Introduce fragments of non-woody plants: brackish/saline wetlands

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • Three studies evaluated the effects, on vegetation, of introducing fragments of emergent, non-woody plants to brackish/saline wetlands. Two studies were in one bog in Canada. One study was in China.

VEGETATION COMMUNITY

 

VEGETATION ABUNDANCE

  • Overall abundance (2 studies): Two replicated, paired, controlled, before-and-after studies in salt-contaminated bogs in Canada found that plots planted with rhizomes or sown with fragments of salt marsh herbs had similar overall vegetation biomass, after one year, to plots that had not been planted or sown.
  • Herb abundance (1 study): One replicated, paired, controlled, before-and-after studies in salt-contaminated bogs in Canada found that plots sown with fragments of salt marsh herbs had greater overall cover of the introduced species, after one year, to unsown plots. However, biomass of the introduced species did not significantly differ between sown and unsown plots.
  • Individual species abundance (2 studies): Two replicated studies (one also before-and-after) in brackish/saline wetlands in Canada and China simply quantified the abundance of herb species, over one year or growing season after planting herb fragments.

VEGETATION STRUCTURE

 

OTHER

  • Germination/emergence (1 study): One replicated study on a tidal flat in China reported that at least 25% of bulrush Scirpus mariqueter corms (bulb-like organs) produced shoots within the first growing season after planting.

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, controlled, before-and-after study in 2011–2012 in two salt-contaminated bogs in New Brunswick, Canada (Emond et al. 2016) found that plots planted with rhizomes of salt marsh herbs contained a similar overall vegetation biomass to unplanted plots. Plots were initially bare peat. After one year, total above-ground vegetation biomass did not significantly differ between plots planted with chaffy sedge Carex paleacea (150 g/m2), plots planted with prairie cordgrass Spartina pectinata (66 g/m2) and unplanted plots (122 g/m2). In the plots where it was planted, chaffy sedge biomass was 120 g/m2 and it had 9–17% cover. In the plots where it was planted, prairie cordgrass biomass was 24 g/m2, and it had 2–3% cover. Methods: In June 2011, forty-eight 9-m2 plots were established across the two bogs, in four blocks of twelve. Plugs of rhizomes and soil (5 cm diameter) from an adjacent salt marsh were added to 32 of the plots (eight plots/block; four with sedge rhizomes and four with cordgrass rhizomes). Phosphorous fertilizer and lime were each applied to one plot per treatment. In July 2012, vegetation cover was recorded in the central 4 m2 of each plot. Vegetation was cut from one 250-cm2 quadrat/plot, then dried and weighed. This study shared part of the experimental set-up used in (2).

    Study and other actions tested
  2. A replicated, paired, controlled, before-and-after study in 2011–2012 in two salt-contaminated bogs in New Brunswick, Canada (Emond et al. 2016) found that plots sown with salt marsh vegetation fragments developed greater cover of introduced herb species than unsown plots, but similar biomass of these species and vegetation overall. Before sowing, plots were bare peat. After one year, sown plots had greater cover of introduced herb species (i.e. the 15 species present at the donor site; 1–4%) than unsown plots (<1%). However, there was no significant difference between treatments in biomass of introduced species (sown: 12–14 g/m2; not sown: 0 g/m2) or vegetation overall (sown: 126–155 g/m2; not sown: 122 g/m2). Methods: In June 2011, forty-eight 9-m2 plots were established across the two bogs, in four blocks of twelve. Vegetation fragments from an adjacent salt marsh were added to 32 of the plots (eight plots/block; four in July, four in August). Phosphorous fertilizer and lime were each applied to half of the plots. In July 2012, vegetation cover was recorded in the central 4 m2 of each plot. Vegetation was cut from one 250-cm2 quadrat/plot, then dried and weighed. This study shared part of the experimental set-up used in (1).

    Study and other actions tested
  3. A replicated study in 2014 on a recently deposited tidal flat in eastern China (Hu et al. 2016) reported that planted bulrush Scirpus mariqueter corms (swollen underground stems, similar to bulbs) successfully emerged to produce above-ground parts. Over the first growing season after planting, the emergence rate of planted corms was at least 25–42% (depending on planting density, and based on the maximum number of seedlings observed at any one time). At the end of the growing season, planted areas contained 73–216 bulrush shoots/m2. The final shoot density was significantly greater where more corms had been planted. Methods: In March–April 2014, field-collected bulrush corms were planted into a recent accumulation of intertidal sediment in the Yangtze estuary. Three 400-m2 plots were each planted with a different density of corms: 15, 30 or 60 corms/m2. Corms were planted 5 cm deep. Bulrush seedlings and shoots were counted twice each month until October, in ten 4-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.

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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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