From Salt to C; carbon sequestration through ecological restoration at the Dry Creek Salt Field Sabine Dittmann, Luke Mosley, Kieren Beaumont, Beverley Clarke, Erick Bestland, Huade Guan, Harpinder Sandhu, Michelle Clanahan, Ryan Baring, Jason Quinn, Russell Seaman, Paul Sutton, Sophie Min Thomson, Robert Costanza, Gabriel Shepherd, Molly Whalen, James Stangoulis, Petra Marschner, Murray Townsend Goyder Institute for Water Research Technical Report Series No. xx/18 www.goyderinstitute.org Goyder Institute for Water Research Technical Report Series ISSN: 1839-2725 The Goyder Institute for Water Research is a partnership between the South Australian Government through the Department for Environment and Water, CSIRO, Flinders University, the University of Adelaide, the University of South Australia and the International Centre of Excellence in Water Resource Management. The Institute enhances the South Australian Government’s capacity to develop and deliver science-based policy solutions in water management. It brings together the best scientists and researchers across Australia to provide expert and independent scientific advice to inform good government water policy and identify future threats and opportunities to water security. Enquires should be addressed to: Goyder Institute for Water Research Level 4, 33 King William Street Adelaide, SA 5000 tel: 08 8236 5200 e-mail: [email protected] Citation Dittmann, S., Mosley, L., Beaumont, K., Clarke, B., Bestland, E., Guan, H., Sandhu, H., Clanahan, M., Baring, R., Quinn, J., Seaman, R., Sutton, P., Min Thomson, S., Costanza, R., Shepherd, G., Whalen, M., Stangoulis, J., Marschner, P., Townsend, M. (2019) From Salt to C; carbon sequestration through ecological restoration at the Dry Creek Salt Field. Goyder Institute for Water Research Technical Report Series No. xx/18. © Crown in right of the State of South Australia, Department for Environment and Water. Disclaimer Flinders University, the University of Adelaide, University of South Australia, and the Department of Environment and Water, as the project partners, advise that the information contained in this publication comprises general statements based on scientific research and does not warrant or represent the completeness of any information or material in this publication. The project partners do not warrant or make any representation regarding the use, or results of the use, of the information contained herein about to its correctness, accuracy, reliability, currency or otherwise and expressly disclaim all liability or responsibility to any person using the information or advice. Information contained in this document is, to the knowledge of the project partners, correct at the time of writing. Contents Executive summary....................................................................................................................................... vi Acknowledgments ...................................................................................................................................... viii 1 Introduction .................................................................................................................................... 1 1.1 General aim and objectives of the project ........................................................................... 1 1.2 Research approach ............................................................................................................... 2 1.3 Significance of the project .................................................................................................... 3 2 Tidal re-connection trial .................................................................................................................. 4 2.1 Re-connection trial - context and realisation ....................................................................... 4 2.2 Trial pond developments ...................................................................................................... 6 2.3 Study sites and stratification ................................................................................................ 6 3 Carbon dynamics and sequestration ............................................................................................. 10 3.1 Carbon stocks and dynamics in sediments ......................................................................... 10 3.2 Sediment elevation changes and accumulation rates ........................................................ 14 3.3 Long term sedimentation and carbon sequestration rates ................................................ 15 3.4 Greenhouse gas emissions .................................................................................................. 17 3.5 Carbon stocks and sequestration in biomass ..................................................................... 19 3.6 Summary and discussion of carbon dynamics following tidal re-connection .................... 23 4 Revegetation of trial salt pond ...................................................................................................... 25 4.1 Vegetation surveys inside and outside of pond.................................................................. 25 4.2 Seed dynamics experiments ............................................................................................... 27 4.3 Revegetation inside trial pond and plant cover .................................................................. 34 4.4 Summary and discussion of revegetation investigations ................................................... 37 5 Carbon accounting and registration.............................................................................................. 39 5.1 Blue Carbon offset in the Australian and international context ......................................... 39 5.2 Assessment of alternative ERF methods for mangrove trees............................................. 40 5.3 Suitability of tidal re-connection project activity for the ERF ............................................. 41 5.4 Summary of issues and outlook for Blue Carbon offset mechanisms ................................ 47 6 Co-benefit analyses and up-scaling ............................................................................................... 48 6.1 Co-benefits and other ecosystem services ......................................................................... 48 6.2 Social and cultural values- assessing the cultural ecosystem services of the coastal wetlands between Torrens Island and Thompson Beach ............................................................................. 56 6.3 Spatial and temporal up-scaling of carbon offset opportunities from tidal re-connection of salt ponds ...................................................................................................................................... 59 6.4 Summary and discussion of Blue Carbon and co-benefits from tidal re-connection ......... 65 7 Translation of outcomes ............................................................................................................... 66 References .................................................................................................................................................. 67 Appendix A –Carbon pool data ................................................................................................................... 75 Appendix B – Revegetation ........................................................................................................................ 81 Appendix C –Carbon offset registration ..................................................................................................... 85 Appendix D – Ecosystem service values, social and Cultural Values study figures .................................... 87 From Salt to C; carbon sequestration through ecological restoration at the Dry Creek Salt Field | i Figures Figure 1. Conceptual diagram of Blue Carbon sequestration in coastal ecosystems. .................................. 1 Figure 2. Conceptual diagram of processes enabling Blue Carbon benefits through tidal re-connection of a salt pond. ................................................................................................................................................... 3 Figure 3. Location of the Dry Creek salt field north of Adelaide, South Australia, where solar evaporation ponds extend for ca. 30 km along the Gulf St Vincent coastline from Middle Beach in the north to Port Adelaide in the south. The trial pond, XB8A, is encircled in red and shown in an aerial photo after re- connection (photo DEW). ............................................................................................................................. 4 Figure 4. Historic opening ceremony of the Dry Creek salt field on 20 July 1937 at the once No 1 pumping station, and celebration of tidal re-connection at the same location on 28 July 2017. Photos provided by Peter Bell and Luke Mosley. ......................................................................................................................... 5 Figure 5. Tidal gate infrastructure showing the controllable gates (left) and the polyethylene pipes connecting the trial pond to pumping creek and mangroves in Barker Inlet (right). Photos L. Mosley and S. Dittmann. ...................................................................................................................................................... 5 Figure 6. Photo sequence of the trial pond