Forestry

The sector represents a major component of Scotland’s rural economy – providing significant employment and raw materials for wood processing industries.  Sustainable forest management seeks to deliver these economic benefits alongside important ecosystem services such as carbon sequestration and flood mitigation, provision of wildlife habitat and opportunities for recreation and a range of leisure activities.  Pests and diseases threaten the continued long-term delivery of these benefits.

The forest area of Scotland expanded during the twentieth century through the efforts of the Forestry Commission and private owners to develop a domestic wood supply and provide rural employment.  A number of introduced species, such as Sitka spruce, were key to afforestation of marginal agricultural sites and now are central to the wood processing industry.  Woodland now occupies approximately 17% of the land area of Scotland and provides 44% of the GB softwood harvest, producing about 1.5 million m3 of sawn softwood.  Plant health threats to the forestry sector include a number of recently introduced pests and diseases (e.g. Phytophthora ramorum, pine tree lappet moth, ash die-back), on-going management of endemic ones (e.g. large pine weevil and Heterobasidium annosum) and risks of those yet to arrive (emerald ash borer, Ips typographus and many other organisms potentially introduced through trade in plants, wood and packaging).

Projects

Project Lead: Mariella Marzano
The UK and Scotland have ambitious tree planting targets, with a major driver being carbon sequestration. Scotland’s Forest Strategy outlines a target of 15,000 ha per year. In addition to carbon management, other major drivers for tree planting are commercial forestry, habitat restoration and the establishment of new woodlands for biodiversity and amenity value. Scotland’s Forest Strategy outlines a target of 3,000-5,000 ha of new native woodland per year, and restoration of an additional 10,000 ha of native woodland. This involves planting a large volume of trees. There is considerable uncertainty as to where and how this volume of trees will be sourced, and associated uncertainty as to the biosecurity threats posed. The aim of this project is to improve our understanding of current biosecurity awareness and practices within the arenas of woodland creation/ expansion and habitat restoration in Scotland.

Impact: Determine the main barriers to ensuring that future planting for environmental restoration and conservation will minimise plant health risks.
Project Lead: Mariella Marzano
Large scale infra-structure projects such as transport networks and major housing projects typically include extensive landscaping and planting programmes. These operate at a large scale, often require instant visual impacts (semi-mature shrubs and trees) and face significant cost pressures. The modest scale of domestic production creates challenges in obtaining material from local sources, which can favour low-cost large-scale plant imports with associated risks of pest and disease entry. This project will fill in key knowledge gaps with those responsible for selecting, procuring and planting plants and trees on a large-scale to provide an understanding of how/whether biosecurity features in their decision-making and make recommendations for any changes required to improve bio-secure practices.

Impact: Provide Scottish Government policy with an assessment of the major biosecurity pitfalls and opportunities arising from large-scale landscaping plantings.
Project Lead: Mariella Marzano
Retail horticulture is a large-scale industry in the UK, with ornamental horticulture and landscaping worth an estimated £24.2 billion national GDP in 2017. The industry is characterised by a large volume of individual transactions and the transport of a diverse range of plant materials (with accompanying soil and packaging) to a highly distributed set of final destinations (households). These horticultural sales represent a complex and pervasive vector network, which carries the risk of transportation of pests and pathogens to surrounding parks and gardens, agricultural systems, woodlands, forests and the wider environment. The diversity of the plant material in trade and the multitude of suppliers and recipients creates a major challenge for managing biosecurity. This project will identify decision-makers, their knowledge, attitudes, and behaviours relating to plant health, and assess opportunities and barriers to better plant biosecurity and the potential role of a Plant Health Assurance Scheme.

Impact: This project will enable policy to identify and prioritise plant biosecurity vulnerabilities from non-specialist and online horticultural sales.
Project Lead: Carolyn Riddell
The oomycete Phytophthora ramorum has caused substantial losses of Scottish forests in recent years due to widespread mortality of European larch trees (Larix decidua). Since 2009, legislation and policies have been implemented to control P. ramorum outbreaks on larch including the use of a 250 m larch ‘fire-break’, although it is unclear whether this distance is optimal for disease control. A project funded by Scottish Forestry is using a P. ramorum-specific qPCR assay to compare several spore trapping techniques for quantifying wind- and rain-borne inoculum and to better estimate inoculum dispersal distance. This project adds value to that of the Scottish Forestry-commissioned work, through evaluation of metabarcoding as an alternative method to both monitor P. ramorum inoculum dispersal and detect a broader range of aerially dispersed Phytophthora species. A second objective is to determine the lineage composition of P. ramorum inoculum throughout the observed peak sporulation period.

Impact: Timely management and prioritisation of policy to manage P. ramorum and facilitate early forecasting of other Phytophthora outbreaks.
Project Lead: Katy Hayden
A previous PHC project (PHC2018/11) created an online Resource Bank for plant health threats to the Natural Environment sector in Scotland, which includes an assembly of, or signposting to, available existing resources. The PHC recognised that for the remaining three sectors (Forestry, Agriculture and Horticulture) information on plant health is more available but the quality and relevance to Scotland is often not clear. The aim of this project is to expand PHC’s online resource to signpost users and practitioners to relevant and reliable information and to address a broad spectrum of plant health topics, from diagnostics and control to outreach and education for agriculture, forestry and horticulture sectors.

Impact: Expand the PHC online resource to create a comprehensive and unique signposting resource for plant health information for all sectors.
Project Lead: Glenn Marion
Dendroctonus Micans (D. micans) is a significant beetle pest of commercially important spruce species. The beetle is spreading north from England and is now present is Scotland. The spread of the beetle threatens the D. micans Pest Free Area (PFA) in west Scotland. This designation allows the transfer of the Scottish Spruce crop from the PFA to Irish sawmills, as Ireland is a D. micans free area. The Central Belt of Scotland is a relatively spruce free area and may act as a natural ‘firebreak’ to slow or stop the spread of the beetle. Scottish Forestry collect field data in annual surveys and release an obligate predator (i.e. a predator that can only survive in the presence of D. micans) at sites with observed D. micans infestation and sites believed to be at high colonisation risk. This project conducted a proof of principle study to assess whether developed computational tools could add value to the field data in annual surveys by Scottish Forestry to parameterise models of the spread of D. micans in space and time. The fitted model was also used to project scenarios of future spread.

Impact: Informed the control efforts of Scottish Forestry by predicting the spread of D. micans in Scotland and identifying the high-risk areas of colonisation. This project built on methods developed under the RESAS SRP and led to work commissioned by Scottish Forestry to inform their surveillance and control programme in 2018.
Project Lead: April Armstrong
The oomycete Phytophthora ramorum has caused substantial losses of Scottish forests in recent years due to widespread mortality of European larch trees (Larix decidua). Infected trees are subject to statutory felling notices in an effort to reduce sporulation potential. Nevertheless, there are concerns about the multiple pathways by which spores might be transferred to new sites. There have been assessments of soil moved by mountain biking and walking/running resulting in evidence to support the Forestry Commission’s Keep-it-Clean campaign. This study will assess soil/plant material collected from commercial harvesting equipment (tyres, treads, mud guards etc.). PHC support will enable a wider range of diagnostic tests to be carried out, testing the robustness of the methods and examining the potential for multiple Phytophthora species to be transferred.

Impact: Add to the evidence base underpinning public and sector-facing biosecurity campaigns and improve disease management and restrict spread of the disease.
Project Lead: Daniel Chapman
Xylella fastidiosa is a bacterial plant pathogen that can cause disease in a broad range of hosts. Disease symptoms include leaf scorch, wilting of foliage, dieback and plant death. Xylella fastidiosa was first detected in Europe in 2013 in Puglia in Italy and was identified as subspecies pauca which has gone on to devastate olive plantations in this region. There are currently major Xylella outbreaks in Southern France, including Corsica, Italy, mainland Spain and the Balearic Islands. Although Xylella has so far not been detected in Scotland, an outbreak would have serious impacts on any businesses where Xylella is detected and the wider environment. An essential aspect of ensuring that Xylella is not introduced to Scotland is to establish, through modelling, that national surveillance monitoring aimed at detecting a Xylella outbreak is effective. In addition, it is important to identify which epidemiological parameters most strongly influence the effectiveness of surveillance, to guide where future empirical research should be targeted to reduce any uncertainty.

Impact: This project will contribute to Scottish Government’s preparedness measures for the possible arrival of Xylella fastidiosa by ensuring surveillance monitoring is effective and by identifying the key knowledge gaps for effective surveillance.
Project Lead: Andy Evans
The use of pesticides to manage plant pests and diseases is a key management intervention across plant health sectors, particularly in agriculture, horticulture and commercial forestry production. Pesticide withdrawals through legislation, coupled with resistance development, and their impact on plant health have emerged as key concerns for Scottish plant health stakeholders. There is an urgent need to quantify the impact on Scottish plant health that will arise from pesticide withdrawal scenarios and to set this in the context and time frame of alternative management tools. This will be used to inform recommendations on pesticide strategy at the Scottish, UK and EU levels going forward. A synthesis report of available information is required to identify products at risk and work through scenarios for the plant types, pests and diseases of importance in Scotland. This will be a project where cross-sectoral dialogue between the plant health sectors of agriculture / crop production, horticulture, forestry and the environment will be necessary. The project will review existing information and a key output will be summary recommendations appropriate for use by policy makes. The bid must include time to engage with in cross-sectoral dialogue and with Scottish Government staff to discuss and progress early drafts.

Impact: Improved understanding of costs and benefits of pesticide use across Scottish sectors and an impact analysis for the most likely withdrawal scenarios such that key gaps can be identified and their impact quantified in order to inform pesticide policy.
Project Lead: Adam Kleczkowski
The movement of plant pests and pathogens into Scotland in likely to increase in the coming years, e.g. due to changes in trade, potentially increasing from outside Europe following Brexit, while their spread and severity could be affected by climate change (both positively and negatively). It is therefore vital that we understand the role of climate on the impacts of such pests and diseases across the whole of Scotland, in relation to the distribution of plant hosts, allowing us to target potential control options on the main threats. To allow plant health professionals and others to assess such impacts in as straight forward a way as possible, web- / desktop-based tools are needed that offer quick and easy access to complex computer models. These models should be as comprehensive as possible, allowing new information on pests, pathogens and their hosts to be added as it becomes available.

Impact: Easily accessible tool for PHC and government plant health officials to assess possible impacts of climate on pests and pathogens in Scotland.

Publications

Expansion of PHC Online Plant Health Resources

July 2020

This project has expanded the PHC online Resource Bank for plant health threats to the Natural Environment sector in Scotland to include information sources for the remaining three sectors (Forestry, Agriculture and Horticulture). Information sources for Forestry, Agriculture and Horticulture were compiled and evaluated, and a Knowledge Bank relevant to each sector is now online at the PHC website, creating a comprehensive and unique signposting resource for plant health information with relevance to Scotland.

 

Impact of climate change on the spread of pests and diseases in Scotland

June 2020

This project constructed a modelling framework which combined epidemiological and economic modelling.  The modelling framework was used to study predictions of spread and economic impact of pests which are not currently in the UK, including Xylella fastidiosa, Candidatus Liberibacter solanacearum (Zebra chip) and Ips typographus (Eight toothed Spruce Bark Beetle). 

Impact:  A web/desktop application is available to the PHC and Scottish Government to analyse the effects of climate change on the spread and economic impact of new threats. 

Forestry | Final Report

Modelling Framework for invasive pests: Emerald ash borer as a case study

June 2020

This project investigated whether modelling could aid preparation for a potential bark beetle and wood borer invasion of Scotland. This was achieved by: (i) reviewing suitability of modelling results and frameworks in literature; (ii) recommendations on how these could be rapidly adapted for Scottish and UK plant health context and (iii) case study on Emerald ash borer to exemplify approach.

Forestry, Environment | PHC Pest Review

Threat: Bud worm

Authors: Chris Quine
October 2019

Status, Scottish specific issues, Plant Health Centre perspective and Key priorities and recommendations concerning the threat from the Eastern spruce budworm (Choristoneura fumiferana), Western spruce budworm (C. freeman) and  Black headed budworm (Acleris gloverana and A. variana) to Scotland

Forestry, Environment | Final Report and Policy Document

Development of an online, user friendly plant health resource bank for the Scottish Natural Environment

August 2019

The aim of the project PHC2018/11 was to compile a resource to be embedded within the Scottish Plant Health Centre (PHC) website, with the following three main purposes: 1) To direct users to existing, comprehensive and reliable plant health information resources; 2) To provide information on selected plant health threats to the natural environment, particularly invasive non-native species; and 3) To direct users to appropriate government agencies and resources and advise users on steps to take should a suspected statutory pest or disease be encountered.

Webpages have been developed which provide the following:

1) a listing of the first most pressing plant health threats to the natural environment in Scotland;

2) a user-friendly web template, populated with links to information about these major threats and other topics relevant to plant health in the Scottish natural environment; and

3) summary pages providing guidance on biosecurity and control of diseases in this sector, for which other resources were not easily available.

Forestry, Horticulture, Agriculture, Environment | Final Report and Policy Document

The use of mobile technology to enhance plant health monitoring and awareness in Scotland

August 2019

The aim of the project was to review existing websites and smartphone apps currently available and applied in the plant health sector and to assemble a detailed overview covering the following points:

  • What options are available in terms of mobile software applications for plant health?
  • What is their primary purpose?
  • Who is the target audience (growers, plant health professionals, citizen science, …)?
  • Which plant health sectors do they cover?
  • Are they reliable and accurate?
  • Is information submitted to a central database? If so, how is this information used?
  • Could they be used globally, or are they limited to certain geographic regions?

Difficult choices to protect gardens and the environment

Authors: Katy Hayden
September 2018

Heritage gardens play an important role in plant conservation. They house collections gathered over decades or even hundreds of years, including varieties of plants that may be overlooked elsewhere, fostering heirloom varieties and preserving biological diversity that is the raw material of adaptation. As well as being beautiful and tranquil sites of cultural heritage, these ex-situ resources are treasure troves of biological diversity. Arduaine Gardens shows us that tough choices can be necessary and important to preserve these collections and the surrounding environment.