The vegetation of the Outer Hebrides

Abstract

SynopsisThe paper reviews four topics in relation to the vegetation of the Outer Hebrides: (a)history and flora, (b) environment and habitat, (c) geographical relationship, and (d) conservation. The preliminary flora edited by J. W. Heslop Harrison in 1941 remains the best published list, and there is need for a modern flora. A provisional checklist is presented, based upon recently published data, especially theAtlas of the Bristish Flora(Perring and Walters 1962) and theCritical Supplement(Perring 1968) Miss M. S. Campbell has been responsible for a great deal of recent recording. Geology and climate are critical factors, and soils are mainly peat, except in the extensive machair areas. Significant habitals are coastland, wetland, peatland, moorland and upland. woodland is scarce, though there are good amenity woodlands. Each habitat is reviewed in relation to the floristic lists in theNature Conservation Review(Ratcliffe 1977b). There has been no phytosociological study of the vegetation overall, though particular localities such as St Kilda have been described. The geographical elements are listed, and related to those of Skye, Shetland and Faeroe. The flora is more restricted than that of the mainland. Important categories recognized are (a) species of localized distribution, (b) southern species reaching their northern limits and (c) ‘Atlantic’ species. The origin of the flora is discussed, and it is concluded that the facts have not yet been clearly demonstrated. Eight potential threats are identified as fire, changing agricultural practice including drainage, large-scale peat, sand and gravel extraction, the oil industry, wave-energy generation and tourism.