Gweunydd Glan-y-glasnant


Gweunydd Glan-y-glasnant is a Site of Special Scientific Interest in Carmarthenshire, Wales, designated in 1993 for its botanical features.

SSSI

Gweunydd Glan-y-glasnant SSSI is a set of unimproved cattle-grazed pasture and hay meadows, extending to, on varying thicknesses of glacial till overlaying coal measures and shaley sandstone. It is situated at above sea level in the upper valley of the Nant Glas, a tributary of the River Gwili, south-west of Cross Hands and east of Tumble.
The site is designated as an SSSI for its species-rich neutral grassland, rare now in Great Britain with 97% of such land lost through agricultural improvements since 1930. Such fields provide habitat for up to 30 distinct species of plant per square metre, in contrast with the 1 or 2 species per square metre on improved grassland fields. The site varies from pH neutral mesotrophic soil to damper acidic grassland.
Species common on the neutral grasslands include common bent, sweet vernal-grass, clovers, common knapweed and bird's-foot-trefoil. There are smaller communities of tormentil, meadow vetchling, yarrow, self-heal, as well as common spotted-orchid and the adder's-tongue fern. A distinct part of the site is a fen-meadow hosting purple moor-grass and meadow
thistle.
A range of other habitats on the site, including acid grassland, scrub, semi-natural broadleaved woodland, hedgerows, individual trees, earthbank field boundaries, streams, ditches and rock outcrops support a broad range of fauna.