This aims to be a comprehensive book which describes the plant communities of the British Isles in a straightforward manner. It also integrates information on the role of environmental factors in determining the British vegetation into the main text. The combined action of various environmental factors determines both the structure and distribution of plant communities. It is logical, therefore, to commence the book and individual chapters with information on the climatic, edaphic and biotic factors which influence plant community structure and distribution. Prominence is also given in appropriate chapters, to the importance of ancilliary factors, for example, anthropogenic pressures and the effects of increasing altitude and latitude. These introductory sections are succeeded by descriptions of the principal plant communities of woodland, grassland, heath, freshwater wetland, peatland, salt marsh, sand dune, mountain and urban ecosystems. A few communites of restricted and localized distribution have been omitted. The phytosociological approach to plant community description and classification has been adopted throughout and the associated nomenclature to indicate the various levels in the hierarchial classification are used wherever possible.