Jncc coastal Directories Project Region 11 The Western Approaches

3.5  Wet grassland
55
Table 3.5.1  
Wet grassland sites identified in Region 11
No. (see
Location
Grid ref.
Conservation
Notes
Map 3.5.1
)
status
Cornwall south coast
1
Fal Estuary
SW835429
Adjacent to SSSI
Agriculturally improved pasture
Isles of Scilly
2
Big Pool
SV879087
SSSI
Pool and wet maritime grassland
3
Lower Moors
SV912106
SSSI
10 ha maritime wet meadows and fen
Cornwall north coast
4
Kelsey Head
SW775600
SSSI
Brackish marsh
5
Amble Marshes
SW994746
SSSI
57 ha grazing marsh
Devon
6
Braunton Marshes
SS475345
Undesignated;
Grazing marsh
adjacent to two
SSSIs
Somerset
7
Porlock Marsh
SS880479
SSSI
Swamp and brackish ditch habitats
8
Bridgwater Bay
ST290480
SSSI
Grazing marsh with brackish and freshwater ditches
9
Southlake Moor
ST370300
SSSI
196 ha grazing marsh (part of Somerset Levels and Moors)
10
Curry and Hay Moors
ST323273
SSSI
472 ha grazing marsh (part of Somerset Levels and Moors)
11
Langmead Level
ST365335
SSSI
~ 84 ha grazing marsh (part of Somerset Levels and Moors)
12
Weston Level
ST353330
SSSI
~ 84 ha grazing marsh (part of Somerset Levels and Moors)
13
North Moor
ST325305
SSSI
676 ha grazing marsh (part of Somerset Levels and Moors)
14
Berrow Marsh
ST293520
SSSI
Avon
15
Puxton Moor
ST4263
SSSI
Part of Avon Levels.  Drainage ditch interest.
16
Biddle Street Triangle
ST4265
SSSI
Part of Avon Levels.  Drainage ditch interest.
17
Tickenham, Nailsea and
ST4369
SSSI
Part of Avon Levels.  Drainage ditch interest.
Kenn Moors
18
Gordano Levels
ST4573
NNR, SSSI
126 ha wet grassland
Gloucestershire
19
Upper Severn Estuary
SO720060
SSSI
Saltmarsh and pasture next to estuary
20
Walmore Common
SO740155
SSSI 
57 ha grassland with ditches, flooded in winter
21
Pennsylvania Fields
ST565953
SSSI
Grazing marsh/saltmarsh transition
Gwent
22
Magor and Undy
ST440860
SSSI
586 ha wet pasture (part of Gwent Levels)
23
Redwick and Llandevenny
ST410855
SSSI
940 ha wet pasture (part of Gwent Levels)
24
Whitson
ST390840
SSSI
938 ha wet pasture (part of Gwent Levels)
25
Nash and Goldcliff
ST350850
SSSI
954 ha wet pasture (part of Gwent Levels)
26
St. Brides
ST290825
SSSI
1,322 ha wet pasture (part of Gwent Levels)
27
Rhymney and Peterstone 
ST250800
SSSI
972 ha wet pasture (part of Gwent Levels)
South Glamorgan
28
Cog Moor
ST159694
Undesignated
Wet grassland
Source: Dargie et al. (1994).  Key: SSSI = Site of Special Scientific Interest; NNR = National Nature Reserve.  Note: areas have been rounded
to the nearest whole hectare.
solely for the biological interest of the ditches.  Designation
only extends 6 m from the edge of the ditches and does not
include the ploughed and reseeded fields.  In Wales plant
species such as narrow-leaved water-plantain Alisma
lanceolatum, frogbit Hydrocharis morsus-ranae, flowering-rush
Butomus umbellatus and whorl-grass Catabrosa aquatica are
chiefly restricted to the Gwent Levels.  
The importance of the region’s wet grasslands for birds
(see also 
sections 5.11
and 
5.12
) is indicated by the current
designation of the Somerset Levels and Moors as an SPA/
Ramsar Site, which although not coastal by the definition
used in 
Chapter 7
abuts areas of coastal wet grassland.  The
RSPB manage 526 ha of the Somerset Levels at Sedgemoor
as a reserve, notable for breeding waders, including the
nationally rare black-tailed godwit Limosa limosa, and also
quail Coturnix coturnix.  The reserve is also important for
passage and wintering birds, including whimbrel Numenius
phaeopus and Bewick’s swan Cygnus bewickii, both of which
are protected under Schedule 1 of the Wildlife &
Countryside Act.  Areas of wet grassland in the Wildfowl &
Wetlands Trust’s Slimbridge Reserve adjacent to the upper
Severn Estuary regularly hold internationally important
numbers of wintering Bewick’s swan Cygnus columbianus
bewickii and gadwall Anas strepera, as well as nationally
important populations of other duck and wader species.
Also adjacent to the Upper Severn is Walmore Common,
which supports internationally important numbers of
wintering Bewick’s swan and nationally important numbers
of several other wildfowl and wader species, notably
wigeon Anas penelope, gadwall, shoveler Anas clypeata and
pochard Aythya ferina. 
The Somerset and Gwent Levels are of national

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importance for the assemblage of invertebrate species they
support, including many rare and notable beetle, bug and
fly species (see also 
section 5.3
).  Drake et al. (1984)
identified a total of eighteen nationally rare Red Data Book
(RDB) and 124 nationally notable invertebrate species on the
Somerset Levels, and Drake (1986) found 21 RDB species
and 97 notable species on the Gwent Levels.  Although the
conservation status of some of these species has
subsequently been downgraded, the wealth of the
invertebrate fauna of both these areas is unquestionably of
national importance.  Important species found in both areas
include the great silver water beetle Hydrophilus piceus, the
diving beetle Hydaticus tranversalis and the soldier fly
Odontomyia ornata.
3.5.3  Human activities
The Braunton Marshes former SSSI next to the Taw-Torridge
Estuary was denotified in 1987 as a result of significant
reduction of its conservation interest.  Although this area is
identified as having considerable potential, its conservation
interest was thought to have been reduced by the change
from hay meadow management to all-year round grazing,
and possibly by pollution of the ditches.  Braunton Marshes
are currently considered as a high priority for water level
management.
The Somerset Levels and the Gwent Levels have been
subject to agriculture and management, including land
claim, since the Roman occupation and have a rich
archaeological heritage associated with man’s use of the
Severn Estuary and its marshes since prehistoric times (see
also 
Chapter 6
).  Much of the low-lying land now occupied
by wet grassland was claimed from the intertidal area or the
fringing freshwater marshes of the estuary.  The Levels have
suffered severe damage due to intensification of farming
and increased land drainage.  This has led to the conversion
of much floristically rich pasture to species-poor improved
pasture and arable land, which are also of much less value
for breeding wading birds.  Similarly, improved drainage
and the use of fertilisers have resulted in the ecological
impoverishment of many of the ditch systems as a result of
nutrient enrichment, reduced water flows and
unsympathetic ditch management.  An additional threat on
the Somerset Moors is the habitat destruction caused by
peat cutting.  Peat shrinkage due to excessive drainage and
consequent drying out and oxidation is a further source of
concern as it leads to irreparable damage to the soils and
thus changes in the habitats they support.  There is also
considerable concern about damage to archaeological
remains as a result of excess drying of the peat moors.
Mountford & Sheail (1984) concluded from the historical
record that “it is clear that many species have experienced a
decline rather than an increase”, which they attributed
largely to peat cutting and agricultural improvement.  They
also noted that the ditch communities of the Somerset
Levels have remained much less altered than those of the
Moors and pastures, a view supported by the results of the
Somerset Wetlands Project, an extensive survey of the flora
carried out by the Nature Conservancy Council in 1976-78.  
Water level management schemes are being developed for
wet grasslands throughout the region.  In response to concern
over the long-term future of the Somerset Levels, the Water
Level Management Steering Committee (WLMSC) was set up
in 1988, and the (then) National Rivers Authority (NRA - now
the Environment Agency) have since developed a water level
management and nature conservation strategy (NRA Wessex
Region 1992).  The WLMSC have set up trial areas for raising
water levels, the ecological effects of which are being
monitored by MAFF, English Nature and the Environment
Agency.  Further conservation management by SSSI
landowners is encouraged on the Somerset Levels in order to
maximise diversity.  This may include provision of pools for
foraging waders, manure fertilisation to increase invertebrate
density, and predator control and bank reprofiling.  The wet
grassland of the Gordano Levels NNR is managed through
controlled summer grazing, mostly by cattle.
The development pressures that have already resulted in
the loss of much wet grassland to the west of the Gwent
Levels and around Cardiff and Newport remain a threat.
The landfall, toll plaza and approach roads for the Second
Severn Crossing, commercial developments (including the
Europark development at Llandevenny), and an extension
to the landfill site at Lamby Way have all contributed to the
loss of wet grassland in the region.  There is also a proposal
for an M4 relief road that would affect the Gwent Levels.
Pressures from such developments are particularly strong in
south Wales, where development of these areas to create
employment is an economic priority.
3.5.4  Information sources used
The effects of changing agricultural practices on the
terrestrial flora of the Somerset Moors and Levels is
comparatively well documented (Mountford & Sheail 1984)
and can be assessed here much more accurately than for
many other regions of the UK.  Mountford & Sheail (1984)
also undertook extensive analysis of their survey results to
identify the effect that different factors such as ditch depth,
bank gradient, cattle trampling and shade had on the
aquatic flora.
Both the Somerset Levels and Gwent Levels are well
surveyed, compared with many other areas of wet grassland
in Britain.  Recently, surveys of the ditch flora have been
carried out on the Gwent Levels by Glading (1984),
Mountford & Sheail (1984) and Winder et al. (1991), and the
Countryside Council for Wales (CCW) hold Phase II survey
data for areas of the Gwent Levels and Cog Moor in South
Glamorgan.  Invertebrate fauna surveys were carried out by
the Nature Conservancy Council on the Somerset Levels
(Drake et al. 1984) and the Gwent Levels (McLean 1982;
Drake 1986), and these provide many data on the
conservation value of these habitats.  CCW hold a body of
information on the Gwent Levels as part of the Severn
Estuary Coastal Cell database, and considerable ecological
information has been collected to monitor the effects of the
construction of the Severn Crossing on the Caldicot Level
and the Avon Levels (Environmental Advisory Unit 1991;
SGS Environment 1995).  Surveys have also been carried out
as part of the Environmental Assessment of other proposed
schemes, including extension of the Lamby Way Landfill
(Environmental Advisory Unit 1993).
Much of the work on water level management schemes
in the region was pioneered by the RSPB and is discussed in
Burgess & Hirons (1990) with reference to work carried out
managing water levels on a number of sites, including West
Sedgemoor.
Region 11  Chapter 3  Terrestrial coastal habitats
56

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