Durham E-Theses Climate, Vegetation and the Complex History of Pinus sylvestris during the Holocene, in Wester Ross, Northwest Scotland. NICHOLSON, HEATHER How to cite: NICHOLSON, HEATHER (2015) Climate, Vegetation and the Complex History of Pinus sylvestris during the Holocene, in Wester Ross, Northwest Scotland., Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/11304/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk 2 Climate, Vegetation and the Complex History of Pinus sylvestris during the Holocene, in Wester Ross, Northwest Scotland. Heather Nicholson Masters by Research Department of Geography at 2014 i Abstract The close proximity of the North Atlantic to Wester Ross makes the vegetational, climatological and anthropogenic history of the region particularly interesting. This study aims to reconstruct these three aspects of the Holocene from peat deposits at Meall Bad á Chrotha. Such studies are vital if we are to improve our understanding of current climate change and prepare for the future implications it may cause. The warming climate of the Lateglacial and early Holocene saw the terrestrialisation of the lake which occupied the site and subsequent establishment of mixed Betula/Corylus woodland. The continued rise in summer temperatures led to the Mid-Holocene Thermal Maximum and the associated replacement of mixed woodland by Pinus sylvestris. It is likely that dense pine forest occupied the area by 7000 cal BP, encouraged by the drier conditions and possibly the occasional, small- scale wild or domestic fire. The lack of evidence for Mesolithic-Neolithic activity within the record is fairly unsurprising due to the high altitude and exposed nature of the site; however, there is evidence for early activity elsewhere on the South Erradale Peninsula. The ‘Mid-Holocene Pine Decline’ is a distinctive part of the vegetational history of Meall Bad á Chrotha most probably occurring in response to a substantial reduction in summer temperatures. This climatic deterioration known as the ‘Holocene Thermal Decline’ and subsequent wet shift can be linked to an ice rafted debris event which occurred in the North Atlantic around 4200 years ago (Bond et al, 1997). Minor rises in Plantago lanceolata and charcoal from the mid-late Holocene most likely represent the intensification of land use in the valley below as communities exploited the newly open landscape, and were perhaps responsible for the continued fall in arboreal pollen. The temperature continues to fall below early Holocene values with a rise in water-tolerant communities and peat-forming conditions towards present day. ii Table of Contents Title Page…………………………………………………………………………………………….…..........…i Abstract……………………………………………………………………………………………………………..ii Table of Contents……………………………………………………………………………………………….iii List of Tables………………………………………………………………………………………………….…vii List of Figures……………………………………………………………………………………………………viii Abbreviations……………………………………………………………………………………..…….……..xiii Statement of Copyright…………………………………………………………………………………….xiv Acknowledgments………………………………………………………………………………………….…xv Chapter 1: Introduction……………………………………………………………………..1 1.1 The Importance of Reconstructing Past Environments and Holocene Climate Research……………………………………………………………………………………...…1 1.2 Introduction of Pollen Analysis and the Principles of Palynology……………5 1.3 Research Questions, Aims and Objectives…………..…………………………………6 Chapter 2: Literature Review……………………………………………….……………8 2.1 The Late Devensian (Lateglacial) in Scotland………………………………..……...8 2.1.1 The Wester Ross Re-advance…………………………………………………8 2.1.2 The Windermere Interstadial (Bølling-Allerød) (15,000 – 13,000 cal BP)…………………………………………………… ………………………….………….11 2.1.3 The Loch Lomond Stadial (Younger Dryas) and Lateglacial Holocene Transition (13,000 – 11,700 cal BP)……………… ……………….12 iii 2.1.4 Anthropogenic Activities during the Upper Palaeolithic and Evidence for Ahrensburgian Technology………………………………………..12 2.2 The early Holocene in Scotland (11,700-6000 cal BP)…………………………..15 2.2.1 Vegetation and Climate………………………………………………………...15 2.2.2 The Origins of Pinus sylvestris in Northwest Scotland……………20 2.2.3 The Mesolithic………………………………………………………………………26 2.2.3.1 The Mesolithic to Neolithic Transition…………………….27 2.2.3.1.1 The Immigration Model……………………………29 2.2.3.1.2 The Neolithization Model…………………………30 2.3 The Mid-Late Holocene in Scotland (6,000 cal BP – Present)……………….32 2.3.1 Vegetation and Climate…………………………………………………………32 2.3.2 Late Bronze Age Climatic Deterioration and Settlement Stability………………………………………………………………………………………….39 2.4 The Complex History of Pinus sylvestris…………………………………………….…40 2.5 The Effect of Climate Change on the Germination and Growth of Pinus sylvestris……………………………………………………………………………………………………42 2.6 Forcing Mechanisms behind Climate Change…………………………………………………………………………………….………………..44 2.6.1 Ice Rafted Debris Events and Changes in the North Atlantic…………………………………………………………………………………………..44 2.6.2 Solar Variability……………………………………………………………….…….45 2.6.2.1 ∆14C and Solar Activity…………………………………46 2.6.2.2 ∆14C and Cosmic Ray Intensity…………………….49 iv 2.6.2.3 ∆14C and Geomagnetic Field……………………….50 2.6.2.4 ∆14C and the Ocean…………………………………….50 2.6.2.5 Solar forcing of Climate Change………………….51 2.7 Volcanic Activity and the Pine Decline……………………………………………..…52 2.8 Anthropogenic Activity and the Pine Decline……………………………………...57 2.9 Insects and Pathogenic Attack and the Pine Decline…………………………..60 2.10 Mineral deficiency and Pinus sylvestris………………………………………….….61 Chapter 3: Research Area………………………………………………………………..64 3.1 Study Site – Meall Bad á Chrotha…………………………………………………………64 3.2 Current Vegetation ……………………………………………………………………………..65 3.3 Scotland’s Present Forested Regions……………………………………………………65 3.4 Geology and Relief……………………………………………………………………………….68 3.5 Climate………………………………………………………………………………………………..68 3.6 Peatland Distribution…………………………………………………………………………..73 3.7 Peatland Damage…………………………………………………………………………………76 3.8 Human Activity in the Region of Meall Bad á Chrotha…………………………77 Chapter 4: Research Methods………………………………………………………….80 4.1 Study Site and Selection………………………………………………………………………80 4.2 Troels-Smith Classification Scheme (1955)…………………………………………..81 4.3 Sub-Sampling……………………………………………………………………………………….86 4.4 Laboratory Techniques………………………………………………………………………..86 4.5 Analysis and Identification of Samples…………………………………………………87 v 4.6 Charcoal Analysis…………………………………………………………………………………87 4.7 Pollen Percentage Diagram………………………………………………………………….87 4.8 Non-Pollen Palynomorphs……………………………………………………………………88 4.9 Pollen-Climate Transfer Functions…………………………………………………….…89 4.10 Chronology and Dating…………………….………………………………………………..93 4.11 Advantages and Disadvantages of Methodology…………………………..…..94 4.11.1 Advantages …………………………………………………………………………94 4.11.2 Disadvantages……………………………………………………………………..95 Chapter 5: Results……………………………………………………………………..…….97 5.1 Troels-Smith Classification……………………………………………………..……………97 5.2 Pollen and Charcoal…………………………………………………………………….……….99 5.3 MTWA Reconstruction…………………………………………………….…………………114 Chapter 6: Discussion and Interpretation………………………………………118 6.1 Lateglacial to Early Holocene: Pioneer Communities and the Afforestation Period………………………………………………………………………………..118 6.1.2 The Pine Rise……………………………………………………………………….133 6.2 Mid-Holocene: Deforestation and the Pine Decline……………………………139 6.3 Mid-Late Holocene: Return to Open Landscape and Intensification of Anthropogenic Activity…………………………………………………………………………….157 Chapter 7: Conclusion……………………………………………………………………164 Appendix…………………………………………………………………………………………………………168 References……………………………………………………………………………………………………….171 vi List of Tables Table 1 - Lateglacial chronozones and Jessen-Godwin Pollen Zones………….14 Table 2 - Populations of Pinus sylvestris in Scotland analysed for mtDNA variation, and numbers of each RFLP mitotype scored………………………………22 Table 3 - Populations of Pinus sylvestris studied by Soranzo et al (2000)………………………………………………………………………………………………………..24 Table 4 - Haplotypes detected in Pinus sylvestris populations and diversity values………………………………………………………………………………………………………..25 Table 5 - Summary of local palaeohydrological shifts at Eilean Subhainn, Glen Torridon and Glen Carron………………………………………………………………….37 Table 6 - Mid-Holocene major ∆14C rises, their duration and the corresponding wet shifts found in the cores……………………………………………..48 Table 7 - Detailed recordings of climatic conditions and the acid damage reported after the Lake Fissure eruption, AD1783, in Britain and Western Europe...........................................................................................................55 Table 8 - Boundary classification…………………………………………………………….…82 Table 9 - Degree of humification classification…………………………..................83 Table 10 - Degree of darkness classification………………………………………………83 Table 11 - Degree