SM16: Festuca rubra salt-marsh community: Juncetum gerardi Warming 1906

Summary

Synonymy

Festucetum (rubrae) auct. angl.

Constant species

Festuca rubra, Plantago maritima, Glaux maritima.

Physiognomy

The closed grasslands of the Juncetum gerardi are normally dominated by mixtures of Festuca rubra and Agrostis stolonifera with a variety of herbaceous associates among which Plantago maritima, Glaux maritima, Armeria maritima and Triglochin maritima are generally the most frequent and abundant. Juncus gerardii itself is present in varying amounts: it is usually constant through all but the most anomalous of the Juncetum swards and in some cases is dominant or co-dominant. In certain subcommunities, there are frequent records for low-marsh species and an algal mat is often conspicuous over the substrate surface. In other sub-communities, a group of mesotrophic grassland and flush species are well-represented. The Juncetum gerardi is the community within which bryophytes reach their lowest limit on salt-marshes.

Sub-communities

As in the other major British salt-marsh association, the Puccinellietum maritimae, variation is virtually continuous, largely based on quantitative differences among relatively few species and frequently including a site-specific element reflecting local histories of marsh use. The following sub-communities should therefore be seen as foci of national variation with somewhat hazy boundaries.

Puccinellia maritima sub-community: Juncus gerardii-Puccinellia maritima nodum Adam 1976; Puccinellietum maritimae agrostidetosum Beeftink 1962. This sub-community comprises generally short swards which are floristically transitional between the Juncetum gerardi and the Puccinellietum maritimae. J. gerardi, Puccinellia maritima, Festuca rubra, Plantago maritima, Glaux maritima and Triglochin maritima are constant and varying proportions of these species co-dominate.