[CANUFNET] Healthy tree definition

Thu Jan 28 13:02:50 EST 2010

Gerard makes several salient points, in particular that trees are not naturally high headed. There is no disagreement here that low branches aid trees in many ways. It's foolish to dispute Darwin. But trees don't naturally grow beside concrete driveways or within 1.5 metres of roadways.

It's great to propose a tree utopia, but in reality there are strongly vested interests that do not always agree with what is best for trees. In an urban setting, we as arborists must make pragmatic choices if we hope to nurture our urban forests. A low headed deciduous tree in a busy urban boulevard setting will at worst be torn apart in the first few years as it begins to grow out into streets and sidewalks. Homeowners are callously unappreciative of the optimal growth requirements of trees if they perceive those trees to be in their way; moving trucks and roadway resurfacing vehicles even less so; perhaps it is the classic case of the wrong tree in the wrong location.

Note that I referred to a blvd setting in the comment. Perhaps I need to clarify: the comment is not the standard, it is in reference to a particular site. The comment changes, the standard, which does allow for decurrent habit, does not. Furthermore, I urge you to read the standard that I cited in depth. It expands greatly from form to reference the old CTLA (Now CNLA standards). In particular 2.1.1: "All materials shall meet the horticultural standards of and comply with, all sections of the latest edition of the Canadian Landscape Trade Association (C.N.T.A.) planting specifications". I believe that these standards are national and developed in direct consultation with Nurseries. There you will also find reference to the importance of height of branching in street tree bid specifications.

Gerard, please feel free to contact me directly.

Regards,

Travis Kennedy, BSc, AIT
River Valley, Forestry and Environmental Services
12304 - 107 Street
Edmonton, Alberta
T5J 2R7
p 780 496 4954

-----Original Message-----
From: canufnet-bounces at list.web.net [mailto:canufnet-bounces at list.web.net] On Behalf Of For Trees
Sent: Wednesday, January 27, 2010 10:46 PM
To: 'Canadian Urban Forest Network'
Subject: Re: [CANUFNET] Healthy tree definition

With regard to Travis' comments, it seems to me that this wording leaves it completely open to whatever  subjective interpretation your inspectors may have on any particular day, with no recourse whatsoever for the contractors or nurseries that have their trees rejected.  You are basically saying that a tree must conform to your standards, whatever they may be, right or wrong.
In point of fact, trees are not normally high headed, and must be pruned that way in the nursery. Such pruning is clearly detrimental to the health of the tree, and in most cases, stunts the growth, reduces taper and trunk strength, and invites disease and poor compartmentalization, which can lead to trunk cracks, sunscald and several other defects that I can think of. This is all well researched and documented in Alex Shigo's book 'A New Tree Biology" 1989 and in "Modern Arboriculture." 1990. Other researchers such as Gilman have since written excellent books on the topic of pruning and pruning trees for urban areas in the nursery, which have been universally accepted by most of the rest of North America and the world.

And what of trees that do not normally have a central leader in the Edmonton area? Trees like Green Ash, Mayday, Schubert, Amur Cherry  and Ornamental Crabapples very rarely possess a "single dominant, well developed leader." I can only imagine that very few otherwise healthy trees of these varieties survive your inspection process!

Even if any particular Urban Forestry department actually knew what a "healthy tree" was and could specify this in a way that was "not open to interpretation", there is no guarantee that picking a tree simply on the basis of "good" form will guarantee future good health, especially in a place where trees are notoriously difficult to grow, such as the Western Prairies. Planting methods are the single biggest factor influencing the success of a tree. And while you are  perfectly right not to accept a tree with obvious signs of abuse such as scrapes and broken branches, we continue to plant the healthiest of trees in the worst of places and blame the tree when it dies. Trees need room to grow both above and below the ground to sustain themselves, and usually have neither in most Urban Areas in the world today.
Fixating on a tree's form, especially when the form is entirely unnatural to the species or variety,  certainly should never be considered the only attribute of potential  good health!
We obviously need to rethink the whole notion of "tree health" when Urban Areas are still in the design process.  I believe it is possible to shape cities to conform to nature, but nature cannot be retrofitted to fit our cities, if our cities are to be sustainable.
Food for thought.
[cid:183432716 at 28012010-0E84]
Gerard Fournier
Board Certified Master Arborist #PR-0130BT
Tree Canada Community Advisor-Southern Alberta

President
For Trees Company Ltd.
1-877-390-TREE (Alberta toll-free)
http://www.fortrees.ca<http://www.fortrees.ca/>

From: canufnet-bounces at list.web.net [mailto:canufnet-bounces at list.web.net] On Behalf Of Travis Kennedy
Sent: January-27-10 4:17 PM
To: 'Canadian Urban Forest Network'
Subject: Re: [CANUFNET] Healthy tree definition

Our Design and Construction standards touch briefly on "healthy" but add a number of other quality measurements to reinforce our intent:

Refer to section 02930 2.2 and 2.3  in Volume 5<http://www.edmonton.ca/city_government/documents/PermitsLicences/D_and_C_landscapsng.pdf>:  City of Edmonton Design and Construction Standards.

A design review comment that we like to make on submitted drawings from developers usually contains some or all of the wording below (this particular case is in reference to deciduous blvd. material):

"All trees to be high headed and exhibit a full and uniform crown, with a single dominant, well developed leader. Trees with broken or damaged or missing leaders will not be accepted. All plant material must conform to the City of Edmonton Design and Construction Standards."

This comment in combination with the standard helps prevent confusion about what is and isn't acceptable during our CCC / FAC inspection process.

Regards,

Travis Kennedy, BSc, AIT
River Valley, Forestry and Environmental Services
12304 - 107 Street
Edmonton, Alberta
T5J 2R7
p 780 496 4954

-----Original Message-----
From: canufnet-bounces at list.web.net [mailto:canufnet-bounces at list.web.net] On Behalf Of Kowalyk, Bohdan (MNR)
Sent: Monday, January 25, 2010 7:05 PM
To: Canadian Urban Forest Network
Subject: Re: [CANUFNET] Healthy tree definition
There are various tree classification systems depending on intent.  For some purposes, it may be appropriate to require confirmation by a qualified person, subject to an authority's approval, that a healthy tree is not likely to degrade in health and functional attributes for at least the next 15 years.

Bohdan

________________________________
From: canufnet-bounces at list.web.net [mailto:canufnet-bounces at list.web.net] On Behalf Of SVescio at thunderbay.ca
Sent: Monday, January 25, 2010 1:02 PM
To: canufnet at list.web.net
Subject: [CANUFNET] (no subject)

Hello out there,
Is there an accepted or standard definition for the term "healthy tree"?  We would like to revise the wording for acceptable condition of trees at final inspection and do not want the health of a tree open to general interpretation.  Thanks.

Shelley Vescio RPF
City of Thunder Bay
(807) 625-2473
(807) 625-3258 (fax)

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