Removal of Salt-killed Vegetation during Tidal Restoration of a New England Salt Marsh: Effects on Wrack Movement and the Establishment of Native Halophytes

Abstract

A New England salt marsh undergoing tidal restoration was manipulated to improve halophyte seed dispersal and encourage the expansion of salt marsh plant communities. I created ten openings (150 m²) in an area of dead freshwater shrubs and common reed (Phragmites australis), which had been killed by saltwater inundation during tidal restoration. The dead plants presented a physical barrier to the upstream movement of waterborne seeds from halophyte species. Five of the openings were extended to the edge of the adjacent recovering salt marsh, providing a clear passageway into the plots cleared of barrier vegetation. Another five remained as isolated clearings and five uncut plots served as controls. The establishment of salt marsh plants was greatly enhanced by removing the barrier vegetation. While plots directly connected to the salt marsh yielded the highest numbers of new halophytes, isolated clearings also had a beneficial effect. These responses suggest that barrier vegetation removal can facilitate seed dispersal, colonization, and succession in a salt marsh habitat, and provides an effective alternative to standard restorative approaches such as artificial seeding and planting.