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Mathematical–statistical problem on estimation of soil-forming processes. This paper raises a mathematical–statistical problem that finally can be found in any chronosequence of a specific Quaternary-based process (e.g. soil mass, clay content accumulation). The problem arises when interval-specific rates of a component f(t) are intended by dividing the stock by the given age t. The procedure implies that only an average specific rate is calculated in a linear form, for example when soil organic carbon often tends to an asymptotic end-value. For any other parameters (e.g. sedimentation rates, soil horizons thickness), the same holds true. The mathematical–statistical problem arises if the rates are derived using a linear calculation (individual stocks, f(t) divided by time, t) and then plotted as a function of time, in circumstances where there is no correlation between tand the components f(t). To illustrate this problem, we used a random generator function where the plot tversus f(t) are not correlated. We also give examples of the chronosequence approaches of soil organic carbon and soil mass, where, at a given point, the real specific rate corresponds to the slope (first derivative) of the obtained non-linear regression function. The random generator function for the plot tversus f(t) showed no significant relationship (R2= 0.0), but f(t)t−1and tshowed highly significant correlation (R2= 0.62). The error in calculating the component rate by dividing by time instead of using the derivative function when the processes are not linear ranged between 22% and > 500%. We conclude that non-independent variables plotted in a chronosequence can infer correlations even when they might not exist. Carefully observation is needed on the dataset when the time is involved, particularly in Quaternary-based studies, since the mass component not necessarily is related with time. Avoid in calculating the change of the mass component simply dividing by time, because an over- or under-estimation from real rate (obtained by derivative function) occurs when the process under study is not linear.

A soil sequence along an elevational gradient ranging from subtropical to subalpine climate zones in the Etna region (Sicily, southern Italy) was investigated with respect to organic C, kaolinite, and crystalline to noncrystalline Al and Fe phases. Special emphasis was given to the stabilization of soil organic carbon (SOC) and its interaction with the inorganic phases. The soils were variations of Vitric Andosols that developed on a trachy-basaltic lava flow with an age of 15,000 years. Two main vegetation systems dominated the sites at the lower sites, it was mainly maquis vegetation and, at the higher elevated sites, predominantly coniferous forest. The concentration of SOC in the topsoil, the SOC stocks in the profiles, the humus fractions such as humic and fulvic acids, functional groups and substances of organic matter, imogolite-type materials (ITM), and oxyhydroxides were found to be strongly related to elevation and, thus, climate (precipitation and temperature) and vegetation. The C/N ratio in the topsoil was especially indicative of the vegetation type. The amount of SOC, ITM, and crystalline Fe oxyhydroxides decreased with increasing altitude. Weathering, as related to the proportion of crystalline Fe-oxyhydroxides or the kaolinite concentration in the clay fraction, seemed to be greater at the lower elevated sites. At these sites, maquis vegetation led to a higher accumulation of SOC as compared with the coniferous trees at the higher sites. Fire activity, as indicated by aromatic compounds in the humic acids and by the presence of charcoal in the soil, has most probably influenced several important soil processes. The identification and radiocarbon dating of charcoal revealed evidence that repeated bush fires had played a significant role in soil formation. The better stabilization of SOC at lower altitudes might be due to the specific climatic conditions with a more pronounced change in periods of humidity alternating with periods of droughts and resultant fire activity. The positive correlation between mean annual temperature and SOC content supports such a hypothesis. The climate- and vegetation-dependent stabilization of organic matter in the soil can be ascribed to the proportion of aromatics in the humic acids, to the presence of noncrystalline Al and Fe phases, to the kaolinite concentration, to the amount of clay, and to a lesser extent to the silt fraction.

ABSTRACTClimate change due to anthropogenic emissions of greenhouse gases is predicted to increase the average surface temperature. The most evident soil changes in the Alps will occur in proglacial areas where already existing young soils (with an age in most cases of up to 150 years) will continuously develop and new soils will form due to glacier retreat. Based on existing soil chronosequence data and statistical analyses in the proglacial area Morteratsch (Switzerland), the present-day state of the soils as well as their future development in the next 100 years in the existing and new proglacial area has been modeled taking the retreat of the glacier into consideration. The present-day as well as the future soil distribution was modeled using a probabilistic approach. Several soil characteristics have been modeled such as the pH value, the skeleton content, and the soil depth relevant to plant growth. To model soil properties in a future proglacial area (that is now covered by ice), the glacier-bed morphology had to be modeled. The calculations were performed using the cubic Non-Uniform Rational B-Spline (NURBS) curve to parameterize the course of a branch in flow direction. With the help of the ice cap and relief factor the thickness of the glacier was modeled. Climate change was introduced numerically by changing the mass balance of the glacier. For the area of interest a temperature increase of +1.6°C by the year 2050 and +3°C by the year 2100 can be assumed (according to the scenario A1B of IPCC). In the upper part of the proglacial area mostly Skeletic/Lithic Leptosols and Humi-Skeletic Leptosols will be found. In flat parts close to the main river, additional Fluvisols will develop. A considerable part of the upper proglacial area does not have any soil cover. Lithic/Skeletic to Humi-Skeletic Leptosols are modeled on the young lateral moraines. Chronosequences were vital to make any (4D) predictions of soil evolution in the proglacial area. The statistically and probabilistically based model also had, however, its weaknesses. The problems are related to the sediment properties in the glacier bed and the stability of new moraines.

ABSTRACTProglacial areas in the Alps usually cover a time span of deglaciation of about 150 years (time since the end of the “Little Ice Age” in the 1850s). In these proglacial areas soils have started to develop. In view of the foreseeable climate change, the time factor is of growing interest with respect to the landscape and consequently the soil development. We investigated soil changes (primarily on the basis of soil types) in the proglacial area Morteratsch (Swiss Alps) to derive time trends that can be used as a basis for spatial modeling. Differences in the soil development could be primarily interpreted in view of the time scale and topography (landscape shape, slope, aspect). Data was managed with GIS and regression analyses. Input data sets were the digital soil map, the glacial states, and the digital elevation model. The calculations were done raster based (GRID, 20 m resolution). After about 20 years the first signs of soil development could be found. Around 25% of the area of the valley floor is covered with weakly developed Skeletic/Lithic Leptosol after about 30 years of deglaciation. One hundred years of soil development led to a strong decrease of the Skeletic/Lithic Leptosol in favor of the Humi-Skeletic Leptosol and Ranker. Fluvisols and Cambisols play a subordinate role also after 100–150 years. Undisturbed and fast soil evolution was measured in flat positions and on slopes up to about 14°. In general, the various landforms also correlated well with soil evolution. One of the most surprising facts was that the weathering between south- and north-facing sites differed distinctly, with the north-facing sites having the higher weathering rates. Soil moisture seems to be a decisive factor in weathering. Thicker snow packs probably inhibit or reduce soil frost and allow larger fluxes of snowmelt water to infiltrate into already moist profiles. Slope, exposure and to a lesser extent also the landform determined the soil development: these influences could be quantified using regression analyses. These analyses serve as a basis for further spatio-temporal modeling.

We used the soil-core translocation method to investigate the effect of increased temperature on above- and below-ground phytomass and organic matter in cool alpine areas. The translocation of undisturbed soil cores from a high alpine site (2525 m a.s.l.) to an alpine site near the timberline (1895 m a.s.l.) achieved an effective artificial warming of 3.3 K. From a methodological point of view, the translocation of soil cores was performed successfully. Soil cores moved to a new site at the same altitude showed no change in above- and below-ground vegetation, bulk density, and soil skeleton. At both sites, soils were Haplic Podzols with a similar chemistry and clay mineralogy. At the lower elevation site, however, podzolization processes seemed to be more pronounced. As a consequence, the translocation of the soil cores probably led to a disturbance of the actual steady state that had been established after about 10,000–13,000 years of soil formation. This might have affected the adaptability of the vegetation system. Therefore, it cannot be fully excluded that the experimental design influenced the results. Translocation of soil cores from a very cool to a warmer site led to a distinct decrease in above-ground phytomass (about –45%) over the experimental period of two years. Below-ground phytomass significantly decreased (up to –50%) in the topsoil (0–5 cm) after artificial warming. Possible mechanisms are that roots reduced photosynthesis and hence C flow below-ground, a reduction of soil moisture that would have led to root death (not a very probable cause, however) or an abrupt change in the radiation duration and flux which affected root growth (also not very probable). Fast climate change exceeded the ability of the above-ground and below-ground phytomass to adapt quickly. Whether the decrease in phytomass was a short-term or a long-term response to climate warming remains uncertain. Based on a gradient study (climosequence at the same locality), we hypothesize that the decreased plant productivity might be a short-term effect.

Two soil sequences in northern Italy (Val di Fiemme and Val Genova) along an elevational gradient ranging from moderate (950 m a.s.l.) to high alpine (2440 m a.s.l.) climate zones were investigated with respect to element losses (Ca, Mg, K, Na, Fe, Al, Si, Mn) and development of clay minerals. Soils formed on paleo-rhyolitic parent material in Val di Fiemme and on tonalitic-granodioritic morainic material in Val Genova. All the soils have a similar age (~12,000 y) and have been classified as Podzols. The soils are very acid and the pH values tend to increase with decreasing altitude. Podzolization processes were most intense in the range of the subalpine forest up to the timberline (1400–1900 m above sea-level (a.s.l.)). Element leaching was greatest in this range and weathering rates decrease with both higher and lower altitudes. Due to the different lithologies and precipitations between the two valleys, the total amount of chemical weathering was slightly different, although the same trends with altitude could be observed. Imogolite-type materials (ITM) are generally of minor importance. Greater concentrations of ITM were observed in the Bhs or Bs horizons of the Episkeleti-Entic Podzols at the lower altitudes. Iron eluviation was similar in all Podzols while larger amounts of eluviated Al were detected in Val Genova. The pattern of smectite distribution along the climosequences had similarities to the trend of cation losses. The largest amount of low-charge expandable minerals seems to exist in the range of the subalpine forest up to the timberline. The development of clay minerals with a smaller layer charge was more advanced in Podzols on rhyolitic material where smectite could be detected in the Bhs and Bs horizon. Parent material influenced chemical weathering in the soils along the two climosequences and essentially determined the degree of weathering and the formation of clay minerals.

Clays of a soil sequence with five profiles in the Val Genova (northern Italy) along an elevation gradient with climate ranging from moderate to Alpine were investigated with XRD using several diagnostic treatments. Smectites developed in the surface horizons of podzolic soils either from chlorite through the removal of hydroxy interlayers or from mica, which weathers in a first step to regularly or irregularly interstratified clay minerals. Citrate treatment allowed the detection of low-charge expandable minerals in the Bhs or Bs horizons. Therefore, the reduction of the charge of 2:1 clay minerals occurred before the removal of hydroxy polymers by fulvic acids and low-weight organic acids. Due to the more intense podzolization process near the tree line, the d060region showed a temporal evolution of trioctahedral to dioctahedral mineral structures in the well developed Podzols. The pedogenic smectites of the E or Bhs horizons generally included one or several populations with various charges. In most cases, smectite was a heterogeneous mixture of montmorillonite and interstratified beidellite-montmorillonite. A pure beidellite phase could not be detected. The soils near the tree line, where weathering processes were most intense, had two main components: one with a charge >0.75, representing vermiculite-like minerals, and the other with a charge near 0.25, representing smectite. The charges of the beidellitic component and montmorillonite were almost equal. The higher the weathering state of the investigated soils, the lower was the layer charge of smectites.

Alpine soils are characterized by a high variability of chemical and physical parameters. The spatial inhomogeneity of a specific parcel must be regarded as a nuisance factor for representative soil sampling. The only way to reduce the effect of the variation between the samples is to combine several samples taken within an area of a few square meters. The presented approach shows how much soil material has to be taken in order to obtain representative values of soil properties such as soil density, the proportion of soil skeleton and fine earth, organic C, N, and the root content. Bulk density can be determined with an error ≤ 10% by sampling c. 6300 cm³ of soil within an area of 6 × 4.5 m for 0—20 cm sampling depth. With the same volume, the accuracy of soil skeleton measurement is ≤ 20%. In our case study, the determination of organic C in the fine earth of the whole soil profile needs a sample volume of 15,800 cm³ in order to reduce the error tolerance below ± 10%. In 0—20 cm soil depth, the error tolerance of ± 10% is achieved with c. 4000 cm³ for N and c. 6300 cm³ for organic C. Nearly 16,000 cm³ were needed to determine the soil root mass in the top 20 cm of a soil with an accuracy of ± 10%. In order to yield reasonable results, large sampling volumes are needed for soils in alpine areas. These volumes depend on the parameters to be investigated. Our investigation makes an initial attempt at optimizing the sampling strategy within an area of a few square meters in order to overcome this nuisance factor variation.

Alpine soils are characterized by a high variability of chemical and physical parameters. The spatial inhomogeneity of a specific parcel must be regarded as a nuisance factor for representative soil sampling. The only way to reduce the effect of the variation between the samples is to combine several samples taken within an area of a few square meters. The presented approach shows how much soil material has to be taken in order to obtain representative values of soil properties such as soil density, the proportion of soil skeleton and fine earth, organic C, N, and the root content. Bulk density can be determined with an error ≤ 10% by sampling c. 6300 cm³ of soil within an area of 6 × 4.5 m for 0—20 cm sampling depth. With the same volume, the accuracy of soil skeleton measurement is ≤ 20%. In our case study, the determination of organic C in the fine earth of the whole soil profile needs a sample volume of 15,800 cm³ in order to reduce the error tolerance below ± 10%. In 0—20 cm soil depth, the error tolerance of ± 10% is achieved with c. 4000 cm³ for N and c. 6300 cm³ for organic C. Nearly 16,000 cm³ were needed to determine the soil root mass in the top 20 cm of a soil with an accuracy of ± 10%. In order to yield reasonable results, large sampling volumes are needed for soils in alpine areas. These volumes depend on the parameters to be investigated. Our investigation makes an initial attempt at optimizing the sampling strategy within an area of a few square meters in order to overcome this nuisance factor variation.

Alpine soils are characterized by a high variability of chemical and physical parameters. The spatial inhomogeneity of a specific parcel must be regarded as a nuisance factor for representative soil sampling. The only way to reduce the effect of the variation between the samples is to combine several samples taken within an area of a few square meters. The presented approach shows how much soil material has to be taken in order to obtain representative values of soil properties such as soil density, the proportion of soil skeleton and fine earth, organic C, N, and the root content. Bulk density can be determined with an error ≤ 10% by sampling c. 6300 cm³ of soil within an area of 6 × 4.5 m for 0—20 cm sampling depth. With the same volume, the accuracy of soil skeleton measurement is ≤ 20%. In our case study, the determination of organic C in the fine earth of the whole soil profile needs a sample volume of 15,800 cm³ in order to reduce the error tolerance below ± 10%. In 0—20 cm soil depth, the error tolerance of ± 10% is achieved with c. 4000 cm³ for N and c. 6300 cm³ for organic C. Nearly 16,000 cm³ were needed to determine the soil root mass in the top 20 cm of a soil with an accuracy of ± 10%. In order to yield reasonable results, large sampling volumes are needed for soils in alpine areas. These volumes depend on the parameters to be investigated. Our investigation makes an initial attempt at optimizing the sampling strategy within an area of a few square meters in order to overcome this nuisance factor variation.

The distribution of vegetational organic matter above- and below-ground and its productivity was analyzed in an alpine area along a climosequence ranging from subalpine to alpine climates. Emphasis is placed on the quantification of carbon (C) and nitrogen (N) fixed in the above-ground and below-ground vegetation and its annual input. Annual C-input ranged from 17.9 to 60.2 g m^—2 year^—1 and the N-input from 0.74 to 2.48 g m^—2 year^—1. Above-ground phytomass and the annual production rate of organic matter showed a distinct correlation with the altitude and, thus, the climate. However, the measurement of the above-ground phytomass is bound to methodological problems: the commonly used harvesting method seems to underestimate the real situation. The harvesting method yielded in its average 100 to 300 g m^—2 phytomass which was 35—83% of the values obtained by the soil core method. Thus, the calculation of turnover times of above-ground vegetation greatly depends on the method used. Calculated turnover times based on the harvesting method did not correlate with the climate while a clear tendency of lower turnover times with increasing altitude could be observed using the soil core method. The amount of below-ground phytomass was in the range of 1880 to 2469 g m^—2 and the corresponding annual C-input (fixation in the roots) between 91.1 and 162 g m^—2 year^—1 and the N-input between 2.68 and 4.99 g m^—2 year^—1. The below-ground phytomass and its production rate in high alpine zones are of greater importance and exceed the above-ground ones. With increasing altitude, furthermore, the importance of the below-ground phytomass increases with respect to the biomass and to the C- and N-input. For high alpine areas, the phytomass is concentrated in the uppermost soil horizons. About 88.7 to 94.5% of the below-ground phytomass was found in the soil compartment 0-20 cm. The below-ground production rate of phytomass in alpine grassland is fundamental in order to calculate any C or N budgets and potential inputs to SOM: its neglection would introduce most significant errors in modeling any C or N cycles.

ABSTRACTAlpine ecosystems are vulnerable to ever-changing environmental conditions, leading to shifts in vegetation distribution and composition with implications on soil functionality and carbon (C) turnover. Although deadwood represents an important global C stock, scarce information is available on how slope exposure influences the wood-inhabiting microbiota throughout the decomposition process in an Alpine setting. We therefore evaluated the impact of slope exposure (north- vs. south-facing sites) on physicochemical and microbiological properties (microbial abundance based on real-time PCR: fungal 18S rRNA, dinitrogen reductase [nifH]; microbial biomass: double strand DNA; and microbial activity: hydrolytic enzyme activities of the main nutrient cycles) of Picea abieswood blocks and the underlying soil in a field experiment in the Italian Alps during a three-year period. Overall, a higher abundance of fungi and nitrogen-fixing bacteria was recorded in the soil at the north-facing site where cooler and moister conditions were observed. In contrast, no exposure effects were found for these two microbial groups in the wood blocks, while their abundance increased over time, accompanied by more acidic conditions with progressing decay. The impact of exposure was also enzyme specific and time dependent for both the P. abieswood blocks and the underlying soil.