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Several studies have noted a recent reversal of this long-term trend in marsh-community dynamics by documenting sediments dominated by cordgrass remains overlying high-marsh sediments at several sites in southern New England (13–15).Two of these studies (13, 14) attributed the recent migration of cordgrass onto the high-marsh surface to the combined influence of changes in geomorphology associated with the September 21, 1938, New England Hurricane and increased rates of SLR.The timing of the initiation of cordgrass migration is coincident with an acceleration in the rate of sea-level rise recorded by the New York tide gauge.These results suggest that increased flooding associated with accelerating rates of sea-level rise has stressed high-marsh communities and promoted landward migration of cordgrass.Coeditor of Proceedings of the Sixth International Conference on Radiocarbon and Tritium Dating. Karabinos Thomas Edvard Krogh - Director, Geochronology Laboratory, Royal Ontario Museum, Toronto. Monitoring plant zonal boundaries in two New England salt marshes revealed that low-marsh cordgrass rapidly moved landward at the expense of higher-marsh species between 19.In the Redfield model of marsh development (12), low marsh dominated by cordgrass accretes vertically and seaward over aggrading mud or sand flats.
Localized nutrient additions can cause a reversal in the competitive relationship between cordgrass and marsh hay resulting in cordgrass migration to higher elevations at the expense of marsh hay and increased cordgrass biomass (16).The ability of cordgrass to oxygenate substrates (11) allows this species to dominate frequently flooded lower-marsh elevations, whereas it is competitively excluded from higher elevations where soil oxygen content is higher.Existing salt marshes in New England developed during the last 4,000 years and have generally kept pace with moderate rates of SLR of about 1 mm/year (12). 100% Free Online Dating for Punjab Singles at Mingle2Our free personal ads are full of single women and men in Punjab looking for serious relationships, a little online flirtation, or new friends to go out with.