Guidelines for the Selection of Biological Heritage Sites
6. Section 1: Habitat Guidelines
6.5 BOG
Application (all bog guidelines)
Bogs receive their water and nutrients primarily from rainfall and not from groundwater sources (cf. swamp and fen). They include raised bog (or moss) and blanket bog as defined in JNCC (1994). Bogs will normally comprise semi-natural vegetation developed over peat more than 0.5m deep (cf. heathland).
Justification (all bog guidelines)
The bogs of north and west Britain are collectively of international nature conservation significance. However, most of Lancashires bogs have been either destroyed (in the lowlands) or else severely degraded. These guidelines aim to identify all remnants of a formerly widespread and highly characteristic vegetation type in the County which are still of nature conservation importance.
Bo1 Lowland bog (mossland) sites over 0.5 hectare in extent in Landscape Zone West(1)over peat more than 0.5 metre deep which support semi-natural vegetation.
Application
Although sites which have been afforested are generally excluded here, those with some tree cover but which retain elements of their characteristic bog plant or animal communities may be considered for inclusion.
Justification
About 98% of the lowland raised mosses of Lancashire have now been reclaimed for agriculture or otherwise lost (Lancashire County Council n.d.). The habitat is now so rare that all uncultivated remnants (whether they are cut over and regenerated or not) larger than 0.5 hectare are considered to be of importance, and a key part of the Countys critical environmental capital (see Introduction, para. 2.1).
Bo2 Bog sites over 0.5 hectare with at least 25% of Sphagnum (bog-moss) cover.
Application
This guideline may be applied either to relict areas of Sphagnum cover, or to areas of regenerating Sphagnum cover.
Justification
Bogs with a high percentage of Sphagnum cover indicate either relatively little disturbance in the past or a regenerating bog-moss surface following the onset of more favourable local environmental conditions.
Sphagnum mosses are lost from bogs subjected to systematic drainage and/or burning. They provide the building material and habitat matrix for `classical raised and blanket bogs which support a number of rare and decreasing species (including rare species of Sphagnum itself).
Bo3 Bog over 0.5 hectare containing 3 or more species in Table 3.
Application
Species listed need only be present, irrespective of their abundance or distribution on the site concerned.
Justification
Few, if any, of the listed species will occur in those bogs which have been severely degraded by drainage, burning and heavy grazing. They are valuable indicators of more natural conditions which are now rare in Lancashires bogs.
| Scientific Name | Common Name |
| Andromeda polifolia | Bog Rosemary |
| Drosera rotundifolia | Round-leaved Sundew |
| Erica tetralix | Cross-leaved Heath |
| Myrica gale | Bog Myrtle |
| Narthecium ossifragum | Bog Asphodel |
| Trichophorum cespitosum | Deergrass |
| Vaccinium oxycoccus | Cranberry |
Bo4 Areas greater than 10 hectare in which
any of the following dwarf shrubs, either individually or in combination have
more than 25% average cover:
Calluna vulgaris
Heather
Vaccinium myrtillus
Bilberry
Empetrum nigrum
Crowberry
Application
This guideline should be applied to uncut or cut-over bogs provided that peat survives to a depth of at least 0.5m. However, some areas dominated by dwarf shrubs are, in fact, mosaics of bog and heathland (see Guideline He1) and cannot be readily differentiated. Where such areas otherwise comply with the terms of Guidelines Bo4 or He1 they may be selected under whichever is the most appropriate guideline.
Justification
Although much modified by human activities, larger areas of dry bog in which dwarf shrubs are a major component are likely to be of higher nature conservation value than those in which dwarf shrubs are rare or absent.
Bo5 The best examples of each of the following topographical or hydrological types of blanket bog remaining in each of the Landscape Zones(1) in which they occur, should these fail to meet other Bog guidelines.
Watershed mire
Spur mire
Valleyside mire
Saddle mire
Application
The best examples are selected on the basis of established general NCR criteria, and more particularly on the detailed guidance given for each of the listed topographical/hydrological types in NCC 1989 (pp166-170). Some mire systems are, in fact, mosaics of bog, and swamp and fen habitat (see Guideline Fe3), or are intermediate in character. Such sites may be considered for inclusion under Guidelines Bo5 or Fe3, whichever is the more appropriate.
Justification
In view of the drained and degraded state of much of the Countys blanket bog, it is considered important that the best remaining examples of the principal types of bog formation should be identified, even if these fail to meet the other guidelines in this section.
(1) See Appendix 1.
(2) Scientific and common names are taken from Stace
2nd Ed. (1997)