SURVEY AND COMPARISON 159
area where salt-pans are developing, and Juncus maritimus
Lam. is found once in an area which does not appear to be
distinguished in any way from the rest of the marsh. There
is also one patch of Artemisia maritima L. fairly close to the
sea wall.
Differences in flora due to a lower level of marsh are seen
in various places in the area. At Site 15 the mudbank has
been lowered, due to the presence of a house-boat until two
years ago, and here Salicornia species are now dominant.
New marsh is being built up at the edges of the existing
banks, and is still at a slightly lower level at Site 11. Here
Salicornia species are the main colonists, and round patches
of Spartina Townsendii are also fairly prominent. Aster
Tripolium and Suaeda maritima are again associated, but
there is no Puccinellia in these areas. Presumably, this
species prefers a more stabilised substratum, or is unable to
withstand a longer period of immersion. The other four
species represented in this area all have a more upright
habit than that of Puccinellia. Averages of quadrats on
Site 11 show the following percentages :—
Salicornia spp. ... ... ... 62.0%
Spartina Townsendii ... ... 13.0%
Aster Tripolium ...... 7.0%
Suaeda maritima ... ... 4.5%
The distribution of species on the main salt marsh is
illustrated by the Transect at Site 12. (See fig. 4, page 160.)
The salt marsh to the south of Two Tree Island appears
to be less well-developed than that adjacent to the main-
land. This is probably because the Two Tree saltings are
not as well protected. Hadleigh Ray is broad and deep, and
the strong currents will not allow for the deposition of much
silt. Where the marsh is more built-up at the eastern end,
Halimione portulacoides occurs, but otherwise the main
colonist of these saltings is Spartina Townsendii. Towards
the western end of the island this occurs in small, round
patches, but adjacent to the middle of the island and east-
wards from this, it occupies vast areas, occurring in many