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Saintilan N, Sun Y (2022) Integration, analysis and publication of the Australian Surface Elevation Table-Marker Horizon Dataset. Report to the National Environmental Science Program. Macquarie University
Tidal wetlands provide significant ecosystem services across the Australian coastal zone. The capacity of tidal wetlands to adjust vertically to sea-level rise has been the subject of extensive research, and a body of theory has developed concerning feedbacks between sea-level rise and the rate of sedimentation and new root production in wetlands. Allochthonous sediment inputs and autochthonous organic production increase wetland surface elevation, moderating the impacts of sea-level rise. The extent to which these processes operate globally, and between wetland types, is a subject of considerable research interest. The Surface Elevation Table (SET) network has been developed over 30 years to answer these questions. The SET is a benchmark rod installed in wetlands against which wetland elevation change can be measured. Periodic readings of the SET allow the trajectory of wetland elevation gain and sediment accretion to be measured over time. The difference between sediment accretion and elevation gain is a measure of subsidence, the auto-compaction of the upper marsh surface under the weight of sediment and water.
This project collated the Australian SET data and provided an initial analysis of accretion and surface elevation trends. It identified and collated data for 268 SETs across four states and the Northern Territory. The network is clustered near major populations centres of Brisbane, Sydney, Newcastle, Wollongong, Melbourne, Perth and Darwin. SET installations are mostly in mangrove forests, but also cover a range of tidal marsh and tidal forest ecosystems. Associations between accretion and subsidence are explored in different settings, and recommendations are made for development of the Australian SET network.