Study

Recommended design for more accurate duplication of natural conditions in salt marsh creation

  • Published source details Darnell T.M. & Smith E.H. (2002) Recommended design for more accurate duplication of natural conditions in salt marsh creation. Environmental Management, 29, 813-823.

Actions

This study is summarised as evidence for the following.

Action Category

Deposit soil/sediment and introduce vegetation: brackish/salt marshes

Action Link
Marsh and Swamp Conservation
  1. Deposit soil/sediment and introduce vegetation: brackish/salt marshes

    A replicated, before-and-after, site comparison study in 1991–1995 of seven salt marshes in Texas, USA (Darnell & Smith 2001) reported that areas of deposited sediment planted with marsh plants developed marsh vegetation, but that that the plant community composition differed from natural marshes after 2–4 years. Statistical significance was not assessed. After 2–4 years, 34–63% of each created marsh was covered by salt marsh vegetation; 1–35% was unvegetated salt pans and 16–30% was subtidal open water. The most abundant species was smooth cordgrass Spartina alterniflora (18–45% cover). For comparison, nearby natural marshes were composed entirely of salt marsh vegetation (52–71% of area) and unvegetated salt pans (29–48% of area). The most abundant species were saltwort Batis maritima (31–41% cover) and shoregrass Monanthochloe littoralis (5–47% cover). Smooth cordgrass was absent. Similarity in the overall plant community composition between created and natural marshes ranged from <1 to 36%. Methods: Four marshes were created on the Texas coast between 1991 and 1993. Dredged sediment was pumped into 2–7 ha cells, enclosed by levees. Once the sediment had settled, marsh vegetation was planted into the intertidal parts of each site (three sites: 12 herb and shrub species; one site smooth cordgrass only). The created marshes were designed to contain diverse habitats rather than to replicate the natural marshes exactly; they had a steeper gradient and were flooded more often than the natural marshes. The four created marshes, and three nearby natural marshes, were surveyed in 1995. Habitat coverage was mapped from aerial photographs. Plant species were recorded along transects at 200–303 points/site.

    (Summarised by: Nigel Taylor)

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