Papers by Michele Freppaz
Sustainability, 2021
We studied the effects of three soil management approaches (permanent grassing, chemical weeding,... more We studied the effects of three soil management approaches (permanent grassing, chemical weeding, and buffer strips), and the additional impact of tractor passage on soil erosion in a sloping vineyard located in the inner part of Aosta Valley (N-W Italian Alps). The vineyard rows were equipped with a sediment collection system with channels and barrel tanks. A total of 12 events with sediment production were observed across 6 years, and the collected sediments were weighted and analyzed. Average erosion rates ranged from negligible (mainly in grassed rows) to 1.1 t ha−1 per event (after weeding). The most erosive event occurred in July 2015, with a total rainfall of 32.2 mm, of which 20.1 were recorded in 1 h. Despite the limited number of erosive events observed, and the low measured erosion rates, permanent grassing reduced soil erosion considerably with respect to weeding; buffering had a comparable effect to grassing. The tractor passage, independent of the soil management appro...
Science of The Total Environment, 2018
Mountain ecosystems are sensitive and reliable indicators of climate change. Long-term studies ma... more Mountain ecosystems are sensitive and reliable indicators of climate change. Long-term studies may be extremely useful in assessing the responses of high-elevation ecosystems to climate change and other anthropogenic drivers from a broad ecological perspective. Mountain research sites within the LTER (Long-Term Ecosystem Research) network are representative of various types of ecosystems and span a wide bioclimatic and elevational range. Here, we present a synthesis and a review of the main results from long-term ecological studies in mountain ecosystems at 20 LTER sites in Italy, Switzerland and Austria covering in most cases more than two decades of observations. We analyzed a set of key climate parameters, such as temperature and snow cover duration, in relation to vascular species composition, plant traits, abundance patterns, pedoclimate, nutrient dynamics in soils and water, phenology and composition of freshwater biota. The overall results highlight the rapid response of mountain ecosystems to climate change, with site-specific characteristics and rates. As temperatures increased, vegetation cover in alpine and subalpine summits increased as well. Years with limited snow cover duration caused an increase in soil temperature and microbial biomass during the growing season. Effects on freshwater ecosystems were also observed, in terms of increases in solutes, decreases in nitrates and changes in plankton phenology and benthos communities. This work highlights the importance of comparing and integrating long-term ecological data collected in different ecosystems, both terrestrial and freshwater, for a more comprehensive overview of the ecological effects of climate change. Nevertheless, there is a need for (i) adopting co-located monitoring site networks to improve our ability to obtain sound results from cross-site analysis, (ii) carrying out further studies, in particular short-term analyses with fine spatial and temporal resolutions to improve our understanding of responses to extreme events, and (ii) increasing comparability and standardizing protocols across networks to clarify local patterns from global patterns.
Mountain ecosystems are highly vulnerable to flash flood phenomena, which can result in sudden so... more Mountain ecosystems are highly vulnerable to flash flood phenomena, which can result in sudden soil water saturation and surface erosion. Saturated soils are vulnerable to solifluction and liquefaction, depending on soil plastic properties. Surface erosion and mass movements create serious hazards for the population and the infrastructures: the recognition and mapping of areas characterized by different vulnerability to erosion processes are of primary importance in order to properly manage the land use and the hydro-geological hazards. The study area is the whole Val d’Aosta region, characterized by a wide range of geological substrates, vegetation types, altitude variations and pedoclimates (from perudic in south-east and at high altitude to xeric-ustic in the intra-alpine central valley). All genetic horizons from 150 soil profiles have been described and analyzed (standard chemical analysis and Atterberg limits), in order to understand how pedogenic processes influence soil plas...
CATENA, 2015
Soil degradation by processes such as soil erosion, shallow landslides, debris-flows etc. is a si... more Soil degradation by processes such as soil erosion, shallow landslides, debris-flows etc. is a significant problem in mountain areas, and is a crucial issue for natural hazard assessment in mountain areas. Several soil properties, among which are the liquid and plastic limits, i.e. moisture contents for which a soil passes from the plastic to liquid state (liquid limit, LL) and from the semisolid to plastic state (PL, plastic limit), have been proposed as indicators for soil vulnerability to degradation processes, both of natural and anthropogenic origin. In this research we investigated the liquid and plastic limits of the main soil groups of World Reference Base for Soil Resources (WRB) classification present in Aosta Valley (N-W Italian Alps) from a pedogenic perspective. In particular, we compared 1) soils at different stages of development; 2) different genetic horizons. Our main aim was to provide and interpret data on soils' consistency and mechanical behavior that may be used as indexes for the assessment of soil vulnerability. Despite its relatively small area, the Aosta Valley is characterized by a wide range of soil types. Sixty-two soils with different profile evolution stages, representative of 7 WRB soil groups, were investigated and LL and PL in genetic horizons were studied at the soil type and genetic horizons level. In general, soil consistency was largely determined by the organic matter content (both in topsoils and organic matter-enriched subsurface horizons), but in spodic horizons and some C horizons a role of poorly crystalline and pedogenic iron oxides was observed too. Considering the vulnerability to consistency loss, that can result in erosion processes and overall soil degradation, surface horizons were generally less vulnerable, as could be expected on the basis of previous research, i.e. showed higher LL and PL values, than the deeper ones, generally characterized by a reduction of soil consistency. Therefore, topsoil could receive higher water inputs while still preserving their consistency and strength. This was not confirmed in Podzols, where the organic matter enrichment of spodic horizons determined a discontinuity in physical properties between the E horizons (more vulnerable) and the underlying, spodic ones. The same trend was observed for Calcisols with a deep cemented Bkm horizon. The research provided a novel overview on LL and PL in the common soil types present in the Alpine region, integrating the already existing research on topsoil vulnerability to degradation processes (erosion, consistency losses, losses of strength), and the regional soils database. The use of LL and PL as indicators of soil physical quality was approached with a pedogenic perspective, which might be helpful for a better definition of hazard assessment at the regional scale.
In agreement with the idea of the ISSW "a merging of theory and practice", we describe ... more In agreement with the idea of the ISSW "a merging of theory and practice", we describe the activities carried out in Aosta Valley (NW Italy) for the formation of avalanche experts. In particular, within the Operational programme 'Italy -France (Alps -ALCOTRA)' Projects "DynAval -Dynamique des avalanches: départ et interactions ecoulement/obstacles" and "RiskNat", we organized three courses focused on the following topics : 1) artificial avalanche release, 2) snowpack slow movements and load on defense structures, 3) interaction avalanche flow / obstacles. The courses were directed mainly to avalanche experts in order, on one hand, to show them the most recent scientific findings by researchers, and, on the other hand, to give them practical information ready to be used in their expertise. On this line, we also published guide lines concerning: 1) avalanche release zone, 2) interaction avalanche flow/obstacles, 3) snowpack stability, 4) artificia...
Italian Journal of Agronomy, 2011
Negli ambienti agro-forestali alpini la neve permane al suolo dai sei agli otto mesi all'anno in ... more Negli ambienti agro-forestali alpini la neve permane al suolo dai sei agli otto mesi all'anno in relazione alla quota ed alla esposizione. L'acqua è quindi immobilizzata allo stato solido per la maggior parte del periodo invernale e rilasciata al suolo in un breve periodo di tempo nel corso del disgelo primaverile. In questi ambienti il regime delle precipitazioni nevose esercita un ruolo fondamentale nel condizionare la temperatura e la dinamica degli elementi nutritivi del suolo, ed in particolare dell'azoto, con significative conseguenze sulla nutrizione vegetale. Il riposo vegetativo, le basse temperature e la diffusa copertura nevosa suggeriscono infatti che l'attività biologica del suolo sia concentrata soltanto durante la stagione estiva. In realtà i suoli ricoperti da un consistente manto nevoso sono isolati dalla temperatura dell'aria e possono non gelare nel corso dell'inverno. Un manto nevoso di sufficiente spessore, infatti, accumulatosi presto nella stagione invernale, è in grado di isolare il suolo dall'ambiente circostante mantenendo la temperatura prossima agli 0 °C nel corso della stagione invernale. L'innalzamento del limite delle nevicate e la riduzione della permanenza della neve al suolo in seguito al riscaldamento globale (IPCC, 1996, 2001) può però determinare una riduzione dell'effetto isolante del manto nevoso, esponendo i suoli del piano montano superiore a temperature più basse e ad una maggiore frequenza di cicli gelo/disgelo che possono alterare la dinamica della sostanza organica e la disponibilità di nutrienti nel suolo. Tali stress termici possono determinare la lisi delle cellule microbiche ed il conseguente incremento della mineralizzazione dell'azoto e del carbonio ad opera dei microrganismi sopravvissuti. È inoltre emerso come l'azione dei cicli gelo/disgelo possa determinare l'esposizione di superfici di scambio prima non disponibili, con il rilascio ad esempio di forme di azoto organico di origine non microbica, successivamente mineralizzate. La ridotta o assente attività di immobilizzazione microbica può concorrere a determinare l'accumulo di notevoli quantità di azoto inorganico nel suolo, potenzialmente lisciviabile nel corso del disgelo primaverile, quando le piante non hanno ancora ripreso l'attività vegetativa. La riduzione delle precipitazioni nevose negli ambienti agro-forestali alpini può quindi avere un significativo effetto sul regime termico dei suoli e conseguentemente sul ciclo degli elementi nutritivi. Le ricadute ambientali non possono che essere valutate nel tempo, attraverso studi mirati, in grado di evidenziare gli effetti indiretti del cambiamento climatico in atto sulle caratteristiche dei pedoambienti alpini.
The presence of a thick snowpack could interfere on forest stability especially on steep slopes: ... more The presence of a thick snowpack could interfere on forest stability especially on steep slopes: potential consequences include superficial soil erosion and damage of young and old stands, due to snow pressure and movements. The aim of this work is to determine the pressure of the snowpack on stems in forest with different tree composition. The study site is located
Among the potential effects of climate change in the Alpine environment during the winter, of par... more Among the potential effects of climate change in the Alpine environment during the winter, of particular interest are the shift of the snowline toward higher altitude and the increase in frequency of rain events on the snowpack. Here, we present the implementation of a new, mid-to-long term study site to simulate these changes in precipitation regimes and determine their influences on soil carbon and nutrient cycles in forest environment. The study site is located in a forest (Larch stand), at 2020 m a.s.l., in Piedmont (NW-Italy) and includes tree plots equipped with soil moisture and temperature sensors: in the first plot the snow is removed, during December and January, to simulate a winter with late snowfall; in the second plot the snow is drizzle, in January, with liquid water chemically comparable to rain; in the control plot, the snowpack is left undisturbed. Tree repetitions for each treatment are equipped, at 30 cm of depth, with two suction lysimeters in order to weekly sample the soil solution where dissolved organic matter, inorganic N, microbial biomass C and N will be determined. Additionally, tree repetitions for each snow treatment are used as snow fields, for snow chemical analyses, to quantify ionic input to the soil, and physical characterization, in order to evaluate the influence of treatmentinduced changes in snow density and grain composition on soil temperature and moisture regimes. Data will be collected during the ongoing winter (2009-2010), but we also attempt to get a mid-term effect by repeating the experiments during next winter seasons.
You may download, copy and otherwise use the AAM for non-commercial purposes provided that your l... more You may download, copy and otherwise use the AAM for non-commercial purposes provided that your license is limited by the following restrictions: (1) You may use this AAM for non-commercial purposes only under the terms of the CC-BY-NC-ND license.
Natural Hazards and Earth System Sciences, 2014
Soil erosion in Alpine areas is mainly related to extreme topographic and weather conditions. Alt... more Soil erosion in Alpine areas is mainly related to extreme topographic and weather conditions. Although different methods of assessing soil erosion exist, the knowledge of erosive forces of the snow cover needs more investigation in order to allow soil erosion modeling in areas where the snow lays on the ground for several months. This study aims to assess whether the RUSLE (Revised Universal Soil Loss Equation) empirical prediction model, which gives an estimation of water erosion in t ha yr −1 obtained from a combination of five factors (rainfall erosivity, soil erodibility, topography, soil cover, protection practices) can be applied to mountain areas by introducing a winter factor (W), which should account for the soil erosion occurring in winter time by the snow cover. The W factor is calculated from the ratio of Ceasium-137 (137 Cs) to RUSLE erosion rates. Ceasium-137 is another possible way of assessing soil erosion rates in the field. In contrast to RUSLE, it not only provides waterinduced erosion but integrates all erosion agents involved. Thus, we hypothesize that in mountain areas the difference between the two approaches is related to the soil erosion by snow. In this study we compared 137 Cs-based measurement of soil redistribution and soil loss estimated with RUSLE in a mountain slope affected by avalanches, in order to assess the relative importance of winter erosion processes such as snow gliding and full-depth avalanches. Three subareas were considered: DS, avalanche defense structures, RA, release area, and TA, track area, characterized by different prevalent winter processes. The RUSLE estimates and the 137 Cs redistribution gave significantly different results. The resulting ranges of W evidenced relevant differences in the role of winter erosion in the considered subareas, and the application of an avalanche simulation model corroborated these findings. Thus, the higher rates obtained with the 137 Cs method confirmed the relevant role of winter soil erosion. Despite the limited sample size (11 points), the inclusion of a W factor in RUSLE seems promising for the improvement of soil erosion estimates in Alpine environments affected by snow movements.
Agriculture, Ecosystems & Environment, 2015
Mountain agriculture needs to face several limitations related to climate and topography. Land le... more Mountain agriculture needs to face several limitations related to climate and topography. Land levelling, reshaping, and terracing are widely adopted in Europe, in order to ease mechanization and make agriculture more rentable. However, while the economic and productive benefits of these operations are well known, the effects on soil chemical and physical properties are not always assessed, and need constant monitoring over time. Intense soil rebuilding has been carried out in Aosta Valley (NW Italian Alps) to improve the accessibility and mechanization, including irrigation, of mountain grasslands. In this research we present studied on 3 soil chronosequences established in grasslands subject to soil rebuilding practices. The aim was to investigate the effects of land-reshaping operations on soil chemical and physical properties over time, by comparing changes in some selected soil properties such as organic C and soil laboratory indexes for quantifying soil structural resistance. The soil profiles generally showed a simpler morphology after rebuilding. Soil structure and consistency, that are recognized as soil physical quality indicators, after a sharp negative effect of the disturbance (i.e. decrease in Liquid limit, increased soil aggregates loss) generally showed a trend towards the restoration of the characteristics of the original soils in the medium or long-term time span. Despite the limited sample size, the results represent a first attempt to assess the effects of a technique which is being more and more applied in a mountain region, such as the Aosta Valley Region, where manufactured soils are a significant part of agricultural land. The main findings of our research indicated that: 1) structure and consistency of soils (i.e. aggregate loss, LL, PL) can be used as indicators of soil quality in response of anthropogenic soil disturbance due to land-reshaping operations, as they reflect the evolution of soil properties after intense disturbance; 2) after disturbance, soil recovery was relatively quick, despite the strong deterioration of the physical quality in the immediate (~6-12 months) aftermath of the operations.
After the maximum expansion phase of the Little Ice Age, soils located in proglacial areas in the... more After the maximum expansion phase of the Little Ice Age, soils located in proglacial areas in the Italian Alps evolved over a time span of about 190 years. In the future, as a consequence of climate change, additional areas will become ice-free and therefore subject to pedogenesis. In such conditions, ice retreat time and topography are expected to play a major role among soil formation factors. Due to extreme environmental characteristics, soil evolution will be rather slow, and heavily influenced by severe soil loss phenomena (e.g. water erosion due to extreme rainfall event and snowmelt, avalanche erosion). We investigated the soil formation along a glacial chronosequence of an Alpine glacier foreland. The Pré de Bar glacier is located in North West Italy (Aosta Valley Region), in the Mont Blanc massif, between 3750 and 2150 m a.s.l. and it covers an area of 340 ha. The glacier was chosen because of the availability of old photographs documenting the glacier retreat phases starti...
… 2010, held 2-7 May …, 2010
The development of winter sports determines an increasing impact on the high altitude ecosystems,... more The development of winter sports determines an increasing impact on the high altitude ecosystems, as a consequence of increased participation and an increasing demand of high quality standards for skiable areas. The construction of a ski slope is ...
Journal of Soils and Sediments, 2014
Purpose: Climate change is driving strong variations in mountain habitats, such as glacier retrea... more Purpose: Climate change is driving strong variations in mountain habitats, such as glacier retreat, which is releasing large surfaces soon colonized by vegetation and attacked by weathering and pedogenesis. Many proglacial soil chronosequences have been studied in different parts of the world, but no study is available on early soil development and pedogenesis on serpentinite. Materials and methods: We analyzed the development of the main chemical (pH, organic matter, nutrients and exchangeable cations) and morphological properties in three soil chronosequences in the Verra Grande Glacier forefield (Italian side of the Monte Rosa Group, Western Alps), characterized by slightly different parent materials (pure serpentinite or serpentinite with small gneiss inclusions) and topography (steep lateral moraines or flat basal till). Results and discussion: Organic matter accumulation, acidification and base and metal leaching are the most important pedogenetic processes active during early stages of soil formation on serpentinite in the upper subalpine altitudinal belt. These processes are associated with minor changes in color and structure showing weak mineral weathering. Biocycling of nutrients is limited on pure serpentinite because of weak primary productivity of the plant community. Pedogenesis is quite slow throughout the forefield, and it is slowest on pure serpentinite. On flat surfaces, where slow erosion permits a fast colonization by Ericaceae, the podzolization process begins after few centuries since moraine deposition, while on steep slopes more time is required. Conclusions: Pedogenesis on serpentinite is extremely slow. The fast colonization by grassland species increases the speed of pedogenetic trends where serpentinitic till is enriched by small quantities of P-rich gneiss. The encroachment of forest-shrub species increases the speed of pedogenetic trends thanks to a strong nutrient biocycling.
Journal of Maps, 2013
Mountain vineyards are a valuable resource for high quality wine production and landscape conserv... more Mountain vineyards are a valuable resource for high quality wine production and landscape conservation. A suitability map (1: 50.000) for mountain vineyard cultivation was created in GIS environment for a study area located in Aosta Valley (NW Italy). We considered the following environmental variables that are known to influence wine production: slope, aspect, altitude, soil, obtaining a suitability map that allowed to identify the areas that can be considered to carry out a sustainable mountain viticulture.
Hydrological Processes, 2013
Among the potential effects of climate change on subalpine forest ecosystems during the winter se... more Among the potential effects of climate change on subalpine forest ecosystems during the winter season, the shift of the snowline toward higher altitude and the increase in frequency of rain events on the snowpack are of particular interest. Here we present the results of a 2 year field experiment conducted in a forest stand (Larix decidua) in NW Italy at 2020 m a.s.l. From 2009 to 2011 we monitored soil physical characteristics (temperature and moisture), and soil and soil solution chemistry (C and N forms and their changes in time) as affected by late snowpack accumulation and rain on snow events. Late snowpack accumulation determined a stronger effect on soil thermal and moisture regimes than rain on snow events. Also soil chemistry was significantly affected by late snowfall simulation. Although microbial carbon and nitrogen were not influenced by soil freezing, the soil contents of more labile soil carbon and nitrogen forms (DOC and DON) and inorganic nitrogen increased when the soil froze. Variations in the soil solution were shifted with respect to those observed in soil, with an increase in DON and N-NO 3 concentrations occurring during spring and summer. This study highlights the potential N loss in subalpine soils under changing environmental conditions driven by a changing climate.
Environmental Science & Technology, 2008
Cold Regions Science and Technology, 2010
Major element chemistry of the snow cover was investigated at 15 sampling sites at about 2000 m a... more Major element chemistry of the snow cover was investigated at 15 sampling sites at about 2000 m a.s.l. in the Aosta Valley Region (North Western Italy), an inner alpine region characterized by a continental climate, during late winter 2005-2006. Snowfall in winter 2005-2006 was primarily due to westerly, Atlantic air flows, while southerly flows were not a significant source of precipitation. These two factors (i.e. the inner alpine topography and the peculiar air flow patterns) determined a unique ion distribution compared to rest of the Alps. Calcium and magnesium concentrations in snowpacks were low, consistent with the absence of Saharan dust events and local geological sources. Sodium and chloride concentrations were higher than the average for the Alps, supporting the influence of the Atlantic air masses on the ionic composition of snowfall. Sulfate concentrations were in the range of background concentrations reported for high altitude and latitude sites, indicating that industrial emissions were not a main source of chemicals in Aosta Valley snowpacks for winter 2005-2006. Ammonium and nitrate values were comparable to concentrations found in other sites of the Alps for low-emission winters. We estimated dissolved inorganic nitrogen stored in snow to range between 0.25 and 0.75 kg N ha − 1 , corresponding to about 2-6% of the over-winter-N mineralization in Alpine soils in the Western Alps. In the Aosta Valley, local biogenic pollution rather than long-range transport may contribute substantially to the ionic load in the snowpack when westerly air masses are the main source of precipitation. Although conducted over only one winter season, this study suggests a peculiar and previously unreported pattern of snowpack chemistry, that may be representative of the inner alpine, continental valleys in the absence of strong anthropogenic pollution or dust deposition. Due to the fact that inner alpine valleys cover a non-negligible surface of the Alps, we suggest these patterns to be taken into account while modeling ion depositions at a global scale.
CATENA, 2014
Climate change has huge impacts on alpine ecosystems. One of the most visible effects in the Alps... more Climate change has huge impacts on alpine ecosystems. One of the most visible effects in the Alps is glacier retreat since the end of the Little Ice Age (LIA), which caused the exposure of previously glaciated surfaces. These surfaces are open-air laboratories, verifying theories regarding ecosystem and soil development. In order to increase our knowledge on the effects of time and vegetation primary succession on soil development in proglacial areas, we sampled soils and surveyed plant communities on stable points in the proglacial area of the Lys glacier, in the Italian northwestern Alps (Valle d'Aosta Region). The sampling points were located on dated sites (based on literature and/or historical photographs). Glacial till is attacked by weathering processes immediately after deposition and stabilization, with a consequent loss of soluble compounds, decrease of pH and primary mineral weathering. The speed of these processes was largely increased after the establishment of a continuous vegetation cover, thanks to the organic matter accumulation caused by litter input and root decomposition below the soil surface. On sialic glacial tills, below timberline and under a quasi-climax larch-Rhododendron forest, fast and steady decrease in pH values, increase in organic matter content and horizon differentiation were observed. In particular, genetic eluvial horizons formed in approximately 60 years, while diagnostic albic horizons were developed after ca. 90 years, pointing to an early start of the podzolization processes. Cheluviations of Fe and, secondarily, Al were analytically verified. However, illuviations of Fe, Al and organic matter in incipient B horizons were not sufficient to obtain diagnostic spodic horizons on LIA materials. Under grazed grassland below timberline and alpine prairie above timberline, acidification and weathering were slightly slower, and no redistribution with the depths of Fe and Al oxi-hydroxides was observed. A cambic Bw horizon developed on the oldest LIA moraines. Therefore it seemed that this fast onset of the podzolization process in comparison to other proglacial chronosequences in the Alps was mainly driven by vegetation properties rather than by specific climatic conditions.
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Papers by Michele Freppaz