Use cutting/mowing to control problematic herbaceous plants: brackish/salt marshes

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

Study locations

Key messages

  • One study evaluated the effects, on vegetation, of cutting/mowing problematic herbaceous plants or small shrubs in brackish/salt marshes. The study was in the USA.


  • Overall richness/diversity (1 study): One replicated, randomized, paired, controlled study in a saltgrass-dominated marsh in the USA found that mown and unmown plots had similar overall plant species richness after one year.


  • Overall abundance (1 study): One replicated, randomized, paired, controlled study in a saltgrass-dominated marsh in the USA found that mown and unmown plots had similar overall vegetation cover after one year.
  • Individual species abundance (1 study): The same study found that six dominant herb species, other than the species being controlled, had similar cover in mown and unmown plots after one year.


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 study in 1992–1993 in an ephemeral brackish marsh dominated by saltgrass Distichlis spicata in California, USA (De Szalay & Resh 1997) found that mown and unmown plots had similar plant species richness, similar overall vegetation cover, and similar cover of dominant plant species. After one year, overall plant species richness did not significantly differ between mown plots (3.2 species/m2) and unmown plots (3.1 species/m2). The same was true for cover of vegetation overall (mown: 98%; unmown: >99%), saltgrass (mown: 93%; unmown: 99%) and each of six other dominant herb species (mown: 0–7%; unmown: 0–5%). However, mown plots did contain a greater density of saltgrass (4,070 stems/m2) than unmown plots (1,770 stems/m2). Density was not reported for the other six dominant herb species. Methods: Ten pairs of 100-m2 plots were established in an impounded brackish marsh, managed for waterfowl (autumn/winter flooding with spring/summer drawdown) but dominated by saltgrass. In August–September 1992, ten plots were hand-mown (one plot/pair; 50 m2/plot). Cuttings were not removed. The other plots were not mown. In August 1993, vegetation was surveyed in two 1-m2 quadrats/plot. Cover estimates included live and dead standing plants.

    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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