Blanket bogs are areas in the uplands which have developed a mantle of peat more than 50 cm deep. They are found in areas of high rainfall with a cool humid climate. The vegetation of blanket bogs is usually characterised by the presence of bog mosses Sphagnum spp. together with species such as cotton-grass, heather and cross-leaved heath Erica tetralix, although on some sites this has been altered by inappropriate management. They usually occur in a mosaic with other habitats such as upland heathland, acid grassland and flushes. Blanket bogs are fed entirely by precipitation (ie, rain, snow etc). This differentiates them from fens, which receive inputs from groundwater.
Bogs in which peat is still accumulating through the growth and impeded decay of Sphagnum and Eriophorum are described as active. However, many bogs have been degraded through drainage and inappropriate management and are no longer forming peat. Both types of bog are included within the UK Biodiversity Action Plan.
The UK holds a significant proportion of the world’s blanket bog and so has a particular responsibility for its conservation. It is a habitat that has formed over thousands of years and which cannot be replaced. It supports a number of specialist plant species that are adapted to wet acidic conditions. These include bog rosemary, sundew, and bog asphodel Narthecium ossifragum.
Blanket bogs are important areas for breeding birds and support populations of national and international significance, many of which are listed on the RSPB’s national red list for birds. Species found include golden plover, merlin, red grouse, black grouse and dunlin. A variety of invertebrates are also found on this habitat including the large heath butterfly. The blanket bogs of the Region are of national significance for this species, with over 70% of the known sites in England and Wales for large heath occurring in Northumberland.
There are estimated to be just under 1.5 million ha of blanket bog in the UK, of which the majority is found in Scotland. England supports some 215 000 ha. This resource is decreasing in both quantity and quality. Figures suggest that there was a 21% reduction in the extent of blanket bog between the 1940s and the 1980s, largely due to afforestation.
The North East is noted for the quantity and quality of its peatlands. There is approximately 39 229.6 ha of blanket bog in the Region, which represents about 2.6% of the UK resource. Much of this is concentrated in the North Pennine moors and within the Northumberland National Park and is designated as SSSI. Many sites are regarded as being of international importance for their peatland habitats and/or bird populations and have received appropriate designations such as SACs, Ramsar sites and/or SPAs.
- Heavy grazing, especially when accompanied by other damaging practices, can damage vegetation. This is particularly a concern on some common land.
- Burning is damaging to blanket bogs and if carried out excessively can lead to the loss of Sphagnum species and other plants of interest.
- Extensive tracts of blanket bog have been drained in the past in an attempt to improve the quality of grazing. New drains continue to be dug and old drains cleaned in some areas. Even without maintenance most drains continue to lower the adjacent water table and may initiate erosion.
- Some bogs are losing areas of peat because of erosion.
- Blanket bogs are sensitive to recreational and military use. The use of all-terrain vehicles for recreation, agricultural and sporting activities can also result in localised erosion.
- Developments of wind farms, communication masts etc are increasingly being proposed for areas of blanket bog and may lead directly to a loss of habitat, disruption of the local hydrology, or increased disturbance to nesting birds.
- Raptor populations are still subject to persecution.
- Afforestation has led to losses of blanket bog in the past. Forestry can also have indirect effects on bogs by altering their hydrology and increasing predation pressures on ground nesting birds. The seeding of conifers from adjacent plantations on to areas of bog is causing problems in some areas.
- Difficulties in negotiating agreements with commoners are hampering take-up of agri-environment schemes on common land.
- Climate change and global warming are a potential threat to this habitat.
Opportunities for protection and enhancement
- Payments for sympathetic grazing regimes, and blocking of drainage channels, on areas of blanket bogs are available under the Environmental Stewardship Scheme.
- The EU funded LIFE Project on the Border Mires has carried out restoration work, such as the blocking of drainage channels and the removal of self-seeded conifers.
- Forest Enterprise is restructuring its conifer plantations so that the forest edge can be withdrawn from sensitive mire areas.
- The North Pennines AONB's Peatscapes Project is currently blocking moorland drains to aid the restoration of upland blanket bogs.