Profile cover photo
Profile photo
Arbor Vitae Arboriculture Ltd (AVA Ltd)
4 followers -
Expert Arboricultural Consultancy & Services
Expert Arboricultural Consultancy & Services

4 followers
About
Posts

Post has attachment
+Arbor Vitae Arboriculture Ltd (AVA Ltd) will be closed for Christmas from Tuesday 23rd December until Sunday 4th January inclusive (checking emails intermittently).

Feel free to email us any enquiries over the festive season and we will respond as soon as we can. http://www.avtree.co.uk 
Add a comment...

Post has attachment

Post has attachment

Post has attachment
+Mike Charkow gained the Certificate for ‘Bats & Tree Related Works Guidelines & Survey Methods’ in May 2012, awarded by +Echoes Ecology Ltd. Find out more:
Add a comment...

Post has attachment
Looking at a sample of compacted soil at a development site.
Add a comment...

Post has attachment
The Wilfred Owen Violin

I was lucky enough to be asked to carefully remove a branch from a Sycamore at Napier University Craiglockhart Campus, where Wilfred Owen and Sigfried Sassoon convalesed during World War I.

The Edinburgh violin maker Steve Burnett - creator of the famous 'Sherlock Violin', wished to commemorate the 100th year of WWI by making a violin from a branch of a tree growing in the grounds of the former Craiglockhart Hospital; the tree chosen was a Sycamore that would have been growing when the war poets were residing there, and would have been seen by them from the hospital windows.

Listen to the story on Radio Scotland, 'The Sycamore Sings: The Wilfred Owen Violin'.

The programme is aired on Monday 4th August at 11:03-11:31, and repeated on Wednesday 6th August at 13:32-14:00 and Thursday 7th August 05:02-05:30.
http://www.burnettviolins.co.uk
Burnett Violins
Burnett Violins
burnettviolins.co.uk
Add a comment...

Review of the recent Experts Question Time event held at Royal Botanic Gardens Edinburgh with Jeremy Barrell and David Lonsdale, hosted by the Consulting Arborists Society.  This was a very informative day for professional consulting arborists.  Text by Mark Chester of CAS.
_____
On Tuesday 1st July, some 60 tree care professionals gathered at the Royal Botanic Garden, Edinburgh for this seminar co-presented by Jeremy Barrell and Dr. David Lonsdale.  The event was a ‘first’ on several fronts, being the first time that the Consulting Arborist Society has organised such a seminar, the first time to deliver a seminar in Scotland, and the first time that Jeremy has spoken to a Scottish audience.

The venue was excellent, and after a welcome from the curator, Jeremy began his first presentation.  Whilst the overall theme was the same as the event held at Kew Gardens in June 2013, exploring the issues of risk management with trees, the presentations had been refreshed, with updates on events over the past year.  Jeremy began by referring to the loss of canopy cover across the UK.  This, he suggested, was due in part to arborists taking the ‘better safe than sorry’ approach when faced with trees and balancing retention with risk.  There tends to be a preference to fell a tree rather than risk the consequences if it fails.  There are alternatives to felling.  Throughout, he encouraged the audience to think afresh.

He then reviewed the main risk assessment methods available to the modern arborist, looking at the ISA’s Best Management Practice on Tree Risk Assessment, the work of Matheny and Clark, the QTRA approach and the THREATS system devised by Julian Forbes-Laird.  One of the problems we are facing is that there is a focus on probability.  The courts tend to have little interest in this, but in whether the failure of a tree, or part of a tree, is foreseeable, and if it is, what action is taken to reduce or remove the risk of failure, and whether the action is proportionate.

As explained in his recent paper published in the Arboricultural Journal Balancing tree benefits against tree security: The duty holder's dilemma (http://www.tandfonline.com/doi/full/10.1080/03071375.2012.691674#.U7VtW2dOVOw) a defensible approach must consider the level of occupancy, the type of inspection and have a built-in review process.

Finally, Jeremy looked at how we can manage trees prone to weather-related failures, such as Cedars.  One of the management challenges that he has observed with Cedars is that the branch structure tends to be ‘flat’ with dense foliage so that snow can easily accumulate.  This makes them vulnerable to snow damage, which often results in catastrophic failures requiring trees to be removed.  Careful reductions in the branches, aimed at reducing weight, can be a successful management technique for extending the length of time that mature trees can be retained.

He then looked at a Liriodendron which was introduced from Virginia in 1685 and so is historically important.  This is a substantial tree which has been ‘topped’, and has survived recent storms which may otherwise have had a more severe impact on it.  There is a real importance in retaining historic trees, even, on occasions, when dead, as this can provide a link to the past.

Dr. David Lonsdale spoke next and  identified the need for the tree manager to take ‘reasonable steps’ to manage risk.  These include the following: the procedure for inspecting trees, the training and competence of inspectors; the implementation of inspection and of appropriate  record-keeping; undertaking remedial action, with timing commensurate with risk.

Another requirement, which had been highlighted in some of the cases that David has worked on, is a clear demarcation of duties and responsibilities for those involved in the process.  Misunderstandings over the roles of individuals or contractors can contribute mishaps and liability, he cautioned.  Questions that are likely to be asked in court include the following: was an inspection system in place?  Was it sufficient?  Did the tree concerned show signs of requiring more attention?  Was remedial action needed?  If such action was needed but not  implemented, why not?

David then showed examples of published guidance on risk assessment and management.   With regard to the general principles, he explored some of the strategies for managing risk, including ‘assume it will never happen’, ‘it must never happen’ (an unrealistic approach) and keeping risk ‘As Low As Reasonably Practicable (ALARP)’.  With particular regard to trees, he explained how risk can be assessed using quantitative methods (such as QTRA), qualitative methods and semi-quantitative methods, all of which take account of the site-specific questions that one should consider: occupancy by people and property, magnitude of the hazard from potential tree failure and probability of failure.

David considered the pros and cons of various tree risk assessment methods.  He regarded quantitative methods as the most transparent but he acknowledged that they can sometimes create a false impression of accuracy.  He pointed out, however, that the same quantitative principles are cryptically embedded in matrix-based quantitative methods (such as the ISA’s Best Management Practice on Tree Risk Assessment). Also, he mentioned that there are other methods, such as THREATS, that do not, in his opinion, fully address the fundamental principle that risk can be assessed only with reference to a given period of time (e.g. one year).

David then spoke about various tree-characteristics that can indicate a propensity for failure.  In this context, he cautioned that, although the presence of a decay fungus should in certain circumstances be regarded as an indication of the need to investigate further, it is not a valid basis for decision-making.  He also showed some examples of ‘what not to do’ by way of making trees more hazardous. Finally, he showed some examples of highly valuable veteran trees, as an illustration of the need to manage risk in a manner that does not unduly detract from value.

During the lunch break, delegates were able to explore the range of decay-detecting equipment provided by the event’s main sponsors, Sorbus International.

In the afternoon, Jeremy spent time exploring the various tree-related cases that have gone to court in the past decade.  He identified that only about one in ten cases he deals with ends up in court.  Out of court settlements tend to be confidential, with little feedback.

One of the overriding themes of the cases Jeremy explored is that, based on the handful of published cases[D1] , claimants have tended to be unsuccessful with their claims, the exceptions being Poll (2006) and Battley (2013).  He then explored the facts relating to the recent inquest in connection with a fatality at Kew Gardens.  This was an inquest with a jury (not a civil prosecution), and so was not adversarial.  There was recognition that branch failure caused the fatality, the main issue being what caused the branch failure.  The jury concluded that there was insufficient evidence on the cause, delivering the verdict of accidental death.

Jeremy then went on to explore the primary and secondary causes of Summer Branch Drop, which had been implicated in the Kew inquest, and how to manage it.  He is hoping to publish a paper on this subject later this year.  However, management should focus on species known to be vulnerable, and individual trees that may be susceptible.

Finally, he explored how we can manage mature Cedars.  This includes identifying vulnerable trees, assessing the levels of access and whether the tree has sufficient vigour to be able to tolerate pruning.  Subtle pruning is often an effective management strategy, aimed at reducing the weight at the end of branches.  He concluded by showing photographs of a Cedar in the grounds of a school as an example of what can be achieved.  The tree had been recommended for removal by arborists, but the school was keen to retain it because of its heritage value.  He had proposed a programme of pruning and fencing as an alternative to removal, and that is what has been done, allowing the tree to be enjoyed by future generations.  There was much more that Jeremy could have shared, but the clock had beaten him.

David continued his presentation with some casebook examples, illustrating the key issues that can decide the outcome of a court case. These usually relate to  the key factors that need to be taken into account in tree risk assessment: site occupancy, magnitude of hazard and probability of failure.  He mentioned also that the level of competence of tree inspectors has also been important in various court cases, pointing out that the courts do not generally expect inspectors to know more than they can reasonably have learned from courses, textbooks and experience ‘on the job’.   David also explored the differences between cases being considered as civil claims, criminal prosecutions and by a coroner.

There can be a tendency, when dealing with the aftermath of a tree failure, to explore what went wrong with the benefit of hindsight.  He cited a case where a Beech tree had been identified for removal by a local authority, and a works order raised.  The work required a road to be closed, which slowed the process.  The work was programmed for three months after the inspection.  One week before the planned works,  the tree failed, causing a fatality.  Was this just an accident, unfortunate timing?  The balance of evidence was probably somewhat in favour of the Defendant and there was a modest out-of-court settlement.

David then cited work by Prof. John Adams, who has explored the almost infinite range of events that might or might not occur according to foresight, as compared with a particular sequence of causal events that can all too easily be identified in hindsight after an incident has occurred. David cautioned that this is not helpful, and is not within the remit of the arboricultural consultant.

In the context of foresight and of hindsight, David showed examples of various kinds of forks and branch attachments, the inherent weakness of which can, in retrospect, be misleadingly portrayed as inevitable.

The final part of the day explored questions from delegates.  The issues of managing a large population of trees with limited funds, the level of inspection appropriate for a large population, and how much detail to record, were explored.  In addition, the management of veteran trees and the possible implications of summer branch drop, provided good discussion. On the latter subject, David explained that wood moisture content fluctuations probably play a part in branch failures that are attributable mainly to other factors, such as decay.  Summer branch drop is perhaps the correct diagnosis only where a change in moisture content is the key factor.

This event proved popular, and we were encouraged to return soon to explore another issue of importance to the arboricultural world.
Add a comment...

The prolonged spell of dry and hot weather may be taking its toll on your trees, especially id they are on a  shallow or sandy soil.  It would be a good idea to get some water to the roots of any trees that are suffering.
Add a comment...

The unusually dry weather is causing some trees to wither: trees affected are mainly on sandy soil (which does not hold water as well as other soils), or trees with limited rooting or compacted areas.  A good layer of wood-chip mulch around the base of the tree will help to retain moisture and add organic matter to the soil.  We are happy to advise and to provide this service.
Add a comment...

Post has attachment
Home owner and tree surgeons fined for felling protected trees.
Add a comment...
Wait while more posts are being loaded