A first assessment of the main climatic drivers that modulate the tree-ring width (RW) and maximum latewood density (MXD) along the Italian Peninsula and northeastern Sicily was performed using 27 forest sites, which include conifers (RW and MXD) and broadleaves (only RW). Tree-ring data were compared using the correlation analysis of the monthly and seasonal variables of temperature, precipitation and standardized precipitation index (SPI, used to characterize meteorological droughts) against each species-specific site chronology and against the highly sensitive to climate (HSTC) chronologies (based on selected indexed individual series). We find that climate signals in conifer MXD are stronger and more stable over time than those in conifer and broadleaf RW. In particular, conifer MXD variability is directly influenced by the late summer (August, September) temperature and is inversely influenced by the summer precipitation and droughts (SPI at a timescale of 3 months). The MXD sensitivity to August–September (AS) temperature and to summer drought is mainly driven by the latitudinal gradient of summer precipitation amounts, with sites in the northern Apennines showing stronger climate signals than sites in the south. Conifer RW is influenced by the temperature and drought of the previous summer, whereas broadleaf RW is more influenced by summer precipitation and drought of the current growing season. The reconstruction of the late summer temperatures for the Italian Peninsula for the past 300 years, based on the HSTC chronology of conifer MXD, shows a stable model performance that underlines periods of climatic cooling (and likely also wetter conditions) in 1699, 1740, 1814, 1914 and 1938, and follows well the variability of the instrumental record and of other tree-ring-based reconstructions in the region. Considering a 20-year low-pass-filtered series, the reconstructed temperature record consistently deviates < 1 °C from the instrumental record. This divergence may also be due to the precipitation patterns and drought stresses that influence the tree-ring MXD at our study sites. The reconstructed late summer temperature variability is also linked to summer drought conditions and it is valid for the west–east oriented region including Sardinia, Sicily, the Italian Peninsula and the western Balkan area along the Adriatic coast.

An integrated approach including dendrometric and dendrogeomorphological analysis, geotechnical monitoring and numerical modeling was established on a reactivating landslide in a forested Deep-Seated Gravitational Slope Deformation (DSGSD) area in Valtellina, Italy, in order to define the distribution of surface displacements in space and time as well as to identify the triggering factors (i.e. precipitation and a recent road tunneling). By means of a normalized difference eccentricity index (EI), we dated with annual resolution the surface displacements occurred over the period 1980–2016: the instability signals spread from the upper portion of the landslide (C) in 1980s to the middle section (B) especially in the 2000s, when they also occurred in the lowest portion (A). Mean Absolute EI (MAEI index) highlighted the intensity of the displacement signals, whereas changes in the MAEI series (dMAEI index) allowed to find correspondences between precipitation input and tree-ring eccentricity. A diagnostic test applied to these correspondences showed an overall accuracy of 0.74 and allowed to determine the precipitation threshold values acting as triggering factors. Topographic monitoring networks in 2016 revealed displacements <1 mm in the upper portion of the landslide, whereas the middle and lowest portion displacements were ranging 1–10 mm. The inclinometric probes confirmed the same trend for in-depth displacements, pointing out multiple sliding surfaces. A numerical stress-strain model, integrating information both from the instrumental and the dendrochronological approaches, provided information on the slope dynamics and its controlling factors, including groundwater flow conditions and the recent tunneling, thus allowing a comprehensive assessment of the geomorphological hazard.

Landslides inventories are crucial documents for extrapolating the spatial distribution of landslides that occurred in the past. However, the production of landslide hazards maps also needs deepening the knowledge on the temporal distribution of landslide activity. In this regard, historical maps and archive documents represent important sources of data and information on territory evolution through time and especially on landslides occurrence. Nevertheless, these kinds of data sources are rarely considered as they often must be interpreted integrating different disciplines. This work shows how historical and geomorphological data on landslides occurrence in an area of the Northern Apennines can be integrated to produce a synthesis map. This synthesis map put together analogic and digital information allowing to delineate the landscape evolution, in terms of spatial and especially temporal changes occurred in the study area representing a tool that could be useful for the landslide hazard assessment in territory management.

The tree-ring stable carbon and oxygen isotope chronologies from two forest sites located in the Forni Glacier forefield (Italy)—one along the glacier stream (GL) and the other toward the valley slope (SL)—were analyzed with the aim of disentangling the precipitation and glacier meltwater inputs in source water δ¹⁸O, as reflected by the tree-ring cellulose δ¹⁸O. The cellulose δ¹⁸O from the GL trees has a negative correlation with winter and summer temperatures, whereas the cellulose δ¹⁸O from the SL trees has a positive correlation with precipitation δ¹⁸O. The isotopic signature of the source water at the GL site is also influenced by waters of glacial origin, as confirmed by the ¹⁸O-depleted glacier meltwater inputs (GMWI_δ¹⁸O) estimated by means of an isotope model. The GMWI_δ¹⁸O values are consistent with the mean difference measured between the δ¹⁸O in the glacier stream and in the precipitation and the winter and summer temperature explains up to 37 percent of the GMWI_δ¹⁸O variance. Our results show an increasing influence of glacier meltwater throughout the past decade for the GL site. Our analysis opens new opportunities to reconstruct changes in water regimes of the glacier streams by means of the tree-ring cellulose δ¹⁸O.

The distribution of small water bodies associated to landslides in a part of the Northern Apennines (Italy) has been explored, for the first time, using GIS analysis, field surveys and geophysical imaging. The analysis on the whole investigated area was performed using the Topographic Wetness Index (TWI), a proxy for surface soil moisture patterns based on topographic characteristics. The case studies correspond to two large landslides deep-rooted in the bedrock. The Sauna landslide in the Parma torrent basin and the Berceto landslide in the Taro river basin, have been investigated through field work, geophysics, boreholes and radiocarbon dating for the time constraints of the water bodies. The TWI analysis carried out both at the regional and the case-study scale has shown that low values of this index (drier areas) are more associated with inactive landslides portions, whereas higher values (wetter areas) are more associated with active portions. The analyses on the case studies highlighted that the condition characterized by wet soil and/or the presence of small water bodies are spatially persistent across time in correspondence of the same portion of the landslide that preserves landforms able to maintain these waters. As highlighted by geophysics, these landforms are in connection with deep shapes of the sliding/rupture surface of the landslide that mimic those at the surface.

The expansion of glacier‐free forelands after glacier retreat is emerging as a typical climate change‐dependent feature that is widely studied for assessing biogeomorphic feedbacks and analysing the vertical processes and changes occurring in the critical zone (CZ). However, the horizontal processes occurring in the CZ environment are still poorly understood. Here, we comprehensively analyse the development of the CZ environment over time in the Forni Glacier forefield, Italian Alps, since the end of the Little Ice Age (LIA) by considering different sectors (air, forest, water and soil) in two portions of the glacier forefield: the lower portion, which occurs below the glacier‐forefield treeline (GFT), where a fully functioning CZ environment has developed, and the upper portion, which occurs above the GFT, in the proglacial area (PA), where only an incipient CZ exists. The early stages of CZ development in the PA are highly influenced by katabatic winds, which impact the colonisation patterns of saplings and young trees, and characterised by high‐energy geomorphic processes that cause sediment reworking and initial stages of soil development. Below the GFT, the minimum tree ecesis interval after glacier retreat reaches a median value of 38 years (n = 8), and the fully developed CZ environment (with trees reaching at least 2 m in height after 20 years) formed after ~60 years following glacier retreat and is characterised by forest cover, soils organised in a chronosequence and contrasting isotopic signatures of surface and running waters. The correlation with the isotopic signatures of tree rings allowed us to estimate a groundwater flow period of approximately 2 months from the slopes into the CZ of the valley floor. By analysing the horizontal processes driving the geomorphic and biotic evolution patterns of a glacier forefield, this work introduces a novel approach for assessing the development of the CZ environment over time.