Restoring the soils of Nauru Plants as tools for Ecological Recovery by Alexander Feary A thesis in partial fulfilment for a degree in Ecological Restoration at Victoria University of Wellington, New Zealand. Abstract The restoration of Nauru’s mined areas is fundamental to the future wellbeing of the people and ecosystems of Nauru. Extensive open cast phosphate mining on Nauru over the last 100 years has led to soil losses and landscape degradation to the extent that over 70% of this South-Western Pacific island state is now uninhabitable and almost all productive land has been lost. Significant landscape degradation has occurred and as a consequence the soils that remain are insufficient in volume and quality to achieve the Government’s restoration goals which support the long-term development of Nauru and the well-being of its people. The aim of this research is to evaluate aspects of cover-crop use as a means for soil restoration in Nauru. This research evaluates biomass production, phytoremediation potential, and germination success for a range of species in Nauruan soils. Field trials exploring biomass production and cadmium phytoextraction were performed, as was an experiment assessing the effects of cadmium on germination success. It was found that, in the circumstances assessed, biomass productivity was significantly determined by species, mulch use, soil type, and to a small degree – cadmium. Phytoextraction was significantly determined by tissue type. Germination success was not determined by soil cadmium, but soil type was a significant factor. i ii Acknowledgements I have been extremely fortunate to have had the support of a large number of generous and brilliant people while working on this report. My supervisors Dr Murray Williams and Dr Sean Weaver have provided invaluable support. Xavier Barker and Alamanda Lauti of the Nauru branch of the University of the South Pacific provided sponsorship, resources, and accommodated me in their homes. For this I am deeply indebted to them, and to their families. George Fraser, Australian Consul-General and Special Representative to Nauru gave me time and personal introductions. The following Nauru government officials met with me at various times and granted me the benefit of their insight: Minister of Education Rus Kun; Minister of Foreign Affairs and Trade Dr Kieran Keke; Minister of Commerce, Industry and Enterprise (CIE), Minister for Rehabilitation, and Minister for Mining Frederick Pitcher; and Director for Agriculture, CIE, Frankie Ribauw. The following NRC staff members provided information and direction - John Gray – Project Engineer, Lahn Debao – NRC Surveyor, Creedance Halstead – NRC Assistant Project Engineer, Yanjol Issacs – Planning Engineer. The Freemasons and NZAid provided financial support, without which I would have been unable to visit Nauru. Credit must go to the lovely support staff of the School of Biological Sciences at Victoria University, who keep our department together. iii Dr Joel Baker and Dr Marc-Alban Millet provided ICP-MS facilities and technical support for sample analysis. Warmest thanks to those who reviewed and proofed this report- Connie May Nisbett, Elise Ruth Broadbent, and Thomas Brydone Taptiklis. Thom’s parsing was brutal. Your meticulous attention to detail has significantly improved the clarity of my writing. I was extremely fortunate to have worked with the Nursery Staff of the Nauru Rehabilitation Corporation. I would particularly like to thank Harry Duncan Stroggoffadam, Lio Eauwe Agadio, Frangipani Detogia, Timex Dabwido, Jeriel Jeremiah, Gideon Teabuge, Maxwell Kosam, Louisiana Grundler, the Nursery Foreman Noah Telani and Assistant Nursery Foreman Justin Fine Olsson. The time that we spent together has been for me the most memorable part of this thesis. To my friends and family who have listened to me ramble on about Nauru ad absurdum, thank you for your tolerance and kind support. iv Table of Contents Abstract ............................................................................................... i Acknowledgements ......................................................................... iii Table of Contents .............................................................................. v Terms and Abbreviations .................................................................xi Chapter One - Introduction and background to the rehabilitation of the soils of Nauru ...................................................... 1 Introduction ........................................................................................................... 1 Discovery of Phosphate Deposits ..................................................................... 2 Nauru Land Rehabilitation ................................................................................. 4 Experimental planning and design .......................................................... 6 Soil ........................................................................................................................... 7 Climate .................................................................................................................. 9 Freshwater ........................................................................................................... 10 Mandate to rehabilitate ............................................................................... 11 Ecological restoration ................................................................................... 14 Soil restoration ................................................................................................... 17 Ecological relevance ........................................................................................ 17 Nauru soil ecology ............................................................................................. 17 Increasing soil quantity and quality ............................................................... 18 Biomass production ........................................................................................... 22 Phytoremediation of soils ................................................................................. 26 Germination ........................................................................................................ 32 Adaptive management ............................................................................... 32 Research approach and thesis content .............................................. 34 Biomass production in Nauru ........................................................................... 35 Cadmium phytoremediation .......................................................................... 36 v Effects of cadmium on germination success ............................................... 36 References .......................................................................................................... 36 Chapter Two - Biomass production in Nauru: A preliminary field trial ................................................................................................................. 53 Abstract ................................................................................................................ 53 Introduction ........................................................................................................ 53 Aim .......................................................................................................................... 58 Hypotheses ......................................................................................................... 58 Method .................................................................................................................. 58 Variables ............................................................................................................. 59 Complications .................................................................................................... 61 Field plots ............................................................................................................ 62 Sample Preparation and Analysis .................................................................. 66 Results .................................................................................................................... 70 Soil cadmium ...................................................................................................... 70 Biomass productivity ......................................................................................... 72 Biomass productivity of specific soil types .................................................... 75 Discussion ............................................................................................................ 78 Research outcomes .......................................................................................... 78 Research limitations .......................................................................................... 80 Relevance to academic literature ................................................................ 80 Conclusion .......................................................................................................... 81 References .......................................................................................................... 82 Chapter Three - Cadmium phytoaccumulation in Nauruan plants: A preliminary field trial .......................................................... 87 Abstract ...............................................................................................................