UKTC Archive

Re: Tree canopy cover as a sustainability metric: Planning for the future - consultation

Subject: Re: Tree canopy cover as a sustainability metric: Planning for the future - consultation
From: Brynley Andrews
Date: Sep 25 2020 13:34:58
Hi Jon
Thanks for the input. I find that using CAD is accurate and objective, also
the FR UK canopy cover mapping method enables accuracy of less than 2%; its
repeatable/reproducible. So, I suggest methodology is not a major issue.
All the best
bryn

On Fri, 25 Sep 2020 at 10:56, Jon Heuch <jh@xxxxxxxx.co.uk> wrote:

Brynley



The concept is fine; however, there is a practical difficulty with doing
this with any degree of usefulness and truthfulness. Experience of forest
inventory & statistics is needed to understand the difficulty.



Simply, the confidence intervals of any estimate made of canopy cover are
likely to be greater than the change in canopy cover experienced over any
realistic period of time - 5 years, 10 years or possibly longer (depending
on how many trees are planted and lost). Thus you won't be able to pick up
the changes.



Furthermore, the method used for estimating canopy cover plays a
significant
role in determining the value of your estimate of canopy cover. I have just
been trying to find the comparison made in London where figures between
less
than 20% and above 25% were made...so if you were to use the identical
method between two comparisons  you could reduce but probably not eliminate
the effect (differences in shading, seasonal & daily effects, make this
difficult).



I'm sure these difficulties won't stop people making policies and even
attempting the measurements & reporting. The impacts of doing so in terms
of
raising awareness & improving funding may even come about. But, it can be
assured to be technical nonsense unless someone addresses the problem!



Jon






--
The UK Tree Care mailing list
To unsubscribe send mailto:uktc-unsubscribe@xxxxxx.tree-care.info

The UKTC forum is supported by Bosky Trees arboricultural consultancy and
Stockholm Tree Pits
https://www.stockholmtreepits.co.uk



-- 
Brynley M M Andrews MSc., C.Env., M.Arbor.A.
www.brynleyandrewsassociates.com
01935 XXXXXX
07970 XXXXXX



-- 
The UK Tree Care mailing list
To unsubscribe send mailto:uktc-unsubscribe@xxxxxx.tree-care.info

The UKTC forum is supported by Bosky Trees arboricultural consultancy and
Stockholm Tree Pits
https://www.stockholmtreepits.co.uk