Modifications of organic matter and enzymatic activities in response to change in soil use in semi-arid mountain ecosystems (southern Spain)

Authors

  • I. Miralles,

    Corresponding author
    1. Departamento de Desertificación y Geoecología Estación Experimental de Zonas Áridas (EEZA), Consejo Superior de Investigaciones Científicas (CSIC), 04230 La Cañada de San Urbano, Almería, Spain
    2. George Lemaître Centre for Earth and Climate Research (TECLIM), Earth and Life Institute (ELI) Université Catholique de Louvain, Place Louis Pasteur, B-1348, Louvain-La-Neuve, Belgium
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  • R. Ortega,

    1. George Lemaître Centre for Earth and Climate Research (TECLIM), Earth and Life Institute (ELI) Université Catholique de Louvain, Place Louis Pasteur, B-1348, Louvain-La-Neuve, Belgium
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  • G. Almendros,

    1. Departamento de Biología Ambiental. Museo Nacional de Ciencias Naturales (MNCN), Consejo Superior de Investigaciones Científicas (CSIC), Serrano 115 B, 28006 Madrid, Spain
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  • F. Gil-Sotres,

    1. Departamento Edafología y Química Agrícola, Grupo de Evaluación de la Calidad del Suelo, Unidad Asociada CSIC, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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  • C. Trasar-Cepeda,

    1. Departamento Bioquímica del Suelo, Instituto de Investigaciones Agrobiológicas de Galicia (IIAG), Consejo Superior de Investigaciones Científicas (CSIC), Apartado 122, 15780 Santiago de Compostela, Spain
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  • M. C. Leirós,

    1. Departamento Edafología y Química Agrícola, Grupo de Evaluación de la Calidad del Suelo, Unidad Asociada CSIC, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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  • M. Soriano

    1. Departamento Edafología y Química Agrícola, Escuela Politécnica Superior, Universidad de Almería, 04120 Almería, Spain
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I. Miralles. E-mail: imirallesmellado@gmail.com

Abstract

Soil organic matter composition and biochemical properties were determined in mountain calcimorphic Mediterranean soils under different vegetation (cultivated soils, secondary bush, high mountain bush, juniper, evergreen oak and pine) to assess the impact of soil use on the size and activity of microbial communities. Our results indicated that clearing forest leads to a general decline in the performance of soil organic carbon sequestration and associated enzymatic activities. However, when soil enzymatic activities (dehydrogenase, catalase, phosphodiesterase, β-glucosidase, urease and casein-protease) were expressed as ratios to total organic carbon (specific activities), a conspicuous increase in their activities was observed in cleared soils as compared with forest soils, suggesting enhanced hydrolytic potential in the former. In addition, the negative correlation observed between qCO2 (metabolic quotient) and water retention at −1500 kPa, could be interpreted as an adaptive strategy against low soil moisture by microbial communities in cleared soils. This indicates the importance of describing soil quality in terms of long-term soil organic C sequestration and/or resistance of the organic matter to microbial transformation. These features were reflected in the visible and infrared spectra of humic acids, which suggested humification mechanisms involving mainly an alteration of plant macromolecules with poor incorporation of characteristic microbial metabolites in the forest soils whereas the opposite effect was observed in cleared soils.

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