Introduce nurse plants to aid focal trees/shrubs: brackish/saline wetlands

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

Effectiveness

30%
Certainty

20%
Harms

5%

Calculating overall effectiveness category

Background information and definitions

Nurse plants, also known as companion plants or pioneer plants, can be planted alongside focal plants to help the focal plants establish (Padilla & Pugnaire 2006). Nurse plants may benefit focal plants in variety of ways, including: trapping and stabilizing sediments, trapping propagules, mitigating harsh environmental conditions (e.g. temperature fluctuations and strong sunlight), attracting pollinators, deflecting herbivory away from focal species, and/or limiting weed establishment.

Caution: Nurse plant species must be chosen carefully. Species that spread easily or are very strong competitors can cause more harm than good. For example, the non-native mangrove apple Sonneratia apetala has been used to restore Chinese mangroves, but has spread into neighbouring forests (Ren et al. 2009). Use of non-native nurse plants may not always be ethically acceptable.

To be summarized as evidence for this action, studies must have (a) deliberately introduced nurse plants before planting target marsh or swamp vegetation, and (b) reported the effects of the nurse plants on other vegetation, not just the survival or growth of the nurse plants. Studies must have explicitly planted vegetation for its nursing effect. Studies are not summarized as evidence here if they planted target vegetation into existing nurse vegetation (e.g. Egerova et al. 2003; McKee et al. 2007), or examined spontaneous colonization amongst planted nurse vegetation.

Related actions: Introduce nurse plants without introducing target marsh or swamp vegetation.

^{Egerova J., Proffitt C.E. & Travis S.E. (2003) Facilitation of survival and growth of Baccharis halimifolia L. by Spartina alterniflora Loisel. in a created Louisiana salt marsh. Wetlands, 23, 250–256.}

^{McKee K.L., Rooth J.E. & Feller I.C. (2007) Mangrove recruitment after forest disturbance is facilitated by herbaceous species in the Caribbean. Ecological Applications, 17, 1678–1693.}

^{Padilla F.M. & Pugnaire F.I. (2006) The role of nurse plants in the restoration of degraded environments. Frontiers in Ecology and the Environment, 4, 196–202.}

^{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.}

Study locations

Key messages

One study evaluated the effects, on vegetation, of introducing nurse plants to brackish/saline wetlands planted with trees/shrubs. The study was in the USA.

VEGETATION COMMUNITY

VEGETATION ABUNDANCE

VEGETATION STRUCTURE

OTHER

Survival (1 study): One replicated, controlled study on a mudflat in the USA found that planting black mangrove Avicennia germinans seedlings into created stands of saltwort Batis maritima did not clearly affect their survival, over seven weeks, compared to planting into bare mud.

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 replicated, controlled study in 2005 on a mudflat in Florida, USA (Milbrandt & Tinsley 2006) reported that planting saltwort Batis maritima as a nurse plant had no clear effect on survival of planted black mangrove Avicennia germinans. Statistical significance was not assessed. After seven weeks, 6% of black mangrove seedlings planted into newly created saltwort patches were alive, compared to 11% of black mangrove seedlings planted into a bare mudflat. This followed fluctuations over the previous six weeks, when mangrove survival was sometimes higher in saltwort stands than on the bare mudflat (two weeks), sometimes lower (three weeks) and sometimes equal (one week). Methods: In June 2005, saltwort seedlings were planted into a mudflat, where a former mangrove forest had died off, to create patches of saltwort. The study does not clearly report patch number, density or size. Within five days, 18 nursery-reared black mangrove seedlings were planted into the saltwort and 18 were planted into the adjacent bare mudflat. Survival was measured over seven weeks.
Study and other actions tested
Referenced paper
Milbrandt E.C. & Tinsley M.N. (2006) The role of saltwort (Batis maritima L.) in regeneration of degraded mangrove forests. Hydrobiologia, 568, 369-377.

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

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Add inorganic fertilizer before/after planting non-woody plants: freshwater wetlands Action Link	Likely to be beneficial	4	Synopsis Link
Add below-ground organic matter before/after planting trees/shrubs: freshwater wetlands Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Introduce nurse plants to aid focal non-woody plants: freshwater wetlands Action Link	Unknown effectiveness (limited evidence)	2	Synopsis Link