TREEL NE
The International Society of Arboriculture UK and Ireland Chapter Official Magazine Autumn 2013
This issue includes:
Frank Rinn’s Shell Wall Thickness and Breaking Safety of Mature Trees, Exceptional Yew Trees of England, Scotland and Wales, and
From the Treetops, a TCC and ITCC overview
Contents Editor’s Comment Dear readers,
3 Editor’s Comment A few words from Charlotte McDermott 4 Executive Director’s Say A few words from Ian McDermott
This is a picture of me from the ITCC on Centre 6 Events Calendar Island in Toronto, which Notable events for this year was a fantastic TCC to say the very least. Toron7 Contacts to was an amazing place The people to call with your queries - albeit insanely expensive... - and seeing our Features very own Jon Turnbull make it to the finals was 9 From the Treetops very exciting indeed. By Charlotte and Ian McDermott In this issue there is, once again, an interesting technical article from Frank Rinn, an account of Mark Johnston’s award, part two of Barrell’s perfect report search, an article on exceptional yew trees of the UK and an account of the ITCC in Toronto by yours truly. I would personally like to thank Ian McDermott, Russell Ball, Glynn Percival and Nigel Smith the four members of the editorial board - for continually supporting me throughout my time as editor, encouraging me and generally pointing me in the right direction! Thank you all.
12 The exceptional yew trees of England, Scotland and Wales by Andy Moir, Toby Hindson, Tim Hills and Richard Haddlesey 19 Shell-wall thickness and breaking safety of mature trees By Frank Rinn 25 Mark Johnston Press Release By Julie Gaier 26 Connecting People in the U.K. with Trees Mark Johnston Biography 29 In search of the perfect report Part II by Jeremy Barrell
— Charley
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Executive Director’s I always find writing these sorts of piece difficult so I looked to the archives for the last time I wrote in Treeline and was shocked to see it was the summer of 2007, hmm, time certainly does fly by when you’re not looking and not much inspiration from a piece over 6 years old, or maybe there is? In that last article I was talking about the Arboricultural Liaison Group (ALG) and the newly formed Arb. Policy Group. The latter was killed at birth by an overdose of lethargy and perhaps the reasons for the existence of that group were always a bit pretentious and perhaps the end was blessed. However the ALG tripped a few times in the recent past and was shelved for a couple of years but it is good to see it is back and functioning pretty well. The ALG is a forum for the terribly splintered arb. industry to come together around a table and talk about our commonalities and also to plan the calendars better so as events promoted by the member societies Bill Kowalczyk and Ian Morgan in Switzerland
do not clash too badly. The Chapter is represented by Jess Herbert (President Elect) and also the Municipal Tree Officers Association (MTOA) and the Consulting Arborist Society (CAS) both professional affiliations of the chapter are also represented on the ALG, so there is good ISA presence, and along with the AA, ICF, LTOA, Lantra and quite a few others the group is now vibrant with their next meeting scheduled for mid-October. If you want to know more about this forum please let me know and we’ll place some information into Treeline on a regular basis. The Summer has been pretty busy from an ISA perspective and damn enjoyable at times. We have had the UK&I TCC at Highclere, more of which is covered elsewhere in here and on the web, and that was just a great gig. Then ArborCamp at the JA Jones show. From there we were
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Say at the ITCC in Toronto and then onto the ETCC in Switzerland. Putting the “I” in ISA can sometimes be enjoyable as well as worthwhile as the venues and the climbing skills were some of the best have seen in years. One of the upsides was the road trip to Switzerland with Ian Morgan the current TCC Chairman and my old mate ex-President of the Chapter Bill Kowalczyk who was responsible in 1993 for roping me into ISA – a day that changed my life forever! It’s good to see that three 50 something’s can still get out and about without Saga insurance and a walking frame. The downside? You’re only as good as your next gig and we need volunteers to help make these things happen, so, you know the drill, contact us and make the offer, you never know where you’ll end up. For me though the highlight of the year will be the TRAQ course. I have been involved in the development of this qualification for over four years now and at times I found it to be one of the most frustrating experiences ever, but the result was worth the pain and I am really pleased that we have the first course right upon us now at Capel Manor on the 14th October and this will be the first
Bill and Stefan Kowalczyk in Switzerland
one in Europe and hopefully many more will follow. TRAQ (Tree Risk Assessor Qualification) is the ISA’s newest and shiniest award and is their first ever qualification as opposed to a certification. This may not seem much to us here in the UK but is a HUGE shift in the way ISA do things, another example of the “I” in ISA becoming ever more important. As you hopefully will have seen in the September 5-minute update, we have next year’s annual meeting set out and this is something you must put in your diary – 2nd and 3rd of May again at Capel Manor college (easy to get to and some cheap digs available). There will be a great array of things to do and see, so block the weekend out of your diary now, ring the family and have a great weekend. Mac
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Events Calendar Upcoming Events for the Busy Arborist
2013
September 7th-8th
ETCC, Switzerland
9th – 11th
Arboricultural Association Conference
12th – 13th Confor Woodland Show
http://www.itcc-isa.com/events/regional/etcc/ etcc.aspx www.trees.org.uk
www.confor.org.uk
http://www.treecentreopheusden.nl/expo/en/
October 1st – 2nd
Expo TCO
9th – 11th
ISA Leadership Workshop, Illinois
www.isa-arbor.com
12th
Certification Exam, Enfield
www.isa-arboriculture.org
14th – 16th Tree Risk Assessment Qualification
www.isa-arboriculture.org
November 24th – 2nd Dec.
National Tree Week
www.treecouncil.org.uk
7th – 8th
Tree Dressing Day
http://www.national-awareness-days.com/tree- dressing-day.html
11th
Hedgerow Regulations
www.mtoa.co.uk
December
Contacts Who’s Who?
Contact list for the chapter volunteers President
Alex Laver
President-Elect
Jess Herbert
Vice-Presidents
Bob Widd Vacant
Past President Editor Exec. Director Office Manager PA Reps CAS MTOA
Standing Committee’s TCC Ian Morgan SSA Stuart Phillips
Officers Rise for Research Russell Ball Tree Fund Glynn Percival Russell Ball Certification Dan Yeomans AFAG Alex Laver Charlotte McDermott Commercial Jon Tonks EAC Craig Johnson Ian McDermott Website: www.isa-arboriculture.org Jean McDermott Email: Enquiries@isa-arboriculture.org Tel: +44 (0)121 556 8302 Bob Widd Tim Wetherhill
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Phil Wade, Director – Sorbus International Ltd
Sorbus International Limited are leading suppliers of specialist & hi-tech equipment to the arboriculture, forestry, utility, grounds maintenance, landscaping & environmental care sectors in the UK & worldwide. In late 2012 the PICUS 3 was launched; the most compact, lightweight, fastest & user friendly PICUS system ever. The PICUS 3 hardware is a complete re-design & the result of this and the new Q73 software means time on site is effectively halved compared with previous PICUS systems. Quentin Nicholls, Managing Director of Arbortrack Systems Ltd comments: “After 10 years of getting to know the PICUS, it was time for us to take the plunge and buy the PICUS 3. The first thing you notice is the smaller case, which is now not much bigger than a standard briefcase. I found the PICUS 3 to be easier to use on site and there is no longer the need for a PC as the PICUS 3 will store the records of dozens of trees. The sensor belts are more streamlined & easier to handle & it also has built-in GPS and a clinometer to accurately measure the heights of trees. I would also thoroughly recommend purchasing the electronic callipers as these are simple to operate and considerably speeds up the time taken for each inspection.” Please contact Sorbus International Limited for more information on the PICUS 3 or go to our website www.sorbus-intl.co.uk
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From theTreetops A TCC Overview
By Charlotte and Ian McDermott The UK&I TCC After witnessing many a year of Jonathan Turnbull’s terrific performances within the UK & I Tree Climbing Championships, it was no surprise when – once again – he was selected as our male representative at the Internationals in Toronto, Canada. The Chapter competition at Highclere Castle was a raging success with some blazing sunshine mixed with the strong winds, but the latter did not deter the climbers from giving it their all, especially for the only female competitor in the competition, Josephine Hedger. With no other female competitor Jo chose and was given the chance to compete alongside the men and proved her worth in the tree industry when she won the Aerial Rescue event outright, but the results for the Masters climb placed her fifth out of the five males and herself, but as the only female she was automatically selected to go to Toronto in August along with the winner, Jon who was on very good form this year, read on.
The ITCC
Scott Forrest during the Masters
The Internationals took place on Centre Island, Lake Ontario, and attracted the public in huge numbers as well as the climbers, their friends, family and acquaintances. The climate for the ITCC was even nicer than that of the Chapter’s with uninterrupted sunshine throughout, so I’m sure some of the climbers had some sunburn to contend with in addition to the very demanding trees presented to them by the ITCC committee. Not so small stunted trees on this particular island and the spread of some of the trees made for great climbing as well as great viewing points too. The atmosphere was cheerful and optimistic, as it mostly always is, but for the finalists their optimism paid off and gave them
James Kilpatrick after his Masters climb
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all a glimmer of hope of becoming the Champion; for the five males, Giovanni Ugo, Scott Forrest, James Kilpatrick, Mark Chisholm and our very own Jon Turnbull, and the three females, Veronika Ericsson, Nicky Allen-Ward and Anja Erni, the Masters climb would come to prove who was the best of the best. Unluckily for our Jo, she didn’t quite make it into the final, but the word around was that she just about missed it – along with a couple of other climbers – by a fraction of a point. Better luck next time, Jo but there was a big consolation and Jo emulated her performance in the Aerial Rescue by winning the event in Toronto also. Unfortunately for Giovanni of Italy and Mark of America their climbs took a little too long and they both timed out, James’ climb was of a high standard but not high enough to compete against Scott and Jon. Scott’s climb was virtually perfect, which left Jon with a tough climb to compete against him, but in the end between these two fantastic climbers Scott once again came out on top and became the Champion, but Jon did the UK & I Chapter proud by representing us in the ITCC with his amazing climb which left him in a close
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Scott Forrest during the Masters
second place. The chapter continues to provide the opportunity to field such great climbers as Jo and Jon both nationally and internationally through sponsorship and a LOT of volunteer effort, we will always need extra help so please consider volunteering when the 2014 competitions come around. If you want to see Jo, Jo, and the other members of the UK&I European team (Stef Kowalczyk and Steve Gale) then you still can at the ETCC in Switzerland in early September. If that wasn’t enough, and you missed our last ArborCamp then our top climbers will be at the next ArborCamp at Capel Manor next spring – book early!
Left and above: Jon Turnbull, second place
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The exceptional yew trees of England, Scotland and Wales by Andy Moir, Toby Hindson, Tim Hills and Richard Haddlesey
SUMMARY While English yew Taxus baccata L. has become extinct or rare in many parts of Europe, Britain contains a large population of very large and old yew. We analysed 2,760 records of live yew trees to document this unique population and categorise by girth: 717 Veteran (5-6.99m), 204 Ancient (7-8.99m) and 55 Exceptional (≥9m) yew trees. Individual trees are mapped, and both areas and habitats of the highest proportions are detailed. The loss of 223 notable trees from churchyards highlights a need for better safeguarding a unique habitat of the world’s largest yew trees. Introduction English yew (Taxus baccata L.) is a slow-growing, long-lived (>1000 years), shade-tolerant species that is able to withstand full sun. In a continental climate it is typically an isolated understorey tree, but in oceanic climates it can form dense stands (Thomas and Polwart, 2003). Over-use in past centuries, combined with unsuccessful regeneration, browsing pressure, illegal cutting and lack of appropriate management strategies (Svenning and Magård, 1999; Dhar et al., 2006), have contributed to English yew being catalogued as a rare and endangered species over Europe (Hageneder, 2007).
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In Britain yew is widespread, although yew woodland is restricted to the south and, to a lesser degree, the north of England, occurring on shallow, dry soils, usually on chalk or limestone slopes. Thomas and
Polwart (2003) show the distribution of English yew in Britain. The Joint Nature Conservation Committee (http://jncc.defra.gov.uk/) lists thirteen yew woodlands of Special Areas of Conservation (SAC). A large population of individual trees and small stands are more widely spread, growing on more fertile soils. Yew has been comparatively little studied, probably because it most often occurs as a codominant or subordinate species in other types of woodland, or as single trees (Tittensor, 1980). Ecological investigations have been carried out on the yew woodlands on the North and South chalk Downs in south-east England (Williamson, 1979; Tittensor, 1980; Rodwell, 1991), but little has been published about woodlands on the magnesian limestone in Country Durham or on limestone pavements around Morecambe Bay. Age and dendroclimatological studies have been conducted on yew trees in the Privy garden at Hampton Court (Moir, 1999), woodland at Happy Valley (North, 2000) and some
churchyard yew in the south-east region (Moir, in preparation). The natural distribution of yew in Britain is clouded by planting. The only significant stand in Scotland, on Loch Lomond, is considered to have been planted, and whether yew is native to Scotland has been debated (Dickson, 1994). Particularly large yew trees that often occur (presumably planted) near chapels, churches, cemeteries and other prominent areas have long been of interest, and their occurrence, and often girth, documented. The aims of this research were to use records of a unique relic population of large-girth yew trees to quantify and map the population, to identify the most important areas and habitats of survival and to highlight recent losses. Methods The earliest locations and descriptions of ‘notably’ large-girthed English yew come from a variety of documentary sources, some dating back to the late 18th century. Since 2005 historic records, together with more recent identifications Figure 1. Ankerwyke, Berkshire, recorded with a girth of 788cm. (Photo: Tim Hills)
Figure 2. Frequency histogram of the girth of 2,208 live yew trees. and girth measurements of notable yew trees, have been collected by members of the Ancient Yew Group (AYG) and volunteers, and entered onto the AYG database. With most historical records now entered, the focus has turned to locating new notable yew trees and identifying where trees on previously recorded sites have been lost. The AYG database, which may be viewed at www.ancient-yew.org, provides the most comprehensive archive
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of information on large yew trees in this country. Tree girth has traditionally been recorded at breast height (1.3m). However, the trunks of yew are notoriously irregular (Figure 1), and low branches can make girth measurements extremely difficult, except when taken very close to the ground. The girth measurements of yew trees are therefore typically recorded at the minimum girth between the ground and breast height. Data For this study data from the AYG database was made accessible and retrieved in 2011. Seven fields of information: Site name, Area, Country, Site type, Tree Girth, National grid reference (NGR) and Notes, were transferred to a spreadsheet that was then edited, mainly to complete omissions, but also to help identify and correct errors. Girths recorded in inches were multiplied by 2.54 to convert to centimetres. National grid references were generally recorded to six figures, which gives a precision of 100 × 100m. However, where references were not recorded the NGR for the location name (typically the nearest village) was used. In most instances, where a few large yew trees occur in a small discrete group, only a single entry for the largest tree was recorded. To enable the distribution of yew to be plotted with ARCVIEW GIS software, NGR grid references were converted to latitude and longitude in a decimal degrees format. Records in the database for yew in Ireland and France are not in the British NGR format, so these records were not included in this analysis.
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In Britain both the Tree-Register and Ancient-tree-hunt.org.uk categorises trees into ‘Notable’, ‘Veteran’ and ‘Ancient’. However, to highlight the exceptional rarity and importance of the largest-girthed yew, we have defined a further
category ‘Exceptional’ yew. Here we define five categories based on girth: Young (≤2.99m), Notable (3-4.99m), Veteran (5-6.99m), Ancient (7-8.99m) and Exceptional (≥9m) (Table 1). The 30 counties with the largest populations of yew were listed in rank order. The percentage loss of trees has been calculated using the following equation: (Lost/Live)*100. Results A total of 3,041 records of yew trees were used in this analysis. Of these, 73% were of known girth, 18% of unknown girth, and 9% were lost trees. Distributions of the sizes of the 2,208 live yew of know girths are shown in Figure 2 and Table 1. Veteran, Ancient and Exceptional status yew trees form 32%, 9% and 3% of the records, respective-
ly. Just 35, 19 and one Exceptional yew trees are identified in England, Wales and Scotland, respectively. The overall geographic distribution of yew is shown in Figure 3 and quantitatively described in Tables 2 and 3. England is shown to contain 71% of the population of recorded yew, with the highest proportion at 17% in Hampshire and Kent. Hampshire and Kent between them contain 19% of the Ancient and 15% of the Exceptional yew trees. Wales contains 25% of the live recorded yew, but half this number (12% of the total population) is located in the County of Powys. Powys contains high proportions of both Ancient and Exceptional yew, accounting for 22% and 15% of these populations, respectively. Two other noteworthy
Figure 3. The distribution of 717 recorded yew of Veteran (black/small), Ancient (green/medium) and Exceptional (blue/large) size in England, Scotland and Wales.
high proportions of yew in England occur in the counties of Somerset and Gloucestershire in the South-west and in Shropshire and Herefordshire of the West Midlands, which contain 19% of the total population divided equally between these two regions. Comparison between the numbers of live yew and lost yew in different areas are shown in Table 2. We identify that, overall, 10% of previously recorded yew have now been lost, but these levels are more than double in the worst affected counties: Glamorgan, Yorkshire and Warwickshire. The highest numbers of lost Notable yew trees recorded are 23 in Somerset and 20 in Kent. While Scotland is shown to contain just 4% of the population, it contains the yew with the largest recorded girth at 17.06m (56 ft). In terms of habitat, a total of 1,855 individual trees (67% of the recorded population) are located in churchyards. Woodland and garden yew account for just 9% and 6% of the population, respectively. Churchyards also account for the highest number of all recorded lost yew, 223 (79%). In contrast, just three trees are recorded as lost from woodland. Discussion Exceptional yew While it is recognised that our data records only a small part of the total population of yew, it identifies a very high proportion of those trees considered most valuable in terms of conservation. Read (1999) defines veteran trees as those of interest biologically, culturally or aesthetically because of their age, size or condition, and suggests that oak specimens with a girth of more than 4.7m be considered veteran and valuable in terms of conservation. Our defined category of Veteran yew should be considered in similar terms, while those cate-
gories of Ancient and Exceptional yew increase exponentially in rarity and value. A further aspect to the importance of this largegirthed yew is age. Establishing the age of yew is complicated by the general hollowing characteristic of trees over 4.6m in girth (Mitchell, 1972). However, the use of partial increment cores and sections from both hollow trees and solid trunk churchyard yew in the SE region provides reasonable empirical evidence that one metre of girth equates to around one hundred years of age (Moir, in preparation). This helps confirm previous estimates that suggest that yew trees categorised here as Exceptional are likely to be near or over 1,000 years old, which further highlights the importance of these trees. The distribution of yew Churchyards contain 717 pecimens (73%) of the total 976 recorded yew with girth of 5m or more, highlighting this habitat as the most important for the preservation of large-girth yew. Exactly why yew is associated with churchyards remains unclear, but it has been suggested that the larger yew at such sites may be survivors from saint cells from the sixth to seventh centuries AD (Bevan-Jones, 2002). The small (3m x 4m) cells or hermitages of early saints (which may have been little more than a few stones, or wooden constructions) can leave little archaeological evidence or may be incorporated into later churches. Wales has no examples of natural woodland yew (except in a few areas of cliff (Bevan-Jones, 2002)); therefore the abundance of large yew is most likely explained by planting. It is also of interest that, assuming one metre of girth equates to around one hundred years of growth (Moir, in preparation), then the drop after the peak frequency of yew (Figure 2) coincides with the dissolu-
tion of the monasteries at the end of the medieval period (c.1539). Similar evidence for a relationship between churches and yew comes from a study using increment cores from the yew at the Dunsfold Parish church in Surrey (Moir, 2004). The study at Dunsfold concluded that the church and the yew were likely to be of the same age. Earlier studies on yew have also suggested a link between the planting dates of yew and their location in relation to a church (Chetan and Brueton, 1994). Losses of yew Sixty-seven percent of all recorded yew are located in churchyards. However, 717 of the 976 recorded Ancient yew (≼5 m) (73%), and 50 of the 55 (91%) Exceptional yews (with girth ≼9 m) are located in churchyards. This research highlights the churchyard habitat as a critical habitat for the conservation of large-girthed yew trees. Rather startlingly, 10% of large yew trees previously recorded in churchyards are shown to have disappeared; the majority over the last one hundred years. The loss of yew trees from churchyards is increasingly being recognised (Greenwood, 2013). It is worth noting, however, that yew trees in prominent positions such as churchyards and historic sites are more likely to have been recorded, so the totals may be biased towards churchyard yew loss, while the more easily missed woodland yew losses may be under-represented. However, on balance, the general inclusion of multiple large trees into a single record in this study means that the full extent of large-scale losses at a number of sites is likely to be under-represented. For example, at Sullington (Sussex) only one of six yews now remains, at Blaina (Monmouthshire) eleven substantial trees have all been removed, and at Strata Florida (Scotland) only two of what was once 39 yew remain (Bevan-Jones, 2002). It is
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possible that these losses are in part a response to the pressure on churchyard space for burials and buildings. While it was considered beyond the scope of this study to quantify the timings and reasons for losses, this information is often available, and analysis of these factors in the future is suggested to help identify simple strategies to help conserve yew. For instance, a total of 28 churchyard yews are recorded as lost due to storms, therefore it is hypothesised that preventing the removal of the lower branches may help mitigate the apparent susceptibility of these trees to wind damage. The importance of the churchyard habitat There are two general conservation strategies for slow-growing long-lived species that are rare and confined to small geographical areas: a) reinstituting the ecological processes important for the recruitment of new individuals (for example, removal of animal browsing pressure on seedlings), and b) protecting established individuals. From our data, hardly any large yews are recorded in Special Areas of Conservation of yew woodland, and just 9% of trees are located in woodland, demonstrating the limited importance of these habitats in the conservation of Britain’s largest-girthed yew. It can be argued that the wide regional coverage of large-girthed yew shown here should be viewed as important for the long-term viability of the yew population in this country, due to the critical role they may play in regeneration. Yew seeds are primarily dispersed by birds (Iszkulo and Boratynski, 2004), therefore individual yew allow spontaneous germination under canopies of other tree species some distance from them. In a study on the South Downs of the Hampshire/Sussex border, Tittensor (1980) found yew woods often along parish boundaries and suggests their likeliest ori-
gin is from parental seed trees that marked those boundaries. Largegirthed yew also form a widespread interlinked network that produce abundant pollen that can be borne long distances by the wind, helping to preserve the genetic variation required to maintain population viability. The regeneration of Britain’s younger yew woods and future yew wood is therefore likely to be interlinked with the health of the population of large individual yew. Future research Interestingly, in studies on the yew woods of the South Downs, Tittensor (1980) found 62% of yew on steep slopes, 90% on chalk and 80% of woods occurring in areas of high rainfall (>1000mm per year). The influence of factors such as rainfall, slope and substrate on the population of individual recorded trees is highlighted for future investigation. Also, despite Scotland’s comparatively small population, the few examples of large yew identified there may be critical in helping to establish whether yew is native to Scotland. The relationship between planting yew and churches may be significant and further research to explore the possible correlation between the establishment of churches and the girth of their associated yews is currently under way.
Conclusions 1 This study maps all known yew trees of 5m or more girth in England, Scotland and Wales and highlights that just 55 ‘Exceptional’ yew trees (those with a girth of 9m or more) survive. 2 Previously known areas with high proportions of large-girthed yew in Hampshire and Kent are shown to contain 17% of the population, while Powys has 12%. Previously unrecognised areas with high proportions are identified in Somerset, Gloucestershire, Shropshire and Herefordshire, which between them contain 19% of the population. 3 67% of large-girthed yew trees are recorded in churchyards, and recent losses suggest a need to better safeguard the exceptional trees that survive in this habitat. Acknowledgements This research was funded by TreeRing Services, UK. The Ancient Yew Group database is made accessible to the public as the Yew Gazetteer, thanks to the sponsorship of the Tree Register of the British Isles and the Conservation Foundation. We thank all those who submitted data to the Ancient Yew Group database. We are grateful to Lesley Trotter and an anonymous reviewer for comments that substantially helped improve this paper.
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Shell-wall thickness and breaking safety of mature trees By Frank Rinn
Abstract The acceptable level of trunk hollowness with regard to the breaking safety of trees has been debated for decades but remains unresolved for most tree experts because of contradictory statements, theories, and publications. However, research and observations clearly demonstrate that mature (large diameter) trees require much less remaining shell-wall thickness for reasonable stability, than younger trees still growing in height. Furthermore, stability of mature trees is surprisingly independent of wood material properties such as fiber strength. Keywords shell-wall thickness, one-third-rule, breaking safety, tree safety Introduction Storm events often lead to breakage of conifer trees in forest stands, even those with intact cross sections. Breakage, though, is probably more likely to occur if decay is present. (Fig. 1). On the other hand, old trees are known for having surprisingly thin shellwalls, often for many decades (Fig. 2), yet many survive even strong storm events — even trees that are quite tall or have large, wide-spreading crowns. These observations seem contradictory, but can be explained as subsequently shown. The uncertainty about potential stem breakage safety was one of the reasons for developing mobile testing methods to detect internal decay, and for measuring shell-wall thickness. In 1984, two retired German engineers (Kamm & Voss) tested a drilling device using a spring-driven scratch pin, and which recorded a 1:1-scaled profile of the thin needle’s penetration resistance on a wax paper strip within the machine. These profiles allowed for the detection of large voids in trees, but were found to be systematically wrong in the more intact portion of the stem because of resonance and damping effects of the spring-loaded recording mechanism. Thus, evaluations of utility poles, trees, and timber products based on such profiles were
also systematically wrong and unreliable. For example, decay was identified were the wood was just soft (by nature), but intact. Consequently, Kamm & Voss developed a resistance drill that recorded data electrically. With that improvement, they then tried to sell the corresponding systematically wrong in the more intact portion of the stem because of resonance and damping effects of the spring-loaded recording mechanism. Thus, evaluations of utility poles, trees, and timber products based on such profiles were also systematically wrong and unreliable. For example, decay was identified were the wood was just soft (by nature), but intact. Consequently, Kamm & Voss developed a resistance drill that recorded data electrically. With that improvement, they then tried to sell the corresponding patent application (Kamm & Voss 1985). A company interested in the intellectual property asked a German University whether the concept, based on measuring needlepenetration resistance, was practical. Starting in 1986, this idea became the patent application (Kamm & Voss 1985). A company interested in the intellectual property asked a German University whether the concept, based on measuring needlepenetration resistance, was practical. Starting in 1986, this idea became the subject of a physics graduate research thesis (Rinn 1988). This research resulted in further technical developments and finally, patent applications describing high-resolution machines and drilling needles (Rinn 1990, 1991). The results clearly showed that regulation of the machine, acquisition of measure-
Figure 1. In forest stands, internally decayed stems show a significantly higher breaking probability, but even completely intact cross sections may break.
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ment values and recording of the profiles must be done electronically to ensure a distinct (linear) correlation between the obtained profiles and wood density— the major wood material property (Rinn et.al. 1989 & 1996). Only those profiles obtained in this manner, enable the user to correctly interpret results and reliably evaluate wood condition (Rinn 1996). Thereafter, wood samples from all over the world were tested with these improved devices. It’s interesting to note that in stems of coconut palms (Fig. 3) it was found that approximately ⅓ of the trunk radius has a significantly higher density (and strength). Some years later, Mattheck and Breloer published statistical data (1994) claiming that breaking safety of tree trunks is significantly lowered if the remaining intact outer shell wall (t) is thinner than ⅓ the radius (R). This finding was interpreted as confirmation of a potential natural mechanical design because the mechanical load characteristics of coconut palms are similar to slender conifers in forest stands. Eventually, new analytical and computational methods suggested that tangential tension stresses as a consequence of bending or torsional loads may explain the increase of breaking failures of trees with a t/R< ⅓ (Ledermann 2003). This result was expected because torsional and shear strength of wood are comparatively low (Blass und Schmidt 1998). Years later, critics claimed that there is no scientific proof of the socalled ‘Mattheck’s ⅓ -rule’ (Gruber 2007, 2008), and thus, no valid reason to fell trees if t/R< ⅓. Consequently, practitioners and experts became increasingly unsure about which method or ‘rule’ to apply for safety evaluation of trees.
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Trunk and crown relations The mechanical bending load of upright tree trunks is mainly determined by wind load (Spatz & Bruechert 2000). Because wind speed tends to increase with height above ground, and drag is dependent on wind speed to the power of two, tree height is the dominating allometric wind-load factor. Consequently, after a tree has reached maximum height, wind load does not increase any more (White 1998), although old branches may locally
Figure 2. Large, old trees with very thin shell walls (t/R<1/5) often remain standing for decades despite the loss of much of their stem cross sections. face higher drag due to higher wood stiffness (Fratzl 2002). While the crown does not grow any more, girth usually continues to increase due to annual radial growth increments. That means the trunks of aging trees continuously gain load-carrying capacity, while the load remains fairly constant. Consequently, the increasing girth of aging trees automatically leads to a steady increase in the trunk breakage safety factor (= load-carrying capacity / load). And this leads to the question: How hollow can a mature tree become, before the risk of stem breakage is unacceptable? Numerical estimation (based on Gere and Timoshenko 1997) Mechanical stress (S) in a cross section is usually defined as the acting force (F) divided by the area (A): S=F/A If a bending moment (M) is applied, stress can be calculated from S=M/W W characterizes the section modulus that is usually determined by an integral over the cross sectional area. For cylinders of diameter (D) and a central void of diameter (d), W can be calculated in a simple form: W = π * (D4 – d4)/(32*D) Strain in the material is usually defined by changes in length (ΔL) divided by the observed distance (L): ε = ΔL / L At the same time, strain is a consequence of external loading and strongly determined by the modulus of elasticity (E): ε = ΔL / L = S / E This helps to explain the influence of material strength (= maximum applicable stress = Smax) on the maximum bending load that can be applied without causing damage: Mmax = W * S max In an intact cylindrical cross section (d=0), the dependence of the load carrying capacity on diameter and material strength is obvious: Mmax ~ D³ S max Therefore, a doubling of the material strength value of the wood (Smax) in the whole cross-section leads to a double maximum applicable bending load (Mmax). A doubling of trunk diameter, however,
leads to an eightfold increase in maximum applica- Figure 3. A resistance ble bending load: drilling profile of a (2*D)³ = 8*D³ coconut palm stem Compared to the impact of diameter increase on to- disk showing linear tal load carrying capacity, higher material strength correlation to wood within a newly formed tree ring is only of marginal density, and that relevance. The influence of radial growth of a stem approximately ⅓ of cross section in terms of dimension is thus, far more the outer radius has important than changes in material properties. significantly higher Therefore, we can characterize the load-carrying cawood density. pacity of cylindrical cross sections in first order by its diameter. will be D2 = 66cm. If this trunk cross section then (at y = 20) would have a central void of d2 = 47cm, Diameter growth with age it would have the same load-carrying capacity as the As already shown by Bräker (1981), ring width of completely intact cross section at y=0 (Fig. 4) That mature trees usually stabilizes as a nearly constant means, if we assume the tree at y=0 is “absolutely value. If we assume that ring width, after the tree has safe in bending” (because it is completely intact), reached maximum crown height (time point y=0), we have to grant the same level of safety 20 years is a percentage (p) of the diameter at this time (D1), later to this tree with a diameter of 66cm if there is we can estimate later diameters (D2), years (y) after a central void leading to a t/R ratio less then ⅓: t2/ D1 was reached: R2 = 9.5/33 ≈ 0.29, because these two cross-sections D2 = (1+ y * p) * D1 provide the same load-carrying capacity and thus, similar breaking safety. The corresponding section modulus can then be written as: If we assume a cylindrical trunk (D1= 60cm) has a central void of d1= 40 at y=0 (that means a t/R= ⅓), after y = 20 years and p = 0.5%, D2 would be 66cm. If this trunk then has a central void of d2= 52 (=>t2/ R2≈ 1/5), it would provide the same load carrying capacity as with a t1/R1= ⅓ at y=0 (Fig 5). What Now we can ask the most important question: at this means in terms of bending safety for such trees what point (level of hollowness) does a large old tree is that: a t/R= 1/5 at y = 20 is equivalent to a t/R= ⅓ become unstable? For easier evaluation we transabout 20 years earlier (y=0). If we believe a t/R= ⅓ is form diameter values into shell-wall thickness (t) a measure representing sufficient ‘stability’ of a tree and stem radius (R): at y=0, then we have to accept, that 20 years later, t/R = 1 – d/D a t/R= 1/5 represents the same amount of ‘stability’ Once we set W2! = W1 , we can calculate t/R-ratios and relative safety. equivalent to the ones at y=0: Consequently, the critical t/R ratio is not a constant value, but strongly depends on trunk diameter and thus age (and crown size), as soon as the height does not increase any more.
With this formula we can determine the t2/R2-ratio at any given point in time of maturity (y>0), which is equivalent to a certain t1/R1-value at y=0. Practical application If we assume an intact (d1= 0) tree trunk has a diameter of D1= 60cm (about 24 inches) at the time when its crown reaches its maximum height (y=0), and then an annual ring width of 3mm (p = 0.5% of D1), the diameter of the trunk after y = 20 years
Consequences and limits Especially in the urban landscape, risk of tree failures, resulting in injury to people or property damage, resulting from tree failures, increases with age. Therefore, most trees that require a thorough assessment are more or less mature. Consequently, the approach described here is relevant for the majority of urban tree inspections, especially for level 2 and 3 as defined and explained by the ISA tree risk assessment qualification (TRAQ). The comparative shell-wall safety estimation method as described above, shows that the so-called ‘⅓-
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Figure 4. (Left) These two cross-sections (sketch to scale) provide the same load-carrying capacity and thus the same breaking safety provided the same wind load is applied. Figure 5. (Right) The left cross section of a decayed tree stem at year=0 provides a t/R≈⅓. The image on the far right shows the same cross section after 20 years of annual increment growth and further decay progression with a t/R≈1/5. Assuming the same wind load, these two cross sections (sketch made to scale) provide approximately the same load-carrying capacity, therefore, if an expert evaluates the left cross section as acceptable (‘safe enough’) at the time of inspection (y=0), the same grade of safety has to be granted to the tree 20 years later despite a thinner shell wall. rule’ may be correct for a certain kind and age class of trunks, but has no relevance for mature trees, and should not be used to justify felling or even extensive crown reduction to mitigate risk for such trees. In mature trees, a t/R= ⅓ is not even the starting point for being concerned about breaking safety, because, as shown above, in terms of breaking safety, a t/R= 1/5 or even less can be equivalent to a t/R= ⅓ at the time the tree reached maximum crown height. This explains why large, old, hollow trees with very thin shell walls often stand for decades, despite large crowns and exposure to strong wind.
occur, and because longitudinal dimension of wood deterioration or other structural damages become more important (Niklas and Spatz 2012; 2013). This aspect shall be explained in future publications.
In addition, in terms of loss of load-carrying capacity (LCC), the location of decay (centered or uncentered) within the cross section, as well as cross-sectional shape, are more important than just the size of deteriorated parts (Rinn 2011). Comparatively small areas of decay in the outer sapwood of the stem, or on the upper side of a horizontal branch can lead to significantly greater losses of LCC and thus, have a When we assume the ⅓-rule as being correct in degreater impact on safety than large centrally located scribing the point where the probability of breaking voids. Consequently, for assessing the stem breaking failures starts increasing significantly for centralsafety of mature trees, it is not enough to determine ly decayed, thin, and tall, slender forest trees (and shell wall thickness by, for example, resistance drillcoconut palms), we have to accept that this starting at just one point, or measuring fiber strain with ing point for concern shifts down to Figure 6. Two examples of decayed trunk cross sections of mature urban thinner shell walls once maximum trees (left: Ulmus, right: Tilia). Decay columns are often asymmetric beheight growth is reached, because cause they develop from trunk wounds or damaged roots. In addition, tree /diameter continues to increase. many mature urban trees do not have cylindrical cross sections. Thus, simIn the second example described ple measurements of shellwall-to-radius-ratios, or the local assessment of above, the starting point for concern strain by pull-tests can hardly be applied correctly for evaluating breaking would be a t/R= 1/5 (assuming that safety. In such situations, tomographic assessments are required for obtaina t/R= ⅓ is the starting point of coning more precise results and more reliable evaluations. cern for younger trees as described above).
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However, it has to be taken into account that this approach as presented here is valid only as long as t/R>1/10, approximately. Below this ‘limit’, and if big, open cavities are present, more complex approaches and estimations have to be applied, because other failure modes may
only one elongation sensor during one pull-test. Both results are valid only for the point of measurement and cannot be extrapolated to the whole trunk. Results can be quite different in other areas of the same cross section, and even more so, up and down the trunk. If devices that can be calibrated are properly applied, both measurement methods (resistance drilling and pull test strain-assessment) can deliver valuable information, and significantly enhance tree risk evaluation compared to visual grading alone. But it has to be taken into account that each result is only valid for the point of measurement. In this sense, tomographic approaches deliver more information, but still have to be understood and interpreted correctly. (Fig. 6)
Jon Turnbull during his ITCC Masterâ&#x20AC;&#x2122;s Climb
Without knowing the weakest point of the tree trunk under external loading, every localized measurement is just an approximation and cannot describe the mechanical behavior of the whole cross section, trunk or even tree. This limitation is valid for all technical methods and devices in a specific certain way, and has to be clearly understood, explained and communicated by the experts. The shell-wall-to-radius-ratio (t/R) required for sufficient breaking safety is not a constant value over time, but decreases as trees mature and increase in girth. Understanding and applying this aspect of natural tree architecture while inspecting and evaluating mature urban trees can prevent unnecessary felling or crown reduction as compared to current standards - for the good of nature, people, and municipal budgets. In this manner, trees can be retained longer to provide social and environmental benefits that enhance quality of life in urban landscapes, without endangering people and their property. Frank Rinn Heidelberg/Germany
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Professor and Researcher from United Kingdom Honored with Education Award from the International Society of Arboriculture.
of the organization. The winners are selected by a diverse group of experts in arboriculture. More than 20,000 members make up ISA’s organization worldwide.
CHAMPAIGN, Ill., U.S. (August 2013) – Dr. Mark Johnston, a professor and research fellow in arboriculture and urban forestry at Myerscough College in Lancashire, United Kingdom, is this year’s recipient of the International Society of Arboriculture’s (ISA) prestigious Alex L. Shigo Award for Excellence in Arboricultural Education.
The International Society of Arboriculture (ISA), headquartered in Champaign, Ill., is a nonprofit organization supporting tree care research and education around the world. To promote the importance of arboriculture, ISA manages the consumer education web site, www.treesaregood.org, which fulfills the association’s mission to help educate the public about the importance and value of proper tree care. Also, as part of ISA’s dedication to the care and preservation of shade and ornamental trees, it offers the only internationally-recognized certification program in the industry. For more information on ISA and Certified Arborists, visit www.isa-arbor.com.
The Alex L. Shigo Award honors ISA members for enhancing the quality and professionalism of arboriculture through education. ISA President Terrence Flanagan honored Dr. Johnston at a ceremony on Sunday, August 4th in Toronto, as part of the ISA Annual Conference and Trade Show, August 3rd–7th, 2013. “Dr. Johnston has worked as a contractor, consultant, tree officer, and college professor to connect people with trees in schools and communities throughout Britain and Ireland,” says Flanagan. “He has helped hundreds of young men and women complete their degrees in arboriculture in addition to his development of online courses to make higher-learning available to students everywhere.” Responsible for the Forest of London project, Dr. Johnston led Britain’s first city-wide urban forest initiative and inspired other major urban forest projects across the UK. His Trees in Towns II survey for the government on urban trees in England is considered an influential policy and practice guide. He developed and led Myerscough College’s Master of Science program in Arboriculture and Urban
ABOUT ISA
Forestry, the only post-graduate course of its kind in Europe. Dr. Shigo, a renowned plant pathologist, was known throughout the industry for his studies on tree decay, which led to major changes in arboriculture. “I met Alex Shigo in 1980 at a joint ISA-AA conference in England and was fortunate to sit through his impromptu workshop,” says Dr. Johnston. “When I became a full-time lecturer, Dr. Shigo’s books, videos, and research papers were required learning materials for my students. This great man has not only had an influence on me, but also on the thousands of students I’ve taught.” Johnston is one of eleven distinguished professionals who make up the circle of winners for ISA’s Awards of Distinction, sponsored by Bartlett Tree Experts. Robert Bartlett Jr., Chairman and CEO of Bartlett Tree Experts explains, “Bartlett is proud to partner with ISA in support of the 2013 Awards of Distinction. These individuals are truly ‘champions of tree care.’ We applaud all of the honorees for their tireless effort in research, teaching, mentoring their peers, and dedication to the best daily practices of arboriculture.” ISA has been honoring members and industry professionals with the Awards of Distinction since 1963. Nine categories recognize candidates in such areas as research, publishing, education, and advancing the cause
ABOUT BARTLETT TREE EXPERTS The F.A. Bartlett Tree Expert Company was founded in 1907 by Francis A. Bartlett and is the world’s leading scientific tree and shrub care company. The organization’s current chairman, Robert A. Bartlett Jr., represents the third generation of Bartlett family management. Bartlett has locations in 27 U.S. states, Canada, Ireland, and Great Britain. Services include pruning, insect and disease management, fertilization and soil care, cabling and bracing, tree lightning protection systems, and tree and stump removal. Its corporate offices are located in Stamford, Connecticut. To find out more, visit the company’s web site at www.bartlett.com or call 1-877-BARTLETT (2278538).
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Connecting People in the U.K. with Trees
Dr. Mark Johnston — Alex L. Shigo Award for Excellence in Arboricultural Education Professor, Research Fellow, Arboriculture and Urban Forestry Myerscough College It was the early 1970s and Mark major government study,” says Preston, United Kingdom Johnston was working on timber felling when he had a chainsaw accident. It was this mishap that got him thinking about the future.
“Do I really want to be doing this when I am 40?” Johnston recalls. The job was becoming increasingly demanding for him as he grew older each year. Johnston, who had left school early with no real qualifications, began to realize that he needed additional education to advance in a career. So, he made a decision. “I signed up for a basic course in tree surgery that didn’t require any formal qualifications—only that I have experience,” he remembers. “When I passed that course, I was qualified to take another higher level arboriculture course and so I continued. I learned a valuable lesson—one I have always passed on to my students: get qualified and then anything is possible.” From the time Johnston began his studies in 1975, he developed a love for arboriculture and kept studying while working in the field. He eventually earned his Royal Forestry Society (RFS) diploma working as a London tree officer and then obtained his Ph.D. in urban forestry from the University of Ulster. “Once I was involved in arboriculture, I never looked back,” Dr. Johnston recalls. “For me, urban forestry was the perfect combination—a concern for people and a concern for trees.”
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Dr. Johnston began teaching arboriculture at various colleges in England and also as a visiting lecturer at the Chinese University in Hong Kong. Today, many of his students in Hong Kong now hold high positions in parks management and tree care. Since
his arrival at Myerscough College in Lancashire, England, Dr. Johnston has helped hundreds of young men and women complete their degrees in arboriculture. He is also responsible for developing and leading the college’s Master of Science in arboriculture and assisted in the development of online courses to make higher-learning available to students everywhere. “The master’s course at Myerscough is unique as far as Europe is concerned,” explains Dr. Johnston. “It’s the only post-graduate qualification of its kind here. We attract graduates in related subjects from many countries overseas. Our range of online courses is also unique internationally drawing interest from all over the world.” In addition to his teaching, Dr. Johnston is a dedicated researcher, involved in tree care projects and the study of urban forests. “The ‘Forest of London’ project was Britain’s first city-wide urban forestry initiative, which had far-reaching impact in both Britain and Ireland,” Dr. Johnston explains. “I launched it in 1987 and led the program, which emphasized partnership working, community education, and involvement. The greenprint from this project was later adapted to other cities, including Dublin, Republic of Ireland; Cardiff, Wales; Glasgow, Scotland; and Belfast, Northern Ireland.” Dr. Johnston has published a number of papers related to his studies. In 2008, he wrote the influential “Trees in Towns II: A New Survey of Urban Trees in England and Their Condition and Management.” “I was the lead researcher on this
Dr. Johnston. “The publication established a planned, systematic and integrated approach to managing urban forests in Britain. The research is expected to influence policy and practice for many years to come.”
Dr. Johnston has worked in arboriculture education for 18 years and is honored to have his work recognized by ISA. But it should also be noted that Queen Elizabeth II has commended Dr. Johnston for his contributions to arboriculture and urban forestry. Dr. Johnston is a Member of the Most Excellent Order of the British Empire. “I was particularly pleased that the citation mentioned my cross-community work in the Forest of Belfast project,” Dr. Johnston replies, “where I tried to use trees and tree planting as a uniting tool between divided communities. Although I was born in London of Scottish descent and have worked in Britain for most of my career, I have lived in Belfast for the past 20 years. My wife is Irish.” For nearly 40 years, Dr. Johnston has dedicated himself to connecting people with trees all across Britain and Ireland, working as a contractor, consultant, a tree officer, and a professor. The lesson he learned early on to discover as much as possible about the trees around us is one he wishes to pass on to future generations. “I would like the respective governments to ensure that all young schoolchildren in Britain and Ireland learn about tree planting and basic tree care as part of their regular education. I think that could make a huge difference in their attitudes and behavior toward trees and the environment once they become adults.” –Dr. Mark Johnston
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Ride for Research .... ... get on your bike ... plant trees with school children ... raise money for tree research The ride is suitable for all abilities and open to anyone working in the forestry and arboricultural industries. There is a minimum requirement to raise ÂŁ150 of sponsorship. Find out more at:
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In search of the perfect report Part II by Jeremy Barrell
In Part l of this article written to accompany his seminar ‘Expert’s Question Time’ co-hosted with Dr. David Lonsdale at Kew Gardens on Tuesday 25th June, Jeremy shared his views on the importance of experience and the process of starting a new commission. In part ll, he looks at the elements that need to be completed before he begins to write the actual report. Collecting and managing relevant information The reality of many tree failure cases is that they do not progress to formal legal proceedings until some considerable time after the event, which in some instances can run to a number of years. Almost invariably, with such a lapse of time, the tree or tree-part that failed is long lost and there is nothing left on site but a space where the tree once stood. Under such circumstances, ‘Why bother with a site visit?’ and ‘Is it really necessary?’ are common questions asked by instructing lawyers, keen on keeping costs to a minimum. The response is that a site visit is absolutely essential and I rarely take on cases where
one is not agreed. When a tree fails, the immediate surroundings and specific circumstances are always a material consideration in assessing whether the event was reasonably foreseeable, and the only way to reliably get that context is to visit. In addition to the health and structural issues of the actual tree, matters such as exposure to wind, recent loss of shelter, recent root disturbance, failure patterns in nearby trees and ground conditions, can all have a bearing on why a failure occurred. The default for me is always to visit, even on the lowest value cases or if the tree has gone, and it would be very unusual not to do so. It is easy to get carried away with being an expert and focus on the detail at the expense of the wider context, and detailed investigations of tree parts that failed is a common area for making that mistake. The reality-check is that the courts rarely seem to be interested in what sort of fungus caused the failure, or the ratio of sound wood to decayed wood in a cross-section, or the retrospective application of this or that method of assessing the level of
risk. What seems to be much more important is whether the cause of failure would have been discoverable before the event, and the starting point for that aspect of management, as set out in the HSE SIM, is a “quick visual check”. What could be seen by looking from ground level is what matters, and although detail of what could not be seen may be of passing interest, it is unlikely to influence any judgment. The only exception to that would be if there were discoverable visual indications of a problem that would have triggered more detailed investigations, in which case it would be prudent to establish what such investigations would have been likely to discover. However, in the bulk of situations, my experience is that there is no need for anything more than recording dimensions and features that would have been visible from a ground based inspection. More often than not, the only evidence of tree condition and the detail of the failure is in the form of photographs, and their interpretation can often dictate the course of a case. Indeed, two of my current cases have featured on TV
reports of accidents, so images can extend to high quality video footage as well. In the absence of the actual tree or part that failed, images have the potential to be extremely helpful for exploring detail well after the actual event. Considering how pivotal images can be, it is surprising how often the tree expert gets incomplete sets of poor quality photocopies, and yet it is almost normal rather than the exception. The experienced expert will always ask for good quality copies and always remind the instructing lawyers to request in writing from the other side that all images of the event are disclosed. A more recent evolution of using images to assist expert analysis is to visit the location on Google, with Streetview often providing quite detailed views of roadside trees before the failure. Legal proceedings always have a strong focus on documents, sometimes running into thousands of pages, and managing such vast amounts of paper is a headache. This is often compounded by them being sent in dribs and drabs, without proper referencing, pages sometime duplicated or missing, and even the odd word being changed without any indication. Lawyers tend to leave all this to their administrative support, which is probably the root of
the problem, because to get document management right takes a lot of time and brainpower. It may be mundane to read every page and makes sure it is stored with the date received and the number of pages meticulously catalogued, but being organised to this level is a core skill of effective experts. Invariably, the lawyers donâ&#x20AC;&#x2122;t do it, so you have to, and experts who pay very careful attention to this detail will be the ones who find that critical sentence or even a single word that can make the difference between winning and losing. Writing the report: Phase l The ultimate purpose of a legal report is to assist the court in understanding matters that are beyond its expertise, and it must be written for the court, not the entity paying for the service. It is a clear duty of the report-writer to discharge that task with competence, due care, integrity, independence and impartiality, and to present an objective and balanced position to assist the court in making its decision on the matter in dispute. These are onerous constraints, but this is the framework that all legal reports must be constructed within. Indeed, all experts must be ever-mindful of this rigid duty in the process of evolving opinions and then presenting them as written
reports. Throughout the writing phase, these requirements should be at the forefront of your thinking, setting the mental framework for every aspect of the exercise. Legal cases are invariably complicated and that takes clear thinking to understand, assess and analyse. No doubt there are many ways to achieve this, and the approach is bound to vary with each individual, but here are a few ideas that seem to have assisted me in improving my writing. As preparation, I always start by scanning the documents to give me a quick overview, which seems to help establish a rough framework of the issues very early on. I highlight matters that seem important, usually write short notes on the page near them and then tab the page so that I can easily find it again. All this is before the site visit, but I still take the full papers when visiting in case something crops up that I missed in the scan. During this period, I start to think about and locate technical references that I think may be useful in clarifying the issues that begin to emerge. I very rarely rely on books and publications, but often they provide technical support for an experienced-based opinion, so it is necessary to have copies and refer to them.
TRAQ Review
By Ian McDermott Been there, done that! Congratulations to all those who recently completed the inaugural Tree Risk Assessment Qualification at Capel Manor college on the 14th to the 16th October. Pictured at the bottom during one of the written assessment from left to right are: Arron Sanderson, Alvan Kingston, Matt Stuart, Ian Barnes, Steve Maros, Colin Quinn, Hal Appleyard, Dan Yeomans, Tim Wilcox, Russell Ball and Craig Johnson. The food was good too (in the foreground and our very grateful thanks go to the ever helpful and friendly staff at the college. Of course, the bonus for the TRAQ is that Capel has some great trees, and below the students are pictured looking at one of the large Oaks in the grounds in preparation for the field assessment portion of the exam. If you are interested in taking this course then please contact the chapter office to register your interest as we are now taking names for the next one. Look forward to seeing you there.
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