EDAPHIC RELATIONSHIPS AMONG CIRSIO-MOLINIETUM AND RELATED WET GRASSLAND COMMUNITIES IN LOWLAND WALES

Soil properties are characterized for a range of the Molinietalia vege tation types in lowland Wales. In this oceanic region there is overlap in the distribution of various forms of wet pasture dominated by Moli nia caerulea and Juncus acutiflorus. There is subtle and continuous va riation in species composition among four communities investigated; th is has been analysed by Detrended Correspondence Analysis and partitio ned between subcommunities recognized in Rodwell (1991). Canonical Var iates Analysis indicated that the main differences in soil conditions between the vegetation classes are related to gradients in base-status ; apparent variation in soil fertility may also be significant and req uires further investigation. In general, Molinia-Cirsium dissectum fen -meadow soils have higher pH, higher Ca-levels, greater base saturatio n and lower acidity than Molinia-Potentilla erecta wet grasslands; tho se of Juncus-Galium palustre rush-pasture and Molinia-Crepis paludosa mire had relatively high levels of inorganic N. The findings are discu ssed with reference to ecological and phytosociological relationships, and also in the context of nature conservation.