Geomorphology and habitat dynamics
Since the early work of Lugo and Snedaker (1974), geomorphology has been used to organise our understanding of the interactions between coastal wetlands and their habitats. Mangroves and saltmarshes respond to hydrological and geomorphic conditions in consistent ways (Thorn et al. 1967; Woodroffe 1983), such that the relationships between hydrological and geomorphic change can be used as a template to predict changing distributions of mangrove and saltmarsh. With the exception of Tasmania, where mangroves are absent, saltmarshes in Australia are restricted to the upper intertidal environment, generally between the elevation of the mean high tide, and the mean spring tide. The distribution of these environments within an estuary or embayment is controlled by patterns of riverine and marine sedimentation, shaped by the major hydrological drivers of river discharge and tidal propagation. The position of intertidal flats within an estuary will also exert profound influences on water salinity, and provide a major control over the suite of saltmarsh species present.