Jncc coastal Directories Project Region 11 The Western Approaches

3.6.1  Introduction
There are 1,870 ha of saltmarsh in Region 11, representing
approximately 8% of the resource on the West Coast and 4%
of that in Britain (
Table 3.6.1
).  Of this, more than 1,400 ha is
found in the Severn Estuary and Bridgwater Bay.  Elsewhere
in the region, only the Fal complex and Taw-Torridge
Estuary contain more than 50 ha of saltmarsh.
Approximately 28% of the coastlines of Avon,
Gloucestershire and Gwent support saltmarsh, compared to
12% in Somerset, 9% in South Glamorgan and 10% in the
whole of Devon and Cornwall (the southern parts of the
coastline of these two counties being in Region 10).  In Mid
Glamorgan only 6% of the coastline is fronted by saltmarsh.
Table 3.6.1
shows the areas of saltmarsh vegetation
recorded in the national survey (Burd 1989 a-d).  More than
40% of the saltmarsh area in the region was cord-grass
Spartina spp. marsh, a much greater proportion than on the
west coast or in Britain as a whole (15-16%).  Whilst Spartina
still forms an important pioneer saltmarsh community in
the region, this figure for the proportion of Spartina marsh is
now an over-estimate, as the species has certainly decreased
in area since the date of the survey (see 
section 3.6.4
).
3.6.2  Important locations and species
Saltmarsh sites surveyed during the national survey (Burd
1989a-d) are listed in 
Table 3.6.2
and shown on
Map 3.6.1
.
This survey did not include the Isles of Scilly; however,
there are no significant areas of saltmarsh vegetation on the
islands (J.P. Doody pers. comm.).  In Devon and Cornwall,
the high energy coastline means that there are only small
saltmarshes, restricted to sheltered sites.  Most of the
saltmarshes in the region are of the estuarine fringing type,
but ria head (Fal and Helford River), open embayment
(Bridgwater Bay) and back-barrier (Berrow/Bridgwater Bay
and Taw-Torridge) types are also found (Pye & French
1993).  At Porlock, there is saltmarsh behind the shingle
Region 11  Chapter 3  Terrestrial coastal habitats
58
3.6  Saltmarsh
Dr M.I. Hill
Table 3.6.1  
Areas (ha) of saltmarsh communities in context
Spartina
Pioneer
Low-
Mid-
Drift-
Upper 
Transition
Wet
Total
% of total
mid
upper
line
swamp
depression
in region
Cornwall (part)
14
28
38
70
2
19
15
0
187
10
Devon (part)
48
51
95
32
9
4
0
0
240
13
Somerset
340
6
8
123
6
16
0
0
499
27
Avon
159
0
32
108
14
0
0
0
314
17
Gloucestershire
28
1
20
196
12
1
0
0
258
14
Gwent
155
0
28
55
28
0
0
0
267
14
South Glamorgan
36
0
7
44
0
0
4
0
91
5
Mid Glamorgan
0
0
5
10
0
0
1
0
15
1
Region 11
781
85
234
638
71
41
19
0
1,870
100
England
5,166
2,641
10,299
9,948
1,493
686
833
0
31,533
-
Wales
1,681
468
1,555
2486
267
202
89
0
6,748
-
West Coast of GB
3,487
1,340
4,159
11,270
473
410
1,327
1
22,582
8
Great Britain
6,948
3,470
12,353
16,042
1,824
1,475
1,670
2
44,370
4
Source: National Saltmarsh Survey (Burd 1989a-d).  Key: - = % not calculated.  Note: areas have been rounded to the nearest whole hectare;
percentages have been rounded up to whole numbers.
Camel Estuary
The Gannel
Hayle Estuary
Fal Estuary
Helford River
River Ogmore
East Aberthaw
Severn
Estuary
Bridgwater Bay/River Parrett
Taw–
Torridge
Region 10
Region 12
5°W
Map 3.6.1
Saltmarsh sites surveyed in National Saltmarsh Survey
(see 
Table 3.6.2
).  Source: JNCC Coastal Database.
beach, maintained by seawater percolation through the
ridge.  In the Severn Estuary, substantial areas of saltmarsh
have been subject to land-claim since Roman times, leaving
a narrow discontinuous saltmarsh fringe. 
Sites of Special Scientific Interest (SSSIs) containing
saltmarsh in the region are listed in 
Table 3.6.3
(see also
Chapter 7
).  
There is no saltmarsh zonation that can be said to be
characteristic of the region, as the marshes vary greatly in
structure, age, sediment type and management.  Common
cord-grass Spartina anglica is the main pioneer species and
the low-mid marsh is most usually of common saltmarsh-
grass Puccinellia maritima.  Mid to upper marsh vegetation is
frequently dominated by common saltmarsh-grass, red
fescue Festuca rubra, saltmarsh rush Juncus gerardi and
creeping bent Agrostis stolonifera.  Upper marsh swamps of
sea club-rush Scirpus maritimus and common reed
Phragmites australis are spreading at the landward edge of
ungrazed or less heavily grazed marshes.  At Bridgwater
Bay, for example, a new saltmarsh was formed when
Spartina became established in 1929, but since the 1950s the

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