Is Fuchsia excorticata (Onagraceae) seed limited? A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Ecology. By Rebecca Jane Hesley Bell School of Biological Sciences University of Canterbury March 2010 II Table of Contents List of Tables ............................................................................................................. VI List of Figures ............................................................................................................ IX Acknowledgements .................................................................................................... XI Abstract ..................................................................................................................... XII Chapter 1 - INTRODUCTION 1.1 Bird-plant mutualisms .............................................................................. 1 1.1.1 Overview ................................................................................... 1 1.1.2 Dispersal versus Pollination ...................................................... 2 1.2 Pollination limitation and crisis .............................................................. 4 1.2.1 Overview ................................................................................... 4 1.2.2 New Zealand Pollination limitation species ............................. 5 1.2.3 Limitation concepts and definitions .......................................... 6 1.3 Fuchsia excorticata ................................................................................... 8 1.3.1 Overview of the study species .................................................. 8 1.3.2 Possum browse and the declining distribution of Fuchsia excorticata................................................................................. 8 1.3.3 Breeding system – Gender dimorphism .................................. 10 1.3.4 Floral colour change ............................................................... 11 1.3.5 The potential for seed limitation in Fuchsia excorticata ........ 11 1.3.6 Restoration .............................................................................. 13 1.4 Overall objectives of this thesis………………………………………..14 Chapter 2 – STUDY SITES AND BIRD DENSITIES 2.1 Introduction ............................................................................................. 16 2.1.1 Site selection ............................................................................ 16 2.1.2 Hinewai Reserve, Banks Peninsula ......................................... 17 2.1.3 Mt Thomas, Canterbury........................................................... 19 2.1.4 St Arnaud, Nelson Lakes ......................................................... 20 2.1.5 Grampians Reserve, Nelson .................................................... 21 2.1.6 Pollen limitation ...................................................................... 23 2.2 Methods ................................................................................................. 23 2.2.1 Bird densities ........................................................................... 23 III 2.3 Results ................................................................................................. 24 2.3.1 Bird visitation .......................................................................... 24 2.3.2 Five minute bird counts ........................................................... 25 2.4 Discussion ................................................................................................. 29 2.5 Conclusions .............................................................................................. 31 Chapter 3 – NATURAL REGENERATION OF FUCHSIA EXCORTICATA SEEDLINGS (LIMITATIONS FOR RECRUITMENT) 3.1 Introduction ............................................................................................. 32 3.1.1 Microsites and environmental conditions ................................ 32 3.1.2 Objectives ................................................................................ 34 3.2 Methods ................................................................................................. 34 3.3 Results ................................................................................................. 35 3.4 Discussion ................................................................................................. 38 3.5 Conclusions .............................................................................................. 39 Chapter 4 – FUCHSIA EXCORTICATA IN THE SEED BANK 4.1 Introduction ............................................................................................. 40 4.1.1 What is a seed bank? .............................................................. 40 4.1.2 Fuchsia excorticata in the seed bank ...................................... 41 4.1.3 Dispersal away from the parent tree ........................................ 42 4.1.4 Objectives ................................................................................ 42 4.2 Methods ................................................................................................. 42 4.2.1 Field data collection and set up ............................................... 42 4.2.2 Data collection ......................................................................... 45 4.2.3 Statistical analysis ................................................................... 47 4.3 Results ................................................................................................. 47 4.3.1 Species diversity ...................................................................... 47 4.3.2 Abundance of Fuchsia excorticata in the seed bank .............. 52 4.3.3 Does Fuchsia excorticata abundance in the seed bank vary with dispersal distance away from the parent tree? ....................... 53 4.3.4 Pest control .............................................................................. 54 4.3.5 Hermaphrodite and female parent trees affect seed set ........... 56 4.4 Discussion ................................................................................................. 57 IV 4.4.1 Species diversity of the seed bank ........................................... 57 4.4.2 Overall abundance of Fuchsia excorticata seed in the seed bank ................................................................................................. 59 4.4.3 The effectiveness of the Fuchsia excorticata seed dispersal service ..................................................................................... 60 4.4.4 Ecosystem-wide effects of invasive species ............................ 61 4.4.5 Gynodioecy.............................................................................. 63 4.5 Conclusions .............................................................................................. 64 Chapter 5 – IN SITU SEED SOWING 5.1 Introduction ............................................................................................. 65 5.1.1 Seed sowing within the Fuchsia excorticata ecological community context.................................................................. 65 5.1.2 Seed sowing experiments – a background............................... 65 5.1.3 The effect of seed size on establishment ................................. 66 5.1.4 Objectives ................................................................................ 67 5.2 Methods ................................................................................................. 68 5.2.1 Location and layout ................................................................. 68 5.2.2 Slurry ....................................................................................... 68 5.2.3 Cages ....................................................................................... 69 5.2.4 Data collection ......................................................................... 72 5.2.5 Statistical analysis ................................................................... 72 5.3 Results ................................................................................................. 73 5.4 Discussion ................................................................................................. 77 5.4.1 Sowing extra seeds increases number of seedlings ................. 77 5.4.2 Cages and herbivore exclosure increases number of seedlings ... ................................................................................................. 78 5.4.3 Seedling recruitment declines with distance from the parent tree ................................................................................................. 79 5.5 Conclusion ................................................................................................ 80 Chapter 6 – DISCUSSION AND SYNOPSIS 6.1 Synopsis of experiments ........................................................................... 81 6.2 The wider picture ...................................................................................... 84 V 6.3 Implications: Restoration and avenues for change.................................... 86 6.4 Implications: Breeding system .................................................................. 88 6.5 Future research .......................................................................................... 88 6.6 Concluding remarks .................................................................................. 89 References .................................................................................................................