Abstract
The Medouie Creek wetland complex on Nantucket Island, MA was historically one contiguous salt marsh. Diking in the 1930s caused tidal restriction, creating a freshwater wetland colonized by Phragmites australis. To restore salt marsh habitat, the tidal restriction was removed and tidal salt water hydrology reestablished. Soil pore water salinity increased rapidly through the site with the majority of the marsh exhibiting salt marsh hydrology and higher salinities (25-30 ppt) eight years post-restoration. Extensive dieback of freshwater vegetation facilitated fairly rapid colonization by salt marsh vegetation, particularly adjacent to the culvert and marsh ditches. A non-metric multidimensional scaling (nMDS) analysis demonstrated that vegetation community composition was driven primarily by soil pore water salinity and marsh surface elevation. Eight years post-restoration, areas under 4 m elevation were dominated by salt marsh species while areas over 4 m retained freshwater vegetation. Unlike some other salt marsh restoration projects, salt marsh vegetation communities successfully established at Medouie primarily due to hydrological alteration and without the need for active revegetation or other restoration methods. P. australis stands were also significantly decreased. Given appropriate marsh conditions, altering hydrology alone to mimic functioning salt marsh hydrology may effectively drive vegetation succession and lead to ecologically functional salt marshes.
Published Version
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