Crymlyn Bog/ Cors Crymlyn

General site character

• Inland water bodies (Standing water, Running water) (1.6%)
  
• Bogs, Marshes, Water fringed vegetation, Fens (86%)
  
• Heath, Scrub, Maquis and Garrigue, Phygrana (0.6%)
  
• Humid grassland, Mesophile grassland (3.5%)
  
• Broad-leaved deciduous woodland (8.3%)
  

Annex I habitats that are a primary reason for selection of this site

• 7140 Transition mires and quaking bogs

  Transition mires and quaking bogs occur on deep, wet topogenous peats over a relatively small area of this extensive coastal lowland site. Bottle sedge Carex rostrata and bogbean Menyanthes trifoliata are important components of some stands, together with common cottongrass Eriophorum angustifolium, water horsetail Equisetum fluviatile, star sedge Carex echinata, the locally rare mud sedge Carex limosa and, in places, the nationally rare slender cottongrass Eriophorum gracile. The floristic character of some of these stands displays affinities to NVC types M9 Carex rostrata – Calliergon cuspidatum/giganteum mire and S27 Carex rostrata – Potentilla palustris tall-herb fen, but other expressions of this habitat at Crymlyn include a stronger poor-fen element in which bog-mosses (including Sphagnum squarrosum, S. denticulatum and S. fimbriatum) figure prominently. The transition mire and quaking bog at this site is vulnerable to the continuing expansion of common reed Phragmites australis, encouraged by trends of increasing site wetness, nutrient-enrichment and lack of grazing.

• 7210 Calcareous fens with Cladium mariscus and species of the Caricion davallianae  * Priority feature

  Crymlyn supports the largest area of Cladium-dominated vegetation in south Wales. Many of the stands in which great fen-sedge Cladium mariscus occurs as sole dominant are typically species-poor, but other areas display a more diverse vegetation in which tufted-sedge Carex elata, royal fern Osmunda regalis and a range of tall-herb fen species are prominent. Some of these stands are unique in a Welsh context and are strongly reminiscent of NVC type S24 Phragmites australis – Peucedanum palustre tall-herb fen, which is otherwise largely confined to eastern England.

Annex I habitats present as a qualifying feature, but not a primary reason for selection of this site

• 91E0 Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae)  * Priority feature

Annex II species that are a primary reason for selection of this site

• Not Applicable

Annex II species present as a qualifying feature, but not a primary reason for site selection

• Not Applicable