Plant-human interactions: from pristine forest to Bronze Age farming—vegetation history and depositional processes off-shore the lake dwelling of Lavagnone, N-Italy

Here, we present a comparative analysis of micro- and macrobotanical remains deposition in the small, shallow lake Lavagnone, which hosted a long-lasting Bronze Age pile dwelling in the southern Alpine foothills. We obtained a narrative of the vegetation history and a framework for plant depositional processes by compositional changes of micro/macro assemblages, co-registered off-shore, near to a lake dwelling site, naturally accumulated in a stable water column reached by domestic dumps. Data analysis has been supported by ecological grouping and multivariate ordination. The record spans the time of pristine forest surrounding the lake prior to the pile dwelling foundation (5530–2080 cal bc), a dramatic biodiversity reversal at the settlement foundation, and the subsequent development of farming and animal husbandry, recorded by an expansion of dry arable fields and pasture vegetation (2080–1470 cal bc). This long-term trend is likely the product of decreased soil water balance due to erosion of alfisol argillic horizons by overgrazing and hillslope ploughing. The near-site dynamic of plant deposition during the settlement phase consists of several episodes of dumping plant debris and faeces from dwelling in alternating layers with still natural, aquatic assemblages. Dump microfossils are predominantly represented by pollen and domestic charcoal, while macrofossils (seeds/fruits and macrocharcoal) mainly consist of food refuse, crop processing by-products, kitchen waste, cleaning remains of fireplaces, decayed faeces, etc. thrown directly into the water from the stilt houses and dispersed on the bottom of the lake.