Federico Riva
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Responses in butterflies to loss and fragmentation of boreal forests from in situ oil sands by Federico Riva A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Conservation Biology Department of Renewable Resources University of Alberta © Federico Riva, 2019 Abstract Anthropogenic loss and fragmentation of habitat are a threat to biodiversity, while increasing demands for energy have made the provision of fossil fuels an important source of disturbance to habitats around the globe. In Alberta, Canada, the extraction of a 142,000 km2 oil sands reserve is causing one of the largest examples of habitat fragmentation worldwide. Approximately 97% of Alberta’s reserves are located underground, and thus are accessible only using subsurface wells, a practice defined as “in situ” extraction. In situ extraction of oil sands results in little overall loss of boreal forest habitat, usually limited to less than 20% of forest cover, but it causes high levels of forest fragmentation, with up to 50 km of linear features per km2 of forest. Although in situ oil sands affect vast areas of the boreal biome, and despite many important services provided by insects in boreal ecosystems, virtually no information is available on responses in insect taxa. In this thesis, I assessed how butterflies responded to the disturbance footprint associated with in situ oil sands in the boreal forests of northeastern Alberta, Canada, with a specific focus on the effects of seismic lines. First, I assessed changes in butterfly assemblages as a function of different disturbance types and measures of landscape fragmentation. I found consistent, positive effects of in situ disturbances on butterfly diversity and abundance, and small effects of landscape in moderating the local composition of butterfly assemblages. Notably, while even “conventional” seismic lines substantially increased butterfly diversity and abundance, “low- impact” seismic lines were successful in mitigating this response. Second, I used experimental releases of arctic fritillaries (Boloria chariclea) to assess if corridors affect the movement of a habitat generalist butterfly. Both low-impact and conventional lines equally conditioned the movement of arctic fritillaries, directing butterflies toward the line direction. Effects were ii independent from forest and corridor characteristics, as well as the sex of the butterflies. Third, I studied how cranberry blue butterflies (Agriades optilete) responded to in situ oil sands disturbances and wildfires. As with most other butterfly species, I observed more cranberry blues in seismic lines. Yet, cranberry blues avoided well pads and were rare in burned forests, suggesting sensitivity to forest disturbance of this species. Last, I examined how the presence of seismic lines in burned forests conditioned plant and butterfly populations one year after the Fort McMurray Horse River wildfire (2016). By reducing wildfire severity, seismic lines retained the initially more diverse plant and butterfly assemblages, even in severely burned forests, suggesting that these anthropogenic linear features can act as “refugia” for species negatively affected by wildfire. Overall, this work demonstrated strong responses in butterflies to forest disturbances associated with in situ oil sands, suggesting that substantial effects could occur for numerous invertebrate taxa that inhabit these forests. While most boreal butterflies depend on early seral stages of the forest succession, and thus benefit from the patches of early seral forest associated with in situ disturbances, organisms that depend on mature forest stages may suffer from negative effects due to loss and fragmentation of mature forest habitat. Mitigating the effects of the widespread disturbance footprint associated with in situ oil sands remains a priority, and reducing line width to less than 5 m confirmed an effective mitigation practice not only for vertebrates, but also for butterflies. iii Preface This thesis is an original work from Federico Riva. Chapter 2 has been published as: F. Riva, J.H. Acorn, S.E. Nielsen (2018) “Localized disturbances from oil sands developments increase butterfly diversity and abundance in Alberta's boreal forests”. Biological Conservation 217, 173-180. F. Riva was responsible for research design, data collection, analysis, and manuscript composition. J.H. Acorn and S.E. Nielsen were involved with research design and manuscript edits. Chapter 3 has been published as: F. Riva, J.H. Acorn, S.E. Nielsen (2018) “Narrow anthropogenic corridors direct the movement of a generalist boreal butterfly”. Biology Letters 14 (2), 20170770. F. Riva was responsible for research design, data collection, analysis, and manuscript composition. J.H. Acorn and S.E. Nielsen were involved with research design and manuscript edits. Chapter 4 has been published as: F. Riva, J.H. Acorn, S.E. Nielsen (2018) “Distribution of cranberry blue butterflies (Agriades optilete) and their responses to forest disturbance from in situ oil sands and wildfires”. Diversity 10 (4), 112. F. Riva was responsible for research design, data collection, analysis, and manuscript composition. J.H. Acorn and S.E. Nielsen were involved with research design and manuscript edits. Chapter 5 was developed in collaboration with Jaime Pinzon, from the Canadian Forest Service. F. Riva was responsible for research design, data collection, analysis, and manuscript composition. J. Pinzon, J.H. Acorn and S.E. Nielsen were involved with research design and manuscript edits. iv Acknowledgments I am deeply grateful to Scott Nielsen and John Acorn for mentoring me in the past four years. They taught me many critical lessons, leading by example with empathy, knowledge, and an inspiring love for nature and teaching. Their influence transcended my mere professional growth, and I am appreciative for their unconditional patience and support. Felix Sperling and Nick Haddad honored me with their presence in the supervisory committee of this doctorate. Experiencing their scientific rigor and critical mindset was a turning point in my vision of science, and pushed me constantly to raise my standards. Likewise, John Spence and Nadir Erbilgin provided important insights before and during my candidacy exam, Jaime Pinzon contributed with essential ideas throughout our collaboration, and Anne Naeth and the whole Land Reclamation International Graduate School provided fundamental support and training. Many members of the ACE Lab were important during the past years. I was fortunate to meet Caroline Martin, who has been the sweetest and most patient partner. Zachary MacDonald was an incredible source of ideas and debate. Diana Stralberg provided feedback on analysis and methods. Catherine Denny and Trish Fontaine were inextinguishable sources of support. Angelo Filicetti was an integral part of the field season, and a good friend before being an example of dedication and endurance. I thank Chloe Christenson, Shawn Eckert, Victoria Masquillier, Fionnuala Carrol, and Marcel Schneider for assisting me while conducting field work. I was fortunate to meet many friends in Edmonton. Emmanuel Romero and Francesco Gentile are now two of my closest friends, and I thank them for their unconditional support. Liam Heffernan, François-Nicolas Robinne, Autumn Watkinson, and Kevin Hawkshaw were important presences in everyday life. I thank Christie Nohos and Marina Offengenden for v constant help and kindness in the University, and Jennifer Barker for crucial insights on the delicate balance between private life and career. Part of my heart remains in Italy, and I thank my family for the sacrifices and efforts sustained to educate me. I also thank Federico Giacherio, a constant support and true friend, and Simona Bonelli, Francesca Barbero, Luca Casacci and Emilio Balletto from the University of Turin, for their trust and the relationship that still keep us close. Finally, I acknowledge the many organizations that supported this doctorate: • COSIA; • Alberta Innovates - Energy and Environmental Solutions; • Alberta Agriculture and Forestry; • NSERC - CRD; • Land Reclamation International Graduate School, with a “NSERC - CREATE”; • Department of Renewable Resources at the University of Alberta, with a “Doctoral Recruitment Scholarship”, a “Len Leskiw Graduate Award”, and a “Dr. Ian G. W. Corns Memorial Scholarship”; • University of Alberta Graduate Students Association, with a “Green and Gold Leadership Award” and a “GSA Academic Travel Award”; • The Xerces Society, with a “Joan Mosenthal DeWind Award”; • Alberta Conservation Association, with a “Grant in Biodiversity”; • US-IALE, with a “Student Travel Award”. vi Table of Contents Abstract ........................................................................................................................................... ii Preface............................................................................................................................................ iv Acknowledgments........................................................................................................................... v List of tables ................................................................................................................................... xi List of figures ................................................................................................................................ xii Chapter 1: Introduction ..............................................................................................................