Predicting carbon sequestration capacity of Australian coastal wetlands under sea level rise and human pressures.
Abstract
Sea level rise has the potential to profoundly affect the vegetation distribution of coastal wetlands, threatening their important ecosystem services including carbon sequestration. The response of wetland vegetation communities depends on a range of factors including the rate of sea level rise and the rate of surface elevation change due to wetland eco-geomorphic accretion. If wetland accretion is unable to match sea level rise and relatively steep landward topography precludes their landward transgression, estuarine wetlands may be completely submerged, losing all their ecological value and potentially also their carbon stores. As carbon sequestration rates of subtidal substrates are lower than those of coastal wetlands, conversion of wetlands to these substrates would reduce carbon sequestration capacity. If conversion was associated with soil oxidation or erosion, there is potential for former coastal wetland carbon stores to be released. Landward expansion of coastal wetlands, on the other hand, provides a potential mechanism for increased carbon sequestration in response to sea-level rise.
In addition to sea-level rise, human pressures also affect coastal wetlands and their carbon sequestration capacity. In SE Australia these wetlands are heavily managed and typically present infrastructure including flow control devices. How these flow control structures are operated respond to different management strategies that in some cases include ecological conservation of specific vegetation communities. Sea-level rise will change hydraulic conditions in wetlands and may result in flow control structures and strategies becoming obsolete or even counterproductive. In order to predict the evolution of wetland vegetation distribution and its future carbon sequestration potential during sea-level rise, we have developed an eco-geomorphic model that can include the effects of flow control strategies. The model predicts changes in vegetation communities' distribution, vegetation biomass, soil accretion and soil carbon, which are combined to estimate carbon sequestration potential of coastal wetlands under different management strategies.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B43H2545R
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0490 Trace gases;
- BIOGEOSCIENCES;
- 0497 Wetlands;
- BIOGEOSCIENCES