Plant Communities of Rich-Fen Systems in England and Wales: II. Communities of Calcareous Mires

Abstract

(1) A floristic classification is presented of the species-rich plant communities of calcareous mires (Caricion davallianae) in England and Wales. (2) Three main syntaxa (Associations) are recognized. The Schoeno-Juncetum subnodulosi is a widespread, though infrequent, community of lowland spring fens and valley fens (mainly below 100 m O.D.), mainly in the south of Britain. The Pinguiculo-Caricetum dioicae is a widespread community of spring fens which is found mainly in northern England in calcareous upland and lowland situations. The Acrocladio-Caricetum diandrae occurs in topogenous calcareous fens; it has a wide distribution in England and Wales, but most examples occur in the north, and although predominantly a community of the lowlands it is also known from some more upland sites (up to 370 m O.D.). (3) Brief discussion is made of some of the factors that may be important in determining the composition of calcareous mire communities. It is suggested that most of these communities are probably developed in comparatively infertile and unproductive habitats where nutrients such as phosphorus are only sparingly available.