Holocene vegetation and land-use changes in response to climatic changes in the forelands of the southwestern Alps, Italy

The Holocene sediment of Lago Piccolo di Avigliana (Piedmont, Italy, 356 m a.s.l.) was dated by C-14 and analysed for pollen to reconstruct the vegetation history of the area. The early- and mid-Holocene pollen record shows environmental responses to centennial-scale climatic changes as evidenced by independent palaeoclimatic proxies. When human impact was low or negligible, continental mixed-oak forests decreased at ca. 9300 BC in response to the early-Holocene Preboreal climatic oscillation. Abies alba expanded in two phases, probably in response to higher moisture availability at ca. 6000 and ca. 4000 BC, while Fagus expanded later, possibly in response to a climatic change at 3300 BC. During and after the Bronze Age five distinct phases of intensified land use were detected. The near synchroneity with the land-Use phases detected in wetter regions in northern and southern Switzerland points to a common forcing factor in spite Of Cultural differences. Increasing minerogenic input to the lake since 1000 BC coincided with Late Bronze-Iron Age technical innovations and probably indicate soil erosion as a consequence of deforestation in the lake catchment. The highest values for cultural indicators Occurred at 700-450 and at 300-50 Bc, coinciding with periods of high solar activity (inferred from Delta C-14). This suggests that Iron Age land use was enhanced by high solar activity, while re-occupation of partly abandoned areas after crises in earlier periods match better with the GRIP stable isotope record. On the basis Of Our data and comparison with independent palaeoclimatic proxies we Suggest that precipitation variation was Much more important than temperature oscillations in driving vegetation and societal changes throughout the Holocene. Copyright (c) 2006 John Wiley & Sons, Ltd.