Add salt to control problematic plants: brackish/salt marshes

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • One study evaluated the effects, on vegetation, of directly adding salt to control problematic plants in brackish/salt marshes. The study was in the USA.






  • Height (1 study): One replicated, randomized, paired, controlled, before-and-after study in a salt marsh in the USA found that adding salt to control invasive beardgrass Polypogon monspeliensis had no significant effect on the height the dominant native glasswort Salicornia subterminalis.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated, randomized, paired, controlled, before-and-after study in 1994–1995 in an estuarine salt marsh in California, USA (Kuhn & Zedler 1997) found that adding salt to control invasive annual beardgrass Polypogon monspeliensis had no significant effect on the height of the native dominant glasswort Salicornia subterminalis. Over three months, glasswort plants were a similar height in plots with or without added salt (salt: 31–34 cm; no salt: 32–34 cm). The same was true before intervention (salt: 31–34 cm; no salt: 33 cm). After three months, there were fewer beardgrass shoots in plots with added salt than plots without (data reported as density classes). Methods: In December 1994, thirty-two 1-m2 plots were established (in eight sets of four) on a beardgrass-invaded, intertidal salt marsh. Between December and February, sea salt was sprinkled onto the surface of 24 plots. One random plot/set received each monthly dose: 850 g, 1,700 g or 3,400 g. No salt was added to the final eight plots. Vegetation was surveyed before salt additions began (December 1994) and for three months after (January-March 1995). Three individual glasswort plants/plot were measured throughout the study.

    Study and other actions tested
Please cite as:

Taylor N.G., Grillas P., Smith R.K. & Sutherland W.J. (2021) Marsh and Swamp Conservation: Global Evidence for the Effects of Interventions to Conserve Marsh and Swamp Vegetation. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

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Marsh and Swamp Conservation

This Action forms part of the Action Synopsis:

Marsh and Swamp Conservation
Marsh and Swamp Conservation

Marsh and Swamp Conservation - Published 2021

Marsh and Swamp Synopsis

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