Promoting resilience of UK tree species to novel pests and pathogens: ecological and evolutionary solutions

It has been made clear by examples such as Ash Dieback, that our trees face a serious threat from new diseases and pests. As trees are everywhere and are well-loved parts of our landscape, an important part of our economy and an essential part of our biodiversity, their loss has serious consequences. However, dealing with each new threat as it comes along is difficult, expensive and potentially futile as threats can evolve so much faster than their tree hosts. Also, tree health is not just about a single pest or disease, but about growing trees in the right place, about keeping population sizes up, about ensuring seedlings get a chance to grow and about allowing forests to change as the environment changes. So, in order to find a sustainable long-term strategy for keeping our trees healthy, we need to consider the range of real and potential threats that trees face and try to deal with these together. At the same time, we need to ask what is possible for changing the way we grow trees: how do we use trees now, what do we want from our trees in the future, and how much change are we willing to accept? By finding a middle ground, that brings together the best biological knowledge with a clear understanding of the possible ways to adapt, we can give our trees the best possible chance of withstanding new threats.

The most important part of finding a way to do this is bringing together many different groups of people, and different types of knowledge. A lot is known about many of our trees already, but usually this knowledge comes from unlinked, independent studies and rarely do results from one study tell us something about another, even for the same tree species. Much better coordination is needed. To show how this can be done, we aim to use the example of Scots pine, an important native tree species.

For Scots pine, we know of several serious threats that are either here or are likely to reach the UK soon. The remaining native Scots pine forests are small and fragmented, but we know that they are adapted to their local environments: so pine trees from one part of the country grow differently than those from another. There are large plantations of Scots pine in many parts of the UK - there is ten times as much planted as remains in the native forests - and these are often at much higher densities than are found in nature, and often alongside plantations of pines from other parts of the world. There is also a strong cultural attachment to the species; in many places pinewoods are being replanted and it is often used as a garden or amenity tree.

Our project aims to measure how variable and adaptable are the threats to Scots pine, to test how much variation there is in the tree species in resistance to these threats, and to find ways to get people involved in making healthier pine forests. By doing this we also aim to show how the same thing can be done for any other tree species, and to put in place the tools for getting it done. We will focus on three important threats to Scots pine - Dothistroma needle blight, the pinetree Lappet moth and pine pitch canker. We will bring together a group of scientists - specialists in ecology, tree genetics, forest pathology, plant biochemistry, fungal ecology and evolution and social science - who will work together on the same, carefully chosen pine trees. This work will tell us how much the UK Scots pine population varies and how much it can change from generation to generation; how populations of the threats grow and change; and what can be done to make the pine forests we have more resilient. We will bring in lessons from crop agriculture, where similar problems have been faced for generations, and adapt these for trees and forests, that have much longer lifespans. Finally, by talking to people who work with and use trees, and the general public, we will find ways to use this information to make things change on the ground.

The project will take advantage of existing experimental resources that the consortium has been building for the past few years. These include living experiments (a reciprocal transplant experiment on 3 contrasting sites including 21 native provenances; a glasshouse provenance-progeny trial; field provenance-progeny and provenance trials) and genetic and genomic resources (a large database of mutations across the Scots pine genome and capability for high-throughput genotyping; reference genome for Dothistroma; genetic markers for Dothistroma and pine tree Lappet moth). These existing resources will be made available to the project at no cost.

We will assess distribution and variation in the threat organisms using surveys and genotyping, and study pathogen evolution by characterising genetic changes in samples from different populations. We will assess variation in the host using population genomics (high-density genotyping of samples from multiple populations in trials) and quantitative genetics (analysis of variation in phenotypic traits and extended phenotype - resistance, phenology, morphology, needle chemistry, needle endophyte community). Data from the biological studies will be unified in a spatially-structured database and used, with data on distribution, density and regeneration rates to model the introduction and spread of threat organisms and their interaction with a variable pine population. The models will be used to test scenarios for management change that emerge from stakeholder interactions.

We will use workshops, semi-structured interviews and focus groups with stakeholders (identified through stakeholder analysis) to identify, test and refine options for building resilient pine populations. This will be a dynamic process, with ongoing interaction between natural and social scientists in the consortium, and with stakeholders. Finally, we will create a template for extending the analysis to other tree species.

The project will focus on integrated, interdisciplinary studies involving a species that has clear economic, social and ecological importance in the UK. It will deliver general principles for the development of resilience that are applicable to populations of many other native tree species. In previous and ongoing projects, the research consortium assembled in this project has successfully engaged key stakeholders from the policy, industry, conservation and scientific communities both in their research and its practical implications (see below). This proposal emerged from a meeting held by this consortium in Edinburgh in March 2013, as part of Phase 1 of the Tree Health and Plant Biosecurity Initiative. This was attended by 41 contributors from 24 influential UK organisations. Members of this stakeholder group have been, and will continue to be, involved in shaping the research. They will also help to develop, and participate in, the effective communication of its outcomes and recommendations to the wider stakeholder community, encouraging and facilitating the implementation of these recommendations by practitioners.

During this project we will solicit and integrate the views and expertise of the following key groups: 1. Policymakers: responsible for advice, guidance and regulation of public and private forest and tree management (e.g. Forestry Commission, DEFRA, Scottish Government, JNCC, Scottish Tree Health Advisory Group); 2. Industry: those involved in commercial sourcing, supply and growing of trees including domestic and international seed suppliers and nursery trade (e.g. Elite nurseries, Alba Trees, Scotia Seeds), commercial foresters (individuals, a wide range of private woodland and estate owners and managers and public - e.g. Forest Enterprise, Rothiemurcus / Glen Tanar Estates), others involved in tree planting (e.g. road builders, property developers, councils); 3. Conservation groups: local and nationwide groups with direct interests in tree planting and forest management, or who hold and manage significant areas of forested land (e.g. RSPB, Woodland Trust, Trees for Life, Caledonian Forest Partnership, SNH); 4. The public and other indirect interest groups. Each of these groups have a stake in the management of tree health either directly through their management of tree populations and associated control of pests and pathogens, or through the value that they attach to trees and forests.

Stakeholder participation will be facilitated through a range of activities (workshops, interviews, focus groups) that will form a core part of the project. These will include the development of a science-policy-practitioner interface (SPPI), analysis of values and understanding of key concepts motivating the management of tree health, and design and testing of science-based management options for promoting resilient forests and tree populations. Wider awareness of the key issues will be promoted through knowledge exchange activities, based on previous successful approaches (e.g. RBGE's 'Moving Forward from Ash Dieback'). The scientific community will form a significant part of the stakeholder network and will benefit from the published scientific outputs from the work.

We anticipate that stakeholders will benefit through involvement in the SPPI through knowledge sharing and greater understanding of the risks faced by the trees they manage, the role their trees play in the wider population of this species within the UK, and the options available to them to promote resilience and minimise the impact of pests and pathogens.