Restoration trajectory of carabid functional traits in a formerly afforested blanket bog

Abstract

The restoration of peatland function and services on damaged peatland sites is seen as an increasingly important goal for ecological, environmental and societal reasons. Restoration monitoring often places fauna as secondary in importance to water table depth and vegetation, and when carried out, it often focuses on taxonomic indices. The use of functional traits, however, can be a complementary approach that clarifies mechanistic links between biodiversity and ecosystem functioning. This study was conducted in large blanket bog site in northern Scotland, using a space-for-time-substitution of restoration sites from which conifer plantations had been removed 2-18 years previously. Carabid beetles were sampled by pitfall trapping in each of three treatments (undamaged bog, restored, afforested). Functional trait data were summarised from available literature. The study found that sites under forestry had different functional traits than blanket bog, and that restoration initially shifted the suites of functional traits away from both forested and open blanket bog. However, no other change in functional traits was observed, and after two decades, restoration sites continue to support carabid communities with higher dispersal capacity and more diurnal activity than the open bog. On the other hand, the functional diversity measures used in this study failed to differentiate the different treatments and further analyses suggest that environment, rather than traits, better explain carabid beetle composition following restoration of formerly afforested blanket bog. In particular, the lack of recovery of typical blanket bog vegetation and microhabitat following felling to waste and drain blocking appear to limit carabid functional recovery.