Purple moor-grass & rush pasture is a characteristic habitat of the South Wales coalfield, where they are referred to locally as ‘rhos pastures’. The category encompasses a very wide range of vegetation types, all of which have nature
conservation value. Rhos pastures have been extensively reclaimed for agriculture, lost to development or allowed to deteriorate through lack of management in recent decades, however, and there are now estimated to be only approximatel about 35,000ha of this formerly widespread and common habitat remaining in the whole of Wales, about 160ha of which occur in Blaenau Gwent county borough.

This habitat type can support a diverse and characteristic invertebrate fauna, which may include the rare and protected marsh fritillary butterfly (Eurodryas aurinia) as well as a
number of geographically restricted plant species such as whorled caraway (Carum verticillatum), wavy St John’s-wort (Hypericum undulatum) and petty whin (Genista
anglica). However, none of these species has been recorded to date from the site. Only a very small area of this habitat was present within the site, and this was species-poor and degraded.

The dry acid grasslands within the site are in a degraded condition, having been afforested. The U1 acid grassland community which is recorded on the site is a rare community on natural substrates in Wales, although is relatively frequent on secondary substrates such as colliery shale. The acid grasslands support three plants which are considered to be local in the region, and eleven species considered indicative of speciesrich acid grasslands in the Guidelines for the Selection of Wildlife Sites in South Wales
(SWWSP 2004).

The heathland within the site is classed as upland heathland, being above the 250m contour line. There is an estimated 79,000ha of this habitat extant in Wales, 1400ha of which occur within the Blaenau Gwent county borough (CCW 2003). This habitat type is, however, relatively scarce within the rest of Europe and has its stronghold in the UK. This habitat type often supports notable bird species including species such as hen harrier, red grouse and black grouse, although none of these species have been recorded to date at Sirhowy Hill.

The heathland habitats of the site are in a degraded condition, having been afforested throughout the site, and are now suffering from succession. The heathland habitats support seven plant species which are considered local in the region, and sixteen species considered indicative of species-rich heathlands and acid grassland mosaics in the Guidelines for the Selection of Wildlife Sites in South Wales (SWWSP 2004).

Ponds are identified as a key habitat for conservation in the Blaenau Gwent LBAP, and certain specific types of ponds are also recognised as being of significance at the county, Welsh or UK level. Pond habitats may support rich assemblages of flora and fauna, including many rare plants and invertebrates as well protected fauna species such as great crested newt.

The site contains one large permanent pond (Cardiff Pond) and two smaller ponds, all of which are considered potentially suitable for great crested newt although this species has not been recorded on the site to date. Upland ponds elsewhere within the county borough have been found to support rich dragonfly assemblages which include scarce blue-tailed damselfly (Ischnura pumilio), black darter (Sympetrum danae) and keeled skimmer (Orthetrum coerulescens). Only one dragonfly species, common hawker (Aeshna juncea) was recorded from the site by the present survey, but it is likely that a range of others are also present. No rare or declining plant or invertebrate species have been recorded to date.