Introduce fragments of trees/shrubs: freshwater wetlands

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

25%
Certainty

20%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

This action involves introducing fragments of trees/shrubs to restore/create swamps. For trees/shrubs, fragments will most likely be unrooted cuttings. Vegetation fragments may be planted directly into the soil, or spread on the soil surface. Fragments may be obtained from plants raised in greenhouses/laboratories, or collected from natural sites (with potential damage to donor site; Laegdsgaard 2002).

Introduction of target vegetation might be useful in severely degraded or bare sites – which may lack remnant plants or seed banks to kick start revegetation with desirable species, and may be at risk of being taken over by undesirable species (Brown & Bedford 1997). It might also be useful in isolated wetlands, far from sources of marsh or swamp plant propagules. However, note that up-front costs can be high.

The effects of planting may be highly dependent on the environmental conditions in each study. Questions you might ask when interpreting the evidence include: Is the study site degraded? Where and when were fragments introduced? Was there any intervention to improve conditions before planting? What were the environmental conditions over the duration of the study?

The scope of this action does not include planting nurse plants; planting submerged or floating plants; planting to restore bogs, fens, fen meadows or peat swamp forests (see Taylor et al. 2018); or planting facultative wetland plants in upland sites. In contrast, the scope does include planting non-native species to conserve marshes or swamps – whilst acknowledging that this is often considered ethically unacceptable due to the risk of invasion (e.g. Ren et al. 2009).

^{Brown S.C. & Bedford B.L. (1997) Restoration of wetland vegetation with transplanted wetland soil: an experimental study. Wetlands, 17, 424–437.}

^{Laegdsgaard P. (2002) Recovery of small denuded patches of the dominant NSW coastal saltmarsh species (Sporobolus virginicus and Sarcocornia quinqueflora) and implications for restoration using donor sites. Ecological Management & Restoration, 3, 202–206.}

^{Ren H., Lu H., Shen W., Huang C., Guo Q., Li Z. & Jian S. (2009) Sonneratia apetala Buch.Ham in the mangrove ecosystems of China: an invasive species or restoration species? Ecological Engineering, 35, 1243–1248.}

^{Taylor N.G., Grillas P. & Sutherland W.J. (2018) Peatland Conservation: Global Evidence for the Effects of Interventions to Conserve Peatland Vegetation. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge.}

Study locations

Key messages

One study evaluated the effects, on vegetation, of introducing tree/shrub fragments to freshwater wetlands. The study was in the USA.

VEGETATION COMMUNITY

VEGETATION ABUNDANCE

VEGETATION STRUCTURE

OTHER

Survival (1 study): One study in a floodplain swamp clearing in the USA reported 12% overall survival of planted unrooted tree cuttings over two years. For two of four species, no monitored seedlings survived.

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

A study in 2007–2009 in a floodplain swamp restoration site in Wisconsin, USA (Thomsen et al. 2012) reported 12% survival of planted tree cuttings over two years. All surviving individuals were willows Salix spp. No cottonwood Populus deltoides or red osier dogwood Cornus stolonifera cuttings survived at monitored points – although some surviving cottonwood cuttings were noted elsewhere in the site (not quantified). Methods: Fresh (<2-week-old), unrooted tree cuttings were planted into 16 plots in a floodplain swamp restoration site (a clearing created by a storm). Cottonwood cuttings were planted in May 2007. Black willow Salix nigra, sandbar willow Salix exigua and dogwood cuttings were planted in April 2008. All plots had been cleared of invasive reed canarygrass Phalaris arundinacea and disked in November 2006. Herbicide was then applied regularly through to November 2008). Survival was monitored for 28 cuttings situated at survey points.
Study and other actions tested
Referenced paper
Thomsen M., Brownell K., Groshek M. & Kirsch E. (2012) Control of reed canarygrass promotes wetland herb and tree seedling establishment in an Upper Mississippi River floodplain forest. Wetlands, 32, 543-555.

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

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Marsh and Swamp Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Directly plant non-woody plants: brackish/saline wetlands Action Link	Beneficial	30	Synopsis Link
Introduce fragments of trees/shrubs: freshwater wetlands Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Transplant or replace wetland soil: brackish/salt marshes Action Link	No evidence found (no assessment)	0	Synopsis Link