Monitoring of CO2 Fluxes from Differing Vegetation Communities using the Eddy Covariance Approach

Coastal vegetated ecosystems, including wetlands and saltmarsh, have been widely recognised as providing a range of environmental, social, and cultural benefits. They have the ability to store more carbon than nearly any other vegetated system, making them the target of increasing study due to the potential play a role in the mitigation of some effects of climate change. Wetland vegetation have been recognised for having a high carbon sequestration rate. But the carbon cycling dynamics between vegetation types in Australian saltmarshes is lesser known. Framed within a small wetland on the New South Wales South Coast, this research project aimed to monitor greenhouse gas fluxes and how environmental variables influence these fluxes. Monitoring was carried out through the erection of two eddy covariance flux towers which measure fluxes of CO2 from the wetland surface. Soil and water sampling was conducted to analyse salinity, bulk density, carbon content and pH, while measuring biomass across vegetation communities. Using these measurements, expected differences in fluxes between two vegetation communities with differing vegetation structures and compositions were identified. These two communities were differentiated by their dominant species, one by Sarcocornia quinqueflora, and the other by Juncus kraussii. The comparison of the two communities allowed for potential drivers of CO2 fluxes to be identified, based on the sampled environmental variables, and their location within the wider wetland itself. Fluxes of CO2 differed between the two monitored vegetation communities. This difference occurred when comparing both the 24-hour average of half-hourly flux data and the daytime-only half-hourly average flux data. The Juncus-dominated community had a stronger negative CO2 flux than the Sarcocornia-dominated community, indicating a stronger ability to drawn down more carbon out of the atmosphere (-0.078 ± 0.013 and -0.029 ± 0.0063 mg CO2 m-2 s-1 respectively). The poss