Coastal Zones

Biography

Biography: Dr AnneMarie Clements

Abstract

The Magenta Shores golf and tourist development fronts 2.3 km stretch of wind-swept, storm exposed Tuggerah Beach on Australia's east coast. The expected storm bite on this beach during a 1 in 100 year storm event is up to 300 m3 of sand per linear metre of beach, based in the 1974 storm event. The sand dunes were environmentally degraded by former sand-mining, monoculture of Chrysanthemoides monilifera and use as a landfill site. The project aimed to increase the natural defence against storm waves and wind erosion. This was achieved by re-establishing the natural ecosystems associated with the parallel beach ridge landform, typical of a stable coastal Quaternary sand system. Dune slopes were stripped and re-contoured, natural sand trapping mechanisms placed on crests and onshore winds transported the sand to form foredune crests. From the 12 month trials on the re-constructed dunes, the most efficient method of re-establishing foredune Spinifex sericeus dominated vegetation was the burial of ripe Spinifex seed head in the moist sand layer. This achieved primary colonisation and development of a soil fungal hyphae network prior to introduction of secondary colonising species. Germination of Spinifex depended on its ripeness. Ripe seed coincides with bird swarms on the beach harvesting ripe seed in late December. Monitoring stakes were used as roosts by birds, promoting re-introduction of native plant species requiring germination by digestive tract stimulation. Bush regeneration reduced competition from weeds, allowing native vegetation cover to succeed. The success was achieved by mimicking the natural processes and was measured by cumulation of sand volume in the dunes and the ability to withstand the summer storms. The reconstructed dunes now provide enhanced protection from sand movement and storm bite for built assets and natural ecosystems.