• Welcome to the LTOA website

    Welcome to the LTOA website

    The London Tree Officers Association (LTOA) constitutes the professional & technical voice for London's trees & woodlands Read More
  • Become a Sponsor

    Become a Sponsor

    The LTOA relies on subscriptions from its members and sponsorship to operate. Read More


    Capital Asset Value for Amenity Trees (CAVAT). CAVAT provides a method for managing trees as public assets rather than liabilities Read More
  • How to Become a Member

    How to Become a Member

    Members can attend, for free, the the LTOA meetings which are held four times a year and cover a wide range of tree related matters. Read More
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  • Welcome to the LTOA website

    Welcome to the LTOA website

    The London Tree Officers Association (LTOA) constitutes the professional & technical voice for London's trees & woodlands Read More
  • Become a Sponsor

    Become a Sponsor

    The LTOA relies on subscriptions from its members and sponsorship to operate. Read More


    Capital Asset Value for Amenity Trees (CAVAT). CAVAT provides a method for managing trees as public assets rather than liabilities Read More
  • How to Become a Member

    How to Become a Member

    Members can attend, for free, the the LTOA meetings which are held four times a year and cover a wide range of tree related matters. Read More
  • 1
  • 2
  • 3
  • 4

The London Tree Officers Association

Welcome to the LTOA website. The London Tree Officers Association (LTOA) constitutes the professional & technical voice for London's trees & woodlands. Its aim is to enhance the management of the Capital's trees.

We hope that you find the LTOA website both interesting & informative. If you have any questions, comments or suggestions, please do not hesitate to contact us.

I write to inform you that Sweet chestnut blight, which is caused by the fungus Cryphonectria parasitica, has been confirmed in East London and there will be a press notice about this.

It is not believed that this finding is linked to the previous outbreak in the South West. Action is being taken to identify and control the disease in line with our contingency plan and in compliance with our obligations under the UK’s Protected Zone status for this disease. We are working closely with the Animal and Plant Health Agency (APHA) to carry out extensive surveillance of sweet chestnut trees in the area, working closely with local stakeholders. Further action will be taken on the basis of surveillance information and the best available scientific evidence.

I would appeal to you/your members to help us by inspecting your/their sweet chestnut trees frequently during the coming months, and to immediately report any suspicious symptoms to us using our Tree Alert tool. A symptoms factsheet and Pest Alert is available on our website to help you/your members to know what to look for when inspecting your trees.  www.forestry.gov.uk/chestnutblight

Maintaining good biosecurity can be vital in reducing the spread of the disease so anyone visiting or working on woodland sites can play a role by includes cleaning clothes, footwear, tools and machinery before moving to other locations to avoid accidentally spreading the pest further afield.

Please also reassure family, neighbours, staff and visitors that the disease poses no risk to people, pets or livestock, and it does not affect horse chestnut (conker) trees (Aesculus hipppocastanum).

In 2013, the UK introduced special requirements that importers must notify the plant health services of pending imports of sweet chestnut plants before their arrival to enable inspection. The UK is also a Protected Zone for C. parasitica, meaning that movements of sweet chestnut plants into the UK must comply with additional requirements, and are accompanied by specific plant passports eligible for the zone and confirming that they are disease free.

If you have any queries please contact me.

Craig Harrison FICFor

Forestry Commission  London Manager 

This email address is being protected from spambots. You need JavaScript enabled to view it.


07990 563001

Area 1C Nobel House, 17 Smith Square, London SW1P 3JR



This was written by John Parker, Transport for London for the Arb Magazine and is published in Issue 177, Summer 2017

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 general public and the arboricultural industry, tree officers know better than most some of the traditional complaints. Blocked light, interrupted television 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 absolutely 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.

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 before. 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.

It is worth remembering that there are several systems of calculating a monetary value for trees, such as the CAVAT method developed by the LTOA (www.ltoa.org.uk/resources/cavat). 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 also a lot of 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? The answer is that 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.

John Parker, April 2017


The acclaimed National Tree Officers Conference will return to Telford, 8 November 2017.

The outstanding inaugural event hosted more than 200 delegates from local authorities around the UK, who travelled to Telford last November. This is the only major conference dedicated to the needs of Tree Officers. More than 97% of last year’s delegates felt the content and programme met their reasons for attending this conference.

The National Tree Officers Conference is a unique gathering for professionals interested in all areas of local authority arboricultural work. This conference is crucial to tree, woodland and planning officers; provides a significant platform for future collaborations and partnerships; and offers latest research. It will demonstrate the best practice and innovation from arboricultural and urban forestry experts.

This year’s conference will focus on a range of influential topics from leading arboricultural and urban forestry professionals:

  • Planning Best Practice & Innovation
  • In-House or Out-Sourced
  • Innovation and Research
  • i-Tree Projects

This event is being organised by the London Tree Officers Association (LTOA), the Municipal Tree Officers Association (MTOA) and, the Institute of Chartered Foresters (ICF).

Last year’s delegates demonstrate, in the below quotes, the benefits and value of attending the only UK nationally dedicated Tree Officers conference.

“The National Tree Officers Conference was a fantastic event. It was brilliant to hear how much great work is being done by tree officers all over the country and to have the opportunity to share ideas and experiences with colleagues. I’m looking forward to the next one.” John Parker, Transport for London & Chair of the London Tree Officers Association (LTOA)

“A comprehensive day that linked many of the burning issues tree officers deal with daily. Excellent value!” Jim Smith MICFor, National Urban Forestry Advisor, Forestry Commission England

“A fully interactive and engaging day, excellent turn out and thought provoking day. “Matt Seabrook, Chair, Municipal Tree Officer’s Association (MTOA)

“It was a great atmosphere at the conference, bringing together Tree officers from across the country to discuss best practice in arboriculture.” Al Smith MICFor, Arboricultural Manager, London Borough of Camden

“Great to hear Tree Officers sharing innovative approaches and ideas, and responding to the challenges they face.” Craig Harrison FICFor, London Manager, Forestry Commission

“The National Tree Officer Conference 2016 promoted idea exchange and an unparalleled opportunity for tree, woodland and planning officers to showcase their excellent work, managing local authority trees and woodlands for the benefits of the communities they serve. A key part of the event is having the ability to talk and share experiences with your peers.” Andy Lederer, Development Director, Institute of Chartered Foresters 

This event is kindly sponsored by RA-Information Systems, GreenBlue Urban, Barcham Trees and Sorbus International.

Booking information is available at: www.charteredforesters.org/tree-officers-conference


This was written by Gary Meadowcroft, Tree Services Manager at London Borough of Southwark for the Arb Magazine in Issue 177, Summer 2017.

The role of a tree officer or tree manager is not well known outside our industry. Granted, those familiar with the arboricultural profession can differentiate between the roles of arborist, consultant and arboricultural officer, but for the majority of people, including services within local authorities, the responsibilities of arboricultural officers and the work we do are not well understood or publicised. When I tell people what I do for a living they look at me blankly until I expand a little, and even then I don’t think they actually get it. I also spend a lot of time speaking to people who have a voice for trees, and often they are suspicious about the local authority and its management of trees, failing to appreciate the work we do to protect the environment.

Arboricultural officers cover a range of disciplines in much the same way as consultants, with the principal arb officer/manager responsible for the management of the strategic and operational service. A key difference between these roles is the volume of trees arboricultural officers are responsible for in a small geographical area.

The arboricultural team at Southwark consists of two arboricultural officers, an ecology officer and the tree services manager (me). The borough is approximately 17 square miles and has 57,000 trees covering parks, housing, highways and footpaths. This figure does not account for trees in woodlands, and adding those to the total would see it rise exponentially. We are quite a small team for the number of trees we are responsible for, although I am sure many other local authorities are under similar pressure.

In the public eye

Managing trees in a public environment is a tough job since everything you do is in the public domain and up for scrutiny. We could liken Newton’s Third Law of Motion to the management of trees – ‘for every action there is a reaction’, but rather than motion we’re talking about emotion, and rather than equal or opposite forces, we’re talking about the opinions of the public on every decision taken by a tree officer. 

By the time we come to undertake work on a tree, we will have gone through a systematic  process of identifying the problem,  the risk, the mitigation and what we can reasonably do to retain the tree rather than lose it. But the perception is that we just turn up and fell trees.  The fact is we manage trees for the benefit of the environment, the green infrastructure, amenity, and as social and economic assets, to name just a few of the considerations, and in order to do that we manage risk. Naturally there are times when it is necessary to remove trees because other management options and risk mitigation measures are not appropriate, but again this follows a decision-making process, with felling being the last resort.


As tree officers/managers we work on a wide range of issues, including:

  • pests and disease
  • subsidence
  • hazard surveys
  • regeneration
  • development
  • arboricultural impact assessments
  • planting
  • woodland management

For all of the above, a large volume of work is undertaken by committed and passionate officers to address the problems, liaise or consult with the public and ensure that the decisions we take are the most suitable for the benefit of the trees and the public.  We use a range of sophisticated tools to assess the health of trees such as decay detection devices including the Picus Sonic Tomograph 6/12, PD series resistograph and motion sway sensors.

We also have a Cabinet Approved Strategy and are members of the London Tree Officers Association (for which I sit on the executive committee, the Biosecurity Working Group and the Canker Stain of Plane Working Group). As an organisation of tree officers and consultants we produce a range of documents for tree professionals to aid them in delivering tree management within their boroughs, something which could be better advertised in the public domain (see John Parker’s article on trees and footways, page 53). The general public is often not aware that we are working for the benefit of protecting the environment and trees, and that a lot of officer time is committed to producing such documents.

Working on the big picture

I recently met with a group of people about contentious trees in one of our parks. I had taken the decision to remove some trees on the grounds of safety as they were in poor condition and located on the edge of a footpath with a high foot and bicycle traffic fall. Following the assessment of the trees and careful consideration (including options for retention), I decided removal was the best approach and site notices were erected to inform the public. What followed was a string of emails and requests for a site meeting so that I could explain my decision. But if the role of the tree officer was better known then there would have been a sense of comfort that we are working to protect the environment. Removal of trees often creates opportunity for replanting to create a sustainable landscape with an uneven age tree mix that gets away from monoculture and enhances diversity, thus providing more resilience and longevity. During the meeting it was intimated that what I was actually doing was destroying the amenity of the area by removing mature trees and replacing them with young trees. However a mature landscape started life as a young landscape. It was hard work convincing them otherwise and they couldn’t see the risk I could see, regardless of the explanation. This, I think, sums up the general experience of tree officers as there isn’t the information or exposure to our jobs as tree specialists.

Some of the work we do can play a big part in the wider issue of tree management and the health of trees across the UK and beyond. Take canker stain of plane for example (CSP): this pathogen poses a  threat to the planes of the UK if it reaches our shores, and based on what we know, this is most likely to happen from infected tools being brought back in to the country by arborists working abroad. I work as part of a team headed up by John Parker in London to monitor the pathogen. This work is important not only to protect the trees but also to provide important data to the Forestry Commission on potential sightings. So our work extends outside of the borough.

I was lucky enough last year to attend the first international workshop on CSP in Padua, Italy, organised by Treework Environmental Practice and Lucio Montecchio (see ARB Magazine 175, pages 64–69). This study tour provided invaluable information for the detection of CSP which I and others have since brought back with us to implement within our boroughs. This was an opportunity for tree officers and tree consultants to work together for the benefit of trees in the British Isles and is another facet of our work that generally goes unnoticed.

Promote the profession

Frustratingly, people seem to notice our work when a tree is removed or pollarded – and certainly in Southwark when the tree is linked to a case of property damage. The public perception will be that we have undertaken work which appears drastic and, in the residents’ eyes, unwarranted. So, what’s the answer to this? Consult? Notify? As a responsible authority we will notify and consult through different mechanisms including a Tree Management Strategy, which clearly sets out our aims and objectives, but this doesn’t always help because of the suspicion that we are overzealous in removing or pollarding trees as a precaution to avoid financial risk and property damage. The reality is we are very thorough when assessing a claim to ensure the right management approach has been implemented for an implicated tree. 

We need to better promote our profession and be seen as the advocates for trees and the environment that we are. Perhaps these days social media is an obvious platform because it is instant, accessible and often gets shared, ‘liked’ or ‘re-tweeted’ to name a few, and I think a good mechanism for starters is the communications team within a local authority who can promote the good work being done. After all, we are managing vast numbers of trees and making complex decisions whilst maintaining best urban forest practice and working with a diverse range of clients.

I think as an industry we can do more by building on the positive reaction by tree officers to the 2016 National Tree Officers’ Conference, working with national bodies like the Arboricultural Association and the Institute of Chartered Foresters, promoting the role of arb officers as the professional group who manage the largest urban forests in the UK and just as importantly, promoting collaboration with other organisations at a local and central government level.


National Tree Officers Conference 2017

The National Tree Officers Conference will be held on 8 November 2017 in Telford, Shropshire with speakers sharing their experience and best practice within Local Authority Arboriculture. Anyone is able to attend and booking information is available here.

The LTOA website is sponsored by:

How to Become a Member

Members can attend, for free, the LTOA meetings which are held four times a year and cover a wide range of tree related matters.

Click here to find out how to become an associate member