Forests, pastures, and furnaces in the south-eastern Alps: the Mid-Late Holocene palaeoenvironmental record of Lake Caldonazzo

Drawing on the Lake Caldonazzo sedimentary record (Valsugana, Italy), this study reconstructs palaeoecological dynamics from the 6th to 1st millennium BCE, revealing the environmental imprint of pre-protohistoric copper mining in the south-eastern Alps. Integrating bio- and geochemical proxies (micro-botanical data, micro-charcoal, faecal biomarkers, and trace elements) we reconstruct the interplay between environmental dynamics and anthropogenic impacts from the Neolithic to the beginning of Iron Age. During the Middle Holocene, pristine silver fir-beech forests dominated the landscape, with incipient Neolithic human influence evidenced by pastoral indicators despite the absence of known settlements in the valley. Copper Age forest decline resulted from climate-induced cooling interacting with agropastoral activity expansion. During the Early and Middle Bronze Age, human impact on mountain ecosystems increased with the integrated development of farming, forest exploitation, and pastoral activities, while early geochemical signals raise the possibility of incipient local metallurgy during the advanced Middle Bronze Age. The Recent-Final Bronze Age marked a metallurgical apex, as evidenced by a surge in the heavy metal enrichment factor and micro-charcoal peaks, corroborating the current archaeological interpretative model. The latter saw the south-eastern Trentino as a continental-scale production hub before environmental degradation and resource depletion marked its end between the 2nd and 1st millennium BCE. Land use reactivation became evident during the subsequent territorial reorganisation of the Early Iron Age. Notably, the Löbben and Göschenen 1 climatic oscillation modulated but did not override anthropic pressures. The study demonstrates that pre-protohistoric communities triggered significant environmental impacts (e.g., deforestation, erosion, heavy metal pollution), underscoring the ecological consequences of resource exploitation within sensitive Alpine ecosystems.