Arable Land

Arable land is an open, dynamic, man-made habitat which supports a special flora of vascular plants and bryophytes, which includes several species that are rarely encountered elsewhere. Most of these fall into the category of agricultural weeds and many have shown declines in their abundance and distribution in the British flora in the last 100 years as a result of agricultural improvements, changing farming practices and the use of selective herbicides (weed killers). A significant proportion of arable weeds are achaeophytes, non-native species that have been part of our flora for more than 400 years and usually for much longer than that, sometimes with origins that coincide with ancient historic or even pre-historic farming cultures. Good examples are Charlock (Sinapis arvensis), poppies (Papaver spp.), Black Bindweed (Fallopia convolvulus), Shepherd's-needle (Scandix pecten-veneris), Common Fumitory (Fumaria officinalis), Corn Marigold (Glebionis segetum) and Corncockle (Agrostemma githago). But there is also a suite of common native weeds that are someimes abundant and characterise this habitat such as Chickweed (Stellaria media), Common Ramping-fumitory (Fumaria muralis), Fat Hen (Chenopodium album), Scentless Mayweed (Tripleurospermum inodurum), Sun Spurge (Euphorbia helioscopa), Groundsel (Senecio vulgaris), Shepherds Purse (Capsella bursa-pastoris), Field Penny-cress (Thlaspi arvense), Scarlet Pimpernel (Lysimachia arvensis), Common Couch-grass (Elytrigia repens), dead nettles (Lamium hybridum and Lamium purpureum) and knotweeds (Persicaria lapathifolium and Persicaria maculosa). Others, which are not as common anymore, include Field Pansy (Viola arvensis). Corn Spurry (Spergula arvensis), Black Mustard (Brassica nigra) and the fluellens (Kiickxia elatine and Kickxia spuria). Also well represented are some of our most widespread neophytes (i.e. species that have been introduced into the British flora since AD 1600), particularly species such as Common Field-speedwell (Veronica persica), Pineappleweed (Matricaria discoidea) and Lesser Swinecress (Lepidium disymum).

Arable land is also characterised by a diverse collection of bryophytes which includes common species of open, disturbed ground such as Barbula unguiculata, Bryum dichotomum, various tuberous bryums (e.g. Bryum rubens), Funaria hygrometrica, and Marchantia polymorpha ssp. ruderalis but also species that are more specific to this habitat such as hornworts, (e.g Phaeoceros spp.), crystalworts (e.g. Riccia glauca, Riccia sorocarpa and less commonly Riccia subbifurca), frillworts (e.g. Fossombronia pusilla and Fossombronia wondraczekii), Acaulon muticum, Entoshodon fascicularis, Ephemerum minutissimum, Phascum cuspidatum, Physcomitrium fascicularis and Weissia longifolia.

The ecology of arable habitats is largely determined by a management that involves sytematic and regular disturbance (e.g. ploughing) and also the use of fertilisers which ensures a high nutrient content, particularly in nitrogen and phosphorus. But specific ecological variations and species composition are influenced by other factors too such as soil charcateristics, e.g. clay content, drainage and base-richness, and also their history and past use, e.g. whether they are being used primarily for root vegetables, brassicas or cereals and the extent to which stubble is managed.

Most of the arable land in West Glamorgan is distributed in the coastal lowlands, with the highest concentraion in Gower. Many Gower fields have been cultivated for arable crops for hundreds of years and the Veil (also called the Vile) in Rhossili has a very long history that dates back at least to the early Middle Ages. Quentin Kay's report to the National Trust (The arable weed flora of the veil, a medievil open field system at Rhossili in the western Gower Peninsula) provides an excellent overview of the history and ecology of this site. There is very liitle arable land on the South Wales Coalfield but there are some large fields in the south-eastern parts of West Glamorgan between Margam and the Kenfig River.