UKTC Archive

Re: Helliwell system

Subject: Re: Helliwell system
From: Adam Hollis
Date: Jun 03 2006 07:42:42

On 1 Jun 2006, at 22:26, wrote:

Date: Thu, 01 Jun 2006 07:43:11 -0400
Subject: Helliwell system

Has anyone used the Helliwell system for assessing a line of trees individualy and arriving at a percentage figure, for those trees lost out of this line? I know Helliwell is a variable feast, but is this use of it pushing it too far
as an assessment of amenity lost


Dear Ashley

Have you tried using the CTLA's Trunk Replacement Formula method instead?

I think this method would offer you greater refinements for such an exercise than a rounding down of a collective Helliwell assessment.

However, I would recommend attending one of Scott's seminars first, as it can be a little daunting.

Without knowing the site, I'm not sure a straight numerical rounding would be appropriate, since the loss of 10 trees from a belt of 100 trees could have a greater or lesser impact than 10%:

the impact could be more or less absorbed or it could be devastating;

it could amount to no more than a timely thinning, but it might expose the object of screening or funnel the wind being sheltered.

The loss may depend on the function of the resource and its perceived value to the end user.

For more details on CTLA, please see:

We are hoping to make progress with a UK field guide this summer.




We are seeking a qualified and enthusiastic individual to undertake tree
risk assessment and management duties in the north of England. Sites are
diverse with many mature and veteran trees.
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