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Tree assessment is looking up

Thursday, May 12, 2016

Arborists experienced in preparing reports in support of planning applications will be familiar with BS5837:2012 Trees in Relation to Design, Demolition and Construction – Recommendations.

As regional head of arboriculture at Thomson Ecology, I, along with other arb professionals, recently attended a two day seminar at Myerscough College hosted by Barrell Tree Consultancy. The purpose of the event was an advanced consideration of tree assessment for planning.

We all know that trees are a material consideration when it comes to planning. When do they become a constraint though? The day starting with a review of categorising trees. In simple terms, trees can be placed into one of four categories: high quality, moderate quality, low quality and unsuitable for retention. Using the BS5837:2012 methodology, these would equate to A, B, C and U Category trees. Tree categorisation is subjective, however. What one person thinks of as being a good tree, another may disagree with and rate it as low quality. A debate over the category of a purple-leaved plum led me to conclude that the consensus among arborists was that they really don’t think much of them!

Some trees, however, can be quickly assessed and shoehorned into a small box, metaphorically speaking, in a Tree Schedule. Veteran trees - Category A. Trees with less than 10 years’ safe useful life expectancy – Category U. Category C trees would normally be considered so because justifiable reasons would prevent it being retained for more than 10 years. In very general terms, this equates to reasons of size, poor health, excessive nuisance and good management. Young trees less than 10 years old or less than 10 metres in height fall into Category C. Category B trees, it was suggested, are all the trees that are left and would be worthy of legal protection. Particularly high quality trees would be promoted to Category A as would trees that have the potential to become very large.

Having sorted out tree categorisation, the group had a go at determining some of the trees within the College grounds. Seasoned surveyors soon scratched their heads as gut feelings were questioned. Is it a B or just a C? Can that really only be a Category C? Would you really put a TPO on that?

BS5837:2012 was further questioned for suitability, and with a review of the document due in the not too distant future, some of the problems with it were discussed. This was not about a new method of categorising trees though, just a different way of approaching it. I for one found the day very informative, and I’ll certainly be incorporating some of the ideas into my reports.

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