Porton Down IPA
Location: East of the village of Porton, between the A338 and A30, north east of Salisbury in Wiltshire.
Grid Reference: SU 218 359
Porton Down is an extensive area of grassland, scrub and woodland on the Wiltshire-Hampshire border.The site is famous as the location of the Defence and Science Technology Laboratory and also preserves archaeologically significant features.Due to its military use, the area has remained largely unchanged over recent decades. It is now one of the largest uninterrupted tracts of semi-natural chalk grasslands containing outstanding populations of uncommon plants. Over the last 50 years, agricultural intensification has led to this habitat declining by 80% UK wide.
A diverse range of invertebrates can be found with an obvious feature being an estimated three million anthills. The habitat supports downland breeding birds, including hobby, buzzard and long-eared owl and important numbers of stone curlews.
Four types of grassland have been found in the area with two of these being particularly rare.A community of red fescue and downy oatgrass form tussocks and this is virtually unique to Porton Down. A second rare community is made up of sheep’s fescue, mouse-ear hawkweed and wild thyme with lichens growing amongst the grass sward. A community of sheep’s fescue and meadow oat grass forms a rich mixture of grasses and broadleaved herbs while a grassland dominated by the coarse grass upright brome supports fewer herbs and is typical of undergrazed chalk downlands. From the history of land use in the area, these grasslands range from 40 to over 200 years old and present a unique opportunity for researching grassland habitat continuity.
Several rare species of southern chalkland wildflowers can be found – early gentian, chalk milkwort, bastard toadflax and field fleawort. The striking blue meadow clary might be spotted.This plant has a ‘near threatened’ classification and is found at only 21 locations in the country.
In addition to grassland, 20% of southern England’s Juniper scrub is also found at Porton Down.Beech, sycamore and Scots pine trees have been widely planted and semi-natural woodland of oak, ash and yew can also be found.Yellow birds-nest and bird’s nest orchid which obtain nutrients from decaying plant material are some of the less common woodland plants that can be found.The white helleborine, a species which is associated with beech woodland is also present.