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: Oct 03 2020 15:36:49
Hi Ben
Yes I see what you mean. I’m thinking ‘KISS’ for sure. Keep it simple
stupid - Transparent, quick, practical - move on.
Some very clever people clearly applying themselves to such matters -(
which great & thanks) but, over doing it. Ecologists are good at over
thinking things too. Too clever for their own good sometimes.
Environmentally; I’m of mind that we have 10 years to assess every ward and
write up a an action plan for each & get on with it. That is if we are
serious about sustainability.
👍





On Sat, 3 Oct 2020 at 16:21, Ben Rose <benrose@xxxx.co.uk> wrote:

Hi Bryn,



The theory of maintaining tree canopy cover in planning decisions is
appealing. However the practice of enforcing it can be complex. An example
of a recent policy that is based on canopy cover is provided by High
Wycombe District Council. It is put forward as a 'simple' system but it
looks pretty awkward to me. Take a look for yourself, it is explained here:




https://www.wycombe.gov.uk/uploads/public/documents/Planning/New-local-plan/Tree-canopy-cover-assessment-report.pdf



and supported by this spreadsheet:




https://www.wycombe.gov.uk/uploads/public/documents/About-the-council/Have-your-say/Consultations/Canopy-cover-SPD/Canopy-calculator-canopy-cover-SPD-consultation-draft.xlsm



Best regards,



Ben





Sent: Friday, October 02, 2020 at 8:14 PM

From: "Brynley Andrews" <brynley.andrews@xxxxxx.com>

To: "UK Tree Care" <uktc@xxxxxx.tree-care.info>

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



Hi Jim

Thanks for that.

I see TCC as a very pragmatic tool. For example, today a site with a
mature

HC where they want to extend a house - no TPO/CA/ AONB. Good feature,
usual

issues - informing the owners & architect that the ward is already ~30%

deficient in TCC puts extra emphasis on its retention - but the owners

could remove it & worse case scenario compensate with projected TCC

plantings, with gain, on & off site - the end being real sustainability,
I

suggest.

I find it very useful.

Developers I talk about TCC & the associated compensatory measures don't

have a problem with it. LPAs use it to set targets. What's not to !Ike?

Hallelujah brother!





On Fri, 2 Oct 2020, 18:37 Jim Quaife, <jq@xxxxxxxxxxxxxxxxx.co.uk> wrote:



Don't worry about being evangelical Bryn, the more we understand about

tree cover the better.

The mainstay of UK arb consultancy relates to planning and development.

With TCC as a guide for policy, whereas the intention is helpful, many
of

us deal with individual sites where tree retention/removal is a matter
of

the site-specific circs, and policies have to be interpreted.  I have
had

experience (fortunately uncommon) of what I would describe as a
"robotic"

approach to trees on a numerical basis with no realistic or considered

implementation of good design.

With a wider perspective, if an "over-emphasis" upon trees is exerted

(some would argue that there is no, or shouldn't be any, such thing!)
there

is a risk of a negative approach and a disincentive for people to plant

trees.

As is usually the case one needs to wait and see before introducing any

prescriptive action, but I am optimistic that if the more esoteric

appreciation of trees can become better defined, added to all the other

world-wide problems the planet is facing, the respect for trees will
become

more pragmatic.

Jim





-----Original Message-----

From: uktc-request@xxxxxx.tree-care.info [mailto:

uktc-request@xxxxxx.tree-care.info] On Behalf Of Brynley Andrews

Sent: 28 September 2020 10:23

To: UK Tree Care

Subject: Re: Tree canopy cover as a sustainability metric: Planning for

the future - consultation



Hi Bill



Thanks very much for your input. It helps me get my head around

perspectives.



How I see it - The TCC on a small site - say an urban park of 1 hectare

could be measured using Google earth and/or CAD survey info every year
in

about 1 hour. This data would be a guide as to year to year
performance and

fed back into the planning system as an indicator of overall
environmental

performance. Lots of parks, lots of data - heah presto we know how our
area

is doing.



A ward area could re-do the FR canopy project to the same level of

accuracy/error every year? or 3-5 years and again be a guiding
indicator.

Developments that have 'gain' should increase TCC.



A plantation of sitka has wide gaps and until it gets to about 10 years

would mostly not register as TCC using the FR imagery info, which BTW
is up

to date within maybe 6 months.



I agree the canopy cover system does not differentiate well between a

wellingtonia and a weeping willow - but this is when site derived data
is

used and is more of an ecosystem services measurement than what I am

getting at - which is sustainability metrics.



We live in the societal age of data assimilation and analysis, but
arguably

the arb industry and urban tree management has not yet caught up. I am

confident it will. I fully expect that in 20 years drones will be able

survey tonnes of arb data and produce astounding feed back. Arbs need
to

get with it and use it to our and societies advantage. Sorry getting a
bit

evangelical/ranty here.



Thanks



Bryn











On Mon, 28 Sep 2020 at 09:44, Bill Anderson <

anderson.arb.original@xxxxxx.com>

wrote:



Perhaps your average urban-based arb understands that his day-to-day

employment is likely to mean the figures obtained for canopy cover
can

very

rapidly become inaccurate. And I suspect that counting trees is often

confused with measuring canopy cover as well. Not to mention the

conundrum

that a spreading weeping Willow might be only 10 metres tall but
have a

crown projection greater than a 30 metre tall Wellingtonia. It might
be

better, in terms of particle interception at least, to attempt to
work

out

total crown volume per hectare. I mean, a recently planted parcel of

Sitka

Spruce would bear no resemblance to a similar sized parcel
immediately

prior to harvesting, but still provide more or less the same "canopy

cover."

Wouldn't it?



On Mon, 28 Sep 2020 at 09:27, Brynley Andrews <
brynley.andrews@xxxxxx.com



wrote:



Hi Jon



Thanks for the questions. I wish I had the time to answer your

questions

thoroughly, & besides this thread is really looking for info to
backup

the

principle of using TCC as a metric of sustainability - because of
the

arboricultural implications and ease of use/transparency - so as to

raise

the issue of tree cover within the planning for the future
consultation

process.



1. The <2% I meant is the threshold set by forestry research (FR)
for

standard deviation within their UK ward tree canopy mapping
project.

As a

baseline for further consideration within the planning process. FR
give

info linked here - that indicates the UK has an average of 15.8%
TCC,

which

based on the hundreds of wards done seems like it is fairly
accurate.




https://www.forestresearch.gov.uk/research/i-tree-eco/urbancanopycover/



2. The above FR TCC process is repeatable/reproducible and

transparent/open

access, and so for the sake of a baseline scoping metric of

sustainability measurement I suggest it is good. And simply
reflects

common-sense; also, it is readily understandable by all and Google

Earth

/

site visits enables verification.



3. As you know, CAD shapes can be derived from drawn/produced
polygons

of

any shape, from multiple survey methods thereby giving good enough

accuracy

again. I did not envisage circles.



What concerns me more than the technical issues you raise, is that

there

is

seemingly a lack of engagement with urban TCC measurement by the
arbs.

I

hope I am wrong? But that is a whole other topic for another day,

perhaps.



Thanks



Brynley





On Fri, 25 Sep 2020 at 17:58, Jon Heuch <jh@xxxxxxxx.co.uk> wrote:



Brynley







i)                    You can’t measure accuracy! (that is - from

sampling).



ii)                   Please provide me with a reference that

suggests

they

are estimating something to “2%”.  If they do have a measure it
will

be

of

precision. Something very different to accuracy. If you apply
more

sample

points your precision increases & that appears to give you a good

measure.

But it doesn’t because of the problems I describe.



iii)                 CAD will very accurately measure what you
put

into

CAD.

That is not the problem. If you draw a circle around a tree, CAD
will

do

a

wonderful job of telling you the area of the circle. The first
big

problem

is that images have shadows, varying from image to image; if you
are

dealing

with only one image, there will at least be some uniformity
across

the

image. The second is that trees are not uniform cylinders,
spheres or

other

shapes so whatever you measure, however you measure.







You might want to read the musings of Francisco J. Escobedo
(used to

work

with I Tree; Google Scholar gives you an entrée to his work) who

gave a

talk

at the AA conference in 2016. He at least started to discuss
some of

the

statistical issues related to inventory of the urban forest. I
can

tell

you

simply you won’t pick up modest but real changes in canopy cover!

Undoubtedly you will generate numbers. Undoubtedly they will be

different.

Will they be meaningful? Most unlikely.







Jon













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--

Brynley M M Andrews MSc., C.Env., M.Arbor.A.

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and

Stockholm Tree Pits

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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







--

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









--

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











--

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

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--
Brynley Arboriculturist / urban forester



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The UKTC forum is supported by Bosky Trees arboricultural consultancy and
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