Long Knoll
Condition (Natural England)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| ST785377 | — | Favourable | 4.27 | 2012-07-23 |
| ST787375 | — | Favourable | 8.03 | 2012-07-23 |
| ST796375 | — | Unfavourable Recovering | 13.8 | 2012-06-29 |
| ST796377 | — | Unfavourable Recovering | 8.42 | 2012-06-29 |
Habitats
Geology & landscape
Rock Type: Chalk
Landscape processes: Karst
Birds & fish recorded
Birds
| Species | Season |
|---|---|
| buzzard | Unknown |
Description
Description Long Knoll is the most westerly area of chalk grassland in Wiltshire. It encompasses a number of botanically diverse grassland communities and supports several plant species which are particularly associated with the western chalklands of Britain. Nationally, the extent of chalk grassland has greatly declined as a result of modern agricultural intensification; this site is one of the remaining herb rich examples. Predominantly on Middle Chalk, Long Knoll forms a prominent feature on the surrounding Lower Chalk plain. It is an outlying remnant of a chalk plateau which once spread further to the west and its smooth convex shape is considered to represent erosion from very uniform deposits. Rising some 60 metres high, the knoll forms a ridge running east west for one and a half kilomtres. The SSSI includes some 80 percent of the ridge and the steep grassland slopes face almost exclusively to the south and north. Differences in aspect and grazing regime have had a marked influence on the plant communities. The majority of the south facing slope is lightly grazed and is characterised by a mosaic of short and long vegetation. The shorter turf supports an intermix of grasses, sedges and herbs with up to 31 species in a square metre. Here, glaucous sedge Carex flacca, sheep's fescue Festuca ovina, meadow oat grass Avenula pratensis and quaking grass Briza mediare common, together with cowslip Primula veris, rock rose Helianthemum nummularium, small scabious Scabiosa columbaria and salad burnet Poterium sanguisorba. Some of the less common chalk grassland herbs include clustered bellflower Campanula glomerata, early purple orchid Orchis mascula, horseshoe vetch Hippocrepis comosa, kidney vetch Anthyllis vulneraria and chalk milkwort Polygala calcarea. Species present which are characteristic of the western chalk grasslands include heath grass Danthonia decumbens, betony Betonica officinalis and devil's bit scabious Succisa pratensis. The areas of longer vegetation are dominated by upright brome Bromus erectus but both tall fescue Schedonorus arundinaceus and downy oat grass Avenula pubescens are significant components. The species composition of the north facing slopes is somewhat different, due in part to the effect of aspect. The turf has a high bryophyte content with mosses such as Rhytidiadelphus squarrosus and Pseudoscleropodium purum occurring widely and the frequent occurrence of tufted hair grass Deschampsia cespitosa and common valerian Valeriana officinalis on chalk soils is of particular interest. Light grazing in the westernmost grazing compartment has led to an abundance of downy oat grass and false oat grass Arrhenatherum elatius while the remaining well grazed section supports frequent red fescue Festuca rubra and crested hairgrass Koeleria macrantha. Herbs are widespread in both compartments and include autumn gentian Gentianella amarella and plentiful devil's bit scabious and fairy flax Linum catharticum. Small areas of scattered scrub occur; these are predominantly hawthorn but with some ash and elder. There has been limited faunal recording but the scrub is attractive to linnet and yellowhammer and both buzzard and green woodpecker use the downland area for feeding. The site supports populations of many grassland butterflies including common blue, brown argus and marbled white. Hare and badger are amongst the mammals recorded.
Species mentioned
Show the 31 species mentioned in the description, with red-list statusPlant communities
W20 — Montane scrub
Salix lapponum-Luzula sylvatica scrub
Show 107 indicator speciesSalix 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
Show 81 indicator speciesHedera 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
Show 49 indicator speciesHedera 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