Effects of Climate Change on Arctic Arthropod Assemblages and Distribution Phd Thesis
Total Page:16
File Type:pdf, Size:1020Kb
Effects of climate change on Arctic arthropod assemblages and distribution PhD thesis Rikke Reisner Hansen Academic advisors: Main supervisor Toke Thomas Høye and co-supervisor Signe Normand Submitted 29/08/2016 Data sheet Title: Effects of climate change on Arctic arthropod assemblages and distribution Author University: Aarhus University Publisher: Aarhus University – Denmark URL: www.au.dk Supervisors: Assessment committee: Arctic arthropods, climate change, community composition, distribution, diversity, life history traits, monitoring, species richness, spatial variation, temporal variation Date of publication: August 2016 Please cite as: Hansen, R. R. (2016) Effects of climate change on Arctic arthropod assemblages and distribution. PhD thesis, Aarhus University, Denmark, 144 pp. Keywords: Number of pages: 144 PREFACE………………………………………………………………………………………..5 LIST OF PAPERS……………………………………………………………………………….6 ACKNOWLEDGEMENTS……………………………………………………………………...7 SUMMARY……………………………………………………………………………………...8 RESUMÉ (Danish summary)…………………………………………………………………....9 SYNOPSIS……………………………………………………………………………………....10 Introduction……………………………………………………………………………………...10 Study sites and approaches……………………………………………………………………...11 Arctic arthropod community composition…………………………………………………….....13 Potential climate change effects on arthropod composition…………………………………….15 Arctic arthropod responses to climate change…………………………………………………..16 Future recommendations and perspectives……………………………………………………...20 References………………………………………………………………………………………..21 PAPER I: High spatial variation in terrestrial arthropod species diversity and composition near the Greenland ice cap……………………………………………………………………………….27 PAPER II: Meter scale variation in shrub dominance and soil moisture structure Arctic arthropod communities……………………………………………………………………………………..37 PAPER III: Diversity and composition changes along a continentality gradient in the Arctic……………..55 PAPER IV: Synchronous seasonal dynamics in composition, richness and turnover of arthropod assemblages across the Arctic…………………………………………………………………..97 PAPER V: Habitat-specific effects of climate change on a low-mobility Arctic spider species…………...122 PAPER VI: High-Arctic butterflies become smaller with rising temperatures……………………………..132 PAPER VII: Phenology of high-Arctic butterflies and their floral resources: Species-specific responses to climate change………………………………………………………………………………….136 As if some little Arctic flower, Upon the polar hem, Went wandering down the latitudes, Until it puzzled came To continents of summer, To firmaments of sun, To strange, bright crowds of flowers, And birds of foreign tongue! I say, as if this little flower To Eden wandered in – What then? Why, nothing, only Your inference therefrom! - Emily Dickinson 1860 PREFACE This thesis is the realization of three years’ work at the Department of Bioscience, Aarhus University, during which I have been stationed mostly at the Arctic Research Center, but also at the section for Biodiversity and conservation, Kalø. The fieldwork, which formed a large part of the thesis, was conducted in Nuuk, South-west Greenland during the summer of 2013. The thesis was supervised by Toke Thomas Høye with Signe Normand as co-supervisor, and I was also fortunate to be a part of a larger scientific collaboration with researchers from Canada, USA and Norway. The thesis is comprised of two main parts. An introduction of the general conceptual framework, preceding a summary of the results of the scientific papers, included in the thesis. Part two consists of seven papers. Paper I and II have been published in Polar Biology and PeerJ respectively. Paper III is in preparation for BMC Ecology and paper IV in preparation for Ecography. Paper V – VII have been published in Polar Biology, Biology Letters and Current Zoology, respectively. In this synopsis, I will first describe the patterns of global climate change and its amplification in the Arctic, which will set the scene for the main subject of my thesis; Overall impacts of climate change at the species level and at the community level. I will present some of the recent research in this field and contrast it to my research on diversity and compositional changes in Arctic arthropods. Life history traits such as phenology, reproduction and body size have been heavily impacted by climate change. I will present some of the results from recent research in this field and relate changes in life history traits to changes in distributional patterns (i.e. species occurrences). The Arctic is a large heterogeneous biome, and some of the results may therefor only be applicable in a narrow geographic context. I have attempted to distinguish between the patterns that can be generalized into an overall Arctic context and the patterns that are unique for Greenland. Finally, I round up the synopsis with a conclusion and finishing comments of future recommendations based on the findings of my PhD. LIST OF PAPERS PAPER I: Hansen RR, Hansen OLP, Bowden JJ, Normand S, Bay C, Sørensen JG, and Høye TT. 2016a. High spatial variation in terrestrial arthropod species diversity and composition near the Greenland ice cap. Polar Biology:1-10 DOI: 10.1007/s00300-016-1893-2. PAPER II: Hansen RR, Hansen OLP, Bowden JJ, Treier UA, Normand S, and Høye TT. 2016b. Meter scale variation in shrub dominance and soil moisture structure Arctic arthropod communities. Peerj 4:e2224 DOI: 10.7717/peerj.2224. PAPER III: Hansen OLP, Hansen RR, Bowden JJ, Normand S, Treier U and Høye TT. In prep. Diversity and composition changes along a continentality gradient in the Arctic. BMC Ecology. PAPER IV: Hansen RR, Asmus A, Bowden JJ, Loboda S, Iler AM, CaraDonna PJ, Hansen OLP, Normand S, Loonen MJJE, Schmidt NM, Aastrup P and Høye TT. In prep. Synchronous seasonal dynamics in composition, richness and turnover of arthropod assemblages across the Arctic. Ecography. PAPER V: Bowden JJ, Hansen RR, Olsen K, and Høye TT. 2015b. Habitat-specific effects of climate change on a low-mobility Arctic spider species. Polar Biology 38:559-568 DOI: 10.1007/s00300-014-1622-7. PAPER VI: Bowden JJ, Eskildsen A, Hansen RR, Olsen K, Kurle CM, and Høye TT. 2015a. High-Arctic butterflies become smaller with rising temperatures. Biology Letters 11 DOI: 10.1098/rsbl.2015.0574. PAPER VII: Høye TT, Eskildsen A, Hansen RR, Bowden JJ, Schmidt NM, and Kissling WD. 2014. Phenology of high-arctic butterflies and their floral resources: Species-specific responses to climate change. Current Zoology 60:243-251 ACKNOWLEDGEMENTS The past three years work, now culminating with the production of this thesis, has been exciting, but also challenging years and I could not have achieved this without the support of family, friends and colleagues. Some of the challenges, I had help overcoming with tremendous support from my supervisor Toke Thomas Høye and co-supervisor Signe Normand. Both offered me sound scientific guidance during all phases of my PhD, and helped me to understand all aspects of the publication process. I would particularly like to thank Toke Thomas Høye for enthusiastically believing in my results, and encouraging me to pursue my goals. I am grateful to both for showing me that pursuing a scientific career does not need to come at the expense of family, but that career and family can act in concert and strengthen the outcome in the end. My colleagues both at Kalø and Arctic Research Center as well as colleagues visiting from abroad, have made the years fly bye, not only by offering scientific sparring at a qualified and interdisciplinary level, but particularly by adding pleasant company to the journey. I kindly thank the Arctic Research Center for providing funding and housing throughout the full course of my PhD. I would also like to thank the Natural History Museum in Aarhus, who harbored me during the sorting and identification process and provided materials, room and enjoyable company. I owe very special gratitude to my son Daq Lindhardt Reisner who has endured my absence, short holidays and parental mood swings with a smile and an amazing attitude. This could not have gone as smoothly without the help of my mom Karin Bursche Leth and the Busk- Veje family, who all have provided my son with a second home, in my absence. Finally, I would like to thank my partner Lars Nygaard Nielsen for bearing with me in the final stages and showing me unconditional encouragement and loving support. Rikke Reisner Hansen August 2016 SUMMARY With this thesis I provide new insight into how climate change can be expected to affect different aspects of future arthropod diversity (i.e. composition, diversity and life history traits), through the deciphering of past and contemporary distribution patterns. I identify important drivers of local and regional variation in community and population differences of Arctic terrestrial arthropods. The focus is primarily on Greenland, yet the results are discussed in a wider geographical context. We show that Arctic arthropod assemblages varies over very short distances and that patterns in composition and diversity are dictated by local to landscape scale habitat features (Paper I and II). Large geographical features, such as fjords, glaciers and mountain ranges fragments species pools and creates distinct site specific arthropod communities (Paper I, II and III). These findings are in sharp contrast to the conception of the Arctic as a species poor and homogenous environment. While heterogeneity of the habitat sampled and the overall size of the study area are variables shown