[CANUFNET] [EXT] Re: Optimal Tree Health Condition Rating

[Lyford, Cabot]

FYI, in Vancouver we have a database of our street trees going back to 1990.  Condition ratings are, as mentioned, very subjective and changeable, but the system we’ve used over the years is:

0              dead
1              very poor
2              very poor/poor
3              poor
4              poor/fair
5              fair
6              good
7              very good
8              very good/excellent
9              excellent

Filtering out all stumps and trees designated for removal, our average condition rating as of September 2021 was 7.048.  This may be skewed toward the high end because it includes a lot of new plantings that are usually put in as condition 9 at first, until we visit the tree again, which might not be for a few years.  Generally speaking, we consider a 7 to be equivalent to 70%, etc.  We have no 100% rating, in other words.  It’s the system we are familiar with, so it works reasonably well for us, mostly as a risk-management tool.

We’ve never set a ‘target condition rating’ for our trees.  Tree condition ratings do, on rare occasions, improve for individual trees if our pruning or other tree care efforts yield results, but usually they stay the same or go down.

Regards,
Cabot Lyford (he/him)
Arboriculture Technician
Vancouver Park Board
604 257 8587
Cabot.lyford at vancouver.ca


From: CANUFNET <canufnet-bounces at list.web.net> On Behalf Of Julian Dunster via CANUFNET
Sent: Thursday, January 6, 2022 1:44 PM
To: canufnet at list.web.net
Cc: Julian Dunster <jd at dunster.ca>
Subject: [EXT] Re: [CANUFNET] Optimal Tree Health Condition Rating

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Bonjour Bruno

I think you are looking for a suggested health rating. Using the word target may be confusing as that is usually reserved for the target of concern in the event of failure. I am not sure there is such a thing as a suggested health rating that can be equitably applied in all cases. Many of us use a very broad scheme: Good (no obvious problems of concern), Fair (some problems but none of them too serious right now, but a downward trend is likely), and Poor (obvious problems that the tree will not overcome and mortality is likely sooner not later). I try to avoid splitting it down into really fine components because they never ever work in every situation, most of it is very subjective, and it can change quite rapidly.   I really don't know what the percentage figures would tell you (I am assuming that you did not mean percentage of canopy cover). With climate change (prolonged summer drought and heat domes year after year) overall tree health in urban and rural areas is trending downwards very rapidly on the west coast, especially on Vancouver Island.

Yours sincerely,

On Behalf of Dunster and Associates Environmental Consultants Ltd.





Dr. Julian A Dunster R.P.F., R.P.P.., M.C.I.P., ISA Certified Arborist,

ASCA Registered Consulting Arborist # 378,

ISA Tree Risk Assessment Qualified

Honourary Life Member ISA + PNWISA



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On Thu/1/6/2022 9:57 AM, Bruno PAQUET via CANUFNET wrote:
Hello everyone,
Best wishes for the year ahead with hopefully less COVID considerations.
Being responsible for the urban forest of a borough on the Montreal Island, I am looking for references on the optimal target rating for the health condition of public trees.
A recent study I commissioned (2021) showed, based on a sampling of 10% of our public tree population, that the condition rating of our trees along streets and in parks was 67%.
I have consulted many documents and have not found anything specific about a target for such an optimal rating, which would be recognized by the community as desirable. A target score of 100% would obviously be completely unrealistic but what should we aim for, 80, 85 or 90%.
Your comments would be appreciated.
Thanks


Bruno Paquet

bruno.paquet at montreal.ca<mailto:bruno.paquet at montreal.ca>






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