The Superb Lyrebird Menura novaehollandiae as an Ecosystem Engineer Submitted by Alex C. Maisey Dip. Cons. Land Mgt., Dip. Sust., B. Env. Sc. (Hons) A thesis submitted in total fulfillment of the requirements for the degree of Doctor of Philosophy Research Centre for Future Landscapes Department of Ecology, Environment and Evolution College of Science, Health and Engineering La Trobe University Victoria, Australia August 2020 Preface ii Contents List of Plates ................................................................................................................................. viii List of Tables .................................................................................................................................. ix List of Figures ................................................................................................................................. xi List of Appendices ........................................................................................................................ xiv Abstract ...........................................................................................................................................xv Statement of Authorship ............................................................................................................... xvi Acknowledgements ....................................................................................................................... xix Chapter One ......................................................................................................................................1 1.1 INTRODUCTION ...................................................................................................... 2 1.1.1 Ecosystem engineers: a definition and introduction ............................................ 2 1.1.2 Autogenic and allogenic engineering .................................................................. 3 1.1.3 Engineer vs. keystone species.............................................................................. 3 1.1.4 Types of ecosystem engineers ............................................................................. 4 1.2 Structural changes by engineers affect ecological processes and function ................ 5 1.2.1 Fire ....................................................................................................................... 5 1.2.2. Climate .............................................................................................................. 11 1.2.3 Hydrology .......................................................................................................... 11 1.2.4 Nutrient cycling ................................................................................................. 12 1.3. Scale and pattern of ecosystem engineering ........................................................... 12 1.3.1 Geographic scale ................................................................................................ 12 1.3.2 Spatial pattern .................................................................................................... 13 1.3.3. Temporal span and pattern................................................................................ 13 1.3.4 Abiotic legacies ................................................................................................. 14 ii Preface iii 1.4. Regulatory forces on ecosystem engineers ............................................................. 14 1.4.1 Feedbacks .......................................................................................................... 14 1.4.2 Interacting engineers .......................................................................................... 15 1.5. Trophic interactions with engineering ..................................................................... 16 1.5.1 Herbivory interacts with engineering ................................................................ 16 1.5.2 Predation interacts with engineering ................................................................. 16 1.6. Effects of introduced engineers ............................................................................... 17 1.7. Challenges to research on ecosystem engineers ...................................................... 17 1.8. Ecosystem engineers: an Australian context ........................................................... 18 1.8.1 Current and future direction of research on ecosystem engineering in Australia .................................................................................................................................... 19 1.9. Study species - the superb lyrebird ......................................................................... 19 1.9.1 Distribution ........................................................................................................ 20 1.9.2 Habitat................................................................................................................ 21 1.9.3 Breeding ............................................................................................................. 22 1.9.4 Foraging ............................................................................................................. 25 1.10. The superb lyrebird as an ecosystem engineer ...................................................... 26 1.10.1 Nutrient cycling ............................................................................................... 26 1.10.2 Litter and soil habitats ..................................................................................... 27 1.10.3 Vegetation composition and structure ............................................................. 29 1.11 Thesis – aims and objectives .................................................................................. 31 1.11.1 Overview of thesis chapters and key questions ............................................... 31 Chapter Two ....................................................................................................................................34 Abstract .......................................................................................................................... 35 2.1 INTRODUCTION .................................................................................................... 36 2.2 MATERIALS AND METHODS ............................................................................. 37 iii Preface iv 2.2.1 Study area .......................................................................................................... 37 2.2.2 Study design ...................................................................................................... 40 2.2.3 Foraging simulation ........................................................................................... 41 2.2.4 Effect of fencing on litter and soil ..................................................................... 41 2.2.5 Litter and soil displaced by lyrebirds ................................................................ 41 2.2.6 Structural complexity of vegetation .................................................................. 42 2.2.7 Physical characteristics of the soil ..................................................................... 42 2.2.8 Soil nutrients ...................................................................................................... 42 2.2.9 Statistical analysis .............................................................................................. 43 2.3 RESULTS ................................................................................................................. 46 2.3.1 Effect of fencing on litter ................................................................................... 46 2.3.2 Litter and soil displacement by lyrebirds .......................................................... 47 2.3.3 Foraging activity ................................................................................................ 47 2.3.4 Physical characteristics of the soil ..................................................................... 50 2.3.5 Soil nutrients ...................................................................................................... 51 2.4 DISCUSSION .......................................................................................................... 57 2.4.1 Scale and pattern of engineering........................................................................ 57 2.4.2 Impacts on litter and soil.................................................................................... 58 2.4.3 Implications for ecosystem function .................................................................. 58 2.5 CONCLUSION ........................................................................................................ 60 Chapter Three ..................................................................................................................................61 Abstract .......................................................................................................................... 61 3.1 INTRODUCTION .................................................................................................... 63 3.2 METHODS ............................................................................................................... 65 3.2.1 Study area .......................................................................................................... 65 3.2.2 Experimental treatments