Lower Bostraze and Leswidden SSSI
Encyclopedia
Lower Bostraze And Leswidden SSSI is a biological Site of Special Scientific Interest, located on the Penwith Peninsula, Cornwall
, a little to the east of St Just
, approximately 8 km west of Penzance
.
There are two discrete parts of this site - Lower Bostraze China Clay Works and Leswidden Block Works; together they are 23,000 m² in size. Lower Bostraze is located at , and Leswidden at .
The site was notified as an SSSI in 1996. The site lies within the Cornwall Area of Outstanding Natural Beauty and the Penwith Heritage Coast and is partly within the West Penwith Environmentally Sensitive Area.
, part of the Cornubian batholith
. Zones within the granite, altered by kaolinisation, have been extensively worked for china clay until recent years. Both areas are located within disused china clay workings, consisting of pits, benches, spoil tips and granitic debris with sparse vegetation cover.
Marsupella profunda. This species is rare in a British context (it is known from only one other location in
Britain, also in west Cornwall). However it is also internationally rare, being known only from Portugal
, the Canary Islands
, the Azores
and Madeira; throughout this range it is a rare species.
At Lower Bostraze and Leswidden, Western Rustwort is generally found growing on micaceous or clay waste substrates which are flat or gently sloping. Some patches occur on granitic rocks,usually where these are soft or crumbling. It appears to be a pioneer species
, the largest populations being found on surfaces showing the early stages of colonisation
by other bryophyte
s and by vascular plant
s.
The conservation charity Plantlife
designated the St Just Moors, part of this SSSI, an Important Plant Area for the occurrence of Western Rustwort and the green algae
desmids.
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...
, a little to the east of St Just
St Just in Penwith
St Just is a town and civil parish in Cornwall, England, United Kingdom. The parish encompasses the town of St Just and the nearby settlements of Trewellard, Pendeen and Kelynack: it is bounded by the parishes of Morvah to the north-east, Sancreed and Madron to the east, St Buryan and Sennen to...
, approximately 8 km west of Penzance
Penzance
Penzance is a town, civil parish, and port in Cornwall, England, in the United Kingdom. It is the most westerly major town in Cornwall and is approximately 75 miles west of Plymouth and 300 miles west-southwest of London...
.
There are two discrete parts of this site - Lower Bostraze China Clay Works and Leswidden Block Works; together they are 23,000 m² in size. Lower Bostraze is located at , and Leswidden at .
The site was notified as an SSSI in 1996. The site lies within the Cornwall Area of Outstanding Natural Beauty and the Penwith Heritage Coast and is partly within the West Penwith Environmentally Sensitive Area.
Site Description
Both parts of the site are underlain by the Land's End graniteGranite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
, part of the Cornubian batholith
Cornubian batholith
The Cornubian batholith refers to the group of associated granite intrusions which underlie the south-western peninsula of Great Britain. The main exposed masses of the batholith are seen at Dartmoor, Bodmin Moor, St Austell, Carnmenellis, Land's End and the Isles of Scilly. It formed during the...
. Zones within the granite, altered by kaolinisation, have been extensively worked for china clay until recent years. Both areas are located within disused china clay workings, consisting of pits, benches, spoil tips and granitic debris with sparse vegetation cover.
Biological Interest
The site's SSSI status is due to the presence of important populations of a very rare liverwort, the Western RustwortWestern Rustwort
Marsupella profunda is a liverwort.The species is rare in a British context; it is known from just three locations, all in west Cornwall. Two of these sites are protected as the Lower Bostraze and Leswidden SSSI and the other as St Austell Clay Pits SSSI...
Marsupella profunda. This species is rare in a British context (it is known from only one other location in
Britain, also in west Cornwall). However it is also internationally rare, being known only from Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
, the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
, the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
and Madeira; throughout this range it is a rare species.
At Lower Bostraze and Leswidden, Western Rustwort is generally found growing on micaceous or clay waste substrates which are flat or gently sloping. Some patches occur on granitic rocks,usually where these are soft or crumbling. It appears to be a pioneer species
Pioneer species
Pioneer species are species which colonize previously uncolonized land, usually leading to ecological succession. They are the first organisms to start the chain of events leading to a livable biosphere or ecosystem...
, the largest populations being found on surfaces showing the early stages of colonisation
Colonisation (biology)
Colonisation is the process in biology by which a species spreads into new areas, regions, and continents. It is sometimes also referred to as immigration, but colonisation often refers to successful immigration with integration to a community, having resisted initial local extinction.One classic...
by other bryophyte
Bryophyte
Bryophyte is a traditional name used to refer to all embryophytes that do not have true vascular tissue and are therefore called 'non-vascular plants'. Some bryophytes do have specialized tissues for the transport of water; however since these do not contain lignin, they are not considered to be...
s and by vascular plant
Vascular plant
Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...
s.
The conservation charity Plantlife
Plantlife
Plantlife is a wild plant conservation charity. As of 2007, its membership was 10,500 and it owned 23 nature reserves around the UK.-History:It was founded in 1989 with its first President being Professor David Bellamy. By 1999 it had 22 nature reserves....
designated the St Just Moors, part of this SSSI, an Important Plant Area for the occurrence of Western Rustwort and the green algae
Green algae
The green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
desmids.