Bs rating, I'm confused now...

[Thehardwaremonkey]

I don't know if I'm being treated as an idiot or not -help!

 

I have a single eucalyptus cider gum tree in my garden, it's stem is 510 in radius at 1.5m height, approx 12m tall and in a healthy state. Which makes an RP radius of about 6 metres(?).

The tree is on my land and close to a neighbouring development, so has been given a bs5837 rating of C3 by them/their report for the following reasons, is this correct, does lack of biodiversity make it a C3 tree always as a Eucalyptus?

 

Their response to me when I queried the category...;

With regards to the categorisation of the tree, this decision was made

following an appraisal of the tree, the species and its location.

Eucalyptus offer no foraging value to our native invertebrates and are of

little value to local biodiversity therefore the tree does not have the

'material or other cultural value' that would require it to be categorised

as a 'B'. Eucalyptus as a species are also particularly vulnerable to wind

throw which will direct future management in the future and limit its

wider amenity value.

[chrism3513]

Picky but good point. I doubt it would get you far with the PINS inspector.

 

 

 

Eucalyptus gunnii or cider gum is the species. i.e. the full name.

 

 

 

What people usually refer to as the species (i.e. gunnii) is actually correctly termed the specific epithet.

 

 

 

 

 

Windthrow is failure from the rootplate during storms.

 

 

 

Cheers

 

 

Thanks , it's not a term Iv heard before

[jaime bray]

It would appear that the surveyor has discounted remaining contribution in years within his assessment, and read the wording trees of low quality, and added this to trees with no material conservation or other cultural values. Hence the comment about low bio diversity to native species, which isn't entirely true. It's all subjective though, so bogging down I'm such detail is not worth doing. What is worthy of your attention is creating pictorial reference of the tree in association with the development.

 

How close to the boundary is the tree? What's the actual over hang of crown onto development site? What are the levels of the site like? I ask the latter as it may be worth you making note of chemical use on site and the leakage of that into the root system of your trees. If there land drains towards yours, then keep an eye on this. With root severance and then chemical uptake it could significantly contribute to the demise of your trees condition.

Edited July 2, 2015 by jaime bray

[benedmonds]

Hi

 

I'm not sure the tree assessor has got it wrong. If you follow the guidance

......

 

In conclusion, the tree is British Standard BS 5837: 2012 Trees in relation to design demolition and construction - Recommendations category C1/C3

 

Ed

 

Makes sense to me..

[Thehardwaremonkey]

Thanks for this information folks, it's reassuring that it's not entirely cut and dry to assess.

Surprisingly I'm finding it all way more interesting than I expected.

I understand how you have worked down through the chart but I think perhaps it's the statement associated with category c trees that serves to confuse - which says:

Category C

Trees of low quality with an estimated remaining life expectancy of at least 10 years, or young trees with a stem diameter below 150 mm.

The tree is not low quality, I don't think so anyway, I see no defects, I believe it will last way longer than 10 years and stem diameter exceeds 150mm by quite some way.

I have assumed that the assessor is correct in the estimation of the tree height but I'm not sure if this is all that significant in the categorisation - say I measured it at 18 metres...

 

If it is category C, does that make it less relevant to protection than say a B3 or a B1, I'm not clear on this aspect.

Edited July 3, 2015 by Thehardwaremonkey
Fat fingers

[jaime bray]

It says at least ten years, not up to ten years.

[Thehardwaremonkey]

Weird that I didn't absorb that info before, thanks.

Sorry, I forgot to reply to your questions before...

How close to the boundary is the tree? It is about 500mm from the nearest point of trunk (Do we say stem?!?) to border.

What's the actual over hang of crown onto development site? Maybe 3 metres?

What are the levels of the site like? Maybe equivalent to mine, it's fairly level between my garden and theirs.

[daltontrees]

There is no difference in the weighting attached to the sub-categories. A is A, as is A1, A2, or A3. All carry the same weight. BS 5837 para 4.5.4

 

It's also worth noting that categories B and C sub-group 2 relate to trees present in numbers/groups/woodlands, not individuals.

 

Ed

 

Yes, I just don't think I explained this very well. For every tree a surveyor is not just faced with a choice of A, B, C or U, but with a preliminary choice of 1, 2 or 3. So a free-standing veteran that is ghastly looking and not providing much amenity could be considered a low grade 1, not a 2 at all, and a high grade 3. I have always gone on the basis that if I have 2 choices, say C1 (low arboricuktural value) and A3 (high conservation value) then I must choose A3.

 

In the case of the OP's tree, the surveyor has chosen 3 (conservation) and then given it a low subcategory (C3) because Eucalyptus is not native. A low subcategory might well be right for conservation value. However, if it is a perfectly good arboricultural tree in a garden, it should also have a A1 or B1 value.

 

So what I meant was A always trumps B always trumps C (stating the obvious). Given the choice, the tree should have been reported as A1 or B1, adn that even if it was in relally poor condition because of root damage it shoudl have been reported as C1 rather than C3.

[daltontrees]

Hi

 

I'm not sure the tree assessor has got it wrong. If you follow the guidance and start at U, see BS 5837: 2012 para 4.5.5. We can all agree it's not that.

 

Next we cascade down to A, see BS 5837: 2012 paras 4.5.3. The tree has not only to meet the category definition but also one of the criteria. It's not rare or unusual, and at only 12m tall hardly a particularly good example, neither is it an essential component of a group or formal or semi formal feature, not A1 then. As a small tree in a garden it won't be of particular visual importance as a landscape or arboricultural feature, not A2 then, and it has little conservation value and no cultural value, not A3 then.

 

Therefore at best its a B. It's not B1 because of downgrading due to defects, it has no collective merit, not B2 then, and no material conservation value, not B3 then.

 

Therefore it must be a C. As a small tree in a garden with limited merit it would qualify as C1. Its not a member of a group, not C2 then. The tree has no material conservation value, or other cultural value so it would qualify as C3.

 

In conclusion, the tree is British Standard BS 5837: 2012 Trees in relation to design demolition and construction - Recommendations category C1/C3

 

Ed

 

I'd have to disagree on that based on the evidence we have. Eucalyptus are realtively unusual in this part of the country. it has a 20+ according to the surveyor. Size is unimportant to subcategory. You say "It's not B1 because of downgrading due to defects" but even the surveyor says it is 'good' and has 20+ left. It therefore has to be a B1.

 

The surveyor seems to have a tail that is wagging a dog.

 

And in the end the LPA will hopefully come out, look at it and decide whether the surveyor is at it or not. Based on the limited description we have, I'd say the report's credibility would be in doubt from that point onwards.

[benedmonds]

The surveyor seems to have a tail that is wagging a dog.

 

Not at all. Classifying a neighbours tree as C is going to have no effect on a development! It will still require the same protection as an A category tree.

 

Classifying trees as A,B, C or U is obviously limited, but if you are classifying all your run of the mill trees as A's or B's there is no differentiation. The aim of an AIA IMO is to help a designer decide which trees are worth keeping and how much space they require. If you don't differentiate the ones worth retaining with the "unremarkable" then how can the designer make an informed choice?

[kevinjohnsonmbe]

Classifying a neighbours tree as C is going to have no effect on a development! It will still require the same protection as an A category tree.

 

 

That's what I'd been thinking, surely since it's not in the ownership of the prospective developer, it's not within their gift to "do" anything to the tree other than that which crosses the boundary.

 

It's a funny old game, such knowledgable folks, using a common system, arriving at such different conclusions (mindful of the limited info.)

 

We're all doomed!