Trunk formula technique appraisal

Trunk Formula Technique Tree Appraisal: 10th Edition Update

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Why attend?


Event date: Monday, April 29, 2019

Richmond Green Sports Centre

Room: Lounge
1300 Elgin Mills Rd East,
Richmond Hill, ON, L4S 1M5

Registration closes: Friday April 19, 2019 at 11:59 pm


The course provides information on key changes from the 9th to the 10th edition guide for plant appraisal:
– new depreciation ratings
– adjustments to tree measurement
– adjustments to unit cost calculation
– new condition rating calculations
– adjustments to rounding the final calculation

Focusing on the CTLA Trunk Formula Technique (TFT), this workshop gives an overview of the appraisal process and provides an opportunity to practice in the field. The first portion of the course is a lecture that discusses the primary components of TFT and a short history of the changes made from the 9th Edition to the 10th Edition of the Guide for Plant Appraisal. The second half of the course is a field application of the concepts discussed in the lecture. Participants will divide into groups and appraise several trees. The class will reconvene and discuss the results.

Collaborate with your peers during the field portion and practice assigning and justifying values for the Trunk Formula Technique.

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8:00 Registration (Coffee included)

8:30 Workshop Begins

LUNCH (Lunch included)

4:30 Workshop Ends

About the Speaker

James Komen

James Komen is a consulting arborist and BCMA in the greater Los Angeles area specializing in tree appraisals. He employs principles of finance and accounting to help clients make informed management decisions for individual trees and for tree inventories.


ISAO member price: $140
Non-member price: $185
Student price: $120


Certified Arborist: 7
BCMA – Practice: 3.5
BCMA – Management: 3.5
Municipal Specialist: 3


Proper personal protective equipment (PPE) must be brought to class (high visibility jacket or vest, safety glasses, and hard hat).

Why attend?

One member asked: What’s the point of this workshop, seeing as the ISA had to recall the first publication of the 10th edition and there has not yet been a second publication?

Here’s the answer from ISAO board member Pete Shields:

Thank you for your feedback. I understand the frustrations of many. I attended the 10th Edition workshop in Ohio last year that was very productive. That course explained much of what happened and also allowed the attendees to practise with the new methods. I think once many have had a chance to understand and practise, there will be a better realization for the new methods. Many of the techniques are similar with some changes to the assessment criteria. There were many notable consultants from abroad in attendance who really had a great chance to ask questions and understand, this is part of the battle.

Yes, we are all waiting for the second edition to print, eagerly. The bulk of the corrigendum were typos and references. This session in particular is not to explain the entire document, but to address some changes, especially with the trunk formula.

James Komen was at the workshop in Ohio too and has a very good understanding of the 10th, I understand he had quite a bit of input into this document as well. This is the intent of the course; the explanation of some of those changes and perhaps for some discussion.

I remember the drafts and many of the concerns, it should be noted and understood there are always different ways to appraise trees, so long as it is defensible. We are always able to use whatever methodology we feel is the most appropriate of course. The 10th is endorsed by the CTLA, ASCA, ISA among others…

The RPAC needs to thought upon. You are right in that it would be beneficial for the second edition of the 10th be out and allowed for some practise. One goal of the RPAC is to start discussions and understanding. Of course, species ratings are now obsolete in the new methodology, but the focus would likely be in establishing perhaps a list of wholesale costs for largest commonly available trees (that is part of that scope, what is common and what is available!) The installation costs are now additional and separate in the new method and should not be part of the valuation, and only incorporated after that valuation.

There are some good parts and likely some that are, for a lack of a better word as you described, controversial. My hopes with the RPAC is to discuss what those needs are and to develop perhaps some guidance for our local practicing consultants. To your point of accepting the 10th or not, that is the choice of all arborists and appraisers.

Thanks for the feedback in any event, always appreciated.