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2001). In the
Festuca rubra
zone, higher up the salt
marsh with less inundation, the rate of sedimentation
is lower than in the
P. maritima
zone (Andresen
et al
.
1990). A typical salt marsh zonation along the east
coast of the United States shows from the pioneer zone
towards higher elavation:
Spartina alternifl ora
,
S. patens
,
Juncus gerardi
and
Iva frutescens
(Bertness
et al
. 2009 ).
Sedimentation patterns show spatial variation. Over
comparatively wide marshes, a landward decrease of
sedimentation was found in seminatural mainland
marshes in Sussex, United Kingdom (Reed 1988),
along the Westerschelde, the Netherlands (Temmer-
man 2003), in a back barrier marsh at Skallingen,
Denmark (Bartholdy 1997) and in seminatural
marshes with sedimentation fi elds in Germany
(Schr ö der
et al
. 2002) and in the Dollard, the Nether-
lands (Esselink
et al
. 1998). Superimposed on the large-
scale differences from low to high marsh, the rate
of sedimentation also declines away from creeks and
ditches (Figure 19.1). Moreover, higher rates were
Creek B (750 m from intertidal mudflats)
r
2
= 0.88***
0.50
(a)
r
2
= 0.98**
0.45
0.40
0.35
r
2
= 0.94***
r
2
= 0.92*
0.30
0.25
20
(b)
r
2
= 0.95*
r
2
= 0.98***
16
12
8
4
0
30
20
10
0
10
20
30
seawall
intertidal mudflats
Distance (m)
Figure 19.1
(a) Levee development near a minor creek at a distance of 750 m from intertidal mudfl ats and (b) annual
vertical accretion rate (means ± S.E.M.) at different distances from a main creek as a function of the distance from the
intertidal mudfl ats. In (a):
•
, 1984;
, 1991. Points in the left-hand panel at higher elevations were located on the
neighbouring levee of the next minor creek. MHT, mean high tide. (Modifi ed from Esselink
et al
. 1998 . Reproduced by
permission of
Journal of Coastal Research
.)
