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| Titel |
Cross-shore gradients of physical disturbance in mangroves: implications for seedling establishment |
| VerfasserIn |
T. Balke, T. J. Bouma, P. M. J. Herman, E. M. Horstman, C. Sudtongkong, E. L. Webb |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 8 ; Nr. 10, no. 8 (2013-08-13), S.5411-5419 |
| Datensatznummer |
250085293
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| Publikation (Nr.) |
 copernicus.org/bg-10-5411-2013.pdf |
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| Zusammenfassung |
| Mangroves may grow in an active sedimentary environment and are therefore
closely linked to physical coastal processes. Seedlings colonize dynamic
tidal flats, after which mangroves have the potential to change their
physical environment by attenuating hydrodynamic energy and trapping
sediments. Disturbance from hydrodynamic energy of waves or currents and the
resulting sediment dynamics appear to be a critical bottleneck for seedling
establishment on tidal flats and at the forest fringe. However, knowledge
about the mechanisms at the single plant level and the spatial pattern of
disturbance is limited. By means of a flume study, we demonstrate that a
surface erosion threshold of as little as 1–3 cm depth can lead to failure
of young seedlings. By monitoring accretion/erosion for 8 months along
cross-shore transects in southwest Thailand, we show that, especially on the
bare mudflat, the physical sediment disturbance regularly exceeds the
critical erosion thresholds derived from the flume study. Physical sediment
parameters along the same transects were analysed to deduct patterns of
hydrodynamic energy attenuation. Grain size analysis and erosion/accretion
data showed only limited energy dissipation within the fringing
Avicennia/Sonneratia zone; sediment dynamics only dropped below lethal values for seedlings
within the denser Rhizophora zone. Overall, present results emphasize that (i) seedling
survival is extremely sensitive to physically driven sediment dynamics and
(ii) that such physical disturbances are not only present on the tidal flats but
can penetrate a significant distance into the forest. Spatio-temporal
patterns in sediment dynamics should hence be considered when conducting
restoration of mangrove ecosystems. |
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