Climate and Land-use Phases around the Alps: A Case Study from Lago Lucone (Northern Italy)
by
Verushka Valsecchi
Laboratory of Palaeobotany and Palynology, University of Utrecht, Budapestlaan 4, NL-3584 CD Utrecht, The Netherlands
Coauthors: Willy Tinner, Institute of Plant Sciences, University of Bern, CH-3013 Bern, Switzerland; André F. Lotter, Laboratory of Palaeobotany and Palynology, University of Utrecht, Budapestlaan 4, NL-3584 CD Utrecht, The Netherlands

In rural societies population and social stability mainly depend on harvest success and thus on favourable climatic conditions. As extensively documented for the past 500 years, the consequence of a series of cold and humid years increased death rates (Maise, 1998; Pfister, 1988; Pfister et al., 1999). Based on these historical observation and on climatic proxies (i.e. residual 14C and glacier oscillations), decreases in archaeological findings in France, Germany and Switzerland at around 800 and 400 BC have been interpreted as climatically driven (Maise, 1998).

In order to address the response of prehistoric societies to climatic change, palaeobotanical anthropogenic indicators of four radiocarbon-dated sediments from Switzerland (Soppensee, Lobsigensee, Lago di Origlio e Lago di Muzzano) were compared to independent climatic proxies (Tinner et al., 2003). Taking into account the dating uncertainties, contemporaneous phase of forest clearances and of intensified land-use at 2100-1900 BC, 1750-1650 BC, 1450-1250 BC, 650-450 BC, 50 BC-100 AD and around 700 AD were detected at all sites (Tinner et al., 2003). These land-use expansions coincided with periods of warm climate as recorded by the Alpine dendroclimatic and Greenland oxygen isotope records. These results suggest that harvest yields have increased synchronously over central and southern Europe during periods of warm and dry climate. In conclusion, these results suggest a high climatic dependence of European prehistorical societies during many millennia (Tinner et al., 2003).

A sediment record retrieved from Lago Lucone (45^° 33¢ N, 10^° 29¢ E, 249 m a.s.l., northern Italy) was used to test this hypothesis. Presence of human populations was attested by pile-dwelling settlements from the Early-Middle Bronze Age ( ~ 2000-1300 BC), with one settlement at only 100 meters distant from the coring site (Bocchio, 1985-1988; Guerreschi, 1980-81; Martinelli, 1996). Pollen and plant-macrofossil analyses were applied to a sediment core of 250 cm, and four dates provide the time control (Valsecchi et al., submitted). Mixed oak forest was cleared during the Early to Middle Holocene and replaced by open vegetation during the Bronze Age ( ~ 2000-1100 BC). Several anthropogenic indicator plants increased during that time, suggesting a strong influence of human activity on the landscape. At the beginning of a phase of high human impact ( ~ 2000 BC), independent climatic proxies, such as Alpine climatic phases (Tinner et al., 2003) and short-term atmospheric 14C variations, indicate a warm and dry climate. Thus, the Early-Bronze Age occupation phase occurred during a favourable climatic period that continued until ~ 1250 BC. Later, archaeological and palaeobotanical evidence indicate a sharp decrease in human pressure in the Lago Lucone area at the transition between the Recent and the Final Bronze Age ( ~ 1100 BC). This decrease was delayed if compared with the extinction of pile-dwelling settlements in the Lago di Garda area (around 1300 BC).

However, this general decline at around 1300-1100 BC is probably synchronous with the end of the pronounced cultural phase at 1450-1250 as documented by other palaeocultural records south and north of the Alps (Soppensee, Lobsigensee, Lago di Muzzano, Lago di Origlio) and the independently inferred end of the correspondent warm-dry phase. However, due to discrepancies between important proxies of past environmental conditions, it is not possible to better assess the role of climate for these societal changes in northeastern Italy. Cultural crises (e.g. wars) or changes in spatial organisation as a forcing factor for declining human impact in the area cannot be ruled out under the present state of knowledge.

References

Bocchio, G., 1985-1988. Saggio stratigrafico presso Lucone D. Polpenazze del Garda (BS). Annalidel Museo Gavardo, 16: 15-43.

Guerreschi, G., 1980-81. La stazione preistorica del Lago Lucone (Brescia)-Scavi 1965-1971. Annali del Museo Gavardo, 14: 7-78.

Maise, C., 1998. Archäoklimatologie - Vom Einfluss nacheiszeitlicher Klimavariabilität in der Ur- und Frühgeschichte. Jahrbuch der Schweizerischen Gesellschaft für Ur- und Frühgeschichte, 81: 197-235.

Martinelli, N., 1996. Datazioni dendrocronologiche per l'Età del Bronzo dell'area alpina. In: K. Ranndsborg (Editor), Absolute chronology: archaeological Europe 2500-500 BC. Acta Archeologica supplementa, 67 (1), Verona.

Pfister, C., 1988. Klimageschichte der Schweiz 1525-1860. Haupt, Bern.

Pfister, C., Brazdil, R., Glaser, R., Barriendos, M., Camuffo, D., Deutsch, M., Dobrovolny, P., Enzi, S., Guidoboni, E., Kotyza, O., Militzer, S., Racz, L., Rodrigo, F.S., 1999. Documentary evidence on climate in sixteenth-century Europe. Climatic Change, 43: 55-110.

Tinner, W., Lotter, A.F., Ammann, B., Conedera, M., Hubschmid, P., van Leeuwen, J.F.N., Wehrli, M., 2003. Climatic change and contemporaneous land-use phases north and south of the Alps 2300 BC to 800 AD. Quaternary Science Reviews, 22: 1447-1460.

Valsecchi, V., Tinner, W., Ammann, B., submitted. Human impact on the vegetation during the Bronze Age at Lago Lucone (northern Italy). Vegetation History and Archaeobotany.

Date received: July 14, 2005

Copyright © 2005 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caqy-31.