S18 - Carex Otrubae Swamp Caricetum Otrubae Mirza 1978

Summary

Synonymy

Caricetum vulpinae R.Tx. 1947 p.p.

Constant species

Carex otrubae.

Physiognomy

The Caricetum otrubae comprises often narrow and fragmentary stands of marginal vegetation in which Carex otrubae is the most abundant species, generally forming an open cover of scattered tufts. No other species is frequent throughout and there is a great variety of associates.

Sub-communities

Carex otrubae sub-community. Here C. otrubae forms a patchy cover interspersed with tussocks of Juncus effusus and/or tall herbs such as Epilobium hirsutum, Iris pseudacorus and Lythrum salicaria. Other swamp dominants like Sparganium erectum and Carex acutiformis may be locally prominent and there are records at low frequency for a wide range of species of water margins and damp mesotrophic grasslands.

Atriplex prostrata sub-community. C. otrubae forms a generally more complete cover in this sub-community with scattered Atriplexprostrata and a low patchy mat of Agrostis stolonifera. The few other species which occur are generally those characteristic of disturbed damp places.

Habitat

This vegetation is characteristic of the clayey margins of standing or slow-moving and moderately eutrophic waters. The Atriplex sub-community extends the distribution of the community to the saline water margins of ditches and pools associated with the salt industry.

Zonation and succession

The Caricetum otrubae characteristically forms a narrow zone between open water and damp mesotrophic grasslands like the Holco-Juncetum. It may form patchy mosaics with other shallow-water swamps such as the Sparganietum erecti and the Carex pseudocyperus community.

Distribution

The C. otrubae sub-community has a scattered distribution throughout the English and Welsh lowlands and the Atriplex sub-community is restricted to the inland saline habitats of Cheshire and Worcestershire. To the north, C. otrubae becomes progressively more restricted to coastal habitats and upper salt-marsh grasslands.

Affinities

The freshwater C. otrubae sub-community is very similar to the C. pseudocyperus swamp and both of these show some affinities with the damp mesotrophic grasslands of the Holco-Juncion. The Atriplex sub-community shows affinities with some communities of the upper salt-marsh such as the Elymetum repentis maritimum and the Oenanthe lachenalii sub-community of the Potentillo-Festucetum arundinaceae. Some authorities (e.g. Westhoff & den Held 1969) consider C. otrubae to be a characteristic species of the Elymo-Rumicion crispi, into which the similar Caricetum vulpinae R.Tx. 1947 has been placed. Although C. vulpina grows in similar habitats to C. otrubae it is a much rarer species in Britain (Jermy et al. 1982) and was not recorded in these samples.