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We reconstructed vegetation, fire and watershed history during the Late Roman-Early Middle Ages and in the last three centuries in a mixed conifer forest forming the middle mountain elevational belt in the inner Alpine region, analyzing co-registered micro-botanical data, charcoal particles, sediment lithology, nutrients, and modern pollen deposition from a high-resolution peat record in Valmalenco (Italian Alps). During Late Roman Age the site hosted a dump mixed conifer forest dominated by Picea abies and Abies alba on peaty forest soil, locally affected by fires which also triggered episodes of hillslope denudation. Fire frequency increases during Early Middle Ages dry and warm phases, favoring Alnus viridis and Larix, while Abies alba and Alnus glutinosa type maintained a main role in the pre- and post-fire. Specifically, Abies alba, nowadays eradicated from the Valmalenco watershed, withstood the local regime of low intensity surface fires for more than a millennium, from the Late Roman throughout the Early Middle Ages. Larix, Alnus viridis and Fraxinus excelsior abundance in modern vegetation is ascribed to effects of intensified disturbance in the Early Modern Age, and to further woodland thickening triggered by fire suppression and abandonment after the Second World War.

In this paper, we describe a 5500-year long core obtained from a lake in the Prealps of northern Italy to investigate the impact of human communities on the lacustrine environment. Specifically, we report micro-botanical proxies (upland and aquatic pollen, algae, cyanobacteria, dung spores, microcharcoal particles), sedimentary parameters (LOI steps, calcimetry, FTIR spectra) and nutrients (P forms, C/N and K) on paired samples in a high-resolution stratigraphy, dated by 14C AMS dating and tie point correlation. Independent archaeological evidence indicates the existence of lakeside settlements and farming in Bronze Age times from c. 4000 to 3300 cal yrs. BP. The impact of this Bronze Age village is recorded by an accumulation of plant detritus, pollen, charcoal and abundant wood and bone-derived ash. Intensive P mineralization by ash production was accompanied by the rapid burial of Pinorg, K, and microcharcoal. Correlated peaks of Porg and pasture plant pollen mark the contribution of animal husbandry to Porg lake sink. The nutrient flux produced by external catchment cropping contrasts with the internal flux discharged by prehistoric dwelling and in turn distinguishes domestic hearth production from a contribution by animal husbandry. Forest conditions and lake sedimentation returned to semi-natural baseline at the end of this 700-year long phase of Early to Middle Bronze Age settlement, but pollen proxies indicate that lake-side forests did not fully recover. Lake Lucone represents a key site, since it documents interactions between bronze Age settlements and related ecological impacts on both terrestrial environment and lacustrine sedimentation, as recorded in a continuous sequence, as well as the end of Bronze Age pile dwelling culture.

Sedimentary archives at or near the timberline ecotone in Alpine glaciated areas contain records to study Holocene climate change and the interplay between climate, ecosystems, and humans. We focused on records of timberline and glacier oscillations in the Rutor Glacier forefield (Western Italian Alps) in the last 8800 years. Human activity in this area was negligible for most of the Holocene. We adopted an integrative stratigraphic approach including proxies for glacier advance and timberline estimation, sedimentary events, and reconstructed temperatures. Changes in timberline ecotone correlate to climate until the Middle Ages. Pollen-stratigraphic evidence of a primary plant succession highlights a lag beween local deglaciation and the first reliable 14C age. The radiocarbon chronology points to a prolonged phase of glacier contraction between 8.8 and 3.7 ka cal BP. Even later the glacier remained within its LIA limits. Between 8.4 and 4 ka cal BP MAT-inferred TJuly fluctuated near 12.4 °C, ca. 3.1 °C higher than today. During this period, a Pinus cembra forest belt grew at 2600 m asl with an upper limit of tree groves placed 434 ± 310 m above the current open forest limit. This Holocene phase of thermal maximum ended between 3.98 and 3.51 ± 70 ka cal BP and with a substantial rearrangement of forest composition; temperature reconstruction shows a decrease of 1.8 °C. This climate deterioration concluded the Subboreal thermal optimum, mirroring glacial advances widely documented in the Alps. The Rutor Glacier advanced at ca. AD 1093 ± 65, and remained inside the LIA maximum extent. The LIA started since AD 1594, and culminated between AD 1751 and 1864.

The southern Alpine foreland, facing windward to moist southern airmasses, is claimed to have supported forest vegetation throughout the Last Glaciation. Here we present a multiproxy paleoecological record from a compressed peat, uncovered at Casaletto Ceredano, N-Italy, spanning the interval from 33 to 30.5 kyr cal BP. Stratigraphically, it underlies a fluvioglacial belt attributed to the Last Glacial Maximum. The peat records a floodplain swamp community with tree birch and tall sedges, pine woodlands in upland areas, and only limited patches of open vegetation. Plant macrofossils – bark, charcoal, wood and fruits – establish the predominant role of Betula pubescens group (downy birch) in the anoxic wetland, thanks to its ability to enhance gas exchange through a distinctive type of bark lenticels. A fire-induced birch-to-pine cycle is repeated twice along the 2500 years-time span covered by the peat layer. The climate reconstructed from modern pollen analogs compares to northern boreal zone, with Tjuly < 15 °C, excluding warm-temperate trees. A major flood sealing the swamp with minerogenic silt is precisely dated to 30,497 ± 594 yr cal BP (2σ uncertainty). Here, the pollen record shows a substantial forest withdrawal, and development of grasslands and semideserts, pointing to co-factorial action of increased climate continentality and of river dynamics. According to teleconnections with the Atlantic and Arctic framework of the stadial–interstadial climate variability, the age and pattern of this event are consistent with the onset of Heinrich Stadial 3, causing a lockdown of moist westerlies and of their Rossby waves in the W-Mediterranean.

The Pleistocene history of climate control on sedimentation in the Southern Alps-Po Plain system, northern Italy, was reconstructed using an integrated magnetostratigraphic, palynological, and petrographical approach on a 47-m-deep core. The core mainly consists of lacustrine sediments pertaining to the Bagaggera sequence, deposited at the foothills of the Southern Alps during the late Matuyama subchron (0.99-0.78 Ma). At that time, climate worsened globally and locally it caused the progradation of an alluvial fan unit onto the nearby Po Plain, triggering lake formation by damming of a tributary valley. These new data are used in conjunction with data from the literature to highlight and track the effects of climate forcing on sedimentation during the late Matuyama subchron in different orographic and geodynamic settings of the Southern Alps-Po Plain system as part of the greater Alpine area. We found that the episodes of alluvial fan and braidplain progradation observed in the southern foreland of the Alps during the late Matuyama global cooling seem broadly synchronous with the deposition of most of the so-called Günz and Älterer Deckenschotter deposits in the northern forelands of the Alps as well as with the first major waxing of the Alpine valley glaciers, possibly around the Marine Isotope Stage 22 (∼0.87 Ma). © 2009 Elsevier Ltd. All rights reserved.