Restore/create brackish/saline swamps in areas that will be climatically suitable in the future

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

Effectiveness

70%
Certainty

30%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

It may be wise to prioritize restoration or creation of swamps in areas that will remain – or become more – climatically suitable in the future, rather than areas that are destined to become unsuitable. These areas will provide space for existing vegetation to move into as their current sites become to dry, wet, warm or cold (Oliver et al. 2012).

^{Oliver T.H., Smithers R.J., Bailey S., Walmsley C.A. & Watts K. (2012) A decision framework for considering climate change adaptation in biodiversity conservation planning. Journal of Applied Ecology, 49, 1247–1255.}

Study locations

Key messages

One study evaluated the effects, on vegetation, of restoring or creating brackish/saline swamps in areas expected to be climatically suitable in the future. The study was in South Africa.

VEGETATION COMMUNITY

Overall extent (1 study): One before-and-after study in an estuary in South Africa reported that over 42 years after planting mangrove trees just beyond their current range, the area of mangrove forests increased.

VEGETATION ABUNDANCE

VEGETATION STRUCTURE

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 before-and-after study in 1969–2011 in an estuary in South Africa (Hoppe-Speer et al. 2015) reported that over 42 years after planting mangrove trees just outside their current range, the area of mangrove vegetation increased. Before planting, there were no mangroves present in the estuary. In the year after planting (1970), mangrove forests could not be identified on aerial photographs. Forty-two years after planting (2011), mangrove forests had established and covered 1.6 ha. Although mangroves encroached into and replaced existing salt marshes, the area of salt marsh in the estuary actually increased slightly over time (1970: 2.9 ha; 2011: 3.1 ha). Salt marshes developed on newly deposited sediment. Methods: In 1969, twenty-five grey mangrove Avicennia marina trees (age unclear) were planted into salt marsh in the Nahoon Estuary. This site is 60 km south of naturally occurring mangrove forests in South Africa. “A few” mangrove trees of other species were planted “a few” years later. The area of mangrove forest and salt marsh in the estuary was determined from aerial photographs (taken 1970–2004), satellite images (taken 2004–2010) and field surveys (2011).
Study and other actions tested
Referenced paper
Hoppe-Speer S.C., Adams J.B. & Rajkaran A. (2015) Mangrove expansion and population structure at a planted site, East London, South Africa. Southern Forests: a journal of Forest Science, 77, 131-139.

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

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Build barriers to protect littoral freshwater swamps from rising water levels and severe weather Action Link	No evidence found (no assessment)	Synopsis Link
Restore/create freshwater marshes in areas that will be climatically suitable in the future Action Link	No evidence found (no assessment)	Synopsis Link
Add water to marshes or swamps to compensate for drought Action Link	No evidence found (no assessment)	Synopsis Link