Oral Presentation AFSS/NZFSS Joint Conference 2019

Sink or swim? Coastal freshwater wetland vegetation response to rising sea level (#52)

Rebekah Grieger 1 2 , Samantha Capon 1 2 , Wade Hadwen 1 2 3
  1. Australian Rivers Institute, Griffith University, Nathan, QLD, Australia
  2. School of Environment and Science, Griffith University, Nathan, QLD, Australia
  3. Griffith Climate Change Response Program, Griffith University, Gold Coast, QLD, Australia

Coastal freshwater wetlands (CFWs) are highly vulnerable to climate change and the alteration of hydrology and salinity that is predicted with sea level rise (SLR). Investigating the response and resilience of wetland vegetation to predicted changes is important for understanding the threat that climate change poses and to help predict the potential impacts on wetland systems. Through an in-situ manipulation of flooding and salinity regimes at a restored CFW we investigated the responses of major wetland vegetation communities to simulated SLR. Repeat surveying of vegetation composition, structure and, condition was conducted in permanent plots established in Casuarina swamp, Melaleuca swamp, Salt Pan, and Riparian zone vegetation communities, to observe change over time. Groundcover species richness decreased in Salt Pan, Casuarina, and Melaleuca sites after 10 months of altered conditions. A decrease in overall vegetation cover was observed in response to altered conditions in Melaleuca and Casuarina sites, did not change in Riparian sites, but increased in one Salt Pan site. Changes in woody vegetation community and structure were not observed in this the short time period of this study, however woody recruitment and herbaceous regeneration were reduced. This suggests that vegetation transition first occurs in herbaceous species assemblages while changes in woody vegetation occur over longer timeframes. This study highlights the importance of investigation into the in-situ responses of CFW vegetation communities to understand the likely trajectory of vegetation change in response to altered hydrology and increased salinity, as is predicted with climate change and rising sea levels.