Calaminarian grassland is grassland where the process of seral succession has been halted due to the toxicity of soils containing high levels of toxic metal ions. These habitats may be semi-natural on naturally exposed deposits, or the result of mining, or from erosion by rivers, sometimes including washed-out mine workings. In the United Kingdom calaminarian grassland is regarded as one of its 'habitats of principal importance for biodiversity conservation' and is predominantly found on industrial or post-industrial land, especially in the east of Cumbria and western dales, the Peak District and north west Wales and parts of the Scottish Highlands. Semi-natural examples are rarer and found mainly in the Highlands and Islands of Scotland. Some examples include

Cwmystwyth Cwmystwyth (also Cwm Ystwyth, ; en, "valley of the River Ystwyth") is a village in Ceredigion, Wales near Devil's Bridge, and Pont-rhyd-y-groes. The Ordnance Survey calculates Cwmystwyth to be the centre point of Wales (; ). History Dis ...

in West Wales,

Halkyn Mountain Halkyn ( cy, Helygain ; Flintshire Welsh: ''Lygian '') is a village and community in Flintshire, north-east Wales and situated between Pentre Halkyn, Northop and Rhosesmor. At the 2001 Census the population of the community was 2,876, increasi ...

in Flintshire,

Upper Teesdale Upper Teesdale is a Site of Special Scientific Interest (SSSI) in the west County Durham, England. It encompasses an extensive upland area that includes the headwaters of the River Tees and the surrounding catchment area upstream of the village ...

in County Durham, Oxclose in Tyne and Wear,

Caenlochan Caenlochan ( gd, Cadha an Lochain) is a glen in the Grampian Mountains of Scotland. Under EU Natura 2000 legislation it is a Special Area of Conservation for botanical reasons, containing plant communities found nowhere else in the UK. It is also ...

in eastern Scotland, the Isle of Rhum in western Scotland and

Keen of Hamar Keen of Hamar is a nature reserve on Unst, in Shetland, Scotland, managed by Scottish Natural Heritage. The reserve is primarily of botanical interest, for example for populations of '' Cerastium nigrescens'', a plant unique to Unst. Keen of Ha ...

in Shetland. Situations where such grasslands occur include near-natural, on

Serpentine soil Serpentine soil is an uncommon soil type produced by weathered ultramafic rock such as peridotite and its metamorphic derivatives such as serpentinite. More precisely, serpentine soil contains minerals of the serpentine subgroup, especially anti ...

and

mineral vein In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation. The hydraulic flow involved ...

outcrops with thin soils; on riverside shingle in areas with high levels of lead and zinc, especially when there has been mining activity upstream; spoil heaps and areas surrounding old mine workings, especially in limestone areas. Species typical of Calaminarian grasslands include spring sandwort (''

Minuartia verna ''Minuartia verna'' is a scarce species of flowering plant in the family Caryophyllaceae, known by the common names spring sandwort and leadwort. It is a small mat-forming, perennial herb. Some authorities consider it a synonym of '' Sabulina ver ...

''), field pennycress (''

Thlaspi arvense ''Thlaspi arvense'', known by the common name field pennycress, is a flowering plant in the cabbage family Brassicaceae. It is native to Eurasia, and is a common weed throughout much of North America and its home. Description ''Thlaspi arvense' ...

''), genetically adapted races of species such as thrift ('' Armeria maritima'') and bladder campion (''

Silene uniflora ''Silene uniflora'' is a species of flowering plant in the family Caryophyllaceae known by the common name sea campion. Description ''Silene uniflora'' is a herbaceous perennial plant, similar in appearance to the bladder campion ('' Silene vulg ...

''). Other notable species include Young's helleborine (''

Epipactis youngiana ''Epipactis helleborine'' var. ''youngiana'', known as Young's helleborine, is a variety of orchid that is endemic to Great Britain. It has also been treated as a separate species, ''Epipactis youngiana''. Taxonomy ''Epipactis helleborine'' va ...

''), forked spleenwort ('' Asplenium septentrionale''), Cornish path-moss (''

Ditrichum cornubicum ''Ditrichum cornubicum'', commonly known as the Cornish path-moss, is a moss endemic to Cornwall, United Kingdom. First discovered in 1963, on a roadside west of Lanner, Cornwall by Jean Paton, it has since been found in two other places within ...

''), western rustwort (''

Marsupella profunda ''Marsupella profunda'', the western rustwort, is a liverwort native to Europe and known only from Portugal (Mainland, Azores and Madeira) and Great Britain (Cornwall) and has been sighted in the Canary Islands. It is a small reddish liverwort a ...

''), ''

Cephaloziella nicholsonii ''Cephaloziella'' is a genus of liverworts. ''Cephaloziella varians'' (Gottsche) Steph. is the only liverwort that occurs in the continental Antarctic. Species * '' Cephaloziella acanthophora'' * '' Cephaloziella aenigmatica'' * '' Cephalozi ...

'', '' Ditrichum plumbicola'', Scottish sandwort (''

Arenaria norvegica ''Arenaria norvegica'', also known as Arctic, English or Norwegian sandwort, is a low growing plant in the family Caryophyllaceae, found in northwest Europe. The diploid chromosome number is 2n=80. There are two recognised subspecies.

'') and Shetland mouse-ear (''

Cerastium nigrescens ''Cerastium nigrescens'', commonly known as the Shetland mouse-ear, Shetland mouse-eared chickweed or Edmondston's chickweed, is an endemic flowering plant found in Shetland, Scotland. It was first recorded in 1837 by botanist Thomas Edmonds ...

''). Grasslands of this type and the rocky outcrops they are associated with provide habitat for several of Britain's rarest plants. These include northern rock-cress (''

Arabis petraea ''Arabis'' ,''Sunset Western Garden Book,'' 1995:606–607 or rockcress, is a genus of flowering plants, within the family Brassicaceae. Description The species are herbaceous, annual or perennial plants, growing to 10–80 cm tall, usua ...

''), forked spleenwort ('' Asplenium septentrionale'') and Young’s helleborine (''

''). There are also a number of rare mosses, liverworts and lichens.

References

{{reflist Conservation in the United Kingdom

See also

References