COMPARATIVE SEED ECOLOGY OF NATIVE AND ALIEN PLANTS OF OPEN UPLANDS Christopher Sean Blaney A thesis submitted in conformity with the requirements for the degree of Master of Science Graduate Department of Botany University of Toronto O Copyright by Christopher Sean Blaney 1999 National Library Bibliothèque nationale 1*1 of Canada du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395, nie Wellington Ottawa ON K1A ON4 Ottawa ON K 1A ON4 Canada Canada The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant a la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sel1 reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or electronic formats. la forme de rnicrofiche/film, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fiom it Ni la thèse ni des extraits substantiels may be printed or othewise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. auton sation. COMPARATNE SEED ECOLOGY OF NATIVE AND ALIEN PLANTS OF OPEN UPLANDS Master of Science 1999 Chnstopher Sean Blaney Department of Botany University of Toronto Plant invaders may gain an advantage over natives because only enemy-free species are likely to invade (the predator filter hypothesis), or because invaders lose enemies while moving to a new area (the predator escape hypothesis). Working at the Joker's Hill Field Station, near Newmarket. Ontario, 1 bave combined site descriptions, surveys. and experiments to investigate the role of predaton and pathogens in seed ecology, and to understand their role in the establishment and spread of exotic species. Results indicate that seeds of both natives and exotics suffered significant losses to above- ground predators and below-ground pathogens. Losses vaned among species and habitats; wrtlands had particularly high levels of fungal mortality. Aliens and natives did not consistently differ in their susceptibility to predators and pathogens, even when analyzed using methods that controlled for phylogenetic biases. These results suggest natural enemies of seeds do not as a general rule determine invasive ability. ACKNOWLEDGEMENTS Many people contributed to making my time as a Master's student enjoyable and rewarding, and 1 will do my best to recognize them al1 here. To those 1 have left out, my apologies, 1 am wnting this just hours before I have to submit, but to everyone my deepest thanks. First and foremost 1 should recognize the efforts of my supervisor Professor Peter Kotanen, who was unceasingly attentive to my needs and generous with his tirne, advice and funding. 1 could not have completed this project without his help. He has gone well above the effort required of a supervisor and has taught me a great deal. 1 feel privileged to have worked with him as a student and as a friend. 1 have also benefitted greatly from the guidance and suggestions of al1 of the mernbers of n~ysupervisory cornmittees, which have included Profesors David Wedin, Spencer Barrett. Robert Jefferies and Gary Sprules. Aside from my committee, Professor Linda Kohn provided advice on a nurnber of issues related to soi1 fungi, and Professor Peter Bal1 was always ready to assist in the identification of tricky plant specimens. Interactions with many student colleagues have helped shape and sharpen rny academic skills as well providing happy diversions. Che Elkin. Marc Johnson, Luc Bussiere, Brendon Larson, Patrick Lorch, Andrea Case and rny fellow seed bank afficionado Esther Chang deserve special mention in this regard. Jutta Stein, Greenhouse Technician at the University of Toronto at Mississauga deserves pürticular individual recognition. She went to great efforts to ensure my plants survived in the greenhouse. She always made space for my odd assortment of rather weedy specirs, even when they were spreading into ber pots. Her efforts not only allowed me to complete my thesis, but also enabled me to confidently have a life on weekends, knowing the crucial plants were well taken care of. My work was aided substantially by the numerous field and laboratory assistants, paid and unpaid, who spent time in the Kotanen lab - Michelle Tseng, Sonya Carl, Arthur Poon, Joel Sotomayor, Sandra Benvenuto, Sheenagh Bell, Bill Kilburn, Carl Rothfels, Vijanti Ramlogan, Reagan Szabo, Marc Johnson and Uyen Dias. Not only did they offer able assistance on many difficult and repetitive tasks, they left me with many of my best, lasting memories of my time at Erindale. At the Joker's Hill field site, property manager William Fox was always available when needed and was generous with the sites resources. The donors of the property, Murray and Marvelle Koffler should also be recognized. They have given the University of Toronto a unique gift, the value of which it is only just beginning to fully recognize. The Joker's Hill property is a rare jewel in the southem Ontario landscape and was a joy to work at. I would also like to recognize my parents, who first inspired my love for the natural world and who have always been entirely supportive of my interests. Finally. to Becky Whittam, who has been my most important source of encouragement, sympathy. sustenance (literal and spiritual) and serene working conditions in the difficult tirnes leading to thesis completion. I thank you for your love and patience. TABLE OF CONTENTS Contents Page ABSTRACT ACKNOWLEDGEMENTS TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES CHAPTER 1 - General Introduction Overall Introduction Biological Invasions Seeds and Their Enemies Predator Escape and Predator Filter Hypotheses The importance of phylogeny Old Fields Objectives CHAPTER 2 - Vegetation of Joker's Hill Introduction Site overview Landfons and early human history of Joker's Hill Native plant communities: The historie setting Old fields: The study system Survey Methods The local species pool: Overall vascular plant species Species presence and abundance for main tkld sites Seed bank estimation for main field sites Results and Discussion Overall vascular plant species pool Rare native plant species Species presence and abundance at main field sites Seed bank estimation for main field sites Conclusions Contents - Pape CHAPTER 3 - Experimental Survey of Native and Alien Seed Mortality 36 Introduction 37 Methods 40 Study site 40 Experimental Species 4 1 Treatments 44 Soi1 srtrfnce seed predatinn experiment 44 Seed bank mortalin, experiment 45 Analysis 46 Resu lts 47 Soi1 surface seed predation experiment 47 Seed bank mortality experirnent 53 Discussion 72 Soi1 surface seed predation 72 Predator iden tity 72 Overd seed rernovcrl 72 Patterns in trentmerrt efects 74 Seed bank mortality experiment 75 Fwzg ideaddition 75 Invzrrebrate e.rclusion 76 Tenzporal pattern in seed recovery 77 Treatment efsecrs vs. seed size 78 Twonomic pattenz 78 Aliens vs. Natives 79 Contents Pape CHAPTER 4 - Comparative Experiments on Fungal and Habitat Effects on Seed Bank Mortality Introduction Methods Study site Experimental Species Treatments Analysis Results Overüll seed recovery Overall effects of fungicide addition Variation in seed recovery between species Variation in recovery by origin Discussion Does fungal mortality influence seed persistence in the soi1 seed bank? Do seed recovery and fungal mortality vas, between wetland and upland meadows? Does fungal mortality Vary betwren closely related natives and alirns? CHAPTER 5 - General Conclusions Achievernent of thesis objectives a) to provide background information on the site and biological setting of the experiments b) to determine whether seeds suffer significant losses to predators before incorporation into the seed bank C) to deterrnine whether seeds suffer significant losses to seed predators and uathooens in the seed bank Contents Page CHAPTER 5 (cont'd) d) to discover whether seed losses to naturd enemies differ among species 104 e) to determine whether seed losses to natural enemies differ between habitats 1O4 f) to determine whether seeds of native and alien species differ in their susceptibility to natural enemies 105 g) to determine whether differences in seed losses between natives and aliens occur independent of their phylogenetic relationship 105 Limitations of the work 1 O5 General Conclusions 1 O6 LITERATURE CITED 1 O7 APPENDIX 1 - Vascular Plants of Joker's Hill 1 APPENDIX II - Rare Native Vascular Plants of Joker's Hill XX APPENDIX III - Birds of Joker's Hill XXI 1 APPENDIX IV - Mammals of Joker's Hill XXVI APPENDIX V - Reptiles and Amphibians of Joker's Hill XXVII vii LIST OF TABLES Table 2.1. Species present at Dead Man's Curve and Wet Meadow field sites, within the area of the Kotanen plots. Table 2.2. Abundance of species found in intensively sampled plots at Dead Man's Curve field site. Table 2.3. Abundance of species found in intensively sampled plots at Wet Meadow field site. Table 2.4. Geninable seed banks (mean seedslm2 2 SEM) from top and bottoni halves of cores from Dead Man's Curve and Wet Meadow field sites, fall 1997 and spring 1998 trials. Table 2.5. Garminable seed bank (mean seeds/m2 to IO cm depth t SEM) at the Dead Man's Curve field site, fdl 1997 and spnng 1998. Table 2.6. Germinable seed bank (mean serdslrn2 to IO cm depth - SEM) at the Wet Meadow field site, fdl 1997 and spring 1998. Table 3.1. Experimental species for seed bank mortrility and soi1 surface seed predation experiments, indicating presence on Joker's Hill research station property, and at the Dead Man's Curve research site. Table 3.2. Resuks of seed predation experiment: Mean proportional seed recovery +. SEM.