Salt marsh elevation

The emissions from all soil sites other than the . altemiflora marsh followed a pattern that was consistent with release of microbial metabolites from the soil surface. H2S and DMS were the predominant species found, with emission rates 10-100 times greater than those of CS2 and DMDS. Peak emissions of all compounds were measured in the early afternoon, corresponding to the maximum soil temperature. No effects were found due to the extent of vegetation coverage. Die difference between these sites and the . altemiflora sites provides indirect evidence for the role of DMSP cleavage in the release of DMS from the tissues of the , altemiflora. Elevated concentrations of DMSP have been reported to occur in the leaves of . altemiflora. when compared to other American salt-marsh species (6). 

The low emission rates measured in this study indicate that salt marshes are a minor source of sulfur to the global atmosphere. Furthermore, our measurement of deposition rates show the potential for losses to the same soil surfaces at times of elevated atmospheric concentration. 

Scarton, F., Day, J.W., Rismondo, A., Cecconi, G., and Ave, D. (2000) Effects of an intertidal sediment fence on sediment elevation and vegetation distribution in a Venice (Italy) lagoon salt marsh. Ecol. Eng. 16, 223-233. 

Rogers, J., Harris, J., and Valiela, I. (1998). Interaction of nitrogen supply, sea level rise, and elevation on species form and composition of salt marsh plants. Biol. Bull. 195, 235—237. 

Fig. 7. Ranges of elevation in which different plant species occur on a salt marsh near Guilford, Connecticut. Datum is mean sea level (MSL). The tidal ranges shown are the highest astronomical tide (HAT), mean high-water springs (MHWS), and mean high-water neaps (MHWN).

Fio. 8. Average immersion time as a function of elevation for the salt marsh of Fig. 7. 

Fig. 12. Comparison of salt-marsh and tide-gauge records. The ages of salt-marsn peat calculated from the distribution of excess "Pb are plotted as horizontal bars of length 2

Saltwater intrnsion is a dominant edaphic factor that inflnences the survival, growth, and species composition in coastal wetlands along the Louisiana Gnlf Coast. The net effect of sublethal salt stress is the redaction in growth especially in marsh soils with low bulk density or mineral content in the soil profile. For most species growing in salt and brackish marshes, elevated salinity does not create a favorable environment for growth and productivity (Figure 18.14). In fact, numerous... 

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