Blanket bogs are ombrotrophic or rain-fed peatlands that develop in oceanic regions where high precipitation & low summer temperatures result in an excess of soil moisture. Peat develops over large expanses of undulating ground, forming a ‘blanket’ over the ground of variable depths (JNCC)
- Site: High rainfall & low temperatures. Altitudes >200metres
- Soil: Water-logged & oxygen-limited
- Main species: Sphagnum moss, heather, cross-leaved heath, deergrass, bog cotton, sundews
- UK: <1.5 million ha
- NI: 140,000 ha
- Blanket bogs develop in upland areas at altitudes above 200 metres, where rainfall is high & temperatures are low. Although blanket bogs are restricted globally, they are a relatively extensive semi-natural habitat in the UK & Ireland (NIEA, 2003).
- Blanket bogs are located on flat to moderately sloped landscapes (Laine et al. 2006; NIEA, 2005) & peat depth varies but is typically in the range of 0-6 metres. The surface pattern consists of a mosaic of hummocks, hollows & lawns. Blanket bogs are not restricted to areas of poor drainage but can cover vast areas of land.
- Heavy rain washes minerals such as iron from the soil surface layers, where it is deposited in lower layers, forming an ‘iron pan’. Water cannot pass through this layer, causing the soil surface to become waterlogged. With excess water & oxygen shortage, peat accumulates & can cover extensive land areas.
- Blanket bogs are harsh environments due to soil acidity & deficiency of nutrients, but they support the growth of a range of plant species, many of which are similar to those identified in the NVC of Great Britain. Sphagnum mosses are characteristic of blanket bogs & are responsible for water retention.
- NVC Communities include M1 to M3, M17 Tufted Clubrush Scirpus cespitosus – Hare’s-tail Cottongrass Eriophorum vaginatum blanket mire, M18 cross-leaved heath Erica tetralix – Sphagnum papillosum raised & blanket mire & M19 Common Heather Calluna vulgaris – Eriophorum vaginatum. Others include deergrass, purple moor-grass, black bog-rush & the liverwort Pleurozia purpurea.
Current Status in UK & Northern Ireland
- Blanket bog is a limited habitat in a global context
- In the UK blanket bog covers just less than 1.5 million ha. The NIPS (1988) (Cruickshank & Tomlinson, 1988) estimated that 85% of peatland was blanket bog in Northern Ireland.
- Blanket bog vegetation covers an estimated 140,000 ha (Cruickshank & Tomlinson, 1988). Approximately 22,000 ha (15%) of this area is intact, 64,000 ha (46%) has been hand-cut for fuel & 14,000ha (10%) has been drained. The remaining 40,600 ha (29%) is too severely degraded that it cannot be restored (NIEA, 2005).
- The west of NI supports extensive areas of blanket bog as a result of the increased altitude & precipitation. In the east the Antrim Plateau has the largest area (peatlandsni, 2004).
- Afforestation is a principle cause of the reduction of blanket bog.
- Carn/Glenshane Pass
- Garron Plateau
Biological Importance & Priority Species
- Blanket bogs support a range of terrestrial & aquatic species.
- They are important breeding sites for bird species such as the skylark & red grouse . They support the golden plover (SoCC) & red-throated diver (SoCC). Blanket bogs are fundamental feeding sites for buzzards & peregrine falcons (McLaughlin, 2007). Further bird species supported include the merlin , Greenland white fronted goose & meadow pipit .
- The common lizard Lacerta vivipara, protected under Schedule 5 & 7 of the Wildlife Order, may be seen on upland blanket bogs. Red deer may also be temporarily found (peatlandsni, 2004).
- Invertebrates include the Green Hairstreak butterfly (SoCC).