Comparison of natural and man-made salt marshes in Galveston Bay Complex, Texas

Published source details Webb J.W. & Newling C.J. (1984) Comparison of natural and man-made salt marshes in Galveston Bay Complex, Texas. Wetlands, 4, 75-86.
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This study is summarised as evidence for the following.

	Action	Category
	Deposit soil/sediment and introduce vegetation: brackish/salt marshes Action Link

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

A paired, site comparison study in 1978–1979 of four intertidal salt marshes in Texas, USA (Webb & Newling 1984) found that a created marsh – where cordgrasses Spartina spp. were planted and sown after depositing sediment – typically developed similar vegetation biomass and cordgrass of similar height to natural marshes, with mixed results for cordgrass density. Within four years, total above-ground vegetation biomass was statistically similar in created and natural marshes in 19 of 24 comparisons (for which created: 278–982 g/m²; natural: 132–1,102 g/m²). The average height of smooth cordgrass Spartina alterniflora was statistically similar in created and natural marshes in 15 of 21 comparisons (for which created: 34–124 cm; natural: 13–114 cm). In the other eight comparisons, all below mean high tide, cordgrass was taller in created marshes. The density of smooth cordgrass was similar in created and natural marshes in only 10 of 24 comparisons (for which created: 27–489; natural: 12–635 stems/m²). Its density was higher in created marshes in seven comparisons (all above mean high tide; created: 27–156; natural: 0–63 stems/m²) but lower in created marshes in seven comparisons (all below mean high tide; created: 192–489; natural: 396–814 stems/m²). Methods: Between August and November 1978 and 1979, vegetation was surveyed in one created and three natural salt marshes (six 0.5-m² quadrats at each of 3–5 tide levels/marsh). Marsh creation involved depositing sediment in 1975 then, in some areas, planting cordgrass sprigs in summer 1976 and sowing cordgrass seeds in spring 1977. All quadrats were in or near to planted/sown areas (not clearly reported). Biomass was dried before weighing. One site from this study was also included in (3). Some data from this study were included in (5).

(Summarised by: Nigel Taylor)