S9 - Carex Rostrata Swamp Caricetum Rostratae Rübel 1912

Summary

Synonmy

Carex ampullacea consocies Matthews 1914; Caricetum inflatae Tansley 1939; Carex rostrata ‘reedswamps’ Holdgate 1955/? p.p.; Carex rostrata sociations Spence 1964 p.p.; Carex rostrata reedswamps Proctor 1974; Carex rostrata nodum Daniels 1978; Caricetum rostratae Birse 1980 p.p.

Constant species

Carex rostrata.

Rare species

Eriocaulon septangulare.

Physiognomy

The Caricetum rostratae is generally dominated by Carex rostrata which characteristically forms a somewhat open cover of tufted shoots usually 50-60 cm tall. No other species is frequent throughout and the vegetation is typically species-poor.

Sub-communities

Carex rostrata sub-community. Open Carex rostrata sociation Spence 1964. This sub-community includes pure and very species-poor stands overwhelmingly dominated by C. rostrata. Equisetum fluviatile, Polygonum amphibium and Potamogeton natans occur occasionally.

Menyanthes trifoliata-Equisetum fluviatile sub-community: Carex rostrata-Menyanthes sociation Spence 1964; Carex rostrata-Menyanthes trifoliata Association Birks 1973. Here, the vegetation comprises mixtures of C. rostrata, Equisetum fluviatile, Menyanthes trifoliata and Potentilla palustris sometimes developed as a floating mat. Although the sedge is generally dominant, each of these associates may be locally abundant, the bulky foliage of M. trifoliata and P. palustris often appearing particularly prominent among the thinner sedge and horsetell shoots. Eleocharis palustris, Carex nigra, Ranunculusflammula, Calthapalustris and Potamogeton polygonifolius are occasional. Lobelia dortmanna and Littorella uniflora are uncommon, though sometimes abundant and, on Skye, Eriocaulon septangulare occurs in this vegetation.

Habitat

The Caricetum rostratae is typically a swamp of shallow to moderately deep, mesotrophic to oligotrophic, standing waters with organic substrates. Although found down almost to sea-level, it is one of the few swamp communities that makes a major contribution to the vegetation of upland lakes where stands may be extensive. It also occurs more fragmentarily in peat cuttings.

Although the community can be encountered on silty or sandy substrates, it is more typical of an organic base, often being rooted directly in firm peat (as where the Carex sub-community is colonising existing underwater deposits) or spongey peat ooze (especially under the Menyanthes-Equisetum sub-community which produces abundant litter). pH values of 5.0-6.8 have been recorded but the waters may be nutrient-poor and the Caricetum rostratae includes stands which extend the occurrence of swamp vegetation into highly oligotrophic situations.