Disturb soil/sediment surface: brackish/salt marshes

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

Study locations

Key messages

  • One study evaluated the effects, on vegetation, of disturbing the surface of brackish/salt marshes. The study was in the USA.


  • Community composition (1 study): One replicated, paired, site comparison study of brackish/salt marshes in the USA reported that marshes disked every spring for at least six years (and drawn down during spring/autumn) shared only 24–34% of plant species with marshes that were not disked (or drawn down).
  • Overall richness/diversity (1 study): The same study found that overall plant species richness and diversity were similar in managed marshes (disked every spring and drawn down during spring/autumn, for at least six years) and unmanaged marshes (neither disked nor drawn down).




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, paired, site comparison study in 2007–2009 of eight brackish/salt marshes in Texas, USA (Fitzsimmons et al. 2012) found that managed marshes (disked every spring, along with a spring/autumn drawdown) and unmanaged marshes (subjected to neither of these interventions) had few plant species in common, but had similar overall plant species richness and diversity. Only 24–34% of plant species were found in both managed and unmanaged marshes (reported as a similarity index). However, both marsh types had statistically similar plant species richness (six of six comparisons; managed: 12–21 species/marsh; unmanaged: 8–18 species/marsh) and plant diversity (six of six comparisons; data reported as a diversity index). Methods: In autumn, winter and spring 2007/2008 and 2008/2009, vegetation was surveyed in four pairs of managed and unmanaged marshes (fifty-six 1-m2 quadrats/marsh, placed along transects). In the managed marshes, the soil surface was disked every spring for 6–9 years. The managed marshes had also been impounded to control water levels and salinity (drawdown each spring-autumn). The study does not distinguish between the effects of three interventions. All marshes were grazed each summer and burned every three years. The marshes were brackish in 2007/2008 (managed: <2 ppt; unmanaged: <10 ppt) but saline in 2008/2009 following a hurricane and storm surge (e.g. average salinity in managed marshes: 20 ppt).

    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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