|Scientific name||Dryas octopetala – Sesleria caerulea heath|
|Common name||Mountain Avens – Blue Moor-grass heath|
Download full pdf synopsis: HE1A
Dwarf shrub cover in this typically open heath community is provided by Calluna vulgaris and/or low-growing mats of Dryas octopetala. These are accompanied by a range of species characteristic of calcareous grassland. The main graminoids are Sesleria caerulea, Carex flacca and Festuca ovina and there is typically a good diversity of colourful forbs including Succisa pratensis, Thymus polytrichus, Campanula rotundifolia, Linum catharticum, Lotus corniculatus, Viola riviniana/reichenbachiana, Hypericum pulchrum and Geranium sanguineum. The bryophyte layer is composed mainly of Scleropodium purum and Breutelia chrysocoma, with Rhytidiadelphus squarrosus and Rhytidiadelphus triquetrus frequent.
This community occurs mainly in association with karstic limestone pavements and outcrops in the lowlands. Soils are fairly well-drained and more base-rich than those upon which other heath communities grow, but are still quite infertile.
No sub-communities have been described for this community.
From other types of heath with Calluna vulgaris, community HE1A should be easily differentiated by the common presence here of Dryas octopetala and several calcicole species. It will often be found occurring in mosaic with GL3A Briza media – Thymus polytrichus grassland, but in that community the cover of dwarf shrubs is only patchy as best. Overall cover of plants here is higher than that found in the assemblages of open limestone pavement, communities RH1A and RH1B.
This is an exceptionally species-rich heath community. Examples of this vegetation with Dryas octopetala qualify in Ireland as EU Annex I habitat 4060 Alpine and subalpine heath. Other instances, with just Calluna vulgaris, qualify as habitat 4030 Dry heaths.
These heaths are traditionally winter grazed by cattle. The main threats are scrub encroachment, quarrying and destruction of limestone pavement for purposes of agricultural improvement.