Tidal Marsh Restoration and Creation.

Tidal salt and brackish marshes occur in the upper intertidal zone of sheltered coastal areas such as estuaries, bays, and behind barrier islands. Periodic, predictable inundation by bidirectional tidal flow is a defining characteristic of these systems. The distinct zonation of plant communities and the sharp upper and lower elevation limits of emergent marsh vegetation are affected by the tidal regime at each site. The hydrology of tidal marshes may also be influenced by rainfall, river flow, wind-driven tides, and by runoff and seepage from adjacent uplands. Inundation is the dominant abiotic variable affecting edaphic factors such as salinity, waterlogging, redox potential, pH, and plant available nutrients. Tidal marshes provide valuable ecosystem services including habitat for fish and wildlife, support for the estuarine food web, capture and storage of carbon, improving water quality by filtration of sediments, removal of excess nutrients and other pollutants, storage of flood water, and shoreline stabilization.  The loss and degradation of tidal marshes due to development activities, led to an interest in restoring or creating new marshes to mitigate losses of ecosystem services.

Field research in a variety of coastal environments has developed and documented methods that result in successful restoration and creation of marshes. Important considerations are site selection, assessment of reference sites to determine plant species, soils and elevation targets, design and construction, obtaining plant propagules, proper planting methods, plant spacing, providing plant nutrients with fertilizers if needed, and maintenance. Evaluation of functional equivalence of restored and created tidal marshes indicates that by applying sound principles of ecological engineering these systems have the same appearance and, with time, provide many of the same ecosystem services as natural marshes.