A Curtis Park resident recently filed a tree appeal involving a large tree on a neighbor’s property that is healthy but has structural problems. The city’s Urban Forestry section had granted a tree removal permit based on cracks in the main stem about 45 feet up the trunk.
Can a tree with a serious structural defect be preserved? An aerial inspection is required to accurately assess the presence of decay, the depth and the extent of the crack. If this portion of the main stem hasn’t been seriously compromised, then a support system is required to preserve the tree and reduce the risk of limb failure.
Support systems for trees such as cabling, bracing, and guying have been in use for more than 50 years.
Cables restrict the distance branches can move and, when installed across two branches with a weak attachment, will greatly reduce the risk of failure. Bracing involves the use of brace rods to fasten together a branch with a split or where two branches have split apart.
When bracing a tree, at least one cable is installed for added support. Guying is the installation of a cable between a tree and external anchor to provide supplemental support.
Unfortunately, most arborists have little or no experience with support systems and recommend removal. Why? Support systems require advanced knowledge in decay detection and analysis. The arborist also needs to ensure that the support system will accomplish its objective of providing additional support without increasing the risk of tree and/or branch failure.
The installation of a support system does require periodic inspections by a qualified arborist. Trees are living organisms and not all potential hazards can be mitigated by the installation of a support system. There are risks associated with trees and no arborist can guarantee the structural integrity of any tree because they are exposed to environmental stresses beyond our control. However, the environmental benefits of trees far out weigh the risks associated with them.
If a resident has a large tree and is concerned about limb failure or its structure, I recommend seeking out an arborist who is qualified in the installation of support systems.