Natural Notes: Tree Support and Lightning Protection Systems

This post consists of my notes from a lecture on tree protection as part of my training to become a certified arborist by the International Society of Arborculture.  The speaker was Luke Engel, a natural resources specialist with the Forest Preserves of Cook County and his lecture took place on February 18, 2015 at the Salt Creek Resource Management facility in Willow Springs, Illinois.  

Tree support systems include cabling, bracing, and guying.  Support systems are used to reduce the risk of tree failure or to extend the life of a tree.  Cables can be installed to limit limb movement for limbs that are weakly connected (e.g. codominant stems with a lot of included bark).  Cables should be installed 2/3 distance from the crotch to the branch tips for effective support.  

 A dynamic cable system is less rigid and allows for more sway in the wind.  Cabling hardware includes 7 strand grade galvanized cables, which are easy and malleable to work with.  Extra high strength (EHS) cables are stronger although less malleable.  

 Tree Cabling
Installation techniques include the use of bolts and rods (see figure 1A)  Bolts and rods should have pilot holes that are drilled 1/16'' to 1/8'' LARGER than the hardware being installed.   For screws, the pilot holes should be 1/16'' to 1/8'' SMALLER than the hardware being installed (figure 1B).  
Figure 1:  (A) Bolts going through and (B) screws
Tree bracing is a method where a straight metal rod is inserted through the crotch of the tree (see figure 2).  
Figure 2:  Tree bracing
Tree guying is used to support trees (figure 3).  Tree guying is considered permanent as the tree will not develop a good root system or wood strength.  
Figure 3:  Tree guying
Lightning Protection
Lightning Protection Systems transfers energy from lightning from the top of the tree to the ground for dispersal.  Lightning protection is mainly used on trees with historical importance.  The typical lightning protection system, diagrammed in figure 4, consists of copper conductors that are buried 10 feet deep!  

Figure 4:  Lightning protection.  Cables are buried 10 feet underneath the ground.  

Comments

  1. September 14, 2017 at 4:12 AM

    A very impressive content based on Lightning Protection which meets all today's requirements. Now the trend has come to move toward Lightning Protection system .

    ReplyDelete

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