The focus of tree care is to enhance tree health and structural integrity over time. Trees often become damaged, are poorly managed, or develop weak structure and asymmetries. As a tree ages it declines in health and structural stability. Arborists attempt to compensate for structural changes and mitigate associated risk of failure by providing supplemental support to a tree. When used wisely, tree support systems may extend the life of a tree or reduce the risk of mechanical failure. Certain pruning methods such as reduction or thinning are often used in conjunction with supplemental tree support to further improve the structural integrity of a tree. Supplemental tree
support systems include cabling, bracing, guying, and propping. Most often, two or more of these systems will be used in conjunction with one another.

Objectives of Installing Supplemental Tree Support

  •  Provide additional strength to areas of weakness
  •  Limit branch or tree movement
  •  Reduce risk of failure potential
  •  Prevent weak unions from failing
  •  Redistribute mechanical stress of limbs
  •  Prolong the life of historic or specimen trees

Limitations of Supplemental Tree Support Systems

  •  NOT a permanent remedy for structural weaknesses
  •  NOT a guarantee against tree or tree part failure

Considerations of Supplemental Tree Support Systems

  •  Installation of support systems wound the tree under most circumstances. Drilling through tree branches and trunks is required to attach anchoring hardware to the tree.
  •  Support systems need to be monitored annually and adjusted as the tree grows.

Types of Supplemental Support

  •  Cabling – attachment of wire or synthetic fibers to branches or trunks; used primarily to limit movement and provide support.
  •  Bracing – placement of threaded rods or lag screws through trunks or multi-stemmed trees to secure weak or split attachments.
  •  Guying – connection of a tree’s trunk to the ground or neighboring tree as an anchor to prevent movement or keep a tree upright.
  •  Propping – placing solid materials beneath heavy limbs or trunks to keep them from failing.

Qualifications for Installing Supplemental Tree Support Systems

Successful application of supplemental support systems to trees largely depends on the experience of the arborist and the specific situation. The arborist must understand tree biomechanics and decay dynamics present in a tree, especially in the root system. The strain limits of installed hardware must also be identified and applied. Lastly, the installation of tree support systems in a tree represents an ongoing responsibility to the arborist. An ISA Certified Arborist is extensively trained in the technical elements of selecting, sourcing and planting trees and shrubs and held to a continuing education requirement. All planting work performed by an arborist shall be completed in compliance with the ANSI A300 technical standard and the Z133.1 safety standard.