Tree Health Forum reflects on winter
Storms were significant...
The Tree Health Operations Forum, convened by Defra and The Tree Council, consists of a panel of tree health experts from government, research bodies, local authorities and charities. The meetings cover seasonal challenges affecting tree health and establishment, operating as a knowledge-sharing platform for those in tree health related roles. It invites open discussion from Forum members on what is working well for them ‘on the ground’ and what challenges they are facing.
Read on to find out more about the issues highlighted in this Winter Tree Health Operations Forum update…
Winter 2025/26 tree health snapshot
The Met Office providing an insight into the UK’s recent weather, with winter so far (December 2025 - February 2026) particularly stormy and wet. Four named storms impacted the UK over the season. Cornwall provisionally recorded its wettest January on record with 267.6mm of rainfall, as did County Down with 230.1mm. A strengthened jet stream, influenced by cold weather in the US and pushed further south than normal bringing a continuous series of storms and rain systems. These were then stalled over the country due to a block of cold air in Scandinavia.
This caused prolonged periods of rain across much of the country. Looking ahead into spring, the UK can expect close to normal conditions for the season. In general, spring in the UK has been warming over recent decades while trends in temperature and sunshine are also showing increases although this is less pronounced. Observations suggest that extreme weather events are becoming more common in the UK, heightening the risk of physical damage to trees (from both storms and droughts) which can increase their susceptibility to pests and diseases. With warmer temperatures moving further north and to higher altitudes, we may also see the northward movement of biomes and therefore habitats.
Cornwall County Council then provided a first-hand account of its experience of the winter weather, highlighting the impact of Storm Goretti in January 2026 on its treescape. The storm was recorded as one of the strongest experienced in Cornwall, with gusts of over 80mph causing severe impacts to people and infrastructure. There was also a huge amount of damage caused to (and by) trees, including:
1,238 urgent tree safety issues and more than 1,000 tree failures across Cornwall’s highways network
More than 200 urgent and non-urgent tree safety issues in public open spaces, including damage to burial grounds, roads, footpaths, walls and other infrastructure.
Loss of significant trees by other major landowners such as the National Trust, with 80% of canopy on St Michaels Mount lost.
This extreme weather event highlighted the need for the development of a formal ‘extreme weather response protocol’ to better support local authority preparedness in future. This should include details of high risk areas, with consideration of appropriate proactive and reactive management interventions to increase the storm resilience of a county’s trees.
National Highways outlined how it manages trees along the strategic road network, and on its soft estate (195,503,286 m2 of grassland, rock and scree, scrub, march and wetland and woodland). Tree pests and diseases are a growing concern, with Sooty bark disease (Cryptostroma corticale) increasingly reported in the South West and North West, while Phytophthora ramorum continues to affect larch, sweet chestnut and rhododendron. Ash dieback (Hymenoscyphus fraxineus) also poses a particular challenge, with over 121,000 trees recorded in its ‘critical’ category of assessment. National Highways stressed the need for a comprehensive vegetation management plan, as existing highway contracts do not commonly incorporate plans for vegetation management, which makes the restoration and retrofitting of older roads challenging.
Moving from roads to rail, Network Rail updated the Forum on tree management across its estate. The rail estate currently covers 52,000ha and includes 13 million trees within falling distance of the railway or overhead power lines. With 1/3 of the population living within 500m of the railway, tree-related incidents pose significant safety and operational risks across the network, but a lack of data on tree failures makes preparedness challenging. During storm events or other extreme weather, recording data (like the species of tree that has failed) does not occur as the priority is clearing the line quickly and safely. This makes it difficult to predict which locations and species to target with increased inspections.
Our Winter 25/26 Forum concluded with a presentation from DEFRA, who sharing its tree health policy update. Defra noted the continued slow spread of oak processionary moth, ongoing eradication work through the OPM management programme, and a review of long-term OPM policy. The monitoring programme for Ips typographus (eight-toothed European spruce bark beetle) continues, with 2025 outbreaks quickly contained and now all undergoing eradication action. DEFRA highlighted its expanded grants programme now supporting both spruce removal and site assessments in high risk areas.
A new sweet chestnut blight (Cryphonectria parasitica) outbreak in Devon was also reported, prompting intensified monitoring and a call for increased reporting. DEFRA discussed its work towards introducing hypovirulence as a form of biological control on sweet chestnut blight within the UK.
Looking ahead: supplementing the tree data gap
Four key themes emerged from the ensuing discussion:
Should local authorities, land managers and others in the industry develop shared guidance on an extreme weather response specifically in regard to trees?
Is there a need for funding or support to improve storm resilience of tree assets particularly in vulnerable areas?
What data would be useful to collect to support an evidence-based, strategic response to extreme weather events?
How do we create resilient treescapes?
Many of the trees deemed safe by prior inspections had subsequently failed during Storm Goretti, highlighting a significant knowledge gap when considering what trees are likely to fail and why. Those in ‘on the ground’ roles discussed how operational pressures, especially during emergency response situations (which often occur at night), mean that teams prioritise clearance over recording of data.
The Forum felt that collecting more detailed data following tree failure (e.g., species, failure type, any evidence of pests or disease infection) would allow tree managers to infer:
Whether tree species influences the likelihood of tree failure
The impact of tree location on the risk of tree failure
Whether existing pest or disease infection had an impact on failure
It could also allow tree managers to identify trees that suffered storm damage. Recording damaged trees could highlight those more vulnerable to tree pests and disease infection, or future failure, and allow more targeted monitoring.
A coordinated approach between land managers, local authorities and central government, using technology such as remote sensing, could allow data collection on canopy change over time. Identifying whether trees have been removed as a planned response due to a risk assessment, landowner choice or because of storm damage would also allow for greater understanding of treescape change and help to target future inspections or management.
Despite the differences between the organisations present (in capacity, resource, organisational type etc), the inadequacy of current asset management systems for recording and managing extreme weather events, particularly with regard to tree species and condition data, was echoed across the Forum. Standardising the methodology for data collection on the impact of extreme weather on trees would allow the development of a comprehensive dataset, thus allowing land managers to make informed, strategic decisions when managing their treescape.
Resilient treescapes
Storm resilience also emerged as an area of concern amongst members. The group expressed a need for guidance addressing:
Species selection for more resilient trees in the face of increasingly erratic weather
The use of structural management techniques such as pollarding to make existing trees less vulnerable to extreme weather
Designing resilient landscapes that can better withstand storm impacts
There were also calls for additional funding and support to be made available for tree management and planning in high-risk areas.
Practical resources for planning, resilience and adaptation
Discover a range of online tools and information about climate change risks to UK woodlands and guidance for practitioners on adaptation through Forest Research’s Climate Change Hub
To support species planting choice, take a look at the Climate Matching Tool
The Resilience Implementation Framework has been designed to provide a structured way to implement resilience for trees, woodlands and forests.
Get in touch and share your experience with the Forum
Are you a land or tree manager? We are seeking best practice asset management (in relation to tree damage e.g., when they die or are blown over) to share with the Forum. If you have, or are aware of examples to share, please do get in touch.
If not, tell us what type of data or information would help you manage the impact of storms and other extreme weather on trees in your area.
Please contact us by emailing scienceandresearch@treecouncil.org.uk.
For guidance around tree establishment, monitoring and survival, as well as pests and diseases and seasonal advice, please visit The Tree Council’s Guidance Hub.
Katie Jones is The Tree Council’s Science & Action Research Officer
Find out more about The Tree Council at treecouncil.org.uk. Sign up to our monthly newsletter The Leaflet, and follow our social accounts: Instagram, TikTok, Facebook, LinkedIn, X/Twitter, YouTube.
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