Woodland restoration and consequences for viral communities in Scottish wild rodents

Woodland restoration supports biodiversity recovery and climate mitigation, yet its effects on wildlife parasites and host population health remain poorly understood. Virus communities (viromes) found in wild hosts are influenced by environmental factors and population demographics, however the effect of fine-scale habitat features, landscape composition, and habitat connectivity, which are important factors influencing host ecology, remains to be explored. By investigating patterns and changes in whole virus communities we can identify the underlying ecological mechanisms determining virus circulation and epizootics, with less biased genomic approaches, such as metagenomics, being particularly useful for this purpose. In this study, we describe how restored woodlands features affect the viromes of two common UK species: wood mouse (Apodemus sylvaticus) and bank vole (Clethrionomys glareolus). We sampled wild rodents across 16 restored woodland sites in Scotland that are part of a large-scale restoration natural experiment (www.wren-project.com) to represent different ecological contexts. Using live traps, we collected faecal samples from 263 individuals—45 wood mice and 218 bank voles. We used a metagenomic approach and quantified the effect of vegetation complexity (an indicator of habitat quality and indirect indicator of woodland age) and landscape connectivity on the diversity and relative abundance of vertebrate-infecting viruses found. We also investigated the presence of any viruses with zoonotic potential. Initial results from a pilot study (n = 4 pooled samples) indicate that younger, less structurally complex woodlands have lower viral diversity. Host species also appears to influence viral abundance and diversity, with bank voles showing significantly higher viral diversity than wood mice. These preliminary results highlight the potential effect of host species and time since restoration of woodland sites in determining viral communities. Ongoing analyses are expanding these results that will help us identify the key predictors of the diversity and abundance of viruses in restored woodland ecosystems. These findings have practical implications for woodland management and will advance our understanding of the links between habitat recovery, host–virus ecology, and wild population health.