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The LTOA - Caring for the Capital's Trees

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.


An LTOA response to ‘Avenues of trees raise risk of air pollution’

Trees and Pollution

Research from academics at Bangor University has suggested that avenues of trees on urban streets can damage the health of pedestrians by trapping air pollutants beneath their canopy. It warns that the effect could be so bad on streets with slow-moving traffic that councils should consider chopping down trees.

The Times, Page: 20

The above was the result of an item in ‘The Conversation’ which bears very little relation to any actual state of affairs in London - click here

A photo shows an avenue of trees, looking very much like a park. Clearly no vehicles are permitted. The avenue is lined with benches. The caption says ‘a tree canopy looks nice but where is the air pollution supposed to go’. What pollution? The fact of trees cleaning the air by deposition of pollution would suggest the opposite in this case – that the presence of trees would be keeping pollution out.

As a matter of fact the negative canyon effect is well known, the benefits of tree lined streets well documented, and the presence of such tree lined canyons in our built environment fairly rare – although, to be fair, the building bonanza in London is now creating canyons irrespective of the presence of trees.  Tree Officers, in London as elsewhere, are aware of the need to take into account all aspects of what trees deliver – good and bad – and have done for years.

There is no new debate on this. The main failing of the contribution in ‘The Conversation’ is the very factor it purports to address – that of looking at one part of a highly complex equation in isolation. Tree Officers have for years dealt with the competing demand for shade and demands for light. We know that species such as the Birches may be the very best at capturing roadside particulates but may not be suitable for a host of other reasons. That Oaks and Willows produce VOCs. Willows are almost never and Oaks seldom planted in streets – but if you want rapid growth or rich bio-diversity, these are some of the trees you need.

The argument about trees trapping pollution at street level also ignores the temperature reductions gained in tree lined streets and strangely even ignores simultaneous removal of pollution by deposition – bizarrely leaving the impression that trees are responsible for pollution.

It is suggested that trees ‘are like walls or cars’ in preventing circulation of air. They are of course nothing of the sort. Almost any vegetation has some porosity and deposition on plant surfaces is known to be many times more ‘probable’ than on   manufactured surfaces - concrete, glass and car bodywork.

It’s also true that tree officers in the UK have to consider the weather. Not simply the fact that our urban climate is becoming more and more like an arid Mediterranean one at times but also that the UK is one of the windiest corners of Europe. Practitioners such as our members would dearly love to see the ‘Canyon’ studies applied to conditions in July 2015 – seemingly one of the windiest summer months for years.

It is alleged that it is the job of ‘urban planners and local authorities to ensure trees are not just planted where they look nice’.  It might be useful to recognise the fact that between 60 and 70% of our trees are in the private sector with fairly minimal governmental control – a last hint that when discussing the benefits and dis-benefits of trees its best to look at the whole picture and not focus on one little bit. After all, that’s what research is all about!

The role of the LTOA is to enhance the management of the Capital's trees & woodlands. The environmental, social, economic, health and wellbeing benefits of trees are well documented and we would like to ensure that a clearer picture is given which has been well researched and published.

We would draw your attention to a publication by the Woodland Trust and its references  - Urban Air Quality Report (April 2012) prepared by Mike Townsend of the Woodland Trust with the assistance of Dr Tom Pugh and Professor Nick Hewitt, both of Lancaster University, and Professor Rob MacKenzie of the University of Birmingham - click here

The above article is the full response given to Horticulture Week and used in their article 'Report suggests large -canopied street trees can exacerbate pollution',  21 August 2015,

Written by Dave Lofthouse on behalf of the London Tree Officers Association

Dip. Arb. (RFS) M.Arbor.A.

Arboricultural Manager, Greenspaces

London Borough of Merton


LTOA members visit Thames Chase Community Forest on 11 August 2015

LTOA members visit Thames Chase Community Forest

A dozen or so members assembled at the Thames Chase information centre for what proved to be an informative and inspiring day. In an introductory session indoors we were fortunate to have Jim Lyon, Forestry Management Director for the East of England, to give us an overview of the vision behind the creation of the park, and how it had been sustained, despite the catastrophic changes to local authority finances, through the creation of the Thames Chase Trust and with support from the Forestry Commission. This was followed by a more detailed look at the running of the park and the use made of it from Jenny Austin, the Trust Manager.

Before lunch in the café we were then taken on a short walk. What made the greatest impression here was the sheer number of visitors using the area, clearly enjoying their days out, and how the dense forestry style planting had created a new landscape on what had been an entirely open site before its restoration.

In the afternoon we were taken a little further afield to see a couple of nearby restoration projects with Yianni Andrews and Jenny Austin​, one on the edge of the built up area, and with substantial investment to increase its capacity for recreational use, and another site which was more simply and economically designed and planted. We were able to see the progress in the design of the woodland blocks, and also the impact of the degree of restoration of the land on tree growth.

It was an excellent day useful not so much for specific lessons to be taken away on the style of planting etc., but memorable for the determination of those involved to put a vision into practice, and not to allow that vision to be abandoned. It was particularly interesting to hear the thoughts of Jim Lyon, and we are indebted to his friendship with Richard Edwards that he found time for us.

Chris Neilan

Principal Officer - Trees & Landscape Strategy - Epping Forest District Council


​Resilient Woodlands: Meeting the Challenge 1 October 2015

The event in Birmingham brings together a unique line up of experts to discuss the questions which impact on all woodland owners and managers, and on everyone who loves or is involved in woodlands – what should we all be doing to ensure our woodlands are resilient to the threat of environmental change?

Full details of the conference, the speakers and how to book are attached, or go to and follow the conference links. Please circulate the attached to colleagues/members and anyone else you feel would be interested. The conference counts towards CPD for a number of organisations, and  places are limited, so book early!

RFS President Sophie Churchill and The Woodland Trust CEO, Beccy Speight will be chairing the day.

Speakers are: Resilient Landscapes - Mike Townsend, Woodland Trust; Ecological Resilience in Woodlands -  Duncan Stone, Scottish Natural Heritage; Making Woodlands Pay - Graham Taylor, Pryor and Rickett Silviculture; Resilience: a research perspective - Professor Rob MacKenzie , BIFoR; Forest Resilience and Climate Change - Jonathan Spencer, Forestry Commission; Resilience in Living Landscapes - Stephen Trotter, the Wildlife Trusts; Natural Capital - Professor  Dieter Helm, Chairman of Natural Capital Committee (by video); Marketing your Woodland: innovations in wood product markets - Jez Ralph, Timber Strategies; Are pine martens the answer to grey squirrel control? - Dr Tom Tew, Chief Executive Environment Bank and Chairman of Vincent Wildlife Trust; A Practical Guide to taking Action on Resilience - Dr Gabriel Hemery, Sylva Foundation.

​We look forward to seeing you there

Simon Lloyd                                                               Beccy Speight

Chief Executive,                                                        Chief Executive Officer

Royal Forestry Society                                              The Woodland Trust


LTOA carried out a survey of Plane trees in 2014 looking for Ceratocystis platani

On behalf of the Forestry Commission, the London Tree Officers' Association (LTOA) surveyed 2,979 London plane trees (Platanus x acerifolia) in 2014 for symptoms of C. platani. Inspections were undertaken at 53 sites across 28 London boroughs. More than half of the sites surveyed included potential hosts planted during the past 10 years, and the sites ranged in size from a minimum of 20 to, in some cases, more than 200 trees. No positive findings of C. platani were detected in any of the trees inspected.

For more information please see this link


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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. Click here to find out how to become an associate member


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