Pastoralism and mining activities affecting timberline ecosystems in the Italian Alps during the last millennia

Abstract

Historical ecology and palaeoecology provide a key for understanding the last millennia’s landscape changes, by reconstructing the chain of ecological/anthropogenic events that generated the current dynamics of the living systems. We analysed co-registered bio- and geoecological proxies (micro-botanical data, charcoal fragments, elemental abundance, nutrients), retrieved from a subalpine mire in Valmalenco, Italian Alps, to infer the main environmental transformations that led to the current larch-parkland-pasture landscape typical of timberline elevations in the Alps. The radiocarbon-dated record begins ca. BC 1300 with a primary forest formed by Pinus cembra, Picea excelsa and Larix decidua already affected by anthropogenic disturbance. Human impact increases during Early Iron Age with the development of mining activities and pastoralism. Local fires occurred in the Iron-Roman Ages; but from AD 1035, the primary forest experiences a definitive collapse to clear space for pastures during a climatically favourable phase. Lead enrichment unravels smelting activities that contributed to century-scale human impact increase. Critical minerogenic intake in Spundascia’s mire are related to the severe environmental conditions established during the Little Ice Age. In the Modern Age, pasture is carried even within the mire, as indicated by abundance of spores of coprophilous fungi. In conclusion, it is the last millennium of mostly anthropogenic drivers, enhanced by positive climate feedback, which overturned the ecological trajectories towards the modern setting of pasture intensity, eutrophication and fire disturbance.