Vegetation responses to experimental prescribed burning and cutting of heather on blanket peat sites managed as grouse moors in northern England

Abstract

Aims: To contribute to an evidence-based position on the effects of prescribed burning and mechanical cutting of heather-dominated swards on blanket bog vegetation recovery. We tested our primary hypothesis that management reduces heather Calluna vulgaris dominance and subsequently increases the cover of vegetation enhancing peat formation such as Sphagnum mosses and Eriophorum vaginatum. Location: The Pennine Hills in northern England. Methods: We established a randomised plot-based Before-After-Control-Impact (BACI) experiment, replicated over four blocks at each of five blanket bog peatland sites managed for red grouse Lagopus scotica shooting. The experiment compared the effects of prescribed vegetation burning and two cutting methods (brash left and brash removed) on the composition and structure of moorland vegetation with those on no-management (control) plots. We describe post-management changes in the first five years following management implementation relative to pre-management (baseline) measures in the same plots and to spatial no-management controls. Results: Management interventions reduced both heather cover and vegetation height relative to pre-management measures and no-management controls. Heather reduction was associated with increases in E. vaginatum, Sphagnum, and other ericaceous species. Management initially reduced moss depth and was linked with increases in acrocarpous moss cover following burning and pleurocarpous moss cover following cutting. Leaving cut brash slowed the rate of Sphagnum cover recovery and may increase the risk of wildfire. Conclusions: Management reduced heather cover and promoted peat-forming species associated with carbon sequestration. Cutting produced comparable results to burning and formed an additional tool for managing vegetation on blanket peat. All managements reduced fuel loads but leaving cut brash added to the litter layer and may increase the risk of wildfire ignition. Further and longer-term research on cutting needs to help define best practice that reduces impacts on the moss layer and peat surface and their relation to wildfires. Our results have broad implications for heathland and peatland habitat restoration beyond those in the UK.