UKTC Archive

Re: Statistical Risk vs Ecosystem Services - does this compute?

Subject: Re: Statistical Risk vs Ecosystem Services - does this compute?
From: Julian Morris
Date: Dec 04 2019 12:25:57
I am very interested in this. It's a coarse approach you are taking but the 
general argument is worth seeing through.

A couple of things that come to mind immediately is that - 
- maybe avoid the terrm 'value of risk' and use 'cost of falilures' or 
something like that?
- the overall cost of failures should not just be for deaths but should 
include injuries and damage, and not just those that arise from liability to 
others.
- you would need to estimate the number of trees in the iTree area that have 
caused harm, death or damage as a proportion of the whole country, so that 
the cost of failures and value of benefits are based on the same area
- it might not then be necessary to get a per-tree figure, you could simply 
say £value of benefits / £cost of failures = X
- the average cost of failure per tree can be expressed theoretically as £ 
cost of failures/ no.of trees. 
- X would be the amount by which the risk would need to increase before costs 
outweighed benefits. I expect it would come out at about 30.

I'd be happy to stand corrected and to hear others' views. 

Julian A. Morris - Professional Tree Services
jamtrees.co.uk  and  highhedgesscotland.com
0778 XXX XXXX - 0141 XXX XXXX


Sent: Wednesday, December 04, 2019 at 11:42 AM
From: "Corder, Chris" <Chris.Corder@xxxxxx.gov.uk>
To: "UK Tree Care" <uktc@xxxxxx.tree-care.info>
Subject: Statistical Risk vs Ecosystem Services - does this compute?

Dear all, 

I am a sad case. I only have numbers to comfort me.
So I was wondering where the risk-benefit of trees might lie.
Maybe someone has already done this?
If not, does the following compute?

For arguments sake...lets agree that the background of risk of death in 
'public spaces' in the UK seems to be in the order of 1/10,000,000
Lets also assume/agree that the Value of Statistical Life is £2M
6 deaths per year = value of risk of £12M per year
“A value of statistical life of £1,000,000 is just another way of saying 
that a reduction in risk of death of 1/100,000 per year has a value of £10 
per year” (HSE, 1996)"
Therefore, divide £12M by 1/10,000,000 = risk value of £1.20
The i-Tree Eco London study found that 8,421,000 trees provided 
£132,700,000 per year of ecosystem services i.e. £15 per tree per year (or 
near as damn it). So lets assume £15 per tree might be about right.
£15 eco value per tree/£1.20 risk value = 12.5
So...is it right to say that the background risk from trees would need to 
be 12.5 times greater before the ecosystem benefits start to become 
outweighed?
If so, then presumably the background risk from trees could increase to 
somewhere in the region of 1/800,000 before the risk starts to outweigh 
ecosystem benefits?
(Which is sort of where the Tolerable/Broadly Acceptable region of the ToR 
Framework lies...is this coincidence?) 

Does this compute or have I gone start raving mad?

p.s. I get the daily digest...so I won't see any replies in real time. So 
thanks in advance. And sorry in advance for delay in reply. 

All the best, 
Chris 

Christopher Corder PDArb (RFS), BSc (Hons) in arboriculture, MArborA
Assistant Arboricultural Manager
Hampshire Highways 
Tel: 0300 XXX XXXX
Web: www.hants.gov.uk/roads
@Hantshighways

© Hampshire County Council 2017 | Disclaimer | Privacy Statement

-----Original Message-----
From: uktc-request@xxxxxx.tree-care.info 
<uktc-request@xxxxxx.tree-care.info> On Behalf Of Alastair Durkin
Sent: 03 December 2019 08:56
To: UK Tree Care <uktc@xxxxxx.tree-care.info>
Subject: RE: Replacement trees in an area TPO

Hi Jon the situation is this:

If you have an area TPO and allow a tree to be removed, subject to 
replacement planting then you MUST either make a new TPO on the replacement 
OR formally 'vary' the TPO to include the new individual tree. Otherwise 
the tree is not protected. 

The 'C' business is for giving effect to planning conditions under s197, 
it's not for TPO app conditions. See section 4 of the model order. 

Hope this helps.

Alastair


-----Original Message-----
From: uktc-request@xxxxxx.tree-care.info 
<uktc-request@xxxxxx.tree-care.info> On Behalf Of Jon Heuch
Sent: 01 December 2019 14:14
To: UK Tree Care <uktc@xxxxxx.tree-care.info>
Subject: Replacement trees in an area TPO

Good folk of uktc

 

Remind me what should happen if the removal of a protected tree covered by 
an area order is allowed, but a condition is given to plant a replacement 
tree? The order may or may not contain separate individual protected trees.

 

The order can't be altered to include an individual tree shown within the 
protected area, can it?

 

The tree officer who gave permission will remember but what is there on 
record to show a protected replacement tree? The replacement tree will 
clearly be younger than the order, so not seemingly protected to subsequent 
tree officers.

 

Do area orders get conditional replacement trees? Do they get Tree 
Replacement Notices?

 

Is this just a failing of the Area order?

 

Jon

 

 




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The UKTC is supported by Bosky Trees arboricultural consultancy
http://www.boskytrees.co.uk/