Faculty of Science and Engineering School of Molecular and Life Sciences The Patterns and Processes of Insect Pollinator Re-assembly across a Post-mining Restoration Landscape Emily Paige Tudor 0000-0002-2628-3999 This thesis is presented for the Degree of Master of Research (Environmental Science) of Curtin University January 2021 Declaration To the best of my knowledge and belief this thesis contains no material previously published by any other person except where due acknowledgment has been made. This thesis contains no material which has been accepted for the award of any other degree or diploma in any university. Invertebrate collections conducted for the purposes of this thesis were made under Fauna collection (scientific or other purposes) licences FO25000073 and FO25000230 provided by the Department of Biodiversity, Conservation and Attractions (Regulation 25; Biodiversity Conservation Regulations 2018). Additional funding was generously provided by Alcoa of Australia Ltd under the student placement agreement CW2270400 and in-kind support was generously provided by Kings Park Science. Signature: Date: 18th January 2020 i General Abstract Restoration ecology is rapidly evolving and growing in global significance for recovering habitat that has been damaged, degraded or destroyed. However, fauna remain an undervalued component of restoration as it is often assumed that fauna will return to restored landscapes following the reestablishment of vegetation. Insect pollinators are among the most biologically diverse and functionally important terrestrial taxa and serve to pollinate approximately 87.5% of all flowering plants. Therefore, insect pollinators play critical roles in the subsequent recruitment and community establishment of vegetation following restoration. However, the composition, structure, and function of insect pollinators in response to restoration has been largely overlooked within the Northern Jarrah Forest (NJF), where the impacts of restoration have otherwise been conspicuously well documented. This thesis presents an integration of in situ field and ex situ laboratory studies to provide a deeper insight into the patterns and processes underpinning the insect pollinator community reassembly in post-mining Jarrah Forest restoration. Insect pollinators were collected using vane trapping and trap nests across a sequence of restored sites to explore the community level responses of insect pollinators to the vegetation community and habitat structure. The insect community transitioned from bee-dominated to fly- and beetle-dominated assemblages along the restoration age gradient. Additionally, these communities were more responsive to changes in vegetation structure (i.e., density) than the abundance, richness, diversity, or composition of the vegetation community itself. Vegetation density was a strong correlate of thermal conditions in restoration sites in the NJF, which in turn had a significant effect on the reproductive responses of a key group of insect pollinators, the cavity-nesting Hymenoptera. Cavity-nesting bees responded strongly and positively to temperature increases associated with open, early successional habitat, while temperature had no significant effect on cavity-nesting wasps. The bees, in particular, had strong preferences for highly exposed, early-stage restoration sites, which were warmer than the rest of the chronosequence. These findings raised the question of what ecophysiological mechanisms were driving the preferences of the bee community, and the value of early successional patches for pollinators. Given the strong association between high environmental temperatures and nest site-selection, I quantified the thermal performance of both adult and larval cavity nesting bees as a potential ii mechanism driving this pattern, measuring metabolic rate as a proxy for developmental rates and energetic requirements. The cavity-nesting bee larvae possessed a ‘generalist’ thermal performance with a higher thermal tolerance and greater breadth compared to the cavity- nesting wasp larvae, a ‘thermal specialist’ with a reduced tolerance and narrower performance breadth. Moreover, comparisons between adult and larval Megachile aurifrons Latreille, 1802 demonstrated that cavity-nesting bee larvae had a lower thermal optimum and peak metabolic rate but greater performance breadth than adult conspecifics. Early successional restoration appears to optimise the thermal performance of M. aurifrons across both life-stages. In an ecological context, it is likely that the dominant cavity-nesters use a number of physiological and social behavioural adaptations for their habitat selection to stay within habitats that support their basic metabolic physiology and energetic requirements while minimising likelihood of parasitism. However, the precise mechanisms underpinning the responses of parasitoid wasps to vegetation structure remain unclear. Overall, the research in this thesis highlighted that that early successional restoration provides valuable habitat for the insect pollinator community primarily as a source of thermal refuge from the suboptimal conditions of the closed-canopy forest. These findings are highly relevant for future restoration efforts and suggest that density-reduction treatments may increase microclimate heterogeneity within dense, mature Jarrah Forest, and increase the suitability of these habitats to the pollinator community. However future research should explore the effects of forest thinning prior to broad-scale implementation to empirically inform adaptive management actions and maximise the biodiversity value of restored habitats. iii Acknowledgements Science is a collaboration, between many people, passions and professions and this thesis would not have been achieved without those who have contributed their time and support so generously. First and foremost, I wish to thank my supervisors, Dr Sean Tomlinson, Dr Adam Cross, and chairperson Bill Bateman, who provided unfailing assistance, encouragement, and patience every step of the way. I consider them all excellent academics in their own rights, effective mentors and genuine friends who have played critical roles in fostering my research journey and nurturing my passion for physiology, restoration, and ecology. A special thank you also goes to Wolfgang Lewandrowski, for his expert physiological knowledge, statistical wizardry, reassurance, and enough caffeine to get me though. For that and so much more, I am incredibly grateful to all of you. I extend my sincerest gratitude to Alcoa of Australia Ltd for providing additional funding for this research. To Andrew Grigg, for agreeing that the curiosities of the insect pollinator community was a worthwhile research investment. To Matthew Daws for his invaluable knowledge of the Jarrah Forest and providing perspective and opportunities that I would not have received otherwise and to Cameron Richardson for helping me wrangle the LiDAR data. A huge thank you also goes to Cameron Blackburn, for his outstanding plant identification skills, for saving any six-legged (or more) beasties for me to nerd out over and going above and beyond to make every site visit an enjoyable one. Thanks to all the staff and students in Kings Park Science, for accepting me in as one of their own and providing me access to the research and laboratory facilities: Thank you for the microscopes necessary to spends hours on end cleaning, sorting, and identifying insects, the incubators that kept bee and wasp brood cosy throughout development, X-rays to peer into nesting tubes and the Q2 scanner to deep dive into the respirometry trials. I am also incredible grateful to Emma Dalziell, for helping me learn how to swim after being thrown in the deep end with the Q2. To my field assistants, Luisa Ducki and Kieran Love, thank you for soaking up the sun with me on the gruelling summer scorchers or getting soaking wet from the dense thickets of water- bush. A special thank you must be extended to Sean again, for making himself available for iv almost every field day. Putting up with me in the field for 10-12-hour straight listening to endless rambling and Bon Jovi on repeat is no easy feat. To my botanical besties, Nate, Eloise, Luisa, thank you for embracing me as your crazy bug lady friend and sharing this journey with me. I am so grateful for your friendship, support and encouragement and every attempt made to convert me to the ‘plant-side’. Words cannot express how grateful I am to my parents. Mum and Dad, you two will always be the most important people in my life, and my entire academic journey is owed all to you. Thank you for your patience, support, endless love and for always accepting “but I’m writing my thesis” as a reasonable excuse to get out of other responsibilities. Everything that I do is an attempt to make you both proud and though neither of you will ever read this thesis in its entirety, it is dedicated to the both of you. Last, but not least, I also acknowledge the contribution of the thousands of insects that have formed a part of this study and fuelled my ever-growing obsession for anything creepy-crawly. Without you, the world as we know it would not exist. Insects of the Jarrah Forest © Emily Tudor v Statement of Contribution by Others Chapter Two: Integrating animal physiology and thermal biology into a descriptive and predictive restoration science I, Emily Paige Tudor, collected and analysed the data and led the writing of the manuscript; all authors contributed to revisions for the