University of Calgary PRISM: University of Calgary's Digital Repository Graduate Studies The Vault: Electronic Theses and Dissertations 2015-12-16 Scaling of Density-Dependent Reproduction in Bee-Pollinated Forbs of Logged Forests Johnson, Sarah A. Johnson, S. A. (2015). Scaling of Density-Dependent Reproduction in Bee-Pollinated Forbs of Logged Forests (Unpublished master's thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/27709 http://hdl.handle.net/11023/2685 master thesis University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. Downloaded from PRISM: https://prism.ucalgary.ca UNIVERSITY OF CALGARY Scaling of Density-Dependent Reproduction in Bee-Pollinated Forbs of Logged Forests by Sarah Alexandra Johnson A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE GRADUATE PROGRAM IN BIOLOGICAL SCIENCES CALGARY, ALBERTA DECEMBER, 2015 © Sarah A. Johnson 2015 ABSTRACT Plant reproduction can be impacted by a variety of influences at a range of spatial scales. In the face of accelerating anthropogenic habitat disturbance, it is worth understanding how communities function within highly altered landscapes. I examined how seed size and number varied for nine species of understory forb within logged foothills forests of southern Alberta. I examined local relationships between reproductive output and floral neighbourhood, bee abundance, and habitat variation, and how these might be modified along a gradient of landscape-scale clearcut logging. I found that local variables best explained plant seed production, and heterospecifics were generally more beneficial than expected. Further, logging in the landscape modified local interactions above a threshold point of approximately 50% logging in a 1.77 km2 area, predominantly for more habitat-specialized species. These results have implications for forest management, and for the importance of testing for interactions between explanatory variables, even across spatial scales. ii ACKNOWLEDGEMENTS This thesis only came to fruition due to the help of multiple people and funding sources, and I am forever in their debt. Thank you to Ralph Cartar for guiding me through and out the other side of many treacherous graduate school peaks and troughs; I could not have asked for a more supportive and knowledgable supervisor. Thank you to my committee members (new and old) and my external examiner for their words of wisdom and guidance along the way: Kathreen Ruckstuhl, Jana Vamosi, Paul Galpern and David Goldblum. Thank you to my parents, NSERC CANPOLIN, NSERC graduate scholarships, and ACA Biodiversity Grants for their contributions to my project and salary funds (and a bit of extra thanks to Mom and Dad). Thank you to Michelle Seifert, Evan Whitmore, Savannah Steinhilber, and Mary Fleet for help with collecting, counting, measuring, and entering data for an obscene number of seeds. Thank you to Stevi Vanderzwan and Stephen Hausch for their comaradery and support during the final thesis- writing push. Thank you to Kyle Wilson for his unwavering emotional support and lots of help with analyses, coding, and editing. Thank you to the past and present members of the Cartar Reid lab for being there for me when I needed it, especially: Alex Farmer, Riley Waytes, Sam Robinson, Rola Kutby, Jenn Retzlaff, Megan Goulding, Leanna Lachowsky and Haydeé Peralta- Vásquez. Without all of these people (and more) believing in me, I definitely wouldn’t have made it this far, and I am eternally grateful. iii TABLE OF CONTENTS ABSTRACT .................................................................................................................................... ii ACKNOWLEDGEMENTS ........................................................................................................... iii TABLE OF CONTENTS ............................................................................................................... iv LIST OF TABLES ......................................................................................................................... vi LIST OF FIGURES ..................................................................................................................... viii LIST OF APPENDICES ............................................................................................................... xii CHAPTER 1: GENERAL INTRODUCTION ................................................................................1 CHAPTER 2: REPRODUCTION OF UNDERSTORY FOREST FORBS: THE RELATIVE EFFECTS OF FLORAL NEIGHBOURHOOD, POLLINATORS, AND HABITAT ACROSS SPATIAL SCALES .........................................................................................................................8 2.1 Introduction ............................................................................................................................8 2.1.1 Background ......................................................................................................................8 2.1.2 Hypotheses and predictions ...........................................................................................14 2.2 Methods ................................................................................................................................20 2.2.1 Field sites .......................................................................................................................20 2.2.2 Study species .................................................................................................................20 2.2.3 Sampling design ............................................................................................................22 2.2.4 Sample processing .........................................................................................................25 2.2.5 Spatial scale ...................................................................................................................26 2.2.6 Data analysis ..................................................................................................................27 2.3 Results ..................................................................................................................................30 2.3.1 Spatial scale ...................................................................................................................30 2.3.2 Variable effects ..............................................................................................................35 2.4 Discussion ............................................................................................................................46 CHAPTER 3: CROSS-SCALE INTERACTIVE EFFECTS OF LOGGING ON UNDERSTORY FORB REPRODUCTION .............................................................................................................66 3.1 Introduction ..........................................................................................................................66 3.1.1 Background ....................................................................................................................66 3.1.2 Hypotheses and predictions ...........................................................................................70 3.2 Methods ................................................................................................................................73 3.3 Results ..................................................................................................................................77 3.4 Discussion ............................................................................................................................91 CHAPTER 4: GENERAL DISCUSSION .....................................................................................97 LITERATURE CITED ................................................................................................................100 APPENDIX A ..............................................................................................................................123 APPENDIX B ..............................................................................................................................125 iv APPENDIX C ..............................................................................................................................129 APPENDIX D ..............................................................................................................................136 v LIST OF TABLES Table 2.1: Simplified hypothesis table outlining expected relationships between variables and seed size and number, at both the local (=smaller) and patch (=larger) scales. ........................ 19 Table 2.2: Species of the most common bee-pollinated wildflowers sampled and analyzed for impacts on reproductive potential (seed size and number). Samples were collected in Kananaskis Country, AB from June-August 2012. The habitat counts indicate number of sites in which the species was sampled. Species are binned into three floral morphology categories, increasing in handling time for bumble bee visitors. ..................................................................................... 21 Table 2.3: Summary statistics