Tree
Micro-Ecology: Perceptions of Disease & Decay in Trees
Interpreting the Significance of Factors Affecting
Tree Structure & Health
(Southern Venue) 23 & 24 May 2005: Pembroke Lodge, Richmond Park, Greater London
(Northern Venue) 26 & 27 May 2005: Fountains Abbey, Ripon, N. Yorkshire.
 Arboriculture is a study and appreciation of organic living processes that are by their very nature dynamic, while some of these processes are in a constant state of flux. Considering this it is important to remember that ideas should not be ‘rubbished’ for not conforming to current thinking, even if they appear to contradict or ignore recognised theories in practice.
For example one oak tree may have experienced many different management ideas over its lifetime including: coppicing, pollarding, flush cuts, wound painting, cavity filling, cable bracing, target pruning, to mention just some of the more obvious.
We now prod and poke this tree with hammers and drills, while scanning its heartwood with electric currents and sound waves, concerned about its ‘safety’ and frustrated by our lack of knowledge about it.
Our understanding of trees and the arboreal ecosystem, of which they are part, is in its infancy. To develop and grow within arboriculture we have to expand our knowledge by exploring the world of trees. We must adopt a philosophy of working with trees and learning from them, developing our knowledge, understanding and appreciation, constantly aware of their longevity.
TREEWORK SEMINAR SERIES
A growing appreciation and to some extent realisation of the degree to which tree interact with other organisms within their living environment, has broadened the scope of arboriculture. In fact to understand tree ecology and physiology we have to consider aspects of mycology, zoology, entomology…not to mention biology, chemistry and physics, the list go on (and on).
It is this need for a multi-disciplinary approach that has inspired Neville Fay, of Treework Environmental Practice (TEP) to organise a series if seminars. The latest of which, Tree Micro-Ecology: Perceptions of Disease and Decay in Trees, was appreciated by over 100 delegates who attended two venues, Richmond Park, Penbroke Lodge, Greater London and Fountains Abbey, Ripon, North Yorkshire between May 23 and 27 2005.
When asked why he had invested so much of his own time and business resources into this venture, Neville answered: ‘why not?’ However, he then went on to say that this is ‘in fact the fun aspect of what we all do, learning from our experience and taking new ideas.
‘The ancient tree perspective is one that seems to ramify through everything I/we do. It offers a chance to look at things in a different or new way and to consider natural processes and re-apply these concepts to practises we’ve carried out over the years’, he said.
‘The other aspect is that is does seem as though we know very little about very important processes such as the complexity that is the living soil, the fungal-root environment, and pathogenicity, symbiosis and longevity.
‘A multi-disciplinary approach seems to be the best way to explore these areas of knowledge. I am not aware of any coherent or structured way in which this is occurring at present in arboriculture’.
THE DRIVING FORCE
A significant driving force behind the progress of arboriculture in the UK has been growing emphasis on tree condition surveys, tree hazard rating and risk assessment. On the positive side this has heightened a general awareness of trees, while concerns about tree safety have increased and funding opportunities for research and development of decay detection devices. However, there has been a tendency to think of decay as a negative thing and not consider the integral part it plays in the living processes of trees.
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Decay is a process that develops in stages
over a period of years, over decades and sometimes over centuries, during which time it offers a diversity of habitat for a multitude of different organisms that play an integral role in the arboreal ecosystem.
(Photo: Andrew Cowan) |
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Olaf Ribeiro uses high
pressure air tools to blow the soil off the roots of trees.
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We now have a diverse array of tools at our disposal that have been developed to satisfy our demand for knowledge about so-called tree defects. From the simplest that utilise our understanding of the reactive growth of trees to interpret morphological symptoms, others that make use of everyday hardware like hammers and drills, while some devices have been linked to computers that measure physical resistances or the passage of sound waves through wood, and more consider the physical stresses placed on the tree by its growing environment.
So in which system or device do we place our trust, and perhaps more importantly invest our money, because everything comes at a price? How can we be sure that this investment is worth it and do you get better or more accurate results by using the most expensive equipment? The answer is both yes and no, because any system or device is only as good as the person using it and interpreting the results, while it is also important to remember that each method of assessment has its weaknesses.
Context is everything! We must remember that each system or device has its share of limitations and situations where it excels, so the trick is working out which tool to use and at what stage. Remember no one method can be the ‘be-all and end-all’ so just making the decision of what method to use can be a job in itself. This is another reason why Neville Fay has worked so hard on his seminar series.
Neville: ‘This seminar series invites individuals in the front line of arboriculture to consider their work and approach within the context of the insights into trees growing in hostile urban environments and the complexity of influences that contribute to tree longevity or decline’.
‘It is our contention that in spite of a wealth of research, data and information, these processes are barely understood. This makes the seminar series and the work of arboriculturalists all the more interesting as all those activities involved in the field of arboriculture have a role in growing and sharing this with others’.
TEP’S TREE MICRO-ECOLOGY SEMINAR – HIGHLIGHTS
TEP had put together a very compact, in-depth programme covering the micro-ecology of the living soil, use of innovative devices for tree decay detection (thermal imaging and tree radar), and tree condition surveys in the UK and USA.
It was a privilege to hear presentations from some of the leading practitioners in these fields, from as far away as the US and Italy.
Dr David Lonsdale, as well as his excellent presentation ‘Towards a UK tree condition survey’, did a first-rate job of tying these presentations together and leading the discussions, while Neville Fay added a great deal of value through his chairing of the entire proceedings.
The presentations were fascinating, the debate stimulating and the general feel of the event friendly and relaxed, allowing the opportunity for delegates to discuss issues directly with the speakers during the breaks.
Dr Olaf Ribeiro, Ribeiro Plant Lab, USA
Some of the most inspiring presentations were given by Olaf Ribeiro and Mark Hoenigman (Mark a delegate at the seminar, also from the USA, gave a short guest-presentation at the Richmond Park venue).
These presentations extolled the virtues of concentrating on tree root systems and their growing environment within the living soil. Olaf Ribeiro has over 30 years’ experience of diagnosing plant health problems, and a specialist in Phytophthora sp. world-wide.
Mark Hoenigman had built a thriving tree care business, which specialises in root care and soil remediation used to treat tree disorders.
A series of papers were presented by Dr Ribeiro, who managed to pump an enormous energy and enthusiasm into the often neglected and over looked topic of soil micro-biology, with descriptions of his work, which have sometimes involved complete soil replacement about the root zone of trees.
He explained how they used compressed air to blow the soil away from entire tree root systems and replace it with a customised mix of soil that includes scientifically balanced nutrient and mineral levels, while also considering and introducing soil microbes as well.
Control of Phytophthora sp. was at the forefront of the delegates’ questions and Olaf was quick to emphasise that it was his opinion that the answer to its control was in healthy soil biodiversity. He used a great number of case studies, to illustrate his points, where he had saved trees that were thought to be beyond the point of no return.
It was a real illustration of how much we have to learn about the growing environment of trees, and that while tree management continues to concentrate on pruning we are often only dealing with the symptoms of the problem and failing to practice true tree care.
Ed Hayes, Safetrees, USA
Ed Hayes from Minnesota gave presentations based on information gained from the US investigations into the incidence and cause Sudden Branch Drop and the potential value of the establishment of a tree failure database. The value of a tree failure database was given in a UK perspective by David Lonsdale who presented the pros and cons of such a system.
The system currently being used in California provides a record within a research database of references relating to species’ specific information on growth and decay characteristics which can be statistically analysed. However, the system is currently limited by the quantity and quality of the information available for analysis within the database.
It is hoped that once established the system will be able to help species selection when planting, (i.e. identifying trees that may be more prone to failure, which would be considered unacceptable in a well-used area with high value targets). It could also help with tree management by informing pruning regimes where formative pruning may be used to reduce chances of failure occurrences in the future, e.g. pruning out multiple or co dominant leaders with tight forks.
Some cautions were expressed during questioning and the seminar debate, regarding the limitations of such a system, which only looks at trees that have failed and has no control mechanism considering trees that have recognised that the system would have many advantages and could be proactively used to improve tree population management.
Giorgio Catena, Catena & Thermography, Italy
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Giorgio Catena.
(Photo: Andrew Cowan) |
Decay detection devices are a hot topic in arboriculture at the moment and Giorgio Catena, a leading expert in thermal imaging, gave three presentations including a practical demonstration to put forward a case for thermal imaging cameras. Although he was uncertain as to why in all case studies the equipment was able to register the presence of decay and cavities in trees, in his case studies and those of his daughter (a practising arboricultural consultant in Italy) consistently proved positive.
Examples were presented where trees had been assessed using the thermal imaging camera and subsequently felled to be cut up to reveal decayed areas. As part of his trip to England Georgio was meeting with a research specialist based as Nottingham University to start a project that will look at the reasons why thermal imaging cameras appear able to identify decay in trees.
Seminar Proceedings
The proceedings of this seminar will eventually be edited by David Lonsdale and published in the Arboricultural Journal. Those who were unable to attend this event and wish to obtain the speakers’ papers in their unedited version (as presented at the seminar) should contact TEP directly.
PROPOSED FUTURE SEMINARS
This seminar was developed and implemented by TEP and co-sponsored by the Arbicultural Association. TEP intends to continue to develop partnerships to collaborate with future seminars that will explore interests within the practice and respond to those that have expressed a wish to use the seminar series to clarify current issues that are arising in arboriculture.
For example TEP have been exploring the ideas behind the so called ‘Pulling test’, more formally known as the Wind Load Simulation Test, that has been in use across Europe for nearly 20 years. The test is part of the ‘Statics Integrating Assessment (SIA)’ method originated by Lothar Wessolly of the University of Stuttgart, and involves the application of a small, precisely measured load to the tree in order to evaluate the disposition of the trunk to break, or the tree to uproot.
There are two ways in which TEP propose to approach this particular subject, which is a hot issue at present in context of recent articles and publications. TEP propose to base a practical workshop around specifically identified trees that one or more local authorities wish to have the pulling test applied to. The exercise will be completed, as it would be in a standard evaluation using the SIA method. This will then be used to teach the method and explore its value and how we can best interpret the information derived from the procedure.
It is anticipated that the event will be limited to around thirty participants and therefore will be arranged on a ‘first come first served’ bases. The key presenters at this practical workshop will be Dr Jaroslav Kolarik, a leading arborist in the Czech Republic and Dr Petr Horacek, Head of Wood Science at Brno University, Czech Republic. Possible dates for this practical workshop are the end of July and mid-October of this year. Those who are interested should contact TEP as soon as possible to reserve a place.
TEP also intend to follow this with a two-day master class in Wind Load Simulation in Trees (Management for Extreme Climatic Events). This would be particularly interesting to those who want to understand further the concept behind tree statics as practised in mainland Europe, and would include case histories regarding its application in different contexts as well as factors involved in load analysis and device-supported techniques for evaluating tipping and breaking resistance in trees. This event is scheduled for of 2005.
In November TEP will be holding a seminar entitled Life Within & Beneath the Tree. This will explore interactions between roots, soil and microorganisms that are part of the co-evolutionary processes influencing tree physiology and health. This will look at mycorrhizae, wood decomposers, soil structure/condition, bacteria and nematodes as a basis for indicators of tree condition, pathology and remediation (before interfering with the above-ground tree).
For the spring of 2006, the practice will present a seminar on Tree Morphology. This will explore the methodology, mainly developed and used in the Continent, that views the tree in terms of standard development morphology. This system is based on the assumption that the physiological and environmental history of the tree is somehow recorded in its form. Variations from a norm may be in interpreted in terms of perturbations in physiology and health. The system is used to understand the ageing process, physiological stress and diagnostic technique to determine tree management.
It is intended that Pier Raimbult or one of his colleagues will be a guest speaker at this event to explain his thesis on the subject.
FURTHER INFORMATION/CONTACTS
Information, including presentations, articles and programmes for past, present and future seminars and workshops held by TEP can be found here: Tree Seminars or by emailing seminars[at] treeworks.co.uk
Booking forms for current seminars are also available from the web site. For further information, you could also call TEP on 0117-9105-200
Olaf Riberio – www.riberioplantlab.com
Email: fungispore[at]comcast.net
Ed Hayes – www.safetrees.com
Ancient Tree Forum: www.ancient-tree-form.org.uk
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