| Summary: | A review of phytosociological techniques, including the Zurich-Montipellier (Z-M) system. Association analysis and simple ordination is made, using a standard data set. The complementary nature of the results obtained is noted. As classification erects divisions and boundaries in a data set, and the prime method used in the analysis of heath vegetation is classificatory, evidence for the prescence of 'real' vegetation boundaries is presented, together with a discussion of their nature and function. Heathland vegetation in Britain has been classified using the Z-M phytosociological system, and four main types have been distinguished, which are equated with alliances at present in use in Europe. These are; Erica cinerea Heath: Ulicion nanae (Duvigud, 1944)em. Van den Bergen. Calluna vulgaris Heath: Calluno-Genisition pilosae (Duvignd, 1944) Vaccinium myrtillus Heath: Llyrtillion bore ale (Bocher, 1943). Erica tetralix Heath: Ericion tetralicis (Schuick, 1933).The first three are typical of Dry heaths, whereas the fourth indicates wet heath. A phytogeographical analysis of the Heath vegetation gives further validity to these four types, indicating the dependence of the three dry 'Heaths' on species which are geographically restricted. Use of the Z-M system and some other techniques to indicate the nature of recent vegetation in areas now urbanised or agriculturalised is made, using South Gloucestershire as such an area.
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