The effects of integrated marsh management (IMM) on salt marsh vegetation, nekton, and birds

Published source details Rochlin I., James-Pirri M., Adamowicz S.C., Dempsey M.E., Iwanejko T. & Ninivaggi D.V. (2012) The effects of integrated marsh management (IMM) on salt marsh vegetation, nekton, and birds. Estuaries and Coasts, 35, 727-742.
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This study is summarised as evidence for the following.

	Action	Category
	Facilitate tidal exchange to restore degraded brackish/salt marshes Action Link

Facilitate tidal exchange to restore degraded brackish/salt marshes

A replicated, before-and-after study in 2003–2008 of two brackish/salt marshes in an estuary in New York State, USA (Rochlin et al. 2012) found that after blocking drainage ditches and excavating tidal channels/pools to improve tidal exchange, one of two marshes experienced changes in plant community composition including a reduction in cover of common reed Phragmites australis. Before intervention, Marsh 1 was highly degraded. In all four years after intervention, the overall plant community composition along transects in this marsh was significantly different to the composition before (data reported as a graphical analysis). Species whose average cover increased included saltmarsh bulrush Schoenoplectus robustus (before: 0.0%; after: 9.0%) and smooth cordgrass Spartina alterniflora (before: 0.2%; after: 2.0%). Cover of both live and dead common reed declined (live: from 25% to 8%; dead: from 21% to 5%). There was no clear change in cover of saltmeadow cordgrass Spartina patens (before: 80%; after: 82%). Statistical significance of these cover results was not assessed. Marsh 2 was less degraded before intervention. It experienced no significant change in overall plant community composition after intervention (data not reported). Methods: Between 2004 and 2006, tidal exchange was restored in two degraded (ditched, tidally restricted and reed-invaded) 16–19 ha brackish/salt marshes. Most existing drainage ditches were filled and new tidal channels/pools were excavated. Additionally, to reduce habitat for mosquito breeding, some depressions in the high marsh were filled in. Vegetation was surveyed each autumn for 2–3 years before and 3–4 years after intervention, along 4–5 transects spanning each marsh.

(Summarised by: Nigel Taylor)