Santiago de Compostela, A Coruña, Spain

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    ABSTRACT: In this study we present a methodology to estimate and map the content of Soil Organic Carbon (SOC) in topsoils from spectroscopic measurements (FTIR-ATR). We used the Walkley-Black method to determine the SOC content in 221 topsoil samples in Galicia. FTIR-ATR spectroscopic data was measured upon the same set of samples. A Random Forest (RF) model, linking SOC and FTIR-ATR data, revealed that the spectral band placed at 1697 cm-1, explains most of the variability of SOC. We crossed the spectroscopic data for this wavenumber with a number of raster environmental data (climate, land use and geology) using Partial Least Squares (PLS) to create maps depicting the spatial distribution of such band. A linear regression model (MLR), relating SOC as the dependent variable and the selected FTIR-ATR bands as independent proxy, shows a good predictive performance (r-squared =0.88; RSME = 2.14; ME = 0.05). We used this MLR, upon the PLS model, to generalize the distribution of SOC in our study area. This approach shows that FTIR-ATR data can be used to directly map SOC while minimizing analytical costs and time.
    No preview · Article · Dec 2015
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    ABSTRACT: Soil bulk density is an important soil parameter directly related to a number of soil properties and processes and required to estimate element stocks in soils on an area basis. The measure of ρb is expensive and time-consuming and thus is often excluded from ordinary analyses. It is thus necessary the development of proper pedotransfer functions (PTF) to estimate ρb from parameters ordinarily included in soil analyses. In this study we used a geochemical database of 115 epipedons from Galicia (NW Spain) to test 3 different statistical methods – multiple linear regression, random forest and neural networks – in order to develop a PTF linking bulk density to organic matter content and soil textural fractions. Random forest was the model that presented the highest predictive performance (R-squared=0.90; RMSE=0.14; ME=0.03). This PTF was used to generalize a map of ρb covering the study area. Soil bulk density in Galicia is mainly related to the soil carbon content, peat soils being the features with lower ρb in this study area.
    Full-text · Article · Dec 2015
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    ABSTRACT: Los estados financieros numéricos, para su adecuada interpretación, necesitan ser enmarcados en un contexto de referencia, datos facilitados por la empresa en su información narrativa. El objetivo del presente trabajo es el estudio de la neutralidad de la información contenida en el informe de gestión, cualidad fundamental para que la información divulgada por las empresas sea fiable y, por lo tanto, de calidad. Para ello analizamos el empleo de diversas estrategias de manipulación de la información narrativa durante el período 2007-2009 en una muestra de empresas españolas cotizadas. Los resultados alcanzados respaldan la hipótesis de que la información narrativa está orientada hacia las relaciones públicas, siendo utilizada para tratar de construir y proyectar una determinada imagen. Así, cuando las empresas sufren un deterioro en su desempeño financiero, son poco objetivas en la descripción de dicho desempeño: elaboran una información de difícil lectura, no emplean un tono pesimista y no divulgan más noticias malas que buenas. Además, en estas empresas se tiende a atribuir la responsabilidad de las malas noticias a factores externos a las mismas.
    Full-text · Article · Dec 2015 · Revista de Contabilidad

Information

  • Address
    Colexio de San Xerome, Praza do Obradoiro, s/n., 15782, Santiago de Compostela, A Coruña, Spain
  • Head of Institution
    Juan Viaño Rey
  • Website
    www.usc.es
  • Phone
    0034881 811 001
  • Fax
    0034881 811 201
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