Current and future carbon stocks in coastal wetlands within the Great Barrier Reef catchments
Journal Publication ResearchOnline@JCUAbstract
Australia’s Great Barrier Reef (GBR) catchments include some of the world’s most intact coastal wetlands comprising diverse mangrove, seagrass and tidal marsh ecosystems. Although these ecosystems are highly efficient at storing carbon in marine sediments, their soil organic carbon (SOC) stocks and the potential changes resulting from climate impacts including sea level rise are not well understood. For the first time, we estimated SOC stocks and their drivers within the range of coastal wetlands of GBR catchments using boosted regression trees (i.e., a machine learning approach and ensemble method for modelling the relationship between response and explanatory variables) and identified the potential changes in future stocks due to sea level rise. We found levels of SOC stocks of mangrove and seagrass meadows have different drivers, with climatic variables such as temperature, rainfall, and solar radiation, showing significant contributions in accounting for variation in SOC stocks in mangroves. In contrast, soil type accounted for most of the variability in seagrass meadows. Total SOC stocks in the GBR catchments, including mangroves, seagrass meadows and tidal marshes, is approximately 137 Tg C. Total stocks in the GBR catchments, including mangroves, seagrass meadows and tidal marshes, is approximately 137 Tg C. The SOC stored within coastal wetlands in the GBR catchments represent 9-13% of Australia’s total SOC stocks while encompassing only 4-6% of the total extent of Australian coastal wetlands. In a global context, this could represent 0.5-1.4% of global SOC stocks. Our study suggests that landward migration due to projected sea level rise has the potential to enhance SOC stocks with total carbon gains between 0.16-0.46 Tg C and provides an opportunity for future restoration to enhance blue carbon gains.
Journal
Global Change Biology
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Volume
27
ISBN/ISSN
1365-2486
Edition
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Issue
14
Pages Count
15
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Publisher
Blackwell Publishing
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DOI
10.1111/gcb.15642