Pedogenesis and carbon sequestration in transformed agricultural soils of Sicily

The increasing atmospheric CO2 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 CO2 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 CO2 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 CO2 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 CO2 consumption represents only an estimate. When summing up organic C sequestration and CO2 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 CO2 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

The use and limits of ITS data in the analysis of intraspecific variation in Passiflora L. (Passifloraceae)

The discovery and characterization of informative intraspecific genetic markers is fundamental for evolutionary and conservation genetics studies. Here, we used nuclear ribosomal ITS sequences to access intraspecific genetic diversity in 23 species of the genus Passiflora L. Some degree of variation was detected in 21 of these. The Passiflora and Decaloba (DC.) Rchb. subgenera showed significant differences in the sizes of the two ITS regions and in GC content, which can be related to reproductive characteristics of species in these subgenera. Furthermore, clear geographical patterns in the spatial distribution of sequence types were identified in six species. The results indicate that ITS may be a useful tool for the evaluation of intraspecific genetic variation in Passiflora

Classification of Camellia (Theaceae) Species Using Leaf Architecture Variations and Pattern Recognition Techniques

Leaf characters have been successfully utilized to classify Camellia (Theaceae) species; however, leaf characters combined with supervised pattern recognition techniques have not been previously explored. We present results of using leaf morphological and venation characters of 93 species from five sections of genus Camellia to assess the effectiveness of several supervised pattern recognition techniques for classifications and compare their accuracy. Clustering approach, Learning Vector Quantization neural network (LVQ-ANN), Dynamic Architecture for Artificial Neural Networks (DAN2), and C-support vector machines (SVM) are used to discriminate 93 species from five sections of genus Camellia (11 in sect. Furfuracea, 16 in sect. Paracamellia, 12 in sect. Tuberculata, 34 in sect. Camellia, and 20 in sect. Theopsis). DAN2 and SVM show excellent classification results for genus Camellia with DAN2's accuracy of 97.92% and 91.11% for training and testing data sets respectively. The RBF-SVM results of 97.92% and 97.78% for training and testing offer the best classification accuracy. A hierarchical dendrogram based on leaf architecture data has confirmed the morphological classification of the five sections as previously proposed. The overall results suggest that leaf architecture-based data analysis using supervised pattern recognition techniques, especially DAN2 and SVM discrimination methods, is excellent for identification of Camellia species

Alpha shapes: Determining 3D shape complexity across morphologically diverse structures

Background. Following recent advances in bioimaging, high-resolution 3D models of biological structures are now generated rapidly and at low-cost. To utilise this data to address evolutionary and ecological questions, an array of tools has been developed to conduct 3D shape analysis and quantify topographic complexity. Here we focus particularly on shape techniques applied to irregular-shaped objects lacking clear homologous landmarks, and propose the new ‘alpha-shapes’ method for quantifying 3D shape complexity. Methods. We apply alpha-shapes to quantify shape complexity in the mammalian baculum as an example of a morphologically disparate structure. Micro- computed-tomography (μCT) scans of bacula were conducted. Bacula were binarised and converted into point clouds. Following application of a scaling factor to account for absolute differences in size, a suite of alpha-shapes was fitted to each specimen. An alpha shape is a formed from a subcomplex of the Delaunay triangulation of a given set of points, and ranges in refinement from a very coarse mesh (approximating convex hulls) to a very fine fit. ‘Optimal’ alpha was defined as the degree of refinement necessary in order for alpha-shape volume to equal CT voxel volume, and was taken as a metric of overall shape ‘complexity’. Results Our results show that alpha-shapes can be used to quantify interspecific variation in shape ‘complexity’ within biological structures of disparate geometry. The ‘stepped’ nature of alpha curves is informative with regards to the contribution of specific morphological features to overall shape ‘complexity’. Alpha-shapes agrees with other measures of topographic complexity (dissection index, Dirichlet normal energy) in identifying ursid bacula as having low shape complexity. However, alpha-shapes estimates mustelid bacula as possessing the highest topographic complexity, contrasting with other shape metrics. 3D fractal dimension is found to be an inappropriate metric of complexity when applied to bacula. Conclusions. The alpha-shapes methodology can be used to calculate ‘optimal’ alpha refinement as a proxy for shape ‘complexity’ without identifying landmarks. The implementation of alpha-shapes is straightforward, and is automated to process large datasets quickly. Beyond genital shape, we consider the alpha-shapes technique to hold considerable promise for new applications across evolutionary, ecological and palaeoecological disciplines

Mineral and geochemistry of clay-sized fractions from sediments of the Oligocene maar near Baruth (Saxony, Germany)

Twenty seven clay-sized (<2 μm) separates from drill core samples of the Upper Oligocene maar near Baruth, Saxony, were mineralogically and chemically characterized using X-ray diffraction analysis coupled with the Rietveld method, X-ray fluorescence analysis, scanning and transmission electron microscopy, and stable isotope analysis. The predominant minerals in the clay fractions are kaolin minerals (kaolinite and halloysite) and opal-A. Abundant Fe- and smectite-rich illite-smectite mixed-layer minerals occur exclusively in the lower turbidites and debris flows. Illite and beidellites are minor components. Accessory phases are anatase, siderite, sanidine, quartz, albite-rich plagioclase, and pyrite. Four main detrital components were detected in the Upper Oligocene maar sediments: 1) biogenic opal-A as diatom fragments, 2) disordered kaolinite (and halloysite) + illite + beidellite + Zr-rich anatase from soils on granodioritic material, 3) Fe- and smectite-rich I-S from weathered basaltic volcanic material and 4) sporadic eolian input of sanidine-bearing, probably phonolithic, ashes. The Mid-Miocene kaolinite-rich clays that cover the maar sediments were derived from eroded saprolites on the Lausitz granodiorite. The δD and δ18O values of the kaolinite-rich clay fractions from various lithologies indicate kaolinization at temperatures of ~15 ± 5 °C from meteoric waters that were isotopically heavier than present-day meteoric waters. There is no evidence for hydrothermal clay formation in the maar

Clay minerals, oxyhydroxide formation, element leaching and humus development in volcanic soils

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

Recognition and differentiation of species in the Passiflora sidifolia complex

The variation in leaf morphology observed in Passifloraceae is one of the most extreme cases in the Angiosperms, allowing some species within this family to be distinguished by their leaves. Nevertheless, other species in this family are difficult to recognize based solely on leaf morphology, or by floral and molecular characteristics. Aiming to verify the similarities and differences between the Passiflora species Passiflora actinia Hook., Passiflora elegans Mast., Passiflora sidifolia M.Roem., and Passiflora watsoniana Mast., detailed analyses were conducted regarding the morphological traits of the leaf blade, specifically shape and venation, and the flower. The data were composed of continuous and qualitative values, using the Gower coefficient. A principal coordinates analysis (PCoA) and cluster analysis were performed. Features that have not previously been used for the Passifloraceae, such as leaf venation, were important for the distinction of P. watsoniana from the other species. The analyses including only the species P. actinia, P. sidifolia, and P. elegans showed a clear differentiation between them. Despite the wide variability observed in P. elegans, the analysis revealed that the different populations from different regions had more similarities with each other than with any other species.9312809824FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP04/14436-6La variation de la morphologie foliaire observée chez les Passifloracées qui permet a` certaines espèces a` l’intérieur de cette famille de se distinguer par leurs feuilles constitue l’un des exemples les plus extrêmes chez les angiospermes. Néanmoins, d’autres espèces de cette famille sont difficiles a` reconnaître sur la seule base de la morphologie de leur feuilles ou des caractéristiques florales et moléculaires. Afin de vérifier les similarités et les différences entre les espèces de Passiflora Passiflora actinia Hook., Passiflora elegans Mast., Passiflora sidifolia M.Roem. et Passiflora watsoniana Mast., des analyses détaillées ont été réalisées relativement aux traits morphologiques du limbe foliaire, spécifiquement la forme et la nervation, ainsi qu’a` la fleur. Les données étaient composées de valeurs continues et qualitatives, a` l’aide du coefficient de Gower. Une analyse en coordonnées principales (ACP) et une analyse de grappes ont été réalisées. Les caractéristiques qui n’avaient pas encore été utilisées chez les Passifloracées, comme la nervation des feuilles, étaient importantes pour distinguer P. watsoniana des autres espèces. Les analyses incluant les seules espèces P. actinia, P. sidifolia et P. elegans montraient une différenciation claire entre elles. Malgré la grande variabilité observée chez P. elegans, l’analyse a révélé que les différentes populations de différentes régions partageaient davantage de similarités entre elles qu’avec aucune autre espèc