NW Italian Alps Research Articles

Faster than expected: 5-year re-surveys reveal accelerating plant colonization in two proglacial forelands of the Gran Paradiso National Park (NW Italian Alps)

Abstract Proglacial vegetation communities are facing major challenges today due to fast glacier retreat and global warming, resulting in possible changes in plant colonization patterns. By re-surveying permanent plots along two alpine chronosequences (encompassing 5 to 165 years from deglaciation) with a 5-year time span, we aimed to (i) assess short-term vegetation changes and (ii) compare current vegetation trajectories with those predicted by the chronosequence approach. We analysed the number and cover of total, pioneer, and alpine grassland species and calculated the slopes of the trajectories of the chronosequence and observed on permanent plots. As expected, the number and cover of total, pioneer, and grassland species increased during the 5 years of the study. Moreover, we observed a significant acceleration in plant colonization (21 and 45 times faster increase in species richness and cover, respectively) compared to the chronosequence predictions. These dramatic changes in vegetation dynamics of proglacial plant communities were probably induced by the increased temperatures and longer growing seasons occurring in the Alps.

Combined demographic, ecological and genetic tools reveal connectivity within a fragmented butterfly population

Protected species require targeted studies to establish population sizes, their dispersal capacity and the possible genetic bottleneck effect that could impair the future of the remaining populations. In this study, we used the genotyping-by-sequencing technique (SNP: single nucleotide polymorphism) combined with Capture-Mark-Recapture (CMR) method to measure the dispersal ability and subpopulation sizes of the protected butterfly Zerynthia polyxena in 14 sites of NW Italian Alps. The study species form a metapopulation divided into several small subpopulations (ranging from 90 to 859 estimated subpopulation sizes). The species showed low mobility, likely due to habitat fragmentation, with individuals travelling an average of 80 m from their original capture site. SNPs highlighted high observed heterozygosity, low genetic substructuring at short distances, and large genetic differentiation only for individuals found in sites located at 46 km distance, suggesting high gene flow at short distances and limited gene flow between distant populations. Although CMR data did not detect movement beyond 700 m, the genetic results revealed remarkable connectivity among nearby subpopulations. The results indicate that gene flow still exists among the subpopulations despite the fragmented habitat. Considering that the species is locally threatened by habitat loss due to the planning of a European high-speed railway, our data suggest that it is not too late to adopt conservation measures. In conclusion, combining genetic and ecological studies can be utilised to design proper conservation plans for protected and threatened insect metapopulations.

High-resolution temporal variations of nitrate in a high-elevation pond in alpine tundra (NW Italian Alps)

High-resolution temporal measurements in remote, high-elevation surface waters are required to better understand the dynamics of nitrate (NO3−) in response to changes in meteoclimatic conditions. This study reports on the first use of a UV–Vis submersible spectrophotometric probe (UV–Vis probe) to measure the hourly concentration of nitrate nitrogen (NO3−-N) in a pond located at 2722 m a.s.l. in an alpine tundra area (NW Italian Alps), during two snow-free seasons (July–October) in 2014 and 2015. Weekly analyses of NO3−-N and stable isotopes of water (δ18O and δ2H), together with continuous meteorological, water temperature, and turbidity measurements, were performed over the same period. The integration of in-situ UV–Vis spectrophotometric measurements with weekly samples allowed depicting the role of summer precipitation, snow melt, and temperature (air and water) in influencing NO3− dynamics. Short-duration meteorological events (e.g., summer storms and rain-on-snow events) produced rapid variations of in-pond NO3− concentration, i.e., fivefold increase in 18 h, that would not be detectable using the traditional manual collection of discrete samples. The observed seasonal variability of NO3− concentration, negatively correlated with water temperature, highlighted the important role of in-pond biological processes leading to an enhanced N uptake and to the lowest NO3− concentration in the warmer periods. The occurrence of heavy rainfall events critically altered the expected seasonal NO3− trends, increasing the N supply to the pond. The comparison of N dynamics in two years characterised by extremely different meteoclimatic conditions allowed us to obtain insights on the potential effects of climate changes (e.g., high air temperature, heavy rainfalls, and rain-on-snow events) on sensitive aquatic ecosystems as high-elevation ponds.

Tracing fluid infiltration into oceanic crust up to ultra-high-pressure conditions

Fluid–rock interaction within the altered oceanic crust and across the slab–mantle boundary during subduction facilitates element transfer, but the dynamics of fluid transport and fluid–rock exchange during upward fluid migration are still unclear. A study of metamorphic fluid–rock interaction within a section of subducted oceanic crust was carried out on eclogites and metasediments of the ultra-high-pressure Lago di Cignana Unit (NW Italian Alps). The P–T modeling of a quartzschist shows that garnet grew during the prograde and sporadically during the retrograde path and that phengite mainly records the peak to retrograde conditions. Microscale geochemical analysis of garnets has revealed a systematic evolution of oxygen isotopic composition with garnet major element zonation, with extreme within-sample core–rim variations in δ18O between 18 and 4‰ providing evidence for external fluid influx. Garnet in eclogites and calcschists, as well as garnet cores in quartz-rich lithologies, shows normal compositional zoning, as expected for prograde garnet growth, and a relatively constant oxygen isotopic composition. The outer garnet growth zones within a few metasediments show reverse or discontinuous zoning and progressively lower δ18O. Despite major element zoning, the isotopic composition of mica is homogeneous across chemical zoning in one eclogite and one quartzschist, but shows 6‰ variability in another quartzschist. In the underlying Zermatt–Saas serpentinites, antigorite from nine serpentinite samples shows some variation in δ18O, with average δ18O values for individual samples ranging from 1 to 6‰. These results provide evidence for two main stages of external fluid infiltration: (i) fluids from the dehydration of mafic lithologies entered the sequence at peak conditions around 3 GPa, as indicated by the oxygen composition of intermediate zones of mica and garnet, and (ii) low δ18O fluids from serpentinites infiltrated parts of the sedimentary package during exhumation prior to 1.5 GPa, as recorded by the 4‰ garnet outer rims. Samples recording external fluid infiltration are concentrated in the lower part of the sequence, indicating channelized fluid flow, suggesting focused fluid infiltration due to permeability contrasts between metasedimentary and eclogitic lithologies. Channelized fluid flow in the ultra-high-pressure metasediments of Lago di Cignana has not resulted in systematic decarbonation of the metasediments.

Hydrological, thermal and chemical influence of an intact rock glacier discharge on mountain stream water

Rock glaciers are the most prominent permafrost-related mountain landforms. This study investigates the effects of the discharge from an intact rock glacier on the hydrological, thermal and chemical dynamics of a high-elevation stream in the NW Italian Alps. Despite draining only 39 % of the watershed area, the rock glacier sourced a disproportionately large amount of discharge to the stream, with the highest relative contribution to the catchment streamflow occurring in late summer - early autumn (up to 63 %). However, ice melt was estimated to be only a minor component to the discharge of the rock glacier, due to its insulating coarse debris mantle. The sedimentological characteristics and internal hydrological system of the rock glacier played a major role in its capability to store and transmit relevant amounts of groundwater, especially during the baseflow periods. Besides the hydrological influence, the cold and solute-enriched discharge from the rock glacier significantly lowered the stream water temperature (especially during warm atmospheric periods) as well as increased the concentrations of most solutes in the stream. Furthermore, in the two lobes forming the rock glacier, different internal hydrological systems and flowpaths, likely driven by different permafrost and ice content, caused contrasting hydrological and chemical behaviours. Indeed, higher hydrological contributions and significant seasonal trends in solute concentrations were found in the lobe with higher permafrost and ice content. Our results highlight the relevance of rock glaciers as water resources, despite the minor ice melt contribution, also suggesting their potential, increasing hydrological importance in the light of climate warming.

Origin and characteristics of ancient organic matter from a high‐elevation Lateglacial Alpine Nunatak (NW Italy)

AbstractIn high‐mountain areas, Pleistocene glaciations and erosion‐related processes erased most of the pre‐existing landforms and soils. However, on scattered stable surfaces, ancient soils can be locally preserved for long periods, retaining valuable palaeoenvironmental information. Such relict surfaces survived during glaciations either through coverage by non‐erosive, cold‐based, ice or as nunataks. Thus, soils preserved on such surfaces retain an excellent pedo‐signature of different specific past climatic/environmental conditions. In this study, we performed a detailed chemical characterisation of the organic material found in palaeosols, discovered inside periglacial features on a high‐elevation Lateglacial Alpine Nunatak (Stolenberg Plateau), above 3000 m a.s.l. (NW Italian Alps). The soil organic matter (OM) was separated into different pools by means of density fractionation, in order to separate the more fresh/unaltered free and occluded organic material (Light Fraction) from the stable fraction chemically bound to the mineral phase (Mineral Organic Matter—MOM). To better characterise the MOM fraction, this was further subjected to chemical fractionation, in order to separate the alkali‐extractable OM (ext‐MOM) from the fraction intimately bound to minerals. The obtained fractions were then characterised by chemical and 13C nuclear magnetic resonance (NMR), and Fourier Transform Infrared (FT‐IR) spectroscopy. The results indicated that the largest part (>90%) of organic carbon was stored in the stable MOM pool, characterised by a high degree of decomposition and consisting mainly of paraffinic substances, such as lipids and waxes (37–50%), cellulose and hemicellulose (29–37%). The OM likely originated from autochthonous, well‐adapted, ancient alpine vegetation (alpine tundra) that grew on the Plateau during warm climatic phases since the end of the Last Glacial Maximum (LGM). These results further strengthen the palaeoenvironmental reconstruction at the Stolenberg Plateau, which represents a Lateglacial Alpine Nunatak, and has acted as biological refugia (at least) since the end of the LGM.Highlights The origin and composition of ancient organic matter from a high‐elevation Alpine Nunatak were uncovered. More than 90% of organic carbon was stored in the stable mineral organic matter (MOM) pool. Based on NMR and FT‐IR spectra the MOM fraction consisted of paraffinic substances (37–50%), cellulose and hemicellulose (29–37%). The organic matter originated from ancient alpine tundra that developed on the Nunatak since the end of the Last Glacial Maximum.

Snowbed communities and soil C and N dynamics during a four-year investigation in the NW-Italian Alps

ABSTRACT The snowbed habitats represent a relevant component of the alpine tundra biome, developing in areas characterized by a long-lasting snow cover. Such areas are particularly sensitive to climate changes, because small variations in air temperature, rain, and snowfall may considerably affect the pedoclimate and plant phenology, which control the soil C and N cycling. Therefore, it is fundamental to identify the most sensitive abiotic and biotic variables affecting soil nutrient cycling. This work was performed at seven permanent snowbed sites belonging to Salicetum herbaceae vegetation community in the northwestern Italian Alps, at elevations between 2,686 and 2,840 m.a.s.l. During a four-year study, we investigated climate, pedoclimate, floristic composition, phenology, and soil C and N dynamics. We found that lower soil water content and earlier melt-out day decreased soil N-NH4 +, N-NO3 −, dissolved organic carbon (DOC), dissolved organic nitrogen (DON), total dissolved nitrogen (TDN), microbial nitrogen (Nmicr), microbial carbon (Cmicr), and C:Nmicr ratio. The progression of the phenological stages of Salix herbacea reduced soil N-NH4 + and increased DOC. Our results showed that the snow melt-out day, soil temperature, soil water content, and plant phenological stages were the most important factors affecting soil biogeochemical cycles, and they should be taken into account when assessing the effects of climate change in alpine tundra ecosystems, in the framework of long-term ecological research.

Investigation and numerical simulation of debris flow events in Rochefort basin (Aosta Valley—NW Italian Alps) combining detailed geomorphological analyses and modern technologies

This paper presents a multidisciplinary approach using modern technologies for the analysis and modelling of the debris flow that occurred at Torrent Rochefort (Aosta Valley—Italy) September 2015. A detailed on-site geological and geomorphological study was performed to highlight the main characteristics of the basin, useful for validating and calibrating dynamic simulations. The total mobilized volume was estimated by comparing a pre-event DTM and a post-event DTM generated from an unmanned aerial vehicle. A digital terrain model comparative analysis provided a quantitative estimation of erodible depths in different sectors of the Rochefort basin. Numerical modelling of the event was performed using the continuum mechanics-based code RASH3D that enabled a simulation of the dynamic debris motion on complex topography. The results demonstrate the importance of a detailed geomorphological study for the validation and calibration of numerical results. Finally, some considerations were inferred about the magnitude of unstable debris and the possible consequences on local infrastructures.

Physical Modeling of Snow Gliding: A Case Study in the NW Italian Alps

Snow gliding, a slow movement downhill of snow cover, is complex to forecast and model and yet is extremely important, because it drives snowpack dynamics in the pre-avalanching phase. Despite recent interest in this process and the development of some studies therein, this phenomenon is poorly understood and represents a major point of uncertainty for avalanche forecasting. This study presents a data-driven, physically based, time-dependent 1D model, Poli-Glide, able to predict the slow movement of snowpacks along a flow line at the daily scale. The objective of the work was to create a useful snow gliding model, requiring few, relatively easily available input data, by (i) modeling snowpack evolution from measured precipitation and air temperature, (ii) evaluating the rate and extent of movement of the snowpack in the gliding phase, and (iii) assessing fracture (i.e., avalanching) timing. Such a model could be then used to provide hazard assessment in areas subject to gliding, thereby, and subsequent avalanching. To do so, some simplifying assumptions were introduced, namely that (i) negligible traction stress occurs within soil, (ii) water percolation into snow occurs at a fixed rate, and (iii) the micro topography of soil is schematized according to a sinusoidal function in the absence of soil erosion. The proposed model was then applied to the “Torrent des Marais-Mont de La Saxe” site in Aosta Valley, monitored during the winters of 2010 and 2011, featuring different weather conditions. The results showed an acceptable capacity of the model to reproduce snowpack deformation patterns and the final snowpack’s displacement. Correlation analysis based upon observed glide rates further confirmed dependence against the chosen variables, thus witnessing the goodness of the model. The results could be a valuable starting point for future research aimed at including more complex parameterizations of the different processes that affect gliding.

New application of open source data and Rock Engineering System for debris flow susceptibility analysis

This research describes a quantitative, rapid, and low-cost methodology for debris flow susceptibility evaluation at the basin scale using open-access data and geodatabases. The proposed approach can aid decision makers in land management and territorial planning, by first screening for areas with a higher debris flow susceptibility. Five environmental predisposing factors, namely, bedrock lithology, fracture network, quaternary deposits, slope inclination, and hydrographic network, were selected as independent parameters and their mutual interactions were described and quantified using the Rock Engineering System (RES) methodology. For each parameter, specific indexes were proposed, aiming to provide a final synthetic and representative index of debris flow susceptibility at the basin scale. The methodology was tested in four basins located in the Upper Susa Valley (NW Italian Alps) where debris flow events are the predominant natural hazard. The proposed matrix can represent a useful standardized tool, universally applicable, since it is independent of type and characteristic of the basin.

Feasibility and Reliability of the AWIN Welfare Assessment Protocol for Dairy Goats in Semi-extensive Farming Conditions.

The aim of this study was to test the feasibility and reliability of the Animal Welfare Indicators (AWIN) protocol for welfare assessment of dairy goats when applied to semi-extensive farming conditions. We recruited 13 farms located in the NW Italian Alps where three assessors individually and independently applied a modified version of the AWIN welfare assessment protocol for goats integrated with some indicators derived from the AWIN welfare assessment protocol for sheep. The applied protocol consisted of nine individual-level (body condition score, hair coat condition, abscesses, overgrown claws, udder asymmetry, fecal soiling, nasal discharge, ocular discharge, and improper disbudding) and seven group-level (severe lameness, Qualitative Behavior Assessment-QBA, thermal stress, oblivion, Familiar Human Approach Test-FHAT, synchrony at grazing, synchrony at resting) animal-based indicators. On most farms, the level of welfare was good. Many of the considered welfare problems (overgrown claws, fecal soiling, discharges, and thermal stress) were never recorded. However, oblivion, severe lameness, hair coat condition and abscesses were detected on some farms, with percentages ranging from 5 to 35%. The mean percentage of animals with normal body condition was 67.9 ± 5.7. The level of synchronization during resting was on average low (14.3 ± 7.2%). The application of the whole protocol required more than 4 h/farm and 3 min/goat. The inter-observer reliability varied from excellent (udder asymmetry, overgrown claws, discharges, synchrony at resting, use of shelter) to acceptable (abscesses, fecal soiling, and oblivion), but insufficient for hair coat condition, improper disbudding, synchrony at grazing, QBA. Differences in background of the assessors and feasibility constraints (i.e., use of binoculars in unfenced pastures, individual-level assessment conducted during the morning milking in narrow and dark pens, difficulties when using the scan and instantaneous sampling method due to the high number of animals that moved at the same time) can affect the reliability of data collection. Extensive training seems necessary for properly scoring animals when applying the QBA, whereas the FHAT to evaluate the Human-Animal Relationship of goats at pasture seems promising but needs to be validated. Indicators that evaluate the synchrony of activities require to be validated to identify the best moment to perform the observations during the day.

Debris Flow and Rockslide Analysis with Advanced Photogrammetry Techniques Based on High-Resolution RPAS Data. Ponte Formazza Case Study (NW Alps)

The use of a Remotely Piloted Aircraft System (RPAS) for the characterization and monitoring of landslides has been widely improved in the last decade. In particular, the use of this system is particularly effective for the study of areas prone to geohazards. Zones affected by landslides, such as rock slides and debris flows, are often quite critical in terms of accessibility due to unstable blocs that can strongly limit the direct access to the studied area. In this paper, we present the case study of Ponte Formazza in NW Italian Alps. In June 2019, a massive and complex debris flow re-mobilized about 300,000 m3 of a rockslide deposit that occurred in 2009. In this particular environment, we tested traditional, direct and mixed photogrammetric approaches using various configurations of Ground Control Points (GCPs) of the photogrammetric block and by calculating the relative errors. The minimum configuration of GCPs was established to reduce in situ measurements without degrading the accuracy of the cartographic products. The images of three RPAS campaigns (2017, 2018 and 2019), processed with a Structure from Motion (SfM) technique, allowed us to obtain very high-resolution orthophoto and digital surface models (DSMs) before and after the 2019 event. A few GCPs, geolocated with a Global Navigation Satellite System (GNSS), improved the orthophoto and DSM quality (Root Mean Squared Error RMSE 5 cm) even in the areas far from the drone deployment. The availability of high-resolution models has been fundamental for the identification of the volume changes. Furthermore, the 3D view supported and completed the geomorphological mapping of affected areas, particularly in the areas where the field survey is dangerous. The use of ancillary meteorological data and Sentinel-2 satellite images allows for a better definition of the kinematics and the predisposal and triggering factors of the 2019 debris flow.

Hidden soils and their carbon stocks at high-elevation in the European Alps (North-West Italy)

Alpine soils store large quantities of total organic carbon (TOC). Given their high sensitivity to climate change, they may release large amounts of CO2 in a warming climate scenario. Thus, it is important to know their C stocks in order to estimate its possible release. While C stocks of forest, dwarf shrub and alpine grassland soils are well documented, little is known about soils and C stocks in high-elevated periglacial environments dominated by frost-driven processes. The object of this study is the periglacial environment of the Stolenberg Plateau (LTER site Istituto Mosso, 3030 m a.s.l.), at the foot of the Monte Rosa Massif (NW Italian Alps). The plateau is mostly covered by a thick stony layer, organized in periglacial blockfields and blockstreams. The plant cover reaches only 3–5%. During the construction of a chair lift, open trenches revealed, unexpectedly, well-developed soils under the active periglacial stone cover. In particular, thick (30–65 cm) and dark TOC-rich A horizons were observed. Below these Umbric horizons, Cambic Bw ones were developed but discontinuous. Despite the lack of vegetation, C stocks were remarkably high (up to ~ 5 kg m−2), comparable to vegetated soils at lower elevation. Non-invasive geophysical methods revealed that these hidden soils were widespread on the plateau under the stony cover, with a mean thickness of around 50 cm. These TOC-rich soils, without vegetation and covered by periglacial landforms, represent a unique pedoenvironment suggesting new perspectives on the actual C-stocks at high-elevation sites, which are probably underestimated.

A rock-glacier – pond system (NW Italian Alps): Soil and sediment properties, geochemistry, and trace-metal bioavailability

Rock-glacier sediment transfer and ice melting can impact surface waters located downstream. However, there is a lack of knowledge on the influence of rock-glacier dynamics on the geochemical, hydrochemical, and ecological characteristics of adjacent impounded surface waters. In the Col d'Olen area (Long-Term Ecological Research site, NW Italian Alps), an intact rock glacier terminates into a pond and solute-enriched waters originating from the rock glacier flow into the pond through a subsurface hydrological window. In this study, we performed geophysical and ground surface temperature measurements. Moreover, we sampled soils and sediments in different compartments of the investigated rock-glacier - pond system and we further sampled benthic invertebrates in the pond. Cold ground thermal regime, ground-ice presence, and coarse debris cover on the rock glacier together with its lithology (serpentinites) influence the rock-glacier geochemistry and ecology with respect to surrounding areas. Pond geochemistry is affected by transfer of trace-metal-enriched fine-grained debris and meltwaters from the rock glacier. Enhanced bioavailability of serpentinite-associated trace metals was proved, with concentrations of Ni and Cr in benthic invertebrates up to 384 and 110 mg kg−1 d.w., respectively, potentially exerting toxic effects on pond biota. The advancing movement of the rock glacier not only has delivered sediments to the pond, but it has progressively filled the valley depression where the pond is located, creating a dam that could have modified the level of impounded water. This process likely constituted a sediment trap in which serpentinitic rock-glacier sediments could be deposited at the pond bottom, with related geochemical and ecological implications. This study illustrates the importance of rock glaciers in influencing the characteristics of downstream freshwater bodies and highlights the need to improve our knowledge about climate-change-related impacts of rock-glacier dynamics on alpine headwaters.

Snow Avalanche Impact Measurements at the Seehore Test Site in Aosta Valley (NW Italian Alps)

In full-scale snow avalanche test sites, structures such as pylons, plates, or dams have been used to measure impact forces and pressures from avalanches. Impact pressures are of extreme importance when dealing with issues such as hazard mapping and the design of buildings exposed to avalanches. In this paper, we present the force measurements recorded for five selected avalanches that occurred at the Seehore test site in Aosta Valley (NW Italian Alps). The five avalanches were small to medium-sized and cover a wide range in terms of snow characteristics and flow dynamics. Our aim was to analyze the force and pressure measurements with respect to the avalanche characteristics. We measured pressures in the range of 2 to 30 kPa. Though without exhaustive measurements of the avalanche flows, we found indications of different flow regimes. For example, we could appreciate some differences in the vertical profile of the pressures recorded for wet dense avalanches and powder ones. Being aware of the fact that more complete measurements are necessary to fully describe the avalanche flows, we think that the data of the five avalanches triggered at the Seehore test site might add some useful information to the ongoing scientific discussion on avalanche flow regimes and impact pressure.

High export of nitrogen and dissolved organic carbon from an Alpine glacier (Indren Glacier, NW Italian Alps)

Mountain glaciers can export large amounts of nitrogen (N) and carbon (C) to downstream aquatic ecosystems. To date, however, the number of studies that analysed concentrations and fluxes of N forms and dissolved organic carbon (DOC) from glaciers in the European Alps and worldwide is limited, given the high complexity of data gathering in harsh high-elevation environments. In this work, we rely upon new, unexploited data from field campaigns pursued during 2012–2015 at high elevations (> 3000 m a.s.l.) of the Indren Glacier (NW Italian Alps) to (1) develop glacio-hydrological modelling and stream flow estimates within a heavily glacier-fed catchment, (2) provide N forms and DOC concentrations and estimated fluxes in meltwater, and (3) provide possible explanations of cryospheric control upon water chemistry. Water and soil samples were also collected at two lower-elevation sites along the glacial stream to investigate the downstream variability of N forms and DOC. Nitrate-N, dissolved organic nitrogen, and DOC concentrations (0.21 ± 0.12, 0.19 ± 0.14, 1.16 ± 0.63 mg L−1, respectively) and yields (220, 210, 1279 kg km−2 year−1, respectively) were among the highest considering other glaciated areas of the globe, probably due to high atmospheric N and C depositions. Limited effect of soil on water characteristics was found and attributed to the reduced soil development in recently deglaciated areas (after the Little Ice Age), thus underlining the role of glacier melting in determining N and C dynamics in high-elevation, Alpine surface waters.

Influence of permafrost, rock and ice glaciers on chemistry of high-elevation ponds (NW Italian Alps)

Permafrost degradation, rock-glacier thawing, and glacier retreat are influencing surface water quality at high elevations. However, there is a lack of knowledge on the dominant geochemical reactions occurring in different cryospheric conditions and how these reactions change during the ice-free season. In the Col d'Olen area (LTER site, NW Italian Alps), four ponds with similar sizes, located in basins with different cryospheric features (glacier, permafrost, rock glacier, none of these), are present in a geographically limited area. All ponds were sampled weekly in 2015 and partially in 2014. Major ions, selected trace elements, and biotic parameters (dissolved organic carbon-DOC, fluorescence index-FI, and nitrate) are examined to evidence the effect of different cryospheric features on water characteristics. Where cryospheric conditions occur chemical weathering is more intensive, with strong seasonal increase of major ions. Sulphide oxidation dominates in glacier and permafrost lying on acid rocks, probably driven by enhanced weathering of freshly exposed rocks in subglacial environment and recently deglaciated areas, and active layer thickness increase. Differently, carbonation dominates for the rock glacier lying on ultramafic rocks. There, high Ni concentrations originate from dissolution of Mg-bearing rocks in the landform. In all settings, pH neutralisation occurs because of the presence of secondary carbonate lithology and ultramafic rocks. Nitrate highest concentrations and changes occur in cryospheric settings while DOC and FI do not show strong differences and seasonal variations. The establishment of more frequent monitoring for water quality in high-elevated surface waters is necessary to provide greater statistical power to detect changes on longer time scales.

Butterfly distribution along altitudinal gradients: temporal changes over a short time period

Mountain ecosystems are particularly sensitive to changes in climate and land cover, but at the same time, they can offer important refuges for species on the opposite of the more altered lowlands. To explore the potential role of mountain ecosystems in butterfly conservation and to assess the vulnerability of the alpine species, we analyzed the short-term changes (2006–2008 vs. 2012–2013) of butterflies’ distribution along altitudinal gradients in the NW Italian Alps. We sampled butterfly communities once a month (62 sampling stations, 3 seasonal replicates per year, from June to August) by semi-quantitative sampling techniques. The monitored gradient ranges from the montane to the alpine belt (600–2700 m a.s.l.) within three protected areas: Gran Paradiso National Park (LTER, Sitecode: LTER_EU_IT_109), Orsiera Rocciavrè Natural Park and Veglia Devero Natural Park. We investigated butterflies’ temporal changes in accordance with a hierarchical approach to assess potential relationships between species and community level. As a first step, we characterized each species in terms of habitat requirements, elevational range and temperature preferences and we compared plot occupancy and altitudinal range changes between time periods (2006–2008 vs. 2012–2013). Secondly, we focused on community level, analyzing species richness and community composition temporal changes. The species level analysis highlighted a general increase in mean occupancy level and significant changes at both altitudinal boundaries. Looking at the ecological groups, we observed an increase of generalist and highly mobile species at the expense of the specialist and less mobile ones. For the community level, we noticed a significant increase in species richness, in the community temperature index and a tendency towards homogenization within communities. Besides the short time period considered, butterflies species distribution and communities changed considerably. In light of these results, it is fundamental to continue monitoring activities to understand if we are facing transient changes or first signals of an imminent trend.

Climatic and pedoclimatic factors driving C and N dynamics in soil and surface water in the alpine tundra (NW-Italian Alps)

In alpine tundra the interannual and seasonal variability of C and N forms in soil and lake water during the short snow-free season could be significant and related to climatic and pedoclimatic variables. The hypothesis that not only the climatic and pedoclimatic parameters recorded during the summer season but also the ones measured during the previous snow-covered season could contribute to explaining the C and N dynamics in soil and surface water was tested along 10 snow-free seasons in 3 sites in the alpine tundra in the north-western Italian Alps (LTER site Istituto Mosso). Among the considered parameters, the snow cover duration (SCD) exerted a primary control on soil N-NH4+, DOC, Cmicr, Nmicr and DOC:DON ratio, with an inverse relationship. A long SCD might cause the consumption of all the subnival substrata by the soil microorganisms, determining a C starvation during the subsequent snow-free season. An opposite trend was observed for the lake water, where a longer SCD corresponded to a higher content of inorganic N forms. Among the pedoclimatic indices, the number of soil freeze/thaw cycles (FTC) recorded during the snow-covered season had a positive relation with most of soil C and N forms and N-NO3− in lake water. Only the soil DON showed an inverse pattern, and this result is consistent with the hypothesis that FTC released soil DON, subsequently decomposed and mineralized. Only N-NO3− had a significant intraseasonal variability, reaching the highest values in September both in soil and water, revealing a significant slowdown of the contribution of soil N immobilization processes.

Ice Thickness Estimation from Geophysical Investigations on the Terminal Lobes of Belvedere Glacier (NW Italian Alps)

: Alpine glaciers are key components of local and regional hydrogeological cycles and real-time indicators of climate change. Volume variations are primary targets of investigation for the understanding of ongoing modifications and the forecast of possible future scenarios. These fluctuations can be traced from time-lapse monitoring of the glacier topography. A detailed reconstruction of the ice bottom morphology is however needed to provide total volume and reliable mass balance estimations. Non-destructive geophysical techniques can support these investigations. With the aim of characterizing ice bottom depth, ground-penetrating radar (GPR) profiles and single-station passive seismic measurements were acquired on the terminal lobes of Belvedere Glacier (NW Italian Alps). The glacier is covered by blocks and debris and its rough topography is rapidly evolving in last years, with opening and relocation of crevasses and diffuse instabilities in the frontal sectors. Despite the challenging working environment, ground-based GPR surveys were performed in the period 2016–2018, using 70-MHz and 40-MHz antennas. The 3D ice bottom morphology was reconstructed for both frontal lobes and a detailed ice thickness map was obtained. GPR results also suggested some information on ice bottom properties. The glacier was found to probably lay on a thick sequence (more than 40 m) of subglacial deposits, rather than on stiff bedrock. Week deeper reflectors were identified only in the frontal portion of the northern lobe. These interfaces may indicate the bedrock presence at a depth of around 80 m from the topographic surface, rapidly deepening upstream. Single-station passive seismic measurements, processed with the horizontal-to-vertical spectral ratio (HVSR) method, pointed out the absence of sharp vertical contrast in acoustic impedance between ice and bottom materials, globally confirming the hypotheses made on GPR results. The obtained results have been compared with previous independent geophysical investigations, performed in 1961 and 1985, with the same aim of ice thickness estimation. The comparison allowed us to validate the results obtained in the different surveys, supply a reference base map for the glacier bottom morphology and potentially study ice thickness variations over time.