Rack Hill

Site of Special Scientific Interest · 51.4848, -2.2259

Condition (Natural England)

Favourable (1)
UnitFeatureConditionArea (ha)Assessed
ST844762 Favourable 10.35 2014-03-12

Geology & landscape

Geological Period: Jurassic · Rock Type: Limestone

Description

Description The best known example in Wiltshire of a lightly grazed Jurassic Limestone sward with a mosaic of grassland scrub transitions supporting a diverse butterfly population. The lightly grazed sward is dominated by upright brome Bromus erectus and tor grass Brachypodium pinnatum. Coarse, relatively species poor, grassland grades into areas of shorter turf with many typical limestone grassland herbs. Dwarf thistle Cirsium acaule, small scabious Scabiosa columbaria, devil's bit scabious Succisa pratensis and common rest-harrow Ononis repens occur widely. More restricted are clustered bellflower Campanula glomerata, purging flax Linum catharticum, yellow wort Blackstonia perfoliata and common centaury Centaurium erythraea. Colonisation by scrub of a range of age classes has reduced the extent of the open grassland, but has created shelter for invertebrates and birds. Typical calcicolous scrub species present include wayfaring tree Viburnum lantana, buckthorn Rhamnus cathartica, spindle Euonymus europaeus and privet Ligustrum vulgare. Gorse Ulex europaeus occurs as several extensive thickets; some of which are recently established. More mature scrub of hawthorn, oak and ash grades into clumps of oak and ash secondary woodland at the north of Rack Hill. More extensive unenclosed woodland at the south of the site, consists of mature planted beech surrounded by self sown natural regeneration of oak, ash and birch. Field maple is present locally along a boundary bank; with scrubby hazel coppice nearby. The ground flora includes dog's mercury Mercurialis perennis, enchanter's nightshade Circaea lutetiana, bluebell Hyacinthoides non-scripta, false brome Brachypodium sylvaticum and a colony of stinking hellebore Helleborus foetidus. The mixture of grassland, scrub and woodland supports a varied butterfly fauna; with more than 20 resident breeding species recently listed. Species of tall grassland and scrub include the marbled white Melanargia galatheaa, green hairstreak Callophrys rubi and dark green fritillary Argynnis aglaja. More shade tolerant butterflies are represented by the speckled wood Lasiommata megera, ringlet Aphantopus hyperantus and comma Polygonia c album.

Species mentioned

English name
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Latin name
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IUCN / Red List Type Family
ringlet Aphantopus hyperantus LC butterfly nymphalidae
dark green fritillary Argynnis aglaja Not listed in GB list butterfly nymphalidae
green hairstreak Callophrys rubi LC butterfly lycaenidae
wall Lasiommata megera EN butterfly nymphalidae
tor grass Brachypodium pinnatum LC grass poaceae
wood false brome Brachypodium sylvaticum LC grass poaceae
upright brome Bromus erectus Not listed in GB list grass poaceae
yellowwort Blackstonia perfoliata LC herb gentianaceae
clustered bellflower Campanula glomerata VU herb campanulaceae
common centuary Centaurium erythraea LC herb gentianaceae
enchanter's nightshade Circaea lutetiana LC herb onagraceae
dwarf thistle Cirsium acaule VU herb asteraceae
foetid hellebore Helleborus foetidus LC herb ranunculaceae
bluebell Hyacinthoides non-scripta LC herb liliaceae
fairy flax Linum catharticum LC herb linaceae
dog's mercury Mercurialis perennis LC herb euphorbiaceae
common rest-harrow Ononis repens VU herb fabaceae
small scabious Scabiosa columbaria LC herb caprifoliaceae
devils-bit scabious Succisa pratensis VU herb caprifoliaceae
spindle tree Euonymus europaeus LC shrub celastraceae
wild privet Ligustrum vulgare LC shrub oleaceae
buckthorn Rhamnus cathartica LC shrub rhamnaceae
gorse Ulex europaeus LC shrub leguminosae
wayfaring tree Viburnum lantana LC shrub caprifoliaceae

Insects to look out for

These moths, butterflies and beetles are known to feed on plants recorded at this site, and carry a notable UK conservation status — but a host-plant being present doesn't mean the insect has actually been recorded here. Treat this as "worth watching for," not a confirmed sighting.

SpeciesStatusVia host-plant
Straw belle
Aspitates gilvaria
Endangered Linum catharticum
Chequered skipper
Carterocephalus palaemon
Endangered Brachypodium sylvaticum
The lappet
Gastropacha quercifolia
Endangered Rhamnus cathartica
The sprawler
Asteroscopus sphinx
Vulnerable Viburnum lantana
Marsh fritillary
Euphydryas aurinia
Vulnerable Scabiosa columbaria, Succisa pratensis
Grayling
Hipparchia semele
Vulnerable Brachypodium sylvaticum
Pale brindled
Phigalia pilosaria
Vulnerable Rhamnus cathartica
Silver studded blue
Plebejus argus
Vulnerable Ononis spp., Ulex spp.
Lead belle
Scotopteryx mucronata
Vulnerable Ulex europaeus
Rest harrow
Aplasta ononaria
Near Threatened Ononis repens
Autumnal rustic
Eugnorisma glareosa
Near Threatened Hyacinthoides non-scripta
Wall
Lasiommata megera
Near Threatened Brachypodium sylvaticum

Host-plant data: Cook et al. (2025), Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2024, UK Centre for Ecology & Hydrology / Butterfly Conservation; and Padovani et al. (2020), Database of Insects and their Food Plants (DBIF), UK Centre for Ecology & Hydrology (both Open Government Licence). Contains data supplied by UK Centre for Ecology & Hydrology.

Plant communities

W21 — Hedgerow scrub, Mixed scrub

Crataegus monogyna-Hedera helix scrub

Matches 9 species from the description above: Brachypodium pinnatum, Brachypodium sylvaticum, Circaea lutetiana, Euonymus europaeus, Hyacinthoides non-scripta, Ligustrum vulgare, Mercurialis perennis, Rhamnus cathartica, Viburnum lantana

Hedera helix, Salix cinerea, Acer pseudoplatanus, Ilex aquifolium, Betula pendula, Corylus avellana, Fagus sylvatica, Quercus robur, Fraxinus excelsior, Malus sylvestris, Sorbus aria, Taxus baccata, Ulmus glabra, Ulmus procera, Sambucus nigra, Viburnum lantana, Euonymus europaeus, Cornus sanguinea, Juniperus communis, Ligustrum vulgare, Clematis vitalba, Rhamnus cathartica, Crataegus laevigata, Crataegus monogyna, Prunus spinosa, Juncus effusus, Plagiomnium undulatum, Brachythecium rutabulum, Kindbergia praelonga, Rhynchostegium confertum, Tamus communis, Heracleum sphondylium, Torilis japonica, Arum maculatum, Arctium minus, Cirsium arvense, Lonicera periclymenum, Moehringia trinervia, Silene dioica, Stellaria graminea, Stellaria holostea, Stellaria media agg., Calystegia sepium, Mercurialis perennis, Geranium robertianum, Iris foetidissima, Glechoma hederacea, Lamium purpureum, Origanum vulgare, Stachys sylvatica, Teucrium scorodonia, Allium ursinum, Hyacinthoides non-scripta, Circaea lutetiana, Rumex sanguineus, Anemone nemorosa, Ranunculus repens, Fragaria vesca, Geum urbanum, Potentilla sterilis, Poterium sanguisorba, Rosa arvensis, Rosa canina, Rubia peregrina, Rubus fruticosus agg., Galium aparine, Urtica dioica, Viola riviniana, Anisantha sterilis, Arrhenatherum elatius, Brachypodium pinnatum, Brachypodium sylvaticum, Bromopsis erecta, Dactylis glomerata, Elytrigia repens, Holcus lanatus, Holcus mollis, Poa trivialis, Asplenium scolopendrium, Pteridium aquilinum, Dryopteris filix-mas

W22 — Hedgerow scrub, Mixed scrub

Prunus spinosa-Rubus fruticosus scrub

Matches 4 species from the description above: Brachypodium sylvaticum, Hyacinthoides non-scripta, Mercurialis perennis, Ulex europaeus

Hedera helix, Acer campestre, Corylus avellana, Ulex europaeus, Prunus spinosa, Plagiomnium undulatum, Brachythecium rutabulum, Eurhynchium striatum, Kindbergia praelonga, Thuidium tamariscinum, Atrichum undulatum, Lophocolea bidentata, Achillea millefolium, Cardamine flexuosa, Lonicera periclymenum, Moehringia trinervia, Silene dioica, Silene uniflora, Stellaria media agg., Mercurialis perennis, Geranium robertianum, Stachys sylvatica, Teucrium scorodonia, Hyacinthoides non-scripta, Oxalis acetosella, Digitalis purpurea, Plantago lanceolata, Veronica chamaedrys, Armeria maritima, Rumex acetosa, Filipendula ulmaria, Geum urbanum, Rosa canina, Rubus fruticosus agg., Rubus idaeus, Galium aparine, Urtica dioica, Viola riviniana, Agrostis capillaris, Brachypodium sylvaticum, Dactylis glomerata, Festuca rubra, Holcus lanatus, Holcus mollis, Poa trivialis, Asplenium scolopendrium, Pteridium aquilinum, Dryopteris borreri, Dryopteris filix-mas

W20 — Montane scrub

Salix lapponum-Luzula sylvatica scrub

Matches 1 species from the description above: Succisa pratensis

Salix arbuscula, Salix cinerea, Salix lapponum, Salix myrsinites, Salix phylicifolia, Salix reticulata, Empetrum nigrum, Calluna vulgaris, Salix lanata, Vaccinium myrtillus, Vaccinium uliginosum, Carex atrata, Carex bigelowii, Carex binervis, Carex flacca, Luzula multiflora, Luzula sylvatica, Huperzia selago, Selaginella selaginoides, Aulacomnium palustre, Mnium hornum, Philonotis fontana, Plagiomnium undulatum, Rhizomnium punctatum, Dicranum bonjeanii, Dicranum majus, Dicranum scoparium, Fissidens adianthoides, Racomitrium lanuginosum, Calliergonell cuspidatum, Ctenidium molluscum, Hylocomium splendens, Hypnum callichroum, Hypnum cupressiforme, Palustriella commutatum, Plagiothecium denticulatum, Plagiothecium undulatum, Pleurozium schreberi, Ptilium crista-castrensis, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Rhytidiadelphus triquetrus, Sanionia uncinata, Scorpidium revolvens, Thuidium tamariscinum, Atrichum undulatum, Polytrichastrum alpinum, Sphagnum capillifolium, Sphagnum fallax, Sphagnum girgensohnii, Sphagnum palustre, Sphagnum russowii, Sphagnum squarrosum, Sphagnum subnitens, Sphagnum teres, Barbilophozia barbata, Chiloscyphus polyanthos, Diplophyllum albicans, Lophocolea bidentata, Plagiochila porelloides, Ptilidium ciliare, Scapania undulata, Cladonia squamosa, Peltigera canina, Angelica sylvestris, Caltha palustris, Hieraclium spp., Saussurea alpina, Solidago virgaurea, Campanula rotundifolia, Succisa pratensis, Valeriana officinalis, Rhodiola rosea, Vaccinium vitis-idaea, Thymus praecox, Epilobium anagallidifolium, Dactylorhiza viridis, Euphrasia officinalis, Rhinanthus minor, Oxalis acetosella, Oxyria digyna, Polygonum viviparum, Rumex acetosa, Anemone nemorosa, Ranunculus acris, Thalictrum alpinum, Alchemilla alpina, Alchemilla glabra, Filipendula ulmaria, Geum rivale, Galium boreale, Galium saxatile, Saxifraga aizoides, Saxifraga hypnoides, Saxifraga oppositifolia, Saxifraga stellaris, Viola riviniana, Agrostis canina, Agrostis capillaris, Anthoxanthum odoratum, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Nardus stricta, Dryopteris dilatata, Phegopteris connectilis