Study

Using mangroves to stabilize coastal historic sites: deployment success versus natural recruitment

  • Published source details Donnelly M., Shaffer M., Connor S., Sacks P. & Walters L. (2017) Using mangroves to stabilize coastal historic sites: deployment success versus natural recruitment. Hydrobiologia, 803, 389-401.

Actions

This study is summarised as evidence for the following.

Action Category

Directly plant non-woody plants: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation

Directly plant trees/shrubs: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation
  1. Directly plant non-woody plants: brackish/saline wetlands

    A before-and-after study in 2011–2016 of an intertidal site in Florida, USA (Donnelly et al. 2017) reported 53% survival of transplanted smooth cordgrass Spartina alterniflora after two years, and increases in cordgrass abundance and height over five years. Before planting, the mid-intertidal zone was sparsely vegetated (<1 cordgrass shoots/m2; 2% cover). Five years after planting smooth cordgrass into this zone, its density had increased to 56 shoots/m2 and its cover had increased to 52%. The average height of planted cordgrass had increased, from 37 cm when planted to 67 cm after five years (statistical significance not assessed). No natural recruitment was observed within the first three years after planting (data not reported after this). Methods: The study took place along a 200 m stretch of shoreline, on the edge of an ancient shell waste dump. In April/May 2011, smooth cordgrass Spartina alterniflora was planted in the mid-intertidal zone (620 nursery-reared plants; 3 plants/m). Mangrove seedlings were planted in the upper intertidal zone and oyster-shell mats were placed in the lower intertidal zone. The study does not distinguish between the effects of these interventions on natural recruitment. Cordgrass in the mid-intertidal zone was surveyed before planting (presumably April 2011) and for five years after (2011–2016).

    (Summarised by: Nigel Taylor)

  2. Directly plant trees/shrubs: brackish/saline wetlands

    A before-and-after study in 2011–2016 of an intertidal site in Florida, USA (Donnelly et al. 2017) reported 62% survival of planted red mangrove Rhizophora mangle seedlings after two years, and increases in red mangrove abundance and height over five years. Before planting, the upper intertidal zone was sparsely vegetated (<1 mangrove stem/m2; 3% cover). Five years after planting red mangroves into this zone, their density had increased to 3.5 stems/m2 and their cover had increased to 81%. Most of this vegetation had been planted: limited natural recruitment (0.2 seedlings/m2) was only observed from the fourth year of the study. The average height of surviving seedlings increased, from 36 cm when planted to 92 cm after five years (statistical significance not assessed). Methods: The study aimed to stabilize a 200 m stretch of shoreline, on the edge of an ancient shell waste dump. In April/May 2011, nursery-reared red mangrove seedlings were planted in the high intertidal zone (450 seedlings; 2 seedlings/m). Smooth cordgrass Spartina alterniflora was planted in the mid-intertidal zone and oyster-shell mats were placed in the lower intertidal zone. The study does not distinguish between the effects of these interventions on non-planted mangroves. Mangrove vegetation in the upper intertidal zone was surveyed before intervention (presumably April 2011) and for five years after (2011–2016).

    (Summarised by: Nigel Taylor)

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