Conservation and Ecology of Bryophytes in Partially Harvested Boreal Mixed-Wood Forests of West-Central Canada

University of Alberta Conservation and ecology of bryophytes in partially harvested boreal mixed-wood forests of west-central Canada by Richard Theodore Caners A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Conservation Biology Department of Renewable Resources ©Richard Theodore Caners Fall 2010 Edmonton, Alberta Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission. Examining Committee S. Ellen Macdonald, Renewable Resources, University of Alberta René J. Belland, Renewable Resources, University of Alberta Mark R. T. Dale, Biological Sciences, University of Northern British Columbia Dennis L. Gignac, Biological Sciences, University of Alberta Lars Söderström, Biology, Norwegian University of Science and Technology Abstract This thesis examined the efficacy of residual forest structure for the preservation and recovery of bryophytes five to six years after partial canopy harvest in boreal mixed-wood forests of northwestern Alberta, Canada. Bryophytes were sampled in two forest types that differed in pre-harvest abundance of broadleaf (primarily Populus tremuloides Michx. and P. balsamifera L.) and coniferous (primarily Picea glauca (Moench) Voss) canopy trees. In Chapter 2, epiphytic bryophytes growing on aspen (P. tremuloides) were characterized by species viability and nearest-neighbour relationships. Epiphyte assemblage structure showed increasing impact with declining retention owing to degradation of growing conditions for species on trees. Chapter 3 provided an analysis of species richness and abundance patterns in relation to residual canopy structure. Bryophytes generally benefitted from higher canopy retention; however, epixylic and epiphytic species were more sensitive to partial harvesting than species on other substrates, and liverworts were more sensitive than mosses. Liverworts exhibited higher among- site differences in richness as retention declined, which partly resulted from increasing numbers of local species extinctions. In an analysis of species- environment relations in partially-harvested forests in Chapter 4, forest moisture was reduced with any degree of harvesting in both forest types. Lower canopy retention and forest moisture levels were associated with reduced abundances of species with particular biological traits, such as limited reproduction and dispersal capacities. Their re-establishment after harvesting may be impeded because of biological and environmental limitations. Coniferous-dominated forests supported higher abundances of liverworts and species with greater moisture requirements than did mixed-wood broadleaf-coniferous forests, and are potentially important refuges of bryophyte source populations. Chapter 5 examined the capacity for bryophyte species to germinate from diaspore banks in forest soils. Species germinated readily from mineral soil samples obtained from harvested sites, including several perennials characteristic of intact forests. Diaspore banks may serve as a persistent source for species colonization at post-disturbance sites, but only under appropriate growing conditions and not for species that were most sensitive to harvesting. Overall, both amount and composition of forest structure retained after partial harvesting are important management considerations for ensuring conservation of the wide variety of bryophyte species in mixed-wood landscapes. Acknowledgements I would like to extend my gratitude to the numerous people whose guidance, assistance, and support made this undertaking a meaningful and enjoyable one; to those who provided financial support and made this research possible; and to a department that fostered a collegial and supportive professional working environment. I would particularly like to thank my co-supervisors, Ellen Macdonald and René Belland, for their valued direction and encouragement over the years. I am grateful to Ellen for always making time for helpful discussions, and answering and asking questions; for providing opportunities for professional development; and for constant support. I thank René for sharing his immense bryological expertise and enthusiasm, and for helping to expand my bryological knowledge one step at a time. Out of our many "mossing" excursions the week spent in Jasper National Park searching for Bartramia halleriana was especially memorable and instructive. My committee member Mark Dale was always available to meet and help work through my data and output with patience and insight. The many months of field work spent collecting data and specimens would not have been possible without assistance from Brett Bodeux, Lisa Matthias, Christine Quinlan, and Penny Wizniuk. Pete Presant provided technical and logistic support to ensure field work went as planned. Bruce Alexander ensured the resources needed to operate my growth cabinet experiments were always available, and Georgina Ivan and Lisa Matthias volunteered to monitor and tend to my germinating samples on several occasions. Financial support from the following agencies/organisations and individuals made this research possible, and was greatly appreciated. • Alberta Conservation Association, Challenge Grant in Biodiversity • Alberta Sport, Recreation, Parks, and Wildlife Foundation, Development Initiatives Program Grant • Canadian Circumpolar Institute, Circumpolar / Boreal Alberta Research (C/BAR) Grant • Department of Renewable Resources Graduate Teaching Assistantships • Ecological Society of America Student Section International Travel Award • EMEND project in-kind and logistic support, and the following project partners: Alberta Sustainable Resource Development, Canadian Forest Products Ltd., Daishowa-Marubeni International Ltd., and Manning Diversified Forest Products • Graduate Student’s Association Professional Development Grants • Herbert and Jeanette Hall Graduate Scholarship • Izaak Walton Killam Memorial Scholarship • John and Patricia Schlosser Environment Scholarship • Mary Louise Imrie Graduate Student Award • NSERC operating grant to S. Ellen Macdonald • Sustainable Forest Management Network HQP Travel Award • Sustainable Forest Management Network operating grant to S. Ellen Macdonald • University of Alberta Dissertation Fellowship • University of Alberta Ph.D. Scholarship • West Fraser Scholarship in Enhanced Forest Management The support staff in the Department of Renewable Resources provided ongoing professional assistance, which was greatly appreciated. Sandy Nakashima (decd.) arranged for graduate funding before I arrived in Edmonton and ensured I never missed an important deadline. Wilf Schofield (decd.) (University of British Columbia) shared conversation and encouragement during our few meetings before his untimely passing, Jennifer Doubt (Canada Museum of Nature) provided insightful discussions on species identification and taxonomy, and Kell Damsholt (Botanical Museum, University of Copenhagen) graciously identified several liverwort specimens. Thank you to Colin Bergeron, Jason Edwards, Joyce Gould, Charlene Hahn, Todd Kemper, and Dave Locky for close friendships, continuous encouragement, and enlightening conversations. The Macdonald lab group (affectionately known as "Clan Mac"), both past and recent, were always eager to offer new perspectives and insightful feedback. I owe a special thanks to my family and especially to Lisa Matthias, my wife. Lisa was always the first person to review my work and provide feedback, and has been immensely supportive throughout my program. Lisa, this would not have been possible without you. Table of Contents Chapter 1: Introduction 1 1.1 Factors influencing bryophyte diversity in boreal forests 2 1.2 Effects of forest harvesting on bryophytes 4 1.3 Potential benefits of partial canopy retention after harvesting 6 1.4 Literature cited 10 Chapter 2: Responses of boreal epiphytic bryophytes to different levels of partial canopy harvest 21 2.1 Introduction 22 2.2 Methods 25 2.3 Results 31 2.4 Discussion 36 2.5 Acknowledgements 43 2.6 Literature cited 43 Chapter 3: Bryophyte community recovery after partial forest harvesting depends on residual canopy structure 60 3.1 Introduction 61 3.2 Methods 64 3.3 Results 70 3.4 Discussion 73 3.5 Acknowledgements 80 3.6 Literature cited 81 Chapter 4: Biological traits of boreal bryophytes explain species sensitivity to habitat change after partial harvesting 106 4.1 Introduction 107 4.2 Methods 110 4.3 Results 118 4.4 Discussion 120 4.5 Acknowledgements 128 4.6 Literature cited 128 Chapter 5: Recolonization potential of bryophyte diaspore banks in harvested boreal mixed-wood forest 157 5.1 Introduction 158 5.2 Methods 160 5.3 Results 164 5.4 Discussion 166 5.5 Acknowledgments 172 5.6 Literature cited 172 Chapter 6: Summary and implications 190 6.1 Effectiveness of residual forest structure for maintaining bryophytes 191 6.2 Species dispersal capacity

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