Trees in Towns 2

[David Humphries]

I'm going to have to mate, I need to get this assignment in. So the reference is;

Mr D Humphries, Senior Arboriculturist, City of London?:lol:

 

That would be 'Trees Management Officer' if you don't mind

 

I wonder how many authorities have a completed inventory and have implemented a continuing inspection regime. Looking at some of the recent failures where symptoms of decay were evident (in the press and on the internet) I'd suspect not enough.

 

We have in the region of 25,000 trees across our division in North London, all the formal areas (parks mostly) have the trees inputted on to the inventory.

 

But in total, perhaps only 20% of the trees are currently on the system.

 

 

Our annual inspections have moved from a risk zoning strategy to a risk sequencing system, where areas are prioritized according to their target and occupancy levels (eg; A roads, railways, B roads, parks etc....)

These individual sites are then walked over each year starting with priority area 1 onwards with only trees with any works deemed as required with 12 months listed for work schedule.

 

This is resource based, so we get what we can completed with the in-house inspectors that we have who have other areas of work to deal with including storm damage (lots of that this year ) tree health works including p&d inspections for Chalara, Massaria, OPM etc....also our veteran tree program, which probably means in reality, that we won't get all the areas walked over in a calendar year. But as long as the sequence is adhered to and the higher priority areas are walked over, then we are doing what we can to discharge our duty of care.

 

Currently in the process of rewriting our 'policy' which should be finished in the next few months.

 

 

 

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[Gary Prentice]

David, as i'm learning more it's becoming easier to appreciate the issues and resource constraints that arbs in LA's are battling against. It's definitely an uphill struggle.

You couldn't finish your strategy sooner could you, by about tuesday, as my next assignment is a critical appraisal of an existing current policy:lol: I'm sure yours would be interesting, given the variety of the trees under your management.

 

regards gary

[David Humphries]

I remember well the deadlines from the level 4, can't imagine (well don't want to if I'm honest, as I'm having a break ) how stressful the deadlines are on the 6.

 

Hats off

 

 

Not back in till Thursday I'm afraid

 

Good luck with it.

 

If you haven't come across it, here's the City's tree strategy (that is the square miles strategy) which was adopted in 2012

We have a number of open space divisions outside of the square mile that are in the process of putting together a joint tree policy which will in essence fit within the over arching strategy.

 

http://www.cityoflondon.gov.uk/services/environment-and-planning/planning/heritage-and-design/Documents/Tree-Strat-Part-1-Complete.pdf

 

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[daltontrees]

Our annual inspections have moved from a risk zoning strategy to a risk sequencing system, where areas are prioritized according to their target and occupancy levels (eg; A roads, railways, B roads, parks etc....)

These individual sites are then walked over each year starting with priority area 1 onwards with only trees with any works deemed as required with 12 months listed for work schedule.

 

It's interesting to see, when all is said and done about qualitative and quantitative risk assessment, how it manifests itself in practice. I am curious though on one point. Dredging up the old Matheny/Clark concept of risk = target x size x likelihood of failure, that is generally accepted, you are prioritising the inspection of high target sites and then acting on trees there with let us call it imminent need for intervention, thus dealing with 2 of the 3 M/C measures. How do you factor in size, the third factor? Is it built in to the 'deemed as required' aspect of the decision making? Or do you have a size cut-off so that smaller trees are consigned to a lower priority for inspection (if ever)?

[Paul Barton]

The size part of that equation never really made much sense to me. A 'small' dead limb that drops from 100ft has the potential to harm more than a larger branch that falls 10ft.

 

With regards to the size of trees - it make sense to me to have a minimum tree size for annual inspections...soon enough young trees with high growth potential will need to be included as they reach the minimum criteria but small ornamental trees may never need inspecting.

 

David - do you record all trees during the walkover - or just record those that need some work?

 

If you don't have an inventory of all the trees in these areas, are you happy enough that if a tree failed that wasn't recorded you could say that it definitely was inspected and that at that time there were no significant defects etc?

 

...if this discussion runs, perhaps we should move it to a new thread so as not to hijack Gary's Trees in Towns II thread which is worthy of its own discussion...

[David Humphries]

Paul, the date is logged on all plotted trees that are inspected to provide an audit trail of who and when the tree was recorded.

 

We intend to add more trees to the inventory as we times moves on.

(the majority of trees in high to medium risk areas are all ready plotted)

 

 

Again, this is resource based.

 

We have in the past brought in outside help to plot a given area where our resource is tied up. But the vast majority of our trees are plotted and then inspected in-house.

 

Trees that are not on the inventory are looked at post storm, any works required as a result of storm damage are added to our schedule of priority works.

These events are recorded.

 

We don't intend to have each and very tree on a database as a large number are secondary woodland trees.

 

We focus on our known (measured) footfall figures, so where there are honey pot areas we focus resource to these.

 

It would be a disproportionate use of resource to capture all trees within our management.

 

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[Gary Prentice]

Resource, resource, resource. It's always about the money isn't it.

 

Thanks for the information David, on the C of L strategy. I've had a quick look through it and may well use it for the assignment. I'm guessing that the city has some specific issues that may make the strategy different from others - less run of the mill so to speak, which could make a more interesting topic.

 

As a quick question, are there any veterans within the city itself? Sorry if it's a stupid question, but I didn't notice any mention in my quick perusal.

[Gary Prentice]

 

...if this discussion runs, perhaps we should move it to a new thread so as not to hijack Gary's Trees in Towns II thread which is worthy of its own discussion...

 

I'm easy on this, all good.

 

I am however starting to think about the personal project assignment and have a bit of an idea starting to formulate. I may wish to ask a few questions and get some opinions on it in a few weeks. Has anyone got access to Mark Johnsons article, which I think was in the horticultural press about the survey and the industries reaction to it?

[David Humphries]

It's interesting to see, when all is said and done about qualitative and quantitative risk assessment, how it manifests itself in practice. I am curious though on one point. Dredging up the old Matheny/Clark concept of risk = target x size x likelihood of failure, that is generally accepted, you are prioritising the inspection of high target sites and then acting on trees there with let us call it imminent need for intervention, thus dealing with 2 of the 3 M/C measures. How do you factor in size, the third factor? Is it built in to the 'deemed as required' aspect of the decision making? Or do you have a size cut-off so that smaller trees are consigned to a lower priority for inspection (if ever)?

 

We're not aspiring to eliminate risk Jules, we're managing risk.

 

If we were governed by assessments weighted toward quantitative we would be fighting an endless dynamic list of works. Our focus is more on target and likelihood.

 

The priority works list is reviewed monthly and contain works that are required over an 18 month period.

Some of these works slip lower down the list when newer works are identified with a greater risk associated.

 

 

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[David Humphries]

 

As a quick question, are there any veterans within the city itself? Sorry if it's a stupid question, but I didn't notice any mention in my quick perusal.

 

Not really

 

Imagine the great fire took with it any old trees that had escaped the constant development of the city.

 

 

 

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