Taking action to protect Sorbus trees
The latest update to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species published in July 2026 has brought renewed attention to some of the UK and Ireland’s rarest native trees: the whitebeams, rowans and service trees of the genus Sorbus.
Westonbirt, The National Arboretum is helping bring together experts and conservation partners to improve understanding of these remarkable species and inform action to protect them.
A unique, endangered group of UK trees
The UK and Ireland are home to just 42 species of Sorbus found nowhere else in the world.
In 2016, almost all UK and Irish Sorbus species were assessed as threatened with extinction.
Many occur in just one single valley, gorge, cliff face or small woodland area, and because their populations are often very small this makes them especially vulnerable to habitat loss, disease, environmental change and poor natural regeneration.
Careful management and long-term monitoring will be essential for their future survival.
Bringing experts together
In December 2025, Westonbirt Arboretum and Botanic Gardens Conservation International (BGCI) organised a specialist workshop as part of the Global Tree Assessment. This brought experts from across the UK together to share data, review evidence and reassess the conservation status of UK Sorbus species.
Participants included representatives from Natural England, the Royal Botanic Garden Edinburgh, the National Botanic Garden of Wales and Sorbus experts.
This collaborative approach is vital. For rare and highly localised trees, accurate conservation assessments depend on detailed field knowledge, recent survey information and specialist taxonomic expertise.
What the latest Red List update reveals
While many Sorbus species remain in the same Red List categories, the updated assessments provide more up to date population counts and reveal some significant changes:
- Devon whitebeam (Sorbus devoniensis) has been reassessed as Near Threatened, having previously been listed as Vulnerable. This change is the result of surveys locating more individuals, giving a clearer and more encouraging picture of the species’ population.
- Wilmott’s whitebeam (Sorbus wilmottiana) is now considered Critically Endangered, having previously been assessed as Endangered. The species is known from a very small number of remaining individuals and has been affected by an unknown pathogen, as well as impacts linked to railway upgrades in the Avon Gorge.
- Two species described since the previous assessment – Faye’s whitebeam (Sorbus fayana) and Wye whitebeam (Sorbus wyensis) – have also now been assessed for the first time. Both are classified as Critically Endangered.
Significant findings like this underline just how fragile the future of some UK Sorbus species remains.
Turning assessment into action
Red List assessments are essential conservation planning tools, helping to identify which species are most at risk and where action is most urgently needed. The updated Sorbus assessments have provided the chance to reassess their conservation status and the action needed to secure their future.
They support the work of the Global Conservation Consortium for Whitebeams, Rowans and Service Trees, launched in 2024 and led by Forestry England at Westonbirt, The National Arboretum.
The consortium brings together institutions and experts to develop and deliver conservation strategies for Sorbus species across their global range. Its work combines in situ conservation, protecting trees in their natural habitats, with ex situ conservation, including living collections, seed banking and propagation.
Understanding the gaps
Alongside the Red List reassessments, the consortium and the BGCI have recently published the first conservation Gap Analysis for threatened whitebeams, rowans and service trees in the UK and Ireland, which can be viewed here.
For a group of trees as rare and localised as Sorbus, this kind of evidence is crucial. This analysis looks at how well these species are currently represented in living collections and seed banks, identifies key threats and reviews existing conservation action. It also sets out priorities to guide future work, ensuring the conservation effort is coordinated, strategic and focused where it can make the greatest difference.
See pictured: Westonbirt Arboretum’s Tree Conservation Manager, Rosie Anderson examining Sorbus anglica seedling in the Cheddar Gorge during gap analysis survey.
Safeguarding these trees for the future
The updated IUCN Red List assessments are a reminder of the extraordinary tree diversity found in the UK and Ireland, and the responsibility we share to protect it.
The reassessment of UK Sorbus species is an important step forward. The next challenge is to turn that knowledge into lasting conservation action through the continued consortium work.
We are grateful to the Friends of Westonbirt Arboretum for their continued support for our tree conservation work.
You can also play a part. Your generous donations will have a crucial role in supporting this conservation work.