Abstract

1. Attempts to address biodiversity loss have led to ecosystem and species restoration efforts. Tree species restoration is particularly relevant because of increasing threats from pests and pathogens. However, there are different notions of ‘loss’, as well as sociocultural considerations, including social acceptability, which are often neglected in decision-making for restoration.

2. This paper explores concepts and meanings of ‘loss’, discusses sociocultural aspects and analyses social acceptability in relation to possible restoration routes for elm species in Great Britain (GB).

3. We identified different forms of ecological or species ‘loss’. For this paper, we recognise the following: Biological loss relates to biological extinction at varying scales. Functional loss refers to functional characteristics and traits of a species. Cultural loss refers to cultural connection, and societal loss refers to common utilisation and values.

4. Tree species such as field elm and wych elm have either radically transformed or have almost disappeared from large areas of GB since the 1960s, due to Dutch Elm Disease (DED). Biological presence continues, mainly in the form of small shrub-like trees, but functional, cultural and social loss continues through the decline of most large, freestanding elms. Some mature elms remain in refuge areas, especially in the north of Scotland where DED has not yet been recorded.

5. A range of restoration routes have been identified for elm in GB, from individual tree management or the creation of biosecure refugia, to the use of genetic technology. These options are each subject to different constraints, address ‘loss’ in diverse ways and face different levels of social acceptability, related in part to sociocultural connections.

6. We conclude that the following must be addressed to ensure socially acceptable routes to restoration: recognition of sociocultural considerations, trade-offs between public engagement and efficacy, absence of trust, lack of accessible information, evidence gaps, long-term funding and resources, and platforms for public dialogue. We emphasise the need for multiple notions of ‘loss’ and a shift to consideration of interlinked social, cultural and ecological regeneration as we forge new relationships and practices for tree health and sustainability.

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Abstract

The United Kingdom aims to dramatically accelerate the establishment of new woodlands by 2050, yet the impact of different afforestation strategies on landscape genetic diversity and resilience remains unclear. This study integrates environmental data, whole-genome sequencing and phenotypic assessments to compare bioclimatic envelopes, genetic diversity and plant health indicators in naturally colonised versus planted populations of pedunculate oak and silver birch.

We found that registered seed stands significantly under-represent the wild bioclimatic envelopes of both species, as well as those of 21 out of 39 UK native species assessed, potentially limiting adaptive diversity in planted populations. Yet, genetic diversity metrics (π, H_O and A_R) based on genome-wide markers in planted populations were comparable to naturally colonised woodlands. Planted populations exhibited higher within-group coancestry and moderate genetic homogenisation among sites, possibly reducing adaptive differentiation.

Naturally colonised populations showed higher inbreeding coefficients (F_ROH) in both species, potentially due to fragmentation of source populations. Genotype–environment associations based on redundancy analysis revealed divergent selection at functionally relevant loci, indicating distinct selective pressures in commercial tree production versus natural colonisation. Health indicators revealed reduced browsing in planted trees, and differences in mildew and leaf-spot incidence, suggesting potential selection divergence between afforestation strategies.

These findings support a role for both afforestation strategies in enhancing the resilience of future woodlands while highlighting pathway-specific risks of introducing unintended impacts on forest diversity.

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Abstract

Rapid evolution via small shifts in allele frequencies at thousands of loci are a long- standing neo-Darwinian prediction but are hard to characterize in the wild. European ash tree (Fraxinus excelsior) populations have recently come under strong selection by the invasive fungal pathogen Hymenoscyphus fraxineus.

Using genomic prediction models based on field trial phenotypes and 7,985 loci, we show a shift in genomically estimated breeding values in an ancient woodland, between adult trees established before the epidemic started and juvenile trees established since.

Using simulations, we estimate that natural selection has eliminated 31% of the juvenile population. Thus, we document a highly polygenic heritable micro-evolutionary adaptive change over a single generation in the wild.

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Trees and other woodland plants are species that have economic, environmental, scientific or societal value. Plant species have traits that can be passed on to their offspring, and the reproductive materials that produces the next generation of plants that are considered of value is known as ‘forest genetic resources’. These materials can be seeds and propagules, tissue cultures, living plants or DNA samples.

In our pilot year, one of the projects developed a national report on the State of Forest Genetic Resources in the United Kingdom which was published by Defra. The report is part of a global effort to capture the State of the World’s Forest Genetic Resources. It covers a definition of which species are considered to be UK forest genetic resources, and which are at risk. A section on conservation looks at ‘gene-conservation units’ within natural woodlands, and conservation through seed banking and living clone collections. Two further sections examine the use, development and management of resources, and the policies, stakeholders, leadership and capacity to protect and research these resources.

The main recommendation of the report is that a strategic approach in which conservation, use, management and development of FGR are brought under a clearly defined framework.

Further information on forest genetic resources can be found on the UK Forest Genetic Resources website >>

Kew Research Repository

The Royal Botanic Gardens, Kew research repository is an open access repository for the research produced by staff and research associates of RBG Kew. The repository currently houses material such as journal articles, conference papers, books and book chapters, reports, datasets and images.

Access the repository >>

Forest Research Publications Catalogue

Find out about the wide range of information to support sustainable forest management in Britain. The catalogue includes the Forestry Commission’s publication library and archive, as well as Forest Research articles and guidance.

Access the catalogue >>

Genetic diversity is crucial if the UK’s forests are to thrive, as it increases the likelihood that some trees will have will have the built-in resilience to pathogens and stressors (like drought). This can then be passed on to future generations.

In this first research publication of the CFP, scientists from Royal Botanic Gardens, Kew, and Forest Research, present a detailed analysis of the genetic diversity and comparative tree health of young British woodlands, revealing the pros and cons of planting versus natural colonisation.

Throughout their CFP project “Evaluating genetic and environmental bottlenecks in planted and naturally colonised woodlands”, Kew and Forest Research scientists looked at sites with naturally colonising and planted English oak and silver birch to compare young tree condition and assess the small differences in DNA between tree populations.

Headline findings showed that a combination of both planted and naturally colonised new woodlands is likely to be best for maintaining genetic diversity.

Read the full Policy and Practice Briefing >>

In spring 2025, we ran a series of webinars to showcase the results from some of our phase 1 research projects. Researchers from Forest Research, Royal Botanic Gardens, Kew and collaborators presented their work on elms, predisposition to disease, how trees adapt, comparisons of diversity between planted and naturally colonised new woodlands, and genetic methods to improve conifer resilience.

You can view the webinars and each of the individual talks here: CFP Spring 2025 webinar series and on our YouTube channel.

Alongside our researchers, our 2024/25 cohort of interns each gave a short talk about their projects, which you can view here: CFP Intern Talks.

Ash dieback is a highly destructive disease of ash trees, especially the European ash, one of the UK’s most common woodland trees. Caused by an invasive fungus (Hymenoscyphus fraxineus), ash dieback is predicted to cost the UK £7.6 billion by 2030.

The aim of this project was to uncover the genetic basis of resistance to ash dieback, which can be used to inform potential ash breeding programmes and, ultimately, assist the long-term survival of native ash populations.

Read the full Ash Genomics Pilot Summary Report >>

Find out more about this pilot project >>

British forestry is highly reliant upon non-native tree species such as Sitka spruce and Douglas-fir which originate from western North America. However, non-native trees may be at risk from native pests and diseases, the threats of which can be intensified by climate change. There is, therefore, an urgent need to develop approaches for identifying potential new threats, to inform new tree planting schemes and ensure future forest health.

This project aimed to develop an innovative, data-driven horizon scanning framework for identifying threats to key tree species growing in Britain. The approach could also be extended to other species, including native British species growing in other parts of the world.

Read the full Horizon Scanning Pilot Summary Report >>

Find out more about this pilot project >>

Acute oak decline (AOD) is a complex disease affecting thousands of UK oak trees, many of which die every year. The aim of this study was to identify genetic factors contributing to AOD susceptibility in UK oak populations, which is crucial for developing effective strategies to mitigate the impacts of this devastating disease.

Read the full Oak Genome Pilot Summary Report >>

UK woodlands need to adapt to a warming climate, which may disrupt existing patterns of local adaptation.  We need to make careful choices about the sources of seeds in order to plant resilient woodlands. To do this, we need to understand the genetic basis of adaptation within tree species.

The aim of this project was to identify genetic variations in collections of UK birch and alder seeds that are associated with possible adaptations to different local environments.

Read the full UKNTSP Pilot Summary Report >>

Find out more about the pilot project >>

Centre for Forest Protection projects have contributed to RBG Kew’s ash genome resource with an improved version of the reference genome for European ash and a reference genome from a low-susceptibility tree. You can find information about Kew’s ash genome projects on The British Ash Tree Genome Project website.

Links to all of Kew’s ash resources can be found on the ash community on Zenodo.

You can also find more information about these resources in our blogs and news pages.

Read the blog: European Ash – how an improved reference genome can help our research >>

News items: A new reference genome from a healthy ash tree >>

The Centre for Forest Protection projects have included whole genome sequencing. The raw sequenced data are publicly available as follows:

Ash (Fraxinus excelsior) raw genome sequences on ENA Browser, Project PRJEB44697 >>

Oak (Quercus robur and Q. petraea) genome sequences on NCBI, Project PRJNA816149 >>

Oak (Quercus robur and Q. petraea) genome sequences on ENA Browser, Project PRJEB43909 >>  (funded by Defra Future Proofing Plant Health).

Oak (Quercus robur and Q. petraea) genome sequences on ENA Browser, Project PRJEB30573 >> (funded by Action Oak).

Birch (Betula pubescens, B. pendula, B. nana.) and Alder (Alnus glutinosa) on NCBI, Project PRJNA825844 >>

Ash dieback map

View UK areas where ash dieback has been confirmed to be affecting ash trees in the natural environment.

Browse the map >>

Forest Research Open Data

Download a wide range of Forest Research and Forestry Commission spatial datasets for use in Geographic Information Systems (GIS). Map layers available for either England, Scotland, Wales or all of Great Britain, include surveys of tree pests and diseases.

Visit the Forestry Commission’s Open Data website >>

Kew data and digital resources

Explore Kew’s data, tools and resources for a wide range of plant and fungal information.

Browse Kew’s data and digital resources >>

Kew Data Portal >>

The Forest Research website has a wealth of information >>

Forest Research pest and disease information >>

Tree Alert – for reporting tree health concerns >>

The Climate Change Hub brings together information and practical guidance about protecting our UK woodlands and forests from the impacts and risks due to the changing climate through adaptive practice.

Forest Research Publications Catalogue

Find out about the wide range of information to support sustainable forest management in Britain. The catalogue includes the Forestry Commission’s publication library and archive, as well as Forest Research articles and guidance.

Access the catalogue >>

Kew has extensive collections and digital resources, including a data portal with free access to millions of specimens.

Collections and resources | Kew >>

Kew Data Portal >>

Kew Research Repository

The Royal Botanic Gardens, Kew research repository is an open access repository for the research produced by staff and research associates of RBG Kew. The repository currently houses material such as journal articles, conference papers, books and book chapters, reports, datasets and images.

Access the repository >>

The Observatree project provides a range of free field identification guides, host of the month information sheets, guides, pest & disease resources, posters, training videos and webinars from the Observatree citizen science project. Working with the UK Plant Health Risk Group, Observatree has identified the pests and diseases that are of the highest concern to the UK.

Observatree resource library >>

Browse priority pests and diseases >>

Browse pests and diseases by tree species >>

The Yorkshire Arboretum comprises more than 7,000 trees from around the world and is also home to The Tree Health Centre, an initiative aiming to make people more aware of the importance of a healthy treescape, and the problems caused by tree pests and diseases. The Tree Health Centre Resource Hub has been created to help make the wealth of tree health and biosecurity information across the internet more easily accessible.

Tree Health Centre Resource Hub >>

The following organisations have useful information about careers in Forestry and Forestry Science:

Careers | Forestry England >>

Careers in Forestry – Royal Forestry Society >>

Routes into forestry careers – GOV.UK >>

Find a career in forestry: resources and guidance – GOV.UK >>

Careers in entomology – Royal Entomological Society >>

Careers and Educational Courses – BSPP – The British Society for Plant Pathology >>

Employers that often recruit plant scientists >>

You can access our free Professional and Technical Training modules, along with training and resources from other organisations across the sector, via the Institute for Chartered Foresters (ICF) online learning platform Silvestor:

Welcome to the Centre for Forest Protection | Silvestor >>

You can access a list of the key terms used across our website here:

Glossary & Key Terms – Centre for Forest Protection >>