falling over an ‘Act of God’ doesn’t always avoid a pointed finger.
Maintaining your trees at the very minimum should include an assessment of trees that could fall onto people or property (including neighbors, public sidewalks, roadways and utility lines). In the event that one of your trees did fall and a court case ensued, you would be able to prove that you exercised your tree care duty/responsibility by having an assessment done by a Certified Arborist. Sometimes, tree removal may be your only option depending on the conditions that are discovered upon inspection and your comfort level with the fall likelihood. In other instances, there are ways to lessen the risk that it will fall by installing cables/braces, specialty pruning and/or continuing to monitor the tree on a regular basis and before storms.
There will always be a risk as long as a tree is standing, but these options help to lessen the risk level and allow you to keep a tree that you really love and wouldn’t want to remove. Large, mature trees are typically what cause people to be scared but they also provide many benefits such as providing shade and cooling, clean air, etc. and are worth keeping if practical and non-threatening.