root zone of the tree as they may indicate a lack of stability. But the most important area for evaluation of fruiting bodies or during the pull testing is what is termed the static relevant zone.This area has been shown to be vital to tree stability with regard to roots; and is an area roughly equal to 150 percent of the tree's diameter out and around the root flare. For example, a tree with a dbh of 24 inches would have a static relevant zone of 36 inches and this is the place where mushrooms or cracking during pull testing would be of most concern.
Tree sections for evaluation The form shown on page 15 — the
Integrated Risk Assessment Guide — was developed and designed by Dwayne Neustaeter of Arboriculture Canada Training and Education, and is used by both that organiza- tion and North American Training Solutions, along with a variety of public and private tree care organizations/companies throughout the United States and Canada.The way the tree to be evaluated is divided into sections may differ in some ways from those with which some tree care professionals are familiar.A description of the section is as follows: • The scaffolds are those leaders and branches
that make up the structure of the tree's canopy. • The trunk is the continuation of the trunk
of the tree beyond its first branches. • The pedestal is the lowest portion of the tree's
trunk from the root zone extending up to its first branches. • The roots are the root zone along with the vitally important static relevant zone. Each of these sections of the tree, as can be seen on the form, should be evaluated visually, with additional inspection as needed, as well as examination during pull testing, if required.An additional part of the form takes into account the type of work that will be done on the tree, thereby accounting for the forces that different tree care operations will exert on it.Tree care professionals should feel free to integrate this form,or whatever sections of it they feel appli- cable, into their existing tree risk assessment procedures,but should be aware that additional practice and training are necessary to fully under- stand and employ it effectively.
This is a brief introduction to the concepts
of tree dynamics and risk assessment. But with the basic knowledge and principles discussed here, tree crews should have a better idea of not only what to look for,but how and why to look for it.The end result will hopefully be fewer
www.arborage.com Arbor Age / July/August 2012 17
surprises from unnoticed hazards or ignored tree dynamics, and safer, more efficient tree work for all.
Michael "House"Tain is a contract climber, splicer, educator and writer associated
with North American Training Solutionswww.northamericantrainingsolutions.com and Arbor Canada Training and Educationwww.arborcanada.com.He is currently located in Lancaster,Ky.,and can be reached via e-mail at house@houseoftain.com.
