Blanket bogs need a cool and wet environment, with the total number of rain days being as important as total rainfall. Goode and Ratcliffe (1977) quote a minimum rainfall of 1 mm per day over 160 days per year for blanket bog development. Blanket bog peat accumulates in response to the slow decomposition of plants such as Sphagnum moss, under water logged conditions. The depth of the peat layer differs widely from site to site and indeed between different areas of the same site, but is typically between 2 and 4 metres in depth. It may be deeper in areas with underlying depressions and shallower near rocky outcrops and in the wettest areas, peat can form on slopes of up to 30°.

It is not known exactly when blanket bogs started to form. Some studies indicate that most blanket peat development began 5000-6000 years ago, but the range extends from 9000 - 1500 years ago. Tree stumps are frequently found in the lower levels of blanket bogs, indicating that they began to form following the clearance of forest cover by neolithic man. The relative significance of this activity in the formation of blanket bogs has yet to be determined.

Because blanket bogs extend over large areas, surface vegetation is cut off from the underlying soil or bedrock. This means that the only source of nutrients for these systems come from rainwater. Peat and old Sphagnum moss bind cations, hydrogen being the most predominant. Blanket bogs have a surface pH of around 3.8 - 4.0, making them somewhat hostile environments, being both acidic and nutrient poor.

The estimated 2,352,000 hectares of blanket bog in the UK supports a wide variety of both terrestrial and aquatic species. They may store important archaeological and palaeoecological material and are also thought to store a significant amount of carbon, an important factor when considering their conservation value. Some blanket bog sites are designated as common land and therefore have associated grazing and peat cutting rights. However, many blanket bog sites are protected as SSSIs (UK) or ASSIs (Northern Ireland). 50 of these sites are now designated as Special Areas for Conservation (SACs). In addition, some have been proposed as, or are already, Ramsar sites and some as Special Protection Areas (SPAs) under the EC Birds Directive.

In the last century, there has been a loss of blanket bog habitat due to:

• Afforestation of large areas
• Erosion
• Over grazing
• Burning
• Drainage
• Peat cutting and
• Atmospheric pollution.

Being a BAP Priority Habitat, there are measures in place to ensure the maintenance and improvement of sites. One of the targets is to maintain the present extent and overall distribution of blanket bog currently in favourable condition, and improve the condition of degraded sites so that the total area in favourable condition by 2005 is 340,000 hectares. Management regimes will be introduced to improve 280,000 hectares of degraded blanket bog back to favourable condition by 2010 and to improve the condition of a further 225,000 hectares of degraded blanket bog by 2015. These objectives and targets will be met by carrying out a number of actions, including:

• When reviewing management prescriptions in agri-environment schemes and woodland initiatives, consider whether additional measures are needed to maintain and/or improve the condition of blanket bog.
• Review and modify muirburn legislation to ensure appropriate management of blanket bog.
• Review and consider common land legislation with a view to improving the sympathetic management of upland commons.
• Review and amend Policy Planning Guidance in Wales, Scotland and Northern Ireland to enable consistent guidance to be issued to local authorities across the UK.
• Review and clarify distinction in planning law between ‘domestic’ and ‘commercial’ peat cutting operations and determine appropriate level of activity for which planning permission is required
• Appropriate selection and designation of SAC sites, to provide a higher level of protection to important areas.
• Designation of SACs occured in 2004 in Wales and 2005 in the rest of the UK. Selection and designation of Special Protection Areas (SPAs) under the EC Birds Directive is ongoing
• Contribute to the implementation of relevant action plans for rare and declining species associated with blanket mire in conjunction with the appropriate species steering groups
• Through various local initiatives, develop and promote training in the conservation, management and restoration of blanket mire, targeting this at representatives from all key agencies and at appropriate land managers
• Encourage and promote advice on the use of alternatives to peat, particularly as a fuel
• Establish a national inventory of blanket mire habitats by 2007, using agreed methodologies and with agreed definitions for determining the extent and condition of the habitat
• Commission and undertake research to establish the impact on blanket mires of peat extraction for fuel and horticultural purposes