Report 365
Characterisation of Hydrological Protection Zones at the Margins of Designated Lowland Raised Peat Bog Sites
(2005)
Morgan-Jones, W. Poole, J.S, Goodall, R
Peat bogs are part of our natural heritage in the UK. Not only did they influence our pattern of settlement and agriculture, they also preserve a record of our past. In addition, they support a distinctive array of plants and animals, able to survive in conditions hostile to most others. They have their own dynamic, in that the peat grows and spreads according to the character of the landscape and the climate. Or rather, it did, until we discovered peat’s uses as fuel and in horticulture, and that peat bogs could be cultivated if drained.

Summary

 
Peat bogs are part of our natural heritage in the UK.  Not only did they influence our pattern of settlement and agriculture, they also preserve a record of our past.  In addition, they support a distinctive array of plants and animals, able to survive in conditions hostile to most others.  They have their own dynamic, in that the peat grows and spreads according to the character of the landscape and the climate.  Or rather, it did, until we discovered peat's uses as fuel and in horticulture, and that peat bogs could be cultivated if drained.
 
The National Parks and Access to the Countryside Act of 1949 set out a systematic approach to our conservation of habitats and species, which has been developed in successive legislation.  So, amongst other habitats, we conserve lowland raised bogs through designations such as SSSI and SAC.  Our big challenge lies in not only perpetuating continued growth of what remains of our 'living' peat bogs, but also breathing new life into accumulations of peat that are now largely moribund and isolated from their original wetland environment.  The link with topography, climate and local hydrology has been broken.
 
Our first approach was to identify 'special interest', and draw a site boundary around it.  For bogs, the line usually followed the interface between what was still identifiable as peat bog, and agricultural land derived from where it used to be.  The appreciation that we also have to restore the hydrology of such a bog before it can resume growth is relatively recent.
 
There is a specific relationship between the level of water around a bog and that at its centre.  Take away the water from around its edge, and the centre suffers.  Important bog margin habitats such as lagg fen and wet woodland are also lost, creating artificially sharp boundaries between what remains of the bog and its hinterland.  The corollary is that if bog restoration is to be successful, we must return water to the edge of the bog.  This may not be as a sheet of open water, but rather, as waterlogged land supporting fen or other wetland.  The big dilemma for conservation managers, and those owning land around the bog, is how far and how much.  This is why we need a method to define Hydrological Protection Zones or HPZs.
 
The theory behind the method and how it translates into a standard approach is described in the report.  While it may remain an imprecise science, and dependent on how certain measurements are carried out or judgements made, it is a significant step forward from which we can produce refinements as our knowledge and experience grow.
 
Being able to identify such land has a number of uses.  Procedurally, it enables the designated site boundary to be drawn to include all land judged necessary to provide and maintain the hydrological functions needed to conserve the special features of the site.  In practical terms, it provides a more precise steer for the prioritisation of agri-environment scheme money in achieving favourable condition on the bog and identifies which agricultural land is likely to become wet when rewetting measures are used within the peat bog itself.  The writing of Water Level Management Plans by drainage authorities will also use it in determining which land should remain wet, and by how much.  Institutions and bodies that manage peat bogs will be able to include all relevant land within their management plans.
 
The UK Biodiversity Action Plan has a Habitat Action Plan for lowland raised bog.  Achieving favourable conservation status for the habitat will require us to manage designated and undesignated sites.  The method provides a basis on which to draw up plans for bog and other wetland conservation that could become part of Regional Spatial Strategies (in England) and habitat visions for particular areas where raised bog is an important and characteristic component.
 
The challenge now is to apply the method to all our remaining peat bog sites and to remove some of the uncertainty about the future of land lying around their edges.
 
 
 
Roger Meade
Chair of the JNCC's Lead Co-ordination Network for Lowland Wetlands
 
 
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Download in sections:

The maps are available for download in high resolution (300dpi) for printing and low resolution (150dpi) for screen viewing.  The high resolution files are very large and will take approximately 2.5mins per mb to download using a 56 kb modem connection.

Please Note that the case study sites show preliminary site boundary classifications, based on a limited number of sample points and therefore should be used for guidance only. The original print version and pdf of this report included references to Cors Goch. This was an error and the pdf version here has been amended and the corresponding map removed from Appendix B.

  • Download Annex B - Desk Study Description of the Conditions at the Margins of 15 Lowland Raised Bog Sites.
      High Low
    Boundary classification for Fenns, Whixall, Bettisfield, Wem and Cadney Mosses (England) derived from desk study description 6.4 mb 564 kb
    Boundary classification for Holcroft Moss (England) derived from desk study description 2.7 mb 707 kb
    Boundary classification for Thorne Moors (England) derived from desk study description 2.3 mb 567 kb
    Boundary classification for Wedholme Flow (England) derived from desk study description
    2.9 mb 665 kb
    Boundary classification for Winmarleigh Moss (England) derived from desk study description 2.7 mb 684 kb
    Boundary classification for Ballynahone Bog (Northern Ireland) derived from desk study description 3.6 mb 910 kb
    Boundary classification for Cranny Bog (Northern Ireland) derived from desk study description 2.9 mb 249 kb
    Boundary classification for Dunloy Bog (Northern Ireland) derived from desk study description 3.9 mb 1 mb
    Boundary classification for Garry Bog (Northern Ireland) derived from desk study description 3.2 mb 868 kb
    Boundary classification for Tattenmona Bog (Northern Ireland) derived from desk study description 2.3 mb 639 kb
    Boundary classification for Blawhorn Moss (Scotland) derived from desk study description 2.5 mb 620 kb
    Boundary classification for Braehead Moss (Scotland) derived from desk study description 1.7 mb 443 kb
    Boundary classification for Flanders Moss (Scotland) derived from desk study description 2.5 mb 617 kb
    Boundary classification for Longbridge Muir (Scotland) derived from desk study description 3.5 mb 567 kb
    Boundary classification for Cors Caron (Wales) derived from desk study description 2.2 mb 528 kb


Please Note that the case study sites show preliminary site boundary classifications and preliminary HPZ width calculations and should therefore be used for guidance only. The HPZ width calculations shown here are based on an earlier iteration of the method that made greater use of the equation including a seepage element. Following the production of these case study examples and as a result of further fieldwork and testing, the number of situations in which this modified equation was considered appropriate was revised. The final HPZ widths produced by following the guidance in this report would not therefore necessarily equate directly with those given in the following examples. In addition, with the exception of Fenns, Whixall, Bettisfield, Wem and Cadney Mosses, the fieldwork was limited in scope and only a relatively small number of sample points were used to construct the HPZ.


 

  • Download Annex C - Field Checking of the Conditions at the Margins of 6 Lowland Raised Bog Sites
      High Low
    Boundary classification for Thorne Moors (England) following field work.
    2.3 mb 188 kb
    Boundary classification for Wedholme Flow (England) following field work. 2.9 mb 667 kb
    Boundary classification for Blawhorn Moss (Scotland) following field work. 2.5 mb 613 kb
    Boundary classification for Garry Bog (Northern Ireland) following field work. 3.3 mb 850 kb
    Boundary classification for Cors Caron (Wales) following field work. 2.2 mb 550 kb
    Boundary classification for Fenns, Whixall, Bettisfield, Wem and Cadney Mosses (England) following field work.
    6.5 mb 582 kb

  • Download Annex D - Preliminary Hydrological Protection Zone Width Calculations for 6 Lowland Raised Bog Sites
      High Low
    Preliminary Hydrological Protection Zone (HPZ) width calculation for Thorne Moors (England).
    2.5 mb 591 kb
    Preliminary Hydrological Protection Zone (HPZ) width calculation for Wedholme Flow (Scotland). 2.9 mb 683 kb
    Preliminary Hydrological Protection Zone (HPZ) width calculation for Blawhorn Moss (Scotland). 2.6 mb 631 kb
    Preliminary Hydrological Protection Zone (HPZ) width calculation for Garry Bog (Northern Ireland). 3.3 mb 860 kb
    Preliminary Hydrological Protection Zone (HPZ) width calculation for Cors Caron (Wales)
    2.2 mb 546 kb
    Preliminary Hydrological Protection Zone (HPZ) width calculation for Fenns, Whixall, Bettisfield, Wem and Cadney Mosses (England). 6.4 mb 582 kb
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ISSN 0963-8091
 
Please cite as: Morgan-Jones, W. Poole, J.S, Goodall, R, (2005), Characterisation of Hydrological Protection Zones at the Margins of Designated Lowland Raised Peat Bog Sites, JNCC Report 365, ISSN 0963-8091