A Week of Tree Surveys Across Northern Ireland and Ireland

Five days, five very different jobs. What each one involved, what the trees told us, and why the cheapest advice of the week was to do nothing at all.

Written by John McNamara, arboricultural consultant, McNamara Tree Consultancy. A VALID Accredited Validator who also holds Professional Tree Inspection (PTI) certification and is an Associate Member of the Arboricultural Association. View John's qualifications and experience

September has been a busy month. As well as helping my four-year-old settle into his new school routine, I have been all over Northern Ireland and Ireland surveying trees. Here is one week of it, day by day.

Monday: ash dieback on a commercial site in Kells

Monday took me to Kells, outside Ballymena, for a tree risk assessment on a commercial premises. The main issue on the site was Hymenoscyphus fraxineus, better known as ash dieback, which had progressed a long way in a number of the ash specimens.

Ash dieback is now the defining problem for ash across Northern Ireland and Ireland. The fungus kills the leaves and shoots first, then works into the branches and eventually the stem, and as the wood dries out it becomes brittle. On a commercial site that matters. A dying ash beside a car park or a delivery route can shed limbs without much warning, and the advanced cases become dangerous to climb, which limits how they can be dealt with later. The earlier a diseased ash is identified and a decision made, the more options the owner has and the cheaper those options tend to be. Our guide to ash trees explains the signs to look for.

Back in the office I prepared the report and a bespoke Tree Management Plan. I would encourage every commercial client to ask for one. A risk assessment is a snapshot, and trees change between visits. The plan gives the client a simple way to manage their remaining tree stock between official inspections: what to watch, what a change looks like, and when to call. That is what a duty of care requires.

Tuesday: a BS 5837 report for a development in County Meath

Tuesday was an office day, spent completing the final report for a development project in County Meath. This report is known as an Arboricultural Impact Assessment, or a "BS 5837 report" to some, and its job is to tell the local planners how the proposed development may come into conflict with the trees on and around the site, and to propose mitigation measures that reduce those conflicts.

The report is often misunderstood as a list of trees to remove. It is not. The survey records each tree and grades its quality. The constraints plan shows the root protection areas and the space each tree needs. The impact assessment then overlays the proposed layout and identifies where foundations, drainage, levels or access would damage roots or crowns, and the mitigation section suggests how to avoid that: moving a building line, using a no-dig surface, protective fencing during construction, or, where a poor tree is in the way, accepting its loss and planting properly in return. A planner can see that the trees have been considered, which is what gets an application through validation. If the terminology is new to you, our article on BS 5837 explained walks through it, and the BS 5837 tree survey page sets out the deliverables.

The standard is used on both sides of the border, and Irish local authorities expect the same evidence.

Wednesday: a rural property in Killinchy

Wednesday was a straightforward risk assessment on a rural property at Killinchy, near Newtownards. A number of defects were observed on the client's trees.

This may feel counter-intuitive, but defects are just one part of a proportionate risk assessment. In addition to analysing the health and structural condition of a tree, we also look at the area in which the tree might fall, quantifying it in terms of occupancy. Finally we work out the likelihood of failure: is it at immediate risk of failing, or is failure very unlikely?

If a tree has a defect that is likely to fail imminently and it is situated at the side of a motorway, it has to go. If however, as was the case in Killinchy, the affected tree is at an elevated risk of failure but is only going to fall on disused scrubland when it fails, the level of risk is acceptable.

In this case my recommendations promoted biodiversity by leaving the trees standing, and they saved the client a considerable sum in unnecessary work. The survey was priced at £350, as opposed to a possible £14,000 in unnecessary tree works. That is the benefit of appointing a qualified and independent arboricultural consultant who is not motivated by turning a profit on tree works. Our article on who is liable when a tree falls explains why a recorded assessment protects the owner as well as the trees.

Thursday: a protected tree in Ballinderry Lower

Thursday I inspected a tree in Ballinderry Lower for a client who wants it removed. The tree is protected by a Tree Preservation Order, so removal without consent would be an offence.

Following the inspection I completed a Tree Works Application, with a replanting plan, and submitted it to Lisburn & Castlereagh City Council. The application sets out the condition of the tree, the justification for the work and the replanting proposed. If you are unsure whether your own tree is protected, our article on planning permission to cut down a tree explains how to check.

Friday: VALID risk assessment for Ards and North Down Borough Council

Friday took me to Comber to carry out a VALID risk assessment on behalf of Ards and North Down Borough Council. This is part of a longer-term project aimed at enabling the council to map its tree stock and manage the risk those trees pose proportionately and reasonably.

VALID is the method I use for every risk assessment, and proportionately is the important word. A council owns thousands of trees. It cannot fell every tree with a defect, and it should not, because the public benefit of those trees is enormous. What it needs is a consistent, defensible way of deciding which trees need attention now, which need watching, and which can be left alone with a clear conscience. Mapping the stock is the first step, because you cannot manage what you have not recorded. Assessing each tree by the same method is the second, because a decision made the same way every time is one the council can stand over if it is ever questioned.

Next week

Next week brings Tree Works Applications in Derry/Londonderry, Lurgan, Belfast and Lisburn, and a return to Comber to continue the council project.

Two of the five jobs ended with a recommendation to leave the trees alone. One ended with an application to remove a tree, with replanting. Two were about giving an organisation a system rather than a one-off answer. None of them involved selling tree work, because I do not sell any. If you are not sure which of these your tree needs, our article on tree surgery or tree survey is a good place to start, or send a photograph and we will get back to you.