Restoration of dredged canals in wetlands: a comparison of methods

Published source details Baustian J.J., Turner R.E., Walters N.F. & Muth D.P. (2009) Restoration of dredged canals in wetlands: a comparison of methods. Wetlands Ecology and Management, 17, 445-453.
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This study is summarised as evidence for the following.

	Action	Category
	Backfill canals or trenches: freshwater marshes Action Link

Backfill canals or trenches: freshwater marshes

A replicated, paired, site comparison study in 2005 of two backfilled canals in a freshwater marsh in Louisiana, USA (Baustian et al. 2009) reported that they both developed some marsh vegetation within three years, but with a different relative abundance of key plant species to natural marshes. Statistical significance was not assessed. Three years after backfilling, marsh vegetation coverage was 65% on former spoil areas but only 20–25% within each canal. The relative abundance of plant species differed between former spoil areas and adjacent natural marshes. In particular, alligatorweed Alternanthera philoxeroides was more dominant on former spoil areas (23–37% of vegetation) than in natural marsh (6–9% of vegetation). The opposite was true for spikesedge Eleocharis sp. (former spoil areas: 0–30%; natural marsh: 23–73%). Methods: In early 2002, two shipping canals were dammed and adjacent spoil was returned to the channels. One canal received additional sediment from a nearby lake. The canals were not completely filled and adjacent spoil areas were not entirely levelled. In 2005, aerial photographs were taken to estimate vegetation coverage. Vegetation was also surveyed in ten 1-m² quadrats/canal: five on former spoil areas (including marsh and non-marsh vegetation) and five in adjacent undisturbed marsh.

(Summarised by: Nigel Taylor)