Effects of Climate, Historical Logging and Spatial Scales on Beetles in Hollow Oaks
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Effects of climate, historical logging and spatial scales on beetles in hollow oaks Betydningen av klima, historisk hogst og omgivelser for biller i hule eiker Philosophiae Doctor (PhD) Thesis Hanne Eik Pilskog Department of Ecology and Natural Resource Management Faculty of Environmental Science and Technology Norwegian University of Life Sciences Ås 2016 Thesis number 2016:90 ISSN 1894-6402 ISBN 978-82-575-1404-4 PhD Supervisors Professor Anne Sverdrup-Thygeson Department of Ecology and Natural Resource Management Norwegian University of Life Sciences Professor Tone Birkemoe Department of Ecology and Natural Resource Management Norwegian University of Life Sciences Researcher, Dr. Marianne Evju Norwegian Institute for Nature Research (NINA) Evaluation committee Professor Thomas Ranius, Department of Ecology Swedish University of Agricultural Sciences Researcher, Dr. Therese Johansson Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences Committee administrator: Researcher, Dr. Katrine Eldegard Department of Ecology and Natural Resource Management Norwegian University of Life Sciences ii “Lengthy forest logging and the related use of timber and sawmills have caused grave damage to his Majesty the King and driven the country into ruin” —Report to the Danish-Norwegian King regarding the state of the Norwegian oak forests in 16311 1 Translated to English from Tvethe, M. B. 1852. Bidrag til Kundskab om Skovenes Tilstand i det 17de Aarhundrede. Norske Samlinger. Feilberg & Landmark, pp. 112-119 iii iv Acknowledgements Four years have passed quickly, and this PhD have given me opportunity to investigate and learn about the fascinating world of deadwood-dependent insects living in the oldest beings you are likely to encounter—centuries old oaks. But this PhD have also given me the chance to get involved in teaching of zoology, entomology and nature management courses, of which I am very grateful. I wish to thank Anne Sverdrup-Thygeson and Tone Birkemoe that introduced me to this fascinating subject and guided me through my PhD. You have always been supportive, enthusiastic and helpful whenever I needed help or feedback. Anne, you are exceptionally structured with the latest literature close at hand, and you are expert number one whenever I had questions about hollow oaks. I do not understand how you get time to do all the things you are involved in and still answer emails rapidly, often within minutes. Tone, you always have a positive attitude and your door was always open whenever I had things to discuss. Teaching in your entomology course has been one of the highlights during my PhD period! Marianne Evju, your practical approach and knowledge in statistics have been indispensable and I am glad you wanted to join as a supervisor. A big thank you also goes to the co-authors on the papers included in this thesis: Leonie Gough, Erik Framstad, Nicklas Jansson, Per Milberg and Mats Jonsell for sharing data and good collaboration. I am grateful to all my colleagues and fellow PhD students for making a good working environment and making my stay at the department (INA) so pleasant. Thank you Rannveig for being the best PhD-fellow I could possibly share office with. We both work with beetles in deadwood and I have enjoyed very much your enthusiasm for insects, the teaching, field courses and social evening we have v shared together! Thank you Markus, Christian, Mari, Walid, Anne, Carolin, Rafal and Victor for many PhD lunches and discussions. I am also thankful to everyone who joined our weekly ‘insect lunches’ (that ironically enough has not involved eating insects yet!). I therefore thank Tone Granerud, Vidar Selås, Paal Krokene, Nina Trandem and Daniel Münch for being so active in this group. I thank Adrian Rasmussen and Ingrid Gulliksen for being good company during the zoology teaching in the lab. Senia Hagen, thank you for letting me supervise you on your master thesis and making supervising seem like an easy job. My PhD period would not have been the same without my friends in Vingulmark and the adventures we have shared together. Nothing takes your mind off the thesis quicker than (re-enactment) fencing! I have also enjoyed the evenings with Daniel, Carita, Marion, Sunniva and Kjetil that made the transition to Østlandet very welcoming. I am also grateful to Hannaliza for proofreading my thesis on short notice! Lastly, I must thank my family, first and foremost: Knut, Jenny, Anders, Audun and Linn, you have been very supportive since day one and I am sorry my visits during the summers have been short stops in-between my field work. Alena and Peter, I am glad that you now are part of our family. I dedicate this thesis to my mother, Aase Randi Eik, who always believed in me and that I will miss very much. Hanne Eik Pilskog Ås, 30. September 2016 vi Table of contents Acknowledgements ............................................................................................... v List of papers ........................................................................................................ ix Summary .............................................................................................................. xi Sammendrag ........................................................................................................ xv Synopsis ............................................................................................................. xix Introduction ........................................................................................................... 1 Objectives ....................................................................................................... 3 Methods ................................................................................................................. 5 Study system and insect sampling ..................................................................... 5 Description of each study .................................................................................. 6 Paper I ............................................................................................................ 6 Paper II ........................................................................................................... 8 Paper III - IV .................................................................................................. 9 Main results ......................................................................................................... 13 Paper I .............................................................................................................. 13 Paper II ............................................................................................................. 14 Paper III ........................................................................................................... 16 Paper IV ........................................................................................................... 17 Discussion ........................................................................................................... 20 Only specialists are affected by climate .......................................................... 21 Tree and local scale ......................................................................................... 22 Patch size and habitat quality ....................................................................... 22 Small-scale isolation .................................................................................... 24 Semi-specialists and specialists respond differently to the environment .... 25 Landscape and regional effects ....................................................................... 26 Historical logging is influencing the species richness in hollow oaks ............ 27 Concluding remarks and management implications ....................................... 28 References ........................................................................................................... 31 vii Paper I Paper II Paper III Paper IV viii List of papers This thesis consists of the following papers, referred to by the Roman numerals (I−IV) in the text: Paper I Gough L.A., Sverdrup-Thygeson A., Milberg P., Pilskog H.E., Jansson N., Jonsell M. & Birkemoe T. (2015) Specialists in ancient trees are more affected by climate than generalists. Ecology and Evolution 5, 5632-41. Paper II Pilskog H.E., Birkemoe T., Framstad E. & Sverdrup-Thygeson A. (2016) Effect of habitat size, quality, and isolation on functional groups of beetles in hollow oaks. Journal of Insect Science 16, 1-8. Paper III Pilskog, H. E., Sverdrup-Thygeson, A., Evju, M., Framstad, E. and Birkemoe, T. Long-lasting effects of logging on beetles in hollow oaks. Submitted. Paper IV Pilskog, H. E., Birkemoe, T., Evju, M. and Sverdrup-Thygeson, A. Investigating species composition of beetles in hollow oaks reveals management-relevant patterns. Manuscript. Paper I-II are open access journals distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/3.0/) (Paper I) and Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) (Paper II). ix x Summary Veteran trees are keystone structures and important biodiversity habitats, but they are declining on a global scale. In Europe, old oaks (Quercus spp.) are one of the most important habitat trees for biodiversity, yet the knowledge about most of these associated species is limited. One important