DOI: 10.5285/00601c2a-ac86-467d-8696-689cf20e35d3
title: Spatial risk analysis for Phytophthora ramorum infection in heathland fragments in Scotland

description: This dataset maps the risks of Phytophthora ramorum infection for 47587 fragments of Heather heathland (UKCEH Landcover Map class H9) and 74869 fragments of Heather grassland (UKCEH Landcover Map class H10). Fragment risk scores integrate climate suitability for P. ramorum (using pathogen-specific temperature-dependent growth curves and a relative humidity threshold), proximity to Larch/infected Larch within 500m or 5000m, proximity to other (non-Larch) wider environment infections within 1500m, habitat suitability within the fragment for sporulating hosts (Vaccinium myrtillus, V. vitis-idaea, Acrostaphylos uva-versi) and the reservoir host Rhododendron ponticum, proximity to inspected premises with confirmed infections and the presence of water courses. The maximum possible risk score for heathland fragments across all risk factors was 11.5, but in practice the maximum assigned for any fragment was 10.5 for Heather (H9) and 11 for Heather grassland (H10). Fragments were also classified as low, medium or high risk (overall_risk_as_range).
description: We employed an iterative and collaborative co-production process that brought together stakeholders with diverse expertise from across Scotland’s plant health sector, including forestry, conservation, horticulture, and government agencies to co-design the risk framework. Heathland fragments in Scotland were identified using the Land Cover Map 2023 (land parcels, GB). Risks were scored separately for the two classes of heathland defined in the LCM. Heathland 9 relates to LCM Class ‘Heather’ (>25% cover Heather) and heathland 10 is Heather grassland (≤25% cover heather). Key risk factors for P. ramorum infection and their scoring were agreed with 15 cross-sectoral stakeholders through a self-completion survey and two workshops. The previous risk analysis for P. ramorum risks to heathland fragments has been updated to include new P. ramorum detection data in Larch woodlands and inspected premises provided by Scottish Forestry and SASA. New climate suitability models for P. ramorum growth are used. The risk scoring has been adjusted to reduce the emphasis on proximity to inspected premises as a pathway of spread, reflecting stakeholder perspectives on improved biosecurity practices in trade. The scored fragment data were intersected with the boundaries of local authorities, terrestrial protected areas, and P. ramorum policy zones to summarise the distribution of risks across regions in Scotland.

The final report was peer reviewed by the Plant Health Centre. In addition, a knowledge integration and validation workshop (November 13, 2024) examined the adequacy of the outputs for horizon scanning and decision-making across sectors. Validation of the climate suitability models for P. ramorum has been attempted using independent UK and European detections. This spatial risk framework cannot yet be fully validated until future detections are available, because previous detections are used within the model and are not independent of the risk scores assigned. Previous risk frameworks were cross-validated against subsequent, independent P. ramorum detections, as proof of concept.