Impacts of mammals on trees and tree protection methods pertinent to English treescapes - a systematic literature review for Forestry Commission

We conducted a systematic literature review as part of a Forestry Commission (FC) contract to provide good practice technical guidance to manage impacts of mammals on trees, woods, establishing woodlands and treescapes. The review examined both the positive and negative impacts of mammals and existing tree protection options and best practice. Using the PRISMA (‘Preferred Reporting Items for Systematic reviews and Meta-Analyses’) framework (Page et al., 2021), we systematically searched for relevant scientific, peer-reviewed literature. We also conducted targeted organisational searches for grey literature relevant to the objectives within an English context. We then implemented a thematic tagging process to facilitate the synthesis of findings across both types of literature, whilst building a categorised resource bank. Following exclusions, we identified and tagged 281 scientific literature sources and 218 grey literature sources. We identified eight key species or functional groups of mammals (beavers; small mammals; grey squirrels; lagomorphs; pigs and wild boar; deer; livestock including feral sheep and goats and bison; and horses and ponies) that have distinct tree protection approaches available, relating to their ecology, behaviour, type of damage caused and legal restrictions. We also developed a novel ecological framework to categorise tree protection methods according to their strategy of intervention within mammal-tree interactions and applied it to each species/functional group. Finally, we provide an extensive synthesis of the literature for each species or group, detailing literature relating to ecosystem services, damage to trees, identification of that damage, and resultant protection methods identified. This document thus provides a foundation for developing the practitioner-focussed technical guidance.