BS5837: 2012 Trees in relation to design, demolition - Arboricultural ...

BS5837: 2012 Trees in relation to design, demolition and construction
AA Road show presentation notes: Richard Nicholson May-July 2012
Edited by Mike Sankus
Paragraph 4.4.2.9 – Provides information about shrinkable soils and hedgerows. This was
added at request of engineers
Paragraphs 4.5.3 & 4.5.7 - Tree categorisation no longer uses R as a tree grade and
includes U instead. The reason for using U and not R is that it removes any assumption that
R = Remove.
Paragraph 4.5.4 - Generally the same weight is accrued for each subcategory as before
(see below). The sentence "would not accrue added value" was present in BS 5837:2005,
but is no longer in the text. Effectively it’s the same as it was, but the Note is in the wrong
place in the process.
The note in BS 5837:2005 at the end of the table: "Whilst category C trees will usually not
be retained where they would impose a significant constraint on development, young trees
with a stem diameter of less than 150mm should be considered for location" has been
taken out of the standard and does not appear in BS5837: 2012 because Table 1 is about
gathering the data in order to make decisions, not about condemning a tree before all the
data has been gathered.
Paragraph 4.5.7 - Upgraded means it’s a U grade tree, based on 3 bullets, but its
conservation, heritage, landscape or cultural values make a case for it to be upgraded to a
C grade tree for the short term. This of course is subject to the safety issues also mentioned
in this paragraph.
Paragraph 4.5.8 - The reference to irremediable diseases applies to serious ailments, which
have a significant impact on the safety of a tree in the short term. For example Inonotus on
Plane or nail galls on a Lime shouldn’t downgrade a tree which would otherwise be graded
A, B or C to a U grade tree. The same logic applies to the third bullet point under U grade
trees in Table 1
Table 1 - Remaining life expectancy is used in BS 5837:2012, rather than ‘substantial’ or
'significant' contribution as in set out in BS5837: 2005. Trees can contribute when they are
dead. Trees graded A , B or C are largely about trees that are not dead.
OED Definitions –
Quality: Distinguishing characteristic, the character or nature of something.
Value: Desirability in respect of some property.
Paragraph 4.5.10 - Young trees were raised as being important by the review group in DPC
but there was no support for this view so it was removed.
Paragraph 4.5.11 – There is a definition of veteran in paragraph 3.12 which is taken from
BS 3998: 2010. The importance of veteran and ancient trees is highlighted here. Both are
classed as A3 grade trees because there was a feeling that an ancient, largely dead tree
could, under BS5837: 2005 could too easily be classified as an R grade tree.