Create mounds or hollows before planting trees/shrubs: brackish/saline wetlands

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

Study locations

Key messages

  • One study evaluated the effects, on vegetation, of creating mounds or hollows in brackish/saline wetlands before planting trees/shrubs. The study was in Brazil.








  • Survival (1 study): One replicated, controlled study in a degraded coastal swamp in Brazil reported that planting tree seedlings into mounds had mixed effects on survival over three years, depending on the species.
  • Growth (1 study): The same study reported that tree seedlings planted into mounds typically grew at a similar rate, over three years, to seedlings planted at ground level. Growth was measured in terms of diameter, height and canopy area.

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, controlled study in 2002–2005 in a degraded coastal swamp in southeast Brazil (Zamith & Scarano 2010) reported that creating mounds before planting tree seedlings had mixed effects on their survival over three years, but typically had no significant effect on growth. Planting into mounds rather than at ground level increased survival for two of five species (mounds: 70–77%; ground level: 57–67%), reduced survival for two species (mounds: 57–67%; ground level: 63–73%) and had no effect on survival of one species (100% in mounds or at ground level). Statistical significance of these survival results was not assessed. In 11 of 15 comparisons, growth rates were statistically similar for seedlings planted in mounds and at ground level. In the other four comparisons, seedlings planted in mounds grew more, or shrunk less, than seedlings planted at ground level (see original paper for data). Methods: In May 2002, sixty seedlings of each of five tree species were planted, 1.5 m apart, into a degraded coastal swamp. Thirty seedlings/species were planted into created mounds (10 cm high). Thirty seedlings/species were planted at ground level. All seedlings received 30 L of manure. Invasive trees and grasses were removed from the swamp before planting. Seedling survival was monitored until May 2005. Seedling diameter, height and canopy area were measured in August 2002 and August 2005.

    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?

List of journals searched by synopsis

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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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