Carex Riparia Swamp Caricetum Ripariae Soo 1928 157 Carex Acuta in Swamps and Fens

Synonymy Caricetum acutiformo-ripariae Soo (1927) 1930 p.p.; Caricetum acutiformo-paniculatae VI. & Van Zinderen Bakker 1942 p.p.; Angelico-Phragmitetum caricetosum ripariae Ratcliffe & Hattey 1982. Constant species Carex rip aria. Physiognomy The Caricetum ripariae is generally dominated by Carex riparia, the large tufts of which carry erect leaves forming a sometimes dense canopy usually more than 1 m tall. The vegetation is typically rather species-poor and pure stands are not uncommon. Frequently, however, the community is marked by the patchy abundance of other swamp emergents and/or tall herbs. Among these, Phragmites australis, Equisetum fluviatile, E. palustre, Epilobium hirsutum, Phalaris arundinacea and Filipendula ulmaria are the most frequent and there is occasionally prominent Galium palustre and Mentha aquatica. Less frequent, though sometimes conspicuous, are Sparganium erectum, Typha latifolia, Juncus effusus, Lycopus europaeus, Oenanthe crocata, Solanum dulcamara and Carex acuta. Habitat The community seems to be most characteristic of wet or waterlogged, mesotrophic to eutrophic, circumneutral mineral soils alongside standing or slow-moving waters. It occurs, sometimes as large stands, by sluggish rivers and streams, in drainage ditches, around ponds and lakes and in clearings within fen woodlands, always in the lowlands. The Caricetum ripariae has been observed growing as emergent vegetation in up to 20 cm of water but, even where the water-table falls below the surface, the substrate very typically has an upper layer of very sloppy sapropelic silt. pH values of 5.8-7.0 have been recorded. Zonation and succession The community often forms part of riparian sequences which frequently terminate abruptly above in agricultural boundaries. Stands within wet woodlands may pass gradually to the surrounding vegetation with the C. riparia remaining a prominent component of the field layer. Distribution The Caricetum ripariae is typically a community of the agricultural lowlands of England and Wales but, although C. riparia retains an extensive distribution over much of this ground (Jermy et al. 1982), extensive stands seem to be declining in the Midlands and East Anglia (C. D. Pigott, personal communication). In Wales, the community remains quite widespread in the southern coastal lowlands and is especially distinctive of the valley and flood-plain mires of Pembrokeshire (Ratcliffe & Hattey 1982).