Australian Terrestrial and Coastal Marine (Blue) Carbon Stocks 

The soil in terrestrial and blue carbon ecosystems (BCE; mangroves, tidal marshes, seagrasses) is a significant carbon (C) sink. National assessments of C inventories are needed to protect them and aid nature-based strategies to sequester atmospheric carbon dioxide. We harmonised measurements from Australia's terrestrial and BCE and, using consistent multi-scale spatial machine learning, unravelled the drivers of soil organic carbon (SOC) variation and digitally mapped their stocks. The modelling shows that climate and vegetation are continentally the primary drivers of SOC variation. But the underlying regional drivers are ecosystem type, terrain, clay content, mineralogy, and nutrients. The digital soil maps indicate that in the 0-30 cm soil layer, terrestrial ecosystems hold 27.6 Gt (19.6-39.0 Gt), and BCE 0.35 Gt (0.20-0.62 Gt). Tall open eucalypt and mangrove forests have the largest mean SOC per unit area. Eucalypt woodlands and hummock grassland, which occupy vast areas, store the largest total SOC stock. These ecosystems constitute important regions for conservation, emissions avoidance, and preservation because they also provide additional co-benefits. 

We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging. Authors thank the Australian Government for funding this research via grant ACSRIV000077. We thank all co-authors and their contributions, and the many colleagues who contributed to the collection of soil samples and data used in this research. This work is also supported by the use of (i) Terrestrial Ecosystem Research Network (TERN) infrastructure, which is enabled by the Australian Government’s National Collaborative Research Infrastructure Strategy (NCRIS), and (ii) computational resources in the Pawsey Supercomputing Centre, which is funded by the Australian Government and the Government of Western Australia. 

A fine spatial resolution, spatially explicit dataset on the soil organic carbon stocks (t/ha) in Australia's terrestrial and coastal marine (or blue carbon: mangroves, tidal marshes, seagrasses) ecosystems. The data provides a consistently-derived and up-to-date baseline of Australia's 0-30 cm soil carbon stocks. Can be used by land managers, researchers, and policy-makers. 

The data was produced using a compilation of various regional datasets. They were analysed and harmonised using statistical methods that are described in the publication that describes the research - Walden et al. (2023) in Communications Earth & Environment.