The response of plants, carabid beetles and birds to 30 years of native reforestation in the Scottish Highlands

Globally, there is increasing interest in tree planting, leading to many country-level commitments reforestation. In the UK, current would achieve 17% forest cover by 2050, with highest rates of expansion expected Scotland. Forest native trees increase biodiversity, particularly woodland specialist species, and associated ecosystem services. Despite this, data on biodiversity changes over early stages reforestation are sparse, for upland areas Scotland where opportunities greatest. We collected response plants, carabid beetles birds grazing exclusion, using sites reforested last 30 years Scottish Highlands. Biodiversity ungrazed, was compared unforested controls mature forest, both grazed ungrazed. Mean bird species richness plots (4.4 [95% CI: 3.2, 5.9]) higher than (0.8 [0.5, 1.3]), but lower (7.0 [5.4, 8.3]). contrast, no systematic difference plant or beetle reforested, plots, between ungrazed any groups. Woodland were found predicted reach levels c. 36 after Species assemblages differed across habitat categories. For intermediate sites. beetles, comparable from Grazing did not strongly influence assemblages. Policy implications. show that specialists colonise transition towards those target within first species. Native should be prioritised Scotland's future targets, given scarce fragmented Highlands ultimate gain may accrue long time-scales.