[CANUFNET] spiral pruning

Mon May 11 12:21:41 EDT 2015

Hello Emily,

Just to add to Julian's comments if you want some further documentation the following link has some Best Management Practices for edge treatments starting about page 7-28.

https://www.for.gov.bc.ca/ftp/hbt/external/!publish/web/ems2/BCTS-Coastal-Windthrow-Manual.pdf

Cheers,
Ken

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Ken Byrne, PhD, RPF
Researcher / Chercheur
Forest Operations Division / Division des opérations forestières
2665 East Mall, Vancouver, BC  V6T 1Z4

* 604-222-5709
* Ken.Byrne at fpinnovations.ca<mailto:Ken.Byrne at fpinnovations.ca>
www.fpinnovations.ca<http://www.fpinnovations.ca/>

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From: CANUFNET [mailto:canufnet-bounces at list.web.net] On Behalf Of Julian Dunster
Sent: May-11-15 9:12 AM
To: canufnet at list.web.net
Subject: Re: [CANUFNET] spiral pruning

In the Lower Mainland of BC a few of us initiated spiral pruning as a technique to reduce the likelihood of windthrow, in the early 90's. Initially it was mainly Douglas-firs, hemlocks, and redcedars along new edges as development occurred. Later it was tried on isolated trees.

As an edge treatment for newly exposed trees in a forest it works well. It opens up the edge to be more 'porous' and the wind dissipates back into the forest stand without triggering windthrow.  As a treatment for individual trees trees it is less successful, and on Douglas-fir, very harmful. When we started it over two decades back, we had heard a little about branch clashing, wind sail etc and it seemed a logical approach. It turns out that, at least in Douglas-fir, the branches need to clash. When they were removed  as part of spiral pruning they moved a lot more in strong winds and increased branch failure resulted, which in turn allowed other branches to move more and encouraged additional branch failure. I recall seeing isolated Douglas-firs that had been spiral pruned, looking very motheaten years later, with massive amounts of limbs broken off. The trees not touched seemed just fine and few had fallen down.

These days I would not prescribe spiral pruning for an individual tree that is isolated. I would still recommend it as part of edge treatment for newly exposed trees (any species) in forest conditions. It should not be prohibited in all circumstances. Like many treatments there is a time and place where it can be very effective as means of meeting defined management goals.

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

BC Wildlife Danger Tree Assessor

Honourary Life Member ISA + PNWISA

www.dunster.ca<http://www.dunster.ca>

Distributor for Air Spade. www.air-spade.com<http://www.air-spade.com>

North American Distributor for Rinntech equipment. www.rinntech.com<http://www.rinntech.com>
On 11/05/2015 8:47 AM, Hamilton, Emily wrote:
Good morning,

We are looking into justification for or against spiral pruning here at the City of Surrey and I was wondering if anyone had any experience or documentation that they'd like to share related to this. Any thoughts?

Thank you,
Emily

Regards,
Emily
Emily Hamilton | Environmental Technician - Arboriculture

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CITY OF SURREY
Trees and Landscape Section, Building Division - Planning and Development
13450 104th Ave, Surrey, BC, Canada V3T 1V8
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