Description

This horizon-scanning project uses phylogenetic approaches to address two research questions:

1. Which non-native tree species proposed for future planting in the UK are likely to be the most susceptible to native pests and pathogens?
2. Which non-native pests and pathogens pose the greatest future threat to Sitka spruce, a key non-native tree species already widely planted in the UK?

1. Susceptibility of non-native trees to native pests and pathogens

We are assessing the likely susceptibility of non-native tree species to native pests and pathogens in the UK by undertaking the following tasks:

• Compiling a list of candidate non-native tree species for future planting in the UK, based on databases and expert knowledge.
• Analysing phylogenetic distance between non-native tree species and UK native plants from published large-scale molecular analyses.
• Reviewing the literature to collect data on organisms associated with the closest relatives of non-native trees, which are potentially harmful to tree health.
• Ranking the candidate non-native tree species according to likely risk, based on their phylogenetic distance from native tree hosts of potentially harmful organisms.

2. Susceptibility of Sitka spruce to non-native pests and pathogens

• Compiling a list of potential pests and pathogens of Sitka spruce based on databases and expert knowledge.
• Analysing phylogenetic distances between Sitka spruce and known hosts using a published time-calibrated phylogenetic tree for gymnosperms.
• Generating a phylogenetically informed ranking of pest/pathogen species on the basis of the minimum phylogenetic distance between a known host of that species and Sitka spruce, with those with the most closely related host species considered to pose the greatest risk.

Outputs

• Ranked lists of non-native tree species based on likely risk posed by native pests and pathogens. MS1: Candidate non-native tree list compiled; MS2: Analysis of phylogenetic distance from native plants completed; MS3: Potentially harmful organisms associated with native plants identified; MS4: Ranked lists of non-native trees generated; MS5: Report drafted for Defra.
• Ranked list of pests and pathogens based on the likely susceptibility of Sitka spruce. MS1: List of potential threat species and their known host ranges compiled; MS2: Analysis of phylogenetic distance completed; MS3: Ranked list of pests and pathogens generated; MS4: Report drafted for Defra.