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| Titel |
Bio-geomorphic feedback causes alternative stable landscape states: insights from coastal marshes and tidal flats |
| VerfasserIn |
Stijn Temmerman, Chen Wang |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250095914
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| Publikation (Nr.) |
 EGU/EGU2014-11389.pdf |
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| Zusammenfassung |
| Many bio-geomorphic systems, such as hill slopes, river floodplains, tidal floodplains and
dune areas, seem to be vulnerable to shifts between alternative bare and vegetated landscape
states, and these shifts seem to be driven by bio-geomorphic feedbacks. Here we search for
empirical evidence for alternative stable state behavior in intertidal flats and marshes, where
bio-geomorphic interactions are known to be intense.
Large-scale transitions have been reported worldwide between high-elevation vegetated
marshes and low-elevation bare flats in intertidal zones of deltas, estuaries, and coastal
embayments. It is of significant importance to understand and predict such transitions,
because vegetated marshes provide significant services to coastal societies. Previous
modeling studies suggest that the ecological theory of catastrophic shifts between alternative
stable ecosystem states potentially explains the transition between bare flats and vegetated
marshes. However, up to now only few empirical evidence exists. In our study, the hypothesis
is empirically tested that vegetated marshes and bare tidal flats can be considered as
alternative stable landscape states with rapid shifts between them. We studied historical
records (1930s – 2000s) of intertidal elevation surveys and aerial pictures from the
Westerschelde estuary (SW Netherlands). Our results demonstrated the existence of: (1)
bimodality in the intertidal elevation distribution, i.e., the presence of two peaks in the
elevation frequency distribution corresponding to a completely bare state and a
densely vegetated state; (2) the relatively rapid transition in elevation when intertidal
flats evolve from bare to vegetated states, with sedimentation rates that are 2 to 8
times faster than during the stable states; (3) a threshold elevation above which the
shift from bare to vegetated state has a high chance to occur. Our observations
demonstrate the abrupt non-linear shift between low-elevation bare flats and high-lying
vegetated marshes, suggesting that bare and vegetated states are potentially alternative
stable landscape states with the occurrence of relatively abrupt shifts between them. |
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