SM6B Agrostis stolonifera – Triglochin maritimum grassland
Vegetation
This is a fairly distinctive community dominated by dense swards of Agrostis stolonifera. Other species are each only occasional at best, with the most likely scattered companions being Glaux maritima, Triglochin maritimum, Plantago maritima, Atriplex prostrata, Festuca rubra, Aster tripolium and Juncus gerardii. Mean maximum vegetation height = 50.6 cm, n = 6.
Ecology
This community has predominantly been defined based on data from upper saltmarshes and lagoon margins that are infrequently inundated by saline or brackish water. However, it also provides a home for some inland swards dominated by Agrostis stolonifera. Conditions are circumneutral (mean pH = 7.1, n = 6).
Sub-communities
Two sub-communities are described. The Glaux maritima – Aster tripolium sub-community (SM6Bi) represents coastal saltmarsh swards whilst the Holcus lanatus – Anthoxanthum odoratum sub-community (SM6Bii) represents swards occurring more inland
Similar communities
Nowhere else on the saltmarsh does Agrostis stolonifera tend to achieve such dominance. Inland swards could be confused with the GL2A Agrostis stolonifera – Ranunculus repens marsh-grassland, where Agrostis is also the main species, but that is a more diverse assemblage frequently containing Ranunculus repens, Galium palustre and Filipendula ulmaria.
Conservation value
Almost all coastal examples of this vegetation qualify as EU HD Annex I habitat 1330 Atlantic salt meadows. It is typically a medium richness saltmarsh community (species/4 m2 = 6.9, n = 104) that can support some specialist species.
Management
The main immediate threat to saltmarsh examples of this community is probably grazing by livestock. Sea-level rises as a result of climate change will have an impact, particularly in areas susceptible to coastal squeeze.