Add surface mulch before/after planting non-woody plants: freshwater wetlands

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

Study locations

Key messages

  • One study evaluated the effects, on vegetation, of mulching freshwater wetlands planted with emergent, non-woody plants. The study was in Australia.




  • Herb abundance (1 study): One replicated, randomized, paired, controlled study in floodplain swamps in Australia found that mulching with woodchips before planting native understory herbs either increased or had no significant effect on their overall cover, one year later.
  • Individual species abundance (1 study): The same study found that mulching with woodchips before planting native understory herbs reduced the cover of one problematic species (common reed Phragmites australis) one year later, but had no significant effect on another (reed canarygrass Phalaris arundinacea).


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 2014–2015 in two degraded floodplain swamps in Victoria, Australia (Greet et al. 2016) found that mulching plots with woodchips before planting native understory herbs increased their cover in one of the swamps, but had no significant effect in the other. Cover was monitored one year after planting. In one swamp, invaded by common reed Phragmites australis, mulched plots had higher cover of native understory herbs (26%) than unmulched plots (4%). The mulched plots also had lower reed cover (mulched: 40%; unmulched: 73%). In the other swamp, invaded by reed canarygrass Phalaris arundinacea, mulched plots had statistically similar cover of native understory herbs (3%) to unmulched plots (2%). Canarygrass cover was also similar between treatments (mulched: 96%; unmulched: 99%). Methods: In February–March 2014, four 100-m2 plots were established in each of two floodplain wetlands. All plots had been recently cut and sprayed with herbicide (to control common reed or reed canarygrass) and fenced to exclude large animals. Four plots (two random plots/swamp) were mulched with eucalypt Eucalyptus sp. woodchips. All plots were then planted with native understory herbs (3 plants/m2; species not reported), plus shrubs (1 plant/m2) and tree seedlings (1 plant/2 m2). Vegetation was surveyed in March 2015, in five 1-m2 quadrats/plot.

    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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