Add salt to control problematic plants: brackish/salt marshes

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

35%
Certainty

30%
Harms

5%

Calculating overall effectiveness category

Background information and definitions

Direct and temporary application of salt or salty water to marshes, for example by spreading or spraying, may kill or reduce the growth of problematic plants that cannot tolerate high salinities. Salt may also be more cost effective than other control methods, such as hand removal or herbicide application (Kuhn & Zedler 1997). Caution: This action may have long-term and widespread impacts on native plants and other organisms, both in the focal site and nearby ecosystems (Alluvium 2013). So, it may be best to use short-term and targeted applications (Kuhn & Zedler 1997).

For this action, “vegetation” refers to overall or non-target vegetation. Studies that only report responses of target problematic plants have not been summarized.

^{Alluvium (2013) Investigation of Alternative Options to Control Phragmites at Reedy Lake. Report P112088_R01_V03 for the Corangamite Catchment Management Authority.}

^{Kuhn N.L. & Zedler J.B. (1997) Differential effects of salinity and soil saturation on native and exotic plants of a coastal salt marsh. Estuaries, 20, 391–403.}

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.

VEGETATION COMMUNITY

VEGETATION ABUNDANCE

VEGETATION STRUCTURE

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

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
Referenced paper
Kuhn N.L. & Zedler J.B. (1997) Differential effects of salinity and soil saturation on native and exotic plants of a coastal salt marsh. Estuaries, 20, 391.

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?

List of journals searched by synopsis

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This Action forms part of the Action Synopsis:

Marsh and Swamp Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Use covers/barriers to control problematic plants: freshwater marshes Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Use grazing to control problematic plants: freshwater swamps Action Link	No evidence found (no assessment)	0	Synopsis Link
Add salt to control problematic plants: brackish/salt marshes Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link