Understanding and Forecasting Population Dynamics in Changing Arctic Ecosystems
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Faculty of Biosciences, Fisheries and Economics Department of Arctic and Marine Biology Understanding and forecasting population dynamics in changing arctic ecosystems A holistic approach to study the effects of environmental changes on arctic populations of management concern Filippo Marolla A dissertation for the degree of Philosophiae Doctor – August 2020 Table of Contents Acknowledgements ................................................................................................................................ 3 List of papers .......................................................................................................................................... 5 Summary ................................................................................................................................................. 7 1. Introduction ...................................................................................................................................... 11 A changing planet, a changing Arctic ............................................................................................ 11 Population dynamics in arctic tundra food webs .......................................................................... 12 Iterative forecasting to aid wildlife management .......................................................................... 14 2. Thesis objectives .............................................................................................................................. 17 Research questions .......................................................................................................................... 17 3. Methods ............................................................................................................................................ 20 Study systems ................................................................................................................................... 20 Target species .................................................................................................................................. 23 Conceptual models of climate and management impact .............................................................. 25 Data collection ................................................................................................................................. 27 Analytical methods .......................................................................................................................... 28 4. Results and discussion .................................................................................................................... 31 5. Conclusions and future perspectives .............................................................................................. 36 6. References ........................................................................................................................................ 41 Papers I-IV 1 2 Acknowledgements I cannot say that the journey was free of obstacles. Luckily, some amazing and brilliant people have supported me throughout. It is important for me to express my gratitude to all of them because this thesis is the result of a real teamwork. First, I would like to thank my unmatchable team of supervisors, possibly the largest ever, but also the best one. I like to refer to it as the “Jordan’s Chicago Bulls of ecology”. Rolf, for being such a supportive, enthusiastic, sympathetic leader. I have been profoundly inspired by your genuine passion for the natural world, your desire of understanding, your vision of how things should be done. I felt encouraged every time I needed. Thank you, I really mean it. Nigel, for truly having showed me what ‘thinking critically’ means. If today I strive to look at the world without prejudices, this is mostly because of you and I am grateful for that. John, for being always helpful, available, and especially patient when I needed extra explanations. It took me a while to master some techniques but you seraphically waited for me! Sandra, for regularly flooding my mind with waves of positive energy and a hail of brilliant insights whenever I got stuck. I felt supported even from another time zone. Eva, for being such an eager collaborator, but especially for having a nice word and a smile every time. You have this amazing ability of making people feel comfortable around you and I indeed felt that way working with you. The same goes for Åshild, the best field leader I could possibly have. Thank you for accepting me in the reindeer team, teaching me about Svalbard, and being nice when I lost my mind over a carbonara after a long hiking day…! Audun and Torkild, for the precious collaboration, fruitful discussions, and sincere willingness to participate in my work. I would like to thank all the co-authors of my papers, especially Tomas and Ingar. When I chose to study ecology, I meant to do ‘something good for nature’. I wanted my work to be a drop in the ocean of biological conservation. Working with you on the lesser white-fronted geese has been a privilege. I am inspired by the enthusiasm that, every summer, brings you up to Porsanger to give a chance to these fascinating, vulnerable birds. I hope that my contribution will turn out to be useful to you. I would like to thank Manolia, who I have not met yet but was awesomely helpful by sharing knowledge and data. A big thank you also to Marc and Michael, for making it easy for me to approach the world of integrated population modelling and for the authentic interest you showed in the goose study. I consider myself lucky to have joined you at Vogelwarte. Jarad recently joined the supervisor squad, but he deserves a separate paragraph. Thank you for being such a caring friend. For pushing me to look deeper, talk carefully, reconsider my assumptions, challenge my beliefs. And of course for all the steep lines we skied together. This may have been the steepest, but we made it! I have been so lucky to find a family above the Arctic Circle. Thank you Eivind, for being my Norwegian friend. If I felt welcome in Norway, that is mostly thanks to you (and Giron). Thank you Martin, for being such an amazingly kind and funny human being. You have no idea how much I miss laughing with you and the gang on a mountain slope, slowly climbing our way up to the top while dozens of skilled skiers that started way later than us are already flying down like bullets! Thanks to the ski crew; Hanna, Marita, Zina, Torunn, for the uncountable, memorable moments. Thanks to Chloé, for the technical support, but primarily for the precious friendship and the fun cohabitation. Thanks to Giacomo, Gigi, Paolo, and the other Italians who are trying to establish a colony in the Arctic, for making me feel not that far from our motherland. Thanks to all the 3 colleagues at the biology building for creating a positive working environment. And thanks to all the people that crossed my path over these four (and a half) years and shared their stories with me. A special thanks to Matteo. I left Italy thinking “I am not gonna look for other Italians when I’m there”, but I ended up finding a friend for life in a compatriot. Sharing thoughts, ideas, struggle, sporadic homesickness, and also R codes (!) with you has been more than important for me to get through it. You made it fun. Thanks to all the “femminielli” back in Rome. I cannot name all of you guys because you are way too many, but every time I came back it felt like no time had passed. Reading you arguing about whether Totti should retire or not on the groupchat made me feel like I was there all the time. Thank you Valentina, for being such a loving friend and the funniest woman I know. Thank you Rebecca, for the caring person you are and for having the courage to climb Tromsdalstinden as your first mountain. You made my time in Tromsø a lot easier even from far away. Thank you Simona, for pushing me to choose plan A over plan B five years ago. And thank you Losba, for calling me unexpectedly in the middle of the polar night just to let me listen to the new counter melodies you created over a song! A special thanks to my dearest friend Daniele. It has been now almost eighteen years walking side by side up to the Master degree and now the PhD, which though constitute only a tiny little part of the things we have achieved together. I would have never made it without our daily phone calls. It has really been a teamwork! Thank you. Thanks to northern Norway and the majestic beauty of its landscapes. More than once the view from a mountaintop, or just a gaze from my window over the peaks of Kvaløya, made me think that this a place to stay. Last but most important, the biggest thank you to my family. To Mum and Dad and Sister (and our dog Melany), I have no words to express how grateful I am for how supportive and loving you have been. You are my biggest inspiration and definitely, the first people I turned to when I had a hard time. Thanks for always being there for me. I love you so much. 4 List of papers Paper I. Marolla, F., Henden, J.A., Fuglei, E., Pedersen, Å.Ø., Itkin, M., Ims, R.A. (MS). Iterative model predictions for a high-arctic ptarmigan population impacted by rapid climate change. In Review in Global Change Biology. Paper II: Henden, J.A., Ims, R.A., Yoccoz, N.G., Asbjørnsen, E.J., Stien, A., Mellard, J.P., Tveraa, T., Marolla, F. and Jepsen, J.U., 2020. End-user involvement to improve predictions and management of populations with complex dynamics and multiple drivers.