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Mid-Late Holocene environmental change in northern Sweden: an investigation using fossil insect remains Sara Khorasani Thesis submitted in fulfilment of the degree of Doctor of Philosophy School of GeoSciences The University of Edinburgh September 2013 Declaration The work presented in this thesis is the author‘s own, and, except where specifically stated otherwise, is not based on the published or unpublished work of others. The work has not previously been submitted for any other degree or professional qualification. Signature: Date: Abstract For the first time, Mid-Late Holocene insect fossil assemblages were studied from inland northern Sweden, producing new evidence relating to both natural environmental changes and human impacts. The insect fossil assemblages from natural deposits indicated extensive woodland with old and dead wood and a deep litter layer of decaying matter. Human impacts became apparent from the 1st millennium AD, when the landscape around many sites became more open, with elements of heath. It is difficult to determine whether these changes were driven purely by human activity, indicating subtle landscape change as a result of periodic exploitation, or if natural influences were significant in creating this landscape structure. If connected with human use, then the impacts of periodic exploitation can be seen to be subtle and localised, but notable enough to leave tell- tale signs in the insect fossil record. These relatively subtle changes in the environment can be compared with the more severe effects found during periods of historically known permanent settlement, where extensively open and disturbed habitats are suggested in the insect fossil record. Species associated with arable and pasture land are restricted to the last few hundred years, in association with settled occupation. The climate signal in the insect fossil record has been weak, and use of the Mutual Climatic Range method (MCR) has not revealed evidence of climatic fluctuations during the Late Holocene period. i Acknowledgements This research was funded by the Leverhulme Trust as part of the multidisciplinary project ‗Footsteps on the edge of Thule‘. Thanks go to my main supervisor Eva Panagiotakopulu, who has helped to guide and support me through the process, and to my other supervisors, Ian Ralston and Roger Engelmark, for their input. Further thanks to staff at the University of Umeå, including Phil Buckland for providing the samples taken from the site of Sorsele. Paul Buckland is thanked for his help during fieldwork in northern Sweden. The help and patience of Emma Tetlow and Kim Vickers were extremely valuable in the lab, and their willingness to share their knowledge is much appreciated. Gratitude is extended to Dr Graham Rotheray and Richard Lyszkowski for making great efforts to help me to identify rogue species during consultation of the National Museum of Scotland‘s insect collection. Finally, I would like thank my family, friends and office mates for their ongoing support and encouragement, without which the completion of this thesis would not have been possible. ii Contents 1 Introduction .................................................................................................... 1 1.1 Aims of thesis ................................................................................................ 2 2 The Study Area ............................................................................................... 4 2.1 Terminology ................................................................................................... 4 3 Modern Ecological Setting ............................................................................ 6 3.1 Topography .................................................................................................... 6 3.2 Soils................................................................................................................ 6 3.3 Peatland .......................................................................................................... 6 3.4 Vegetation ...................................................................................................... 8 3.5 Climate ......................................................................................................... 12 3.6 Flora and fauna ............................................................................................ 13 3.6.1 Invertebrates ....................................................................................... 13 3.6.2 Vertebrates ......................................................................................... 15 4 Environmental History of Northern Sweden ............................................. 18 4.1 Natural environmental change ..................................................................... 18 4.2 Vegetation development and climate ........................................................... 22 5 Cultural Setting ............................................................................................ 31 5.1 The archaeological evidence ........................................................................ 31 5.2 Human impacts in the palaeoecological record ........................................... 36 5.2.1 Early evidence for human impacts –hunters and herders .................. 36 5.2.2 Early agriculture ................................................................................. 42 5.2.2.1 South and Central Sweden...................................................... 42 5.2.2.2 Northern Sweden .................................................................... 44 6 Previous Palaeoentomological Work in Scandinavia................................ 49 6.1 The development of palaeoentomology in Scandinavia – an introduction .. 49 6.2 Southern Sweden ......................................................................................... 50 6.3 Northern Sweden ......................................................................................... 54 6.4 Norway ......................................................................................................... 55 6.5 Denmark ....................................................................................................... 57 6.6 Finland ......................................................................................................... 58 7 Methodology ................................................................................................. 60 7.1 Site selection ................................................................................................ 60 7.2 Sampling ...................................................................................................... 61 7.3 Taphonomy and preservation ....................................................................... 62 7.4 Sample processing ....................................................................................... 64 7.4.1 Insects ................................................................................................ 64 7.4.2 Plant macrofossils .............................................................................. 65 7.4.3 Charcoal ............................................................................................. 65 7.5 Radiocarbon dating ...................................................................................... 66 7.6 Interpretation ................................................................................................ 67 iii 7.7 Mutual Climatic Range ................................................................................ 69 7.8 Quantitative analysis .................................................................................... 71 7.8.1 Ecological groupings ......................................................................... 72 7.8.2 Statistical analysis .............................................................................. 72 8 Norrheden ..................................................................................................... 77 8.1 Site description............................................................................................. 77 8.2 Sampling ...................................................................................................... 80 8.3 Dating ........................................................................................................... 82 8.4 Preservation.................................................................................................. 82 8.5 Results .......................................................................................................... 82 8.5.1 Phase I (0-8cm: Samples 2a