Grazing Management and Plant Community Composition on Bodmin Moor

Abstract

The research presented in this thesis was focused on aspects of the dynamic response of upland vegetation to grazing, to allow evaluation of the suitability of Countryside Stewardship (CS) management for the rehabilitation of dwarf-shrub cover in the upland landscape of Bodmin Moor. Initial chapters review the ecological character of Bodmin Moor, grazing management and vegetation in upland habitats, and succession in relation to grazing. Chapter Five provides the first extensive and detailed phytosociological investigation of the vegetation of Bodmin Moor-providing a baseline for further work. It also examines the spatial distribution of the plant communities in relation to environmental gradients and grazing management. Bodmin Moor was dominated by acid grassland and mire with some small heathland fragments. It lacked the cover of ericaceous dwarf-shrubs that define heathland in the rest of Britain. Chapter Six provides the first description of the soil seed banks on Bodmin Moor and determined that seed availability was not limiting the rehabilitation of dwarf-shrub cover. Chapter Seven utilised an existing monitoring scheme on Bodmin Moor North SSSI to identify vegetation changes associated with the establishment of a CS management regime. It was found that CS grazing levels were not high enough to suppress Molinia caerulea and dwarf-shrubs were not favoured. Chapter Eight reports on a Molinia caerulea defoliation experiment, which suggested that heavy summer grazing was the most suitable grazing option for the control of Molinia caerulea using livestock. Unfortunately, other work indicates that this is not compatible with the maintenance of dwarf-shrubs. CS protocols may not be suitable for dwarf-shrub rehabilitation on the graminoid-dominated vegetation of Bodmin Moor. Furthermore, the desirability of the objectives of CS can be questioned, and they may be impossible to achieve by the manipulation of grazing regimes alone (Chapter Nine).