Christian-Albrechts-Universität zu Kiel Graduate School “Human Development in Landscapes” CRC 1266: “Scales of Transformation - Human-Environmental Interaction in Prehistoric and Archaic Societies” Human-environment dynamics across the Bronze Age in northern Italy: method testing and multi-proxy approaches Dissertation in fulfilment of the requirements for the degree of “Dr. rer. nat.” of the Faculty of Mathematics and Natural Sciences at Kiel University submitted by Marco Zanon Kiel, 2020 First referee: Prof. Dr. Wiebke Kirleis Second referee: Prof. Dr. Ingmar Unkel Date of oral examination: March 23, 2020 Table of Contents Page Sworn declaration v Abstract vi Zusammenfassung vii List of Figures viii List of Tables xv Part I 1 Setting the frame: The Bronze Age lake-dwelling phenomenon in northern Italy 1 Tackling socio-environmental triggers: ongoing hypothesis and data availability 5 Research rationale and structure of this PhD thesis 8 Bibliography 12 Part II 17 Environmental conditions towards the onset of the Bronze Age pile-dwelling 17 phenomenon Palaeoenvironmental dynamics at the southern Alpine foothills between the Neolithic and the Bronze Age onset. A multi-proxy study from Bande di 19 Cavriana (Mantua, Italy) Abstract 19 Introduction 20 Study site: Bande di Cavriana 22 Materials and methods 23 Corings and stratigraphy 23 Sample selection 25 Geochemical analysis 25 Loss on ignition 25 X-ray fluorescence (XRF) 26 Carbon/nitrogen ratio 26 Stable isotopes 26 Pollen analysis 27 i Temperature modeling 27 Radiocarbon dating and age-depth modeling 28 Results and interpretation 28 Sediment geochemistry 28 LOI 28 XRF 29 Carbon-nitrogen ratio 32 Stable oxygen and carbon isotopes 33 Pollen record 33 Chronological assessment 35 Temperature reconstructions 39 Discussion 39 Notable climatic events 39 Land cover changes 43 Pre-Bronze Age woodland dynamics: the expansion of Carpinus betulus 43 Transition into the Bronze Age 46 Conclusions 48 Acknowledgements 49 Bibliography 50 Part III 59 Population collapse and climate dynamics at the end of the Bronze Age 59 Highly diverse Bronze Age population dynamics in Central-Southern Europe 61 and their response to regional climatic patterns Abstract 61 Introduction 62 Materials and methods 64 Demographic reconstructions 64 Climatic reconstructions 69 Results 73 Swiss plateau 75 Po plain 80 Massif central 83 NW-Mediterranean 85 Discussion 85 Conclusions 91 Acknowledgments 92 Bibliography 93 ii Part IV 105 Land cover modeling: from qualitative pollen data to quantitative forest cover 105 percentages European Forest Cover During the Past 12000 Years: A Palynological 107 Reconstruction Based on Modern Analogs and Remote Sensing Abstract 107 Introduction 108 Materials and methods 111 Fossil and modern pollen data 111 Remote sensing data 112 Definition of forest cover 114 Quality filtering 116 Past forest-cover reconstruction 117 Mapping procedure 118 Evaluation of the reconstruction method 120 Performance of the transfer function and interpolation using modern data 120 Reconstruction of Holocene forest cover in the Alps 120 Comparison between MAT and REVEALS estimates of past forest cover 121 Results 123 Model validation 123 Performance of the cross-validation exercise 123 MAT–REVEALS comparison 123 Quantification of no-analog occurrences 125 Bias correction 127 Evaluation of the interpolation procedure 129 Forest-Cover elevation in the Alpine environment 131 Forest-cover reconstructions 131 Late Pleistocene and Holocene onset (Figs. 4.10, 4.12a-b) 131 First half of the Holocene (Figs. 4.10, 4.12c–g) 131 Second half of the Holocene (Figs. 4.10, 4.12h–l) 133 Discussion 133 Sources of uncertainty 133 No-analog situations and the PFT approach 139 Forest-cover underestimation 140 Comparison with current land-cover change narratives 141 Late Pleistocene 141 Post-glacial forest recovery 142 Middle/Late Holocene forest cover decline 143 Vertical performance of the interpolation procedure in the Alpine region 145 Conclusion 146 Funding 148 iii Acknowledgments 148 Bibliography 149 Part V 165 Human-environment dynamics between Middle and Late Holocene: an overview 165 of the results Unraveling climate trajectories 165 Investigating land cover and land use changes 170 Bibliography 175 Appendix I 177 Grezze 178 Polecra Pond 180 Ca’ Nove 182 Lake Frassino 185 Bibliography 188 Appendix II 189 Appendix III 190 Bibliography 217 iv Sworn declaration I hereby confirm that the following statements are true and correct: - apart from the supervisor's guidance, the content and design of the thesis are solely a product of Marco Zanon’s own work, - this thesis has not been previously submitted, either partially or as a whole, to another examining body as part of a different doctoral project. Sections of this thesis have been published in peer-reviewed journals in fulfillment of the requirements for the production of a cumulative dissertation. These already- published sections are clearly identified as such in the body of the dissertation, - this production of this thesis was conducted in accordance to the Rules of Good Scientific Practice of the German Research Foundation, - Marco Zanon never incurred in the withdrawal of any academic degree. v Abstract Besides technological innovations and new typological features, the transition into the Bronze Age in northern Italy is marked by the adoption of distinctive settlement strategies. Prominent differences with previous periods are represented not only by higher numbers and density of settlements, but also by a widespread preference for wetland areas. These phenomena are particularly evident in the Lake Garda region, where a rising number of lacustrine pile-dwelling settlements is documented since the Bronze Age onset (approximately 4150 years cal. BP). The pile-dwelling phenomenon lasted approximately for one millennium, approximately until 3150 years cal. BP). At the end of the Late Bronze Age, this settlement system collapsed, leaving the area largely depopulated. Widespread settlement abandonment did not affect only the surroundings of Lake Garda. In the neighboring central Po Plain, a dense network of riverine villages developed since approximately 3500 years cal. BP. These moat-and-rampart villages, locally termed “terramare”, abruptly disappeared together with the last pile dwellings. The reasons behind the rise and demise of these extensive lacustrine and riverine settlement networks remain currently open for discussion. Palaeoecological studies conducted in the area focused mostly on developing qualitative land- use narratives for the Bronze Age. As a result, multiple questions remain to be addressed concerning the determination of local climate trajectories. Similarly, quantitative land-cover approaches are left largely unexplored. Given these premises, this project aims at improving the available knowledge concerning both the role of climate and land use dynamics in northern Italy across the Bronze Age and neighboring periods, with a special focus on the pile-dwelling phenomenon in the southern Lake Garda region. The results are presented in the form of a cumulative dissertation composed of three published papers. The first of these three contributions focuses on the sedimentary record of Bande di Cavriana, a drained wetland in the Lake Garda area. Here, palynological and geochemical analysis provided new evidences that the rise of the Bronze Age pile-dwelling phenomenon occurred under a rapidly changing climate. The second paper focuses on the collapse of Bronze Age settlement networks. Pollen-based temperature and precipitation models obtained from Northern Italian sites depict increasingly arid conditions towards the end of the Bronze Age. This reconstruction is in agreement with the current archaeological narrative, which attributes the end of the central Po Plain settlement networks to a combination of landscape overexploitation and to the emergence of unsuitable climatic conditions. The third contribution serves primarily a methodological role within this project. It provided the opportunity to test extensively a landscape reconstruction algorithm based on pollen data and remote sensing. The application of this method to pollen sequences from Lake Garda provided a very first quantitative reconstruction of land cover changes across the Copper Age- Bronze Age transition, in connection with the establishment of the first pile-dwelling settlements. vi Zusammenfassung In Norditalien ist der Übergang in die Bronzezeit neben technologischen Innovationen und neuen typologischen Merkmalen durch die Einführung veränderter Siedlungsstrategien gekennzeichnet. Auffällige Unterschiede zu früheren Perioden zeigen sich nicht nur in einer erhöhten Anzahl und Dichte der Siedlungen, sondern auch durch eine weit verbreitete Präferenz für Feuchtgebiete. Besonders deutlich werden diese Phänomene in der Region des Gardasees, wo seit Beginn der Bronzezeit (ca. 4150 Jahre cal. BP) zunehmend Pfahlbausiedlungen an Seeufern dokumentiert sind. Das Pfahlbauphänomen dauerte etwa ein Jahrtausend, bis 3150 Jahre cal. BP). Am Ende der späten Bronzezeit brach dieses Siedlungssystem zusammen, so dass das Gebiet weitgehend entvölkert blieb. Die weit verbreitete Siedlungsaufgabe betraf nicht nur die Umgebung des Gardasees. In der benachbarten zentralen Po-Ebene entstand seit etwa 3500 Jahren cal? BP ein dichtes Netz von an Flussufern gelegenen Dörfern. Diese mit Wassergraben und Wall eingefassten Dörfer, bekannt als "Terramare", verschwanden abrupt zusammen mit den letzten Pfahlbauten