Included bark is not a household term, but understanding how it identifies potential weaknesses in trees will help keep your property free of tree damage.
Unless you’ve spent some time in a forestry or arboriculture educational program, you’ve likely never even heard of included bark – and that is alright. Knowing what included bark is, or knowing how to define it is not important; however, identifying included bark on your trees can help prevent broken limbs and damage from falling branches.
How to Identify Included Bark?
There are two main identifiers to search for when looking for included bark. First, you can look for the sharp “V” shapes in the junction of branches. The more the tree grows, the deeper the “V” gets, and ultimately the weaker the junction gets. The second identifier can be spotted when looking at the “side profile” of a tree. Included bark will create a bulging effect, as it is essentially sandwiched between two stems as the tree grows.
Included bark forms in the junctions of co-dominant stems where there is a narrow angle union – meaning the junction looks like a “V” rather than a “U.” As the tree grows (picture the age rings of a tree) the narrow union will essentially fill with bark and create a growing area of structural weakness in the tree. Even in young trees, when you notice a very narrow angle (creating a “V” at the junction of branches) it is likely that stress put on the either of the co-dominant stems can cause splitting, or even cause the stem to break off at the junction.
As a tree ages and grows, included bark becomes more of a danger to your trees and property. In New England, storms can deliver high winds and heavy snow that puts significant stress on tree branch unions, ultimately causing them to split and break at the junction.
Preventing and Managing
Preventing and mitigating risk on trees with narrow joints (and included bark) can be accomplished through:
- Crown Reduction Pruning – Reduces the stress on the joint and limits the leverage of the wind and snow during storms
- Cabling and Bracing – Properly installing cables or through bolts can prevent wind and snow damage and secure the limbs in place
- Removal of the tree – This should be a last resort, but may be necessary in some cases
If you identify a tree that may possibly have included bark we advise you to contact a Certified Arborist to inspect the tree for safety.
Included bark can cause concern for any type of tree, but in our area it is very common in varieties such as the Bradford Pear Tree seen here. The narrow joint here gave way to the high winds of Hurricane Sandy. Evidence of included bark was noticed, and it is likely that cabling the tree would have saved it.