Goncalves-Seco L.,Superior Institute of Maia |
Goncalves-Seco L.,Institute Ciencias del Patrimonio
International Journal of Geographical Information Science | Year: 2014
The analysis of the spatial structure of animal communities requires spatial data to determine the distribution of individuals and their limiting factors. New technologies like very precise GPS as well as satellite imagery and aerial photographs of very high spatial resolution are now available. Data from airborne LiDAR (Light Detection and Ranging) sensors can provide digital models of ground and vegetation surfaces with pixel sizes of less than 1 m. We present the first study in terrestrial herpetology using LiDAR data. We aim to identify the spatial patterns of a community of four species of lizards (Lacerta schreiberi, Timon lepidus, Podarcis bocagei, and P. hispanica), and to determine how the habitat is influencing the distribution of the species spatially. The study area is located in Northern Portugal. The position of each lizard was recorded during 16 surveys of 1 h with a very precise GPS (error < 1 m). LiDAR data provided digital models of surface, terrain, and normalised height. From these data, we derived slope, ruggedness, orientation, and hill-shading variables. We applied spatial statistics to determine the spatial structure of the community. We computed Maxent ecological niche models to determine the importance of environmental variables. The community and its species presented a clustered distribution. We identified 14 clusters, composed of 1-3 species. Species records showed two distribution patterns, with clusters associated with steep and flat areas. Cluster outliers had the same patterns. Juveniles and subadults were associated with areas of low quality, while sexes used space in similar ways. Maxent models identified suitable habitats across the study area for two species and in the flat areas for the other two species. LiDAR allowed us to understand the local distributions of a lizard community. Remotely sensed data and LiDAR are giving new insights into the study of species ecology. Images of higher spatial resolutions are necessary to map important factors such as refuges. © 2014 © 2014 Taylor & Francis.
Tapia T.,Institute of Astrophysics of Canarias |
Tapia T.,University of La Laguna |
Tapia T.,National Autonomous University of Mexico |
Eliche-Moral M.C.,Complutense University of Madrid |
And 15 more authors.
Astronomy and Astrophysics | Year: 2014
Context. Numerical studies have shown that the properties of the S0 galaxies with kinematics intermediate between fast and slow rotators are difficult to explain by a scenario of major mergers. Aims. We investigate whether the smoother perturbation induced by minor mergers can reproduce these systems. Methods. We analysed collisionless N-body simulations of intermediate and minor dry mergers onto S0s to determine the structural and kinematic evolution induced by the encounters. The original primary galaxies represent gas-poor fast-rotator S0b and S0c galaxies with high intrinsic ellipticities. The original bulges are intrinsically spherical and have low rotation. Different mass ratios, parent bulges, density ratios, and orbits were studied. Results. Minor mergers induce a lower decrease of the global rotational support (as provided by λe) than encounters of lower mass ratios, which results in S0s with properties intermediate between fast and slow rotators. The resulting remnants are intrinsically more triaxial, less flattened, and span the whole range of apparent ellipticities up to εe ∼ 0.8. They do not show lower apparent ellipticities in random projections than initially; on the contrary, the formation of oval distortions and the disc thickening increase the percentage of projections at 0.4 < εe < 0.7. In the experiments with S0b progenitor galaxies, minor mergers tend to spin up the bulge and to slightly decrease its intrinsic ellipticity, whereas in the cases of primary S0c galaxies they keep the rotational support of the bulge nearly constant and significantly decrease its intrinsic ellipticity. The remnant bulges remain nearly spherical (B/A ∼ C/A > 0.9), but exhibit a wide range of triaxialities (0.20 < T < 1.00). In the plane of global anisotropy of velocities (δ) vs.? intrinsic ellipticity (εe,intr), some of our models extend the linear trend found in previous major merger simulations towards higher ε e,intr values, while others clearly depart from it (depending on the progenitor S0). This is consistent with the wide dispersion exhibited by real S0s in this diagram compared with ellipticals, which follow the linear trend drawn by major merger simulations. Conclusions. The smoother changes induced by minor mergers can explain the existence of S0s with intermediate kinematic properties between fast and slow rotators that are difficult to explain with major mergers. The different trends exhibited by ellipticals and S0 galaxies in the δ - εe diagram may be pointing to the different role played by major mergers in the build-up of each morphological type. © ESO 2014.
Ferro-Vazquez C.,Institute Ciencias del Patrimonio |
Novoa-Munoz J.C.,University of Vigo |
Costa-Casais M.,Institute Ciencias del Patrimonio |
Klaminder J.,Umea University |
Martinez-Cortizas A.,University of Santiago de Compostela
Geoderma | Year: 2014
Aluminium and Fe fractions were obtained in samples from two temperate podzols by selective extraction with NaOH (Aln, Fen), Na-dithionite-citrate (Ald, Fed), acid NH4-oxalate (Alo, Feo) and Na-pyrophosphate (Alp, Fep) following the traditional fractionation procedures, and also by the use of the chlorides of K (AlK), La (AlLa) and Cu (AlCu) as non-buffered extractants for Al. Carbon content was also determined in the Na-pyrophosphate extract (Cp). Soil sampling was done at high-resolution to allow a more detailed characterization of the vertical processes than the traditional sampling by whole soil horizons. Results showed that Alp and Fep make a large proportion of the Alo and Feo meaning that organoaluminic complexes dominated in the "active" metal pool instead of inorganic compounds. The degree of metal saturation of soil organic matter (estimated by the (Alp Fep)/Cp molar ratios) increases with depth, especially in the uppermost samples of spodic horizons (Bhs1) where it increases up to 0.1. Aluminium dominates in the adsorption positions of the organic matter in the spodic horizon (Fep/Alp ratios <0.5), except in the Bhs1 horizon (ratios >1), indicating that the immobilization of Fe containing complexes occurs 10-15cm above that of Al. The highly stable Al-OM complexes accounted on average for 60% of the organoaluminic associations (>70% in the Bhs horizons). The moderately stable complexes predominate in A horizons (57-77% in ACB1 and 37-48% in ACB2) and the largest proportions of low stability complexes were found in the uppermost samples of the spodic horizons (Bhs1) of both soils (9-21%), together with the highest Fep contents and a decrease in pH values. From a stepwise multiple regression model it is suggested that pH is the main variable accounting for the stability of Al-OM compounds together with C and organically bound Fe contents. It is suggested that the illuviation of unsaturated organic acids lower the pH in upper spodic horizons, leading to the complexation of metals from formerly precipitated organometallic complexes and/or leading to their redissolution, enabling their migration to deeper soil layers. Iron complexes would be less soluble at soil pH, resulting in a differentiation of an upper Fe-rich Bhs1 horizon and a lower Bhs2 Al-rich horizon. The depth variation in C accumulation was found to be related to the proportion of highly stable Al-OM fraction. © 2013 Elsevier B.V.
Deciphering the evolution of agrarian technologies during the last ~1600 years using the isotopic fingerprint (δ13C, δ15N) of a polycyclic terraced soil [Descifrando la evolución de las tecnologías agrarias durante los últimos ~1.600 años utilizando la huella isotópica (δ13C, δ15N) en un suelo aterrazado policíclico]
Vazquez C.F.,Institute Ciencias del Patrimonio |
Prieto S.G.,CSIC - National Institute of Agrobiological Sciences |
Cortizas A.M.,University of Santiago de Compostela |
Boado F.C.,Institute Ciencias del Patrimonio
Estudos do Quaternario | Year: 2015
We analyzed the isotopic (13C and 15N) composition of a polycyclic terraced soil located in Santiago de Compostela (NW Spain) and compared it with previous results on total aluminum, iron and silicon and their fractionation by selective dissolution techniques. The aim was to recognize the imprints of land management changes, with particular attention to fertilization techniques applied during the use history of the terrace (~1600 y). The buried paleosol, found below the terraced layers, is considered to preserve the soil properties prior to the terrace construction. The isotopic composition (13C, 15N) provided evidence of extensive land use previous to the construction of the terrace, with the utilization of fire as liming and clearance tool. In the Late Antiquity and Early Medieval Ages the soil use was more intense and amendments with vegetal remains from nitrogen fixing shrubs were likely applied. Since the Early Middle Ages, animal wastes were used as a way to maintain or increase soil fertility because of an intensification of the agrarian use. © 2015, Associacao Portuguesa para o Desenvolvimento Regional (APDR). All rights reserved.
Ferro-Vazquez C.,Institute Ciencias del Patrimonio |
Martinez-Cortizas A.,University of Santiago de Compostela |
Novoa-Munoz J.C.,University of Vigo |
Ballesteros-Arias P.,Collaborator of the Institute Ciencias del Patrimonio CSIC |
Criado-Boado F.,Institute Ciencias del Patrimonio
Quaternary International | Year: 2014
Colluvial soils can store signals of the environmental conditions occurred during their formation, including the anthropogenic activities they supported. Their study may provide important information for reconstructing and interpreting the evolution of cultural landscapes. We studied the chemical properties of a terraced soil system located in the town of Santiago de Compostela (NW Spain). Aluminum, Fe and Si fractionation was studied by selective dissolution techniques with high vertical resolution, combined with elemental composition and other soil properties such as phosphate retention (Pret) and NaF pH, aiming to identify modifications produced by land use changes and agricultural management practices since Antiquity. The buried epipedon of the paleosol, which is considered to exemplify the pre-terracing soil, showed strong andic character. We argue that its attenuation in the anthropogenic soil layers is, firstly, a consequence of the decreasing amounts of reactive components (organic matter, organo-Al complexes and low ordered aluminosilicates) due to a dilution by mixing superficial and sub-superficial horizons. Secondly, the introduction of agricultural techniques led to modifications in the chemical stability of organo-metal complexes influencing the accumulation of organic matter. Other signals, such as variations in soil acidity, and P and Ca contents, point to management practices as fertilization or liming. The increasing amounts of Fe inorganic compounds in the more recent layers indicate a strong weathering and degradation, probably as a consequence of the intensification of the agricultural use. Our results indicated continued and progressively more intensive agricultural use during the last 15 centuries, linked to the development of the town. © 2014 Elsevier Ltd and INQUA.