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Saltmarsh States and Values - summary
Two key issues have been identified which help to define the states and values
of saltmarshes when considering restoration, namely:
- Grazing management which has a significant effect on the vegetation and
the nature of the associated species. Four
states are identified for saltmarsh vegetation which are determined
by stock densities;
- Erosion and/or accretion which changes the surface (vertical) and the (horizontal)
stability of the saltmarsh. Three
states are identified describing the physical state of the saltmarsh.
The values of each of these states are considered under separate headings,
namely:
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General guidance: These two series of states appear to be largely
independent of each other. However, there is some evidence from the USA
to suggest that grazing by vertebrates can reduce the growth of marsh
and lead to instability (Ford & Grace
1998) though this has not been studied in the UK. On the east coast
of the United States Anser caerulescens
(snow goose) may locally put enough pressure on a saltmarsh to remove
most of the vegetation over just one season (Daiber
1982).
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References
Daiber, F.C.
1982.
Animals of the Tidal Marsh. Van Nostrand Reinhold, New York.
Ford, M.A. & Grace, J.B.
1998.
Effects of vertebrate herbivores on soil processes, plant biomass, litter accumulation and soil elevation changes in a coastal marsh.
Journal of Ecology, 86/6., 974-982.
Abstract...
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