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Saltmarsh definition
Definition UK Biodiversity Action Plan - "Coastal saltmarshes in
the UK (also known as 'merse' in Scotland) comprise the upper, vegetated portions
of inter tidal mudflats, lying approximately between mean high
water neap tides and mean high water spring tides. For the purposes
of this action plan, however, the lower limit of saltmarsh is defined as the
lower limit of pioneer saltmarsh vegetation (but excluding seagrass Zostera
beds) and the upper limit as one metre above the level of highest astronomical
tides to take in transitional zones."
"The establishment of halophytic
(salt-tolerant) plants on sheltered tidal flats is the first stage in the colonisation
of this highly specialised community. Accumulations of sediment around the first
colonisers allow other species to invade and the process of succession takes
place, leading to sometimes complex stands of vegetation which develop out of
reach of all but the highest tides. Saltmarshes are, as their name implies,
habitats dominated by species which are tolerant of inundation by saline water.
A definition is:
"Natural or semi-natural halophytic grassland and dwarf brushwood on
the alluvial sediments bordering saline water bodies whose water level fluctuates
tidally or non-tidally." (Beeftink 1977)
This definition also encompasses halophytic
communities occurring in micro-tidal seas such as the Baltic and Mediterranean,
on sandy substrates in transitional zones adjacent to sand dunes and brackish
water ditches and dykes in areas of coastal grazing marsh and in saline lagoons.
It is less relevant to salt marsh communities which occur on rocky shores where
sediment deposition is virtually absent or on exposed cliffs where salt spray
is driven inland (Doody 2001).
Caveat: Inland halophytic communities, associated with salt lakes
or upwelling from underground salt deposits and salt steppes, are not included
in this guide.
References
Beeftink, W.G.
1977.
Salt-marshes.
In: The Coastline, ed.Barnes, R.S.K.John Wiley & Sons, Chichester, 93-122.
Doody, J.P.
2001.
Coastal Conservation and Management: an Ecological Perspective. Kluwer, Academic Publishers, Boston, USA, 306 pp.
Conservation Biology Series, 13
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