HR: 1340h
AN: H53D-1452    [Abstracts]
TI: Surface Elevation, Carbon Sequestration Potential and Rising sea Levels in Estuarine Wetlands
AU: * Rodríguez, J F
EM: jose.rodriguez@newcastle.edu.au
AF: School of Engineering, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia
AU: Howe, A
EM: alice.howe@studentmail.newcastle.edu.au
AF: School of Engineering, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia
AU: Saco, P M
EM: patricia.saco@newcastle.edu.au
AF: School of Engineering, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia
AB: Estuarine wetlands are among the most productive ecosystems on Earth, providing habitat for commercially important fish species and migratory shorebirds, serving as nurseries for many other marine organisms and supporting the productivity of adjacent coastal waters. Typically, these wetlands are driven by tidal hydrodynamics and are net sinks for sediment and soil carbon. Their distribution in the tidal frame depends on a delicate balance between topographic gradient, the rate of vertical soil development, and the rate of sea level change. The complex interactions between hydrodynamics, ecology and soil processes that govern this balance produce positive feedbacks and system self-organization. As complex systems, these wetlands demonstrate resilience under a wide range of conditions but they have been observed to collapse or move to another equilibrium state above certain thresholds. Research at a wetland in the Hunter estuary, southeast Australia has tracked changes in relative sea level and surface elevation in mangrove and saltmarsh wetlands over a five year period (2002- 2006) and soil carbon over a two year period (2005-2006). Mangrove surface elevation was strongly correlated with relative sea level (R²=0.715, p=0.004) but there was no correlation between relative sea level and saltmarsh surface elevation (R²=0.093, p=0.424). Soil carbon levels were high in both vegetation types (% loss on ignition of 16.2% and 18.8% for mangrove and saltmarsh soils, respectively) and not significantly different (ANOVA F=1.36, p=0.270). A 16% increase in soil carbon was recorded in each vegetation type over the period 2005-2006. Mean annual sea level rose by 55 mm and net annual precipitation (rainfall minus evaporation) fell by 189 mm over the same period. The ability of mangrove to respond rapidly to changes in relative sea level and the indicative positive trend between soil carbon and relative sea level suggest that this wetland type is both resilient to future sea level rise and has the potential to sequester carbon. Saltmarsh exhibited a similar potential for carbon sequestration, but low resilience to rising sea level, particularly in areas with steep or urbanised landward topography. Incorporation of these findings into general models of wetland hydrodynamics will inform strategies for adaptive management of estuarine wetlands in response to future climate change.
DE: 1807 Climate impacts
DE: 1851 Plant ecology (0476)
DE: 1890 Wetlands (0497)
SC: Hydrology [H]
MN: 2007 Fall Meeting