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| Titel |
Rhizosphere dynamics of two riparian plant species from the water fluctuation zone of Three Gorges Reservoir, P.R. China - pH, oxygen and LMWOA monitoring during short flooding events |
| VerfasserIn |
Christina M. Schreiber, Ulrich Schurr, Bo Zeng, Agnes Höltkemeier, Arnd J. Kuhn |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040768
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| Zusammenfassung |
| Since the construction of the Three Gorges Dam at the Yangtze River in China, the
reservoir management created a new 30m water fluctuation zone 45-75m above
the original water level. Only species well adapted to long-time flooding (up to
several months) will be able to vegetate the river banks and replace the original
vegetation.
To investigate how common species of the riverbanks cope with submergence, Alternanthera
philoxeroides Mart. and Arundinella anomala Steud., two flooding resistant riparian species,
have been examined in a rhizotron environment. Short-time (2 days waterlogging, 2 days
flooding, 2 days recovery) flooding cycles in the original substrate and long time (14 days
waterlogging, flooding, recovery) flooding cycles, in original substrate and sterile
glass bead substrate, have been simulated in floodable two-way access rhizotrons.
Oxygen- and pH-sensitive foils (planar optodes, PreSens) automatically monitored
root reaction in a confined space (2cm2 each) on the backside of the rhizotron,
while soil solution samples were taken 2 times a day from the other side of the
rhizotron at the corresponding area through filter and steel capillaries. The samples
were analyzed by capillary electrophoresis for low molecular weight organic acids
(LMWOA, i.e. oxalic, formic, succinic, malic, acetic, glyoxylic, lactic and citric
acid).
Results show diurnal rhythms of rhizospheric acidification for both species in high resolution,
combined with oxygen entry into the root surrounding during waterlogged state. Flooding
caused stronger acidification in the rhizosphere, that were however not accompanied by
increased occurrence of LMWOA except for acetic and glyoxylic acid. First results from
longer flooding periods show stable diurnal rhythms during waterlogging, but no strongly
increased activity during the flooding event.
Performance of the two species is not hampered by being waterlogged, and they follow a
silencing strategy during a longer phase of anoxia without strong root turnover
activity. A. anomala with its strong root system and ability to survive flooding is
considered suitable for re-vegetating the riverbanks to help prevent further erosion, while
A. philoxeroides, which discards its weaker roots during prolonged flooding and produces
new roots afterwards, does not contribute much to soil stabilization. |
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