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
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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Printed to order
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