Salisbury Plain

Salisbury Plain is a chalk plateau in the south western part of central southern England covering . It is part of a system of chalk downlands throughout eastern and southern England formed by the rocks of the Chalk Group and largely lies within the county of Wiltshire, but stretches into Hampshire.

The plain is famous for its rich archaeology, including Stonehenge, one of England's best known landmarks. Large areas are given over to military training and thus the sparsely populated plain is the biggest remaining area of calcareous grassland in northwest Europe. Additionally the plain has arable land, and a few small areas of beech trees and coniferous woodland. Its highest point is Easton Hill.

Physical geography

The boundaries of Salisbury Plain have never been truly defined, and there is some difference of opinion as to its exact area. The river valleys surrounding it, and other downs and plains beyond them loosely define its boundaries. To the north the scarp of the downs overlooks the Vale of Pewsey, and to the northwest the Bristol Avon. The River Wylye runs along the southwest, and the Bourne runs to the east.English Nature Salisbury Plain SSSI citation
The Hampshire Avon runs through the eastern half of the plain, and to the south the plain peters out as the river valleys close together before meeting at Salisbury. From here the Avon continues south to the English Channel at Christchurch. The Hampshire Downs and the Berkshire Downs are chalk downland to the east and north of Salisbury Plain, and the Dorset Downs and Cranborne Chase are to the southwest. In the west and north west the geology is mainly the clays and limestones of the Blackmore Vale, Avon Vale and Vale of Wardour. The Mendip Hills rise to the west of Salisbury Plain, and the Cotswolds to the north west.

Amesbury is considered the largest settlement on the plain (southern fringes), though there are a number of small villages, such as Tilshead, Chitterne and Shrewton in the middle of the plain, as well as various hamlets and army camps. The A303 road runs through the southern area of the plain, while the A345 and the A360 cut across the centre.

History

Salisbury Plain is famous for its history and archaeology. In the Neolithic period, Stone Age people began to settle on the plain, most likely centred around the causewayed enclosure of Robin Hood's Ball. Large long barrows such as White Barrow and other earthworks were built across the plain. By 2500 BC areas around Durrington Walls and Stonehenge had become a focus for building, and the southern part of the plain continued to be settled into the Bronze Age.

Around 600 BC, Iron Age hillforts came to be constructed around the boundaries of the plain, including Scratchbury Camp and Battlesbury Camp to the southwest, Bratton Camp to the northwest, Casterley Camp to the north, Yarnbury and Vespasian's Camp to the south, and Sidbury Hill to the east.

Roman roads are visible features, probably serving a settlement near Old Sarum. Villas are sparse, however, and Anglo-Saxon place names suggest that the plain was mostly a grain-producing imperial estate.

In the 6th century, Anglo-Saxon incomers built planned settlements in the valleys surrounded by strip lynchets, with the downland left as sheep pasture. To the south is the city of Salisbury, whose 13th and 14th century cathedral is famous for having the tallest spire in the country, and the building was, for many centuries, the tallest building in Britain. The cathedral is evidence of the prosperity the wool and cloth trade brought to the area. In the mid-19th century the wool and cloth industry began to decline, leading to a decline in the population and change in land use from sheep farming to agriculture and military use. Wiltshire became one of the poorest counties in England during this period of decline.

There are a number of chalk carvings on the plain, of which the most famous is the Westbury White Horse. The Kennet and Avon Canal was constructed to the north of the plain, through the Vale of Pewsey.

In September 1896, George Kemp and Guglielmo Marconi experimented with wireless telegraphy on Salisbury Plain, and achieved good results over a distance of .

Military use

The military training area covers roughly half of the plain (and makes up about 11% of Wiltshire). The army first conducted exercises on the plain in 1898. From that time, the Ministry of Defence bought up large areas of land until the Second World War. The MoD now own of land, making it the largest military training area in the United Kingdom. Much of this land is let to farmers or grazed under licence, while around (12,000 ha) are used for live firing, where public access is greatly restricted or permanently closed. The land and facilities are managed by the MoD's Defence Infrastructure Organisation.

The largest camps and barracks are at Larkhill, Bulford, Tidworth, Trenchard Lines (Upavon) and Waterloo Lines (Warminster). Copehill Down is an urban warfare training site. Several installations have been built and since removed, including a railway line and aerodrome that were constructed next to Stonehenge. A grass aerodrome at Netheravon was used by the RAF until 1963, then by the Army Air Corps until 2012, and now as a tri-service installation.

The Royal School of Artillery has been based at Larkhill since 1915, and live firing is conducted on the plain for approximately 340 days of each year. Military personnel from the UK and around the world spend some 600,000-man days on the plain every year.

In 1943, the village of Imber and the hamlet of Hinton Parva were evacuated to allow training for Operation Overlord to be conducted. Whilst the inhabitants of Hinton Parva were allowed to return at the end of hostilities, Imber village has remained closed, except for an annual church service and some bank holidays. Roads in the Imber area are also closed, as they lie within the Imber Range live firing area; it is possible to walk all of the perimeter of the range on public footpaths.

The training area is close to other military facilities including the Defence Science and Technology Laboratory at Porton Down (much of whose work is secret), Boscombe Down airfield and Middle Wallop Army Air Corps Base in Hampshire, where pilots train on the Westland Apache.

20,000 hectares are designated Sites of Special Scientific Interest and Special Areas of Conservation, and the entire SP is a Special Protection Area for birds.

BFBS Radio broadcasts from studios on Marlborough Road, Bulford, on DAB, FM and satellite channels.

Ecology

Because of the large training areas inaccessible to the public, the plain is a wildlife haven, and home to two national nature reserves, but there is concern that the low level of grazing on the plain could allow scrub to encroach on the grassland. The plain supports the largest known expanse of unimproved chalk downland in north west Europe, and represents 41% of Britain's remaining area of this wildlife habitat. The plain supports 13 species of nationally rare and scarce plants, 67 species of rare and scarce invertebrates and forms a site of international importance for birds. In addition to chalk downland, the plain supports scrub and woodland habitats, temporary and permanent pools and the River Bourne.

Vegetation

A diversity of soil types, slope, aspect and past and present land-use has given rise to various grassland communities. Historical evidence suggests that large areas of grassland are of great antiquity, and areas which were cultivated at the beginning of the 20th century have experienced nearly 100 years of chalk grassland re-colonisation. Parts of East Salisbury Plain and the periphery of Central and West comprise areas of grassland currently managed for grazing pasture and hay-cutting, whilst the middle of Centre and West are ungrazed. A large proportion of Salisbury Plain supports upright brome (''Bromus erectus'') species-rich grassland, within which a continuous floristic variation is seen. A widespread type on the plain is characterised by an abundance of red fescue (''Festuca rubra''), crested hair-grass (''Koeleria macrantha''), salad burnet (''Sanguisorba minor''), lady's bedstraw (''Galium verum''), rough hawkbit (''Leontodon hispidus''), common rock-rose (''Helianthemum nummularium'') and dropwort ('' Filipendula vulgaris''). The high constancy of this last species is a distinctive feature of the upright brome grasslands on Salisbury Plain and is otherwise only known from one other site in Hampshire. Where upright brome is less dominating, plants such as small scabiosa (''Scabiosa columbaria''), clustered bellflower (''Campanula glomerata''), dyer's greenweed (''Genista tinctoria''), kidney vetch (''Anthyllis vulneraria''), sainfoin (''Onobrychis viciifolia'') and horseshoe vetch (''Hippocrepis comosa'') are characteristic associates.

The rare and notable plants which occur here include burnt-tip orchid (''Neotinea ustulata''), slender bedstraw (''Galium pumilum''), field fleawort (''Senecio integrifolius'') and the nationally scarce British endemic early gentian (''Gentianella anglica''). Particularly associated with long established turf on thin rendzina soils, and rabbit-grazed areas of the eastern and central ranges, are low-growing perennials including squinancy-wort (''Asperula cynanchica''), chalk milkwort (''Polygala calcarea''), dwarf thistle (''Cirsium acaule''), wild thyme (''Thymus praecox''), the nationally scarce bastard toadflax