Add salt to control problematic plants: brackish/salt marshes
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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.
Related actions: Facilitate tidal exchange to restore degraded marshes.
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.
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