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  1. 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.
  2. 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
  3. 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.
  4. 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
  5. 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.
  6. 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
  7. 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.
  8. 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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