Coevolution of hydraulic, soil and vegetation processes in estuarine wetlands.
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Date
2014-04
Journal Title
Journal ISSN
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Publisher
European Geophysical Union
Abstract
Estuarine wetlands of south eastern Australia, typically display a vegetation
zonation with a sequence mudflats - mangrove forest - saltmarsh plains from the
seaward margin and up the topographic gradient. Estuarine wetlands are among the
most productive ecosystems in the world, providing unique habitats for fish and many
terrestrial species. They also have a carbon sequestration capacity that surpasess
terrestrial forest.
Estuarine wetlands respond to sea-level rise by vertical accretion and horizontal
landward migration, in order to maintain their position in the tidal frame. In
situations in which buffer areas for landward migration are not available, saltmarsh
can be lost due to mangrove encroachment. As a result of mangrove invasion
associated in part with raising estuary water levels and urbanisation, coastal
saltmarsh in parts of south-eastern Australia has been declared an endangered
ecological community.
Predicting estuarine wetlands response to sea-level rise requires modelling the
coevolving dynamics of water flow, soil and vegetation. This paper presents
preliminary results of our recently developed numerical model for wetland dynamics
in wetlands of the Hunter estuary of NSW. The model simulates continuous tidal
inflow into the wetland, and accounts for the effect of varying vegetation types on
flow resistance. Coevolution effects appear as vegetation types are updated based on
their preference to prevailing hydrodynamic conditions. The model also considers
that accretion values vary with vegetation type. Simulations are driven using local
information collected over several years, which includes estuary water levels,
accretion rates, soil carbon content, flow resistance and vegetation preference to
hydraulic conditions. Model results predict further saltmarsh loss under current
conditions of moderate increase of estuary water levels.
Description
Keywords
Estuarine wetlands, Coevolution hydraulic soil and vegetation, Hunter estuary