Lincoln University Digital Thesis Copyright Statement The digital copy of this thesis is protected by the Copyright Act 1994 (New Zealand). This thesis may be consulted by you, provided you comply with the provisions of the Act and the following conditions of use: you will use the copy only for the purposes of research or private study you will recognise the author's right to be identified as the author of the thesis and due acknowledgement will be made to the author where appropriate you will obtain the author's permission before publishing any material from the thesis. Ecological Restoration of Dryland Kānuka Communities in an Irrigated Agricultural Landscape A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University by Rebecca Dollery Lincoln University 2017 Abstract of a thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy. Abstract Ecological Restoration of Dryland Kānuka Communities in an Irrigated Agricultural Landscape by Rebecca Dollery The Canterbury Low Plains ecological district exists as a highly modified, productive landscape containing little of its original indigenous vegetation. The residual native plant communities comprise scattered fragments of dryland shrubland with varying degrees of legal protection. One such area, the Eyrewell Forest, comprised a matrix of small dryland kānuka (Kunzea serotina) communities subsumed within an exotic pine plantation (6,764 ha) and pastoral land, and was described as the largest kānuka shrubland stand on the Canterbury Plains. Since 2010, the plantation has been progressively removed for conversion to precision-irrigated dairy farming. Within this landscape matrix, the current project focused on the establishment of ecological restoration areas and corridors to re-construct, protect and enhance indigenous species and habitats. The community structure and ecology of plant assemblages and associated edaphic conditions within existing remnants were investigated to assist in design, implementation and management of 18 ecological restoration blocks encompassing approximately 150 ha. A particular focus was the importance of moss carpets within natural kānuka-dominant ecosystems. I investigated the responses of the habitat and its plant species to nutrient spillover from adjacent farmland and evaluated restoration techniques suitable for the task. Study of the remnant kānuka habitats revealed that the native vegetation is characterised by low-nutrient soils and the dry climate, supporting assemblages of plants with obvious xerophytic traits. Small-scale disturbance was found to be critical for regeneration of the single canopy species, kānuka, and an understory shrub, Pomaderris amoena. The dominant ground cover moss species, Hypnum cupressiforme, and two woody associates, Leptecophylla juniperina and Carmichaelia australis, regenerated in areas of low disturbance and high canopy cover. Germination trials had some difficulties; P. amoena seeds required heat treatment and naturally followed fires, but L. juniperina could not be germinated artificially. H. cupressiforme exerted significant influence over the functioning of the ecosystem with regards to hydrology, nutrient cycling and biotic interactions. Extremes of soil ii temperature and moisture were mediated by the moss carpet; soil nutrients, particularly mineral nitrogen, were reduced. The moss layer also had species-specific effects on flora but generally decreased germination and establishment of native species. Glasshouse trials showed that K. serotina, P. amoena and Kunzea robusta grew better with soil additions of nitrogen. C. australis and H. cupressiforme responded positively to lime additions, but L. juniperina showed no response. In the field, fertilisation had either negligible or detrimental effects on native species. Increased soil nutrients from organic amendments elicited exotic weed encroachment. Nutrient spillover from farmland was observed at least 30m into remnant kānuka ecosystems and was positively correlated with exotic weeds but negatively related to moss cover. Successful introduction of planted native species required protection from desiccation and competition from weeds. Tree guards successfully and cost-effectively sheltered young plants and moss. Weeds were best controlled by herbicide application and, moderately with moss and pine litter mulch. This research has contributed to the restoration of 150 ha of landscape restoration, generating practical applications for similar projects elsewhere. A major finding is the importance of integrating moss into dryland kānuka restoration projects. Keywords: Ecological restoration, kānuka shrubland, Kunzea serotina, Pomaderris amoena, Hypnum cupressiforme, bryophyte, nutrient spillover, tree guard, glyphosate, direct seeding, fertilser tablet. iii Acknowledgements Firstly, my sincerest thanks goes to the creative, experienced and enthusiastic supervisors who have managed and overseen my PhD, Professor Nick Dickinson and Mike Bowie. Together, these supervisors have imparted their extensive knowledge, given me a great deal or support and motivation, and quite literally moved mountains for me (of compost and sawdust). As a team we would like to thank my sponsor, Ngāi Tahu Farming Ltd., for the opportunity to undertake this research project which has direct implications for the future of indigenous restoration projects within Canterbury and beyond. In particular, we would like to acknowledge the support from Glen Clayton and Andrew Priest, along with his predecessor Andrew Clayton. The knowledge and organisational help from Ben Geisen, Rhys Narbey, Noel Roberts, John Blackadder and their team has been invaluable, ever willing to help out and assist in new experiments to further the restoration project. A thank you also to Nann Berry for keeping us organised and ensuring communication between Lincoln University and all stakeholders. Special thanks to the Mana Whenua Working Party for sharing of knowledge, guidance, advice and much valuable discussion. There has been a whole host of activity constantly occurring in the field from setting up equipment, gathering soil, measuring plants, and moving wheelbarrow after wheelbarrow of sawdust. A prominent assistant in all of this has been Paula Greer. Paula’s dedication, support, knowledge and navigational skills have been indispensable both in the field and back in the laboratory. There has been a raft of students who have also helped behind the scenes either contributing their time and knowledge into the scheme or offering their brawn in the often harsh task of field work. Thanks to Shanshan Li, Mina Lee, Tao Zhong, Youngnam Kim, Obed Lense, Victoria Henry, James Ranstead, Minakshi Mishra, Sally Seyedalikhani, Amata Yuan, Laine Weiskopf and Tristan Girdwood. And a big thank you to the Whenua Kura students who were a great help demonstrating their skills for weed management, eco-sourcing seeds and bivi building, all whilst smiling! The glasshouse work was made possible by Brent Richards and Leona Meachin whose knowledge, assistance, patience and humour made numerous trials achievable and enjoyable. And in the same vein, the laboratory work was made manageable by the knowledge, orgnisation and ever friendly facilitation of Roger Cresswell, Lynne Clucas and Leanne Haswell. The everyday running of the project has been largely helped by the organisation and secretarial assistance from Emma Gambles, Robyn Wilson, Gail Harkerss, Marianne Duncan and other secretaries and holders of knowledge and keys. Likewise, many trials would not have been possible had it not been for the patient assistance and knowledge of Myles Mackintosh. iv Thanks are extended to many university and CRI staff whose expertise have been invaluable in guiding us through the theory of soil scince, Canterbury Plains vegetation and restoration design including Colin Meurk, Brett Robinson, Jon Sullivan and Mick Abbott and the associated students who have been involved, including Kate Blackburne and Woody Lee. Organisations which have also been involved and generously given their time, advice or compost freely include Selwyn District Council, staff at Orana Wildlife Park, ECAN, QEII representative Miles Giller, Anita Spencer of DOC and the amazing knowledge of Nicky Robb at the Motukarara DOC nursery. Also a specieal mention to the Spencer-Bower family for allowing access to the kānuka remnant on their land, enabling numerous enlightening investigations and studies. Finally, thanks to my wonderful friends and family who have kept me sane throughout the long process. Thanks to my expert proof readers, Zoe Barrett, Adam Lawson and Tim Curran; my “mum gang” for giving me that extra time in the office and keeping my kids entertained including Penny Curran, Vic Wadhams, Debs Bratton, Kim McDrury and Lynne Wilkins; my long distance support, Shona McCombie and Rebecca Shelton; my wonderful mum, Hazel Dollery for being my mum; my band mates for giving me music and beer; my farming advisors, Sam, Ness and Sophie; and my lovely husband, Andy, and children, Skyler and Lochie, for putting up with my absence on camping trips. I look forward to spending so much more time playing Transformers, biking, colouring in and catching up on fun times I’ve missed. v Table of Contents Abstract ....................................................................................................................................... ii Acknowledgements ....................................................................................................................