Portsdown

Site of Special Scientific Interest · 50.8549, -1.0915

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Hampshire County

Condition (Natural England)

Favourable (1) Unfavourable Recovering (5)
UnitFeatureConditionArea (ha)Assessed
SU620067 — Favourable 6.35 2021-07-14
SU628066 — Unfavourable Recovering 1.96 2021-07-14
SU630066 — Unfavourable Recovering 20.2 2021-07-14
SU632065 — Unfavourable Recovering 1.18 2021-07-14
SU644065 — Unfavourable Recovering 19.68 2021-07-14
SU656063 — Unfavourable Recovering 17.98 2021-07-14

Habitats

Mixed scrub, Montane scrub

Geology & landscape

Rock Type: Chalk

Description

Area, 80.67 hectares 199.36 ac Description Portsdown is an isolated east west chalk anticline with a long south facing escarpment which remains un reclaimed. On the lower south facing slopes raised beaches mark former sea levels and it is postulated that former wave erosion has removed the Tertiary deposits and some of the chalk, leaving very steep slopes. Despite the absence of grazing and extensive disturbance, these slopes still support a rich chalk grassland flora and a rich and diverse insect fauna. hawthorn Crataegus monogyna scrub is extensive and much of the grassland is dominated by upright brome Bromus erectus, a tall vigorous species which responds rapidly to lack of grazing. Areas of finer turf dominated by red rescue Festuca rubra, sheep's fescue Festuca ovina and a wide range of small herbs, remains widespread, however, whilst the site supports a number of species of limited distribution, including hairy rock cress Arabis hirsuta, pale flax Linum bienne, meadow cranesbill Geranium pratense, horseshoe vetch Hippocrepis comosa, bastard toadflax Thesium humifosum, early gentian Gentianella anglica, knapweed broomrape Orobanche elatior, bee orchid Ophrys apifera and fly orchid Ophrys insectifera. The insect fauna has been studied in detail and includes a comprehensive range of chalk downland butterflies Lepidoptera, beetles Coleoptera, bees and allied insects Hymenoptera. Of interest is the occurrence in an atypical habitat of the bush cricket Conocephalus fuscus and a substantial population of the largest of the British bush crickets Tettigonia viridissima.

Species mentioned

English name
search for this in other sites		 Latin name
search with Google		 IUCN / Red List Type Family
long-winged conehead Conocephalus fuscus LC bush cricket tettigoniidae
great green bush-cricket Tettigonia viridissima LC bush cricket tettigoniidae
upright brome Bromus erectus Not listed in GB list grass poaceae
sheep's fescue Festuca ovina LC grass poaceae
red fescue Festuca rubra LC grass poaceae
hairy rockcress Arabis hirsuta VU herb brassicaceae
early gentian Gentianella anglica Not listed in GB list herb gentianaceae
meadow cranesbill Geranium pratense LC herb geraniaceae
horseshoe vetch Hippocrepis comosa VU herb fabaceae
pale flax Linum bienne LC herb linaceae
bee orchid Ophrys apifera LC herb orchidaceae
fly orchid Ophrys insectifera VU herb orchidaceae
tall broomrape Orobanche elatior LC herb orobanchaceae
hawthorn Crataegus monogyna LC shrub rosaceae

Plant communities

W20 — Montane scrub

Salix lapponum-Luzula sylvatica scrub

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

W21 — Hedgerow scrub, Mixed scrub

Crataegus monogyna-Hedera helix scrub

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

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