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

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 host plant-related activities/businesses and the wider environment. An essential aspect of ensuring Scotland’s preparedness for the possible arrival of Xylella is to prepare a risk map for the likelihood of the arrival of Xylella together with the consequences for key elements of the Scottish economy (directly and indirectly impacted) in the event of an outbreak. Data relevant to the risk mapping for Scotland would include location of sites involved in plant imports, volume of plants imported, impact on business trading in plants if an outbreak is detected and the wider environmental impact.

Impact: This project will contribute to Scottish Government’s contingency and preparedness measures for the possible arrival of Xylella fastidiosa by mapping the risk of likelihood and impact of an outbreak.
Project Lead: Kirsty Park
Xylella fastidiosa is a bacterial plant pathogen that can cause disease in a broad range of hosts, including Polygala myrtifolia, Olea europaea, Rosmarinus Officinalis, Lavandula sp., Prunus sp. and Nerium oleander. 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. The bacteria are transmitted by xylem feeding insects from the Cercopidae family, which include froghoppers and spittlebugs.

There are several species of insects that could vector Xylella fastidiosa in the UK including the meadow spittlebug (Philaenus spumarius), which is very common in Scotland. An outbreak of Xylella in Scotland would have serious impacts on the affected grower/nursery and any other host plant-related activities/business within a 5km buffer zone. Therefore, in order to establish the potential for these bacteria to spread, should they be introduced, it is important to identify and get an understanding of the abundance of potential Xylella vectors in Scotland. The WrEN project (http://www.wrenproject.com/), presents a unique opportunity to make use of existing insect collections to map the occurrence of potential Xylella vectors within agricultural woodlands across Scotland. Since 2013, partners on the WrEN project have surveyed over 130 secondary and ancient woodland sites for habitat and wildlife in two regions of mainland Britain. To date, over 1100 species have been recorded from a wide range of taxa. Vegetation structure has been characterised at all sites including information on tree species richness, tree density and size, understorey and canopy cover. In addition, the surrounding landscape has been mapped at a range of spatial scales up to 3 km from each site.

Impact: This project will contribute to Scottish Government’s preparedness measures for the possible
arrival of Xylella fastidiosa by identifying and mapping the distribution of potential vectors of Xylella
in Scotland.

Publications

Forestry, Environment | Policy Document

Assessment of suitability for EAB invasion for Scotland and the UK

June 2021

Emerald Ash Borer (EAB) has become a significant threat to ash trees in several countries (including USA and Russia) but is not yet present in the UK. We quantified climate and ecological factors affecting EAB suitability using native range data and conclude that southern England is a highly suitable habitat for EAB. Although currently less favourable, we project that Scotland will become increasingly suitable for EAB under climate change. Thus, EAB could threaten Scotland via trade with areas where it is present or, through spread from populations if established in England or Western Europe. Rapid spread of EAB has been observed in its US invasion. We therefore recommend further study and vigilance against EAB introductions into the UK.

Forestry, Horticulture, Environment | Final Report and Policy Document

Metabarcoding analysis of Phytophthora diversity in spore traps and implications for disease forecasting in the P. ramorum management zone

May 2021

Surveillance and monitoring of airborne pathogens is a key tool in the management of healthy forests and controlling disease outbreaks. A Scottish Forestry-funded project was carried out in autumn 2019 to validate different spore-trapping techniques for monitoring airborne P. ramorum inoculum using a species-specific qPCR assay. This project aimed to add further value to the Scottish Forestry project by investigating the suitability of DNA metabarcoding for screening spore trap samples for P. ramorum and other Phytophthora species, seeking early data for aerially dispersed Phytophthora species that may become problematic in UK forests. The study highlighted the value of both monitoring P. ramorum dispersal and detecting other Phytophthora species, to predict and understand changes in disease severity in UK tree host species. Recommendations included that the use of both rain and wind-borne inoculum capture methods might be advantageous due to the variety of weather conditions under which inoculum can disperse.  Lineage testing in Southwest Scotland should be carried out to look at the prevalence of lineage EU1 in the EU2 area and to monitor for presence of North American lineages. Development of a new DNA barcode more specific to Phytophthora would be beneficial.

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

PHC2020/09: Economic Impact of Pesticide Withdrawals to Scotland, with Case Studies

March 2021

Chemical forms of plant protection are widely used in Scottish agricultural, horticultural and forestry production plus for amenity and natural environment management purposes.  The availability and use of active substances in pesticides are closely regulated and increasing concern over human health and environmental impacts has led to a greater likelihood that some existing approvals will be withdrawn and/or that approvals for new products will not be granted.  Potential impacts from withdrawal of these pesticides are of policy interest and this summary report builds on the data and results from project PHC2018/15 (Potential impacts arising from pesticide withdrawals to Scotland’s plant health) and uses case studies to understand the likely magnitude and distribution of potential impacts and how they may be mitigated. 

PHC2018/15: Potential Impacts Arising from Pesticide Withdrawals to Scotland’s Plant Health

November 2020

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.  This project quantifies the impacts on Scottish plant health that will arise from pesticide withdrawal scenarios and sets this in the context and time frame of alternative management tools. 

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.

Expansion of PHC Online Plant Health Resources

May 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.

 

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.