Conference Speakers 2026

Abstract

Reading tree architecture in formative pruning: Identifying future scaffold limbs in young trees

Formative pruning is often approached as a practical operation aimed at creating clearance, correcting defects and guiding young trees towards a functional urban form. However, young trees do not all build their crowns in the same way. Their architectural development determines which branches are temporary, which axes remain subordinated, and which branches may later become permanent scaffold limbs.

This presentation links the principles of the European Tree Pruning Standard to a practical morphological reading of young trees. Using the three growth models described in the standard, the presentation explores how different tree species organise their main axis, lateral branches and temporary or persistent forks during early development.

The central question is: which branches are likely to become future scaffold limbs, especially at an undesirable height within the clearance profile? By recognising these potential low scaffold limbs early, arborists can make better decisions about timing, pruning intensity and branch removal. This is particularly important in species where temporary codominance or plagiotropic (more or less horizontal) growth can be misread as a structural defect, leading to unnecessary or poorly timed pruning.

The aim is not to replace existing pruning standards, but to make them more practical by connecting them to tree architecture and developmental stage. Formative pruning should not only shape a tree for its surroundings; it should guide the tree through its natural architectural development with minimal disruption.

Abstract

Morphophysiological pruning – adult/mature trees

Morphophysiology is a diagnostic tool derived from the study of tree architecture; it serves both descriptive and practical purposes. Through this approach, the qualitative organisation (the form) of a tree provides information on its behaviour, both physiological and, where applicable, pathological.

As the form is a dynamic, consequential and coherent phenomenon, studying the tree allows us to deduce and understand its past and predict its future, both naturally and in relation to necessary arboricultural interventions.

This is particularly useful in the case of morphophysiologically adult or mature trees, as it enables their management to be planned on a multi-year, even long-term, scale, defining the types of pruning – in both qualitative and quantitative terms – that are most appropriate in each instance.

Furthermore, morphophysiological analysis enables the organisation of the crown to be correlated with that of the trunk and the root system, making this visual approach extremely effective when integrated with a more strictly biomechanical analysis.

Abstract

Structural root adaptations in an ancient holotype Chiranthodendron pentadactylon

In Toluca, Mexico, stands a remarkable specimen of Chiranthodendron pentadactylon (macpalxóchitl or Mexican hand-flower tree) estimated to be over 300 years old. This tree is historically significant, having been studied by Alexander von Humboldt, and it represents the holotype by which the species was originally described.

In recent years, the tree has experienced a decline in vitality due to water stress, adverse environmental conditions and extreme spatial restriction within a densely confined urban setting. Age-related degradation, combined with site-specific mechanical constraints, has significantly compromised its biomechanical stability.

Management interventions by the Mexican Association of Arboriculture and the Municipality of Toluca have included pruning and the installation of structural supports. However, sonic tomography identified a critical loss of structural integrity at the base of the trunk, indicating that the tree is no longer self-supporting. A non-invasive morphophysiological assessment was conducted to investigate internal adaptive responses. The findings suggest the development of a concealed adaptive strategy within the organism, challenging conventional interpretations of structural support in senescent trees.

This presentation will examine these structures through the framework of root wood. The findings will be discussed in relation to contemporary models of tree architecture and morphophysiology, highlighting the adaptive capacity of ageing trees under extreme urban constraints

Abstract

Cauterizing pruning cuts and tree wounds: Traditional stewardship in modern arboriculture

Indigenous cultures worldwide have used fire as a tool in forest and tree management for millennia. This presentation will explore the application of fire as a tree care technique to naturally accelerate the Compartmentalisation of Decay in Trees (CODIT) process within fire-adapted Quercus species.

Sprout’s study implements traditional practices through the controlled application of fire using a handheld blowtorch to cauterise pruning cuts and injuries. Thermal cauterisation has demonstrated significant benefits, including the reduction of microorganism and fungal colonisation, improved wound closure and accelerated response wood development at the reaction zone. By blackening but not charring key tissue layers, including the phloem and cambium, burning pruning cuts stimulated the specialised cells in the branch collar, promoting rapid wound closure. Cauterised wounds exhibited significant callus formation, achieving full closure within 2–3 years, depending on soil health and tree vitality. In contrast, untreated wounds exhibited minimal response growth and a substantially higher susceptibility to fungal colonisation.

These findings highlight thermal cauterisation as a sustainable, chemical-free alternative for managing tree wounds, particularly in fire-adapted ecosystems.

By integrating Indigenous cultural practices with modern arboricultural research, this approach offers an innovative solution for mitigating pathogens, enhancing tree health and reinforcing the ecological resilience of fire-prone landscapes.

Abstract

Crown restoration of heavily mutilated urban trees as an alternative to replacement planting

Urban tree populations across Europe are increasingly characterised by mature specimens subjected to repeated severe pruning, topping and crown mutilation. These interventions profoundly disrupt tree architecture and morphophysiological balance, frequently leading to structural dysfunction, decay development and progressive vitality loss. Consequently, many heavily altered trees are routinely removed and replaced. However, replacement planting cannot reproduce, within meaningful human timescales, the ecological and climatic functions delivered by mature urban trees.

In this presentation Ioan will explore crown restoration as an alternative management strategy for heavily mutilated urban trees, with particular emphasis on biodiversity conservation and long-term urban resilience. Using a morphophysiological approach, he will examine how topping suppresses apical dominance, disrupts hormonal equilibrium and triggers the production of traumatic reiterations that progressively form unstable crown systems. At the same time, many of the structural transformations generated through severe pruning – including cavities, decay columns, exposed heartwood and irregular crown architecture – can create highly valuable habitats for saproxylic insects, fungi, birds, bats and other specialised organisms. In fragmented urban ecosystems, such trees may continue to function as important biodiversity reservoirs despite their altered condition.

The presentation will further examine practical restoration strategies based on the work of Pierre Raimbault, for selective management of traumatic reiterations. Through gradual intervention cycles that maintain physiological stability while progressively reducing structural risk, heavily damaged trees can often be guided toward new, functional crown architectures.

Drawing on field-based case studies from recent restoration projects, this presentation will argue for a shift from reactive removal practices towards informed arboricultural management that balances safety requirements with ecological continuity, habitat preservation and the long-term ecosystem services provided by mature urban trees.

Abstract

Creating bat roosts in trees

Fourteen of the UK's 18 bat species live in trees, with some species spending all year in them. Due to their complex ecology, a colony of tree-roosting bats may use up to 50 trees across the year. However, tree habitats don't last forever; trees or their features eventually fall. The longevity of tree-dwelling bats therefore requires a constant supply of new roost sites.

Historically, options for tree roost mitigation have been limited to bat boxes and habitat translocation. However, these are short-term fixes and not without limitations.

Can targeted damage to trees provide an alternative solution to this problem?

Abstract

Trees of the Middle East: Observations on urban ecosystems and adaptation

The modern Middle East combines rapid urban growth with extreme climate conditions. Despite this, landscapes flourish through heavy use of TSE (treated sewerage water) and imported subtropical species. This approach has been used since the 1970s, and many created landscapes are now mature. However, horticulture is rarely recognised as a discipline, arboriculture is only emerging, and maintenance practices remain largely traditional and often inappropriate.

Climate change is intensifying heat, storms and heavy rainfall, with summer temperatures in the UAE often exceeding 50°C. Trees grown with irrigation and limited root space are therefore prone to windthrow and damage, but culturing the landscape as an urban ecosystem could enhance resilience.

Mark’s observations draw on 15 years spent working as an arboricultural consultant in the region, including visits to brownfield sites where many introduced species, left unmanaged, are forming novel (or hybrid) ecosystems without irrigation or intervention. Native trees are often absent from these sites, while many so-called ‘invasive’ ornamental species thrive. Their success suggests a new model for unirrigated, resilient landscapes that function as adapted ecosystems – providing shade, urban heat mitigation, stormwater retention, living soils and even urban productive systems for food or coppicing for mulch production.

Recognising trees as keystone elements of the urban ecosystem – and adopting ecological arboriculture – will play a crucial role in fostering a transformation to environmentally attuned, climate adapted and people-friendly landscapes.

Abstract

Tree equity, benefits and maintenance in Stirling

Trees provide shade, help manage stormwater and make neighbourhoods more liveable. However, not all communities benefit equally. This study compares neighbourhoods with high and low Tree Equity Scores in Stirling, Scotland. The aim is to move beyond tree counting and instead examine two aspects: the ecosystem services trees actually deliver, and how they are maintained.

The research focuses first on quantifying three services: carbon sequestration, pollution reduction and avoided runoff. Second, it assesses visible maintenance – pruning, untreated wounds and watering – across the same neighbourhoods. The question is whether maintenance is proactive (regular pruning and care) or reactive (only when roots lift a pavement or a branch becomes hazardous).

This study does not assume that planting more trees automatically solves inequity. Instead, the aim is to understand if a cycle exists where neighbourhoods with fewer resources also receive less proactive care, leading to trees that do not thrive and residents who receive fewer benefits.

Abstract

A toxic afterlife: Trees and the dead

Diverse cultures have long embraced a natural return to the elements through practices like sky burials, shroud burials and sacred groves. Today’s modern ‘green burial’ movement seeks to revive these nature-connected traditions. However, the human desire to rest beneath a beautiful, mature tree poses a hidden conflict, as conventional interment practices can severely damage or kill the very canopy people wish to preserve.

Modern conventional burials introduce toxic embalming fluids and non-biodegradable coffins into critical tree root zones. Meanwhile, cremation ashes, often viewed as eco-friendly, have an extreme pH and sodium levels higher than plants can tolerate, blocking essential nutrients. To bridge the gap between honouring traditions and protecting tree health, this presentation explores historical, soil-beneficial practices alongside some practical arboricultural solutions.

Abstract

How can we predict future pest and disease risks to trees?

Human activity has caused the global movement of species and brought many trees into contact with novel pests and diseases – both through the accidental introduction of harmful organisms into new areas and as a result of trees being planted outside their native distributions. This can lead to significant tree health issues in cases where tree species are not already adapted to cope with these threats – recent striking examples include the devastating ash dieback epidemic in Europe, and the impact of the invasive emerald ash borer in both Europe and North America.

Consequently, many efforts are ongoing to predict which pest and disease threats are most likely to materialise so actions can be taken to try to prevent them. One way of predicting which of the millions of potential interactions between trees and harmful organisms are most likely to occur is by using information on evolutionary relationships between hosts. Pests and pathogens are more likely to spread onto new hosts that are more closely related to their existing hosts – this evolutionary signal has been shown to be a powerful predictor of the likelihood of a pest or pathogen jumping onto a new host.

Laura will describe the development of modelling approaches that make use of the evolutionary signal in pest and pathogen host range to predict which new, potentially harmful, interactions are most likely to occur, focusing on risks to global oak species and to lesser-known species of interest for UK tree planting. These predictions could be used to: 1) prioritise tree pests and pathogens for further action to mitigate risks; and 2) guide choice of tree species for resilient future plantings.

Abstract

Assessing pest and pathogen risks to the urban forest

Urban trees provide a wide range of ecosystem services, including climate regulation, air quality improvement, biodiversity support and benefits to human wellbeing. However, these benefits are increasingly threatened by the introduction and spread of invasive pests and pathogens. Despite growing concerns over tree health, there has been limited assessment of the specific risks posed to England’s urban forest.

This presentation will outline the development and application of a quantitative pest risk matrix designed to assess the threat posed by quarantine pests to the urban forest. The approach combined data on urban tree composition, pest likelihood of introduction and establishment, potential host impacts and tree prevalence to generate risk scores for individual host–pest interactions. In total, 1,666 host–pest interactions were assessed across the 50 most common urban tree genera in England.

The risk matrix identified 154 quarantine pests capable of affecting common urban tree hosts and highlighted a relatively small number of pests responsible for a disproportionately high share of overall risk. The analysis also identified the tree genera and species most vulnerable to future pest incursions and highlighted areas of significant uncertainty where further research is required.

The presentation will discuss how risk-based approaches can help prioritise surveillance, biosecurity measures and contingency planning within urban environments.

Abstract

Canker stain of plane: An update on research to prepare for an outbreak

Forest Research, represented by Mick Biddle, will give an update on research aimed at strengthening the UK’s preparedness for the damaging disease canker stain of plane (CSP), which is caused by the fungal pathogen Ceratocystis platani.

Recent outputs and ongoing activities include:

• Research to optimise surveillance and enhance the capability to provide rapid diagnostics of suspect sample material.
• Preliminary evidence on the socio-cultural value of plane trees, their distribution within the UK, and the knowledge needs of land managers regarding CSP to better understand and communicate about the resource at stake.
• An investigation into disease introduction pathways via used arboricultural and civil engineering equipment, and the experience of CSP experts managing the disease in Europe to inform effective UK contingency planning.
• Current research modelling the influence of urban networks on the spread and management of CSP.

Abstract

LIFE CoolCity project: AI and remote sensing for evidence-based urban forestry

Urban forests are key elements of urban climate adaptation, addressing impacts such as urban heat islands, extreme rainfall and increasing thermal stress. However, they are also affected by climate change, and their effective management is often hindered by fragmented data and a lack of integrated spatial analyses.

During the workshop, Aleksandra will introduce a multi-scale framework developed within the LifeCoolCity project (since 2023, in partnership with Wrocław City Hall; co-financed by the EU LIFE programme), demonstrating how integrating satellite imagery, high-resolution hyperspectral aerial data and LiDAR – processed using machine learning – can transform raw geodata into practical tools for arboriculture.

The methodology focuses on five key components shaping a city’s adaptive capacity: surface sealing, thermal conditions, hydrological conditions, vegetation condition and biodiversity. In Wrocław, the outputs include a range of spatial products, among them a detailed crown canopy map and biodiversity map for consistent assessment of the city’s vegetation structure, distribution and condition. The system extracts detailed measurements for each tree, including canopy area and volume, estimated trunk diameter, height and classification across 52 classes. Furthermore, the crown health map allows managers to assess crown vigour and hydration levels remotely.

The framework provides a decision support system that identifies ‘hotspots’ – priority areas where interventions, such as planting or enhanced maintenance, can deliver the greatest cooling and hydrological benefits. This will enable data-driven prioritisation of care, including targeted mulching or watering of trees under stress.

Such an approach should empower urban managers to shift from reactive maintenance to evidence-based, strategic management, ensuring that both urban forests and individual trees are optimised to meet the urgent challenges posed by climate change.

Workshop participants will have a chance to test different CoolCity products on their own laptops, compare their potential, as well as limitations, and discuss them.

Abstract

Survival strategies of ancient and veteran trees: Morphophysiological life stage 10

Trees have evolved to cope with the forces of nature – high winds, storms, drought, lightning strikes, gravity – in a variety of different ways. We’ve all seen trees that have broken apart, partially collapsed, lay down or even disintegrated and yet retained a functional, living section which keeps the tree alive. These remarkable examples and the process of ‘tree reorganisation’ can be described and understood using the language of tree morphophysiology.

The morphophysiological life stage model includes stage 10 – 'reconstruction of the tree'. Very few trees ever achieve this but those that do illustrate the varying processes by which trees can persist.

In this presentation Russell and James will describe various stage 10 survival strategies, with examples of how different tree species may tend to favour one strategy or another. This is likely to be useful for anyone considering the condition and management of ancient and other veteran trees (AoVTs), the most ecologically valuable trees any of us will ever deal with.

Nature doesn’t necessarily fit into neat categories but learning the language of crown architecture and morphophysiology provides us with vocabulary and concepts to describe what we observe, allowing us to share that information to build understanding of these remarkable trees. Join Russell and James on a fascinating journey into stage 10 and beyond!

Abstract

Tree preservation order work applications: Getting it right

Each local planning authority manages hundreds of tree preservation order (TPO) work applications every year, and nationally 400–600 of those go to appeal. Appeals take time and tend not to be successful. In Jonathan’s workshop, we will look at how applicants and agents can make their TPO work applications effective, defensible, more likely to be successful and more likely to succeed at appeal.

We will examine what TPOs are for, and why applications might be made, and follow that through to the components of effective applications. Focussing on appeals will allow us to work back to making the application in the first place – and to see if it is possible to avoid appeals by improving applications. We will also explore the role of tree officers and what might influence their decisions, and what constitutes best practice for local planning authorities and applicants. We will look at real cases and provide guidance on applications, with workshop discussions throughout.

Abstract

Regenerating soil systems around tree roots

Low-quality rooting environments are consistently associated with tree decline and poor health. Nutritional depletion of soils and high levels of soil compaction act to reduce the quality of the rooting environment and suppress tree performance. Arborists have been able to deploy techniques such as pneumatic soil cultivation, radial trenching, soil injection and vertical mulching for some time. However, there has not been a formal framework around the training for these activities.

This practical demonstration is designed to give delegates an insight into the new Lantra-accredited ‘Regenerating Soil Systems Around Tree Roots’ – a two-day course that is specifically designed to train arborists in the knowledge and techniques required to enhance the rooting environment around tree roots.

It is anticipated that this new course will address the training deficit in this critical area. The course is the outcome of an ongoing collaboration between University Centre Myerscough (UK) and Soil Mania (NL).

The demonstration will focus on pneumatic and hydraulic techniques to enhance the condition of mature trees experiencing stress through the regeneration of the soil system. In addition to aiding tree health, adopting these techniques within an arboricultural contracting portfolio can add value to your business whilst improving your company's resilience and reputation.

Please do come along and learn more.

Abstract

Into the MycoVerse: 3D modelling and the future

Understanding how trees and fungi interact is central to arboricultural decision-making, yet many important species are difficult to study, identify or revisit in the field once fruiting bodies have passed their best. This workshop will explores how 3D scanning could help create accessible, interactive fungal resources for arborists, educators and future field guides.

Using MycoVerse as a case study, we will look at the practical opportunities and challenges of building a reliable 3D fungal reference library, capturing usable scans in the field, confirming accurate identifications, hosting models sustainably, linking digital resources to printed field guides and developing a collaborative network of 3D scan contributors.

The session will invite discussion on how we can all work together to document important fungi before they disappear from sight.