Synonymy

Caricetum acutiformo-ripariae Soo (1927) 1930 p.p.; Caricetum acutiformo-paniculatae VI. & Van Zinderen Bakker 1942 p.p.; Carex acutiformis fen Lambert 1951 p.p.; Carex acutiformis stands Meres Survey 1980 p.p.

Constant species

Carex acutiformis.

Physiognomy

The Caricetum acutiformis is always dominated by Carex acutiformis forming an open or closed canopy of shoots and arcuate leaves about 1 m tall. No other species is constant but there are usually some scattered tall fen herbs such as Angelica sylvestris and Valeriana officinalis and shorter species like Galium palustre and Mentha aquatica. Other swamp species, e.g. Carexpaniculata, Sparganium erectum and Typha latifolia, may be locally prominent, and Juncus effusus is sometimes abundant. However, many of the occasional reflect the particular floristic context of the often small stands.

Habitat

The community seems to be typical of situations which are, in some respects, similar to those occupied by the Caricetum ripariae. It has been recorded from moderately eutrophic, circumneutral substrates on the margins of slow-moving or standing lowland waters in openwater transitions, in wet hollows within flood-meadows, in ditches and alongside sluggish streams and rivers. Here the water-level may be up to about 20 cm above ground and the substrate pH 6.0-6.8. There is some evidence, however, (e.g. Haslam 1978), that the Caricetum acutiformis is more consistently associated with calcareous habitats than is the Caricetum ripariae'. it occurs, for example, in ditches in fen peat and also on the margins of slow chalk streams.

Zonation and succession

Around more extensive open-water transitions, the community may form swamp which passes gradually to fen in which C. acutiformis remains a prominent component, e.g. some forms of the Peucedano-Phragmitetum, and it was from such situations that Lambert (1951) described her C. acutiformis sere along the Bure valley in Norfolk. At more abrupt water margins, the community occurs in often narrow and fragmentary transitions with the Sparganietum erecti towards deeper and, to landward, the Glycerietum maximae or Phragmitetum australis. Unlike the Caricetum ripariae, this community may also form swampy patches in calcareous floodmeadows and flood-pastures, passing gradually through some form of Calthion community to damp mesotrophic grassland, but, with agricultural improvement, such transitions are becoming more rare. C. acutiformis seems to be quite an aggressive species which may be able to readily invade riverside fields where drains become blocked. It also appears to be able to tolerate cattle grazing (Wheeler 1975).