Study

What factors determined restoration success of a salt marsh ten years after de-embankment?

  • Published source details Chang E.R., Veeneklaas R.M., Bakker J.P., Daniels P. & Esselink P. (2016) What factors determined restoration success of a salt marsh ten years after de-embankment?. Applied Vegetation Science, 19, 66-77.

Actions

This study is summarised as evidence for the following.

Action Category

Facilitate tidal exchange to restore/create brackish/salt marshes from other land uses

Action Link
Marsh and Swamp Conservation

Exclude or remove livestock from historically grazed brackish/salt marshes

Action Link
Marsh and Swamp Conservation
  1. Facilitate tidal exchange to restore/create brackish/salt marshes from other land uses

    A before-and-after study in 1987–2011 aiming to restore a brackish/salt marsh on grassland in the Netherlands (Chang et al. 2016) reported that within ten years of restoring regular tidal exchange, marsh plant communities had developed. Before intervention, the site was a grassland containing 35–70% (depending on the elevation) of the target marsh species (typical of brackish or saline marshes in the region). After 10 years, the site was completely covered by a range of brackish and saline marsh plant communities, each containing 78–96% of the target marsh species. Of the 23 target species, only common reed Phragmites australis was not found along any surveyed transects – but it was noted elsewhere in the site. Methods: Between 1997 and 2001, regular tidal exchange (i.e. more than just high spring tides and storm surges) was restored to grassland behind an embankment: first (1997) by opening two culverts, then (2000) by excavating creeks and filling drainage ditches, and finally (2001) by creating three breaches, each 20–40 m wide, in the embankment. Plant communities were assessed from maps made 14 years before and up to 10 years after breaching. Plant species were recorded in three permanent transects (each containing 250–310 contiguous 10 x 10 m cells) one year before and up to 10 years after breaching.

    (Summarised by: Nigel Taylor)

  2. Exclude or remove livestock from historically grazed brackish/salt marshes

    A replicated, paired, controlled study in 2002–2011 in a historically grazed brackish/salt marsh in the Netherlands (Chang et al. 2016) reported that the effects of excluding livestock on plant community composition, after nine years, depended on the elevation/wetness of plots. In higher, well-drained areas near to tidal creeks, exclusion plots developed a different plant community (dominated by sea couch grass Elytrigia atherica) to grazed plots (variable marsh communities). In lower, wetter areas further from creeks, a range of marsh plant communities developed in both exclusion and grazed plots with no clear distinction between the treatments. All data were reported as graphical analyses. The statistical significance of differences was not assessed. Methods: In spring 2002, twelve 10 x 25 m plots in a historically grazed coastal marsh were fenced to exclude livestock. The rest of the marsh remained grazed by cattle and horses during the summer. Regular tidal influx had been restored to the marsh over the previous five years. In summer 2011, cover of every plant species was estimated in seventy-two 4 x 4 m quadrats: three inside and three outside each exclosure.

    (Summarised by: Nigel Taylor)

Output references
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