Jncc coastal Directories Project Region 11 The Western Approaches

3.5.1  Introduction
Wet grassland includes both coastal grazing marsh subject
to maritime influence and lowland wet grassland adjacent
to tidal reaches of estuaries.  No national survey exists of
wet grassland as here defined, or indeed of coastal grazing
marsh or lowland wet grassland separately, so detailed
inter-region comparisons are not possible.
Coastal grazing marsh is a distinctive habitat consisting
of low-lying grassland drained by a series of ditches that
may be either brackish or freshwater.  Much grazing marsh
was formed by the enclosure of saltmarsh behind sea walls.
Smaller areas of freshwater grazing marsh have been
created landward of natural barriers such as sand dunes or
shingle beaches.  Wet grassland sites may remain wet
throughout the year and may be managed for stock grazing
and/or as hay meadow. 
The steep, rocky character of the coasts of Devon and
Cornwall has precluded the development of wet grassland
along much of the western part of the region.  However,
adjacent to the Severn Estuary there are extensive areas of
wet grassland, including two of the most important areas of
wet grassland in the British Isles - the Somerset Levels on
the south bank and the Gwent Levels on the north.  These
levels are nationally important areas of wet grassland for
their extent, the proportion of the national resource they
represent and the rare birds, plants and invertebrates that
they support.  This national importance is recognised by the
designation of seven SSSIs on the Somerset Levels and six
SSSIs on the Gwent Levels, the latter covering more than
4,500 ha.  The Somerset Levels and Moors Environmentally
Sensitive Area (ESA) represents some 27,000 ha of lowland
grassland contiguous with coastal wet grassland.  There are
also areas of wet grassland on the shores of the upper
Severn Estuary in Avon and Gloucestershire and small areas
associated with the Taw-Torridge Estuary in north Devon.  
Dargie (1993) estimated that there was a total of 
63,499 ha of lowland wet grassland in south-west England,
of which an estimated 41,275 ha were in Somerset and
11,122 ha in Avon.  The lowland wet grassland of these two
counties (most of which is grazing marsh) therefore
comprises approximately 80% of the lowland wet grassland
resource of south-west England, and approximately one
quarter of that in England.  The Gwent Levels represent
over half the lowland wet grassland in Wales.  The lowland
wet grassland resource of Region 11 is therefore important
in the national context. 
3.5.2  Important locations and species
Table 3.5.1
lists the locations of wet grassland sites in the
region, shown on 
Map 3.5.1
.  
Despite similarities, the levels of Somerset and Gwent on
either side of the Severn Estuary have distinct differences.
Much of the Somerset Levels remains under pasture, with
some fields retaining grasslands of conservation value.  By
contrast, the Gwent Levels have experienced considerable
agricultural improvement, with much of the land turned
Region 11  Chapter 3  Terrestrial coastal habitats
54
3.5  Wet grassland
Dr H.T. Gee
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Region 10
Region 12
5°W
Wet grassland site
Map 3.5.1 
Wet grassland sites (numbers refer to 
Table 3.5.1
) in the
region.  Source: Dargie et al. (1994).
over to improved pasture or arable use.  Patches of semi-
improved grassland of higher conservation value do
however, remain, often comprising areas of National
Vegetation Classification (NVC - Rodwell (1995))
community MG5 crested dog’s-tail Cynosurus cristatus -
common knapweed Centaurea nigra grassland, which is
typical of the habitat.  These include grass communities
containing the nationally scarce saltmarsh grass species
bulbous foxtail Alopecurus bulbosus.  
Some parts of the Somerset Levels, particularly those
near the shoreline, such as Catsford Common, Wall
Common, Pawlett Hams and the Huntspill Level, show a
distinct maritime influence.  Pawlett, Wickmore and
Northmore all have brackish back ditches, and Wall
Common experiences occasional inundation by the sea,
which has led to the development of unusual plant
communities in the soaks and gutters of the remnant tidal
creek system.  In the Somerset Moors and the Gordano
Levels (Avon), further inland, the wet grassland overlies
peat; most of the grassland here developed from freshwater
marsh.  The Gordano Levels also experience considerable
calcareous influence, which gives rise to vegetation
communities different from those found on the Somerset
Moors.  At Pennsylvania Fields, Gloucestershire, inundation
on spring tides has led to the development of communities
of a saltmarsh character containing saltmarsh rush Juncus
gerardi and sea arrowgrass Triglochin maritima and brackish
ditches supporting brackish water-crowfoot Ranunculus
baudotii.  The Gordano Levels have retained grasslands of
significant conservation value, including areas of
mesotrophic grassland and fen-mire communities.
The ditch communities of the region’s wet grasslands are
of considerable regional and national significance.
Nationally rare species found on the Somerset Levels
include brown beak-sedge Rhynchospora fusca, brown
galingale Cyperus fuscus, short-leaved water-starwort
Callitriche truncata and cut-grass Leersia oryzoides.  The
nationally notable fen pondweed Potamogeton coloratus and
whorled water-milfoil Myriophyllum verticillatum are both
present on the Gordano Levels.  The Avon Levels between
Weston-super-Mare and Clevedon are designated as SSSIs

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