FE1D Juncus subnodulosus – Mentha aquatica fen
Vegetation
This community, which lies at the swampy end of the fen vegetation continuum, represents dense stands of the rush Juncus subnodulosus. These patches can have a fairly distinctive orange hue. It is a rather variable assemblage with only one other constant species in the form of the aromatic Mentha aquatica. Frequently the field layer will also contain Phragmites australis, Molinia caerulea, Carex panicea or Galium palustre. There can be a strong tall-herb element in the form of Filipendula ulmaria, Lythrum salicaria, Equisetum spp. or Angelica sylvestris. Beneath the taller vegetation, Hydrocotyle vulgaris or Menyanthes trifoliata can be abundant. The chief bryophyte is Calliergonella cuspidata, but sometimes one may find some Campylium stellatum, Scleropodium purum or Scorpidium scorpioides.
Ecology
This community occurs typically in base-rich fens and flood meadows in the lowlands,
Sub-communities
No sub-communities are described.
Similar communities
The dominance of Juncus subnodulosus should serve to identify this community. Whilst this species can occur in both FE1A and FE1B, the cover of Schoenus and Carex species is much higher in those communities compared with FE1D.
Conservation value
Examples which support ‘brown mosses’ correspond with EU HD Annex I habitat 7230 Alkaline fens. Species diversity is rather poor on average (species/4 m2 = 14.8, n = 30).
Management
Information on the management of these stands is somewhat lacking but it is likely that some are mowed or grazed by livestock. Similar to other fen communities, they are vulnerable to drainage, infilling, reclamation and eutrophication.