|Scientific name||Nardus stricta – Potentilla erecta grassland|
|Common name||Mat-grass – Tormentil grassland|
Download full pdf synopsis: GL4B
The main grasses of this community are Agrostis capillaris, Anthoxanthum odoratum and Nardus stricta, with Festuca ovina and Danthonia decumbens also frequent. They form a fairly low sward. Potentilla erecta and Galium saxatile are constant species, and indeed often the only forbs present apart from Polygala serpyllifolia, which is occasional in the sward. There is generally a well-developed bryophyte layer composed of Hylocomium splendens, Rhytidiadelphus squarrosus, R. loreus, Thuidium tamariscinum and Scleropodium purum. As these grasslands are derived from, and often in mosaic with, dry heaths, there is frequently some low cover of dwarf shrubs in the form of Calluna vulgaris and Vaccinium myrtillus. Carex binervis is frequent and, in more flushed areas, C. panicea can be found amongst the sward.
The Nardus stricta – Potentilla erecta grassland occurs on thin, peaty, very infertile soils and is restricted largely to unenclosed, sheep-grazed, steep slopes in the high uplands. It occurs at higher altitudes than the other grassland communities.
Two sub-communities are described. The Festuca ovina – Luzula campestris sub-community (GL4Bi) represents swards with some mild basic enrichment and consequently the presence of some species more lowland in character. These are somewhat transitional towards community GL4C. The Calluna vulgaris – Rhytidiadelphus loreus sub-community (GL4Bii) is strongly calcifuge in nature and supports a number of species at low abundances that are characteristic of dry and wet heaths.
The most similar community is GL4C Agrostis capillaris – Potentilla erecta grassland. That assemblage occurs on average at lower altitudes and frequently supports a much broader range of forbs including Plantago lanceolata, Succisa pratensis, Prunella vulgaris, Cirsium palustre, Hypochaeris radicata and Lotus corniculatus. From GL4A Agrostis capillaris – Trifolium repens grassland, GL4B differs in the much lower frequency of upland calcifuges.
This is a grassland community of medium species richness. More diverse swards from the uplands may correspond to EU HD Annex I priority habitat 6230 Species-rich Nardus upland grassland*.
These swards are managed as rough grazing land (typically for sheep). The main threats to these grasslands include overgrazing, improvement, abandonment (e.g. bracken or heath encroachment) and afforestation.