ALBERT

Description: Borehole logging data (gamma ray, magnetic susceptibility) from the the Fucino Basin, hole F-4. Data as in Giaccio et al. (2019), doi:10.1016/j.quascirev.2019.106003

Description: Under the framework of the ANDRILL Southern McMurdo Sound (SMS) Project successful downhole experiments were conducted in the 1138.54 metre (m)-deep AND-2A borehole. Wireline logs successfully recorded were: magnetic susceptibility, spectral gamma ray, sonic velocity, borehole televiewer, neutron porosity, density, calliper, geochemistry, temperature and dipmeter. A resistivity tool and its backup both failed to operate, thus resistivity data were not collected. Due to hole conditions, logs were collected in several passes from the total depth at ~1138 metres below sea floor (mbsf) to ~230 mbsf, except for some intervals that were either inaccessible due to bridging or were shielded by the drill string. Furthermore, a Vertical Seismic Profile (VSP) was created from ~1000 mbsf up to the sea floor. The first hydraulic fracturing stress measurements in Antarctica were conducted in the interval 1000-1138 mbsf. This extensive data set will allow the SMS Science Team to reach some of the ambitious objectives of the SMS Project. Valuable contributions can be expected for the following topics: cyclicity and climate change, heat flux and fluid flow, seismic stratigraphy in the Victoria Land Basin, and structure and state of the modern crustal stress field.

Description: This paper aims to define the control exerted by geological setting on the evolution and segmentation of the Montaguto earth flow in Southern Italy. A detailed geological survey and multi-temporal maps were used to reconstruct the geological model of La Montagna Mt. and to quantify the evolution of the flow in terms of sediment pulse formation, movement direction and spatial change in earth-flow area. The spatial distribution of structural fabric of the mountainside was compared with (1) planar geometry of earth-flow source area, (2) orientation of strike-slip faults bounding the earth-flow moving core (i.e. movement direction) and (3) kinematic-zone position and extent. We infer that the evolution of the earth flow is controlled by geological structures and lithology. Moreover, the entire basal-slip surface is composed of newly formed basal-slip surface in the source area, and corresponds to pre-earth-flow topography downslope from the neck. Implications of our work are that (1) a detailed geological model of an unstable mountainside, combined with information about earth-flow spatial evolution, might be considered as a tool that allows the localization of areas of possible earth-flow enlargement and (2) geological structures constrain earth-flow movement, inducing a predictable seasonal behaviour in terms of movement direction.

Description: Earth Observing Systems are now routinely used to infer leaf-area index (LAI) given its significance in spatial aggregation of land-surface fluxes. Whether LAI is an appropriate scaling parameter for daytime growing-season energy budget, surface conductance ( G s ), water and light use efficiency and surface-atmosphere coupling of European boreal coniferous forests was explored using eddy-covariance (EC) energy and CO 2 fluxes. The observed scaling relations were then explained using a biophysical multi-layer soil-vegetation-atmosphere transfer model as well as by a bulk G s representation. The LAI variations significantly alter radiation regime, within canopy microclimate, sink/source distributions of CO 2 , H 2 O and heat, and forest floor fluxes. The contribution of forest floor to ecosystem scale energy exchange is shown to decrease asymptotically with increased LAI, as expected. Compared to other energy budget components, dry-canopy evapotranspiration (ET) was reasonably ‘conservative’ over the studied LAI range 0.5–7.0 m 2 m −2 . Both ET and G s experienced a minimum in the LAI range 1–2 m 2 m −2 caused by opposing non-proportional response of stomatally controlled transpiration and ‘free’ forest floor evaporation to changes in canopy density. The young forests had strongest coupling with the atmosphere while stomatal control of energy partitioning was strongest in relatively sparse (LAI ~2 m 2 m −2 ) pine stands growing on mineral soils. The data analysis and model results suggest that LAI may be an effective scaling parameter for net radiation and its partitioning but only in sparse stands (LAI 〈3 m 2 m −2 ). This finding emphasizes the significance of stand-replacing disturbances on the controls of surface energy exchange. In denser forests, any LAI -dependency varies with physiological traits such as light-saturated water use efficiency. The results suggest that incorporating species traits and site conditions are necessary when LAI is used in upscaling energy exchanges of boreal coniferous forests. This article is protected by copyright. All rights reserved.

Description: [1]  This study investigated patterns and controls of the seasonal and inter-annual variations in energy fluxes (i.e., sensible heat, H , and latent heat, λE ) and partitioning of the water budget (i.e., precipitation, P ; evapotranspiration, ET ; discharge, Q ; and soil water storage, ∆S ) over five years (2001–2005) in a boreal oligotrophic fen in northern Sweden based on continuous eddy covariance, water table level ( WTL ), and weir measurements. For the growing season (May 1 to September 31), the 5 year averages (± standard deviation) of the midday (10:00 to 14:00 h) Bowen ratio ( β , i.e., H / λE ) was 0.86 ± 0.08. Seasonal and inter-annual variability of β was mainly driven by λE which itself was strongly controlled by both weather (i.e., vapor pressure deficit, D , and net radiation, R n ) and physiological parameters (i.e., surface resistance). During the growing season, surface resistance largely exceeded aerodynamic resistance, which together with low mean values of the actual ET to potential ET ratio (0.55 ± 0.05) and Priestley-Taylor α (0.89) suggests significant physiological constrains on ET in this well-watered fen. Among the water budget components, the inter-annual variability of ET was lower (199 to 298 mm) compared to Q (225 to 752 mm), with each accounting on average for 34 and 65% of the ecosystem water loss, respectively. The fraction of P expended into ET was negatively correlated to P and positively to R n . Although a decrease in WTL caused a reduction of the surface conductance, the overall effect of WTL on ET was limited. Non-growing season (October 1 to April 30) fluxes of H , λE , and Q were significant representing on average −67%, 13%, and 61%, respectively, of their growing season sums (negative sign indicates opposite flux direction between the two seasons). Overall, our findings suggest that plant functional type composition, P and R n dynamics (i.e., amount and timing) were the major controls on the partitioning of the mire energy and water budgets. This has important implications for the regional climate as well as for ecosystem development, nutrient, and carbon dynamics.

Description: Our objective was to estimate and analyze the body-size distribution parameters of terrestrial mammal assemblages at different spatial scales, and to determine whether these parameters are controlled by local ecological processes or by larger-scale ones. Based on 93 local assemblages, plus the complete mammal assemblage from three continents (Africa, North, and South America), we estimated three key distribution parameters (diversity/size slope, skewness, and modal size) and compared the values to those expected if size distributions are mainly controlled by local interactions. Mammal diversity decreased much faster as body size increased than predicted by fractal niche theory, both at continental and at local scales, with continental distributions showing steeper slopes than the localities within them. South America showed a steeper slope (after controlling for species diversity), compared to Africa and North America, at local and continental scales. We also found that skewness and modal body size can show strikingly different correlations with predictor variables, such as species richness and median size, depending on the use of untransformed versus log-transformed data, due to changes in the distribution density generated by log-transformation. The main differences in slope, skewness, and modal size between local and continental scales appear to arise from the same biogeographical process, where small-sized species increase in diversity much faster (due to higher spatial turnover rates) than large-sized species. This process, which can operate even in the absence of competitive saturation at local scales, generates continental assemblages with steeper slopes, smaller modal sizes, and higher right skewness (toward small-sized species) compared to local communities. In addition, historical factors can also affect the size distribution slopes, which are significantly steeper, in South American mammal assemblages (probably due to stronger megafauna extinction events in South America) than those in North America and Africa. Our objective was to estimate and analyze the body size distribution parameters of terrestrial mammal assemblages at different spatial scales, to determine whether these parameters are controlled by local ecological processes or by larger-scale ones. Mammal diversity decreased much faster as body size increased than predicted by fractal niche theory, both at continental and at local scales, with continental distributions showing steeper slopes than the localities within them. We also found that skewness and modal body size can show strikingly different correlations with predictor variables, such as species richness and median size, depending on the use of untransformed versus log-transformed data, due to changes in the distribution density generated by log-transformation.

Description: Leaf area index (LAI) and canopy coverage are important parameters when modelling snow process in coniferous forests, controlling interception and transmission of radiation. Estimates of LAI and sky view factor show large variability depending on the estimation method used, and it is not clear how this is reflected in the calculated snow processes beneath the canopy. In this study the winter LAI and sky view fraction were estimated using different optical and biomass-based approximations in several boreal coniferous forest stands in Fennoscandia with different stand density, age and site latitude. The biomass-based estimate of LAI derived from forest inventory data was close to the values derived from the optical measurements at most sites, suggesting that forest inventory data can be used as input to snow hydrological modelling. Heterogeneity of tree species and site fertility, as well as edge effects between different forest compartments caused differences in the LAI estimates at some sites. A snow energy and mass balance model (SNOWPACK) was applied to detect how the differences in the estimated values of the winter LAI and sky view fraction were reflected in simulated snow processes. In the simulations, an increase in LAI and a decrease in sky view fraction changed the snow surface energy balance by decreasing shortwave radiation input and increasing longwave radiation input. Changes in LAI and sky view fraction affected directly snow accumulation through altered throughfall fraction, and indirectly snowmelt through the changed surface energy balance. Changes in LAI and sky view fraction had a greater impact on mean incoming radiation beneath the canopy than on other energy fluxes. Snowmelt was affected more than snow accumulation. The effect of canopy parameters on evaporation loss from intercepted snow was comparable to the effect of variation in governing meteorological variables such as precipitation intensity and air temperature. Copyright © 2012 John Wiley & Sons, Ltd.

Description: This paper proposes a simplified GIS-based procedure which aims to preliminary assess areas exposed to debris flows by evaluating erosion and deposition area into channels and along alluvial fans. The methodology is based on the definition of several morphometric parameters on Digital Elevation Models (DEMs); it is independent from landslide volume and its rheological characteristics. By solving a set of parametric equations and excluding, from time to time, the unlikely areas by means of an analysis process that uses on/off-raster masks, potential erosion and deposition areas can be identified. The procedure was applied at six intra-mountain basins upstream of the village of Paupisi, Southern Italy, which was involved in multiple debris flow events in October 2015. The model estimated that a range between 15–21% of the selected basin drainage channels may be identified as erosion areas. Moreover, comparison of the recent debris flow paths with model outputs shows a good performance of the procedure, which was able to predict about 46% of the total actual propagation and invasion areas and about 62% of the distribution deposit areas. The methodology can be considered a useful screening for the identification of debris flow-susceptible channels, suitable for use in preliminary hazard evaluations.