Experimental and field regeneration of coastal saltmarsh within Sydney Olympic Park

During realignment of the former stormwater drain in late 1999, coastal saltmarsh beds were constructed along the upper portion of Haslams Creek (the Haslams Creek Flats precinct) within Sydney Olympic Park. While the northern flats of the Creek have had reasonable regeneration of coastal saltmarsh, regeneration on the southern flats was not as successful. Several trials had been undertaken to regenerate coastal saltmarsh on the southern flats. The attempt that yielded the best outcome was through replacement of topsoil followed by vegetation planting. This was considered an expensive approach. Prior to employing this approach in the remaining areas, an alternative approach was trialled in 2006-07. These trials yielded even better outcomes, and did not involve replacing the topsoil, but rather amelioration of the existing topsoil/sediment through incorporation of mangrove mulch. Saltmarsh plants naturally seeded on the flats and significantly higher numbers of seedlings self-germinated and continued to grow in mangrove-mulch incorporated treatments. To validate this approach a field regeneration attempt was made in 2007 in one section of the flats and successful results have been achieved. The results were so encouraging that the same approach was applied in 2008 to allow self regeneration in the remaining parts of the flats and the results are equally promising. The experimental trial provided valuable additional information. Based on the findings some useful management recommendations are suggested.