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  1. The Arboricultural Association

    A new approach to protecting trees during construction

    Barrell Tree Consultancy has been working to promote the importance of existing trees in planning for more than two decades, but what practical wisdom has emerged from more than 7,000 completed projects? In this article, Jeremy Barrell explores the subtleties of effective tree protection on construction sites, and shares a new approach showing promising signs of success. It seems that a cocktail of back-to-basics and images packaged as concise Site Guidance Notes is improving how site operatives deal with trees, and delivering a much needed environmental windfall in the planning process. The political aspiration of ‘net environmental gain’ compared to the current reality The government’s flagship environment policy draft, A Green Future: Our 25 Year Plan to Improve the Environment, introduces the concept of ‘natural capital accounting’ into mainstream political thinking. Hard on its heels, the draft National Planning Policy Framework (NPPF) repackages the concept as ‘net environmental gain’, but it has a similar meaning. Either way, the political momentum is with the wisdom of being careful with existing environmental assets, which is particularly relevant to urban trees because they are already in place delivering multiple benefits right where they are needed most, where people live and work. The aspiration is admirable, but the current reality on the ground is somewhat different. Our experience from working on construction sites for two decades is that there is a chasm between the tree retention promised at the design/planning stage and what is delivered on completion. Our perception is that good trees are being unnecessarily lost during development, and that is significantly contributing to a national trend of decreasing urban canopy cover. A worrying observation, even more confounding because the technical expertise to protect trees is well-developed, there is a planning imperative to do so, and it is relatively inexpensive to achieve. Barriers to successful tree retention In our quest to find a solution, we identified several practical and procedural barriers to successful tree retention: Communication breakdown: There is often poor communication between the planning and implementation stages of the development process, so it is common for the site operatives to be unaware of tree protection agreed with planners. British Standard (BS) guidance: The BS guidance is copyrighted, which prevents its detail being easily reproduced to explain specific operations. Weak planning conditions: Poorly informed/inexperienced planners often write weak planning conditions, and so agreed tree protection cannot be enforced as intended. Formal reports: Although detailed reports are an essential part of describing a development proposal in the design and planning stage, once consent is issued, those reports are rarely found or used on site, i.e. site operatives meant to implement tree protection do not have easy access to information on how to do it. Report aversion: People on site are not engaged by complex or lengthy reports, which results in key personnel not understanding how to properly protect retained trees. Ineffective enforcement: Local planning authorities (LPAs) often struggle to enforce detailed tree protection requirements that are not clearly explained in the planning application documents. On the bright side, we find that plans are a universally understood medium on site and their use is routine, so important information on plans has a better chance of being used than if it is buried in a report. Evolution of the Site Guidance Note (SGN) concept To make a real difference to tree survival, we wanted to develop a solution to bridge the procedural gap between planning and implementation, i.e. assist the operatives doing the building to understand the tree protection proposals and how to execute them on site. Our early efforts focused around including the detail of site operations within our impact appraisal reports submitted with planning applications, but this resulted in lengthy documents making it difficult to pinpoint specific information. Although this approach contained all the technical information, it drew regular criticism from tree officers as being too complex, generic, and not site specific. Our subsequent evolution illustrated the technical content with photographs of real examples from our thousands of projects, which was more effective at explaining, but still resulted in long reports, so was only partially successful. The report size issue was solved by the advent of improved internet storage of and access to information. We took our lead from the government approach to storing generic guidance for planning online: if that was acceptable for government administration, then why not for tree protection as well? Through this lengthy process of trial and error, the design priorities began to emerge to shape the concept of the SGN. Reports could be kept short and site specific by extracting and storing generic information online. That information needed to explain the principles of each individual tree protection operation in a way that made it easy for site operatives to understand and access. There needed to be a summary of the technical support references to add the necessary depth of detail and credibility. Photographs of tree protection operations were preferred to text explanations. Finally, the overview and detail of how to do each tree protection operation should be quickly and easily accessible through the tree protection plan. That was the design process, and this is what we came up with: twelve individual SGNs (Figure 1) covering the commonest tree protection issues, ranging from supervision, to fencing, to excavating in root protection areas. Each SGN starts with a concise bullet point summary of key information that site operatives should know, followed by images showing how it can be done, and concludes with a summary (not verbatim quotes) of the technical guidance. Each SGN can be downloaded free (www.barrelltreecare.co.uk/resources/technical-guidance/) and accessed directly on site using mobile devices to scan the QR Codes (Figure 2) on the tree protection plan. Using sGns Anyone can access and use each SGN free, but the source must be acknowledged, and their format/content must not be altered. Their multiple benefits include: LPAs can link online to SGNs to publicise planning expectations. Consultants can reference SGNs in their planning reports, either linking to the online source, or downloading them and inserting them directly into the report. Developers can use SGNs to specify tree protection for pricing and implementation. LPA planning officers can directly reference SGNs in planning conditions as a source of credible detail. LPA tree officers can use SGNs on site to explain tree protection expectations to developers. Site operatives can download SGNs to mobile devices on site as a quick reference when working near trees. When it all goes wrong, LPA enforcement officers can reference SGNs as clear examples of what was expected. In short, SGNs provide a common standard for reasonable tree protection expectations during development. Due to our sophisticated planning system, the UK leads the world in specifying and implementing tree protection on development sites. No other country has produced anything as comprehensive as these SGNs and we are currently discussing their international roll-out, with interest from New Zealand, Australia, Canada, and Sweden. And the final question: where is the payback to us for the significant intellectual capital invested in designing and delivering the SGNs? In practical terms our business is based on a reputation built over decades for innovation and efficiency, and our SGNs promote those characteristics. Although we are giving away great ideas, we are gaining credibility as architects of invention, and we place a high value on that. Professionally, we see business is changing fast, with consumer decisions increasingly driven by high ethical standards; it’s a risk, but we chose sharing over secrecy, and only time will tell if that was a wise choice! Article by Jeremy Barrell, taken from issue 181 of the ARB Magazine
  2. The Arboricultural Association

    A new approach to protecting trees during construction

    Barrell Tree Consultancy has been working to promote the importance of existing trees in planning for more than two decades, but what practical wisdom has emerged from more than 7,000 completed projects? In this article, Jeremy Barrell explores the subtleties of effective tree protection on construction sites, and shares a new approach showing promising signs of success. It seems that a cocktail of back-to-basics and images packaged as concise Site Guidance Notes is improving how site operatives deal with trees, and delivering a much needed environmental windfall in the planning process. The political aspiration of ‘net environmental gain’ compared to the current reality The government’s flagship environment policy draft, A Green Future: Our 25 Year Plan to Improve the Environment, introduces the concept of ‘natural capital accounting’ into mainstream political thinking. Hard on its heels, the draft National Planning Policy Framework (NPPF) repackages the concept as ‘net environmental gain’, but it has a similar meaning. Either way, the political momentum is with the wisdom of being careful with existing environmental assets, which is particularly relevant to urban trees because they are already in place delivering multiple benefits right where they are needed most, where people live and work. The aspiration is admirable, but the current reality on the ground is somewhat different. Our experience from working on construction sites for two decades is that there is a chasm between the tree retention promised at the design/planning stage and what is delivered on completion. Our perception is that good trees are being unnecessarily lost during development, and that is significantly contributing to a national trend of decreasing urban canopy cover. A worrying observation, even more confounding because the technical expertise to protect trees is well-developed, there is a planning imperative to do so, and it is relatively inexpensive to achieve. Barriers to successful tree retention In our quest to find a solution, we identified several practical and procedural barriers to successful tree retention: Communication breakdown: There is often poor communication between the planning and implementation stages of the development process, so it is common for the site operatives to be unaware of tree protection agreed with planners. British Standard (BS) guidance: The BS guidance is copyrighted, which prevents its detail being easily reproduced to explain specific operations. Weak planning conditions: Poorly informed/inexperienced planners often write weak planning conditions, and so agreed tree protection cannot be enforced as intended. Formal reports: Although detailed reports are an essential part of describing a development proposal in the design and planning stage, once consent is issued, those reports are rarely found or used on site, i.e. site operatives meant to implement tree protection do not have easy access to information on how to do it. Report aversion: People on site are not engaged by complex or lengthy reports, which results in key personnel not understanding how to properly protect retained trees. Ineffective enforcement: Local planning authorities (LPAs) often struggle to enforce detailed tree protection requirements that are not clearly explained in the planning application documents. On the bright side, we find that plans are a universally understood medium on site and their use is routine, so important information on plans has a better chance of being used than if it is buried in a report. Evolution of the Site Guidance Note (SGN) concept To make a real difference to tree survival, we wanted to develop a solution to bridge the procedural gap between planning and implementation, i.e. assist the operatives doing the building to understand the tree protection proposals and how to execute them on site. Our early efforts focused around including the detail of site operations within our impact appraisal reports submitted with planning applications, but this resulted in lengthy documents making it difficult to pinpoint specific information. Although this approach contained all the technical information, it drew regular criticism from tree officers as being too complex, generic, and not site specific. Our subsequent evolution illustrated the technical content with photographs of real examples from our thousands of projects, which was more effective at explaining, but still resulted in long reports, so was only partially successful. The report size issue was solved by the advent of improved internet storage of and access to information. We took our lead from the government approach to storing generic guidance for planning online: if that was acceptable for government administration, then why not for tree protection as well? Through this lengthy process of trial and error, the design priorities began to emerge to shape the concept of the SGN. Reports could be kept short and site specific by extracting and storing generic information online. That information needed to explain the principles of each individual tree protection operation in a way that made it easy for site operatives to understand and access. There needed to be a summary of the technical support references to add the necessary depth of detail and credibility. Photographs of tree protection operations were preferred to text explanations. Finally, the overview and detail of how to do each tree protection operation should be quickly and easily accessible through the tree protection plan. That was the design process, and this is what we came up with: twelve individual SGNs (Figure 1) covering the commonest tree protection issues, ranging from supervision, to fencing, to excavating in root protection areas. Each SGN starts with a concise bullet point summary of key information that site operatives should know, followed by images showing how it can be done, and concludes with a summary (not verbatim quotes) of the technical guidance. Each SGN can be downloaded free (www.barrelltreecare.co.uk/resources/technical-guidance/) and accessed directly on site using mobile devices to scan the QR Codes (Figure 2) on the tree protection plan. Using sGns Anyone can access and use each SGN free, but the source must be acknowledged, and their format/content must not be altered. Their multiple benefits include: LPAs can link online to SGNs to publicise planning expectations. Consultants can reference SGNs in their planning reports, either linking to the online source, or downloading them and inserting them directly into the report. Developers can use SGNs to specify tree protection for pricing and implementation. LPA planning officers can directly reference SGNs in planning conditions as a source of credible detail. LPA tree officers can use SGNs on site to explain tree protection expectations to developers. Site operatives can download SGNs to mobile devices on site as a quick reference when working near trees. When it all goes wrong, LPA enforcement officers can reference SGNs as clear examples of what was expected. In short, SGNs provide a common standard for reasonable tree protection expectations during development. Due to our sophisticated planning system, the UK leads the world in specifying and implementing tree protection on development sites. No other country has produced anything as comprehensive as these SGNs and we are currently discussing their international roll-out, with interest from New Zealand, Australia, Canada, and Sweden. And the final question: where is the payback to us for the significant intellectual capital invested in designing and delivering the SGNs? In practical terms our business is based on a reputation built over decades for innovation and efficiency, and our SGNs promote those characteristics. Although we are giving away great ideas, we are gaining credibility as architects of invention, and we place a high value on that. Professionally, we see business is changing fast, with consumer decisions increasingly driven by high ethical standards; it’s a risk, but we chose sharing over secrecy, and only time will tell if that was a wise choice! Article by Jeremy Barrell, taken from issue 181 of the ARB Magazine View full article
  3. The Arboricultural Association

    Root Protection for Veteran Trees

    A common conflict between development and veteran trees centres on the protection of the rooting environment. Difficulties exist due to the subterranean nature of this important part of the tree, concealing it from view. The Ancient Tree Forum and the Woodland Trust have long drawn attention to this often overlooked part of the tree, emphasising the importance of healthy soil, mycorrhizae and roots and the need for appropriate management of the land around veteran trees. In November, the Forestry Commission and Natural England updated their standing advice, Ancient woodland and veteran trees: protecting them from development. This document sets out the principles planning authorities should consider for developments affecting ancient woodland and veteran trees. The standing advice picks up from the National Planning Policy Framework with regards to the importance of veteran trees and the need for their protection. Together these documents state that planning permission should be refused if proposals involve the loss or deterioration of veteran trees, unless the need for, and benefit of, development in that location clearly outweigh the loss (see the note at the end of this article for more info). The loss of a veteran tree is clear cut and easily defined; in such circumstances local planning authorities would weigh up the loss against the need for and benefit of development when determining an application. However, the deterioration of veteran trees is perhaps less black and white. The standing advice requires developers to identify aged and veteran trees as part of tree surveys and to show different root protection areas on plans. The Ancient Tree Forum and the Woodland Trust consider that all ancient trees and mature veteran trees should be recorded in Category A3 in accordance with BS5837:2012. The standing advice also recommends a larger root protection area for veteran trees, ‘at least 15 times larger than the diameter of a veteran tree’. Previous guidance – BS5837:2012 – recommends the minimum root protection area to be a 12 times larger with a cap at 707m2 (15m radius). However, do root protection areas based on an arbitrary calculation enable an informed decision to be made regarding the retention of veteran trees without ‘deterioration’? TreeRadar at the ARB Show In 2017 the Ancient Tree Forum attended the ARB Show with the aim of encouraging arborists to think about the rooting environment around veteran trees. A number of talks and demonstrations were held at the Ancient Tree Forum tent, which was situated adjacent to two veteran oak trees. TreeRadar in action Sharon Hosegood, Ian Lee and Noel Durdant-Hollamby from Sharon Hosegood Associates Ltd joined the Ancient Tree Forum for the weekend. Sharon and Co. brought with them their TreeRadar. This piece of equipment is able to record live tree roots, in excess of 20mm diameter, down to a depth of 3m, enabling the root system of a tree to be mapped without excavation. The aim for the weekend was to investigate the extent of the root system of one of the veteran trees and share the findings with attendees of the show. In advance of the show Sharon and Ian set about scanning the land around the tree to produce a map of the tree’s roots. In addition to the scan, trial holes were dug in certain sections to ‘ground truth’ the results. The results of the scan were consolidated and displayed on a screen ready for visitors to see. The findings were extremely fascinating. The tree is rooting down to 2m. Interestingly, the roots are all below 15cm deep, which is not surprising as the ground is so compacted; this well-used area sees a mixture of pedestrian and vehicular traffic. It is well documented that heavily compacted soil dissuades roots from growing, and it is evident that this is the case with this tree. Figure 1 illustrates a ‘virtual trench’ of one of the scan lines. This compaction was confirmed by our trial pit hand digging. A series of concentric circles, 1m apart, around the tree were scanned. Due to the presence of obstacles, this scan did not extend as far out as we would have wished. Therefore, in addition a straight line from the trunk out to 23m was also scanned. This straight-line scan found roots along its entire length. This adds to a growing body of evidence illustrating the full extent of root systems. Previous scans undertaken by Sharon Hosegood Associates found roots from an oak at the Burghley Estate (Lincolnshire) out to 22m and, more recently, on trees in Bournemouth out to 15 × stem diameter. It is clear, based on this research on veteran trees (oaks and a yew), that the standard 12 × stem diameter is not a reflection of rooting patterns of open-grown veteran trees. TreeRadar only picks up roots with a diameter greater than 20mm (other antennae are more sensitive, but data interpretation is more complex). It should be mentioned that this is just part of the picture; tree root health is so much more than woody roots. Figure 1: Cross-section of a scan line. The Red triangles are roots. All roots are below 15cm deep, and generally between 15cm and 1m deep Figure 2: Root morphology map of the Westonbirt veteran oak. This is not the full extent of the roots, but the inner circle of the rooting area. Note that some of the roots are from the adjacent oak. Root protection on development sites If the Westonbirt veteran oak was on a development site, and the guidance for calculating the root protection area from BS5837:2012 was followed, this tree would receive a minimum root protection area of 452m2 (circle with a 12m radius). Assuming the guidance from the standing advice was followed, a minimum root protection area of 707m2 (circle with a 15m radius) would be provided. Picture 1 illustrates the different root protection areas alongside the known minimum root spread; significant roots (>20mm) were still being detected 23m from tree. Using this tree as an example, it is clear that part of the root and mycorrhizal system would be lost if only the roots in these root protection areas were retained. It would be considered poor practice to prescribe the same recommendation for crown management of all trees across the country based on an arbitrary calculation, but this is seen as standard practice for the rooting environment. What is unclear is at what point the balance shifts from ‘recoverable damage’ to ‘deterioration’. The timescales these trees operate over can span several human lifetimes, making it difficult to link cause and effect. Trees can be pushed past the tipping point, but may take tens of years for symptoms to show. Stress means pests and diseases Ted Green, Ancient Tree Forum founder-president, spoke at the 2017 Arboricultural Association Amenity conference emphasising five words: ‘Stress means pests and diseases’. This simple mantra should be adopted by all who are responsible for managing trees. The importance of a healthy soil environment is highlighted by three disorders that are of increasing concern: Powdery mildew of oak (Erisyphe alphitoides and E. quercicola) has increased in prevalence in the past 30 years. These fungi are particularly damaging to the lammas leaves on oak, giving them a white powdery covering. Among other damaging effects these fungi have, the fungal mycelium causes constant evaporation of water that would normally be regulated by the leaves’ stomata, thereby exacerbating the impacts of dry summers. Powdery mildew is most prevalent in the south-east, the area of the country with the lowest rainfall. Chalara dieback of ash (Hymenoscyphus fraxineus) has made headline news since 2012 when it was first discovered in the UK. First thought only to affect younger trees or those recently planted out from nurseries, it has subsequently been found that this fungus is not limited to these trees. Research has shown that stressed trees are more susceptible to the fungus. Oak decline has presented itself in various episodes during the last 100 years. The symptoms of this disorder are dieback in the canopy and stem bleeds. Until recently this disorder was little understood. However, work by Monck & Fay has presented evidence to show an increase in symptoms related to reduced soil health. Whilst not a panacea, a healthy soil (and associated extensive root/mycorrhizae system) reduces the likelihood of trees succumbing to these disorders; a good supply of water from the roots can help buffer the potential impacts of powdery mildew, and healthy soils reduce the likelihood of stress, reducing potential impacts of ash dieback and oak decline. Conclusion More information is required to enable us to move away from an arbitrary calculation and towards an evidence-based approach, informed by individual circumstances. Only then can we determine how far roots of veteran trees grow, and how many roots can be damaged or lost before the tree deteriorates. The building of anecdotal evidence, and increasing use of non-invasive technology such as the TreeRadar and ARBOTOM, provides the opportunity to accurately identify the location of roots for an individual tree. However, until such a time that this becomes commonplace, a precautionary principle approach is suggested. The adoption of the larger root protection area, as a minimum, to enable the retention of healthy soil and root/mycorrhizal system will provide these trees with the greatest chance for survival, not just during the next 10, 20 or 40 years but for the rest of their lifespan. Next time Supporters of the Ancient Tree Forum have gathered anecdotal evidence over a number of years illustrating the distances roots of veteran trees can travel; the Westonbirt oak is yet another case to add to the list. In the next edition of The ARB Magazine we will present some of the examples collated to date, with the aim of stimulating discussion on this topic. If readers have examples they feel would be valuable to the discussion, especially if these can be supported by photographs or written records, the Ancient Tree Forum would like to hear from you. Please email training@ancienttreeforum.co.uk. Note Paragraph 118 of the National Planning Policy Framework (2012) states: ‘When determining planning applications, local planning authorities should aim to conserve and enhance biodiversity by applying the following principles: … planning permission should be refused for development resulting in the loss or deterioration of irreplaceable habitats, including ancient woodland and the loss of aged or veteran trees found outside ancient woodland, unless the need for, and benefits of, the development in that location clearly outweigh the loss …’. Ancient woodland and veteran trees: protecting them from development, standing advice from the Forestry Commission and Natural England, reads: ‘… leaving a buffer zone at least 15 times larger than the diameter of a veteran tree or 5m from the edge of its canopy, if that’s greater’. In addition to recommending a larger multiplication figure, this advice does not set a maximum radius (BS5837:2012 sets this at 15m). Acknowledgements The Ancient Tree Forum would like to thank Sharon Hosegood Associates Ltd and Frank Rinn (RINNTECH) for attending the show to help map the veteran tree’s roots with the TreeRadar and ARBOTOM. Thanks also go to Paul Melarange, Luke Steer, Luke Barley, Sally Clark, Jill Butler and Ted Green for helping deliver such a successful programme of events at the Ancient Tree Forum tent. Article originally posted at https://www.trees.org.uk/
  4. The Arboricultural Association

    Root Protection for Veteran Trees

    A common conflict between development and veteran trees centres on the protection of the rooting environment. Difficulties exist due to the subterranean nature of this important part of the tree, concealing it from view. The Ancient Tree Forum and the Woodland Trust have long drawn attention to this often overlooked part of the tree, emphasising the importance of healthy soil, mycorrhizae and roots and the need for appropriate management of the land around veteran trees. In November, the Forestry Commission and Natural England updated their standing advice, Ancient woodland and veteran trees: protecting them from development. This document sets out the principles planning authorities should consider for developments affecting ancient woodland and veteran trees. The standing advice picks up from the National Planning Policy Framework with regards to the importance of veteran trees and the need for their protection. Together these documents state that planning permission should be refused if proposals involve the loss or deterioration of veteran trees, unless the need for, and benefit of, development in that location clearly outweigh the loss (see the note at the end of this article for more info). The loss of a veteran tree is clear cut and easily defined; in such circumstances local planning authorities would weigh up the loss against the need for and benefit of development when determining an application. However, the deterioration of veteran trees is perhaps less black and white. The standing advice requires developers to identify aged and veteran trees as part of tree surveys and to show different root protection areas on plans. The Ancient Tree Forum and the Woodland Trust consider that all ancient trees and mature veteran trees should be recorded in Category A3 in accordance with BS5837:2012. The standing advice also recommends a larger root protection area for veteran trees, ‘at least 15 times larger than the diameter of a veteran tree’. Previous guidance – BS5837:2012 – recommends the minimum root protection area to be a 12 times larger with a cap at 707m2 (15m radius). However, do root protection areas based on an arbitrary calculation enable an informed decision to be made regarding the retention of veteran trees without ‘deterioration’? TreeRadar at the ARB Show In 2017 the Ancient Tree Forum attended the ARB Show with the aim of encouraging arborists to think about the rooting environment around veteran trees. A number of talks and demonstrations were held at the Ancient Tree Forum tent, which was situated adjacent to two veteran oak trees. TreeRadar in action Sharon Hosegood, Ian Lee and Noel Durdant-Hollamby from Sharon Hosegood Associates Ltd joined the Ancient Tree Forum for the weekend. Sharon and Co. brought with them their TreeRadar. This piece of equipment is able to record live tree roots, in excess of 20mm diameter, down to a depth of 3m, enabling the root system of a tree to be mapped without excavation. The aim for the weekend was to investigate the extent of the root system of one of the veteran trees and share the findings with attendees of the show. In advance of the show Sharon and Ian set about scanning the land around the tree to produce a map of the tree’s roots. In addition to the scan, trial holes were dug in certain sections to ‘ground truth’ the results. The results of the scan were consolidated and displayed on a screen ready for visitors to see. The findings were extremely fascinating. The tree is rooting down to 2m. Interestingly, the roots are all below 15cm deep, which is not surprising as the ground is so compacted; this well-used area sees a mixture of pedestrian and vehicular traffic. It is well documented that heavily compacted soil dissuades roots from growing, and it is evident that this is the case with this tree. Figure 1 illustrates a ‘virtual trench’ of one of the scan lines. This compaction was confirmed by our trial pit hand digging. A series of concentric circles, 1m apart, around the tree were scanned. Due to the presence of obstacles, this scan did not extend as far out as we would have wished. Therefore, in addition a straight line from the trunk out to 23m was also scanned. This straight-line scan found roots along its entire length. This adds to a growing body of evidence illustrating the full extent of root systems. Previous scans undertaken by Sharon Hosegood Associates found roots from an oak at the Burghley Estate (Lincolnshire) out to 22m and, more recently, on trees in Bournemouth out to 15 × stem diameter. It is clear, based on this research on veteran trees (oaks and a yew), that the standard 12 × stem diameter is not a reflection of rooting patterns of open-grown veteran trees. TreeRadar only picks up roots with a diameter greater than 20mm (other antennae are more sensitive, but data interpretation is more complex). It should be mentioned that this is just part of the picture; tree root health is so much more than woody roots. Figure 1: Cross-section of a scan line. The Red triangles are roots. All roots are below 15cm deep, and generally between 15cm and 1m deep Figure 2: Root morphology map of the Westonbirt veteran oak. This is not the full extent of the roots, but the inner circle of the rooting area. Note that some of the roots are from the adjacent oak. Root protection on development sites If the Westonbirt veteran oak was on a development site, and the guidance for calculating the root protection area from BS5837:2012 was followed, this tree would receive a minimum root protection area of 452m2 (circle with a 12m radius). Assuming the guidance from the standing advice was followed, a minimum root protection area of 707m2 (circle with a 15m radius) would be provided. Picture 1 illustrates the different root protection areas alongside the known minimum root spread; significant roots (>20mm) were still being detected 23m from tree. Using this tree as an example, it is clear that part of the root and mycorrhizal system would be lost if only the roots in these root protection areas were retained. It would be considered poor practice to prescribe the same recommendation for crown management of all trees across the country based on an arbitrary calculation, but this is seen as standard practice for the rooting environment. What is unclear is at what point the balance shifts from ‘recoverable damage’ to ‘deterioration’. The timescales these trees operate over can span several human lifetimes, making it difficult to link cause and effect. Trees can be pushed past the tipping point, but may take tens of years for symptoms to show. Stress means pests and diseases Ted Green, Ancient Tree Forum founder-president, spoke at the 2017 Arboricultural Association Amenity conference emphasising five words: ‘Stress means pests and diseases’. This simple mantra should be adopted by all who are responsible for managing trees. The importance of a healthy soil environment is highlighted by three disorders that are of increasing concern: Powdery mildew of oak (Erisyphe alphitoides and E. quercicola) has increased in prevalence in the past 30 years. These fungi are particularly damaging to the lammas leaves on oak, giving them a white powdery covering. Among other damaging effects these fungi have, the fungal mycelium causes constant evaporation of water that would normally be regulated by the leaves’ stomata, thereby exacerbating the impacts of dry summers. Powdery mildew is most prevalent in the south-east, the area of the country with the lowest rainfall. Chalara dieback of ash (Hymenoscyphus fraxineus) has made headline news since 2012 when it was first discovered in the UK. First thought only to affect younger trees or those recently planted out from nurseries, it has subsequently been found that this fungus is not limited to these trees. Research has shown that stressed trees are more susceptible to the fungus. Oak decline has presented itself in various episodes during the last 100 years. The symptoms of this disorder are dieback in the canopy and stem bleeds. Until recently this disorder was little understood. However, work by Monck & Fay has presented evidence to show an increase in symptoms related to reduced soil health. Whilst not a panacea, a healthy soil (and associated extensive root/mycorrhizae system) reduces the likelihood of trees succumbing to these disorders; a good supply of water from the roots can help buffer the potential impacts of powdery mildew, and healthy soils reduce the likelihood of stress, reducing potential impacts of ash dieback and oak decline. Conclusion More information is required to enable us to move away from an arbitrary calculation and towards an evidence-based approach, informed by individual circumstances. Only then can we determine how far roots of veteran trees grow, and how many roots can be damaged or lost before the tree deteriorates. The building of anecdotal evidence, and increasing use of non-invasive technology such as the TreeRadar and ARBOTOM, provides the opportunity to accurately identify the location of roots for an individual tree. However, until such a time that this becomes commonplace, a precautionary principle approach is suggested. The adoption of the larger root protection area, as a minimum, to enable the retention of healthy soil and root/mycorrhizal system will provide these trees with the greatest chance for survival, not just during the next 10, 20 or 40 years but for the rest of their lifespan. Next time Supporters of the Ancient Tree Forum have gathered anecdotal evidence over a number of years illustrating the distances roots of veteran trees can travel; the Westonbirt oak is yet another case to add to the list. In the next edition of The ARB Magazine we will present some of the examples collated to date, with the aim of stimulating discussion on this topic. If readers have examples they feel would be valuable to the discussion, especially if these can be supported by photographs or written records, the Ancient Tree Forum would like to hear from you. Please email training@ancienttreeforum.co.uk. Note Paragraph 118 of the National Planning Policy Framework (2012) states: ‘When determining planning applications, local planning authorities should aim to conserve and enhance biodiversity by applying the following principles: … planning permission should be refused for development resulting in the loss or deterioration of irreplaceable habitats, including ancient woodland and the loss of aged or veteran trees found outside ancient woodland, unless the need for, and benefits of, the development in that location clearly outweigh the loss …’. Ancient woodland and veteran trees: protecting them from development, standing advice from the Forestry Commission and Natural England, reads: ‘… leaving a buffer zone at least 15 times larger than the diameter of a veteran tree or 5m from the edge of its canopy, if that’s greater’. In addition to recommending a larger multiplication figure, this advice does not set a maximum radius (BS5837:2012 sets this at 15m). Acknowledgements The Ancient Tree Forum would like to thank Sharon Hosegood Associates Ltd and Frank Rinn (RINNTECH) for attending the show to help map the veteran tree’s roots with the TreeRadar and ARBOTOM. Thanks also go to Paul Melarange, Luke Steer, Luke Barley, Sally Clark, Jill Butler and Ted Green for helping deliver such a successful programme of events at the Ancient Tree Forum tent. Article originally posted at https://www.trees.org.uk/ View full article
  5. The Arboricultural Association

    Arborists reminded of OPM hazard

    Arborists in south-east England are being reminded to protect themselves this spring and summer from contact with oak processionary moth caterpillar hairs (OPM). They are also encouraged to help control the pest by reporting sightings to the Forestry Commission, and to take care not to spread the pest when removing oak material from tree surgery sites. As well as damaging oak trees by feeding on the leaves, the caterpillar can impact human and animal health: contact with its hairs can cause itching skin rashes, eye irritations, sore throats and other health problems. In rare cases they can cause breathing difficulties and allergic reactions. Arborists in the affected areas are therefore strongly advised to wear protective clothing. The hairs can be blown on the wind, left in the caterpillars’ nests on and under oak trees, and can stick to bark, clothing and climbing ropes. The greatest risk period is May to July, although nests should not be approached at any time because the hairs remain active for many months. The known affected areas include much of greater London and parts of Hertfordshire, Buckinghamshire, West Berkshire, Surrey and Essex. The affected areas are organised into ‘Core’, ‘Control’ and ‘Protected’ Zones, and maps and explanations of the regulations and procedures applying in each zone are available in the oak tree owners’ manual at www.forestry.gov.uk/opmmanual. OPM nests and silken webbing trails. Nests can be attached to trunks and branches anywhere on the tree, but not among the foliage. ©Forestry Commission/Crown copyright. OPM caterpillars in classic procession. ©Henry Kuppen/Forestry Commission. Report it Andrew Hoppit, OPM programme manager, said arborists are well placed to help control the pest by reporting sightings, but he advised caution. We need reports of the caterpillars and their nests from arborists, tree surgeons and ground-care workers. However, we don’t advise them to try removing them themselves. Removal requires specialist equipment and training to be done effectively.’ Mr Hoppit added, Moving infested arisings from oak tree surgery is one way in which OPM can be spread, so I urge arborists in the affected areas to take the precautions recommended on our website to ensure they don’t accidentally spread the pest to new areas.’ Arborists and tree surgeons who plan to fell or prune trees in the affected areas must contact the Forestry Commission’s Plant Health Service beforehand on plant.health@forestry.gsi.gov.uk or 0300 067 5155 for advice about safe removal of the material. They should also familiarise themselves with the regulations and good practice guidance which apply to handling and disposal of oak material in the affected areas, at www.forestry.gov.uk/opm. A video on the website depicts a number of views of OPM caterpillars and nests which arborists might encounter. For more information… An OPM ‘manual’ of surveying for and managing OPM, including health and safety guidance, is available at www.forestry.gov.uk/opmmanual Sightings should be reported with the Forestry Commission’s Tree Alert online form available from www.forestry.gov.uk/opm. Anyone who cannot use Tree Alert (which requires a photograph) may email reports to opm@forestry.gsi.gov.uk, or telephone them to 0300 067 4442. Health advice is available from the ‘Insects that bite or sting’ area of the NHS Choices website, www.nhs.uk/livewell. Further information, including identification guidance and maps, is available from www.forestry.gov.uk/opm. Don’t underestimate OPM AA Technical Officer Paul McBride sits on the OPM Strategic Advisory Group, which met in December 2017. Here is his report on that meeting. When spotted early enough, isolated oak processionary moth (OPM) outbreaks can be contained, so it is vitally important that arborists and anyone inspecting trees can identify the signs of defoliation, nests and the caterpillar stage. A report can be submitted via www.forestry.gov.uk/treealert and completing the form or emailing opm@forestry.gsi.gov.uk. Tree surveyors should vary the timing and frequency of survey visits on oak trees to coincide with nest formation from early June to August. Any arboricultural contractors regularly operating within an area roughly speaking 12 miles outside of the M25 need to be aware of the risk of exposure to the irritant hairs that the caterpillar stage of OPM produces after emergence in March/April. Irritant hairs accumulate in nests from June/July and can remain on the tree for a number of years if undetected. Sometimes the nests disintegrate slowly and sometimes they fall to the floor complete. Hairs could be dispersed up to 200m from the affected tree, so it is not surprising that human health effects will be under-reported as those affected will often not know the association. Arboricultural contract managers and site supervisors should not underestimate the risk of repeated exposure. Individuals who regularly work on infected trees can potentially become so sensitised that they may not be able to continue working where OPM is present. Please follow the guidance note produced by the London Tree Officers Association (LTOA): operatives must wear the appropriate level of PPE at all times when they might be exposed – www.ltoa.org.uk. Biosecurity measures that help to prevent spread will need to be robustly implemented where contact occurs. Tree stock managers/owners within the Core Zone should continue to survey and control, but Statutory Plant Health Notices may not be issued. It is anticipated that such work will not generally be funded by Defra and this creates an opportunity for specialised contractors to remove nests. It would be preferred if such contractors could be ‘procurement approved’ by external assessment, so that clients can be reassured that appropriate systems are in place to protect the operatives involved and the public during nest removal operations. As continued spread from the Core Zone has been observed it may have to be accepted that eradication may not be sustainable in the longer term, and attention should turn to managing the exposure risk for human health. Managers should risk assess the potential for interaction and prioritise their resources accordingly. Observations that the caterpillars appear to prefer open-grown trees and woodland edge trees to heavily shaded trees may help to direct surveying priorities where resources are limited and public access levels are known (although any such assumption risks undermining efforts to eradicate). This may shift the emphasis to removing older nests where eradication has been unsuccessful. As the Control Zone is likely to increase radially by 20km for 2018 an increasing number of stakeholders will be affected. The LTOA has been working very hard at coordinating efforts to help limit the spread in and around London, but as the area affected spreads beyond London more people will need to get involved and communicate effectively. This does mean that some nurseries will be affected and controls on the movement of live plant material which could harbour the pest will be put in place when oak plant material is susceptible. As the time between a new report of OPM occurrence and putting in place a suitable response can be short (a few days), challenges remain to effectively control the pest population. Increasing capacity to deliver such controls seems an inevitable requirement. This article has been reproduced from pages 14 and 15 of the Spring 2018 – Issue 180 of the ARB Magazine. It is available to view digitally to our members at The ARB Magazine web page.
  6. The Arboricultural Association

    Arborists reminded of OPM hazard

    Arborists in south-east England are being reminded to protect themselves this spring and summer from contact with oak processionary moth caterpillar hairs (OPM). They are also encouraged to help control the pest by reporting sightings to the Forestry Commission, and to take care not to spread the pest when removing oak material from tree surgery sites. As well as damaging oak trees by feeding on the leaves, the caterpillar can impact human and animal health: contact with its hairs can cause itching skin rashes, eye irritations, sore throats and other health problems. In rare cases they can cause breathing difficulties and allergic reactions. Arborists in the affected areas are therefore strongly advised to wear protective clothing. The hairs can be blown on the wind, left in the caterpillars’ nests on and under oak trees, and can stick to bark, clothing and climbing ropes. The greatest risk period is May to July, although nests should not be approached at any time because the hairs remain active for many months. The known affected areas include much of greater London and parts of Hertfordshire, Buckinghamshire, West Berkshire, Surrey and Essex. The affected areas are organised into ‘Core’, ‘Control’ and ‘Protected’ Zones, and maps and explanations of the regulations and procedures applying in each zone are available in the oak tree owners’ manual at www.forestry.gov.uk/opmmanual. OPM nests and silken webbing trails. Nests can be attached to trunks and branches anywhere on the tree, but not among the foliage. ©Forestry Commission/Crown copyright. OPM caterpillars in classic procession. ©Henry Kuppen/Forestry Commission. Report it Andrew Hoppit, OPM programme manager, said arborists are well placed to help control the pest by reporting sightings, but he advised caution. We need reports of the caterpillars and their nests from arborists, tree surgeons and ground-care workers. However, we don’t advise them to try removing them themselves. Removal requires specialist equipment and training to be done effectively.’ Mr Hoppit added, Moving infested arisings from oak tree surgery is one way in which OPM can be spread, so I urge arborists in the affected areas to take the precautions recommended on our website to ensure they don’t accidentally spread the pest to new areas.’ Arborists and tree surgeons who plan to fell or prune trees in the affected areas must contact the Forestry Commission’s Plant Health Service beforehand on plant.health@forestry.gsi.gov.uk or 0300 067 5155 for advice about safe removal of the material. They should also familiarise themselves with the regulations and good practice guidance which apply to handling and disposal of oak material in the affected areas, at www.forestry.gov.uk/opm. A video on the website depicts a number of views of OPM caterpillars and nests which arborists might encounter. For more information… An OPM ‘manual’ of surveying for and managing OPM, including health and safety guidance, is available at www.forestry.gov.uk/opmmanual Sightings should be reported with the Forestry Commission’s Tree Alert online form available from www.forestry.gov.uk/opm. Anyone who cannot use Tree Alert (which requires a photograph) may email reports to opm@forestry.gsi.gov.uk, or telephone them to 0300 067 4442. Health advice is available from the ‘Insects that bite or sting’ area of the NHS Choices website, www.nhs.uk/livewell. Further information, including identification guidance and maps, is available from www.forestry.gov.uk/opm. Don’t underestimate OPM AA Technical Officer Paul McBride sits on the OPM Strategic Advisory Group, which met in December 2017. Here is his report on that meeting. When spotted early enough, isolated oak processionary moth (OPM) outbreaks can be contained, so it is vitally important that arborists and anyone inspecting trees can identify the signs of defoliation, nests and the caterpillar stage. A report can be submitted via www.forestry.gov.uk/treealert and completing the form or emailing opm@forestry.gsi.gov.uk. Tree surveyors should vary the timing and frequency of survey visits on oak trees to coincide with nest formation from early June to August. Any arboricultural contractors regularly operating within an area roughly speaking 12 miles outside of the M25 need to be aware of the risk of exposure to the irritant hairs that the caterpillar stage of OPM produces after emergence in March/April. Irritant hairs accumulate in nests from June/July and can remain on the tree for a number of years if undetected. Sometimes the nests disintegrate slowly and sometimes they fall to the floor complete. Hairs could be dispersed up to 200m from the affected tree, so it is not surprising that human health effects will be under-reported as those affected will often not know the association. Arboricultural contract managers and site supervisors should not underestimate the risk of repeated exposure. Individuals who regularly work on infected trees can potentially become so sensitised that they may not be able to continue working where OPM is present. Please follow the guidance note produced by the London Tree Officers Association (LTOA): operatives must wear the appropriate level of PPE at all times when they might be exposed – www.ltoa.org.uk. Biosecurity measures that help to prevent spread will need to be robustly implemented where contact occurs. Tree stock managers/owners within the Core Zone should continue to survey and control, but Statutory Plant Health Notices may not be issued. It is anticipated that such work will not generally be funded by Defra and this creates an opportunity for specialised contractors to remove nests. It would be preferred if such contractors could be ‘procurement approved’ by external assessment, so that clients can be reassured that appropriate systems are in place to protect the operatives involved and the public during nest removal operations. As continued spread from the Core Zone has been observed it may have to be accepted that eradication may not be sustainable in the longer term, and attention should turn to managing the exposure risk for human health. Managers should risk assess the potential for interaction and prioritise their resources accordingly. Observations that the caterpillars appear to prefer open-grown trees and woodland edge trees to heavily shaded trees may help to direct surveying priorities where resources are limited and public access levels are known (although any such assumption risks undermining efforts to eradicate). This may shift the emphasis to removing older nests where eradication has been unsuccessful. As the Control Zone is likely to increase radially by 20km for 2018 an increasing number of stakeholders will be affected. The LTOA has been working very hard at coordinating efforts to help limit the spread in and around London, but as the area affected spreads beyond London more people will need to get involved and communicate effectively. This does mean that some nurseries will be affected and controls on the movement of live plant material which could harbour the pest will be put in place when oak plant material is susceptible. As the time between a new report of OPM occurrence and putting in place a suitable response can be short (a few days), challenges remain to effectively control the pest population. Increasing capacity to deliver such controls seems an inevitable requirement. This article has been reproduced from pages 14 and 15 of the Spring 2018 – Issue 180 of the ARB Magazine. It is available to view digitally to our members at The ARB Magazine web page. View full article
  7. The Arboricultural Association

    Finding inspiration in Melbourne

    Article by Keith Sacre Ian Shears is the Manager of Urban Sustainability at Melbourne City Council. He is speaking at the AA’s Conference in Exeter this year. While I was at the Arb Australia Conference in May I spent some time with Ian. He exudes energy and enthusiasm, and his excitement at what is being achieved in Melbourne is immediately obvious. Sitting the other side of a desk from him, it was easy to become engaged and engrossed in the Melbourne urban forest story. If that story translates as well to the podium at conference then we are all in for a very inspiring and informative treat. Ian and his team of 50 manage an urban forest of some 75,000 trees and all the publicly owned green spaces in Melbourne. The landscape is a real mixture of historic gardens lined with significant avenues of trees planted in the mid-to-late 1800s, public open spaces adorned with the usual mixture of inner-city facilities and street trees – some old, some newly planted and a mixture of everything in between. It is impossible to be in Melbourne for any length of time and not to realise how important green space and trees are to the city; they collectively contribute to the vibrancy and bustle of the place which has a population of 130,000 but has to provide an infrastructure capable of meeting the demands of over a million workers and tourists. Yet, as with all cities, there are pressures. Many of the significant avenues are reaching the end of their useful life with 23% of the tree population estimated to come to the end of its useful life within 10 years. This estimate rises to 39% within 20 years. The city has a significant elm population with several magnificent avenues. It is estimated that 55% of these trees are in a state of severe decline and will need to be removed from the landscape within the next ten years. Almost 43% of the tree population comes from one family, the Myrtaceae, which includes Eucalyptus, Corymbia, Callistemon, Angophora and Melaleuca, all of which are vulnerable to myrtle rust, which has been found in Melbourne. While there are some 388 different species within the boundaries of the city it is recognised that London plane represents 75% of the trees within the central area and that just three families represent 63% of the total population. While the numbers, percentages and species may vary, these and other problems will not be unfamiliar to urban forest managers in the UK and are international in their constant repetition. What is unusual is the way Melbourne, through the inspiration of Ian Shears and his team, have set about addressing the situation and especially the problems associated with long-term urban forest management. The city has been extensively mapped for tree health, species composition, canopy cover and useful life expectancy. A limited i-Tree study of 982 trees in the city area provided an assessment of the ecosystem services being provided by the tree population and an estimate that the city’s trees have an amenity value of some 700million Australian dollars. Canopy cover has been assessed by precinct, with a variation between precincts of between just over 34% cover and less than 5%. It is impossible to fully explain in this article all the elements which make Melbourne such an interesting case study and it would take a better reporter than me to record everything Ian enthused about during our time together. You will have to attend the conference for that, but here is a flavour of the elements which appeared significant to me. Strategy, planting, maintenance First, Melbourne plants some 3,300 trees each year. These are all contract grown, giving the city the opportunity to select the species it actually wants to enhance the resilience of the tree population as a whole and to control the specification of the trees supplied. The vagaries of the market-place are removed. This practice is not commonly followed in the UK where many municipalities are dependent on ‘what the nursery industry’ has available at the time of supply. Melbourne’s practice enables the city to plan in advance. All of its trees are planted under contract with a three-year maintenance programme associated with the planting contract. This is not so unusual, but the fact that the tree planting is independently audited at the end of the contract period with the condition of the young trees assessed before the city accepts ownership is a significant difference. Maybe something we can learn here? I was told a story, not confirmed, that the first such audit found that 46% of the young trees were in an unacceptable condition and that the contractor responsible had to make good before being sacked. The city has a clear urban forest strategy plan with six defined targets. These are: increase canopy cover to 40% by 2040 increase urban forest diversity improve vegetation health with 90% of Melbourne’s trees being healthy by 2040 improve soil moisture and water quality improve urban ecology inform and consult the community This strategy is firmly embedded within a well-defined city policy framework. But unlike many tree strategies which are just wish lists, the Melbourne plan appears to have real meaning and, more importantly, clout. So why should this be the case? Making the case It would appear that there is both serious political engagement and serious community engagement and buy-in to the programme. Again we come back to the communication skills, energy and enthusiasm of Ian Shears himself. He explained in some detail the amount of time he has spent engaging with politicians, canvassing and making the case for the urban forest and its importance to Melbourne. He showed a series of photographs which just happened to be taken of trees near to the areas where politicians lived. These trees were cleverly Photoshopped out, leaving the stark, naked, tree-free streets clearly visible and demonstrating the impact of ‘doing nothing’. Ian than went on to describe, again in some detail, the amount of time, energy and effort he and his team have expended in speaking to community groups, residents’ associations and the like, again making the case for the urban forest and illustrating how important that forest actually is to the community and the many benefits residents gain from it. It is interesting to note that each of the precincts referred to earlier now has its own management plan composed of action points and priorities for urban forest development, constructed and put together under the guidance and support of Ian and his team. As with all reports from foreign parts, the traveller, in this case me, can only take a snapshot and is largely reliant on stories told and limited personal observation. The detail is always veiled and partially camouflaged, but on this occasion, I have met Ian and members of his team, seen the impressive documentation, more importantly perhaps walked as much of Melbourne as it is possible to walk in just a few days, and observed, photographed and made just a few notes. My observations confirm much of what I had been told. The city is vibrant, the green spaces are well used, there is extensive tree planting, and management practices have been adapted to conserve some of the significant ageing avenues within the historic gardens – and incidentally, the botanic garden has a fine collection of trees. Many of you will not be able to visit Melbourne yourselves but Ian Shears is speaking on ‘Transitioning Melbourne’s urban landscapes – climate change for future liveability’ at the Association’s Conference on 10–13 September. I believe it would be worth coming to listen and have the opportunity to question him. His experience and initiatives offer a model from which we can all learn something.
  8. The Arboricultural Association

    Finding inspiration in Melbourne

    Article by Keith Sacre Ian Shears is the Manager of Urban Sustainability at Melbourne City Council. He is speaking at the AA’s Conference in Exeter this year. While I was at the Arb Australia Conference in May I spent some time with Ian. He exudes energy and enthusiasm, and his excitement at what is being achieved in Melbourne is immediately obvious. Sitting the other side of a desk from him, it was easy to become engaged and engrossed in the Melbourne urban forest story. If that story translates as well to the podium at conference then we are all in for a very inspiring and informative treat. Ian and his team of 50 manage an urban forest of some 75,000 trees and all the publicly owned green spaces in Melbourne. The landscape is a real mixture of historic gardens lined with significant avenues of trees planted in the mid-to-late 1800s, public open spaces adorned with the usual mixture of inner-city facilities and street trees – some old, some newly planted and a mixture of everything in between. It is impossible to be in Melbourne for any length of time and not to realise how important green space and trees are to the city; they collectively contribute to the vibrancy and bustle of the place which has a population of 130,000 but has to provide an infrastructure capable of meeting the demands of over a million workers and tourists. Yet, as with all cities, there are pressures. Many of the significant avenues are reaching the end of their useful life with 23% of the tree population estimated to come to the end of its useful life within 10 years. This estimate rises to 39% within 20 years. The city has a significant elm population with several magnificent avenues. It is estimated that 55% of these trees are in a state of severe decline and will need to be removed from the landscape within the next ten years. Almost 43% of the tree population comes from one family, the Myrtaceae, which includes Eucalyptus, Corymbia, Callistemon, Angophora and Melaleuca, all of which are vulnerable to myrtle rust, which has been found in Melbourne. While there are some 388 different species within the boundaries of the city it is recognised that London plane represents 75% of the trees within the central area and that just three families represent 63% of the total population. While the numbers, percentages and species may vary, these and other problems will not be unfamiliar to urban forest managers in the UK and are international in their constant repetition. #jscode# What is unusual is the way Melbourne, through the inspiration of Ian Shears and his team, have set about addressing the situation and especially the problems associated with long-term urban forest management. The city has been extensively mapped for tree health, species composition, canopy cover and useful life expectancy. A limited i-Tree study of 982 trees in the city area provided an assessment of the ecosystem services being provided by the tree population and an estimate that the city’s trees have an amenity value of some 700million Australian dollars. Canopy cover has been assessed by precinct, with a variation between precincts of between just over 34% cover and less than 5%. It is impossible to fully explain in this article all the elements which make Melbourne such an interesting case study and it would take a better reporter than me to record everything Ian enthused about during our time together. You will have to attend the conference for that, but here is a flavour of the elements which appeared significant to me. Strategy, planting, maintenance First, Melbourne plants some 3,300 trees each year. These are all contract grown, giving the city the opportunity to select the species it actually wants to enhance the resilience of the tree population as a whole and to control the specification of the trees supplied. The vagaries of the market-place are removed. This practice is not commonly followed in the UK where many municipalities are dependent on ‘what the nursery industry’ has available at the time of supply. Melbourne’s practice enables the city to plan in advance. All of its trees are planted under contract with a three-year maintenance programme associated with the planting contract. This is not so unusual, but the fact that the tree planting is independently audited at the end of the contract period with the condition of the young trees assessed before the city accepts ownership is a significant difference. Maybe something we can learn here? I was told a story, not confirmed, that the first such audit found that 46% of the young trees were in an unacceptable condition and that the contractor responsible had to make good before being sacked. The city has a clear urban forest strategy plan with six defined targets. These are: increase canopy cover to 40% by 2040 increase urban forest diversity improve vegetation health with 90% of Melbourne’s trees being healthy by 2040 improve soil moisture and water quality improve urban ecology inform and consult the community This strategy is firmly embedded within a well-defined city policy framework. But unlike many tree strategies which are just wish lists, the Melbourne plan appears to have real meaning and, more importantly, clout. So why should this be the case? Making the case It would appear that there is both serious political engagement and serious community engagement and buy-in to the programme. Again we come back to the communication skills, energy and enthusiasm of Ian Shears himself. He explained in some detail the amount of time he has spent engaging with politicians, canvassing and making the case for the urban forest and its importance to Melbourne. He showed a series of photographs which just happened to be taken of trees near to the areas where politicians lived. These trees were cleverly Photoshopped out, leaving the stark, naked, tree-free streets clearly visible and demonstrating the impact of ‘doing nothing’. Ian than went on to describe, again in some detail, the amount of time, energy and effort he and his team have expended in speaking to community groups, residents’ associations and the like, again making the case for the urban forest and illustrating how important that forest actually is to the community and the many benefits residents gain from it. It is interesting to note that each of the precincts referred to earlier now has its own management plan composed of action points and priorities for urban forest development, constructed and put together under the guidance and support of Ian and his team. As with all reports from foreign parts, the traveller, in this case me, can only take a snapshot and is largely reliant on stories told and limited personal observation. The detail is always veiled and partially camouflaged, but on this occasion, I have met Ian and members of his team, seen the impressive documentation, more importantly perhaps walked as much of Melbourne as it is possible to walk in just a few days, and observed, photographed and made just a few notes. My observations confirm much of what I had been told. The city is vibrant, the green spaces are well used, there is extensive tree planting, and management practices have been adapted to conserve some of the significant ageing avenues within the historic gardens – and incidentally, the botanic garden has a fine collection of trees. Many of you will not be able to visit Melbourne yourselves but Ian Shears is speaking on ‘Transitioning Melbourne’s urban landscapes – climate change for future liveability’ at the Association’s Conference on 10–13 September. I believe it would be worth coming to listen and have the opportunity to question him. His experience and initiatives offer a model from which we can all learn something. View full article
  9. The Arboricultural Association

    Trees and footways: a tree officer’s view

    Article by John Parker, Chair, London Tree Officers Association All of us in the arboricultural industry are aware of the ecosystem services delivered by the urban forest. The environmental, economic and social benefits enjoyed by all of those who live, work and play near trees. Yet we must also acknowledge the disadvantages, real and perceived, which can be brought about as a result of trees. As the typical first point of contact between the public and the arboricultural industry, tree officers know better than most some of the traditional complaints. Blocked light, interrupted TV reception, falling leaves and fruit, funny smells, disagreements with pigeons; the list goes on. One problem associated with street trees has received a lot of recent coverage: the conflict between tree roots and the footway, and the different ways of managing this conflict. This is an extremely common issue and one which we all know too well. It goes without saying that it is essential that pedestrians and other road users are able to travel safely. Particular consideration should be given to those with mobility difficulties or the partially sighted. As with anything in life, the advantages and disadvantages have to be weighed up carefully before taking action, and there is usually more than one solution to a problem. Conflicts between tree roots and pavements usually have their origin right at the beginning, at the time of planting. As far as is reasonably practicable the pit – including the pit surface – should be designed to maximise the chances of establishment and minimise the risk of future problems. It should be obvious that planting specifications for street trees should be determined by an appropriately qualified and experienced tree specialist, usually the relevant tree officer. Right place, right tree, right expert. Mature trees and footways When planting new trees we are in the fortunate position of being able to try to avoid the mistakes of the past. However, this is obviously not an option when dealing with existing trees, some of which were planted decades or centuries ago. How do we deal with those semi-mature and mature trees which are causing problems to our footways? What is the solution to the conflict? The most straightforward answer would be to cut all of the trees down. No tree, no issue. But that would, of course, be short-sighted in the extreme, and nothing more than environmental and cultural vandalism. Removing a mature tree and replacing it with a single sapling is not really replacing it at all. We know that some of the key ecosystem services delivered by trees – such as air quality and urban cooling, to name but two – are positively correlated to canopy size. This is why there has been such an emphasis on increasing canopy cover in recent years. To fully ‘replace’ the canopy volume of a mature tree in the short term would likely require the planting of hundreds of trees in the vicinity of the original – an impossibility in an urban environment with all of the challenges and restrictions on space that we have to contend with. Canopy targets will not be met by tree planting alone; retention of existing trees is just as important. In addition to the environmental, social and economic considerations we also have to factor in the political costs of tree removal. It can be a blessing and a curse to tree officers that certain sections of their communities are so passionate about trees! The urban forest comes with a cost, but so does its absence. Any perceived saving on avoiding footway maintenance or pruning is surely wiped out by the additional costs associated with stormwater management, air conditioning, healthcare, crime, traffic accidents and so on. Problem solving It is worth remembering that there are several systems for calculating a monetary value for trees, such as the CAVAT method developed by the London Tree Officers Association. When repeated over a number of years this can show the depreciating value of a tree which has been over-pruned or damaged in some way. Conversely, CAVAT can demonstrate the fact that as the tree grows, so does its value. Replacing a mature tree with a sapling does not just negatively impact ecosystem services, it reduces asset value. Assigning a monetary value to a tree can also be used in cost comparison; the engineering solution or new surface material required to retain the tree might cost £25k and be deemed too expensive, but if the tree at risk of removal is regarded as an asset worth £100k then the engineering work starts to look like a bargain. One of the many roles of the tree officer is that of problem solver. Sometimes it may indeed be the case that a tree has to be removed because of damage it has caused to the footway, but those instances are extremely rare and removal should be regarded as an absolute last resort. A wide range of options is available which will allow both the footway and tree to continue to deliver their benefits to the urban environment. Space does not permit a detailed exploration of these options, but a brief summary can be given. Sometimes simply widening the tree pit is enough; sometimes root manipulation or pruning will resolve the situation. Carefully raising the footway or removing the displaced kerb might be an option in some cases. One of the most common solutions is to replace the damaged footway material with something less likely to cause a problem, perhaps the most obvious choice being to remove lifting slabs and their associated trip hazard and replace them with asphalt. Yes, it will eventually lift and crack and need to be replaced, but this is a small price to pay in exchange for being able to retain a healthy mature street tree. When it comes to materials immediately around the base of the tree there are many alternatives available. Some of these are explored in the forthcoming LTOA publication Surface materials around trees in hard landscapes. This document analyses some of the advantages and disadvantages of the most commonly used materials, including topsoil, organic mulch, inorganic mulch, self-binding gravel, resin-bound gravel and bound rubber crumb. The conclusion – spoiler alert – is that there is no tree pit panacea. No one material is suitable for all situations. So – what is the solution to the root versus footway conflict? Depending on the specific problem there will likely be several potential solutions. Removing a healthy tree is rarely one of them. The challenge, as always, is for us as an industry to continue to promote the importance of trees as a key component – the key component – of green infrastructure; to make the argument that trees are an asset as important to the urban environment as lamp columns, drains and flat footways; and to ensure that our urban forest is managed by the right people, equipped with the right resources.
  10. The Arboricultural Association

    Trees and footways: a tree officer’s view

    Article by John Parker, Chair, London Tree Officers Association All of us in the arboricultural industry are aware of the ecosystem services delivered by the urban forest. The environmental, economic and social benefits enjoyed by all of those who live, work and play near trees. Yet we must also acknowledge the disadvantages, real and perceived, which can be brought about as a result of trees. As the typical first point of contact between the public and the arboricultural industry, tree officers know better than most some of the traditional complaints. Blocked light, interrupted TV reception, falling leaves and fruit, funny smells, disagreements with pigeons; the list goes on. One problem associated with street trees has received a lot of recent coverage: the conflict between tree roots and the footway, and the different ways of managing this conflict. This is an extremely common issue and one which we all know too well. It goes without saying that it is essential that pedestrians and other road users are able to travel safely. Particular consideration should be given to those with mobility difficulties or the partially sighted. As with anything in life, the advantages and disadvantages have to be weighed up carefully before taking action, and there is usually more than one solution to a problem. #jscode# Conflicts between tree roots and pavements usually have their origin right at the beginning, at the time of planting. As far as is reasonably practicable the pit – including the pit surface – should be designed to maximise the chances of establishment and minimise the risk of future problems. It should be obvious that planting specifications for street trees should be determined by an appropriately qualified and experienced tree specialist, usually the relevant tree officer. Right place, right tree, right expert. Mature trees and footways When planting new trees we are in the fortunate position of being able to try to avoid the mistakes of the past. However, this is obviously not an option when dealing with existing trees, some of which were planted decades or centuries ago. How do we deal with those semi-mature and mature trees which are causing problems to our footways? What is the solution to the conflict? The most straightforward answer would be to cut all of the trees down. No tree, no issue. But that would, of course, be short-sighted in the extreme, and nothing more than environmental and cultural vandalism. Removing a mature tree and replacing it with a single sapling is not really replacing it at all. We know that some of the key ecosystem services delivered by trees – such as air quality and urban cooling, to name but two – are positively correlated to canopy size. This is why there has been such an emphasis on increasing canopy cover in recent years. To fully ‘replace’ the canopy volume of a mature tree in the short term would likely require the planting of hundreds of trees in the vicinity of the original – an impossibility in an urban environment with all of the challenges and restrictions on space that we have to contend with. Canopy targets will not be met by tree planting alone; retention of existing trees is just as important. In addition to the environmental, social and economic considerations we also have to factor in the political costs of tree removal. It can be a blessing and a curse to tree officers that certain sections of their communities are so passionate about trees! The urban forest comes with a cost, but so does its absence. Any perceived saving on avoiding footway maintenance or pruning is surely wiped out by the additional costs associated with stormwater management, air conditioning, healthcare, crime, traffic accidents and so on. Problem solving It is worth remembering that there are several systems for calculating a monetary value for trees, such as the CAVAT method developed by the London Tree Officers Association. When repeated over a number of years this can show the depreciating value of a tree which has been over-pruned or damaged in some way. Conversely, CAVAT can demonstrate the fact that as the tree grows, so does its value. Replacing a mature tree with a sapling does not just negatively impact ecosystem services, it reduces asset value. Assigning a monetary value to a tree can also be used in cost comparison; the engineering solution or new surface material required to retain the tree might cost £25k and be deemed too expensive, but if the tree at risk of removal is regarded as an asset worth £100k then the engineering work starts to look like a bargain. One of the many roles of the tree officer is that of problem solver. Sometimes it may indeed be the case that a tree has to be removed because of damage it has caused to the footway, but those instances are extremely rare and removal should be regarded as an absolute last resort. A wide range of options is available which will allow both the footway and tree to continue to deliver their benefits to the urban environment. Space does not permit a detailed exploration of these options, but a brief summary can be given. Sometimes simply widening the tree pit is enough; sometimes root manipulation or pruning will resolve the situation. Carefully raising the footway or removing the displaced kerb might be an option in some cases. One of the most common solutions is to replace the damaged footway material with something less likely to cause a problem, perhaps the most obvious choice being to remove lifting slabs and their associated trip hazard and replace them with asphalt. Yes, it will eventually lift and crack and need to be replaced, but this is a small price to pay in exchange for being able to retain a healthy mature street tree. When it comes to materials immediately around the base of the tree there are many alternatives available. Some of these are explored in the forthcoming LTOA publication Surface materials around trees in hard landscapes. This document analyses some of the advantages and disadvantages of the most commonly used materials, including topsoil, organic mulch, inorganic mulch, self-binding gravel, resin-bound gravel and bound rubber crumb. The conclusion – spoiler alert – is that there is no tree pit panacea. No one material is suitable for all situations. So – what is the solution to the root versus footway conflict? Depending on the specific problem there will likely be several potential solutions. Removing a healthy tree is rarely one of them. The challenge, as always, is for us as an industry to continue to promote the importance of trees as a key component – the key component – of green infrastructure; to make the argument that trees are an asset as important to the urban environment as lamp columns, drains and flat footways; and to ensure that our urban forest is managed by the right people, equipped with the right resources. View full article
  11. The Arboricultural Association

    Soil: how do we get things right from the bottom up?

    Article by Ed Baker, Planner (Tree Officer), City of Cardiff Council The soil is a dark, mysterious world. Until we put a spade into it or look at it under a microscope, we can fail to appreciate its complexity and the kaleidoscope of life it supports. It then becomes ‘muck’ or ‘dirt’, to be shifted, sifted and squashed to support development. So long as we tear it up with a big metal claw and add a bit of muck to it, it will grow us big trees without complaint, won’t it? Often we are told that trees have died because they have had too little or too much water, when the real problem is soil that has been turned into a lifeless, concrete porridge, into which a pampered nursery tree has been dropped and then, to ‘help it out’, surrounded by a quagmire of compost and fertiliser! For those of us professionally involved in the care and cultivation of amenity trees, failure to get things right from the bottom up is failure full stop. Arboriculture is no different from agriculture in that it begins and ends with the soil. Many of our towns and cities are developing fast, and soils untouched by ought but a plough since the end of the last ice age face potentially catastrophic damage. Yet with careful assessment and handling, the best of these soils can be protected so that they support the growth of large trees, giving back to the soil what centuries of farming and more recent development have taken out. To ensure that the best soils are protected and re-used appropriately, they should be professionally assessed by a soil scientist in accordance with the 2009 Defra ‘Construction Code of Practice for the Sustainable Use of Soils on Construction Sites’. This results in a Soil Resource Survey (SRS) and Soil Resource Plan (SRP) that should inform landscaping specifications and construction environmental management plans. In the same way that an arboriculturist should oversee tree protection on a development site, a soil scientist should oversee soil handling, storage, amelioration and placement, in accordance with the SRP. Leaving soil handling to groundworks or geotechnical contractors alone may result in a development that satisfies engineering requirements of the soil, but may be less suitable for supporting the establishment and healthy growth of vegetation, particularly large trees. The consequence could be costly in environmental and financial terms, requiring extensive soil amelioration, soil importation and replacement of planting failures. Relying on generic soil specifications and compliance with British Standards may result in the widespread use of imported, ‘as dug’ or manufactured, ‘multi-purpose’ soils, even when existing in situ or site-won soils could be equally or more effective at supporting the proposed planting. Different vegetation types such as wildflower grassland, amenity grassland and large, root-balled trees have differing ‘performance’ requirements of the soil, and generic specifications, or those that meet the relatively broad criteria of the British Standards only, may result in poor performance or failures. Over-specification of topsoil and underspecification of subsoil are common problems with regard to tree planting, with some considering that large trees require a deep hole full of topsoil, compost and fertiliser to grow successfully. The result of this can be oxygen depletion, excessive settlement, spiralling roots and ‘sump’ conditions, so that planting holes become bogs, with the smells to go with it! Anybody who has dug trenches to expose a soil profile knows that in nature ‘topsoil’ depths typically extend no deeper than 400mm, often much less, yet it is still common to see tree pit sections showing topsoil enveloping root-balls to 600mm depth, ‘enriched’ with composts and fertiliser and surrounded by soil of unknown specification. Subsoil on the other hand is often ignored, or simply proposed for ‘ripping’, without evidence from a soil scientist that this will be necessary or effective, or a description of the methods and equipment to be used. Particularly where larger trees are being planted, subsoil with optimal qualities of aeration and drainage, including under the loading of a large root-ball, is essential to effective establishment. Ensuring that provision is made in practical and financial terms for effective subsoil handling, amelioration or importation is essential, wherever large tree planting is proposed. Cardiff Council is preparing guidance on soils and development, but this does not seem to be a widespread approach. It will be a learning process, no doubt subject to refinement over time, but the more local authorities develop this sort of guidance, and share knowledge on best practice and local success stories, the better it will be, not only for soils, but in turn for trees and people. Should you wish to discuss the draft soils and development guidance that is in preparation, please contact treeprotection@cardiff.gov.uk.
  12. The Arboricultural Association

    Soil: how do we get things right from the bottom up?

    Article by Ed Baker, Planner (Tree Officer), City of Cardiff Council The soil is a dark, mysterious world. Until we put a spade into it or look at it under a microscope, we can fail to appreciate its complexity and the kaleidoscope of life it supports. It then becomes ‘muck’ or ‘dirt’, to be shifted, sifted and squashed to support development. So long as we tear it up with a big metal claw and add a bit of muck to it, it will grow us big trees without complaint, won’t it? Often we are told that trees have died because they have had too little or too much water, when the real problem is soil that has been turned into a lifeless, concrete porridge, into which a pampered nursery tree has been dropped and then, to ‘help it out’, surrounded by a quagmire of compost and fertiliser! For those of us professionally involved in the care and cultivation of amenity trees, failure to get things right from the bottom up is failure full stop. Arboriculture is no different from agriculture in that it begins and ends with the soil. #jscode# Many of our towns and cities are developing fast, and soils untouched by ought but a plough since the end of the last ice age face potentially catastrophic damage. Yet with careful assessment and handling, the best of these soils can be protected so that they support the growth of large trees, giving back to the soil what centuries of farming and more recent development have taken out. To ensure that the best soils are protected and re-used appropriately, they should be professionally assessed by a soil scientist in accordance with the 2009 Defra ‘Construction Code of Practice for the Sustainable Use of Soils on Construction Sites’. This results in a Soil Resource Survey (SRS) and Soil Resource Plan (SRP) that should inform landscaping specifications and construction environmental management plans. In the same way that an arboriculturist should oversee tree protection on a development site, a soil scientist should oversee soil handling, storage, amelioration and placement, in accordance with the SRP. Leaving soil handling to groundworks or geotechnical contractors alone may result in a development that satisfies engineering requirements of the soil, but may be less suitable for supporting the establishment and healthy growth of vegetation, particularly large trees. The consequence could be costly in environmental and financial terms, requiring extensive soil amelioration, soil importation and replacement of planting failures. Relying on generic soil specifications and compliance with British Standards may result in the widespread use of imported, ‘as dug’ or manufactured, ‘multi-purpose’ soils, even when existing in situ or site-won soils could be equally or more effective at supporting the proposed planting. Different vegetation types such as wildflower grassland, amenity grassland and large, root-balled trees have differing ‘performance’ requirements of the soil, and generic specifications, or those that meet the relatively broad criteria of the British Standards only, may result in poor performance or failures. Over-specification of topsoil and underspecification of subsoil are common problems with regard to tree planting, with some considering that large trees require a deep hole full of topsoil, compost and fertiliser to grow successfully. The result of this can be oxygen depletion, excessive settlement, spiralling roots and ‘sump’ conditions, so that planting holes become bogs, with the smells to go with it! Anybody who has dug trenches to expose a soil profile knows that in nature ‘topsoil’ depths typically extend no deeper than 400mm, often much less, yet it is still common to see tree pit sections showing topsoil enveloping root-balls to 600mm depth, ‘enriched’ with composts and fertiliser and surrounded by soil of unknown specification. Subsoil on the other hand is often ignored, or simply proposed for ‘ripping’, without evidence from a soil scientist that this will be necessary or effective, or a description of the methods and equipment to be used. Particularly where larger trees are being planted, subsoil with optimal qualities of aeration and drainage, including under the loading of a large root-ball, is essential to effective establishment. Ensuring that provision is made in practical and financial terms for effective subsoil handling, amelioration or importation is essential, wherever large tree planting is proposed. Cardiff Council is preparing guidance on soils and development, but this does not seem to be a widespread approach. It will be a learning process, no doubt subject to refinement over time, but the more local authorities develop this sort of guidance, and share knowledge on best practice and local success stories, the better it will be, not only for soils, but in turn for trees and people. Should you wish to discuss the draft soils and development guidance that is in preparation, please contact treeprotection@cardiff.gov.uk. View full article
  13. The Arboricultural Association

    Survey Results – Health and Safety for Climbing Arborists

    By Simon Richmond The tragic deaths of arborists have recently been in our minds. Paul Kirkley’s article brings everything into sharp definition and we owe it to him, to the memory of Alex and Greg, and of course to all arborists, to take this opportunity to scrutinise possible causes of these accidents and of course to do all we can to prevent any more. In response to the coroner’s ‘Prevention of Future Deaths’ report and request for a response from the Arboricultural Association, we met with the Health and Safety Executive (HSE) and chainsaw manufacturers to consider the overall issues. Paul Kirkley’s analysis of how his son’s accident occurred and the causal factors around the issue of kickback in top-handled saws led us to realise that, while we may have our own opinions and assumptions about what our members and others in the industry may think, we had no evidence of this. So, we issued a Health and Safety Survey which was widely distributed to all AA members and many others who are not currently members. We were overwhelmed by the response to this – over 500 people replied. We asked about perceptions of safe working practice, hazards and risk, and the potential root causes of chainsaw injuries; we also asked whether physical, mechanical guarding of the chainsaw tip was seen as a useful control. The largest group of respondents were practising arborists who use top-handled chainsaws daily. When asked about the different types of accident that were most likely, the answers were well spread across the range; however, when asked what the root cause of such accidents would be, less than 5% thought kick back would be responsible, with nearly 24% citing one-handed chainsaw use and nearly 60% identifying poor work positioning. ‘Time pressures’ and ‘fatigue/loss of concentration’ were considered to be the most likely contributory factors with ‘industry/workplace culture (bravado)’ following close behind. 72% of respondents felt that the current training and certification options for climbing arborists were adequate (28% did not). Most said that they did not experience kickback regularly. There were over 300 written comments (which space does not allow me to reproduce here) to offer opinions about our industry culture, training, causal issues and improvements to chainsaw design and/or use. When asked about technological improvements to top-handled chainsaws, the most common proposals were: improved bar/chain combinations (carving bars/safety chain) safety sensor/control to prevent onehanded operation However, a large proportion of comments suggested that ‘it is not the saw that is the problem – they’re already well designed’. Just over half of the respondents had heard about chainsaw bar ‘tip guards’ and around 65% felt that their use would compromise working practice when using the saw for compound cuts (e.g. when section felling). Finally, we asked ‘Would you feel safer knowing that the saw could not kick back?’ 55% answered ‘No’. The results of the survey were presented to Paul Kirkley at AA’s offi ces on 3 April, and he agreed to write an article for the magazine, as published on the previous pages. We also sent the results to the HSE and these were presented to the HSE’s Arboriculture and Forestry Advisory Group (AFAG) committee on 16 May. The issues raised by these accidents were discussed by the broad range of expertise that is represented on the AFAG committee. There was universal appreciation of the extensive research that Mr Kirkley had contributed and each of his recommendations was considered. After a comprehensive discussion, it was agreed that the proposal for fi tting bar tip guards to top-handled saws was unlikely to be a practical solution. The suggestion, from his response to HSE, that some form of PPE for the operator’s neck area could be made available was also discussed at length. The committee doubted the practicality of this, either of it technically being able to perform to normal chainsaw protection standards, or being a sustainable solution from an operator comfort perspective. However, STIHL has offered the services of its technical research team in Germany to carry out a desk-based review, to investigate if such a PPE garment is feasible. All agreed that we need to improve the provision of emergency planning and first aid for all aerial operations. While this would not have saved Alexander Kirkley’s life, as his injury was so traumatic, there are many circumstances where a properly planned and effi ciently executed rescue and fi rst aid provision will make the difference between life and death. The conclusions of the group were that the technical advancement of saws for use in the tree has progressed rapidly over the last few years and no doubt will continue to do so; the use of better bar/chain combinations to reduce kick back should be encouraged. However, it was generally agreed that the most important contribution to improved safe working was around behavioural and management issues, including better consolidation of experience under supervision and improved work planning, taking time to secure the correct, safe work position for every cut using both hands on the saw, and maintaining communication with others on site. Contrary to some rumours, there was comprehensive agreement that the top-handled chainsaw is an essential tool for aerial tree work and there is no proposal to restrict or ban its use. The chair of AFAG is now due to write to Mr Kirkley to inform him of the committtee’s conclusions, and to the coroner who had raised the ‘Prevention of Future Deaths’ report.
  14. The Arboricultural Association

    Survey Results – Health and Safety for Climbing Arborists

    By Simon Richmond The tragic deaths of arborists have recently been in our minds. Paul Kirkley’s article brings everything into sharp definition and we owe it to him, to the memory of Alex and Greg, and of course to all arborists, to take this opportunity to scrutinise possible causes of these accidents and of course to do all we can to prevent any more. In response to the coroner’s ‘Prevention of Future Deaths’ report and request for a response from the Arboricultural Association, we met with the Health and Safety Executive (HSE) and chainsaw manufacturers to consider the overall issues. Paul Kirkley’s analysis of how his son’s accident occurred and the causal factors around the issue of kickback in top-handled saws led us to realise that, while we may have our own opinions and assumptions about what our members and others in the industry may think, we had no evidence of this. #jscode# So, we issued a Health and Safety Survey which was widely distributed to all AA members and many others who are not currently members. We were overwhelmed by the response to this – over 500 people replied. We asked about perceptions of safe working practice, hazards and risk, and the potential root causes of chainsaw injuries; we also asked whether physical, mechanical guarding of the chainsaw tip was seen as a useful control. The largest group of respondents were practising arborists who use top-handled chainsaws daily. When asked about the different types of accident that were most likely, the answers were well spread across the range; however, when asked what the root cause of such accidents would be, less than 5% thought kick back would be responsible, with nearly 24% citing one-handed chainsaw use and nearly 60% identifying poor work positioning. ‘Time pressures’ and ‘fatigue/loss of concentration’ were considered to be the most likely contributory factors with ‘industry/workplace culture (bravado)’ following close behind. 72% of respondents felt that the current training and certification options for climbing arborists were adequate (28% did not). Most said that they did not experience kickback regularly. There were over 300 written comments (which space does not allow me to reproduce here) to offer opinions about our industry culture, training, causal issues and improvements to chainsaw design and/or use. When asked about technological improvements to top-handled chainsaws, the most common proposals were: improved bar/chain combinations (carving bars/safety chain) safety sensor/control to prevent onehanded operation However, a large proportion of comments suggested that ‘it is not the saw that is the problem – they’re already well designed’. Just over half of the respondents had heard about chainsaw bar ‘tip guards’ and around 65% felt that their use would compromise working practice when using the saw for compound cuts (e.g. when section felling). Finally, we asked ‘Would you feel safer knowing that the saw could not kick back?’ 55% answered ‘No’. The results of the survey were presented to Paul Kirkley at AA’s offi ces on 3 April, and he agreed to write an article for the magazine, as published on the previous pages. We also sent the results to the HSE and these were presented to the HSE’s Arboriculture and Forestry Advisory Group (AFAG) committee on 16 May. The issues raised by these accidents were discussed by the broad range of expertise that is represented on the AFAG committee. There was universal appreciation of the extensive research that Mr Kirkley had contributed and each of his recommendations was considered. After a comprehensive discussion, it was agreed that the proposal for fi tting bar tip guards to top-handled saws was unlikely to be a practical solution. The suggestion, from his response to HSE, that some form of PPE for the operator’s neck area could be made available was also discussed at length. The committee doubted the practicality of this, either of it technically being able to perform to normal chainsaw protection standards, or being a sustainable solution from an operator comfort perspective. However, STIHL has offered the services of its technical research team in Germany to carry out a desk-based review, to investigate if such a PPE garment is feasible. All agreed that we need to improve the provision of emergency planning and first aid for all aerial operations. While this would not have saved Alexander Kirkley’s life, as his injury was so traumatic, there are many circumstances where a properly planned and effi ciently executed rescue and fi rst aid provision will make the difference between life and death. The conclusions of the group were that the technical advancement of saws for use in the tree has progressed rapidly over the last few years and no doubt will continue to do so; the use of better bar/chain combinations to reduce kick back should be encouraged. However, it was generally agreed that the most important contribution to improved safe working was around behavioural and management issues, including better consolidation of experience under supervision and improved work planning, taking time to secure the correct, safe work position for every cut using both hands on the saw, and maintaining communication with others on site. Contrary to some rumours, there was comprehensive agreement that the top-handled chainsaw is an essential tool for aerial tree work and there is no proposal to restrict or ban its use. The chair of AFAG is now due to write to Mr Kirkley to inform him of the committtee’s conclusions, and to the coroner who had raised the ‘Prevention of Future Deaths’ report. View full article

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