Banc Hirllwyn
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Habitats
Geology & landscape
Geological Period: Ordovician
Landscape processes: Volcanic / Igneous
Description
Description Banc Hirllwyn is of special interest for its areas of acid grassland vegetation and the nationally scarce maiden pink Dianthus deltoides. The site is situated 1km to the north-west of the village of Hundred House at an altitude of 300 m. It occupies a prominent ridge of volcanic rocks which forms part of the Llandrindod Wells Ordovician inlier. Shallow soils over rock outcrops support stands of acid grassland along the south and south-east facing slopes of the bank. The grassland is prone to drought during the summer months, and has a high proportion of annual plants adapted to survive such conditions. The main grasses in the short, open sward are sheep’s fescue Festuca ovina, common bent Agrostis capillaris, early hair-grass Aira praecox and squirrel-tail fescue Vulpia bromoides. Common associates include sheep’s sorrel Rumex acetosella, common mouse-ear Cerastium fontanum, parsley piert Aphanes arvensis, wall speedwell Veronica arvensis, common bird’s-foot-trefoil Lotus corniculatus, lady’s bedstraw Galium verum, spring sedge Carex caryophyllea, the uncommon upright chickweed Moenchia erecta, wild thyme Thymus polytrichus, the mosses Dicranum scoparium, Brachythecium albicans and Hypnum cupressiforme and the lichens Peltigera rufescens and Cladonia spp.. Other locally frequent components of the vegetation include dove’s-foot cranesbill Geranium molle, yarrow Achillea millefolium, harebell Campanula rotundifolia, tormentil Potentilla erecta, carline thistle Carlina vulgaris and the nationally scarce maiden pink and lichen Peltigera canina. The locally scarce annual knawel Scleranthus annuus has also been recorded at the site. Small rock outcrops within the site support mosses, such as Hedwigia sp. and a variety of lichens, including Rhizocarpon viridiatrum, Porpidia cinereoatra and the locally uncommon Caloplaca arenaria, Caloplaca ceracea and Porpidia platycarpoides. The lower flanks of the bank support open oak Quercus spp. woodland, which provides additional interest. The acid grassland extends under the tree canopy in places and intergrades with species-poor neutral grassland on the deeper soils of the plateau top. This area has been subject to past agricultural improvement but is now reverting to a more natural state.
Species mentioned
Show the 28 species mentioned in the description, with red-list statusPlant communities
M25 — Blanket bog, Coastal floodplain grazing marsh, Lowland fen, Purple moor grass and rush pasture, Upland acid grassland
Molinia caerulea-Potentilla erecta mire
Show 85 indicator speciesSalix cinerea, Calluna vulgaris, Erica tetralix, Myrica gale, Vaccinium oxycoccos, Ulex europaeus, Ulex gallii, Carex echinata, Carex flacca, Carex nigra, Carex panicea, Eriophorum angustifolium, Schoenus nigricans, Juncus acutiflorus, Juncus articulatus, Juncus effusus, Juncus subnodulosus, Luzula campestris, Luzula multiflora, Aulacomnium palustre, Pohlia nutans, Calliergon giganteum, Calliergonell cuspidatum, Hypnum jutlandicum, Kindbergia praelonga, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus squarrosus, Polytrichum commune, Sphagnum auriculatum, Sphagnum capillifolium, Sphagnum fallax, Sphagnum palustre, Sphagnum papillosum, Sphagnum subnitens, Calypogeia fissa, Cephalozia bicuspidata, Lophocolea bidentata, Lophozia ventricosa, Angelica sylvestris, Carum verticillatum, Hydrocotyle vulgaris, Achillea ptarmica, Centaurea nigra, Cirsium palustre, Eupatorium cannabinum, Pulicaria dysenterica, Serratula tinctoria, Cardamine pratensis, Lobelia urens, Succisa pratensis, Valeriana officinalis, Equisetum palustre, Lotus pedunculatus, Hypericum pulchrum, Hypericum tetrapterum, Mentha aquatica, Scutellaria minor, Menyanthes trifoliata, Narthecium ossifragum, Epilobium palustre, Dactylorhiza maculata, Rumex acetosa, Ranunculus acris, Ranunculus flammula, Filipendula ulmaria, Potentilla erecta, Rubus fruticosus agg., Galium palustre, Viola palustris, Agrostis canina, Agrostis capillaris, Agrostis curtisii, Agrostis stolonifera, Anthoxanthum odoratum, Danthonia decumbens, Deschampsia cespitosa, Festuca ovina, Festuca rubra, Holcus lanatus, Molinia caerulea, Nardus stricta, Phragmites australis, Dryopteris carthusiana, Osmunda regalis
U2 — Brownfield, Lowland dry acid grassland, Upland acid grassland
Deschampsia flexuosa grassland
Show 40 indicator speciesBetula pendula, Quercus hybrid, Empetrum nigrum subsp.nigrum, Calluna vulgaris, Vaccinium myrtillus, Ulex europaeus, Carex nigra, Eriophorum vaginatum, Juncus effusus, Juncus squarrosus, Luzula multiflora, Orthodontium lineare, Pohlia nutans, Campylopus pyriformis, Dicranum scoparium, Hypnum cupressiforme, Plagiothecium undulatum, Pleurozium schreberi, Rhytidiadelphus squarrosus, Polytrichum commune, Polytrichum piliferum, Barbilophozia floerkei, Cladonia gracilis, Chamerion angustifolium, Rumex acetosa, Rumex acetosella, Potentilla erecta, Rubus fruticosus agg., Galium saxatile, Agrostis capillaris, Agrostis vinealis, Anthoxanthum odoratum, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Holcus mollis, Molinia caerulea, Nardus stricta, Poa annua, Pteridium aquilinum
U3 — Lowland dry acid grassland, Upland acid grassland
Agrostis curtisii grassland
Show 34 indicator speciesCalluna vulgaris, Erica cinerea, Erica tetralix, Vaccinium myrtillus, Ulex europaeus, Ulex gallii, Carex binervis, Carex panicea, Carex pilulifera, Luzula campestris, Dicranum scoparium, Hylocomium splendens, Hypnum cupressiforme, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus squarrosus, Cladonia floerkeana, Cladonia impexa, Hypochaeris radicata, Teucrium scorodonia, Polygala serpyllifolia, Potentilla erecta, Galium saxatile, Agrostis capillaris, Agrostis curtisii, Agrostis vinealis, Anthoxanthum odoratum, Danthonia decumbens, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Molinia caerulea, Nardus stricta, Pteridium aquilinum
U4 — Lowland dry acid grassland, Upland acid grassland, Upland calcareous grassland
Festuca ovina-Agrostis capillaris-Galium saxatile grassland
Show 82 indicator speciesCalluna vulgaris, Vaccinium myrtillus, Carex binervis, Carex caryophyllea, Carex echinata, Carex nigra, Carex panicea, Carex pilulifera, Juncus effusus, Juncus squarrosus, Luzula campestris, Luzula multiflora, Luzula sylvatica, Mnium hornum, Dicranum scoparium, Racomitrium lanuginosum, Hylocomium splendens, Hypnum cupressiforme, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Rhytidiadelphus triquetrus, Thuidium tamariscinum, Polytrichastrum alpinum, Polytrichum commune, Lophocolea bidentata, Conopodium majus, Achillea millefolium, Bellis perennis, Cirsium arvense, Cirsium vulgare, Taraxacum officianalis, Campanula rotundifolia, Succisa pratensis, Cerastium fontanum, Lathyrus montanus, Lotus corniculatus, Trifolium pratense, Trifolium repens, Thymus praecox, Euphrasia officinalis, Oxalis acetosella, Plantago lanceolata, Veronica chamaedrys, Veronica officinalis, Polygala serpyllifolia, Rumex acetosa, Primula vulgaris, Anemone nemorosa, Ranunculus acris, Ranunculus repens, Potentilla erecta, Poterium sanguisorba, Galium saxatile, Galium verum, Viola lutea, Viola palustris, Viola riviniana, Agrostis canina, Agrostis capillaris, Alopecurus pratensis, Anthoxanthum odoratum, Avenula pratensis, Briza media, Cynosurus cristatus, Dactylis glomerata, Danthonia decumbens, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Holcus lanatus, Holcus mollis, Lolium perenne, Molinia caerulea, Nardus stricta, Poa annua, Poa pratensis, Blechnum spicant, Pteridium aquilinum, Chara curta
U5 — Upland acid grassland, Upland calcareous grassland
Nardus stricta-Galium saxatile grassland
Show 79 indicator speciesEmpetrum nigrum subsp.nigrum, Calluna vulgaris, Erica cinerea, Erica tetralix, Vaccinium myrtillus, Carex bigelowii, Carex binervis, Carex demissa, Carex nigra, Carex panicea, Carex pilulifera, Carex pulicaris, Eriophorum angustifolium, Eriophorum vaginatum, Trichophorum cespitosum, Juncus effusus, Juncus squarrosus, Luzula campestris, Luzula multiflora, Luzula sylvatica, Huperzia selago, Selaginella selaginoides, Aulacomnium palustre, Pohlia nutans, Campylopus flexuosus, Dicranella heteromalla, Dicranum scoparium, Racomitrium lanuginosum, Calliergonell cuspidatum, Hylocomium splendens, Hypnum cupressiforme, Plagiothecium undulatum, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Thuidium tamariscinum, Polytrichastrum alpinum, Polytrichum commune, Polytrichum formosum, Polytrichum juniperinum, Sphagnum papillosum, Barbilophozia floerkei, Calypogeia muelleriana, Diplophyllum albicans, Lophocolea bidentata, Lophozia ventricosa, Pleurozia purpurea, Ptilidium ciliare, Scapania gracilis, Cetraria islandica, Cladonia uncialis, Cirsium palustre, Scorzoneroides autumnalis, Campanula rotundifolia, Cerastium fontanum, Equisetum palustre, Vaccinium vitis-idaea, Trifolium repens, Narthecium ossifragum, Plantago lanceolata, Polygala serpyllifolia, Anemone nemorosa, Ranunculus acris, Alchemilla alpina, Potentilla erecta, Galium saxatile, Viola riviniana, Agrostis capillaris, Agrostis vinealis, Anthoxanthum odoratum, Danthonia decumbens, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Molinia caerulea, Nardus stricta, Blechnum spicant