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Purpose: Global warming is expected to change the thermal and hydrological soil regime in permafrost ecosystems which might impact soil erosion processes. Erosion assessment using radionuclides can provide information on past and ongoing, i.e. time-split, processes. The focus of this work was to find out if permafrost soils in the Swiss Alps differ in their medium- and long-term erosion rates from non-permafrost soils and if rates have accelerated during the last few decades. Materials and methods: Using cosmogenic (meteoric Be) and anthropogenic radionuclides (Cs, Pu), a time-split approach was achieved by determining erosion activities on the long (millennia; Be) and medium term (decades; Cs, Pu). Additionally, the stable isotope δC signature in soil organic matter was used as a qualitative indicator for soil disturbance patterns. We compared soil erosion processes in permafrost soils and nearby unfrozen soils in the alpine (sites at 2,700 m asl, alpine tundra) and the subalpine (sites 1,800 m asl, natural forest) range of the Swiss Alps (Upper Engadine). Cs, Pu and δC measurements were performed at the alpine sites only. Results and discussion: Depending on the calculation procedure (profile distribution model or inventory method), the Cs measurements revealed soil accumulation rates of 1-3 t/km/year in permafrost soils and 34-52 t/km/year in non-permafrost soils. However, due to snow cover and subsequent melt-water runoff during Cs deposition after the Chernobyl accident, caesium does not seem to be an appropriate soil erosion tracer on the investigated alpine sites. With Pu, more reliable results were achieved. Pu measurements provided erosion rates of 31-186 t/km/year in permafrost soils and accumulation rates of 87-218 t/km/year in non-permafrost soils. Erosion and accumulation were relatively low and related to the vegetation community. The long-term (Be) soil redistribution rates (erosion rates up to 49 t/km/year and accumulation rates up to 4 t/km/year) were low with no significant differences between permafrost and non-permafrost sites. The δC signature indicated soil disturbances in permafrost and non-permafrost soils compared to the reference site. Conclusions: Our results highlight that soil redistribution rates have increased during the last few decades. However, whether the higher medium-term erosion rates obtained for the last decades are the result of the ongoing climate warming and related accelerated soil erosion or if other factors (e.g. measurement uncertainties) have been responsible for such an increase could not fully be clarified. [ABSTRACT FROM AUTHOR]

Abstract: High-mountain soils develop in particularly sensitive environments. Consequently, deciphering and predicting what drives the rates of soil formation in such environments are a major challenge. In terms of soil production or formation from chemical weathering, the predominating perception for high-mountain soils and cold environments is often that the chemical weathering ‘portion’ of soil development is temperature-inhibited, often to the point of non-occurrence. Several concepts exist to determine long-term rates of soil formation and development. We present three different approaches: (1) quantification of soil formation from minimally eroded soils of known age using chronosequences (known surface age and soil thickness — SAST), (2) determination of soil residence times (SRT) and production rates through chemical weathering using (un)stable isotopes (e.g. 230Th/234U activity ratios), and (3) a steady state approach using cosmogenic isotopes (e.g. 10Be). For each method, data from different climate zones, and particularly from high-mountaINS (alpine environment), are compared. The SAST and steady state approach give quite similar results for alpine environments (European Alps and the Wind River Range (Rocky Mountains, USA)). Using the SRT approach, soil formation rates in mountain areas (but having a temperate climate) do not differ greatly from the SAST and steady state approaches. Independent of the chosen approach, the results seem moderately comparable. Soil formation rates in high-mountain areas (alpine climate) range from very low to extremely high values and show a clear decreasing tendency with time. Very young soils have up to 3–4 orders of magnitude higher rates of development than old soils (105 to 106 yr). This apparently is a result of kinetic limits on weathering in regions having young surfaces and supply limits to weathering on old surfaces. Due to the requirement for chemical weathering to occur, soil production rates cannot be infinitely high. Consequently, a speed limit must exist. In the literature, this limit has been set at about 320 to 450t/km2/a. Our results from the SAST approach show, however, that in alpine areas soil formation easily reaches rates of up to 800–2000t/km2/a. These data are consistent with previous studies in mountain regions demonstrating that particularly young soils intensively weather, even under continuous seasonal snowpack and, thus, that the concept of ‘temperature-controlled’ soil development (soil-forming intervals) in alpine regions must be reconsidered. [Copyright &y& Elsevier]

Abstract: Rock glaciers contain valuable information about the spatial and temporal distribution of permafrost. The wide distribution of these landforms in high mountains promotes them as useful archives for the deciphering of the environmental conditions during their formation and evolution. However, age constraints are needed to unravel the palaeoclimatic context of rock glaciers, but numerical dating is difficult. Here, we present a case study assessing the potential of luminescence techniques (OSL, IRSL) to date the inner sand-rich layer of active rock glaciers. We focus on the signal properties and the resetting of the signal prior to deposition by investigating single grains. While most quartz shows low signal intensities and problematic luminescence characteristics, K-feldspar exhibits much brighter and well-performing signals. Most signals from plagioclases do not show suitable properties. Luminescence signals far below saturation indicate distinct but differential bleaching. The finite mixture model was used to determine the prominent populations in the equivalent dose distributions. The luminescence ages represent travel times of grains since incorporation into the rock glacier and hence, minimum ages of rock glacier formation. Luminescence ages between 3 ka and 8 ka for three rock glaciers from the Upper Engadine and Albula region (Swiss Alps) agree well with independent age estimates from relative and semi-quantitative approaches. Therefore, luminescence seems to have the potential of revealing age constraints about processes related to the formation of rock glaciers, but further investigations are required for solving some of the problems remaining and reducing the dating uncertainties. [Copyright &y& Elsevier]

Soil development and erosion are important and opposing processes in the evolution of high-mountainous landscapes, though their dynamics are not fully understood. We compared soil development between a calcareous and a siliceous chronosequence in the central Swiss Alps at high altitudes, which both cover soil formation over the Holocene. We calculated element mass balances, long-term erosion rates based on meteoric 10Be and we determined the rates of soil formation. We also analyzed the shifts in the mineralogical composition, weathering indices, the particle size distribution, carbon stocks and oxalate extractable Fe, Al, and Mn. The siliceous soils had high chemical weathering rates at the early stage of soil formation that strongly decreased after a few millennia. The development of calcareous soil was characterized by high carbonate losses and a shift to finer soil texture. Soil erosion hampered the upbuilding of soil horizons in the early stages of soil development, which led to a delay in soil and vegetation development. This study shows how soil formation drivers change over time. In the early stages of soil development, the parent material predominantly drives soil formation while at later stages the vegetation becomes more dominant as it influences surface stability, hydrological pathways, and chemical weathering that determine water drainage and retention. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this work was to detect imprints on soil properties from former Islamic land use (9th to 11th century) using a multi-method, soil-chemical approach. Four soil profiles (with buried horizons) found in the vicinities of former Islamic settlements in Sicily were analysed for phosphorus (total, organic and inorganic), nitrogen (total, NO3 − and NH4 +), carbon compounds (δ13C, lipids, polycyclic aromatic hydrocarbons (PAH) and functional groups), physical and chemical C-fractions and the state of soil weathering. Two soil profiles contained ceramic sherds from the Islamic period. Inorganic nitrogen forms, phosphorous and the PAH content indicated strong impacts from traditional agriculture and/or burning. Radiocarbon dating of soil organic carbon (SOC) fractions from buried horizons showed that distinct changes must have occurred during the Islamic epoch. The isotopic composition of SOC indicated that land use was probably different in earlier times. C4 plant cultivation was expected but surprisingly lipid analyses did not confirm this. A high amount of aliphates and low C/N ratio indicated a good, long-term SOC stabilisation under the native conditions combined with Islamic land use. The irrigation of the soils probably increased the production of weakly-crystalline Fe forms that helped to stabilise SOC. The multi-method approach was very helpful in deciphering human-induced processes. Although a full proof for each parameter is not given, former Islamic land-use seems to have distinctly affected the soils – not only locally but probably also in other areas of Sicily, Northern Africa, Near East and Iberian Peninsula. [Copyright &y& Elsevier]

Grasslands store substantial amounts of carbon in the form of organic matter in soil and roots. At high latitudes and elevation, turnover of these materials is slow due to various interacting biotic and abiotic constraints. Reliable estimates on the future of belowground carbon storage in cold grassland soils thus require quantitative understanding of these factors. We studied carbon turnover of roots, labile coarse particulate organic matter (cPOM) and older non-cPOM along a natural pH gradient (3.9-5.9) in a subalpine grassland by utilizing soil fractionation and radiocarbon dating. Soil carbon stocks and root biomass, turnover, and decomposability did not scale with soil pH whereas mean residence times of both soil organic matter fractions significantly increased with declining pH. The effect was twice as strong for non-cPOM, which was also stronger enriched in N at low pH. Considering roots as important precursors for cPOM, the weaker soil pH effect on cPOM turnover may have been driven by comparably high root pH values. At pH < 5, long non-cPOM mean residence times were probably related to pH dependent changes in substrate availability. Differences in turnover along the pH gradient were not reflected in soil carbon stocks because aboveground productivity was lower under acidic conditions and, in turn, higher inputs from aboveground plant residues compensated for faster soil carbon turnover at less acidic pH. In summary, the study provides evidence for a strong and differential regulatory role of pH on the turnover of soil organic matter that needs consideration in studies aiming to quantify effects of changing environmental conditions on belowground carbon storage. [ABSTRACT FROM AUTHOR]

Abstract: Chemical weathering of rocks or sediments is extremely important for the generation of soils, for the evolution of landscape, and as a main source of inorganic nutrients for plant growth and therefore for life. Temporal trends in weathering mechanisms, plant succession and nutrients availability in cold environments can be successfully studied in soil chronosequences along a glacier forefield. In the present paper, this was carried out in the pro-glacial area of Morteratsch. Different forms of phosphorous in the soil, stream and spring water chemistry were investigated. Apatite constitutes the main source of P, but it occurs only as a minor accessory mineral phase in the granitic/gneiss parent material. The identification of apatite was performed using SEM-EDX and cathodoluminescence. Water chemistry data indicated some calcite dissolution at the earliest phase of exposure, pyrite and — on older surfaces increasingly — feldspar weathering. Apatite also seemed to contribute to Ca which is leached from the soils. The concentrations of dissolved P in the stream and spring waters were, however, extremely low (only a few μg P/l). In the topsoil, the total stocks of P showed a slight decrease with time. Losses were rather difficult to detect even though the water fluxes through the soils and discharges are relatively high. Soil organic P is almost identical to the EDTA-extractable fraction. In an 11.5ky-old soil outside the glacier forefield the concentration and proportions of organic P, EDTA-extractable P and inorganic P forms did not differ that much from the oldest soils (max. 150years) of the glacier forefield. In the bulk soil, about 78% of total P was transformed into an organic form (40% already after 150years) and, in the fine earth, about 81% (40–70% after about 150years of soil evolution). Thus the P transformation reactions are shown to be very rapid, occur predominantly in the early phase of soil formation, and could be best described by an exponential decay model. [Copyright &y& Elsevier]

Abstract: Using published and new chronosequence datasets from the European Alps and the Wind River Range (Rocky Mountains, USA), we report for the first time a chronosequence of more than 1Ma for soil organic carbon, nitrogen and organic matter (SOM) fractions from alpine soils. The investigated parameters include total carbon and nitrogen as well as the stable (resistant to H2O2 oxidation) C and N fractions. Time trends were analysed and are reported on the basis of stocks and concentrations. The accumulation rates of C and N strongly decreased with increasing soil age. Differences in trends between the European Alps and the Wind River Range might be attributed to the factor climate. For the drier Wind River Range, an asymptotic value of about 15kgC m−2 was reached after about 15ky while an asymptotic value of 20–25kgC m−2 was measured for the moister European Alps after about 3ky. The difference in N stocks between the two regions was less obvious. For both areas, N was in the range of 0.5–2kgN m−2. Using the exponential decay model, a steady state of C and N (stable and total) concentrations in the topsoil seemed to be reached after <1ky (Alps) and 10ky (Wind River Range). The retardation effect observed for the Wind River Range could probably be due to aeolian influx. For both areas, the asymptotic value of the stable fraction of C and N was in the range of 1–3kgC m−2 and 0.2–0.4kgN m−2, respectively. The stable organic fraction often has an age close to the age of the soils and consequently can reach thousands of years. The relative proportion of N and amides was higher in the stable organic fraction compared to the bulk soil. The sequestration rates of org. C and N in soils of the European Alps and the Wind River Range can reach very high values in very young soils whereas in old soils sequestration rates are several orders of magnitude lower. Old soils often integrate several cold and warm phases and different vegetation types. Nonetheless, the factor Time seems to be very dominant and covers the track of other factors in old soils. [Copyright &y& Elsevier]

Gruber, S., Egli, M., Gärtner-Roer, I. and Hoelzle, M., 2012. Preface: The mountain cryosphere - a holistic view on processes and their interactions. Geografiska Annaler: Series A, Physical Geography, ••, ••-••. doi:10.1111/j.1468-0459.2012.00468.x [ABSTRACT FROM AUTHOR]

Abstract: Charcoal fragments in soils are useful to reconstruct past vegetation because the level of preservation is often good enough to determine the tree genus. All forest ecosystems have the potential to burn as a result of naturally occurring or human-induced fires. Forest fires are coupled to climate and are a not-negligible factor of pedogenesis in Mediterranean areas, where they occur frequently. Furthermore, soil organic matter (SOM) is prone to undergo peculiar changes due to forest fires, both in terms of quantity and quality. A soil sequence along an elevational gradient ranging from Mediterranean to subalpine climate zones on slopes of Mt. Etna (Sicily, Italy) was investigated in respect of soil organic C and charcoal. The amount of charcoal and the identification of charred species gave an indication of the fire frequency and vegetation changes that have occurred in the past. The distribution into labile and stable organic fractions provided insight into the stabilisation and turnover mechanisms of SOM. The stable organic matter fraction was measured as the residue of a H2O2 treatment. The soils along the altitudinal sequence are variations of Vitric Andosols that developed on a single trachy-basaltic lava flow having an age of 10–15ky BP. Maquis vegetation dominates at the lower sites of the toposequence, followed by oak- and chestnut-forests at mid elevations, and pine-forest at the highest-elevated sites. Charcoals are older at higher elevations (ages of up to 1.5ky cal BP). Here, the vegetation type has not changed over the last >1000years, as all charcoal pieces were identified as Pinus nigra. Charred material at the lower sites could be identified as particles of deciduous shrubs, Quercus, Castanea sativa, Lonicera implexa and Cytisus spp. with mostly a modern age up to about 300y cal BP. A similar finding was obtained for the stable (H2O2 resistant) SOM. Very high ages for this fraction were found at the highest elevations where it had an age of up to 8.2ky BP — an age that is close to the start of soil formation. At the lower sites, where frequent bush fires often destroyed a part of the stable fraction, the stable SOM fraction had a maximum age of 1ky. The studied soils have recorded the signals of the interrelated factors fire frequency, climatic effects and vegetation whose role cannot always be clearly distinguished. With decreasing altitude and with a warmer climate, vegetation changes and fire frequency, org. C and especially nitrogen abundance and the amount of labile SOM increases. At the lower sites, charcoal particles reflect the more recent vegetation probably because the repeated fires here hindered their preservation. Our findings hence suggest that a high fire frequency is a powerful rejuvenating factor for soil organic matter, removing part of the old SOM and promoting plant recolonisation that is a source of young SOM. Fire frequency and intensity on Mt. Etna is, however, moderate enough even at the lowest altitudes for the organic matter pool to be high and not depleted. [Copyright &y& Elsevier]

Abstract: Proglacial areas in the Alps usually cover a time span of deglaciation of about 150years (time since the end of the ‘Little Ice Age’ in the 1850s). In these proglacial areas soils have started to develop. Due to the continuous retreat of the Morteratsch glacier (Swiss Alps), the corresponding proglacial area offers a continuous time sequence from 0 to 150year-old surfaces. Furthermore, an optimal digital dataset about the development of vegetation and soils is available for this area. The soils have been developing on glacial till having a granitoidic character. We investigated the clay mineral assemblage at 35 sites within the glacier forefield. Smectite can be used as a proxy for weathering intensity in these environments. In the proglacial area, the smectite concentration in the topsoil steadily increased with time of weathering; however, this development displayed a strongly scattered trend. The complex interplay of biological, physical, and chemical processes in pedogenesis and clay mineral evolution limits our ability to predict and interpret landscape dynamics. We consequently tried to analyse the role of topographic and vegetation modifications on the smectite content. Sites not or only slightly prone to erosion (flattening slope ridge, steepening slope ridge) or flat morphology promoted the formation of smectite. In addition, the texture of the soil material influenced soil moisture and hence the degree of weathering and the development of vegetation. Although vegetation is not a fully independent factor, because it is interrelated to the surrounding environmental conditions, it seemed to exert its influence on weathering and, consequently, the formation of smectite. Green alder stands and grass heath, where moister soils develop that have a finer texture or where more organic acids are produced, were correlated with a higher smectite content. Humus forms serve as a proxy for the soil biota and soil organic matter composition. At sites having a Eumoder and a higher soil organic matter content, the smectite concentration was elevated. At these sites, the production of chelating compounds or organic acids in the soil is believed to promote the development of smectites via an intermediate stage of hydroxy-interlayered minerals and the subsequent removal of the hydroxide polymers. In this work we have demonstrated that the topographic signature and the effect of vegetation on the formation of smectite and consequent weathering are pervasive. Our results will serve as a basis for further spatio-temporal modelling. [Copyright &y& Elsevier]

Abstract: Global warming leads to the melting of ice caps and glaciers and, consequently, the exposure of new areas of land to the atmosphere and weathering. These areas usually have a high reactivity to both biotic and abiotic changes. Proglacial areas in the Alps usually have a deglaciation time span of around 150years (time since the end of the “Little Ice Age” in the 1850''s). We investigated a chronosequence of very young soils in the proglacial area Morteratsch (Swiss Alps) to derive time-trends of soil organic matter accumulation and evolution. Total organic C and N contents, C and N contents of the various organic matter (OM) density fractions and of the labile (oxidised by H2O2) and stable (H2O2-resistant) fractions were measured. Further characterisation of OM and the various fractions was performed using Diffuse Reflection Infrared Fourier Transform (DRIFT). Soil organic matter has been accumulated over 150years at very high rates, values lay between 7 and 36g C/m2/year. This led to a soil organic matter abundance of about 1–5.5kg C/m2 after 140years. Even at the start of soil formation, a very stable fraction of soil organic matter was detectable. Stable organic matter (resistant to the H2O2 treatment) comprised about 6% of the total soil organic carbon and 10% of the total nitrogen. At the start of soil formation, a very high proportion of soil organic matter was present in the density fractions <1.6g/cm3. After about 140years, 15% of soil organic carbon and 35–40% of the nitrogen was already present in the highest density fraction (>2g/cm3). With time, the quality of soil organic matter changed: a decrease of hydrophobicity, an increase in aromatic compounds in the bulk soil and a decrease in phenolic functional groups in the heaviest density fraction were detectable with increasing age. In general, stable organic matter as well as the density fraction >2g/cm3 had a low C/N ratio and were enriched in proteinaceous materials. The adsorption of proteinaceous materials points to a strong organo-mineral association. This process has existed since the very beginning of soil formation. [Copyright &y& Elsevier]

Abstract: To exploit natural sedimentary archives and geomorphic landforms it is necessary to date them first. Landscape evolution of Alpine areas is often strongly related to the activities of glaciers in the Pleistocene and Holocene. At sites where no organic matter for radiocarbon dating exists and where suitable boulders for surface exposure dating (using in situ produced cosmogenic nuclides) are absent, dating of soils could give information about the timing of landscape evolution. This paper explores the applicability of soil dating using the inventory of meteoric 10Be in Alpine soils. For this purpose, a set of 6 soil profiles in the Swiss and Italian Alps was investigated. The surface at these sites had already been dated (using the radiocarbon technique or the surface exposure determination using in situ produced 10Be). Consequently, a direct comparison of the ages of the soils using meteoric 10Be and other dating techniques was made possible. The estimation of 10Be deposition rates is subject to severe limitations and strongly influences the obtained results. We tested three scenarios using a) the meteoric 10Be deposition rates as a function of the annual precipitation rate, b) a constant 10Be input for the Central Alps, and c) as b) but assuming a pre-exposure of the parent material. The obtained ages that are based on the 10Be inventory in soils and on scenario a) for the 10Be input agreed reasonably well with the age using surface exposure or radiocarbon dating. The ages obtained from soils using scenario b) produced ages that were mostly too old whereas the approach using scenario c) seemed to yield better results than scenario b). Erosion calculations can, in theory, be performed using the 10Be inventory and 10Be deposition rates. An erosion estimation was possible using scenario a) and c), but not using b). The calculated erosion rates using these scenarios seemed to be plausible with values in the range of 0–57mm/ky. The dating of soils using 10Be has several potential error sources. Analytical errors as well as errors from other parameters such as bulk soil density and soil skeleton content have to be taken into account. The error range was from 8 up to 21%. Furthermore, uncertainties in estimating 10Be deposition rates substantially influence the calculated ages. Relative age estimates and, under optimal conditions, absolute dating can be carried out. Age determination of Alpine soils using 10Be gives another possibility to date surfaces when other methods fail or are not possible at all. It is, however, not straightforward, quite laborious and may consequently have some distinct limitations. [Copyright &y& Elsevier]

Abstract: Investigations in Alpine soils indicate that mineral weathering is much faster in ‘young’ soils (<1000yr) than in ‘old’ soils (∼10,000yr). However, little is known about the initial stages of weathering and soil formation, i.e. during the first decades of soil genesis. In this study we investigated rock-forming minerals weathering at very early stages of soil formation. Due to the continuous retreat of the Morteratsch glacier (Upper Engadine, Swiss Alps), the proglacial area offers a full time sequence from 0 to 150yr old surfaces. A low slope and the absence of glacier which might have interrupted soil formation processes, contributed to the choice of the Morteratsch proglacial valley for this case study. The area is well documented regarding vegetation and soils. The tectonic unit is the Bernina-crystalline, which is mainly constituted of granitoid rocks. Consequently, the glacial till has an acidic character. Mineralogical measurements were carried out on the soil fraction <2mm using XRD and DRIFT for qualitative and quantitative phase analysis. In addition, chemical analyses of the stream water from the main channel, tributaries and of rainwater were performed with a special focus on Ca/Sr and Sr isotope ratios (87Sr/86Sr). Furthermore, the accumulation of organic matter within the time sequence and physical soil properties were measured. Decreasing grain size with time shows active physical weathering processes. Soil organic matter has been accumulated during 150yr at very high rates. Special emphasis has been given to chemical weathering and to the formation and transformation mechanisms of minerals. Of special interest were biotite, chlorite, epidote, plagioclase and calcite. Biotite has been continuously transformed into illite-like components. Within 150yr, the concentration of epidote significantly decreased. The high Ca/Sr as well as 87Sr/86Sr ratios in the stream and spring waters confirmed that Ca bearing minerals are weathering and transforming at very high rates in the proglacial area. Also in cryic, ice-free environments, chemical weathering rates are high leading to the formation and transformation of minerals. Disseminated calcite in granitoid rocks, not confined to sedimentary carbonate rocks, also plays a role in subglacial environments. It is, however, not known for how long such an influence is significant and measurable. The high Ca/Na and Ca/Sr ratio in the stream and tributary waters showed that calcite contributes to the supply of soluble Ca, although the ion activity product calculations clearly demonstrated that the waters were undersaturated with respect to this mineral. [Copyright &y& Elsevier]

Subalpine and Alpine soils in Val di Sole (Trentino, Italy) have been investigated in order to reconstruct vegetation changes and human impact during the Holocene period. Archaeological findings have demonstrated that Alpine sites have been populated since pre-historical times. Humans have had a great impact on the natural landscape evolution. One of the most-used tools has been fire. The use of fire has enabled the landscape to be cleared to provide new pastures for grazing and also to allow it to be used for agricultural purposes. The 14C dating of charcoal fragments found in subalpine and Alpine soils provide information about the type of vegetation, fires, human impact and soil formation throughout the Holocene. The degree of podzolisation indicates weathering effects and provides information about the stability of the surfaces. According to our results, a quick forest expansion establishment phase must have occurred shortly after the Lateglacial around 10 500 cal. BP. Pinus sylvestris, Pinus mugo as well as Larix decidua established in the investigation area in that period. Picea abies had not yet migrated into this region at the transition to the Boreal (around 9000 cal. BP). The vegetation of the investigated area has not substantially changed during the last 10 000 years. Pinus mugo was more widespread in some areas during the Older Atlanticum, and the treeline was about 150 m higher at the end of the Younger Dryas than today. Some other sites were most probably used as pasture during the Bronze Age and later abandoned, leading to a natural reforestation. In the investigated area 13 fire events in the past 10 700 years have been recognised, and seven of them can reasonably be attributed to human origin. [ABSTRACT FROM AUTHOR]

Abstract: The present work focuses on the subalpine range of the Italian Alps to determine the influence of aspect and consequently climate on soil humus properties and chemistry. This was done by comparing soils developing in north- and south-facing sites on siliceous parent material. The soils were investigated with respect to the total organic C and N content, C and N contents of organic matter (OM) density fractions and of labile (oxidised by H2O2) and stable (H2O2-resistant) fractions. Further characterisation of OM and the different fractions was performed with Diffuse Reflection Infrared Fourier Transform (DRIFT), Scanning Electron Microscopy/Electron Diffuse Scattering (SEM/EDS) and radiocarbon dating. The soils at north-facing slopes had a higher OM content. Density measurements and the H2O2 fractionation proved that this higher content was primarily due to a more pronounced accumulation of weakly degraded, labile organic materials when compared to the south-facing slopes. Independent of the sites, a large part of OM (around 50% of OM) was fixed in the densest fraction (>2 g/cm3) which correlated well with the abundance of the H2O2-resistant fraction. The 14C ages of the latter were up to 17,000 years, reflecting the presence of stable, refractory OM and the effectiveness of organo-mineral interactions in protecting OM from decay. Podzolisation has been more intense at north-facing sites. Due to the accumulation of weakly degraded OM, eluviation of Fe and Al is strongly enhanced. High-mountain ecosystems like the Alps are very sensitive to changing environmental conditions such as global warming. Especially at cooler sites, the obtained results suggest that a warmer climate, and thus more favourable conditions for biological activity, will lead in the short- to mid-term to an increased loss of accumulated, weakly degraded OM. [Copyright &y& Elsevier]

• Newly constructed Mediterranean soils have a very high carbon sequestration potential. • After 48 years, about 12 kg org. C m−2 were accumulated. • The org. C sequestration rates remain high until about 50–100 years. • Chemical weathering contributes to C consumption but is difficult to be quantified. • With time, macroporosity decreased to about half of its original value. The increasing atmospheric CO 2 concentration is a consequence of human activities leading to severe environmental deteriorations. Techniques are thus needed to sequester and reduce atmospheric carbon. One of the proposed techniques is the transformation or construction of new soils into which more organic carbon can be sequestered and CO 2 be consumed by increased weathering. By using a chronosequence of new and transformed soils on crushed limestone (0–48 years) in a Mediterranean area (Sicily), we tried to quantify the amount of organic carbon that could be additionally sequestered and to derive the corresponding rates. A further aim was to trace chemical weathering and related CO 2 consumption and the evolution of macropores that are relevant for water infiltration and plant nutrition. Owing to the irrigation of the table grape cultivation, the transformed soils developed fast. After about 48 years, the organic C stocks were near 12 kg m−2. The average org. C sequestration rates varied between 68 and 288 g m−2 yr−1. The C accumulation rates in the transformed soils are very high at the beginning and tend to decrease over (modelled) longer time scales. Over these 48 years, a substantial amount of carbonate was leached and reprecipitated as secondary carbonates. The proportion of secondary carbonates on the total inorganic carbon was up to 50%. Main mineralogical changes included the formation of interstratified clay minerals, the decrease of mica and increase of chloritic components as well as goethite. The atmospheric CO 2 consumption due to silicate weathering was in the range of about 44–72 g C m−2 yr−1. Due to the high variability, the contribution of chemical weathering to CO 2 consumption represents only an estimate. When summing up organic C sequestration and CO 2 consumption by silicate weathering, rates in the order of 110–360 g C m−2 yr−1 are obtained. These are very high values. We estimated that high sequestration and CO 2 consumption rates are maintained for about 50–100 years after soil transformation. The macropore volume decreased over the observed time span to half (from roughly 10 to 5 %). The transformation of soils may even amend their characteristics and increase agricultural production. Due to the relatively sandy character, enough macropores were present and no substantial compaction of the soils occurred. However, great caution has to be taken as such measures can trigger deterioration of both soil ecosystem services and soil quality. [ABSTRACT FROM AUTHOR]

Abstract: Soil organic matter (SOM) may give precious information about the age of soil landscapes and, thus, can contribute to decipher geomorphic surface dynamics. We tested five methods of isolating the oldest possible stable organic matter of 2 soil profiles developed on a Pleistocene morainic paragneiss substratum in an Alpine environment in northern Italy. Before and after the individual treatments, the organic fraction was dated with 14C. The first two methods consist of the oxidation of organic matter with 10% hypochlorite (NaOCl), followed by dissolution of minerals with 10% hydrofluoric acid (HF) or 1 M aqua regia. Methods 3 and 4 were similar to the first two but with a changed order of the treatments (chemical oxidation as the last step). Method 5 consisted only of a treatment with hydrogen peroxide (H2O2) for 7 days. Methods 1–4 enabled, in theory, the separation of labile, mineral-protected and recalcitrant SOM fractions. With method 5 only two different fractions can be discerned, i.e. a labile one and a stable one. The lowest ages for each soil were obtained with methods 1–3 (5176 and 8835 cal BP). Higher ages were obtained with method 4 (aqua regia and NaOCl). In general, methods 1–4 showed increasing ages with increasing soil depth. The H2O2 treatment, however, left behind an organic fraction with the highest ages of up to 17,000 cal BP in the topsoil and decreasing ages with soil depth. In general, the 14C ages of the treatment-resistant fraction increased in the order: untreated samples

Abstract: A weathering sequence with soils developing on volcanic, trachy-basaltic parent materials with ages ranging from 100–115,000 years in the Etna region served as the basis to analyse and calculate the accumulation and stabilisation mechanisms of soil organic matter (SOM), the transformation of pedogenic Fe and Al, the formation and transformation of clay minerals, the weathering indices and, by means of mass-balance calculations, net losses of the main elements. Although the soils were influenced by ash depositions during their development and the soil on the oldest lava flow developed to a great extent under a different climate, leaching of elements and mineral formation and transformation could still be measured. Leaching of major base cations coupled with a corresponding passive enrichment of Al or Fe was a main weathering mechanism and was especially pronounced in the early stages of soil formation due to mineral or glass weathering. With time, the weathering indexes (such as the (K+Ca)/Ti ratio) tend to an asymptotic value: chemical and mineralogical changes between 15,000 and 115,000 years in the A and B horizons were small. In contrast to this, the accumulation of newly formed ITM (imogolite type materials) and ferrihydrite showed a rather linear behaviour with time. Weathering consisted of the dissolution of primary minerals such as plagioclase, pyroxenes or olivine, the breakdown of volcanic glass and the formation of secondary minerals such as ITM and ferrihydrite. The main mineral transformations were volcanic glass ➔ imogolite ➔ kaolinite (clay fraction). In the most weathered horizons a very small amount of 2:1 clay minerals could be found that were probably liberated from the inner part of volcanic glass debris. The rate of formation and transformation of 2:1 clay minerals in the investigated soils was very low; no major changes could be observed even after 115,000 years of soil evolution. This can be explained by the addition of ash and the too low precipitation rates. In general, soil erosion played a subordinate role, except possibly for the oldest soils (115,000 years). The youngest soils with an age <2000 years had the highest accumulation rate of organic C (about 3.0 g C/m2/year). After about 15,000 years, the accumulation rate of organic C in the soils tended to zero. Soil organic carbon reached an asymptotic value with abundances close to 20 kg/m2 after about 20,000 years. In general, the preservation and stabilisation of SOM were due to poorly crystalline Al- and Fe-phases (pyrophosphate-extractable), kaolinite and the clay content. These parameters correlated well with the organic C. Imogolite-type material did not contribute significantly to the stabilisation of soil organic matter. [Copyright &y& Elsevier]

Abstract: The older forest type Quercetum–Betuletum (oak/birch; Q-type vegetation) in southern Switzerland and northern Italy was to a large extent replaced by chestnut forests (Castanea sativa; C-type vegetation) in roman times. When laurophylloid vegetation (L-type vegetation) invaded some of these chestnut systems during the last few decades, it caused detectable changes in organic chemistry. The invasion of the L-type vegetation was predominately due to increased winter temperatures. We tested whether these vegetation changes led to measurable long-term and short-term responses of the mineral matrix by comparing soils under Q-type with C-type vegetation (probing for long-term effects; >100–2000 years) and soils under C-type with L-type vegetation (short-term effects; a few decades). To do so, we examined soil characteristics including the dithionite-, oxalate- and pyrophosphate-extractable forms of Fe, Al and Si as well as the phyllosilicate mineralogy of the clay fraction with a pair-wise comparison procedure. On L-type patches, short-term changes resulted in higher contents of secondary, poorly crystalline Fe. The accumulation of pedogenetic Fe probably results from a lower availability of organic complexing moieties under L-type vegetation and thus leading to a reduced removal. As soil acidity did not change with the vegetation types, a strong effect of organic compounds on Fe and Al chemistry must be assumed. A correlation analysis confirmed that metal binding to organic matter was different between L-type stands (correlation of Fe and Al with organic matter was less significant) and C-type stands. The differences in clay phyllosilicate assemblage between the different vegetation sites were rather small. There was, however, a trend towards higher contents of hydroxy-interlayered vermiculite (HIV) under L-type vegetation when compared to C-type sites. It seems that Al-polymers fixation in interlayers of 2:1 clay minerals was increased or their removal hindered at sites having L-type vegetation. Changes in the long-term (response to C-type vegetation) were only measurable for the pyrophosphate-extractable Si content (formation of phytolithe?). The colonisation of laurophyllous species led in the short-term to significant alterations of the soil system that were even more pronounced than the long-term effect of chestnut on soil quality. [Copyright &y& Elsevier]

Dendrochronology has been applied around the world over decades to reconstruct historical geomorphological events and climatic conditions. Traditionally, this research has been conducted using trees (conifers as well as broad-leaved trees) but, in the last few decades, several shrub and dwarf shrub species have also been shown to be useful for dendrochronological purposes. This study assesses the potential of mountain avens (Dryas octopetala L.) to provide accurately dated information about past debris-flow events. The study site, the Marlt-Graben debris-fan, is located in South Tyrol (Italy). 119 shrubs from three debris-flow tracks were analyzed. The longest radius of each sample was measured and cross-dated to build two chronologies for each debris-flow track, one for each leveé. Correlations between these chronologies and precipitation and temperature data from five climate stations located in the proximity of the study site were calculated. The cross-dating procedure was complex, but a strict grouping of the samples, based on the specific leveés of the tracks, enabled the construction of mean chronologies for each of the individual slopes. Although the development of a mean chronology for the study area was unsuccessful, the cross-dated ages of the single shrubs allowed us to reconstruct debris-flow events by utilizing the minimum age method. The low climate correlations suggest that micro site conditions strongly influence the growth of this dwarf shrub. Although the results of this study suggest that Dryas octopetala may provide useful dendroecological information, additional information about its growth dynamics is required before this potential can be fully realized. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the author discusses various reports within the issue on topics including the soil weathering rates, short- to long-term erosion processes and the contributions of soil formation and landscape modeling over time and space.

Quantifying soil redistribution rates, including both erosion and deposition, is critical for understanding erosion processes, landscape evolution, land management strategies, and the carbon cycle. In the Northeast Pacific coastal temperate rainforest, the interaction of perhumid climate and dense coniferous forest tends to form Spodosols which are soils characterized by a subsurface accumulation of organic matter and iron and aluminum oxides, across a range of contrasting lithologies. Deep Spodosols are frequently found on steep backslopes (up to 60%) of colluvial deposits, where shallower soils would typically be expected. We hypothesized that deep Spodosols in Southeast Alaska indicate slope stability, exhibiting negligible soil redistribution rates and stable surfaces regardless of the lithology. Our objective was to quantify soil redistribution rates for Spodosols formed on steep slopes across a range of lithologies in hilly and mountainous areas of Juneau, AK. We used 239+240Pu isotopes to quantify soil erosion and deposition rates in Spodosols formed on colluvial deposits from tonalite, slate, metavolcanic rock, and phyllite. 239+240Pu measurements revealed negligible soil redistribution rates for all studied pedons, ranging from erosion rates of 0.51 t/ha/year to deposition rates up to 0.43 t/ha/year. No difference was detected between the hill and mountain landforms, further supporting the idea that Spodosols could indicate slope stability over decadal timescales across the region. Understanding the resilience of Spodosols to erosion processes in varied lithologies and landforms on steep slopes is paramount for making informed decisions regarding sustainable land use, landslide risk mitigation, and effective carbon sequestration strategies. [ABSTRACT FROM AUTHOR]

At mid-latitudes, the transition from the Pleistocene to the Holocene was characterised by distinct and partially abrupt climatic changes. Also during the Holocene, climatic perturbations, with sometimes cold-dry conditions, have occurred. How land surfaces and soil development processes in high-mountains respond to these climatic oscillations is so far only poorly known. We traced the responses of surfaces in the alpine settings of the Wind River Range (Wyoming, US) by using a large mire as natural archive. This enabled us to reconstruct environmental conditions and ecosystem changes during the Holocene in this montane area. Although adjacent moraine deposits display 10Be exposure ages from the Last Glacial Maximum up to MIS16 or even older, the accessible sediment deposits covered only the Holocene (via radiocarbon dating). By applying a geoforensic approach and deriving sedimentation rates, major climatic signals were detected. A higher deposition (and consequently erosion) rate and thus a higher rate of geomorphic activity was measured for the known cold periods 9.4–10.2 ka BP, 4.2 ka BP and 2.5 ka BP. During the LIA, especially rapid aggradation of organic matter organic matter took place here. Rates of chemical weathering and soil formation seem to have been relatively low until about 5–6 ka BP but have since increased during the Late Holocene. This would fit previous observations of increasing moisture conditions after the mid-Holocene aridity period. In contrast to several other studies, no clear signs of major disturbances (erosion, weathering) during the 8.2 ka event could be observed. Together with the low levels of chemical weathering found here, we do not see any evidence that the climate was more humid during this period. Compared to previous findings, more humid conditions seemed to have returned earlier, i.e. about 5 kyr BP. In general, this landscape displayed a patchy pattern of reaction to environmental changes, as all events were not recorded in each mire profile. • The moraine complex in the Wind River Range reflected MIS16 up to MIS2 ages. • Based on mire profiles, net erosion/deposition rates were traced for the last 11 ka. • Increased erosion and deposition rates were recorded at 9.4–10.2, 4.2 and 2.5 ka BP. • The landscape reacted in a rather "patchy" manner to climate changes. • No changes in rates of deposition are detected for the 8.2 ka cold event. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

Plutonium (Pu) isotopes are attracting an increasing interest among fallout radionuclides (FRN) for their suitability as soil erosion/deposition tracer. Most of the recent studies were carried out on permanent grasslands and some in coniferous forests. One usually assumes that no erosion occurs in forested areas. However, this paradigm might be challenged because forest soils of Northern Germany in a hummocky ground moraine landscape exhibit sometimes a very shallow thickness on crest positions (Calcaric Regosols) and buried soils on slope positions (buried Ah as indicator). The question consequently is: Are these on-going or ancient processes? Therefore, a technique is needed that enables the determination of recent erosional process and a possibility to relate it to more long-term soil changes.In the present study, we measured the 239+240Pu stocks in a small, forested catchment (deciduous trees) that is characterised by a hummocky terrain including a kettle hole ("Melzower Forst"). Together with soil development depths, 239+240Pu stocks were correlated to relief parameters, e.g. the topographic position index (TPI). The TPI compares the elevation of each grid cell in a DEM with the mean elevation of a neighbourhood defined by a circle of a certain radius, in our study of 25 m.We compared the 239+240Pu stocks of fifteen different profiles and their relative erosion/accumulation rates to the TPI. Moreover, we used several mathematical models to evaluate the Pu-data and to quantify the erosion rates for the last 55 years. Our results show a very high spatial variability of the 239+240Pu stocks, from 35 to 70 Bq/m2, and no relationship to the TPI as has been demonstrated for arable land. Low annual rainfall, spatially distributed interception and stem flow might explain the high variability of the 239+240Pu stocks, giving rise to a patchy input pattern. The missing relationship between TPI and 239+240Pu stocks however demonstrated that no or negligible soil erosion has occurred during the last 55 years. As the forest has been protected for several hundreds of years, anthropogenic activities and maybe also natural events during the medieval times or earlier seemed to have caused strong erosional events which led to the soil pattern observed. [ABSTRACT FROM AUTHOR]

Humus forms are a distinctive morphological indicator of soil organic matter decomposition. The spatial distribution of humus forms depends on environmental factors such as topography, climate and vegetation. In montane and subalpine forests, environmental influences show a high spatial heterogeneity, which is reflected by a high spatial variability of humus forms. This study aims at examining spatial patterns of humus forms and their dependence on the spatial scale in a high mountain forest environment (Val di Sole/Val di Rabbi, Trentino, Italian Alps). On the basis of the distributions of environmental covariates across the study area, we described humus forms at the local scale (six sampling sites), slope scale (60 sampling sites) and landscape scale (30 additional sampling sites). The local variability of humus forms was analyzed with regard to the ground cover type. At the slope and landscape scale, spatial patterns of humus forms were modeled applying random forests and ordinary kriging of the model residuals. The results indicate that the occurrence of the humus form classes Mull, Mullmoder, Moder, Amphi and Eroded Moder generally depends on the topographical position. Local-scale patterns are mostly related to micro-topography (local accumulation and erosion sites) and ground cover, whereas slope-scale patterns are mainly connected with slope exposure and elevation. Patterns at the landscape scale show a rather irregular distribution, as spatial models at this scale do not account for local to slope-scale variations of humus forms. Moreover, models at the slope scale perform distinctly better than at the landscape scale. In conclusion, the results of this study highlight that landscape-scale predictions of humus forms should be accompanied by local- and slope-scale studies in order to enhance the general understanding of humus form patterns. [ABSTRACT FROM AUTHOR]