HE3E Racomitrium lanuginosum – Festuca vivipara heath
Vegetation
This is a low-growing, rather sparsely vegetated community with Racomitrium lanuginosum often the only plentiful species. Growing alongside the mounds of this moss are usually found stems of Vaccinium myrtillus and a few tufts of Agrostis capillaris and Festuca vivipara together with some prostrate shoots of Galium saxatile. There is frequently some small cover of Calluna vulgaris and Deschampsia flexuosa. The other typical members of the bryophyte layer are Hypnum jutlandicum, Diplophyllum albicans, Rhytidiadelphus loreus, Scapania gracilis and Hylocomium splendens, but acrocarpous mosses such as Polytrichum alpinum, Dicranum scoparium and Dicranella heteromalla are also frequent. Occasionally one will find here patches of Herbertus aduncus or Carex bigelowii.
Ecology
This is a heath community of the highest mountain slopes, saddles, ridges and plateaux (mean altitude = 696 m, n = 109; mean slope = 21.1°, n = 108) where there is high exposure. The substrate is usually very rocky with thin, acidic and infertile soils (mean extent of bare rock = 24.2%, n = 108).
Sub-communities
Two sub-communities have been described. The Hymenophyllum wilsonii – Bazzania tricrenata subcommunity (HE3Ei) is a liverwort-rich variant with Scapania gracilis, Pleurozia purpurea, Bazzania tricrenata and Herbertus aduncus all constant and Plagiochila spinulosa frequent. The other sub-community lacks any particular indicators and is referred to as the typical sub-community (HE3Eii).
Similar communities
A similar community is the HE3D Calluna vulgaris – Racomitrium lanuginosum heath which also occurs on exposed ground in the mountains. That community, however, tends to occur at slightly lower altitudes, with Calluna vulgaris much more abundant. The RH4F Festuca vivipara – Oligotrichum hercynicum fellfield differs in the lower cover of Racomitrium species and the typical absence of dwarf shrubs and pleurocarpous mosses.
Conservation value
Most examples of this vegetation qualify as EU HD Annex I habitat 4060 Alpine and subalpine heath. Others, particularly those which support arctic-alpine species, may correspond with habitat 6150 Siliceous alpine and boreal grasslands. This is on average a species-rich heath community (species/4 m2 = 22.5, n = 103).
Management
These heaths, which often form parts of commonages, may be used as rough grazing land (typically for sheep) and overgrazing can be a problem. Climate change threatens arctic-alpine species which are restricted to montane communities such as this.