Western Red Cedar – Hazard Tree Analysis

Many PNW conifers have been evaluated recently for hazard tree conditions.  This may be due in part to concerns of storm events on trees and homes but also to a heightened awarness of tree health by clients.  In either case, bravo!  Awareness leads to greater understanding of the risks and ultimately lower risk when a baseline assessment is made and followed.  The analysis I take typically begins with a visual assessment.  If my client prefers a complete assessment, I then follow up with the ISA format for Tree Hazard Assessment that categorizes each element in the equation and assigns a risk value.  There is a subjective quality to this form of assessment that cannot be overlooked particularly when elements are considered in isolation, but the method is systematic.  The International Society for Arboriculture (ISA) claims that systematic approaches are the best, so I continue to use their approach.  Though I also am on the lookout for an assessment methodology that will give an accurate probability of tree failure and have not found one yet, however there is a methodology used by Austrialians that is getting close.   Enough on that!

This particular trunk crown of a mature western red cedar had a pocket of up to 6″ of basal rot at the ground line; this I found while probing on the tension side of the tree (windward to prevailing storm winds).  I located what appeared to be the cause of the rot (former construction of a nearby concrete sidewalk and likely root severing).  On balance, I noted that the tree had formed good callus around the rot in addition I observed robust branch and foliage growth and plenty of new stem growth in the tree crown.  I judged that now was not the time to perform any destructive wood investigations.

This tree represents a low risk to the homeowner for several reasons, including a lack of failure trajectory, a healthy crown, a mature age, and a healthy neighboring urban forest composed of species variety, structural complexity, lack of disease symptoms.   I was very pleased to see such a fine and dense forest in this location of Kirkland.


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