A toxic afterlife: Trees and the dead
Alex Needs
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.
After taking a circuitous route to trees, via the music industry and the dotcom boom/bust, Alex Needs has spent the last quarter-century as an arborist, tree officer and consultant. He takes a people-centred approach to tree issues, trying not to lose focus on both the positive and negative impacts trees can bring to people’s lives. When he’s not looking at trees, he’s avoiding them on his mountain bike. Sometimes unsuccessfully.
Tree equity, benefits and maintenance in Stirling
Carla Padilla Salas
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.
Carla Padilla Salas is the first woman ISA Certified Arborist in Costa Rica and a Chevening Scholar completing a master's in Environmental Management at the University of Stirling. She has worked with UN agencies on some of the country's earliest arboriculture projects and has supported local governments in developing urban forestry, including community nurseries and green infrastructure planning. She is co-author of an arboriculture guide for Costa Rica and a pollinator‑friendly plant guide. Her research in Stirling focuses on tree equity, ecosystem services and the role of maintenance in urban forestry.
Trees of the Middle East: Observations on urban ecosystems and adaptation
Mark Laurence
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.
Mark Laurence is a consulting arboriculturist (ISA and VETcert) and landscape designer, working with sustainability and ecological principles. For the past 15 years he has been consulting in the Middle East (but based in the UK) on trees in park redevelopments, palaces and commercial projects. He has carried out site surveys, led staff training on basic pruning techniques and organised tree operations on historical sites. His recent projects include designing tree-based global biomes and coppice landscapes suitable for the region. Mark was a climbing arborist during the 1980s.
Creating bat roosts in trees
Sean Shereston and Jim Mullholland
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?
Sean Shereston (Director, Arbology) is an arborist and bat ecologist who builds tools and techniques that push survey practice forward – spanning software, optics, drones and canopy access.
Jim Mullholland (Director, BATS Research & Training) is an ecologist and arborist specialising in bats and veteran trees.
Crown restoration of heavily mutilated urban trees as an alternative to replacement planting
Ioan Stetca
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.
Ioan Stetca is President of the Romanian Arboricultural Association (ARA) and the founder of REwildSCAPE – a landscape design atelier. His work sits at the intersection of deep ecological understanding and high-end landscape craftsmanship. Ioan holds degrees in forestry engineering from Transylvania University and ecology from the University of Bucharest, complemented by postgraduate studies in primeval beech forests at Wageningen University. He is also an ISA certified arborist.