Clumped Planting Arrangements Can Improve the Ecological Function Of
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Clumped planting arrangements can improve the ecological function of revegetated eucalypt woodlands Kimberly P. McCallum A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy Department of Ecology & Environmental Science School of Biological Sciences The University of Adelaide October 2018 Table of Contents Published and submitted works included in the thesis ............................................ 3 Abstract .................................................................................................................... 4 Declaration ............................................................................................................... 6 Acknowledgements .................................................................................................. 7 Chapter 1. General introduction ............................................................................... 9 Chapter 2. Spatially designed revegetation ............................................................ 17 Spatially designed revegetation - why the spatial arrangement of plants should be as important to revegetation as they are to natural systems .......................... 18 Chapter 3. Seed production .................................................................................... 44 Clumped planting arrangements improve seed production in a revegetated eucalypt woodland ............................................................................................. 45 Chapter 4. Pollination ............................................................................................ 68 Plants, position and pollination – planting arrangement and pollination limitation in a revegetated eucalypt woodland ................................................... 69 Chapter 5. Genetics ................................................................................................ 91 Spatial aggregation promotes seed production and outcrossing, but not pollen diversity, in revegetated Eucalyptus leucoxylon ................................................ 92 Chapter 6. Natural plant arrangements ................................................................ 121 Using the spatial arrangement of natural plant communities to guide woodland revegetation ...................................................................................................... 122 Chapter 7. Revegetation design ........................................................................... 151 Spatially designed revegetation –manipulating the arrangement of seedlings during woodland revegetation .......................................................................... 152 Chapter 8. General discussion ............................................................................. 172 References ............................................................................................................ 184 Appendix 1. Supplementary material for Chapter 3 ............................................ 212 Appendix 2. Supplementary material for Chapter 5 ............................................ 214 Appendix 3. Supplementary material for Chapter 6 ............................................ 219 Appendix 4. Publications ..................................................................................... 222 ~ 2 ~ Published and submitted works included in the thesis McCallum KP, Lowe AJ, Breed MF and Paton DC (2018) Spatially designed revegetation – why the spatial arrangement of plants should be as important to revegetation as they are to natural systems. Restoration Ecology 26:446-455 https://onlinelibrary.wiley.com/doi/full/10.1111/rec.12690 McCallum KP, Breed MF, Paton DC and Lowe AJ (Accepted October 2018) Clumped planting arrangements improve seed production in a revegetated eucalypt woodland. Restoration Ecology ~ 3 ~ Abstract Revegetation is a key conservation activity in areas that have been extensively cleared and is undertaken in the hope it will prevent further species losses, mitigate land degradation and return functional ecosystems to degraded areas. Although revegetation has the potential to achieve these outcomes, the field is still relatively young and actively developing in terms of standards and best practice. As a result, the long-term viability, functionality and resilience of many re-planted systems remains uncertain. There have been calls for revegetation to move towards more ecologically informed designs and one way to achieve this is for plantings to mimic the composition and structure of natural vegetation. However, the outcomes of failing to undertake such practice is still poorly understood. The spatial arrangements of plants are central to natural communities and influence the majority of ecological processes that occur. Consequently, the position of plants within revegetated sites may affect the long-term viability and resilience of these restored systems. Despite this, planting arrangements are rarely considered an important feature of revegetated communities, especially for variables other than overall planting density and this may limit the ecological value of revegetated communities. The primary aim of this thesis was to examine how planting arrangements influence the ecological processes occurring within revegetated sites, with a focus on reproduction in woodland systems. I first review the available literature and synthesise information from natural ecosystems, plantation communities, and experimental plantings to identify ways plant arrangements may influence the ~ 4 ~ ecological function of revegetated systems and highlight key knowledge gaps. The data chapters of my thesis then evaluate how planting arrangement influences pollination, seed production, plant mating patterns and patterns of gene flow in a revegetated eucalypt woodland in southern Australia. Following this, I document the arrangement of plants within remnant eucalypt woodlands and identify key features that can potentially be incorporated into revegetation design if projects seek to re-create more natural woodland plant arrangements. I found that plant arrangements have the potential to influence a range of ecological processes, from those at the individual plant level (survival, growth), the population and community level (pollination, seed dispersal) and the ecosystem level more generally (habitat provision, erosion). My experimental results support these expectations and although plant reproduction was highly variable, the spacing between conspecifics and the degree of aggregation influenced seed production and plant mating patterns in the Eucalyptus species studied, whereas population abundance had little influence. Taken together, these findings suggest that woodland revegetation should consider not only the number of each species to be planted, but also the fine-scale arrangement (conspecific spacing, aggregation) of those species, if reproductively productive populations are to be established. One way to achieve this is to re- create more natural plant arrangements, where aggregation is common and large distances between conspecifics are rare. The challenge is now to find ways to effectively incorporate spatially designed revegetation into the planning and planting phases of revegetation and then monitor the outcomes of this approach. ~ 5 ~ Declaration I hereby certify that this work contains no material that has been accepted for the award of any other degree or diploma in my name in any university or other tertiary institution. To the best of my knowledge and belief, this work contains no material previously published or written by another person, except where due reference has been made in the text. In addition, I certify that no part of this work will, in the future, be used in a submission in my name for any other degree or diploma in any university or other tertiary institution without the prior approval of the University of Adelaide and where applicable, any partner institution responsible for the joint award of this degree. The author acknowledges that copyright of published works contained within this thesis resides with the copyright holder(s) of those works. I give consent to my thesis when deposited in the University library, being made available for loan and photocopying, when deposited in the University Library, subject to the provisions of the Copyright Act 1968. I acknowledge that copyright of published works contained within this thesis resides with the copyright holder(s) of those works. I also give permission for the digital version of my thesis to be made available on the web, via the University's digital research repository, the Library Search, and through web search engines, unless permission has been granted by the University to restrict access for a period of time. I acknowledge the support I have received for my research through the provision of an Australian Government Research Training Program Scholarship. Signature: Date: 30-Oct-18 ~ 6 ~ Acknowledgements Thank you to my primary supervisor David Paton for taking me on as PhD student, for sharing your knowledge of eucalypt woodlands and for introducing me to the Monarto revegetation area. Thanks for all the opportunities and guidance over the past few years and for trusting my ideas and directions. Thank you to my two co-supervisors Andy Lowe and Martin Breed. Andy – thank you for agreeing to supervise me again and for pushing me to do more when you knew I could, but for also telling me when to stop when I needed it. Martin – you were the unlucky one that