BS5837 Group Category

[jacquemontii]

Does anyone else find it difficult to distinguish between category B and C groups?

 

I personally find the definitions in the cascade chart so similar, that any group comprising trees of generally poor individual quality (maybe self seeded trees growing in competition) but with a higher/greater collective landscape value (for example located on a boundary, screening a potential development site) could be interpreted as either B2 or C2?

[10 Bears]

I would say the key to the interpretation is whether the SULE or estimated remaining life expectancy (ERLE - not as catchy as SULE), is the >20 year mark or not.

 

The CAT C trees specifically state, "trees of low quality", and whilst this is a subjective measure, it could be used to frame your classification with a little more weighting ie if it is low quality, do you expect it to outlast 20 years? This should help you decide which classification is the most suitable in the circumstances.

[oslac]

I think this is a minefield.

 

Most trees groups will have a remaining life expectancy of 40 years and as such, other than the U cat, life expectancy is a bit meaningless.

 

Many groups could sit in B/C cat, or even A/B. I have met many a planner though who will refuse any planning application if an A cat tree is implicated and also many who see all B cat trees as sacred.

 

We can no longer look at a tree or a group and make a judgement based on anything other than the cascade chart but the cascade chart along with an awful lot of the BS is cobblers as it sets tree officers, arb consultants, planners, developers and Contractors off against one another and may the strongest win.

 

Often individual trees within a group are C cat but the group as a whole is B cat . . .

 

So to answer your question . . . derrrrr!!!

[daltontrees]

I don't find it that hard. AS 10 Bears says the 20+ expectancy is the key. It's hard to justify movign a tree between band C based on quality if the life expectancy is clear.

 

Here's te crucial bit, though. I wouldn't use SULE (Sorry Mr Bears) because it'sa not in teh BS, but the BS uses both ERLE adn more usefully ERC. Estimted Remaining Contribution doesn't mean accounting for the dog days of a tree as it struggles on as the regenerating multistemmed sprouty remains of a knackered and fallen over tree, it means 'contribution' which very clearly relates to contributing amenity that one only needs to estimate how long it will be in substantially the form and size is is at assessment. So you can ignore actual biological ife expectancy and concentrate on what it's all about, amenity. And if you think about it, this also is a measure of quality, and if a tree can be expected to be in serious decline in 10 or 15 years due to what is now just the irrecoverable beginnings of decay or environmental factors, it shouldn't be B even if it is doing quite well visually.

[benedmonds]

If you can, go to the AA Barrell BS5857 Advanced Tree Assessment for planning. They take a slightly different view to some loquacious members on here, but more in line with my thinking.

 

Basically C category trees anything not worthy of being material constraint. They divide them into 10 subcategories including - size, legal exemptions, deteriorating health/condition, excessive nuisance and good management.

[kevinjohnsonmbe]

4.5.2 The purpose of the tree categorization method, which should be applied by an arboriculturist, is to identify the quality and value (in a non-fiscal sense) of the existing tree stock, allowing informed decisions to be made concerning which trees should be removed or retained in the event of development occurring.

 

I'm afraid this is a question rather than a contribution....

 

In making the informed decision about quality and value of existing tree stock, and ultimately which trees might be retained / removed on an individual potential development site, would it be reasonable to think that somebody might be taking an overview of the regional planning proposals (including historic) and bringing that collective perspective of regional tree stock (potential losses at individual sites v possible gains in planting projects for example) to bear in the decision making cycle?

 

Is that even a realistic concept?

 

I suspect probably not but it has left me thinking, how can a justifiable case for either retention or removal of individual trees be supported without some reference to broader influences beyond the single prospective development site?

 

My town has several (<50 houses) individual development sites recently completed and proposed - all on former green field sites I suspect it's the same in many rural towns. If each is viewed in isolation, the loss of some trees on each might not seem too much of a compromise given the drive to build. But collectively, I suspect they represent quite a significant loss of semi/mature trees from a reasonably condensed area.

[10 Bears]

I wouldn't use SULE (Sorry Mr Bears) because it'sa not in teh BS, but the BS uses both ERLE adn more usefully ERC.

 

Yes, I know SULE is not in the BS - I just prefer the acronym over ERLE or ERC. In my mind though, they all fundamentally mean the same thing.

 

Its a little like saying the "world wide web" is phonetically easier to say over "WWW" - sorry, couldn't think of a better example!

 

Didn't mean to add a layer of confusion for the OP...

[daltontrees]

Yes, I know SULE is not in the BS - I just prefer the acronym over ERLE or ERC. In my mind though, they all fundamentally mean the same thing.

 

Its a little like saying the "world wide web" is phonetically easier to say over "WWW" - sorry, couldn't think of a better example!

 

Didn't mean to add a layer of confusion for the OP...

 

For sure SULE is a useful concept but it refers to both contribution (useful) and risk (safe), the former is only loosely referred to in the BS and is (in terms of targets) impossible to assess until the detailed design layout is known. As such it is potentially misleading in 5837 surveys.

 

For me it's simple. The BS is literally a Standard, and all that is needed is to apply it as it is written, rather than how others interpret it. One doesn't need to be loquacious to see that 'Estimated Remaining Contribution' means the estimated length of time that a tree will continue to contribute its current amenity.

[Sylvia]

See this BS Cascade applied universally now for local planning applications - is there any counterbalancing BS standard for assessing ecological/biodiversity/wildlife value of trees?

[kevinjohnsonmbe]

See this BS Cascade applied universally now for local planning applications - is there any counterbalancing BS standard for assessing ecological/biodiversity/wildlife value of trees?

 

Jules (Daltontrees) had a thread a while back about the bat BS and how it did (or didn't) coexist very happily with 5837.

 

http://arbtalk.co.uk/forum/trees-law/94934-indirect-recent-change-bs5837.html

 

here it is