Add below-ground organic matter: freshwater marshes

Overall effectiveness category No evidence found (no assessment)
Number of studies: 0
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Effectiveness

not assessed
Certainty

not assessed
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not assessed

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Background information and definitions

This action involves adding organic matter (i.e. remains or waste products of living organisms) below the ground surface, for example by mixing it into the sediment or placing it into holes. Specific substances than can be used include compost, sewage sludge, wood chips and seaweed extract.

The soil organic matter content of wetland soils may be reduced by disturbance. For example, drainage allows oxygen into the soil, whilst reprofiling removes surface layers rich in organic matter (Bruland et al. 2006). Organic matter can be an important component of wetland soils. It directly supplies nutrients to growing plants, supplies carbon and energy to soil organisms, helps bind the soil together, retains water during dry periods, and mediates soil temperature (Donahue et al. 1983; Weil & Brady 2016). Adding carbon-rich organic materials can indirectly modify nutrient availability by stimulating microbial activity, and so could help to manage invasive species where they benefit from an excess of certain nutrients (Reever Morghan & Seastedt 1999; Tilman et al. 1999; Perry et al. 2004).

To be summarized as evidence for this action, studies must evaluate the effects of adding organic matter without adding living vegetation. The organic matter should be used to help or manage existing vegetation, such as remnant patches of vegetation, or seedlings that germinate from seeds already present.

^{Bruland G.L., Richardson C.J. & Whalen S.C. (2006) Spatial variability of denitrification potential and related soil properties in created, restored, and paired natural wetlands. Wetlands, 26, 1042–1056.}

^{Donahue R.L., Shickluna J.C. & Robertson L.S. (1983) Soils: An Introduction to Soils and Plant Growth, Fifth Edition. Prentice-Hall, Englewood Cliffs, NJ, USA.}

^{Perry L.G., Galatowitsch S.M. & Rosen C.J. (2004) Competitive control of invasive vegetation: a native wetland sedge suppresses Phalaris arundinacea in carbon-enriched soil. Journal of Applied Ecology, 41, 151–162.}

^{Reever Morghan K.J. & Seastedt T.R. (1999) Effects of soil nitrogen reduction on nonnative plants in restored grasslands. Restoration Ecology, 7, 51–55.}

^{Tilman E.A., Tilman D., Crawley M.J. & Johnston A.E. (1999) Biological weed control via nutrient competition: potassium limitation of dandelions. Ecological Applications, 9, 103–111.}

^{Weil R.R. & Brady N.C. (2016) The Nature and Properties of Soils, Fifteenth Edition. Pearson, USA.}

Key messages

We found no studies that evaluated the effects, on vegetation, of adding below-ground organic matter to restore or create freshwater marshes.

‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.

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.

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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This Action forms part of the Action Synopsis:

Marsh and Swamp Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Add surface mulch: freshwater marshes Action Link	No evidence found (no assessment)	0	Synopsis Link
Add below-ground organic matter: brackish/salt marshes Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Disturb soil/sediment surface: freshwater swamps Action Link	No evidence found (no assessment)	0	Synopsis Link