MEPS 440:1-9 (2011)  -  DOI: https://doi.org/10.3354/meps09364

FEATURE ARTICLE
Windows of opportunity: thresholds to mangrove seedling establishment on tidal flats

Thorsten Balke1,*, Tjeerd J. Bouma1,2, Erik M. Horstman3, Edward L. Webb4, Paul L. A. Erftemeijer1,5, Peter M. J. Herman2

1Deltares, PO Box 177, 2600 MH Delft, The Netherlands
2Centre for Estuarine and Marine Ecology, Netherlands Institute of Ecology (NIOO-KNAW), 4400 AC Yerseke, The Netherlands
3Department of Water Engineering & Management, University of Twente, 7500 AE Enschede, The Netherlands
4Department of Biological Sciences, National University of Singapore, Singapore 117543
5Present address: Sinclair Knight Merz (SKM), PO Box H615, Perth, Western Australia 6001, Australia

ABSTRACT: Physical processes limiting colonization of bare tidal flats by pioneer mangrove species have commonly been described but not yet quantified. Understanding thresholds to early seedling establishment is critical for successful restoration and management of mangrove forests. We determined how seedling establishment of Avicennia alba Bl. is affected by the combination of increasing hydrodynamic forces and sediment dynamics. As the buoyant propagules of A. alba are dispersed by water, early establishment on bare tidal flats requires propagules to quickly anchor to stay in place. Flume studies and field observations showed that 3 thresholds have to be passed until the seedling is successfully established: (1) stranded propagules need an inundation-free period to rapidly develop roots that are long enough to withstand displacement by flooding, (2) roots need to become long enough to withstand seedling dislodgement by hydrodynamic forces from waves and currents, with the required root length being proportional to the force that needs to be resisted, (3) even longer roots are needed to survive high energy events that cause sheet erosion and can thereby induce seedling dislodgement. This sequence of thresholds implies that establishment of the pioneer mangrove species A. alba requires a suitable window of opportunity to pass all thresholds and underlines the importance of rapid root expansion as a crucial pioneer trait for the species.


KEY WORDS: Avicennia · Colonization · Flume · Pioneer · Mangrove restoration · Seedling establishment · Succession · Threshold


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Cite this article as: Balke T, Bouma TJ, Horstman EM, Webb EL, Erftemeijer PLA, Herman PMJ (2011) Windows of opportunity: thresholds to mangrove seedling establishment on tidal flats. Mar Ecol Prog Ser 440:1-9. https://doi.org/10.3354/meps09364

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