Conference Speakers 2023

Biography

Andrew Benson is a practicing consultant arborist in Auckland, New Zealand. He has a particular interest in how trees interact with urban environments and has a research background that focusses on integrating trees with urban sites and human activity as harmoniously as possible.

Abstract

Urban trees play an important role in human society, by providing a range of ecosystem service benefits. Ecosystem services are defined as the direct and indirect contributions of ecosystems to human wellbeing, for example, carbon sequestration, pollutant adsorption, and stormwater runoff interception. The amounts of these so-called ‘regulating services’ are positively correlated to leaf area, and so large trees with large total leaf areas will produce greater benefits. However, it is common for urban trees to be pruned to meet modern requirements set by the electricity generation provider, wherein branches are removed to achieve statutory clearances between trees and the overhead utility wires, to prevent outages and faults in the electrical network. This sort of pruning can remove considerable proportions of live foliage.

Using iTree Eco, this research investigated whether utility wire pruning affected ecosystem service benefits for three regulating services (carbon sequestration, pollutant adsorption, and runoff interception). The 25 most common urban street trees in Auckland, New Zealand, were ascertained by examining a record of 10,323 tree records held in our database. A further 15 trees selected by Auckland Council’s urban forest manager were added to the list making a total of 40 urban trees. Mean mature dimensions (trunk diameter at 1.4 m, height, and crown spread) and standard deviations were ascertained for each species and 100 representative trees for each species were simulated with a normal distribution for each dimension in each species. Trees were stratified into small, medium, and large trees, being trees with a mean mature height of < 5 m, 5 m-10 m, and > 10 m, respectively. Two simulated utility wire pruning treatments were then established, being an L-shaped treatment, and a topped treatment, where an elliptical segment was removed from the latter, and half the elliptical segment was removed from the former. The percentage loss of crown volume for each tree was computed based on the two pruning treatments and the data were entered into iTree Eco for analysis of ecosystem services.

Utility wire pruning significantly reduced ecosystem service provision in large trees at p ≤ 0.05, but not in small or medium trees. Large trees that had been topped ($26.68) had significantly fewer total annual benefits than control ($46.11) and L-shaped trees ($36.97). The effect of tree size on ecosystem services was significant for all treatments. Large control trees had significantly greater ecosystem services than small control trees for all ecosystem services. Large control trees had significantly greater ecosystem services than small and medium trees for all ecosystem services. The differences in ecosystem service provision between trees in different size classes and between different treatments can be explained by differences in leaf area. Interestingly, large, topped trees still had significantly greater total ecosystem service benefits than small unpruned control trees. Local communities can still receive greater ecosystem service benefits by planting large trees that require ongoing utility wire pruning at maturity, than from small trees that do not.

Biography

Benoit has 12 years’ experience as an arborist and has worked in Europe, Vancouver, Hawaii, Melbourne and, of course, France. He is self-employed as a consultant and also runs training in arboriculture.

He says, ‘I work with a modern approach to arboriculture, based on clinical diagnosis and methodical tree risk management, with the aim of better preserving our tree heritage. I provide support for tree management decisions, adjusting my advice and recommendations in line with an ecosystem approach, favouring the environment and ecosystems through a methodological and reasonable approach to risk.’

Benoit specialises in bracing, providing solutions and training in the installation, management and control of bracing systems.

Abstract

Bracing and cabling systems are two solutions to prevent or consolidate a tree or one of its parts. The objectives are to protect the surrounding potential target, reducing the associated risks, and maintain the integrity of a tree.

However, cabling and bracing systems require regular checks and the management of these inspections for releasing or replacing old systems can be complex.

This has become particularly problematic since the 1990s with the introduction of the well-named ‘non-invasive’ systems, which appeared easy to install and less expensive than the ‘old systems’.

After years of practice and reflection, we will be presenting our developments in cabling, using measuring tools and modern mixed systems integrating drilling techniques with newer materials.

The different bracing systems are compared and critiqued, in order to understand their strengths and limitations, and to raise the possibilities for further development.

Biography

Kristin is a consulting arborist at COWI A/S and a part-time teacher at a technical college in Norway. She has been in the arboriculture industry for about 20 years and is often out on building and infrastructure construction sites ensuring that the correct procedures are followed to protect existing trees. She also collaborates with architects and landscape architects to find good solutions for preserving trees. Over the last two years, she has dedicated herself to studying tree roots.

Abstract

Construction works and existing trees are a common and complex combination. The responsibility for overseeing the protection and wellbeing of trees on a site often falls to arborists. When it comes to trunks and crowns, methods of species identification and assessment are plentiful and well known, but this has not been the case for tree roots. The aim of our project has been to create a field guide for arborists to aid the identification of roots. My colleagues and I are often on site to ensure that the correct procedures are followed to protect existing trees. When digging works reveal tree roots, it is not always obvious which tree the roots belong to. Roots can expand far beyond a tree’s crown, and they are covered in soil and dirt. This recurring challenge – and our professional responsibility to save trees – inspired me and my colleague Olve Lundetræ to study more closely the roots we came across during our work. We began to assess roots more systematically as they appeared in trenches and on building sites. As a result, we learned that roots of different species are almost as different as their branches and leaves. We found roots with beautiful colours, amazing patterns, strange bark and different structures, and some with a distinct smell. So far, we have identified roots from around 40 different tree species. Our field guide includes descriptions and photographs of the roots. We hope that this information will help other arborists on site, and perhaps give them the evidence they need to change the direction of a trench or get a planned building moved by a few metres.

Biography

Greg Packman is an Arboricultural Officer for The Royal Parks in London and specialises in the management of Massaria Disease of Plane. Having worked with Massaria, Greg has undertaken in the region of 90,000 ground-based Massaria inspections, developing an expertise in the identification, understanding and management of the fungus.

Greg’s work with Massaria has seen him deliver presentations on Massaria to audiences in the UK, America and Europe; Greg has also written a series of publications, presentations and workshops on Massaria.

Abstract

Massaria disease of plane has been a recognised management consideration in London since 2008; with more urban areas across the country having to recognise Massaria as part of their ongoing tree management as it develops and emerges.

While the identification symptoms have been more widely understood and publicised, the biology and implications upon tree health are not widely known while misunderstanding remains around the ways in which to manage the disease.

This presentation will cover the known biology of Massaria: how the fungus is understood to work; how it capitalises on stressed branches; the trees’ natural defences to inhibit Massaria and how environmental conditions and change can enable Massaria development.

We will also explore aspects of Massaria management, such as the legal duty of care and how Massaria factors into this. The defensibility of ground-based surveys; the survey process, timing and frequency of inspections, and wider management decisions at a population level that Massaria may impact.

Biography

Richard Hauer is the Director of Urban Forestry at CNUC and a Professor of Urban Forestry at the University of Wisconsin – Stevens Point teaching courses in urban forestry, nursery management, and woody plants. He received Ph.D. from the University of Minnesota. Rich conducts research in tree biology, urban forest management, emerald ash borer management, trees and construction, and tree risk management. He was honored as the 2018 L.C. Chadwick Award for Arboricultural Research. He has published over 190 publications and presented over 480 talks throughout the world. Dr. Hauer is also an Associate Editor for Urban Forestry & Urban Greenspaces.

Abstract

Planning for emerald ash borer (EAB) is a first and important step rather than dwelling in the EAB financial blues. Since EAB is on your doorstep in the UK, this talk will set out what we have learned to date with emerald ash borer management in North America. Since it was discovered in 2002 in North America, several ways to manage the insect have been developed that are both effective and economically efficient. Urban forestry management approaches for EAB management include economic analysis, treatment, tree risk assessment, and other strategies to shift the blues back to keeping the green in your urban forest. Learn how to estimate the costs and net benefits associated with pre-emptive removal, post-mortem removal, and treatments. Learn the implications of long-term tree injections and how ash trees respond to wounding. We will present studies using external wounding and internal discolouration associated with wounding with tree injection.

This talk will also further present the financial impact of emerald ash borer on municipal forestry budgets. Our research team was the first to test the net present value of EAB management options.

We also discovered three distinct phases were evident: an initial time period of 0 to 4 years (little budget change), years 5 to 8 time period (rapid budget increase), and years 9 to 12 (rapid budget decrease) after EAB was confirmed. Financial impacts on budgets will be set out and the effects on urban forestry activity (removal, pruning, education, safety training, tree planting) budgets further discussed. Research we conducted from the City of Milwaukee and the loss of ecological values of tree populations will be conveyed. Ultimately, the audience will learn how to plan now to make the impact of EAB on tree populations as painless as possible.

Biography

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Abstract

Using examples, I will explore problems with the management of Meripilus on beech, the premature felling of valuable trees, what happens when we prune them, root and soil biomechanics, root adaptations according to load, diagnostic methods, wind-load analysis and whole-tree stability assessment based on data.

I will also discuss the ceramic root problem and some other takes on that, the possibility of exaptation rather than weakness by looking at decay profiles of roots, and strength loss, including what that actually means in the direction of load.

All the large beech trees we have inspected over the last 25 years that are known to have Meripilus have had no increased risk of failure … and they haven’t failed even in hurricane winds.

Intervention may make things worse, and careful inspection rather than knee-jerk responses would save many more trees. Many of the trees that have been felled did not have serious decay and those that were pruned were ultimately felled later because decay progressed more rapidly after crown a reduction.

Biography

Elizabeth is called as a barrister in England and Wales and the Supreme Court of the Eastern Caribbean (British Virgin Islands). She has a legal practice in chancery, commercial, business and property, including Local Government work. She offers specialist advice in arboricultural law and forestry, including property damage, nuisance and enforcement matters. She represents a wide range of local authorities, individuals and insurers and is regularly instructed to advise on issues relating to highways, land, rural, environment and the Town and Country Planning Acts. Elizabeth is also a sought after Mediator and Arbitrator, being a commercial mediator and arbitrator (MCIArb and Fellow and Director of FICA, ICCA). Elizabeth is a skilful mediator and advocates the use of mediation in settling disputes at an early stage. Elizabeth became a barrister after a career in commercial, including working for SCA, the consumer products and forestry company. She has experience in FSC, sustainability and the commercial issues relating to paper and forestry products.

Abstract

Elizabeth will speak about what is biodiversity net gain? What are the requirements? Who does it affect? And what (if any) are the legal implications for non-compliance?

Biography

Emilie has worked in the environmental sector for approaching 20 years, spending the last 18 of those with the Green Action Trust. Since becoming Operations Director in December 2021, Emilie has led the Trusts Strategy and Development team with overall responsibility for the major Green Infrastructure initiatives currently being developed and delivered by the Trust.

These include the Central Scotland Green Network, Europes’ largest green infrastructure programme; and the 10,000 Raingardens for Scotland programme, a national initiative to increase the use of nature-based climate solutions.

Abstract

The Central Scotland Green Network is a National Development in the lately adopted Scottish National Planning Framework 4. It was initially conceived in 2010, and had environmental action at its heart, aiming to deliver social and economic benefits through environmental regeneration.

This presentation will set out the drivers behind the idea of the CSGN, and its development from the only “green” initiative within Scottish Governments Planning Policy into a major National Development delivering a step change in environmental quality on the ground in areas of real need.

We will cover the outputs, outcomes and benefits of the CSGN, how it is delivering and both the landscape and the local scale, discuss some of the challenges and successes, and look at some exemplar projects from recent years.

Biography

Paul is a forest pathologist, urban forester and remote sensing scientist. He is the Director of Innovation & Technology at Arborflight Ltd. UK, Managing Director of ArborCarbon, and Adjunct Professor at Murdoch University. Paul has been a board member at the not-for-profit Trillion Trees (formerly Men of the Trees WA) since 2014. He has been very fortunate to undertake projects on most continents and he is very passionate about providing land managers with accurate data to make informed decisions for sustainable management of landscapes and cities.

Abstract

Biodiversity Net Gain (BNG) is a concept that seeks measurable improvements to biodiversity with delivery of a mandatory 10% BNG to be maintained for a period of 30 years. The metrics focus only on habitat with some key attributes, including the size, condition, and connectivity. Methods for measuring BNG can be very resource intensive, expensive, time consuming, and open to interpretation/error depending on the expertise of the assessor(s). This presents a key challenge to managers and stakeholders with access to limited personnel, resources and funding.

Very high-resolution, airborne, remote sensing tools have the capacity to provide BNG metrics across space and time in an affordable, rapid, efficient, accurate and repeatable manner, across the entire country. Satellite data can scale but has many limitations around spatial resolution and lack of accurate height data, with vertical structure a critical attribute for biodiverse habitats. Unmanned aerial vehicles and drones can provide the spatial resolution and accurate height data, but are limited in their scalability and are resource intensive. We will present examples where airborne remote sensing data has been combined with artificial intelligence to accurately measure not only the size, condition and connectivity of habitats, but also delineate individual trees, benchmark their size and condition, and identify and discriminate species of tree and shrub for classification of habitats according to their diversity and distinctiveness, other key factors for measuring BNG.

Biography

For the last 15 years, Lee Mueller has worked to achieve balance at the intersection of vibrant communities and healthy environments. Lee has served as staff, board member, or volunteer for a variety of community initiatives dedicated to parks, forestry, and environmental causes. He is a Certified Arborist and Certified Forester, with forestry degrees from Michigan State University. He’s a Market Manager with Davey Resource Group, Inc. and lives in Grand Rapids, Michigan, United States.

Abstract

Data-driven decision making and the need for accurate, up-to-date tree information is holding back the urban forestry industry from tackling hard social and environmental issues like tree equity, climate change, and resilience. One of the greatest impediments for city foresters and planners with regard to creating and updating street tree inventories is the cost and time it takes to conduct a comprehensive inventory of public trees. Moreover, as biological assets, trees change and inventories become outdated within a short period of time.

Technologies used in the monitoring of urban trees are rapidly changing. Simple applications of aerial and ground-based imagery (e.g. google, bing), as well as robust machine-learning approaches are opening the way for City Foresters and Planners to quickly and accurately map public trees and potentially identify species, assess health, and collect biometrics. With these new approaches, urban foresters are afforded more options for the assessment of their trees than ever before. Further, machine-learning screening tools may help arborists and foresters identify tree issues that require additional investigation, better prioritizing their time spent in the field.

While these technologies are new, they are rapidly advancing. The performance of initial tree assessments from a desktop computer may be a reality, sooner than we think. While technology is unlikely to replace arborists anytime soon, arborists who use advancements in technology are likely to outpace those who don’t. The presentation will discuss emerging approaches in tree assessment and machine learning at the community level. The data that can currently be collected, limitations, costs, and additional opportunities will be explored.

Biography

Martin started his career in arboriculture at Forest Research (part of the Forestry Commission) before working for two years at the Arboricultural Advisory and Information Service. He launched his own arboricultural consultancy in 1997. Over the last 25 years he has prepared hundreds of expert reports where trees are involved in litigation, particularly on tree-related subsidence and tree failure cases. He has appeared as an expert witness in some notable court cases including, most recently, the matter of Hoyle v Hampshire County Council and others. Martin has wide experience in delivering lectures and training on tree safety, and subsidence.

Abstract

This presentation will consider recent court cases where trees have failed and look behind the scenes at the role of a tree expert in the legal process where a claim for injury or damage has been made against the tree owner – from examining a fallen tree, to cross-examination and legal judgments.

For many, the role of an ‘expert witness’ is shrouded in mystery, but Martin will lift the lid on the process of gathering data, forming an opinion, being challenged by a barrister, preparation of a joint statement with the opponent’s expert, and cross-examination in court. He will then set out some of the legal principles that have been determined by the courts in tree-failure judgments and consider a number of recent cases (including Hoyle v Hampshire County Council and others), offering an opinion on what they tell us about the law (and published guidance), and how they might influence attitudes to tree-safety inspections and liability

Biography

For at least thirty years, I have had a specialist interest in ancient and other veteran trees and ancient Forests, wood pastures and parkland. This interest has led me into understanding the history and structure of past landscapes through ancient trees. I am a qualified VetCert Consultant. I am a keen surveyor and verifier for the Ancient Tree Inventory , a project hosted by the Woodland Trust in partnership with the Tree Register of the British Isles and the Ancient Tree Forum. I am a Trustee of the Forest of Selwood and the Tree Register of the British Isles.

Abstract

Trees of National Special Interest are those which – because of their age, size, condition, associated species, rarity, heritage or cultural value as individuals or collections of trees – have qualities of such significance that they differentiate them from most trees of the same species. Some trees are particularly valuable because they have multiple national values, e.g. King John’s Oak – a very large-girthed, open-crowned, ancient oak with a unique historic name which is host to at least one extremely rare decay fungus.

Across Europe there are interesting distributions of autochthonous species of ancient trees such as yews, oaks and beech. The distribution of such tree species, and especially old-growth remnants at the limit of their range, gives us insights into the way changing conditions across the continent are affecting their associated biodiversity and their adaptation to changing climate. This information should help us in assessing the risks to our current trees and what we should do in the future.

The UK has a long history of famous plant hunters who over several centuries have brought back tree and shrub species from across the world. Many trees have been introduced since the 16th century and the oldest ones are now up to 400 years old. Some of these are closely related by genus to other indigenous species but others are completely different. In some cases trees in the UK are perhaps the last remaining specimens of species that are under extinction threat in their home ranges. How such trees adapt to the conditions in the British Isles gives us insights into their tolerance to entirely different circumstances and how they may provide useful alternatives to our native trees if they cannot adapt to the changes that are forecast.

All of our Trees of National Special Interest have lived lives which should be of great interest to arboriculture and society.

Biography

Jason holds a degree in arboriculture from Paul Smiths University in New York State, USA, and has been a “life-long” arborist for the last 25 years. During his career Jason has worked as an arborist at The Morris Arboretum University of Pennsylvania; climber and foreman for commercial tree care companies in both the UK & USA; a local authority Arboricultural Officer in Surrey and Dorset; as well as a private arboricultural consultant before rejoining Bartlett Tree Experts in 2014. Since being promoted to Principal Consultant, as well as delivering and managing a consultancy service in Bristol, Jason oversees the daily operations as well as overall business direction and growth of Bartlett Consulting within the larger Bartlett Tree Experts UK & Ireland Division.

Abstract

The Allerton Oak is a veteran tree, estimated to have stood within the landscape of Calderstones Park, Liverpool since the 1400’s. A series of steel props were installed circa 1960 to prevent failure of the tree due separation of the stem into multiple functional units as well as the presence of wood decay.

However, as time passed, many of the props themselves entered into a state of failure and redundancy, putting the Allerton Oak at risk once again. Commencing in 2019, a multidisciplinary team of professionals led by Bartlett Tree Experts designed and installed a new set of props to replace and reinforce the old steel props, aimed at preventing bio-mechanical failure of the Allerton Oak and maintaining it within the landscape for decades to come.

This presentation will take the delegates on a journey through the various process and stages of the project including: team meetings; data collection and analysis; prop design iterations; soil sampling; vitality testing; soil amelioration; prop installation; and monitoring following installation – sharing what we learned, what we achieved, and what can still be accomplished through this project with the wider arboricultural profession (as well as relevant external parties) for future use.

Biography

Emma is a plant/ fungal ecologist. With a PhD from Cardiff University, she has contributed to research on wood decay and tree hollowing, veteranisation and saproxylic insect ecology. In her current role, Emma provides specialist ecological advice, guidance and training. She also works in a range of external partnerships to drive the conservation of ancient and veteran trees.

Abstract

Ancient and veteran trees are irreplaceable structures of exceptional value for nature and people. And they have many secrets to reveal.

These trees can appear to be stalwarts in the environment – old, resilient or unchanging – in fact, they are easily lost. There seems to be a decline in the number of ancient and veteran trees in the UK and globally, as their conservation needs are often overlooked or not understood.

I am interested in scientific storytelling and developing evidence-informed policy and practice. In this talk, I will share some science that excites me. Join me to hear about recent research and preliminary results from Woodland Trust-funded studies.

Biography

Dr Kate Lewthwaite studied plant ecology at the University of Durham.

She has been at the Woodland Trust for 20 years, promoting the public understanding of, and engagement with, environmental science.

She is citizen science manager and currently oversees three long-term citizen science projects.

Abstract

Nature’s Calendar is the Woodland Trust’s longest running citizen science scheme and potentially the UK’s longest written biological record, dating back to 1736.

Trees and shrubs make up about half of the species recorded. Volunteers are asked to note annual phenological events such as the dates of budburst, first leaf, flowering and leaf fall.

When combined with meteorological records these provide a compelling story of how our trees, shrubs and wildlife are responding to climate change.

Biography

Cat Walker is Impact Manager at Trees of Cities. She oversees the monitoring and evaluation of the charity’s projects.

Abstract

Much of the research on the social benefits of trees tends to focus on people passively engaging with trees, such as using green spaces which contain trees (Turner-Skoff, 2019), rather than the effect of actually participating in tree-planting (Watkins et al., 2018). However, what research there is shows that active involvement in tree-planting is linked to higher satisfaction with trees being planted, reduced desire for trees to be removed and a greater appreciation of the impact of trees on the local area (Sommer et al., 1994). Furthermore, community involvement in greening more broadly helps people learn new skills, build relationships with neighbours and empower people to feel they can make a difference (Ohmer et al., 2009). The government has also identified community involvement in tree-planting in the England Trees Action Plan 2021-24 (DEFRA, 2021) as an important way of connecting people to nature. Trees for Cities' delivery model is centred around local communities and has evolved over thirty years of the charity’s existence. This approach involves community mapping, community outreach - introducing the project, community consultation – sharing the initial design, event planning and delivery, and the use of the site by community members. Trees for Cities has robust monitoring and evaluation processes in place to help us understand who we are engaging and the impact our work has on community members. Drawing on survey responses from the 2021/22 planting season, we have found three core findings:

1. Our community events engage local people - we found that the majority (64%) of people attending planting events are local to the site, having travelled 30 minutes or less to get there (n = 298).
2. Most community volunteers already value urban trees and are highly connected to nature - community members scored highly on a scale asking them to rate the importance of urban trees as well as the Nature Connection Index (NCI). On average, community volunteers had a score of 74 out of 100 before the event (n = 674), rising to 77 out of 100 after the event (n = 461). This baseline score is already higher than the mean adult NCI score of 61.16 set out by Richardson et al. in 2019.
3. Most people volunteering at our planting events have had no previous experience - 74% of 896 volunteers surveyed had no previous experience in planting or looking after urban trees before attending our events.

These findings demonstrate that there is a role to play not only in inspiring new individuals but also to build the confidence, knowledge and skills of those already interested in trees and nature, in the areas where they live. Trees for Cities' new community engagement strategy draws on these learnings, aiming to both inspire and enable groups and individuals to plant and protect trees. We have plans to build co-design and more in-depth consultations into more of our projects. We are also looking at how we can make our events as inclusive as possible, in a collaboration with the Sensory Trust.

Biography

Jim is an ecologist and arboriculturist, with particular interests in veteran trees and bats. He conducts research and dissemination of findings. His current research focuses on measures to improve how trees are surveyed for bats.

He runs his own research and training company, BATS Research and Training, and is a senior bat conservation officer for the Vincent Wildlife Trust.

Abstract

Surveying trees

In 2017, Jim spoke at conference on the topic of surveying trees for bats. Posing the question ‘Can we do better?’ he shared the results of his research, including details of the types of trees used by bats and the difficulties of finding bat roosts in trees.

Continued research, utilising trail camera technology, has sought to overcome the low encounter rate of standard bat surveys. Jim will share findings from his ongoing research: Can trail cameras give us the advantage we need? What information can we glean from these cameras? And who would win in a fight between a noctule and a grey squirrel? For the answer to these questions, and many more, come along and find out.

Creating bat roosts in trees

14 of the UK’s 17 bat species are known to roost in trees. Whilst some species demonstrate a degree of flexibility, others are entirely reliant on trees. The bat species which are tree-roosting specialists are some of the rarest.

Mitigation measures for these tree-roosting bats are limited to bat boxes. However, these boxes provide sub-optimal conditions and don’t work for all species. Building on existing veteranisation research, Jim will share an update on his work seeking to create bat roosts in living trees.